Inverter, Storage and PV System Technology
“Inverter, Storage and PV System Technology” takes a close look at the electrical components of the PV system and its interactions, presents the latest technical developments, and gives an overview of market conditions.
Inverter, Storage and PV System Technology
Corporate portraits of international companies round off this comprehensive industry guide on PV system technology. www.pv-system-tech.com
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Cover images Front Main image Vented stationary lead-acid battery with a liquid electrolyte. The tubular plates technology is designed to result in a large number of cycles during the batteries’ lifetime. (Photo: Tom Baerwald/HOPPECKE Batterien GmbH & Co. KG) Small images, f.l.t.r. Taking measurements using a thermal imaging camera (Photo: Tom Baerwald/Lebherz) Central inverter in a ground-mounted installation (Photo: Tom Baerwald) String inverter in an electromagnetic compatibility (EMC) test chamber (Photo: SMA Solar Technology AG) Back Climate chamber test to ensure that inverters withstand extreme temperature variations (Photo: SMA Solar Technology AG)
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Inverter, Storage and PV System Technology Industry Guide 2013
Contents
Foreword by K. H. Remmers, CEO Solarpraxis AG .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
The Industry
Photovoltaic Plants and the Importance of Electrical Components . . . . . . . . 8
Contents
The PV Generator .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Inverters and PV Plant Yield .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Inverters and Grid Integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Storage Systems and Energy Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Plant Monitoring and Identifying Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
Stand-Alone Power Systems and Grid-Parallel Operation .. . . . . . . . . . . . . . . . . . . . . . 40
Market Situation and Forecasts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
The Companies
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Business Areas .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
ABB .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Protection against Lightning and Overvoltage .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Cables and Connectors .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
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Advanced Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 AEG Power Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Bonfiglioli Riduttori S.p.A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Bosch Power Tec GmbH .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 Danfoss Solar Inverters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Diehl Controls – PLATINUM® GmbH .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Fronius Deutschland GmbH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
GoodWe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
W. L. Gore & Associates GmbH .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Ingeteam Power Technology S.A. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 KOSTAL Industrie Elektrik GmbH
.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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KOSTAL Solar Electric GmbH .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
LTi REEnergy .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Mastervolt International BV .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
meteocontrol .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 Multi-Contact AG .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Nidec ASI S.p.A. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 OBO BETTERMANN GmbH & Co. KG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Phoenix Contact GmbH & Co. KG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 Power-One . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
REFUsol GmbH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
Steca Elektronik GmbH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Publishers
Solarpraxis AG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Sunbeam GmbH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Important Notice, Picture Credits, Sources .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Saft .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 Schneider Electric .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
skytron® energy GmbH .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 SMA Solar Technology AG .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Solare Datensysteme GmbH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
SolarMax .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
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Legal Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
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Foreword
Foreword Dear Readers, With the global amount of newly installed photovoltaic capacity expected to increase from today’s annual level of around 30 gigawatts (GW) to more than 300 GW per year by 2025, the development of solar technology is unstoppable.
Karl-Heinz Remmers, CEO of Solarpraxis AG
However, the success of the energy revolution is no guarantee. Without a doubt, 2012 has been the most difficult year for the solar industry in a long time. Despite a marked drop in solar energy prices and many new markets emerging around the world, the market’s strong dynamism has led to considerable financial difficulties and even insolvencies. This is because the high level of dynamism was, and indeed still is, also characterized by insecure conditions: Many governments are stalling the developments by making sudden, drastic cuts to subsidy programs, and even the substantial drop in solar power generation costs was unable to compensate for the insecurity felt amongst companies and customers, causing severe job losses in the industry. Despite these difficult conditions, the PV industry was still able to demonstrate its innovative power. Up until two years ago, storage systems were only of minor interest – even in this brochure. Today, however, they are on their way towards becoming an important up-and-coming market. This is because the two sources of energy which are experiencing the greatest levels of growth worldwide are both fluctuating in nature: Unlike fossil-fuel or nuclear power stations, the amounts of electricity that solar and wind power plants feed into the grid varies, which is why these energy sources depend on powerful storage systems. Additionally, our electricity grids have been inherited from the age of industrialization. They were built in order to transport electricity from centralized coal-fired power stations – and later from large nuclear plants – to conurbations and industrial centers. The energy revolution changes all that: The grid of
the future not only has to distribute electricity, but must also collect power from decentralized generators. A great number of companies are currently working on storage solutions which are able to interact with the grid intelligently. This innovative strength has not yet received any political support – not even in Germany, the country which can still call itself a technological leader in solar energy. When the announced, and admittedly rather meager, 50 million euros of funding for storage systems will actually become available remains unclear. Negotiations with the German Federal Ministry for the Environment concerning the funding conditions had almost been concluded, and the banks had already been informed of the necessary procedures, when the program was suddenly shelved. While the manufacturing industry is working on pioneering solutions, the German government is paying no more than lip service. Storage systems and the integration of decentralized storage into the power grid will play a decisive role in the reorganization of our power supply in the future. The course has to be set now because despite all the setbacks it is facing, renewable energy will continue to flourish. Intelligent storage systems will not only steadily increase in importance, but will soon become essential. The industry has understood this state of affairs. Now it is high time for governments to grasp it as well. Kind regards,
Karl-Heinz Remmers, CEO Solarpraxis AG
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The Industry
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Photovoltaic Plants and the Importance of Electrical Components
Photovoltaic Plants and the Importance of Electrical Components Grid-connected PV plants have become so numerous even in some parts of Germany that on sunny days their output exceeds consumption in the region. This is why, especially in industrialized countries, the further expansion of photovoltaics must go hand in hand with the expansion of centralized and decentralized storage systems so that an increasing part of this surplus can be consumed close to the source. Furthermore, with the growing importance of on-site consumption and more and more grid-connected PV systems being equipped with battery storage, the differences between on-grid and off-grid photovoltaics are slowly disappearing, and inverters are turning into energy management systems. Battery power plant in the technology center of a renewable energy systems developer P hoto : Younicos Technologie z entrum
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Photovoltaic Plants and the Importance of Electrical Components
Power generation and grid services A photovoltaic plant (PV plant) that feeds all the power it generates into the grid essentially consists of the following components: • PV generator (solar modules) • support structure (mounting frame) • generator junction box (GJB) • inverter • monitoring system • feed-in meter • grid connection • direct current (DC) and alternating current (AC) cabling Careful planning is critical to achieving the optimum balance between a plant’s components. These are continually undergoing further development to
increase yield and efficiency. When integrating these components into a single system, the different module types available (modules with crystalline silicon solar cells or modules based on the various thin film technologies) must be given just as much consideration as the everincreasing functions of the inverter.
From purely feeding the maximum amount of energy into the grid through providing grid services, the inverter must now also develop itself into an energy manager that assesses the different options available for utilizing the solar power and then identifies the most profitable solution in each situation.
Photovoltaic systems need to do more than simply feed energy into the grid if they are to make an adequate contribution to the power supply. Installations must also play a role in stabilizing the grids, for example by supplying reactive power, supporting grid frequency or keeping an installation on the grid when there are grid failures. This is why, as the systems’ intelligence centers, inverters are also increasingly required to perform grid services.
Private power supply is becoming increasingly distributed. Ever more PV system operators are themselves consuming the power generated on their roofs. PV systems technology is set to develop further as a result of this. This will particularly affect inverters, as they guide the solar power either into the household network, a power storage system or the public grid, depending on supply and demand.
P hoto : Tom Baerwald
P hoto : S M A S olar Technology AG
Ideas are transformed into marketable products in the industry's development departments.
The PV plant in Senftenberg (Brandenburg, Germany) was the largest solar park in the world when it was commissioned in 2011. It comprises three units with a total output of more than 160 MW.
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Photovoltaic Plants and the Importance of Electrical Components
PV system components (possible designs) 1.
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2. 3.
5.
7.
3.
4. 9. 1.
2.
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1. PV generator (solar modules) 2. Solar module junction box 3. Solar cable connector 4. Power optimizer 5. Generator junction box (GJB) 6. Monitoring solutions 7. Inverter 8. Fuse box 9. Consumer 10. Battery storage 11. Import/export meter 12. Grid supply
Centralized and decentralized storage systems Accumulators (batteries) offer a great option for storing surplus solar power and then feeding it into the domestic grid as required. This provides a new application for traditional lead-acid batteries, although new (e.g. lithium-based) storage systems are also being developed. New developments are still very expensive, meaning that initially their market is expected to grow slowly. If the necessary expansion of storage capacity is to keep up with the increasing amount of power being generated, the specific costs per stored kilowatt hour and per kilowatt hour withdrawn from storage (euros/kWh) must be reduced while the cycle life of batteries must be increased.
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10. 00123467
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DC AC
The market for storage systems is still too young, however, to foresee which technologies will secure a large foothold. A likely future scenario will involve a mixture of distributed, short-term storage systems and large, seasonal storage systems that are capable of storing surplus energy for several weeks or even months. Off the grid Photovoltaics is not just growing in importance in regions supplied by the public grid. In areas without grid connection – or where diesel generators are still the main power source – and where sufficient insolation is available, PV plants are able to generate electricity relatively cheaply. This is because off-grid supply is usually cheaper than connecting to a far-away grid. As a result, ever growing numbers of
12.
standalone PV systems are springing up in sparsely populated or technologically less developed regions in Asia and Africa. Hybridizing diesel power supply systems by combining them with a PV plant in order to reduce fuel costs is already cost-effective today. PV systems are also increasingly popular in areas with an unreliable public grid due to frequent grid failures and power fluctuations. Here they operate in parallel to the grid and support it when necessary. Off-grid and on-grid systems are growing together.
The PV Generator
The PV Generator Electrically connected solar modules make up a PV generator, which generates electrical power dependent on insolation and temperature. The output of a solar generator is therefore not only determined by the efficiency of its modules, but also by how well those modules exploit the strength and spectrum of the insolation, and how they react to the module temperature.
Perovo Solar Park in Crimea (Ukraine) with an output of 100 MW. The plant uses a turnkey monitoring system that is integrated into the inverter stations. P hoto : Activ S olar G mb H
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The PV Generator
Efficiency and surface area The photovoltaic effect in solar cells can be used to generate power in several ways. Solar cells are made from a variety of different materials, with crystalline silicon being the most common. Thinfilm cells made from cadmium telluride (CdTe), copper indium/gallium disulfide/ diselenide (CIGS), amorphous silicon (aSi) and amorphous/microcrystalline silicon (a-Si/μc-Si) are also extensively used. Several solar cells are connected together to make up a module, several modules in series are connected together to form strings and several strings in parallel create the solar generator. The electrical properties of crystalline modules are markedly different from those of thinfilm modules and must be taken into account in order to achieve the highest possible yield in a given location.
Cell material
P hoto : Tom Baerwald
Quality testing by independent experts guarantees that the completed PV plant is consistent with its planning documents and yield reports.
Since modules made from crystalline silicon are generally more efficient than thin-film modules, they are used wherever space is at a premium, such as on the roofs of single-family homes. Module efficiency therefore solely affects the space requirements for the PV plant: In the case of crystalline solar modules, an area of around five to nine square meters (m2) is needed to achieve an output of one kilowatt peak (kWp), whereas for thin-film modules the area required for the same output is between 8 and 20 m2 – depending on the technology used. On the one hand, this means that the cost of support structures and installation is higher for thin-film solar modules as surface area efficiency is usually lower, and that the modules themselves must therefore be somewhat cheaper in a turnkey system of the same price. On the
Module efficiency
Surface area need for 1 kWp
Monocrystalline silicon
13–19%
5–8 m2
Polycrystalline silicon
11–15%
7–9 m2
Micromorphous tandem cell (a-Si/μc-Si)
8–10%
10–12 m2
10–12%
8–10 m2
Thin-film cadmium telluride (CdTe)
9–11%
9–11 m2
Amorphous silicon (a-Si)
5–8%
13–20 m2
Thin film copper-indium/gallium-sulfur/ diselenide (CI/GS/Se)
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other hand, the area required only has an indirect effect on the specific yield of a PV plant, which is indicated in kWh/kWp. To calculate the specific yield, the electricity output (in kWh) is related to the installed system capacity (in kWp) so that module efficiency becomes immaterial. All in all, with trouble-free operation, the specific yield and costs of photovoltaic installations – and thus their profitability – are roughly the same whether crystalline silicon modules or thin-film modules are used. The cost of land plays a secondary role when installing ground-mounted systems, as economies of scale come into play in such installations. In recent years, ground-mounted systems have therefore often been built using thin-film solar modules, though the astonishingly sharp drop in prices for crystalline silicon modules has now caused the thin-film market share to diminish again. This is not only the case with ground-mounted installations but in all market segments. Crystalline silicon solar cells are particularly responsive to long-wave solar radiation. In contrast, thin-film modules make better use of the short and medium-wave range of the solar spectrum. In cloudy con-
Cells made from different materials have different efficiencies. PV array surface area depends on the type of cell used.
The PV Generator
MPP output dependent on temperature 15
Relative change (%)
10 STC (Standard Test Conditions)
5 0 -5 -10
PMPP aSi
PMPP Power maximum power point
PMPP CdTe
-15 -20
PMPP cSi
-5
5
15
25
35
45
55
65
Temperature (°C)
Temperature coefficient of the output power in MPP (PMPP): As the temperature increases, the PV module output drops steadily. Crystalline modules (cSi) are far more severely affected by this than thin-film modules (aSi and CdTe).
ditions, the spectrum that hits the ground has a higher proportion of shortwave light, which is best exploited by amorphous thin-film modules. CdTe, CI/GS/Se and microcrystalline thin-film modules, on the other hand, are best suited to absorbing medium wavelengths. In general, thin-film modules are ideal for sites which experience a high proportion of diffuse insolation due to frequent cloudy weather, or temporary or partial shading. Furthermore, they offer advantages when the orientation of the solar modules (for example on an east- or west-facing roof) is not ideal. Despite their lower efficiency, which is measured in laboratory simulations under artificial sunlight with an intensity of 1,000 watts per square meter (W/m2), at module temperatures of 25°C and with spectral irradiance at an air mass of 1.5 (standard test conditions, STC), the electricity yield of thin-film modules can be comparatively high under certain conditions. On the one hand, this is linked to the temperature coefficient gradient, which is markedly different to that of a crystalline module. On the other, the specific yield in kWh/kWp is a variable which is not related to surface area, meaning that the lower efficiency of individual modules becomes irrelevant for comparison.
The temperature coefficient
are characterized by a lower temperature coefficient of output, typically –0.3%/K. This means that at a module temperature of T=55 °C, the solar module would only show a drop in output of 9%.
The temperature coefficient of voltage – and consequently also the module output determined by voltage times current – is negative. This means that the module output and voltage (when compared to the data sheet and nameplate capacity) decrease at high temperatures (higher than the reference temperature T=25°C under STC). Conversely, they increase at low temperatures. The temperature coefficient of current is both very small and positive, so currents will only alter to a very small degree as a result of temperature fluctuations, therefore only exerting very little influence on module output.
Insolation can heat PV modules to as much as 70 °C. For this reason, they are installed so as to ensure that air can circulate to provide sufficient rear ventilation. Where rear ventilation is not possible, for instance if the modules are integrated into the roof or façade of a thermally insulated building, thin-film modules are better suited as their actual output is less dramatically impaired by high temperatures.
Here is an example with some typical values: Under STC, a given solar module with crystalline silicon solar cells has a nominal output of 200 watts peak (Wp) and the temperature coefficient of output is –0.5%/kelvin (K). This means that the output of this module would decrease by 5% for every temperature increase of 10 K. If this module were to reach a temperature of T=55 °C, the output would drop by 15%, i.e. the 200 Wp module would “only” supply 170 Wp. Inversely, at a module temperature of T=5 °C, its output would increase to 220 Wp. Thin-film modules
(f. l. t. r.:) Roof-mounted installation in Germany Carport in Tongeren (Belgium) with the PV system inverters on lefthand side Ground-mounted installation in France
P hoto : S iemens AG
P hoto : R efusol G mb H
P hoto : Colexon E nergy AG
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The PV Generator
Bypass diode
cell 1
cell 2
Bypass diode
cell 20
cell 21
cell 22
The reduced output and possibility of damage to cells and modules caused by shading can be mitigated by the use of bypass diodes. The diode short circuits the affected area and allows the current to bypass it.
Bypass diodes against overheating Since a single solar cell is only able to generate around 0.5 volts (V), a number of cells within a module are connected in series to form a string. This has the disadvantage of making the module extremely sensitive to partial shading because when a shadow is cast on a cell, e.g. from a chimney, dormer or an antenna, the cell can no longer generate power, turning it from power generator to power consumer. As the weakest link in the chain, the cell restricts the power output of the entire string. Shaded cells do not generate electricity, while the other, fully illuminated cells in the string remain completely active and drive their power through the shaded cell, which converts that power into heat. In extreme cases, this leads to a “hot spot” being created in the cell, which can melt a hole in the cell material. A bypass diode, which bypasses the module string containing the shaded cell, is therefore used to steer the electricity past the passive cell. A bypass diode usually bypasses 20 to 24 cells. Today, modules consisting of 60 to 72 cells are often equipped with three bypass diodes which are located in the module junction boxes. As each diode bypasses a part of the module, in the case of very slight shading, only some of the output of all the series-connected cells making up the module will be lost. It would therefore be ideal if each solar cell could be equipped with a bypass diode. Unfortunately, the junction box does not provide enough space for this. To get
14
around the problem, several manufacturers have started to laminate “string bypass diodes” into their modules. This allows a greater number of diodes to be used than will fit in the junction box, and shading tolerance is noticeably increased as a result.
centrator modules only utilize the part of the global insolation that reaches them directly and must follow the sun on a dual-axis tracking system. Their output is therefore at its highest along the earth’s sun belt.
Overall, shading has the same effect as sharply reduced insolation: a decreased flow of current. This applies in principle to both crystalline and thin-film modules. However, the latter benefit from the strip-like arrangement of their solar cells, as it is relatively uncommon for long, narrow, thin-film solar cells to become completely shaded. The reduction in output of a thin-film module is therefore usually proportionate to the shaded area.
Module junction box
Where losses are expected due to high operating temperatures or shading, thinfilm modules are often given preference over crystalline silicon models. Concentrated photovoltaics As efficiency increases with greater radiation intensity, the efficiency of solar cells can also be raised by concentrating the sunlight that falls on them with mirrors or lenses. In theory, multiplying the concentration of sunlight by 100 produces a 20% increase in output. Concentrator cells fitted with Fresnel lenses can be combined relatively easily into modules. Modules that are ready for mass production achieve an efficiency of around 25% with a concentration factor of 500. As diffused sunlight reaches the lens system from all directions, it cannot be focused on the cells. Consequently, con-
Module junction boxes connect solar cells to the outside world by joining the connection cables of the cell strings and interconnecting them with the bypass diodes and the module connection cables. To prevent moisture from entering the module junction box, it is waterproofed and often sealed with silicon. Little by little, electrical functions are being incorporated into the module junction box to provide additional safety or increase the yield. DC/DC converters ensure that the voltage output is optimal for the inverter, irrespective of shading and temperature. Even performance boosters (e.g. power optimizers – see “Inverters and PV Plant Yield”) can be incorporated into the junction box. Each module will then have its own MPP controller. PV generator safety can be increased by automatic fire prevention systems, also located in the module junction box. Reflection losses In order for yield to be increased even further, reflection losses must also be taken into account. Modules with anti-reflection glass are already in use, but are relatively expensive. Reflection losses can, however, be virtually eliminated if the PV generators are equipped to track the sun’s movement on a dual axis, though
The PV Generator P hoto : D eutscher Zukunftspreis
Multi-junction solar cells are used in concentrated photovoltaics. They capture different wavelength ranges of sunlight and are combined with lenses that concentrate sunlight.
this involves relatively high additional expense for the mechanical system. Such outlay is really only worthwhile if adequate additional yield can be achieved, i.e. if the PV system is installed at a site with a high proportion of direct insolation, preferably along the earth’s sunbelt. This applies similarly to concentrating sunlight with mirrors or optical lenses. Yield can also be increased by active cooling. Here, cooling modules on their rear side produces warm water or warm air in addition to electricity. All in all, the advantages of this method are, however, too few for it to have become well-established. Aging processes Since they contain no moving parts, solar modules normally age very slowly. As long as their materials (glass, solar cells, plastics, aluminum) have been carefully selected, they are also sufficiently weather resistant. If a system is installed in such a way that corrosion cannot take hold, it can achieve a service life of 20 years or more. The assembly frame should be designed to ensure that there are no corners or niches where dirt, leaves and other deposits could collect, and standing water should also be avoided. Different metals may only be used together if it can be guaranteed that no electrochemical reaction will take place. This particularly applies to the screws and clamps in the support frame that holds the PV generator.
of most thin-film modules to conduct current, was often damaged by corrosion. TCO corrosion is irreversible and leads to severe output losses. Such damage predominantly occurs in the event of high voltages caused by earth leakage currents. Grounding the generator’s negative pole can prevent TCO corrosion, though it also precludes the use of several inverter types. Generator junction box The modules are connected in series to form a string. The cumulative voltage of the individual modules gives the string voltage, which must be calibrated to the system voltage of the inverters. Strings of equal length are then connected in parallel to make up the PV generator, where the output power of the strings is cumulative. Multiple string cables from the PV generator are consolidated using Y-adapters or joined in a GJB.
The GJB is located close to the modules and connects several strings in parallel, meaning that only one positive and one negative cable – albeit with large cable cross sections – must be laid from each junction box to the downstream inverter. It can also perform additional safetyrelated functions, such as those of string fuses or overvoltage conductors. If thinfilm modules are used which are not reverse current proof, blocking diodes must also be employed. In addition, there are certain components which may be positioned in several different locations within the system. For example, the main DC switch could be a part of the GJB or could be integrated into the inverter.
Generator junction box 1.
2.
3.
4. 1. Blocking diodes 2. DC switch 3. Surge suppressor 4. String fuses
In the early days of PV technology, the transparent conductive oxide (TCO) coating, applied to the illuminated upper face
15
Inverters and PV Plant Yield
Inverters and PV Plant Yield Major discrepancies exist between power generation with PV modules and the requirements of the public grid. The job of the inverter is to connect the systems with each other and to feed the solar power into the grid with the highest possible efficiency. A PV installation’s yield is, therefore, just as heavily dependent on the reliability and efficiency of the inverter as on the orientation, interconnection and quality of the PV modules.
Construction of an inverter station in a large solar park P hoto : Tom Baerwald / Parabel AG
16
Inverters and PV Plant Yield
I-V curve of a crystalline silicon solar cell 4
MPP 2
0.4
1
0 The open circuit voltage (VOC) is around 0.5 V. At the maximum power point (MPP) of the curve, the voltage is about 80% of the open circuit voltage (VOC) and the current is about 95% of the short circuit current (ISC).
Automatic search for the maximum power point The inverter represents the link between the solar generator and the public power grid, and must therefore perform several tasks simultaneously. The most important of these are MPP tracking and converting the solar modules’ DC into grid-compatible AC. Recently, it has also assumed new tasks in supporting the public grid (see also “Inverters and Grid Integration”).
Open circuit voltage
0
0.2
Cell voltage (V)
In order to ensure that it always feeds in the maximum power output, which is dependent on the current insolation and temperature, the inverter automatically searches for the PV generator’s optimal operating point, or “maximum power point” (MPP). The MPP must be continuously tracked to achieve optimum yields. The current and voltage of the PV generator fluctuate widely owing to changes in insolation and temperature, and thus lead to a varying current-voltage (I-V) curve with different MPPs. Modern inverters are designed to always locate the MPP with precision and to follow its movement immediately. Such rapid tracking of the MPP enables the maximum possible output of the PV generator to be utilized.
0.4
0 0.55
In addition to tracking the MPP and converting DC into AC, the inverter performs other critical tasks: It plays a part in system monitoring, and collects and stores information, such as operating data, that is necessary to analyze the efficiency of the PV plant. It also displays error messages and sends them to a computer when required. Furthermore, it monitors the grid connection and checks if this has failed or been switched off. Of late, inverters have also become responsible for controlling fault ride-through and supplying reactive power to stabilize the grid.
P hoto : S M A S olar Technology AG
An inverter is a power converter which converts the DC supplied by the PV generator into AC that has the same voltage and frequency as the grid. If required, this conversion can occur with a specified phase shift, in order to feed reactive power into the grid (e.g. in the event of grid failure) and lend it support. Thanks to state-of-the-art power electronics, converting DC into AC now only incurs minimal losses. The term “grid-tie inverter” (GTI) is also used for the device, as it is specifically geared toward the requirements of the public grid.
0.8
Cell power output (W)
3 Cell current (A)
1.2
Short circuit current
Insight into the manufacture of string inverters
17
Inverters and PV Plant Yield
European Efficiency 100%
η=95.8%
η=91.8%
η=96.4%
η=94.8% η=85.9%
η=96.0%
48%
50%
20% 13% 3%
0%
6%
P5 P10
P20
10%10%
P30
European and Californian Efficiency As a result of converting the DC, losses are incurred which can be relatively high within the partial load range of the inverter (0 to 20% of the rated power), but which are usually less than 5% at the rated output. Inverters usually achieve maximum efficiency at around half the rated output; some of them even reach over 98%. The gradient of the efficiency curve is an important factor in inverter design, as they should be operated in the partial load range for as few hours as possible each year. The time curve of a PV generator’s output in a given location is crucial here. Because the PV generator will only rarely supply its full rated output, it is especially important to know the probability of different outputs occurring.
P50
P100
The European efficiency standard (valid for the type of irradiance level found in Central Europe) is a method which enables different inverters with different efficacy curves to be compared by taking into consideration the amount of time the inverter can be expected to operate at particular percentage loads/levels of solar insolation: EUR = 0.03 η5% + 0.06 η10% + 0.13 η20% η + 0.1 η30% + 0.48 η50% + 0.2 η100% For regions with high solar radiation – approximately 1,200 kWh/cubic meter (m3) annual global irradiance upon a horizontal surface as in southern Europe – Californian Efficiency leads to more appropriate results. According to different conditions of radiation the formula is: CEC = 0.04 η10% + 0.05 η20% + 0.12 η30% η + 0.21 η50% + 0.53 η75% + 0.05 η100%
The inverter in this example has a European Efficiency of 95.5%. The maximum efficiency is 96.4%, but it only operates at this level of efficiency when the inverter is operating at 50% of its nominal rating.
Dimensioning Where moderate solar radiation is prevalent, but full insolation only rare, an inverter which has a much lower rated output that that of the PV generator should be selected. Undersizing the inverter in this way has the advantage that it will operate more frequently in a higher output range, and will thus be more efficient. The disadvantage of this system design is that the inverter will become overloaded more rapidly if the level of insolation is high. Owing to the inherent output limitations, energy will effectively be wasted, as it is not possible to use all the energy generated by the solar installation. The operator must therefore decide whether solar energy yield or economic gain should take precedence. Maximum profitability can also be achieved with slightly undersized inverters, though at times this may be overloaded and energy yield will be diminished as a result. This setup is, however, also less expensive, a saving which can compensate for yield losses in many cases.
P hoto : Tom Baerwald
PV-Generator with polycrystalline modules
18
Inverters and PV Plant Yield P hoto : S putnik E ngineering AG
String inverters safeguard plant yield by minimizing both losses through DC voltage and AC voltage cables.
Owing to the effects of temperature described above, it was initially widespread practice to design AC inverter output to be up to 25% lower than the rated generator output under STC. However, in view of the additional tasks now performed by inverters (e. g. supplying reactive power), it is now recommended that such drastic subdimensioning be avoided. Moreover, the accuracy of weather data has also improved, and it has come to light that short radiation peaks occur more frequently than expected, meaning that the rated inverter capacity should not be “too small” compared to the rated capacity of the solar modules. Working on the basis that a maximum 0.5% of the energy generated should be lost due to output limitations, it is now recommended that an inverter’s rated output should be no more than 10% lower that the STC rated output of the solar generator. Many renowned experts even argue that the practice of subdimensioning inverters should be abandoned completely. With regard to the inverter’s new task of supplying reactive power, the rated capacity of the solar generator and inverter should be roughly the same. Debates surrounding economically viable system design are ongoing.
Autonomous operation The interconnections within a solar generator represent “classic physics”: Connecting individual modules in series allows the voltage to be increased, while connecting strings in parallel augments the current. The inverter input voltage is determined by the number of modules connected in series to form a string, whereas the input current is determined by the number of strings. In each case, the “window” between the minimum and maximum inverter voltage must be taken into account, as must the maximum current carrying capacity. Inverters are connected directly to the public power grid and generally feed three-phase voltage into the low voltage grid. For smaller installations with inverter capacities of up to 4.6 kilowatts (kW) (or 4.6 kilovoltamperes, kVA to be precise), single-phase feed-in is also possible.
Because the inverter is not controlled by the grid, but works autonomously, it also would feed-in power when the grid is switched off, for example in the event of maintenance work. In order to avoid endangering the grid operator’s electricians, the system is required to have a protective circuit which automatically disconnects the inverter from the public grid if its voltage or frequency deviates from the authorized limits. Two automatic load break switches are used to ensure safety. A common design concept for this automatic disconnection device (ADD) is the “mains monitoring unit with allocated switching devices connected in series” (MSD – see “Inverters and Grid integration” ). Grid and plant protection has now become compulsory in Germany.
Thanks to their high efficiency and the excellent quality of power they deliver to the grid, self-commutated inverters have gained a strong foothold in the market. Such inverters contain a microprocessor to create the on and off signals for the electronic circuit breaker. This switching frequency is much higher than the grid frequency. By rapidly chopping the DC supplied by the PV modules, signals are created which best simulate sine function. During pulse pauses, the current is temporarily stored in the input capacitor.
19
Inverters and PV Plant Yield
Central inverter 1.
3. 2.
The PV array consists of several strings of series connected modules. The whole of the installation is served by a single central inverter.
DC AC
4.
5.
Inverters equipped with transformers
Inverter concepts
The use of transformers in inverters simplifies the conversion of AC to match the grid voltage level, but involves magnetic and ohmic losses, and increases the device’s weight. Furthermore, far from operating silently, it draws attention to itself with a low-pitched humming noise. For this reason, high frequency transformers are often used instead of 50 hertz (Hz) models. They are smaller, lighter in weight and more efficient, but require more complex power electronics.
Recent times have seen the construction of ever larger PV plants. As the modules used here are the same as those used in smaller installations, tens of thousands of them are required to build megawattrange solar power plants. The fact that photovoltaic generation involves so many small elements means that, depending on the power rating, several options are available for feeding into the grid.
If the DC supplied by the PV generator is greatly above the crest value of the grid voltage, the transformer becomes technically redundant. In addition, buck-boost converters can be employed to expand the input voltage range of an inverter and adjust it to suit different PV generators. Owing to their higher efficiency, transformerless inverters are now wellestablished on the market. Since removing the transformer also entails the loss of galvanic isolation, a DCsensitive fault protection switch needs to be included. A further disadvantage of transformerless inverters is a slight increase in electromagnetic radiation (electrosmog). These inverters should therefore be installed in a cool, dry place away from living rooms or bedrooms.
20
1. PV generator 2. Generator junction box 3. DC switch 4. Inverter 5. Grid supply
Today, inverters come in so many different sizes that, in principle, each module could be fitted with a customized inverter. Such module inverters essentially enable optimum adjustment to the MPP of each individual module. The AC output of these “micro inverters” can be easily connected in parallel, eliminating the need for DC cabling. Though easy to install on the rear side of the module, the devices have relatively low efficiency and high specific costs. To date, these small inverters are only used in special applications, such as installations with an output of between 3 and 5 kW designed for consumption at source. Alternatively, all module strings can be connected to one sole inverter – a central inverter. This requires that all modules be exposed to the same insolation conditions (in particular: same orientation and pitch, no temporary shading). Central inverters have proven successful in both small and large-scale PV installations. Today, particularly in large-scale PV plants, a variant of the central inverter with three to four inverters in hierarchical order (master and slave) is used.
While insolation is low, only the master is active, but as soon as its upper output limit is reached, as insolation increases, the first slave is switched in. The characteristic curve of the master-slave unit is composed of the curves of the individual inverters, and therefore displays higher efficiency in the lower output range than a central inverter. To ensure that the workload is distributed evenly among the individual inverters, master and slave are rotated in a fixed cycle, which could be that each morning the inverter with the fewest operating hours starts as the master. In addition to module and central inverters, string inverters provide a third option, enabling the MPP of each string to be tracked individually. This solution is ideal where strings receive different degrees of shading throughout the day, causing individual strings to have different operation points. Here, the electricity is fed into the grid by several, independent string inverters. A further variant of the string inverter is the multistring inverter, which combines several MPP trackers in one device.
Inverters and PV Plant Yield
Module inverters 1.
DC AC
1. PV generator 2. Inverter 3. Grid supply 2.
3.
Optimization using individual MPP controllers Given that each module in a string has its own MPP, controlling the MPP of a string is always a compromise which can result in losses. Inverters with separate MPP controllers have recently been developed to get around this problem. These “power optimizers” – sometimes also called power maximizers depending on the company – equip each module with its own MPP controller, which is housed in the module junction box. In this way, each module is able to generate electricity at its optimal operating point, uninfluenced by the other modules to which it is connected in series. This improves the PV generator’s efficiency, enabling it to achieve a higher power yield.
The power optimizers must be suitably equipped to communicate with each inverter, if possible without the need for an additional interface. In addition, the electronic components are required to be able to withstand weather conditions (in particular temperature changes between day/night and summer/winter). Opinions on the actual efficiency of the different systems are divided. Advocates argue that they are particularly useful if a PV generator’s strings are exposed to different levels of insolation in the course of a day. Then, for instance, temporary shading on individual modules no longer impairs the yield of the system as a whole. An enhanced version of the power optimizer was recently launched onto the market as the Module Maximizer. This
device not only tracks the MPP, it also records the output data of a module at any given moment and sends this to the central monitoring system. This allows drops in the performance of individual modules to be detected straight away. Moreover, the Module Maximizer allows operators to disconnect the DC output of individual modules from the central monitoring center if this becomes necessary for maintenance work or in the event of a fire. Specific inverter functions are performed by power optimizers and Module Maximizers, and are thus moved upstream within the module configuration. It remains to be seen whether these developments will actually become widespread, or whether they will remain a niche application.
Single string inverters
2.
DC AC
1. PV generator 2. DC switch 3. Inverter 4. Grid supply
3.
4.
Single-string inverters take a single string of seriesconnected modules. Each string has its own inverter.
21
Inverters and PV Plant Yield P hoto : Tom Baerwald
Manufacture of a central inverter
Inverter lifespan Long-term experience shows that inverters can operate fault-free for ten to twelve years on average before repairs or replacements become necessary. Regular maintenance may increase the lifespan of inverters, but they will never last as long as solar modules (30+ years).
As inverters generate heat while converting DC power to AC power, protection from overheating is crucial.
22
If a central inverter is used in groundmounted installations, it will generally require its own operating room to protect it from dust, moisture and high ambient temperatures. It can, however, also be stored in housing suitable for outdoor use. To prevent any dust from entering, the air cooling system is replaced by a liquid cooling system, meaning an operating room is no longer necessary.
P hoto : R efusol G mb H
Inverters are used in many different environments: both indoors and outdoors and in almost all climate zones. The most important factor limiting where an inverter may be installed is the maximum permissible temperature at rated power. Where the operation of the inverter or the ambient temperature could cause this to be exceeded (e.g. if the inverter is installed in an uninsulated roof structure), active cooling becomes necessary. However, the use of ventilators entails further risks, for example when inverters are installed in agricultural buildings. Here, if incorrectly installed, the ventilator can draw grain dust or ammonia vapors into the inverter, which can restrict ventilator operation or induce corrosion. In order to increase service life, particular attention must therefore be paid to ensuring that an inverter’s individual components cannot overheat. In addition, they must be kept free from dust, damp and aggressive gases.
Inverters and Grid Integration
Inverters and Grid Integration Integrating increasing amounts of solar energy into the public power supply puts various demands on PV plants. For example, special protective devices are required to prevent the risk of danger in the event of mains interference. The more PV plants feed into the public grid, the greater the demands placed on the grid services that they must perform. This is why inverters are incorporated into the grid management system.
Thin-film roof-mounted installation boasting an output of 1 MW and equipped with string inverters in Bitterfeld (Germany) P hoto : R efusol G mb H
23
Inverters and Grid Integration
High demands for feeding in power Guidelines and standards regulate exactly how PV plants should be connected to the public grid, which gives rise to two highly important requirements. Firstly, when solar power is fed into the grid the power quality of the grid should not be reduced. Secondly, personal safety must be ensured in the event of mains interference. Another requirement has also recently gained importance: Instead of shutting down at the first sign of a fault (fault ride through), PV plants should support the power grid and perform gridrelated control functions. The requirements for power feed-in are clearly defined: The grid requires sinusoidal AC with stable voltage and frequency, and the harmonic component limits are regulated in guidelines and standards. Modern inverters meet these power quality requirements, yet in some cases limits may be exceeded. Voltage and frequency stabilities are high in the fully-developed, close-meshed grid supplied by large thermal power stations, and solar power can usually also be injected without problems, even in large quantities.
P hoto : Tom Baerwald
Substations collect decentrally generated solar energy and transform it into a higher voltage level before it is transported to the centers of consumption.
The further away the feeding point from large power plants, the greater the requirements that are placed on grid feedin. As a general rule, when electricity is drawn from the grid, the grid voltage falls, and when power is fed in it increases. Particularly when PV plants feed into rural grid structures or grid branch lines, this can cause an increase in voltage that exceeds the specified limits. When a large amount of energy is consumed, the voltage in these weak grid spurs decreases, meaning that the act of feeding in decentralized solar power supply counteracts this decrease in voltage and, in turn, supports the grid. Mea sures need to be taken to inhibit excessive increases in voltage during periods in which an especially high level of power is being fed-in and very little is actually being consumed. A further consequence is that – particularly when grid feed-in is high and consumption is low in a particular area of the grid – the flow of current can reverse in the power grid, and not all grids are prepared for this yet.
Disconnection devices The grid operator stipulates that a protective device be used between the power generating plant and the grid, which can disconnect the plant from the grid when necessary. Its primary function is to ensure personal safety, because if the grid is shut down to carry out repair or maintenance work, power generating plants could continue to feed energy into the grid and put the safety of staff at risk. With smaller PV plants, this task is performed by an ADD or a manual disconnection device to which the grid operator has permanent access. An ADD recognizes grid failures and cutoffs, as well as changes to voltage and frequency which exceed the authorized limits, and disconnects the PV plant from the grid.
P hoto : Tom Baerwald
Laying cables during the installation of a ground-mounted system
24
Inverters and Grid Integration
Possible grid disturbances
0
0
Voltage 0 Time (s)
0.02
0.04 0 Time (s)
Some power supplies, such as those used in older computers but also in other recent appliances and compact fluorescent light bulbs, cause changes in sine waves.
Until 2004, only the use of an MSD as an ADD was permitted in Germany. The MSD measures grid impedance and is able to recognize power failure and cutoff on the basis of impedance jumps. Since 2005, other grid monitoring methods have been authorized: These include evaluating the harmonic components, measuring the deviation of grid frequency and three-phase voltage monitoring. An external grid and plant protection device has now replaced the use of both MSD and ADD. As of January 1, 2012, this has been officially enforced by the “VDE Application Guide VDE-AR-N 4105” (Generators connected to the low-voltage distribution network – technical requirements for the connection to and parallel operation with low-voltage distribution networks). The grid and plant protection device monitors all relevant grid parameters, isolating the PV plant from the grid if excessively high or low voltages or abnormal fluctuations in frequency occur at the feed-in point. The PV plant is automatically reconnected to the grid once the voltage and frequency have returned to acceptable levels.
0.02
0.04 0 Time (s)
When “capacitive” power appliances are switched on, brief disturbances arise. Battery chargers are examples of capacitive loads. But these loads have to be very great indeed for the disturbances to have an impact.
Static and dynamic support In Germany, large-scale PV plants which feed into the medium-voltage grid must provide certain grid services in accor dance with the country’s Medium Voltage Directive (Mittelspannungsrichtlinie). In addition to a device facilitating power reduction, these include static and dynamic grid support. Control algorithms are therefore developed for inverters in order to control voltage and frequency fluctuations. Adherence to the Medium Voltage Directive has been compulsory since January 1, 2009, although transitional periods apply. Comparable provisions are contained in the Low Voltage Directive (Niederspannungsrichtlinie), meaning that even small and mediumscale PV installations are now also required to perform grid services. The performance-reducing device is primarily designed for PV plants with outputs of more than 100 kW. These have to be fitted with a technical device designed to reduce feed-in capacity, such as a ripple control receiver and a device that monitors the current power feed-in. PV plants with outputs of between 30 and 100 kW must be equipped with a simple feed-in management system, with a device that reduces feed-in capacity being sufficient. Operators of PV plants with outputs of less than 30 kW have the choice of either using a simple feed-in management system or limiting the feed-in capacity at the grid connection point to 70% of the maximum module output. This means that peak power outputs are capped at a fixed rate. Regardless of their outputs, existing plants have to be suitably upgraded in case the generator’s rated output exceeds 30 kWp.
0.2
0.4
A large power consumer can put such a great load on the grid that voltage drops. Inverters can only compensate for such disturbances if the devices can store electricity.
Static grid support is required when grid voltage rises or falls slowly. Support is provided by supplying reactive power and limiting active power dependent on the frequency. Dynamic grid support is predominantly required when voltage dips occur in the upstream high-voltage grid. The PV plant should not then shut down immediately, but should remain on the grid for a time (fault ride through, FRT) and feed-in reactive current to support the grid voltage dynamically. Only when the grid ceases to function for several seconds is the PV plant shut down for safety reasons. Data loggers, which in addition to mea suring grid parameters, control real power and feed-in reactive power where necessary, have recently been put to use to support grid services. They enable ripple control receivers to be connected and log the resulting reduction in power. Manufacturer-independent monitoring devices are another way of monitoring and analyzing the various inverters within a plant. The VDE-AR-N 4105 is also intended to contribute to avoiding frequency stability problems in the power grid. For example, it states that, in future, photovoltaic installations will not strictly need to be completely disconnected from the grid upon reaching an overfrequency of 50.2 Hz, but rather that there will be a smooth transitional zone between 50.2 Hz and 51.5 Hz, within which the installation may continue to feed in power at a reduced capacity. This new application guide also affects existing plants with outputs of over 10 kWp, which need to be upgraded accordingly. The different
25
Inverters and Grid Integration
Voltage levels in the German power grid Ultra-high voltage 380/220 kV
medium voltage 20 kV
high voltage 110 kV
low voltage 0.4 kV
Consumer: Industy
Transformer substation
Transformer substation
The power grid comprises different voltage levels. Overland transmission lines work at extra-high voltage but this voltage level is reduced from high to medium and finally low voltage as the power is transported to consumers. In the past, power was only ever transmitted in one direction from centralized (large-scale)
cut-off frequencies of individual inverters are distributed stochastically in such a way that all inverters synchronize with the cut-off point of one single inverter. Since July 1, 2011, static grid support will be prescribed by law in Germany. This applies to all inverters that feed into the medium and low voltage grids which have an output of 3.68 kVA or above (230 V x 16 amps, A). The transitional period expired on January 1, 2012, so practically all PV plants that are connected to the grid will be required to perform this grid service. These increased requirements on systems technology – particularly inverters – contribute to stabilizing the power grid and bring with them the advantage that it will now be possible, even in weak grids, to install a far greater amount of PV capacity before expansion of the grid is required.
Transformer substation power plants to (decentralized) consumers. Due to the decentralized production of renewable energy, however, the flow of current can reverse and the power grid needs to be appropriately prepared for this. By feeding in reactive power, PV power plants are able to contribute to grid stabilization.
the public grid, can play a decisive role in this and can complement the grid integration of photovoltaic systems. It is also intended to encourage on-site consumption (for roof-mounted installations of up to 500 kWp). Decentralization and consumption at source Using intelligent control engineering, a variable, virtual, large-scale power station could be developed in connection with decentralized feed-in systems and electricity consumers. As elements in this power plant, PV plants would contribute to reducing the purchase of electricity from the public grid. Moreover, PV plants could improve supply security through short-term island operation.
VDE AR-N 4105 also aims to improve load balance, as this can become unbalanced during single-phase feed-in from a multitude of power generators. There is now an unbalanced load limit of 4.6 kVA per phase in place, even in the event of faults. Only a maximum of 13.6 kVA per PV plant can be connected to the grid with three single-phase feed-in inverters. As a result, three-phase feed-in inverters are increasingly being used.
In future, inverters will take over more and more grid management tasks and provide energy services. In addition to stabilizing voltage and frequency, these include controlling the power factor and the targeted production of harmonic components to improve grid quality. For this reason, bidirectional network interfaces are required to enable the necessary communication and to link the large number of decentralized suppliers and consumers together in “smart grids”.
Using power from a low-voltage grid offers great potential for conserving and displacing power, which can be optimized by decentralized feed-in systems. Micro grids generating their own power, which are connected to one another by
Due to the decentralized nature of solar power generation, it is obvious that users generating power should themselves consume as much of this as possible at source. This reduces grid feed-in and the need to transport power over great distances.
26
Consumers: Towns, cities and communities
In an average household, 20-30% of energy is consumed at times when solar power is generated. Simple measures could be used to increase this proportion by a further ten percentage points, for example by logging consumption as well as generation using the automatic plant monitoring system, which will compare both graphically. Users could then better adapt their consumption to match generation and maximize their own consumption of the solar power. With an energy manager, the inverter could be fitted out so that it automatically switches on individual household appliances (washing machines, dishwashers, tumble dryers, etc.) as soon as enough solar power is generated. These appliances would be equipped with remote-controlled sockets and their performance data stored as profiles. The PV plant and the power network in the home would thus be unified, and electronic appliances would be supplied with either pure solar power or a mix of solar and grid power depending on insolation. In Germany, the on-site consumption of solar power was subsidized as part of the Renewable Energy Sources Act (EEG) between January 2009 and March 2012. Only energy consumed concurrently with its production, i. e. the actual energy that was not fed into the grid but was directly consumed in close proximity to the PV plant, was considered to be for “own consumption”. It was not possible to balance out yield produced throughout the year with annual consumption. In order to
Inverters and Grid Integration P hoto : P uget S ound E nergy
P hoto : F irst S olar
Maintenance work on transmission lines in the USA
As one of the first utility-scale PV projects in the United States, the 21 MW Blythe Solar Power Project in California includes 350,000 thin-film modules. It serves the needs of approximately 6,000 local homes.
check concurrency, a production meter was required in addition to a reference and feed-in meter. The actual on-site consumption was calculated from the difference between production and feed-in. In the current version of the EEG, the on-site consumption bonus has been removed and feed-in tariffs for solar energy have plummeted to such low levels that in many cases remuneration is lower than the net price for purchasing electricity. Even without subsidies, this makes the on-site consumption of power worthwhile. If feed-in is single-phase but individual consumers have a three-phase connection, differences will arise which impact badly on the evaluations of own consumption. Three-phase feed-in is, therefore, an advantage. The next step is to bring together energy consumption control and battery storage – either as a stationary battery bank or in mobile format in an electric vehicle. Conventional batteries are only of limited suitability for this purpose because high storage losses and low efficiency lead to costs of 20 to 30 euro cents per kilowatt hour saved. These costs can be reduced by higher consumption of energy at source, improved load displacement and, above all, by increased conservation.
A view on the United States Solar electricity, though making up only a small fraction of the USA’s power generation, is cementing its place as a longterm source of energy. With this progress comes the need to re-imagine the future of the electric grid. In the United States, many utilities and grid operators are doing just that as they grapple with scenarios that will require a more dynamic act of balancing the supply and demand. California presents the best case study. Eleven years after California established a renewable energy generation goal and set an example for the rest of the country, the state is just now starting to see a large infusion of solar energy going into its grid. In regulations and policy planning, the state’s utilities and the grid operator, the California Independent System Operator, have been carrying out studies and technology trials to figure out how to manage the grid when it gets a big surge of solar energy for part of the day and when solar power plants go offline because of cloud cover. The use of energy storage could help even out the power flow. Integrating more advanced functions into inverters, on the other hand, is now a key way to help manage the growing amount of solar energy in the grid. Functions such as low-voltage ride through, reactive power injection, over-frequency response and ramp-up control are either required or considered for interconnecting solar power projects in the transmission and distribution networks.
These functions, while not new in their existence, are new in the United States because the country is a younger solar energy market. According to GTM Research, preliminary data show that by the end of 2012, the country reached a cumulative PV installation of 7.1 DC GW. This number is small compared to what Germany could install in one year. According to the largest utility in California, penetration is currently low and the units do not have significant impact on the system so interconnection can be made relatively easily. But at a high distributed generation penetration, and for large units, the distributed generation impact may be much higher and/or the grid may not have sufficient operating margin to cover for the renewables if a large number of them tripped off unnecessarily due to a major system disturbance. Several large solar power plants are under construction in the western USA that will start to drive up the solar content of the electric grid, most notably in California. The country had 2.1 DC GW of utility solar projects under operation at the end of the third quarter of 2012. GTM said that there was another 10 DC GW that were under contracts with utilities but had not been built.
27
Inverters and Grid Integration P hoto : F irst S olar
Nearly 775,000 thin-film PV panels were installed for the 48 MW Copper Mountain Solar plant in Nevada, USA. The facility generates electricity to power about 14,000 average homes.
Large-scale solar development is happening mostly in the western USA, particularly in California, Arizona and Nevada. This includes a 250 AC megawatts (MW) project in San Luis Obispo County in central California, and that project is close to another 550 AC MW solar farm. Two power plants totaling 579 AC MW are being built in southern California, and in Arizona a 290 MW project is under construction. Advanced features An inverter’s core job is to convert the DC from solar cells into AC, but increasingly they are now expected to monitor the grid’s heath closely and react accordingly. The Institute of Electrical and Electronics Engineers (IEEE) has undertaken the task of modifying the 1547 standard for interconnecting renewable energy generation with the electric grid. Standard setting is a long, multi-year process, and efforts are underway to speed up the process for connecting PV generation systems given PV technology has surged ahead of other solar technologies to dominate the market. Voltage and frequency regulations are the two big issues for keeping the grid working properly. The grid in the USA operates at 60 Hz. Transmission lines generally run from 138 kilovolts (kV) to 765 kV, whereas distribution lines run to 4 kV.
28
The IEEE 1547 participants have been looking at whether to mandate certain technologies for voltage and frequency regulations, the jobs of which would or could then fall on the inverters. Until now, technical standards have largely focused on making interconnection fairly easy and inexpensive, given the low saturation of solar energy in the grid. As solar increases its share of the power mix, however, more sophisticated control of its impact on the grid will be needed. One of the more advanced inverter features, low-voltage ride through, seems certain to be included as part of IEEE 1547 to deal with the effect of a greater amount of solar power flowing into the grid. The function keeps the inverters pumping solar power into the grid even when the voltage of the grid drops and becomes instable. The idea is not to shut off all the PV systems when the voltage dips because, according to micro inverter developers, doing so is not necessary and may contribute to more instability of the grid. If a large amount of solar energy production goes off line unexpectedly, then the utilities will have to scramble to make up for the shortfall, or else they risk a blackout. Low-voltage ride through does somewhat conflict with an existing IEEE 1547 requirement that all inverters are turned off automatically when they detect certain voltage or frequency levels that deviate from the norm. Resolving the differences in these two functions will be needed in the standard-setting process.
While the IEEE 1547 process moves forward, some grid operators and utilities have already adopted the low-voltage ride through function for PV systems as requirement it for transmission line interconnection, for example. The California Independent System Operator, for example, requires it for transmission line interconnection. Meanwhile, one of the largest utilities in the United States based in San Francisco, uses inverters with low-voltage ride through capability in its own PV power projects connected to its distribution network. Reactive power injection is another function that helps to keep the grid humming along. Its presence is necessary to keep the voltage at desirable levels in order to deliver active power – energy measured kilowatt hours – through transmission and distribution lines efficiently. Utilities typically use a bank of capacitors to supply reactive power, measured in voltampere reactive (VAR), to keep the voltage level up when a big load of power is brought online. Inverters can provide reactive power injection, too, and usually through the point of interconnection, though solar power plant owners do not really have an incentive to do so. That is because utilities do not usually pay for reactive power in the power purchase agreements they sign with solar power project developers. If a solar farm is sending reactive power, then it is not feeding active power into the grid. Although compensation is a big issue, some developers could still offer reactive power injection as a way to hopefully speed up their interconnection agreement negotiations with utilities.
Inverters and Grid Integration P hoto : S iemens AG
Installation of a power converter valve module for use in a high voltage direct current (HVDC) transmission system
Inverters also can provide over-frequency response by dialing back the injection of active power to bring the frequency back to the ideal 60 Hz. And increasingly, power plant developers are asking for ramp-up control. The rampup function is designed to gradually bring the solar power plant online. Power plants in general have a ramp-up process to increase their output until they reach full production. This process needs special monitoring and control with a solar power plant because solar power production is not as steady as a fossil fuel power plant. While adding the ramp-up control to inverters is not a difficult task, creating the ramp-down control is much harder. The use of energy storage to accompany the ramp-down process would be necessary, and that adds additional cost.
Making them work for a complex grid Adopting more advanced inverter technologies will be more challenging in the United States than in countries such as Germany, which is not only smaller but also has a national solar policy and grid management system. The United States, on the other hand, has a far more complex electric grid and over 3,200 utilities. In fact, the grid in the continental USA is composed of three regional grids that are overseen by eight regional grid reliability organizations and one national group, the North American Electric Reliability Corporation.
That complexity makes it difficult to set technical standards and mandate consistent best practices nationwide to manage the growing solar power generation. Making sure any standards leave room for configuring inverters to fit the needs of grid operators and utilities is key. At the same time, adding more inverter functions will also make solar power projects and grid operations more complex and costly. Currently, there are national standards to make sure inverters from different manufacturers can communicate and work well with one another and with the equipment a utility would use to manage the grid. In order to utilize the more advanced features, the distribution system will become much more complicated in design. Costs and benefits of implementing the additional features are also needed to be weighed.
The grids of the future are set to be smart: Intelligent technology ensures that energy systems are equipped with information and communication technology to control the feed-in of decentrally generated energy. P hotos : S iemens AG
29
Storage and Energy Management
Storage and Energy Management The development of efficient power storage systems with high lifespans is essential for photovoltaics to become a stable mainstay of electricity generation in spite of seasonal fluctuations in the amount of solar power generated. The effects of short-term fluctuations from one hour to the next are lessened by load shifting and solar heating. Meanwhile, decentralized energy management is gaining in importance as much as decentralized power production. To ease the burden on the grid, as much solar power as possible should be consumed on site or in the immediate vicinity of the location in which it is generated. An intelligent management system for battery power plants is indispensable for integrating storage systems into both private and large public grids. P hoto : Tom Baerwald / Younicos Technologie z entrum
30
Storage and Energy Management P hoto : Tom Baerwald / BA E Batterien G mb H
Lead-acid gel battery
Surpluses persist despite on-site consumption
Subsidizing storage In Germany, solar power storage systems are set to be subsidized by an investment grant. It has been reported that in order to receive funds, the storage systems must contribute to easing pressure on the grid, especially that created by solar power production. Grants of between 2,000 and 3,000 euros per storage system are anticipated and a total of 50 million euros is set to be made available for the subsidies. The exact date of the introduction is yet to be decided (as of March 2013).
P hoto : Tom Baerwald / Younicos Technologie z entrum
Photovoltaics can only generate power during the day and yields are significantly higher in the summer. In order for PV plants to make a considerable contribution to the power supply, the further increase in solar power generated must be underpinned by an expansion in storage capacity. As the daily and seasonal fluctuations in output are each compensated for by different forms of storage, a twopronged approach, comprising a mixture of small, decentralized short-term storage systems and large seasonal storage systems, is required to extend storage capacities. Differentiation must also be made between storage systems that maximize benefit for plant operators (i. e. systems that are charged when the solar power cannot be consumed immediately on site) and those which are beneficial to grid operators (i. e. systems that are only charged when there is a surplus of power in the grid).
The on-site consumption of solar power was subsidized in Germany between January 2009 and April 2012. The strong growth of photovoltaics in Germany has now led to a situation where excess solar power is produced in some regions during the middle of the day. Power generation is becoming regionally concentrated during specific periods. Given that, in most cases, the power supplied by the PV plants dramatically exceeds the demand of nearby consumers, it is impossible to avoid creating such a surplus simply by introducing provisions for on-site consumption. As the number of new PV installations increases year on year, the number of regions where more solar power is generated than consumed is also set to rise.
Due to the relatively high costs of storing power, it is vital that as much as possible is consumed immediately and decentrally. This means that the importance of onsite consumption will continue to grow.
Simulating sudden drops in load, short circuits or changes in the weather ensures that storage systems are also able to function safely in extreme conditions.
31
Storage and Energy Management
Potential use of solar power in private households 1. 1. Solar installation 2. Energy management 3. Consumption devices 4. Storage system (battery) I.
3. In view of the steadily falling feed-in tariffs, it is becoming increasingly important for installation owners to consume as much solar power as possible in their own homes. On-site consumption (I.), which can be increased by means of load shifting, takes precedence over storage (II.), as this entails relatively large losses. Solar power is only fed into the grid when the battery is fully charged and the consumption devices do not require power (III.). Purchasing relatively expensive electricity from the grid (IV.) is the least favorable option, and should only be considered if the PV installation is supplying too little power and the battery is run down.
Storage media The portion of solar power that can neither be absorbed by the grid nor used directly on site needs to be temporarily stored. Batteries are the primary contenders for this task, as they have proven their worth over decades of use and can be employed in decentralized systems. Owing to topographical restrictions in Germany, cross-regional storage in reservoirs (pumped storage hydroelectric power stations) is only possible to a very limited degree. Compressed air energy storage represents one alternative technology that, in principle, holds great potential, but its efficiency is still in need of improvement.
5. Consumption meter 6. Feed-in meter 7. Energy utility 8. Power grid II.
2.
4.
III. 7.
IV.
00123467
8.
00123467
5.
6.
Source: Volker Quaschning, Regenerative Energiesysteme, 7th edition, Hanser Verlag, Munich2011
Converting solar power into chemical energy (e.g. by means of electrochemical hydrogen generation) incurs relatively high losses, but does bring with it the advantage that energy can be stored for long periods of time. Solar hydrogen can be converted into either electricity or heat and can also be used as fuel, directly substituting petroleum products. Converting hydrogen into methane would achieve an even higher energy density and thus tap into an even greater storage capacity. In this case, the efficiency of converting the energy does drop somewhat, but this would still be acceptable given that free sunlight is the energy’s source.
The latest developments in technology do not allow us to foresee which storage systems will triumph in the long term. The most likely scenario will involve a mixture of small, distributed, short-term storage systems and large, seasonal storage systems. Ultimately, if the intention is to make photovoltaics a mainstay of German power supply, a solution must be found to store the surpluses generated in summer for use during winter.
Several storage technologies are needed to compensate for fluctuations in the amount of solar power generated. Small quantities of power are stored in batteries in the short term, while large quantities are stored in the form of hydrogen or methane in the long term.
1 year 1 month
Pumped storage power plants Compressed air energy storage
1 day
Synthetically produced methane
Hydrogen
1 hour Batteries
1 kWh
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10 kWh
100 kWh
1 MWh
10 MWh
100 MWh
1 GWh
10 GWh
100 GWh
1 TWh
10 TWh
100 TWh
S ource : Zentrum f ü r S onnenenergie - und Wasserstoff - F orschung Baden -W ü rttemberg ( Z SW )
Storage duration and storage capacity
Storage and Energy Management
Batteries The only type of instant storage currently available is that of secondary electrochemical cells, generally known as (rechargeable) batteries. However, the un avoidable phenomenon of self-discharge in batteries means that they are only suited to storing solar power for short (from a few hours to a few days) and medium (a few weeks) periods. Moreover, the lifespan of a battery is limited by its cycle life, not forgetting that the number of possible charge cycles falls as the depth of discharge increases. The battery therefore needs to be protected against over-discharge. In lead-acid storage batteries, for example, full discharge converts the lead sulfate into a crystalline form which is only partly dissolved when the battery is charged again, causing permanent damage. What is more, the capacity that can be extracted from an accumulator decreases as the discharge current becomes more powerful. Lead-acid storage batteries are cheapest and are therefore most frequently used. They are filled with an electrolyte of dilute sulfuric acid, meaning that if the final charge voltage is exceeded, gassing may occur. When this happens, oxygen forms on the positive electrode and hydrogen on the negative. These two gases then form explosive oxyhydrogen. Gassing also leads to the gradual loss of water, which needs to be regularly refilled. Overall, the cycle life of lead-acid storage batteries is relatively low.
In order to increase its lifespan, the electrolyte can be thickened using additives to form a gel. Lead-acid gel batteries can be assembled fully sealed, meaning that they are leak proof. In this case no gas is able to escape, but lead-acid gel batteries may dry out as a result of gassing. A special charge controller is therefore necessary to manage the final charge voltage very precisely. Lead-acid gel batteries have double the lifespan of lead-acid storage batteries with liquid electrolytes. They allow around 2,000 cycles, provided no more than 30% of the capacity is discharged each time. If 50% of the capacity is drawn on a regular basis, lead-acid gel batteries will need to be changed after around just 1,000 cycles. Lithium-ion batteries achieve markedly higher cycle lives. If discharged and recharged daily, they can reach a lifespan of 20 years, equating to 7,000 charge cycles. Their special features include high energy densities and low self-discharge rates. They also withstand high charging currents, and can therefore be charged very quickly. These advantages currently make them ideal storage batteries for homes and electric cars. Prices for such batteries are still high, however, and will not fall until mass production levels are achieved.
Both types of storage battery (lead-acid and lithium-ion) share the common feature that their electrodes undergo chemical conversion during charging and discharging, and therefore slowly degenerate. Redox flow batteries avoid this. A relatively new development, these batteries combine the properties of the accumulator with those of the fuel cell. The reactants are each dissolved in an electrolyte and circulate separately. These two electrolytes are pumped through a cell in which ions are exchanged. This cell is divided by a membrane that only allows ions to pass through it, thus preventing the reactants becoming mixed. The electrolytes that store energy in redox flow batteries are kept in separate tanks. As a result, the quantity of energy and the output can be scaled independently of one another. Redox flow batteries are characterized by their high efficiency and long life expectancy. The capacity of the redox flow storage systems that are shortly due to be launched on the market lies between 3 and 13 kWh. Apartment buildings and commercial establishments require larger units, providing an opening for those redox flow batteries that are currently offered in 200 kWh modules. Here, additional modules can be added to increase the capacity. As both lithium-ion batteries and redox flow batteries are still at an early stage of development and are relatively expensive, the lead-acid battery is still the most economical way to store solar power, despite its short cycle life.
Lithium-ion battery Charge
+
Redox flow batteries
-
DisCharge Li+ Li+
Li+
Li+
Al
Lithium
Cu
Oxygen
Metal (cobalt, nickel, manganese)
Carbon
Electron
Separator
During charging, the graphite absorbs electrons, while the metal oxide at the battery’s other pole releases electrons into the external power circuit. In doing so, lithium ions flow from left to right (,) and settle between the layers of carbon. The entire process is reversed during discharging (%). While the separator is permeable to the lithium ions, it does not allow the negatively charged counter-ions to pass through it, thereby preventing self-discharge. The graphite and metal oxide electrodes are often made in the form of foil. An electrolyte is placed between them, through which the lithium ions are able to flow. Lithium-ion batteries come in many forms, which vary in terms of the materials used to make the electrodes, separator and electrolyte.
33
Storage and Energy Management
DC and AC storage system Solar installation
Inverter
= = =~
In an AC system, the battery is separately connected to a house’s alternating current grid via an inverter and direct current converter.
Production meter
Bidirectional meter
123456
Battery inverter Charge regulator
DC converter
123456 Charge regulator
= = = =
Battery
Overall, storing solar power in batteries is a relatively expensive enterprise. It currently costs roughly as much to store a kilowatt hour of electricity as it does to generate it from sunlight. The specific costs of storage (in euro cents/kWh) are not the sole criterion, however. If the goal is to operate a battery system as profitably as possible, cycle life, the output of the PV plant and household energy requirements must also be considered. In order to incorporate batteries into a PV system, special storage systems are required which consolidate the storage battery with the necessary power electronics. These have only recently become available on the market. They not only differ according to battery type, but also based on how they are installed. Some systems are incorporated into the house’s AC circuit, while others are integrated into the PV plant’s DC circuit. Integrating the system into the AC circuit has the advantage that as much additional capacity as desired can be added at a later date, irrespective of the PV capacity installed. A battery inverter is needed in addition to the PV inverter, meaning that relatively high outlay is required, but such systems come with the extra advantage that power from the grid can be fed into them more easily, as the battery inverter operates bidirectionally. Incorporation into the DC circuit also has two advantages: the system costs are lower and the storage efficiency is higher. This method requires the installation of a PV inverter and a pair of DC/DC con-
DC connected PV battery systems
Consumer
Public grid Inverter
=~
= =
Storage systems
34
Public grid
Solar installation
123456
= ~
DC converter
AC connected PV battery systems
Consumer
Battery
verters. They set the voltages of the PV system and the battery at precisely the level that is best for the inverter. To simplify matters, they can be installed in the metal cabinet that houses the battery. Despite the high investment costs involved, battery capacity should be selected to enable as much solar power as possible to be consumed on site. By way of example, for a 4 kW plant and annual energy consumption of 4,000 kWh, a capacity of 6 to 7 kWh is recommended if the quota of on-site consumption is intended to reach 70%. A quota of over 30% will be virtually impossible to achieve without using storage, unless the solar power is also used to heat water. Combinations of photovoltaics, heat pumps for water heating and intelligent energy management, for instance, can achieve on-site solar power consumption rates of up to 50%, even without storage systems. Of course, checks should always be made to examine whether or not solar thermal installations will represent the most economical solution for the actual needs and conditions of the site. Maximizing on-site consumption without considering the consequences must, however, be avoided. Care must always be taken to ensure that consumption only increases in order to raise the quota of on-site consumption and that power is not used arbitrarily and unnecessarily, as this would be counterproductive in terms of energy efficiency. On the other hand, replacing fuel, by, for example, using energy-saving electric vehicles on a large scale, would be a highly welcome development.
123456 ( Production ( meter
123456 123456
Bidirectional meter
In a DC system, the battery is connected between a direct current converter and the original inverter. A fundamental decision when choosing between storage concepts is whether to use a DC- or AC-connected system. An intelligent measuring system is needed to record the quantities of power which are generated, stored, consumed on site or fed into the grid. A production meter is only required for DC-connected systems where it is necessary to prove the quantity of solar energy generated, e.g. in the event of bonuses for on-site consumption or partial remuneration. AC systems may be required to be fitted with a meter (not shown) attached to the battery system showing that it feeds solar power into the grid instead of charging its battery using grid power.
Heat accumulators and heat pumps One very simple way of storing energy is to store heat. As buffer storage is already available in some houses in the form of hot water tanks, surplus solar power could also be converted into heat by conducting it through an immersion heater inserted into the storage tank. As long as the production of solar power is significantly more expensive than producing hot water, this will remain a very wasteful use of energy. Nevertheless, falling solar energy generation costs combined with rising prices for raw materials will slowly close this gap. A far more efficient application of surplus solar energy is in a heat pump. If this pump is capable of generating 3 kWh of heat from 1 kWh of electricity, 1,600 kWh should theoretically be sufficient to heat a well-insulated house with a living area of 120 m2 and heating requirements of 40 kWh/m2. This calculation is unrealistic, however, as supply and demand do not coincide: In winter, when the greatest demand is placed on the heat pump, the PV plant will furnish the least electricity.
Storage and Energy Management P hoto : Tom Baerwald / B osch - power-tech
Energy management It is considerably easier to generate solar power than to store it, as this entails relatively complex installation procedures and unavoidable losses. In order to complement the storage options, as much energy as possible must therefore be consumed on site and the conditions for marketing the power must be made as favorable as possible. This situation will then replace the current practice of unreservedly feeding power straight into the grid. If the statutory feed-in tariffs were to be abolished, or sink so low that it became unviable to feed all the solar power generated into the grid, this custom would die away. Grid feed-in will then only be sensible under certain circumstances and should only be considered if other options are not available.
Inverter system with an integrated energy management system for optimizing on-site consumption
The conditions are somewhat different if the heat pump is used to provide cooling via an air-conditioning unit. In this case, the periods of energy production and consumption do correlate if power from the photovoltaic plant supplies electricity for heat pump cooling during the summer months. In the USA, for example, heat pump cooling is already widespread.
Load shifting can help to increase on-site consumption rates. For example, large household devices that do not require power at a given time might only be switched on when solar power is in plentiful supply. Washing machines, tumble driers and freezers can thus contribute to improving the coordination between demand for power and supply. These energy management systems need to succeed in changing the consumption patterns of the average consumer, i.e. to drive them away from simply using household power at any time at the push of a button. They must clearly indicate the costs per
Irrespective of their intended use, heat pumps are not suitable for storing energy over the long term, but merely represent a component of good energy management.
Photovoltaic back-up heating 1. Solar installation 1. 2. Energy management 3. Consumption devices 4. Heat pump 5. Combi heat storage tank 6. Shower 7. Heating system 8. Consumption meter 9. Feed-in meter 10. Energy utility 11. Power grid 3.
10.
6.
I.
III.
2.
4.
00123467
8.
00123467
II.
5.
7.
11. 9.
Source: Volker Quaschning, Regenerative Energiesysteme, 7th edition, Hanser Verlag Munich 2011
kilowatt for each device at a given moment and ideally offer alternative operating times within the shortest possible time frame. Favorable sales conditions will become possible if the tariff for purchasing power from the grid increases while the solar power produced on house roofs becomes cheaper at the same time. This power can then be sold to neighbors in close distance at a price below the electricity tariff, as the short distances will mean that grid fees are waived. Only once these two channels have been exhausted should solar power be used in hot water tanks or heat pumps. Using solar power for heating means using solar energy under its value. This is why it ranks third in the hierarchy of solar power exploitation. Given the fact that storing power in batteries will remain relatively expensive for the foreseeable future, it should be avoided if at all possible. If several other possibilities for use are in place, only a small battery capacity will be required. As a last resort, feeding power into the grid remains an option. This would struggle to contribute to PV plant profitability, however, as solar surpluses are produced by many PV installations simultaneously. Increasing on-site consumption through load shifting and solar heating, selling power, storing it, and feeding it into the grid are the options available to the energy management systems of the future. If possible, these systems should be able to independently decide on which type of use would be most beneficial to PV plant profitability at which times, and to activate consumption devices and storage systems as required. This concept demands a great deal of the systems technology, which will inevitably change over time. Gradually inverters will be replaced by energy management systems. Developing these is the task that now lies ahead.
As solar power generation becomes increasingly less expensive, it may be practical to utilize this power not only to operate household devices (I.), but also to back up the heating system (II.). Surplus power can then be fed into the grid (III.). However, since remuneration for this is becoming ever lower, the option of producers marketing their own electricity and thus creating a distributed power supply is fast developing – but this requires an appropriate legislative framework.
35
Storage and Energy Management P hoto : N ext E nergy
Development of new battery systems: initial tests in a research lab
Power storage has always been a key requirement to achieving self-sufficient energy supply in locations situated away from the grid. Short-term power fluctuations, caused for example by clouds passing overhead, have particularly negative effects on these stand-alone systems and appropriate storage capacity must be made available to counterbalance this. For instance, batteries capable of storing 250 kW are required to compensate for unexpected power fluctuations in solar plants with outputs of 1 MW. The batteries used must also be capable of discharging quickly. Lithium-ion batteries, and in particular those with medium energy densities, have been found to be highly suitable for this. The solar power supply of stand-alone systems therefore makes additional demands on energy management. Load shifting plays a vital role in this area.
Storage costs Outlays for storage are determined by the system’s investment costs and life span. When calculating these, focus is placed on the capacity-related costs (euros/kWh) as opposed to the performance-related costs (euros/kW), with the efficiency of the battery system also playing a role.
P hoto : Tom Baerwald / H O P P E C K E Batterien G mb H & Co. KG
The lifespan of batteries used to store solar power should ideally be at least as long as that of PV plants, i.e. 20 years. The desired lifespan of the first mass produced batteries is ten years. Traction batteries, which are currently being developed at breakneck speed for the automotive industry, have much shorter lifespans of between five and eight years, making them less suitable for storing solar power. What’s more, they remain too expensive. A lithium battery currently costs around 400 euros/kWh. Although this amount could fall by half over the next five years, lithium batteries would still remain more expensive than their lead counterparts. A way of overcoming this problem would be to combine large lead batteries with small lithium-ion batteries. To protect lead batteries from peaks in demand, which could result in damaging over-discharge, lithium-ion batteries should be employed during peaks in demand, while lead batteries should be used to cover base load.
Lead-acid batteries with dilute sulfuric acid acting as a liquid electrolyte
36
As the cost of storage falls with increasing lifespans, a battery’s cycle life is of great significance. Taking into consideration the levels of insolation normally seen in Germany, batteries need to be charged and discharged around 3,000 to 4,000 times in the space of 20 years. Lithium-ion batteries have already achieved a cycle life of this extent. Lead batteries, on the other hand, are only capable of performing around 1,000 cycles, outweighing the advantage of their lower investment costs – unless, of course, they are combined with lithium batteries (see above). Overall, the drop in prices brought about by the technical development of storage media and the economies of scale resulting from mass production, as well as the coordinated interplay between the various forms of storage, shall contribute to ensuring that the share of photovoltaics in the power supply continues to grow.
Plant Monitoring and Identifying Faults
Plant Monitoring and Identifying Faults Every kilowatt hour counts, because only kilowatt hours that are fed into the grid or privately consumed are remunerated. It is therefore necessary to thoroughly monitor operational data. A plant’s operator can only take prompt measures to eliminate operational faults and failures where these are signaled immediately. Merely reading the feed-in meter each month is not sufficient to recognize faults promptly and to avoid the loss of yields. Constant measurements are therefore necessary to ensure optimal operation.
Plant monitoring using thermal imaging P hoto : Tom Baerwald / L ebherz
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Plant Monitoring and Identifying Faults P hoto : Tom Baerwald / L ebherz
P hoto : Tom Baerwald / L ebherz
Measuring insolation using a pyranometer
Thermal imaging flight
Constant measurements are essential Many inverters record the most important operational data, evaluate the data automatically and, in the event of a fault, send the operator notifications via email, text message or internet. This is sufficient for basic plant monitoring. However, it only allows obvious faults, such as fault currents or total failure, to be recorded. In order to determine whether a PV plant is producing optimal yields, the plant data needs to be measured continually, and preferably compared with the actual radiation values present. This is due to the fact that currents and voltages, and consequently feed-in capacities, constantly change depending on meteorological conditions. The operator can only determine whether or not the PV plant’s operational data indicate optimal functioning by directly comparing them with insolation data. Measuring insolation and output Solar radiation is measured using either pyranometers or PV sensors (reference cells). A third – more indirect – possibility is to compare a plant’s data with meteorological information and yields from PV plants in the vicinity. Pyranometers measure insolation with great accuracy. They essentially consist of one or two hemispherical glass domes, a black platelet that acts as an absorbing surface, the thermal elements positioned below this and a metal casing. Solar radiation heats the absorbing surface, the warming of which is directly dependent on the insolation. Insolation can thus be
38
ascertained from the temperature difference between the absorbing surface and the white metal casing. Pyranometers are installed horizontally when meteorological data is needed and in the module plane when PV output requires monitoring.The advantage of high measuring accuracy is, nevertheless, opposed by a serious disadvantage: Due to their thermal functionality, pyranometers are relatively sluggish, which means that they are incapable of accurately detecting rapid insolation fluctuations caused, for example, by scattered clouds. PV sensors, which are also installed in the module plane so that they are exposed to the same insolation conditions as the modules, provide a cost-effective alternative to the accurate, but slow and expensive, pyranometers. A PV sensor consists of a solar cell which supplies power in proportion to insolation. This power is, however, also dependent on the operating temperature of the solar cell, which means that a temperature sensor is necessary in order to offset thermal effects and determine the exact insolation. However, owing to its limited spectral response, the solar cell cannot detect certain portions of the insolation, and reflection losses may also occur. PV sensors are therefore much less accurate in their measurements of insolation than pyranometers. Despite this, they are often used to monitor PV plants. This is because a PV sensor can be selected to correspond to a plant’s modules. For example, a PV plant consisting of CI/GS/Se thinfilm modules is monitored by a PV sensor with a CI/GS/Se solar cell. This simplifies the comparison of instantaneous values, which means that operational faults and defects can be recognized quickly.
Like silicon-based PV sensors, pyranometers measure absolute insolation in watts per square meter (W/m2). Thanks to their technological differences, however, they are capable of recording slightly different solar spectrums (while silicon cells’ restricted spectral response means they are only able to perceive the “silicon spectrum”, pyranometers are able to register the entire solar spectrum). Consequently, when measuring global irradiation, pyranometers invariably record higher levels of insolation than silicon sensors, and, conversely, lower performance ratio (PR) values, as a result of global insolation being used to calculate the denominator of the PR formula. When exposed to the same level of insolation, modules produce a greater output on a cooler day than on a warm day, meaning that it may be necessary to measure the operating temperature of the modules in order to determine the exact output. Comparisons with regional meteorological data mean that pyranometers and PV sensors are no longer required. Yield simulations are calculated using data supplied by neighboring meteorological offices and compared with the actual yield. Operators can also check their own performance data by examining the yield of nearby PV plants. Both methods have the disadvantage that faults often go unrecognized for hours or even days. Furthermore, the validity of this comparison is limited by regional differences such as cloud cover or vegetation. A rule of thumb is that a PV plant with a generator output of 100 kWp or more should be fitted with an on-site insolation measuring system. Nevertheless, it is also worth measuring on-site insolation in plants with lower capacities.
Plant Monitoring and Identifying Faults P hoto : Tom Baerwald / L ebherz
P hoto : Tom Baerwald / L ebherz
Measuring the output of an inverter
Plant monitoring
Insolation data obtained from satellite pictures may also be consulted in order to determine whether the PV plant is running efficiently. The yields are recorded hourly and sent to a server via the internet once a day. There, the data are compared to the yields expected. This method achieves an average accuracy – although not very quickly – comparable to plant monitoring with PV sensors. If a fault is identified, it often cannot be rectified immediately because the target value and actual value of the yield are only compared once a day. Another method of monitoring a plant is the continuous comparison of output supplied by the individual module strings (string monitoring). If all the strings have been installed with the same orientation, then their output should always be the same. If it is possible that partial shading could occur, this is known in advance. Therefore, if a string unexpectedly falls behind the others this means that there must be a fault. String monitoring is a quick, simple and effective method of identifying yield losses. If operational data are saved on the internet, a service provider (or “technical plant manager” in the case of large-scale installations) can assume the task of monitoring the plant and then inform the operators of any faults which occur, or even take independent measures to rectify them.
Causes of faults resulting in yield reduction Yield losses can generally be attributed to three causes of faults. Component faults, installation faults and faults caused by external influences. Component faults are more frequently found in inverters than modules. These can be due to production faults, aging or thermal overload of the inverters. Such faults often lead to the complete failure of either the PV plant or the part of the generator connected to the defective inverters. An increasing number of inverter manufacturers are, therefore, now providing long-term guarantees and service contracts. PV modules are not as badly affected by thermal overload as inverters, but rather by external influences, although this happens over relatively long periods of time. As shown by several experiments running for extended periods of time during the 1980s, crystalline solar modules are able to supply power for 20 years without showing significant signs of aging. Provided that the manufacturer has put a sound quality management system in place, production faults are often identified in the factory, meaning that broken cells or incomplete lamination only rarely appear in a PV plant as component faults.
glazing may crack due to the effects of temperature and wind. Individual modules or even whole strings will continue to fail as a result of electrical connections not being installed carefully enough. Insulation can also be adversely affected by installation faults. For this reason, it is wise to use an automatic insulation monitor, which is integrated into some inverters. External influences primarily affect PV modules. Over the decades, UV radiation from the sun will lead to light aging. The darkening of the plastic film (browning) can lead to a reduction in module output (degradation). Weather-induced aging is only observed relatively rarely in the plastics, in which the solar cells are embedded. Cell damage occurs more often, which is caused by shading and subsequent excessive heating (hot spot). Bypass or string diodes may be damaged by thermal overload or overvoltages. Inverters are not normally directly exposed to meteorological conditions although they are adversely affected by circuit feedback, for example.
Installation faults rarely result in complete plant failure but only in partial yield reduction. Sometimes, installation faults only start to take effect after a certain time, which means that they are recognized far too late. If, for example, modules are installed so close to one another that there is no longer an expansion gap, the
39
Stand-Alone Power Systems and Grid-Parallel Operation
Stand-Alone Power Systems and Grid-Parallel Operation Thanks to their simple, modular structure, PV installations are suitable for virtually all service environments the world over. In countries lacking local power grids, they form autonomous, stand-alone power systems that can be expanded as needed, and are thus a driving force in “rural electrification”. PV plants installed in areas where power grids exist but are unreliable are something of a specialty. They operate in parallel to the grid and then bridge periods when the power fails.
As seen here on Haiti, stand-alone solutions comprising a small solar module, a charge controller and a battery have been designed for consumers who are not connected to a central power grid. P hoto : S olarworld AG
40
Stand-Alone Power Systems and Grid-Parallel Operation
Hybrid system 8.
9.
6.
1.
7. Future extensions possible
2. 3.
10.
150 kWp 4.
Solar power for remote locations Stand-alone systems are the original preserve of photovoltaics. The simplest installations consist of a PV module and a device that consumes DC, such as a water pump. Photovoltaic systems are straightforward to install and benefit from low operating costs. In remote regions, located at great distances from the power grid, they are therefore often unrivalled on price – particularly when the only alternatives are diesel generators that consume expensive fuel. Continually falling module prices together with rising prices for fossil fuels are also clearing a path for such systems in other markets. If small, stand-alone installations require a 24-hour power supply, the PV plant is combined with a battery system, as is the case in weather stations, navigational aids and transmitter masts. Here, electronic charge controllers are employed to ensure that the power supplied by (mostly individual) PV modules is stored in the batteries as efficiently as possible. DC power consuming equipment (such as lamps and refrigerators) is connected to the charge controller and is thus supplied either by the solar power generated at a given moment or by power stored in the batteries. This principle is that of the “solar home system”.
5.
Backup systems (e.g. diesel or vegetable oil generators) improve supply security. This has led to the creation of hybrid systems that can be used, for example, in hunting cabins and refuges, and even on large yachts. With the development of PV technology, stand-alone systems have grown into autonomous grids and have become more diverse. If intended to supply power to schools, hospitals, entire villages or even small islands, the PV systems are usually supplemented by small wind turbine generator systems as well as batteries and diesel or vegetable oil generators. Biogas plants can also be integrated into these autonomous grids. As such grids increase in size, cheap devices that consume AC (refrigerators, TVs and other household appliances) are used in addition to those that consume DC, meaning that inverters become necessary alongside charge controllers. It is not only possible to structure hybrid systems as either pure DC systems or mixed AC/DC systems, pure AC configurations are also available that are flexible and can be expanded. Special inverters are needed for such systems. A standalone inverter primarily has two tasks: It charges the batteries to store any solar power not used immediately and creates a stable AC network.
Using solar energy to support the power grid: Since the grid power supply is unreliable, a PV installation in Chennai (India) is used to produce power during the day. At night, a diesel generator ensures electricity is still available. Surplus solar power is stored in a battery.
Additional PV systems and the fuel driven generators feed into the AC network, coupled with a wind turbine generator system (preferably also with a special inverter) or biogas plant when large amounts of power are needed. The better the levels of insolation and wind complement one another over the course of a day, week or year, the less frequently the back-up generator is used. Power storage systems are needed to stabilize the grid. In addition to ensuring that electricity is available around the clock as far as possible, they also decrease short-term power fluctuations which arise as a result of clouds passing overhead, for example, and cause PV output to fall by up to 80%. If a hybrid system supplies an entire village, a micro grid is created. Several of these stand-alone systems can then be combined to form a mini grid. Standalone systems gradually grow together into ever larger grid units, thus representing a major contribution to rural electrification in developing countries.
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Stand-Alone Power Systems and Grid-Parallel Operation
Stand-alone PV systems System
Power range
DC loads
Simple DC motors, fountain pumps, fans
Pumps cathodic protection
Pumps with power conditioning, cathodic protection
AC loads
Larger AC pumps, or other AC drives
DC loads
Miniature appliances, pocket calculators, watches Mobile applications, telecom, medical refrigeration, bus shelter lights, small SHSs
DC loads
Autonomous DC loads, emergency telephones, clocks (with load management)
DC loads
DC loads
Remote homes, schools, hospitals - with additional power source (diesel / wind) in larger installations
PV module(s)
Inverter
Lead-acid or NiCd battery, capacitor
Additional power source (diesel, wind)
Bridging bottlenecks Between PV plants that supply standalone systems and those that feed into the public grid come installations that generate power in parallel to the grid (grid-compatible parallel operation). Grid-parallel operation is necessary anywhere where a public grid exists but the power supply is unreliable. Moreover, such systems are also practical in situations where a large power consumer (such as a factory) is connected to a weak grid spur and the power demand regularly exceeds the capacity of the grid connection. In both cases, photovoltaics assists in stabilizing the power grid and bridging bottlenecks in supply. To date, this task has been performed by diesel generators. But in view of rising oil prices and PV generation costs that continue to fall, it makes far more practical sense to install PV systems. This is especially true in regions with high levels of insolation. In many cases, photovoltaics is already capable of generating power for profit in these regions, as illustrated by this simple case study:
10,000 W
AC loads
42
Application
DC-DC converter
Charge controller, battery monitoring
A factory in India that operates around the clock, but is plagued by frequent power failures, relies on a diesel generator to supply power during the power cuts. This generator can produce power at all times of the day for 20 euro cents/ kWh. Thanks to the high levels of insolation there, a PV installation is able to generate electricity throughout the day for 10 euro cents/kWh. Both systems operate in parallel to the grid. During the day, the PV installation has priority, while at night the diesel generator is responsible for securing the power supply. Surplus solar power produced during the day can also be stored using a battery system, increasing the availability of that power even further. This increases the availability of the battery and makes it possible to use solar power at nighttime. A progression of this system is based on a situation where the PV installation produces distinctly more power than the factory requires and consists of two PV generators. The larger of these supplies the factory with electricity throughout the day and feeds any surplus power into the battery system. The smaller PV generator is tasked solely with ensuring that the battery is fully charged, so that
enough power is available during the night. Wind energy installations can also be connected to this system and supply power to the factory. The diesel generator is currently still needed as a backup power source, but provided the latest radical developments in battery technology continue, it will foreseeably become redundant in the medium term.
Protection against Lightning and Overvoltage
Protection against Lightning and Overvoltage Highly excessive voltages and currents can threaten the operation of a PV plant. Such surges are mainly caused by lightning strikes, but also by faults in the grid. Ensuring a path to earth for any lightning or currents caused by overvoltage is an extremely important factor in PV plant protection.
Electric and magnetic fields that could damage PV plants are created by the high voltages and currents caused by lightning strikes. P hoto : Tom Baerwald
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Protection against Lightning and Overvoltage
Surge protection measure
Surge protection measure: DC cables of the same string bundled together to avoid loops in which voltage surges can be induced.
Assessing the risks is essential In principal, a PV plant does not generally increase the risk of a building being struck by lightning and a separate lightning protection system does not necessarily need to be constructed simply because a PV plant has been installed. Nevertheless, the VdS (German Testing Institute for Fire Protection and Security) recommends installing a lightning and overvoltage protection system for all plants with a capacity of 10 kW or more. Many insurance companies follow this recommendation and only offer insurance cover if sufficient protection of this kind is in place. In individual cases, the risks should therefore be assessed in order to enable a decision in favor of or against the construction of a lightning and overvoltage protection system, and to allow plant operators to present arguments to insurance companies. If the building on which the PV plant is constructed is already equipped with a lightning protection system (e. g. a public building or venues open to the public), the PV plant must be integrated into the protection concept. The standard DIN EN 62305 (VDE 0185-
P hoto : O B O B E T T E R M A N N G mb H 6 Co. KG
305):2006-10 provides a comprehensive approach to internal and external lightning protection for buildings and systems. In particular, the supplementary sheets to this European standard offer practical support when deciding whether or not to install a lightning protection system, as well as details on how to install such systems properly. Photovoltaic installations are primarily discussed in Supplement 5 “Lightning and surge protection for PV power supply systems”.
Indirect effects
External lightning protection includes all measures for arresting lightning and conducting it to ground, and consists of a lightning current arrester, a down lead capable of carrying lightning and a grounding system which distributes the lightning current in the earth.
An integrated lightning protection system comprising measures and equipment within the PV plant and in the building is, therefore, required. Its fundamental purpose is to prevent inductive coupling and provide a path to earth for currents caused by overvoltage.
Priority must be given to preventing the lightning from directly hitting the modules. This is first and foremost necessary when the PV generator has been installed in an exposed area (elevated on a flat roof, for example). Rods or wires are used as lightning current arresters, and the core shadow of these should not be cast on the modules as far as this is possible. Somewhat smaller air terminal rods are, therefore, placed in front of the solar modules and somewhat larger ones are placed behind the modules. The exact number and spacing of the air terminal rods is given by the class of protection desired and is calculated using methods such as the “rolling sphere method”.
In order to keep coupling in the module cables to a minimum, the area of the open conductor loops in the generator circuit must be as small as possible. The outgoing and return lines of the strings are, therefore, laid as close as possible to each other. The use of shielded single lines also reduces the risk of lightning effects.
Lightning protection system on a roof-mounted PV plant
44
The probability of indirect lightning effects occurring is significantly higher than that of a direct lightning strike. This is because every lightning strike within a one-kilometer radius can generate current flow in the modules, module cables and in the main DC cable by means of induction. Conductive and capacitive coupling are also possible and can equally cause overvoltage.
Surge protection devices (SPD) not only prevent inductive coupling but also the occurrence of grid-side overvoltage, and are normally built into the generator junction box. Because varistors used as voltage dependent resistors can age due to leakage currents, the combination of two varistors and a spark discharger in Y connection is considered the safest longterm protection against overvoltage.
Protection against Lightning and Overvoltage P hoto : Tom Baerwald
Both direct and nearby lightning strikes pose a risk to PV plants.
Installation of a lightning protection system
String fuses in the GJB can also generally prevent the cables from becoming overloaded in the event of faults. These are intended to reduce the risk of electric arcs.
P hotos : W eidm ü ller G mb H & Co. KG
P hoto : M ichael Streib - Sachverstä ndiger
Overvoltage protection modules (red and blue) in generator junction boxes
Since DC and DC voltage are generated in a PV plant, there is a danger that nonself-extinguishing arcs could be created, which could cause fire. This danger is not present in an AC circuit because the regular zero crossing of the AC’s sine curve immediately extinguishes any electric arc created. The electrical connections in the DC circuit of a PV plant must therefore be extremely secure, because a loose connection can lead to sparking and, consequently, trigger an electric arc. As a result, when laying the DC cables of a PV plant it is standard to protect them from short circuit and ground leakages. This is achieved by tidy cable routing (e.g. not running unprotected over sharp edges) and the use of separate positive and negative cables, as well as double cable insulation. The DC cables used should be tested to “PV1-F” standards and marked accordingly.
P hoto : D ehn + S ö hne G mb H + Co. KG
Reverse current and electric arcs Increased currents can also occur if there is a voltage drop in a string, caused for example by shading or a short circuit. If this happens, the parallel-connected strings will function like an external power source which drives a fault current in the direction of consumption (reverse current) through the modules of the defective string. If the reverse current resistance of the modules is exceeded they will start to heat up, so string diodes are used to prevent such reverse currents. Many PV plants today are, however, built without string diodes, as most modules now have higher reverse current resistance and will easily withstand reverse current of 10 to 20 amps.
The exposed location and expansive surface area of photovoltaic plants put them at particular risk of being affected by lightning.
45
Cables and Connectors
Cables and Connectors The electrical connections in a system may be inconspicuous, but their effects should not be underestimated. As a relatively large number of electrical connections are required in order to connect the modules of a PV plant to the inverter, the losses at contact points can add up. Long-lasting, secure cable connections with low contact resistances are necessary to avoid defects, losses and accidents.
Assembly of a junction box to a flexible solar module P hoto : Tom Baerwald /G lobalsolar
46
Cables and Connectors
P hoto : P H O E N I X CO N TAC T D eutschland G mb H
Inverter cable connection
Safe and weatherproof connections A PV plant’s electrics consist of the DC cables between modules, generator junction box and inverter, and the AC cable running from inverter to grid. The cables and wires must be laid in such a way to ensure that they are ground-fault and short-circuit proof. To achieve this, the DC installation is made up of two singlecore, double-insulated cables that should be tested in accordance with the PV1-F standard. As the cables are almost exclusively laid outside, the insulation must be weatherproof. A three-core AC cable is used for connection to the grid if a singlephase inverter is used, and a five-core cable is used for three-phase feed-in.
Solar cables, which are UV and weather resistant and can be used within a large temperature range, are laid outside. Single-core cables with a maximum permissible DC voltage of 1.8 kV and a temperature range from –40 °C to +90 °C are the norm here. A metal mesh encasing the cables improves shielding and overvoltage protection, and their insulation must not only be able to withstand thermal but also mechanical loads. As a consequence, plastics which have been cross-linked using an electron beam are increasingly used today. The cross-section of the cables should be proportioned such that losses incurred in nominal operation do not exceed 1%. String cables usually have a cross-section of 4 to 6 mm2.
Owing to the sharp increase in copper prices, aluminum has recently gained significance as an electrical conductor. It is possible to save around 50% by using aluminum cables, particularly for underground cables at low and medium voltage levels. However, their poor conductivity means that they are thicker than copper cables. Careful attention must also be paid to the default breakaway torque of their screw connections, as, in comparison to copper, aluminum tends to creep under roofs which are (too) heavy. If the screw connections are too tight, the cable loosens over time, possibly resulting in an electric arc, not to mention the associated risk of fire and all the consequential damage.
P hoto : Tom Baerwald / Parabel AG
Cables connect individual modules to the PV generator. The module cables are connected into a string which leads into the generator junction box and a main DC cable connects the GJB to the inverter. In order to eliminate the risk of ground faults and short circuits, the positive and negative cables, each with double insulation, need to be laid separately. The sharp edges must be fitted with edge protectors. The minimum bend radius must be taken into account when laying the cables and wires, and it is important that they are fixed in a durable and sufficient manner.
To avoid them acting like a burning fuse, which could cause fire to spread to neighboring houses, solar cables must not pass over or through firewalls unprotected. If laying the cables in this way cannot be avoided, they must be protected with a fire-resistant sheath. Further options include laying them in fire-resistant ducts or using a fireproof bulkhead.
Cabling work at a ground-mounted PV plant
47
Cables and Connectors
P hoto : M ulti - Contact AG
Example of strings connected in parallel
Losses add up Connection technology has needed to develop rapidly over the last few years, as inadequate contacting can cause electric arcs. Secure connections are required that will conduct current fault-free for as long as 20 years. The contacts must also show permanently low contact resistance. Since many plug connectors are required in order to cable a PV plant, every single connection should cause as little loss as possible, so that losses do not accumulate. Given the precious nature of the solar power acquired from the PV plant, as little energy as possible should be lost. Screw terminals and spring clamp connectors (e.g. in the module junction boxes and for connection to the inverter) are gradually being replaced by special, shock-proof plug connectors, which simplify connection between modules and with the string cables. Crimp connection (crimping) has proven itself to be a safe alternative for attaching connectors and bushes to the cables. It is used both in the work carried out by fitters on the roof and in the production of preassembled cables in the factory. Here, litz wire is pressure bonded with a contact using a crimping tool, which causes both to undergo plastic deformation creating a durable connection. An alternative plug connector design has been developed to allow the connection to be fixed in place without the need for special tools: In this instance, the stripped conductor is fed through the cable gland in the spring-loaded connector. Subsequently, the spring leg is pushed down by
48
thumb until it locks into place. The locked cable gland thus secures the connection permanently. Plug connectors and sockets with welded cables are also available on the market. Such connections cannot, however, be used during installation work on the roof, but only during production in the factory. Another development are preassembled circular connection systems for the AC range. These are intended to reduce the high levels of installation work required when several inverters are used within one plant. Standards for plug connectors Since PV modules generally come equipped with pre-assembled plug connectors, several modules can easily be connected to form a string. Connecting these strings to the inverter or generator junction box, on the other hand, is not always straightforward. A variety of different cable connectors are available on the market, and as yet no standards have been established for these interconnection systems. Plug connectors from different manufacturers are usually either completely incompatible or they fail to provide a connection that will remain permanently snug. If the connector fits too tightly, this can cause the insulating plastic parts to break. A loose fit, on the other hand, poses the risk of creating high contact resistance. This leads to yield losses and the areas around the connection heating up, even causing an electric arc and the connector to melt.
When connecting a plug with a socket from a different manufacturer, a crossover connection is created, which can generally only be proved to be reliable if complex, expensive tests are performed. In addition to measuring the contact resistance and determining the connection strength, accelerating aging tests and weather exposure tests must also be carried out. Such tests will make it clear whether or not the different materials are compatible. This concerns both the metals used to manufacture the contacts and the plastic materials employed. There are currently no crossover connections which have been tested in accordance with DIN EN 50521 VDE 01263:2009-10: “Connectors for photovoltaic systems; safety requirements and tests” and approved by both manufacturers (socket manufacturer A combined with plug manufacturer B or socket manufacturer B combined with plug manufacturer A). A standard for photovoltaic plug connectors, which should be as international and uniform as possible and is similar to that for domestic Schuko plugs, is desirable and necessary to ensure reliable connections between products from different manufacturers. If such a standard were to be introduced, manufacturers would be in a position to offer reciprocal warranties for specific crossover connections.
Market Situation and Forecasts
Market Situation and Forecasts Since 2006, solar installations have grown year-on-year. This trend will continue to happen in 2013 and every year after that until at least 2017. Encouraging as that may seem, however, the picture is much more sobering when one looks at industry revenues. Whereas PV installation will grow at a double-digit rate in 2013, revenues will fall to 75 billion US dollars.
Jännersdorf solar park in Brandenburg (Prignitz, Germany) with an output of 40.5 MW. 168,000 polycrystalline modules generate around 38 million kilowatt hours of power per year on a site covering around 90 ha. P hoto : Tom Baerwald / Parabel AG
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Market Situation and Forecasts
PV installation per region (GW)
Americas
Asia
EMEA*
60,000 50,000 40,000 30,000 30,000 10,000
2010
2011
2012
2013
2014
2015
2016 * Europe, Middle East, Africa
Industry revenues
Globalization of the industry
Midsized markets
Industry revenues – measured as system prices multiplied by total gigawatts installed – peaked at 94 billion US dollars in 2011, but fell sharply to 77 billion US dollars in 2012. Revenue is projected to decline once again in 2013 to 75 billion US dollars, on the back of lower volume growth and continued system price declines, given that PV component prices continue downward.
But an equally imposing problem for companies will be the rapid globalization of the industry. Back in 2010, Europe accounted for more than 80% of solar demand, which then contracted to 53% in 2012. This will shrink further in 2013 to 39%, and Asia will then replace Europe as the world’s largest solar market. Historically, solar companies could focus on Germany and a few other European countries to support their business, but these same companies need to now quickly accelerate their entrance into emerging markets around the world.
Perhaps more important than next year’s changing rankings of the biggest markets is the geographic fragmentation that we predict will accelerate in 2013. While nearly three quarters of total solar demand in 2012 came from the top 5 end markets, the total proportion will drop to 65% in 2013 as the market fragments. This is because of the increasing importance of “midsized” markets installing a few hundred megawatts per year.
The conflicting trend of growing volumes but falling revenues will, of course, challenge solar companies to continue to reduce their cost structures.
50
Germany is predicted to be displaced by China in 2013 as the world’s largest solar market – a position that Germany has held for the last seven years, with the sole exception occurring in 2008. The United States is also forecast in 2013 to add more solar installations than Germany, which will drop down to third place, followed by Japan and Italy in fourth and fifth, respectively. This geographic shift presents a challenge in itself given that China is almost inaccessible to Western suppliers, with Japan proving equally challenging for non-domestic vendors, and the USA impacted by the recent anti-dumping trade case.
The good news is that more stability will result for this boom-bust industry, because a single government’s incentive policy will have less impact on the overall global market. But along with this stability will come intense challenges for solar companies as they are forced to globalize business by setting up new sales and service networks, complying with local requirements and grid codes, and navigating past the “quick-hit” markets that are here one year and gone the next. Despite the likelihood that 2013 will be another challenging year for solar companies, the longer-term picture looks somewhat more positive with installations – and more importantly, with industry revenues that are predicted to grow at a double-digit rate between 2014 and 2016. As a result, industry revenues will soar past the 2011 peak to 115 billion US dollars by 2016.
S ource : I H S P V M arket T racker Q 4 2 0 1 2
Global demand forecast
Market Situation and Forecasts S ource : I H S P V M arket T racker Q 4 2 0 1 2
Top 5 solar markets in 2012 and 2013 2012 MW Installed
2013 MW Installed
1
Germany 8,000
1
China 6,300
2
china 5,100
2
USA 5,100
3
USA 3,600
3
Germany 5,000
4
Italy 3,500
4
Japan 3,500
5
Japan 2,200
5
Italy 2,900
The FiT for small PV systems has fallen below the retail price of electricity in the world’s largest PV market, Germany. New system owners in Germany will sell their electricity for less than they are buying it back for. A residential system owner now effectively has a financial incentive to use as much of their electricity as pos-
This article is an excerpt of IHS Solar Whitepaper on 2013 Market Predictions, December 2012. The document can be downloaded at www.imsresearch.com/media_contact.php?sector=6.
0.8
0.7
Nov 2012
Oct 2012
Sep 2012
Dec 2012 (Exp)
0.9
Aug 2012
Jul 2012
Jun 2012
US$
May 2012
Chinese c-Si module price by region Jan / Feb 2013 (Exp)
Energy storage systems (ESS) for PV
A strong influx of new products from inverter manufacturers is expected to tackle this market with an array of solutions. The solutions range from inverters with the capability to have batteries attached to full solutions with batteries integrated and intelligent energy management systems that switch between energy sources and charge/discharge batteries in order to achieve the most economical and efficient supply of electricity. IHS will provide a detailed forecast by May 2013, expecting a strong increase of PV energy storage systems in 2013 and the years to come.
US$ 0.9
0.8
0.7
EU NAFTA*
0.6
ROW Japan China
0.6 *North American Free Trade Agreement
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S ource : I H S S olar R esearch , D ecember 2 0 1 2
Despite such gloomy developments during the course of 2012, more stable cell prices are predicted ahead. This means that c-Si module price reductions will also slow, even though the end market might still be expecting bigger price cuts. All told, IHS predicts c-Si module prices will stabilize by the middle of next year. The anticipated stabilization of prices – from polysilicon to c-Si modules – will be due to a moderate cut in production among Tier-1 polysilicon suppliers.
Apr 2012
Looking ahead: more stable prices predicted
Mar 2012
A drastic decline in prices along the silicon supply chain has taken place since March 2011. As of November 2012, Chinese module prices have declined by more than 25% on average from their 2011 levels. The drop can be seen in the figure below, which shows Chinese c-Si module prices, differentiated according to the region in which the modules were sold. The time frame spans the period from February to December 2012; figures from November to December are forecasts and estimates from IHS Solar research.
sible. Still, the investment into a storage system is not very attractive financially. That’s why the German government has announced a subsidy program for energy storage. The subsidy program got everyone’s attention; however, its scope is much more limited than that of the original EEG. It consists in subsidized (reduced interest) loans and a 30% cash grant for the purchase of the storage system. The program is limited to PV systems up to 30 kWp. The applying PV systems are restricted in feeding to the grid at a maximum 60% of the nominal output power of the PV systems. These measures shall help to integrate more PV systems into the existing grid by capping the power peaks at local level. The date of the introduction is yet to decide (as of March 2013), cf. www.kfw.de.
Feb 2012
PV module prices to stabilize in 2013 as oversupply eases
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The Companies
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Overview
Overview Companies and brands presented at a glance (in order of appearance)
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Overview
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Business Areas
Business Areas
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Companies (in alphabetical order)
Company
58 ABB 60 Advanced Energy 61 AEG Power Solutions 62 Bonfiglioli Riduttori S.p.A. 63 Bosch Power Tec GmbH 64 Danfoss Solar Inverters 65 Diehl Controls – PLATINUM® GmbH 66 Fronius Deutschland GmbH 67 GoodWe 68 W. L. Gore & Associates GmbH 69 Ingeteam Power Technology S.A. 70 KOSTAL Industrie Elektrik GmbH 71 KOSTAL Solar Electric GmbH 72 LTi REEnergy 73 Mastervolt International BV 74 meteocontrol 75 Multi-Contact AG 76 Nidec ASI S.p.A. 77 OBO BETTERMANN GmbH & Co. KG 78 Phoenix Contact GmbH & Co. KG 65 PLATINUM® GmbH – Diehl Controls 79 Power-One 80 REFUsol GmbH 81 Saft 82 Schneider Electric 83 skytron® energy GmbH 84 SMA Solar Technology AG 85 Solare Datensysteme GmbH 86 SolarMax 90 Solarpraxis AG 87 Steca Elektronik GmbH 91 Sunbeam GmbH
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Business area: inverters
4.99 MWp PV power plant in Malmesbury, UK, powered by ABB PVS800 central inverters
ABB Oy, Power Conversion Address: H iomotie 13 00380 Helsinki · Finland Phone: + 358 (0)10 22 11 Email:
[email protected] Web: w ww.abb.com/solar Year founded: formed in 1988, merger of Swiss and Swedish engineering companies with predecessors founded in 1883 and 1891 Employees: 145,000 (ABB Group)
ABB
Inverters for the Entire Spectrum without Losing a Watt ABB offers a comprehensive solar inverter portfolio. With decades of experience in power technology products, ABB has the know-how, life-cycle services and personnel to support PV installations worldwide for years to come.
ABB has been working for decades to offer products and solutions to reduce the environmental impact of energy systems. ABB manufactures and supplies a broad range of leading-edge solutions for the photovoltaics (PV) market, suitable for the smallest building applications, right up to large megawatt-sized power plants. The comprehensive portfolio includes single components such as solar inverters, low voltage products, transformers, and switchgears up to complete turnkey power plants. Whether the PV systems are large power plants or industrial, commercial or residential building applications, ABB’s high-quality products, systems and services provide optimum return on investment. Powerful solar inverters with global presence The ABB solar inverter utilizes over 40 years of advances in inverter and power converter technology that has contributed to ABB becoming the world leader in frequency converters and one of the biggest suppliers of wind turbine converters. ABB offers a complete portfolio of solar inverters from small transformerless single-phase string inverters up to transformerless central inverters with power ranges amounting to hundreds of
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50.6 MWp PV power plant in Pobeda, Bulgaria, powered by ABB PVS800 central inverters
kilowatts. Furthermore, ABB solar inverters are supported through a worldwide sales and service network that provides a complete range of life-cycle services. ABB central inverters for photovoltaic power plants ABB central inverters are aimed at PV power plants and large industrial and commercial buildings. Based on ABB’s marketleading technology platform in frequency converters, the central inverters comprise proven components with a long track record of performance excellence in demanding applications and harsh environments. Equipped with extensive electrical and mechanical protection, the inverters are engineered to provide a long and reliable service life of at least 20 years. A wide range of options like remote monitoring with string current measurements, fieldbus connections and integrated DC cabinets are available. Thanks to the inverters’ certificates and advanced and flexible grid support functions, ABB central inverters can meet all applicable network connection requirements. During the last ten years, ABB has delivered over 100 GW of power converters on the same platform that is used for central inverters. During their first few years of use alone, ABB central inverters gained an
established position in the solar business, with nearly 1 GW of installed capacity. The inverters are available from 100 to 1,000 kW. ABB string inverters for residential buildings ABB string inverters are designed for PV systems installed on residential, commercial or industrial buildings. The inverter’s all-in-one design includes the necessary protection functions built into the inverter, which reduce the need for costly and space-consuming external protection devices and larger enclosures. The result is a more compact, reliable, safer and costeffective solution, especially in installations using multiple inverters. The heart of the inverter is the intuitive control unit equipped with a graphical display. It offers a comprehensive range of key functionalities that are easy to use with built-in assistants and a help menu. The control unit has three different mounting options. It can be integrated in the inverter housing or mounted separately on a wall to monitor inverter performance from outside the installation room. It can also be wirelessly connected to enable the inverter to be installed in a remote part of the site and monitored wirelessly from inside the main building. The inverters are available from 3.3 to 8 kW.
Turnkey solution for large-scale solar power generation The ABB megawatt station design capitalizes on ABB’s long experience in the development and manufacture of secondary substations for electrical authorities and major end users worldwide in conventional power transmission installations. A station houses two ABB central inverters, an optimized transformer, medium-voltage switchgear and a monitoring system, which connect a photovoltaic power plant to a medium-voltage electricity grid easily and rapidly. All components within the megawatt station are part of ABB’s product portfolio. The steel-framed insulated container comes complete with a concrete foundation, also designed and produced by ABB. The station’s thermal insulation enables operation in harsh temperature and humidity environments and is designed for at least 20 years of operation. The megawatt station is available in two sizes: 1 MW and 1.25 MW. ABB is a leader in power and automation technologies that enable utility and industry customers to improve their performance while lowering environmental impact. The ABB Group of companies operates in around 100 countries and employs about 145,000 people.
ABB PVS800 central inverter, 1,000 kW
ABB PVS800-MWS megawatt station
ABB PVS300 string inverter, with control unit
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Business areas: inverters monitoring/supervision LOP connection technology planning and grid integration software/IT
Advanced Energy Founded in 1981, Advanced Energy (Nasdaq: AEIS) is a global leader in reliable power conversion solutions. AE’s solar energy business delivers highly reliable inverters, complementary BoS products, and O&M services that allow our customers to secure more solar projects and grow their business.
AE’s PowerStations generate electricity dependably, optimize Levelized Cost of Energy (LCOE) and help stabilize grid operation.
150 MW solar project utilizing AE’s 2 MW integrated skid solutions
Solar plant in Vermont, USA
AE Solar Energy Address: 2 0720 Brinson Blvd. Bend, OR. 97701 · USA Phone: + 1 877 312-3832 Fax: + 1 541 312-3840 Email:
[email protected] Web: w ww.advanced-energy.com/solarenergy Year founded: 1981 Employees: 1,500
Customer experience AE Solar Energy enables utility-scale and commercial solar project stakeholders to offer system owners a lower Levelized Cost of Energy (LCOE) and the confidence that their PV system will deliver on longterm production goals. With more than 30 years of leadership in delivering innovative energy solutions, combined with a legendary reputation for customer service and a strong balance sheet, AE is a trusted partner to solar project developers, financiers, and beneficiaries around the globe. Innovation AE is never satisfied: From our roots in reliability and LCOE to continually improving our quality, systems and people, we ensure that energy is delivered, period. We pioneer improvements in distributed generation, grid interactivity performance, utility interactive functionality, and energy management solutions.
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Energy delivered™ AE delivers highly reliable and efficient inverters designed with an architecture optimized to deliver the LCOE. Our simplified BoS solutions reduce system design support, project management time and increase savings on installation. Simply put, AE delivers life-cycle performance. Solar site solutions AE delivers whole-site operations and maintenance service plans that increase the reliability of customers’ PV systems. AE global services is dedicated to responding quickly to issues, whether that means rolling a truck, providing phone support or anything in between. We provide application engineering support and warranties for up to 20 years, partnering with customers for the entire project life-cycle.
Business areas: inverters storage technologies planning and grid integration monitoring/supervision power plant control
AEG Power Solutions AEG Power Solutions offers a comprehensive portfolio of premium power supply and control products, systems, solutions and services.
Protect PV.500-PV.800 solar inverter PV park in Möhnesee, Germany
AEG Power Solutions – Competence Center in Warstein-Belecke
Using their tried and proven technologies, AEG Power Solutions is well-placed to deliver smart solutions for photovoltaic and storage systems. The heart of any plant is the central inverter, designed to convert DC power from the solar panels to AC power for the utility grid. AEG Power Solutions offers different models of central inverters, named the Protect PV.250, PV.500, PV.630 and PV.800, which have an outstanding conversion efficiency. The basic models of the Protect PV product line are designed for indoor use. More advanced models can be placed outdoors directly. The most advanced models are included as part of the turnkey solutions in containers, abbreviated TKS-C. The TKS-C is a fully integrated solution that has been developed specifically for use in photovoltaic power plants. It comprises: • up to two solar central inverters • switchgear • a medium-voltage transformer • measuring and monitoring components • data communication capabilities
In order to bridge the gap between exploiting power availability at times that cannot be readily predicted and delivering sufficient power at times of demand, AEG Power Solutions has developed a BESS (Battery Energy Storage System) solution. Through its Battery Energy Storage System, AEG PS provides a solution that meets the needs of a rapidly changing energy market. The components that make up the BESS are housed in combined containerized units with control managed via the AEG PS control unit, which can be operated locally on site or remotely via the Internet. The power electronics that are used in the BESS have been developed specifically for complex, modern grid applications and offer customers the benefit of established, robust, reliable and field-tested equipment.
AEG Power Solutions GmbH Address: E mil-Siepmann-Straße 32 59581 Warstein-Belecke · Germany Phone: + 49 (0)2902 763-141 Fax: + 49 (0)2902 763-1201 Email:
[email protected] Web: w ww.aegps.com Year founded: 1946
Sales volume: 4 28 million euros (2011, worldwide) Employees: > 1,650 (2011, worldwide)
The total concept is flexible and adjustable to many requirements and is applicable for almost all grid codes worldwide.
Battery Energy Storage System
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Business areas: inverters connection technology planning and grid integration monitoring/supervision software/IT communication services
Bonfiglioli Riduttori S.p.A. Bonfiglioli manufactures and designs power conversion systems from 3 MW turnkey solutions down to 30 kW compact devices, for medium to large commercial and utility-scale installations.
Bonfiglioli offers a worldwide and localized service network.
Bonfiglioli RPS TL
Bonfiglioli Riduttori S.p.A. Address: V ia Giovanni XXIII, 7/A 40012 Lippo di Calderara di Reno – Bologna · Italy Phone: + 39 0516473111 Fax: + 39 0516473126 Email:
[email protected] Web: w ww.bonfiglioli.com Year founded: 1956 Employees: 3,300
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Bonfiglioli RPS Station: turnkey solutions customized for your market
Thanks to the global nature of its distribution network and its wide range of reliable high-efficiency solutions, prestigious international EPCs and IPPs trust Bonfiglioli to supply inverters for largescale photovoltaic installations in Europe, Asia and North America. In 2008, Bonfiglioli supplied its solutions for the world’s largest photovoltaic field at the time (51 MW) in Spain. In 2010, Bonfiglioli supplied inverters for one of Europe’s largest PV fields (70 MW) in Italy and in 2012, a PV field with an output of 60 MW fitted with Bonfiglioli inverters was put into operation in Bulgaria. Bonfiglioli’s long history and consolidated international presence make it a reliable and bankable investor and have allowed the Bonfiglioli Group to contribute to the start-up of major installations in emerging markets.
Bonfiglioli’s RPS Stations, which are available in a vast range of power ratings from 280 to 3,100 kW, provide turnkey solutions for complete photovoltaics field management for all large-scale groundmounted installations. RPS Stations are produced and tested directly at the plant to ensure the highest standards of quality and efficiency along with reduced costs. As a result, customers receive a fully equipped, ready-to-connect system in impressively short times. The RPS TL modular inverters at the heart of every Bonfiglioli RPS Station guarantee highest system yields and excellent international grid code compatibility thanks to the modular engineering and German technology that distinguish all Bonfiglioli inverters. In-depth understanding of markets and market dynamics, 17 commercial subsidiaries, four photovoltaic production centers on three continents and a wide range of high-tech inverters make Bonfiglioli a long-standing and risk-free industry player for photovoltaic field developments anywhere in the world.
Business areas: inverters monitoring/supervision connection technology storage technologies
Bosch Power Tec GmbH Solar Power Day and Night The Bosch Group is a leading global supplier of technology and services, active in the fields of automotive technology, energy and building technology, industrial technology and consumer goods.
The VS 5 Hybrid regulates energy flows and reaches a household selfsufficiency level of 75% and more.
The VS 5 Hybrid is a fully-integrated system and has already received numerous awards.
Bosch Power Tec GmbH is a 100% subsidiary of Robert Bosch GmbH and was founded in January 2011. The business purpose is the development and sale of electronic power components for use in the renewable energy industry. The portfolio includes highly-efficient solar inverters, pre-fabricated inverter stations, system management solutions and pioneering electricity storage technologies. Extensive service and maintenance contracts for every product group enhance the Bosch Power Tec range. Solar storage The VS 5 Hybrid comprises a transformerless 5 kW inverter, a lithium-ion battery and a management system. The storage of solar power makes it possible to ensure one’s own needs are met with PV electricity even outside of daylight hours. The energy is taken from the PV system and fed directly into the power grid, taken from the storage system or simultaneously made available from both sources. Grid power is only used when not enough energy can be made available this way. The system also operates self-reliantly in the event of a power failure.
With the VS 5 Hybrid system, the selfsufficiency level of a four-person household can be increased to 75% and more. The VS 5 Hybrid is the only system in the world that can supply solar energy to both single- and three-phase households at any time, day or night. Made in Germany We have been producing and developing our products exclusively in Germany for more than 30 years, and rely on highquality materials and industrial components in our development work – helping us to ensure that our products will last for a long time even under harsh conditions.
Bosch Power Tec GmbH
Address: S achsenkamp 5
20097 Hamburg ∙ Germany
Phone: +49 (0)391 813 3030 Fax: + 49 (0)40 6450 2101
Email:
[email protected] Web: w ww.bosch-power-tec.de Year founded: 2011 Employees: 180
The VoltApp is the mobile iPhone and iPad monitoring solution for solar installers and system owners.
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Business areas: inverters monitoring/supervision software/IT
Danfoss Solar Inverters Danfoss Solar Inverters – Smart Solutions We supply reliable, flexible and user-friendly inverter solutions for residential, commercial and large-scale applications worldwide.
The TLX Pro series offers control of up to 100 inverters from a single self-designated inverter.
TLX Pro powers the 80+ MW facility in Eggebek, Germany; one of the largest PV plants in the world
Danfoss Solar Inverters A/S Address: U lsnaes 1 6300 Graasten · Denmark Phone: + 45 7488 1300 Email:
[email protected] Web: w ww.danfoss.com/solar Year founded: 1933
Employees: 23,000 (worldwide)
Danfoss is a global company with over 40 years of experience in power electronics. Danfoss Solar Inverters develops and manufactures a comprehensive range of grid-connectable, photovoltaic inverters for all PV applications, and is represented in more than 20 countries worldwide. The Danfoss inverter range (from 2 to 15 kW) provides the smart solutions needed to develop your PV set up. • The TLX series 3-phase transformerless inverter range from 6 to 15 kW. • The DLX series 1-phase transformerbased inverter range from 2 to 4.6 kW. Solutions for all PV system ranges Planning a PV system that reliably delivers maximum yield at minimum cost is possible with a Danfoss solar inverter solution. Whether you are designing a residential, commercial or large-scale power plant, a fully optimized system will raise the energy yield while lowering system costs.
DLX features an integrated web server, high efficiency and access to real-time data via the Danfoss SolarApp.
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Residential solutions Both the DLX and TLX series offer an inverter and web server in one solution. Just one inverter is needed for installations up to 17 kWp.
Commercial solutions The TLX series with three independent maximum power point trackers (MPPT) and a high voltage level is designed to achieve the layout flexibility needed to maximize the energy yield of the area available – especially when encountering complex roofing challenges. Large-scale solutions The TLX series is also perfect for largescale applications thanks to the ability to reduce the effects of shading, allowing for more PV per m2, and closer placing of module rows. Reliable and proficient partner From planning and installation to troubleshooting and service – in addition to having one of the industry’s most experienced solar support teams, Danfoss offers clean and efficient solar energy solutions for all applications. For a comprehensive overview of our products and services, please visit us at www.danfoss.com/solar.
Business areas: inverters monitoring/supervision storage technologies
Diehl Controls – PLATINUM® GmbH PLATINUM®: Premium Brand for Photovoltaic Inverters PLATINUM® offers inverter technology at the highest performance level. DIVE® technology, SiC components and RAC-MPP® for rapid MPP location make PLATINUM® inverters, which boast peak efficiencies in excess of 98%, rank among the best. PLATINUM® inverter manufacturing plant
Pulls out a cool 98.4% – the PLATINUM® R3 inverter.
PLATINUM® string inverters in the 2 to 22 kW power range offer the right solution for every system size and are manufactured to the highest quality. Intensive quality testing ensures a particularly low failure rate, producing robust components. The ten-year exworks warranty and the option to extend it to 20 years for the majority of all products is standard for PLATINUM®.
PLATINUM® products also comprise intelligent devices to monitor the power output of photovoltaic systems. The WebMaster Home optimizes private consumption and visualizes any number of consumers, enabling intelligent energy management. The PLATINUM® battery, which stores solar energy and makes it available 24/7, supplements high-quality solar technology. With capacities ranging from 4.6 kWh to 41 kWh, it is compatible with all PLATINUM® photovoltaic systems or can be integrated into existing systems.
PLATINUM® GmbH (formerly known as Diehl Controls) Address: P fannerstraße 75 88239 Wangen · Germany Phone: + 49 (0)7522 73-700 Fax: + 49 (0)7522 73-710 Email:
[email protected] Web: w ww.diehl.com/photovoltaics Employees: 90
PLATINUM® places emphasis on customer service as well as product quality. The company therefore runs regular training events for dealers, sales staff and installation engineers in its headquarters in Wangen im Allgäu. PLATINUM® experts help customers to find the right solution for difficult challenges – competently and quickly, either over the telephone or on-site.
PLATINUM® headquarters in Wangen im Allgäu
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Fronius Deutschland GmbH
Business areas: inverters monitoring/supervision software/IT
Fronius: Innovative Products and Technical Advances The highest possible level of quality is at the forefront of all of Fronius’ activities and manifests itself in powerful, grid-connected inverters and the wide range of system monitoring products. The Fronius Agilo central inverter can be completely installed and maintained by the installer.
Fronius Galvo – specializing in private consumption
The Fronius Active Energy Tower operates without generating any CO2 emissions.
Fronius Deutschland GmbH Address: A m Stockgraben 3 36119 Neuhof-Dorfborn · Germany Phone: + 49 (0)6655 91694-0 Fax: + 49 (0)6655 91694-50 Email:
[email protected] Web: w ww.fronius.de Year founded: 1993 Employees: 210
Fronius, with its headquarters based in Austria, has been researching new technologies for converting electrical energy since 1945. That’s more than 60 years of experience, progress and continuous innovation. Fronius’ Solar Electronics division has been involved in photovoltaics since 1992 and sells its products through a global network of sales partners.
Innovative products and new technologies In the development of PV inverters, Fronius has thought out new technologies, searched for innovative solutions, and has found completely new answers. The result: highly functional grid-connected inverters, which interact optimally with all solar modules.
Producing and selling quality As a quality leader, Fronius develops and produces high-performance inverters for grid-connected solar power systems from 1 kW upwards. The product range is complemented by an extensive range of components for professional system monitoring, data visualization and analysis – all available as stand-alone product add-ons.
Additionally, Fronius also provides userfriendly data communications systems for individual PV system monitoring. The hardware components are quick and easy to install, the software easy to operate. Customers can access their PV system’s performance data anytime and anywhere via the internet, smartphones or tablet PCs.
Living sustainably Using renewable energy and protecting resources are important parts of the corporate culture at Fronius. The Fronius Active Energy Tower in Wels (Austria) with its active energy design ensures that the building operates without generating any CO2 emissions. The climate-protection façade provides shade while simultaneously generating energy that can be used in the tower.
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Business areas: inverters monitoring/supervision storage technologies
GoodWe GoodWe Solar Inverter – World-Class Supplier of PV Distributed Energy GoodWe is a rapidly developing inverter manufacturer. With smart monitoring solutions, their high-performance solar inverters have been widely applied in residential and commercial rooftop systems as well as power plants.
“A compact, unadorned 4 kW inverter from China has passed the PHOTON test with a more than respectable result: Its efficiency is as impressive as its operation is convenient.” Photon International
GoodWe inverter family: from 1.5 kW to 500 kW
GoodWe has so far already developed and produced six series of solar inverters (the SS, DS, DT, DI, PB and MT series), ranging from 1.5 to 500 kW. The maximum conversion efficiency reaches up to 98.8%, while MPPT efficiency is greater than 99.5% and THDi is less than 1%, representing the world-leading level. High-performance inverter GoodWe solar inverters are designed in Germany and assembled in China. At the end of 2012, GoodWe’s GW4000-SS inverter passed the Photon Test and was awarded a “Double A” evaluation, as well as being ranked world number one in the 4 kW series and among the world’s top three in the 1.5–5 kW series. Our products have so far obtained many international certificates, such as the CGC, CEI 0-21, VDE, TÜV, CE, G83, G59 and SAA certificates, and have become listed by bodies and authorities such as the CEC, Western Power and the Danish government. New arrival: hybrid inverter The GoodWe PB series bidirectional energy-storage inverter can control the flow of hybrid energy and can be used in both on-grid and off-grid PV systems by switching it automatically or manually
according to the system’s working situation. During the day, the PV plant generates electricity which can be provided to the loads, fed into the grid or used to charge the battery. The energy stored can be released when the loads require it during the night. Additionally, the power grid can also be used to charge the storage devices via the inverter. Smart monitoring system We provide our customers with a flexible monitoring solution. Our customers can log in to our monitoring website or use smartphone apps to check power plant information. Advantages of internet monitoring: • two basic monitoring choices: Wired RS485 or Wi-Fi • automatic transmission of data to our global PV station monitoring web server via the internet • support with iOS/Android apps, rich and visual graphic display • equipped with data collector designed to ensure data security for enterprises
GoodWe Europe Address: L ise-Meitner-Straße 1-13 (Haus 1) 42119 Wuppertal · Germany Phone: + 49 (0)202 94228160 Fax: + 49 (0)202 94228161 Email:
[email protected] Web: w ww.goodwe.de Year founded: 2 010 Employees: 260
GoodWe Australia
Address: M elbourne, VIC · Australia Phone: + 61 432 180 156
Email:
[email protected] Web: w ww.goodwe.de
GoodWe China
Address: N o.189 Kunlunshan Rd., SND,
Suzhou, 215163 · China
Phone: + 86 512 6239 6771
Phone: + 86 512 6239 7972
Email:
[email protected] Web: w ww.goodwe.com.cn
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Business areas: CPV modules module junction boxes inverters housing MLPM monitoring/supervision connection technology
W. L. Gore & Associates GmbH Secure Sensitive Electronics with GORE® Protective Vents With proven expertise in the solar industry for more than ten years, Gore has set new standards for reliable, high-performance venting solutions that protect sensitive electronics in solar equipment.
GORE® Protective Vents improve reliability, allowing continuous airflow while blocking contaminants.
GORE® Protective Vents improve the performance of your product under all conditions.
W. L. Gore & Associates GmbH Address: W ernher-von-Braun-Straße 18 85640 Putzbrunn · Germany Phone: + 49 (0)89 4612-2211 Fax: + 49 (0)89 4612-2302 Email:
[email protected] Web: w ww.gore.com Year founded: 1958
Employees: 10,000
Reliable performance and ensuring the long life of your product GORE® Protective Vents improve the performance and extend the life of your solar components by equalizing pressure, reducing condensation and preventing contamination. Constructed of a unique membrane with billions of pores 700 times larger than an air molecule, GORE® Protective Vents allow air to flow freely in and out of the housing, which prevents stress on seals. With continuous diffusion of moisture vapor, these vents also reduce condensation that compromises components. At the same time, Gore’s vents protect sensitive electronics because the membrane pores – which are 20,000 times smaller than a drop of water – serve as a barrier against water, dirt and debris. Ensure the reliability and long-lasting performance of your solar components with GORE® Protective Vents.
Available in many sizes and forms, GORE® Protective Vents are easily integrated into your enclosure.
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Optimal solution for many applications GORE® Protective Vents are engineered with screw-in, snap-in or welded membrane constructions that meet solar industry standards. This versatile portfolio simplifies integration into the design of your product, be it a junction box, string combiner box, micro/string inverter, CPV module or tracking equipment. Select from multiple options to choose the best GORE® Protective Vent for your product design. The global solution As a technology-driven company focused on innovation, Gore has delivered venting solutions for millions of rugged applications worldwide over the past 30 years. With sales and R&D offices throughout the world, and manufacturing sites in the USA, Japan, China and Europe, Gore delivers more than a venting product – our engineers will work with you from the initial product concept through rigorous testing and integration into the manufacturing process. Choose Gore as your partner for reliable performance.
Business areas: inverters monitoring/supervision software/IT
Ingeteam Power Technology S.A. “The formula of the new energy: i + c” At Ingeteam each project is addressed from the concept of i+c – innovation to develop the optimal solution and commitment to provide an excellent service.
Ingeteam Smart House, a global energy management solution for residential and industrial use
PV on-roof installation at the Lamborghini factory (Italy) powered with Ingecon® Sun inverters
With manufacturing facilities in Spain, China and the USA, and subsidiaries in Germany, Italy, France, the USA, the Czech Republic, Poland, Brazil, Mexico, South Africa, China, Chile and India, Ingeteam can satisfy the needs of its clients worldwide. Furthermore, Ingeteam’s Service Division provides operation and maintenance services to more than 400 MW of solar PV installations worldwide. In the field of solar energy, Ingeteam has already overcome technology, and regulatory and integration roadblocks to offer holistic electrical equipment solutions in many solar installations operating throughout the world. Ingeteam’s latest innovations include the new Ingecon® Sun Power Max 1 MW central inverter for large-scale PV installations, which reaches an output power of 1,019 kW and a maximum efficiency of 98.8%. In order to meet households’ new energy needs, Ingeteam has also just presented the Ingeteam Smart House concept, a global energy management solution for residential and industrial use that allows for increased on-site consumption. Moreover, Ingeteam has launched the new Ingecon® Sun 1Play (2.5 to 10 kW) and Ingecon® Sun 3Play (10 to 40 kW) inverter
families with improved features that include higher efficiency levels. Finally, the Ingecon® Sun Training platform offers a wide range of on-site training courses and live webinars aimed at professionals in the PV sector. Ingeteam is a global corporation specialized in six different sectors (energy, industry, marine, traction, basic technologies and services) that are all customer oriented and based on power and control electronics, electrical machines and application engineering. Thanks to its divisionbased structure and sustainable growth policy, Ingeteam enjoys a privileged, competitive position and has strongly established itself as one of the leading companies in the electronics and electrotechnical sector.
Ingeteam, S.A.
Corporate Headquarters
Address: P arque Tecnológico de Bizkaia,
Edificio 106 48170 Zamudio-Bizkaia ∙ Spain Phone: + 34 944 039 710 Fax: + 34 944 039 800 Web: w ww.ingeteam.com
Ingeteam Power Technology, S.A.
Energy Division Headquarters
Address: A vda. Ciudad de la Innovación, 13
31621 Sarriguren-Navarra ∙ Spain
Phone: + 34 948 288 000 Fax: + 34 948 288 001
Email:
[email protected] Web: w ww.ingeteam.com
Year founded: 1972 (Ingeteam Group)
Employees: 3,000 (Ingeteam Group, world-
wide)
The Ingecon® Sun 1Play inverter family, able to withstand extreme temperatures
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Business areas: module junction boxes connection technology
KOSTAL KOSTAL – Intelligent Photovoltaic Solutions for Every Requirement As part of the KOSTAL group – a family-owned and internationally active company from Germany with more than 100 years of tradition – KOSTAL Industrial Electronics and its sales company for solar inverters KOSTAL Solar Electric offer comprehensive solutions in the field of photovoltaics. In this sector KOSTAL focuses on solar module connection technology and its PIKO inverters.
Hagen/Westphalia – home of KOSTAL Industrial Electronics
Fully automatable SAMKO 100 04 PV junction box with integrated cable holder
Smart connections.
KOSTAL Industrie Elektrik GmbH (KOSTAL Industrial Electronics) Address: L ange Eck 11 58099 Hagen · Germany Phone: + 49 (0)2331 8040-4800 Fax: + 49 (0)2331 8040-4811 Email:
[email protected] Web: w ww.kostal.com/industrie Year founded: 1995
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KOSTAL Industrial Electronics and KOSTAL Solar Electric – simply a smart connection The KOSTAL “Smart connections.” philosophy is based on four competitive advantages: KOSTAL family, real partnership, quality-offensive thinking and future programs. The interaction of these factors brings about smart connections between KOSTAL and its partners, as well as between the products and the product benefits. These connections are designed to obtain success in the long run.
PV junction boxes – smart connections for solar modules KOSTAL Industrial Electronics is able to draw on the extensive experience in the development and production of solar module connection technology that it has been garnering since 1998. Taking into account the different customer requirements, a comprehensive portfolio of customer-specific and universally usable solutions has been acquired. This wide array of products ranges from standard solutions to fully automatable options. KOSTAL has developed innovative concepts for solar module connection technology, such as leadframe technology, and these have become firmly established in the market. To round off the product range KOSTAL offers PV plug connectors – a reliable solution for the whole PV system.
KSK 4 PV plug connector
PV module connection technology from KOSTAL is always a smart connection – today, tomorrow and in the future.
Business areas: inverters monitoring/supervision storage technologies communication services
PIKO Data Communicator
PIKO Battery Inverter with integrated energy management system
The KOSTAL team – a strong partner
PIKO inverters: flexible, communicative, practical KOSTAL Solar Electric’s product range comprises PIKO-brand single-phase and three-phase inverters in various power classes. The advantages of PIKO inverters can be described using the following adjectives: flexible, communicative and practical. The high input voltage range and up to three independent MPP trackers provide maximum benefits and flexibility in the field of application as well as simple handling. All PIKO inverters include a comprehensive communication system and an integrated data logger which stores the data of the PV system for up to a year. Further communication options range from the provision and monitoring of all important data – with the aid of the integrated interfaces – to the control of external devices. The PV system can be monitored both locally and remotely using the PIKO Data Communicator for monitoring via digital picture frames, the web server,
the PIKO Master Control, and the PIKO Solar Portal. In 2013, KOSTAL will start selling its PIKO Battery Inverter with an integrated energy management system. Taking economical and technical aspects into consideration, the system regulates whether the energy produced by the PV system will be fed into the public grid, stored temporarily in the battery or used for energy consumption. Via local distribution companies in Spain, Italy, France and Greece, KOSTAL Solar Electric offers on-site sales, service and training in the local language. The KOSTAL seminars provide customers and partners new perspectives by providing the latest information on gained experience and new developments to ensure they are up-to-date and to allow for the exchange of knowledge.
KOSTAL Solar Electric GmbH Address: H anferstraße 6 79108 Freiburg i. Br. · Germany Phone: + 49 (0)761 47744-100 Fax: + 49 (0)761 47744-111 Email:
[email protected] Web: w ww.kostal-solar-electric.com Year founded: 2 006
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Business areas: inverters housing power plant control monitoring/supervision software/IT communication services
LTi REEnergy The Best Possible Plant Efficiency – with PVmaster Inverters from LTi REEnergy
CEO Dr. Wolfgang Lust
On the “roof of the world” in Tibet, at an altitude of 4,000 meters, PVmaster II units are delivering optimum yields.
“Vision always opens up new perspectives.” – CEO Dr. Wolfgang Lust LTi REEnergy GmbH Address: H einrich-Hertz-Straße 18 59423 Unna · Germany Phone: + 49 (0)2303 779-0 Fax: + 49 (0)2303 779-397 Email:
[email protected] Web: w ww.lt-i.com Year founded: 1971 (LTi Group)
Sales volume: > 150 million euros (LTi Group) Employees: > 1,000 (LTi Group)
PVmaster (TT, EN and EM) Container Station and PVmaster Concrete Station from LTi REEnergy
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LTi REEnergy belongs to the LTi group of companies, which has been successfully developing inverters for a wide variety of applications and producing them in large numbers for over 40 years. The group enjoys international success with over 1,000 employees worldwide, branch offices on three continents, as well as more than 30 sales and service points. LTi has always stood for technologically innovative products of the highest quality. It has performed pioneering work in the field of energy technology right from the start, and will continue to do so in the future. The range of products includes: • central inverters from 40 to 300 kW for photovoltaic systems (roof systems) • central inverter stations from 200 kW to 2.4 MW for photovoltaic power plants, as well as container stations • electronics and active power supply in mini CHP plants • ORC systems to generate power from process and waste heat • robust pitch systems for rotor blade adjustment in wind turbines
The photovoltaic portfolio consists of a variety of topologies and services, which enable LTi REEnergy to be prepared for varying regional requirements worldwide, standards and regulations, demanding environmental conditions or difficult logistical and transport situations. Depending on the requirements and conditions, the “PVmaster” central inverter series can be used in grid-connected operations or in a variety of standalone applications. To guarantee on-going product optimization, LTi developers have succeeded in developing a new inverter topology with a peak efficiency of 99.2%, which is almost certainly unrivalled anywhere in the world to date. What is special about the new technology is that the increase in efficiency has not been achieved by using material-intensive circuits.
Business areas: inverters monitoring/supervision connection technology storage technologies charge regulators communication services
Mastervolt International BV Maximum Yield – Worldwide For more than 20 years, Mastervolt has been developing, manufacturing and distributing technologies for independent electricity generation. Mastervolt launched its first photovoltaic inverter, the SunMaster 130, as early as 1993, making it a true pioneer in the solar industry.
IntelliWeb: online overview of your PV system
Soladin web inverter
Today, Mastervolt has branches on all continents of the world. Since January 2011, Mastervolt has been a subsidiary of Actuant, a globally active technology group. The association with a financially strong, listed corporation will allow Mastervolt to continue its growth course and to bring innovative products and technology to the market even faster. Flexible technology optimized for installers’ needs Mastervolt supplies photovoltaic inverters ranging in output from 0.5 kW to 30 kW. Mastervolt’s IntelliConcept, which is used in the company’s devices, is designed to achieve 5 to 10% more yield, even in variable weather conditions. This allows a variety of plant sizes and different types of solar modules to be covered with relatively few inverter types. This flexibility reduces training times and storage requirements for installers and distributors alike. Owing to their low weight and smart design, Mastervolt products are optimized for easy installation. Business operations tailored to collaboration Mastervolt has also tailored its business operations to achieve the best possible collaboration with partners and installers.
The company guarantees a unified and transparent distribution structure. All products, including inverters for largescale solar power plants with capacities of several MW, are solely available through Mastervolt’s distribution partners.
AM
IntelliStart Delivers additional yield in the early morning and the late evening. IntelliCool Stable high efficiency and constant high power.
Mastervolt International BV Address: S nijdersbergweg 93 1105 AN Amsterdam ZO ∙ The Netherlands Phone: + 31 (0)20 3422-100 Fax: + 31 (0)20 3422-169 Email:
[email protected] Web: w ww.mastervolt.com Year founded: 1 991 Employees: 120
IntelliTrack Additional yield by tracking fast weather change. IntelliPeak Maximizes efficiency where it’s needed most. IntelliGrid Stable operation during small grid disturbances. IntelliString Up to 80% reduction of cable loss. IntelliShade Maximizes production even under shaded conditions. IntelliWeb Integrated monitoring for early warning on system fault.
Mastervolt IntelliConcept: 5 to 10% more yield
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Business area: monitoring/supervision
meteocontrol Independent Consulting and Intelligent Solutions for Your PV and Wind Projects
meteocontrol is a technological leader and has been one of the most innovative service providers in the PV energy sector for more than 30 years.
meteocontrol GmbH Address: S picherer Straße 48 86157 Augsburg · Germany Phone: + 49 (0)821 34666-0 Fax: + 49 (0)821 34666-11 Email:
[email protected] Web: w ww.meteocontrol.com Year founded: 1976 Employees: 120
Central recording of all system data
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Dates and facts The company’s headquarters is in Augsburg/Germany; further offices are located in Moers/Germany, Milan/Italy, Madrid/ Spain, and Lyon/France. Its sister company, meteocontrol North America, was set up in 2010 for the North American market. 120 employees now work at these sites. Independent consulting The competence and experience of independent experts are indispensable in securing investments and minimizing risks. As a consultant and technical service provider, meteocontrol supports PV projects with technologically leading solutions throughout the entire project life-cycle, such as reliable forecasts which incorpo-
rate all relevant parameters and form the basis for sound and solid planning. An extensive range of services enables implementation and allows meteocontrol to ensure proper planned commissioning for large-scale projects. Since September 2012 meteocontrol is able to use a qualified rating system to measure the quality and the risk of yield loss of a PV project. Competence in energy and weather meteocontrol is able to draw on the most modern information technology and years of experience in monitoring renewable systems: 31,000 PV systems with a total power of over 6.7 GWp are currently monitored. With a global market share of around 15% in professionally monitored systems, meteocontrol is a global market leader in this segment. meteocontrol’s product portfolio now offers monitoring solutions for every operation size – from private systems through to solar power plants. The recording and analysis of highly valid solarization data from satellite measurements enables precise energy forecasts for PV systems. These solar power forecasts allow energy suppliers and network operators to precisely plan their network loads and their PV share of the energy mix.
Business areas: module junction boxes connection technology
Multi-Contact AG The Original MC3 & MC4 Connectors for Efficient PV Systems Multi-Contact is one of the leading manufacturers of PV connector systems worldwide with more than 15 years of experience in the field, offering solutions for all kinds of PV installations. Multi-Contact’s competence center for photovoltiacs in Essen, Germany
PV connector MC4PLUS, designed for the use in high-volume cable assemblies
Type of MC Multilam, based on the torsion spring principle
Multi-Contact offers a broad range of products for the PV industry such as the original MC3 & MC4 connectors, solar cables, junction boxes and customized solutions, providing complete cabling solutions for components ranging from the panel to the inverter. The MC Multilam Technology ensures high efficiency and a long product life. Often exposed to rough climates and demanding environments, PV installations require resilient, efficient and long-lasting components, while costs and the time taken by certain processes need to be reduced to keep the system profitable. Without compromising quality, we offer timesaving connection solutions for all kinds of PV installations, from small off-grid systems to large-scale PV power plants.
Multi-Contact AG headquarters, Switzerland
Quick installation and easy maintenance With our MC4 and MC4PLUS connectors, the entire installation can be cabled with a single system. The preassembled MC4PLUS (IEC 1500VDC, UL 1000VDC) is particularly suitable for module manufacturers and installations with large cable cross sections. The original MC4 is available both preassembled and for on-site assembly. The new Y-test branch cables allow direct measuring under tension without interrupting the strings. Reliable in all environments PV installations need to withstand UV radiation, wind, rain, snow and often dramatic changes in temperature, requiring the reliability of all components. This is why MC subjects its products to various environmental tests: The MC4 connectors and Westlake junction box have successfully passed ammonia resistance tests simulating stable climate conditions over a 20-year period, as well as salt mist spray tests (DIN EN 60068-252:1996), proving them suitable for use in rural and coastal areas. The MC4 and MC4PLUS connectors conform to protection categories IP65, IP67 and IP68 (1m/1h), while the Westlake is IP65 protected. All products are IEC and UL recognized.
PV-JB/WL junction box for crystalline modules
Multi-Contact AG Address: S tockbrunnenrain 8–12 4123 Allschwil · Switzerland Phone: + 41 (0)61 306 55-55 Fax: + 41 (0)61 306 55-56 Email:
[email protected] Web: w ww.multi-contact.com Year founded: 1 962
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Business areas: inverters housing power plant control MLPM monitoring/supervision LOP connection technology planning and grid integration software/IT
Nidec ASI S.p.A. Nidec ASI, a Destiny with Roots That Go Back More than 160 Years Nidec ASI operates in the solar industry with the complete dedication and customer orientation that result from its know-how and wealth of experience.
Robust containerized solutions for harsh environments
Part of a 2 MW PV plant in Italy
Nidec ASI S.p.A.
Nidec ASI S.p.A. Address: V iale Sarca, 336 20126 Milan · Italy Phone: + 39 02 6445-1 Fax: + 39 02 6445-4401 Email:
[email protected] Web: w ww.nidec-asi.com Year founded: 1853 Employees: 1,500
Nidec ASI was formed in December 2012 following the acquisition of Ansaldo Sistemi Industriali Spa (ASI) by Nidec Corporation. Over the past century and a half, ASI has specialized in providing innovative power control and system solutions that have satisfied hundreds of customers worldwide. The company’s strength lies in working together with its customers to develop innovative solutions that fully fit customers’ business and plant goals, allowing them to achieve a rapid return on investment. Since the launch of its plug-and-play solution for large-scale solar plants, which gained the appreciation of the market due to its outstanding performance and reliability, Answer Drives GS SolarPower has been sold worldwide.
The Answer Drives GS SolarPower for large-scale solar power stations
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The Answer Drives GS SolarPower ensures extremely low harmonics, maximizing grid stability and ensuring near unity power factor and a European Efficiency of over 98%. The Answer Drives GS SolarPower inverter family comprises four classes of inverters available in two versions – low voltage (400 V) for commercial installations and medium voltage (10/15/20 kV) for utility applications. The inverters are CE marked according to EMC European Directive 2004/108/CE (compliance with EN 61000-6-3 and EN 61000-6-4) and Low Voltage Directive 2006/95/CE. The grid connection meets CEI 0-21, CEI 0-16 and Real Decreto RD1663/2000 standards. The interface is user-friendly and intuitive. In response to the high demand for solar plants in extremely hot climates, Nidec ASI offers a water-cooled version of its inverter station. About Nidec Corporation From its founding in 1973, the Nidec Group’s goal has been to become number one in electric drive solutions, while maintaining a strong focus on electric motors. With a work force of approximately 98,000 and operations in more than 18 countries, Nidec, which is headquartered in Kyoto, Japan, has been quoted on the New York Stock Exchange since 2001.
Business areas: housing LOP connection technology
OBO BETTERMANN GmbH & Co. KG Combined Protection with the ProtectPlus Program for Photovoltaic Installations Whether sun, rain, heat, cold, lightning or surges, a PV installation must be able to withstand many factors during its lifetime. OBO’s ProtectPlus systems provide effective protection and ensure reliable operation for many years. PV installation with insulated isCon® lightning conductor
OBO fire protection bandages
Protecting the network of cables The professional installation of our cable routing systems and connection and fastening systems ensures a fault-free, longlasting connection between PV components. The OBO product range comprises cloes cable tray, wide span tray and mesh cable tray systems with the TrayFix mounting adapter for flat roofs.
ProtectPlus provides safe protection from environmental influences: • protects the electrical installation against mechanical loads • protects the installation against direct lightning strikes • protects the installation against surges • protects the installation against fire
Protection against surges Our transient and lightning protection systems protect PV installations against damage and breakdowns caused by lightning strikes and surges. The lightning and surge arrester up to 1000 V DC and the surge protective devices for AC and data solutions protect the investment against damages.
OBO offers solutions from external lightning and surge protection systems through to proper cable routing with cable support systems. OBO fire protection systems fulfill the installation requirements. Coordinated protection and the ProtectPlus system kit from OBO.
OBO BETTERMANN GmbH & Co. KG Address: H üingser Ring 52 58710 Menden · Germany Phone: + 49 (0)2373 89-0 Fax: + 49 (0)2373 89-238 Email:
[email protected] Web: w ww.obo-bettermann.com Year founded: 1 911
Employees: approx. 3,000
Protection against the spread of fire Our fire protection systems protect against the spread of fire, heat and smoke. Combined protection Combining our systems properly provides all-round protection for small, large and free-standing installations alike. ProtectPlus – comprehensive protection for PV systems
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Business areas: module junction boxes power plant control monitoring/supervision LOP connection technology software/IT communication services
Phoenix Contact GmbH & Co. KG Comprehensive Solutions for Optimized PV Operation Phoenix Contact is a worldwide market leader for components, systems and solutions in the fields of electrical engineering, electronics and automation. The automation specialist has established itself internationally as a reliable partner for the PV industry. Solarcheck measures the electrical voltage and current of up to eight strings.
The plug-in VALVETRAB surge protection protects PV systems reliably against damage from lightning strikes, for example.
Phoenix Contact GmbH & Co. KG Address: F lachsmarktstraße 8 32825 Blomberg · Germany Phone: + 49 (0)5235 3-00 Fax: + 49 (0)5235 3-41200 Email:
[email protected] Web: w ww.phoenixcontact.com Year founded: 1923
Sales volume: 1 .59 billion euros
Employees: 12,800 (worldwide)
The family business employs more than 12,800 people worldwide and achieved a turnover of 1.59 billion euros in 2012. The headquarters are located in Blomberg (North Rhine-Westphalia) and Bad Pyrmont (Lower Saxony). Seven companies belong to the Phoenix Contact Group Germany. In addition to the seven own production sites, the international group also includes almost 50 sales subsidiaries that are supplemented by 30 representatives in Europe and overseas. In Germany, Phoenix Contact is represented by a sales network of around 80 sales engineers located throughout the country. The automation specialist offers a product range which extends from special plug-in connector systems for distribution and field connection, to PV measuring modules and signal con-
Sunclix plug-in connectors allow consistent and cost-effective cabling from the module to the inverter.
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ditioners, as well as automation technology that includes full lightning and surge protection, and provides suitable and reliable equipment for outdoor PV generators and roof installations. The comprehensive portfolio allows the implementation of turnkey solutions that make it possible to operate PV systems even more profitably. This includes clever connection technology for timesaving assembly as well as innovative controllers for efficient system utilization. The lightning and surge protection for PV systems increases availability and is therefore an essential part of planning new projects. Automatic monitoring by compact controllers provides users with a detailed overview of system power at any time. Special string monitoring modules measure the produced solar current. Via GPRS connections the controller transmits the data to operators anywhere in the world. The portfolio is rounded off with a worldwide team of experienced specialists who help all international users with every matter concerning products from Phoenix Contact.
Business areas: inverters housing power plant control monitoring/supervision storage technologies
Power-One Aiming High with Innovative Solutions for Renewable Energy Power-One is the second largest designer and manufacturer of photovoltaic inverters worldwide. The company’s product portfolio includes inverters for residential applications as well as commercial or large-scale solar parks.
TRIO-20.0-TL TRIO-27.6-TL UNO-2.0-I UNO-2.5-I
Power-One Italy S.p.A.
Power-One Italy S.p.A.
With a 40-year history as a leader in highefficiency and high-density power supply products, Power-One has a broad range of experience that provides a strong foundation for innovation. Over the past four years, the company has continuously expanded its global footprint, operating manufacturing, sales, service and design facilities in Asia, Europe and North America. To serve new and existing locations, Power-One opened additional manufacturing and R&D facilities in Phoenix, Arizona, USA, and in Shenzen, China, in 2011. The company’s aim is to continuously improve its market penetration and performance throughout the world. Broad portfolio for residential and commercial PV installations In addition to being among the first manufacturers to include three-phase string inverters in its portfolio, PowerOne today offers one of the broadest portfolios in this segment, with products ranging from 6 kW to 27.6 kW. Striving to constantly improve the performance of its inverters, the company works to further increase the range of its three-phase AURORA TRIO inverter products for the residential and commercial sectors. The extensive portfolio also includes micro and single-phase inverters.
ULTRA-1400-TL
Best-in-class central inverters for large-scale PV projects With the demand for utility-scale solar parks shifting to the emerging markets, Power-One is prepared to meet their requirements with its central inverter solutions. Its AURORA ULTRA central inverter family is one of the best solutions in its class, offering a robust IP65 enclosure and a modular design concept with 690 Vac output to ensure easy maintenance and maximum energy harvesting.
Power-One Address: 4 0 Calle Plano Camarillo, CA 93012 · USA Phone: + 1 877 261-1374 Email:
[email protected] Web: w ww.power-one.com Year founded: 1 973 Employees: 3,300
Solutions for new applications Power-One is currently also looking into new markets, such as energy storage or smart house applications, and is using its long-standing experience to develop new best-in-class devices, thereby helping to ensure our future energy supply.
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Business areas: inverters monitoring/supervision
REFUsol GmbH High-Efficiency Inverters and Accessories for PV Installations REFUsol is a leading manufacturer of solar inverters. With over 48 years of experience in power electronics, REFUsol is one of the top providers of solar inverters globally and one of the fastest growing companies in this field.
REFUsol central inverter at 70 MW PV plant in Germany
REFUsol string inverters at 4.6 MW PV installation in Belgium REFUsol training center in Metzingen
REFUsol GmbH Address: U racher Straße 91 72555 Metzingen · Germany Phone: + 49 (0)7123 969-0 Fax: + 49 (0)7123 969-165 Email:
[email protected] Web: w ww.refusol.com Year founded: 1965 Employees: 246
Our company Our goal is to maximize the yield of our customers’ photovoltaic installations through our award-winning and costeffective inverters – starting from small roof installations to larger solar power plants. REFUsol is headquartered in Metzingen, Germany, and has international offices in Europe, Asia including China, Japan and India, and the USA, as well as sales and service partners in key strategic photovoltaic markets around the world. Creative freedom and a passion for innovation are among our key corporate principles. REFUsol allows for creative space to drive superior engineering and our employees are passionate about our products and the solar industry in general.
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Our products As a central component in photovoltaic installations, solar inverters play a key role in energy conversion, ensuring profitability. Through our ongoing commitment to technical innovation, our inverters are leading the market when it comes to technology and efficiency, communication and monitoring as well as easy installation and scalability. Whether sold under the REFUsol brand or via an OEM, REFUsol products are ranked top in Photon efficiency factor tests. Our high-quality product portfolio includes string, central and large inverters with a power range of 3.6 kW to 1.3 MW. Available globally, the range can be used in family homes as well as in large-scale solar parks and is suitable for operation in extreme geographical and climatically challenging environments, in an economic and efficient way.
Business area: storage technologies
Saft Li-ion Energy Storage Systems for a New Energy Environment Saft’s battery systems meet every on-grid energy storage need, from grid stabilization in electricity production, to transmission and distribution networks, and on-site consumption in individual homes. Saft’s lithium-ion battery factory in Jacksonville, Florida (USA)
Synerion Storage System (for example: stand-alone, 48 V to 4kWh): Hundreds of units were shipped in 2012.
Building on decades of experience, Saft offers energy storage solutions ranging from kilowatts to megawatts to meet power and energy needs of any size. Saft’s Li-ion energy storage systems are purpose designed to facilitate the effective integration of both small and large-sized renewables, optimal use of transmission and distribution assets, streamlined smart grid management as well as greater options for demand side management. Our storage systems will help you separate supply from demand, while significantly improving grid quality and reliability. Saft makes it easier for you to manage the challenges posed by renewables. Our Intensium® Max containerized energy storage units can smooth out intermittent generation and reduce ramp rates for medium and large solar and wind power plants, ensuring a stable level of power output. Our higher-energy systems also provide capacity firming, making renewable energy a predictable component of a grid operator’s electricity mix.
For on-site consumption applications, our experts can deliver customized battery system kits, based on our standard Synerion® energy storage modules, for use in both OEM power system equipment or as stand-alone solutions. Saft’s scope of supply extends far beyond merely providing Li-ion batteries. We integrate our technology into complete energy storage systems that can include battery management, temperature management and safety functions, as well as power management and power conversion functionalities. Our world-class technology is supported by world-class manufacturing facilities, including one of the sector’s most technologically advanced lithium-ion battery factories, located in Jacksonville, Florida (USA).
Saft
Address: 1 2, rue Sadi Carnot 93170 Bagnolet · France Phone: + 33 (0)149931918 Fax: + 33 (0)149931964 Email:
[email protected] Web: w ww.saftbatteries.com Year founded: 1 918
Employees: 4 ,000 (present in 18 countries)
Intensium® Max containers: Over ten units in the MWh or MW class were shipped in 2012.
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Business areas: inverters connection technology housing charge regulators monitoring/supervision
Schneider Electric The Global Specialist in Energy Management As a global specialist in energy management with operations in more than 100 countries, Schneider Electric is focused on making energy safe, reliable, efficient and green. 6 MW power plant in Osiyan (India)
Solution for residential and small commercial buildings
Solution for large commercial and PV power plants
Schneider Electric SA Address: 3 5 rue Joseph Monier 92506 Rueil-Malmaison · France Phone: + 33 (1)14 1297-000 Fax: + 33 (1)14 1297-100 Web: w ww.schneider-electric.com/solar Year founded: 1836
Sales volume: 2 4 billion euros (2012) Employees: > 140,000
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Schneider Electric provides bankable photovoltaic solutions for installations of any size, together with long-term support from a global company with over 175 years of experience. Schneider Electric products are present at every link in the energy chain, helping customers secure the most efficient solar harvest possible from their installations thanks to qualified and reliable integrated solutions.
For the residential and commercial markets, Schneider Electric offers DC/AC kits and grid-tie, single-phase and threephase inverters ranging from 3 kW to 20 kW. All inverters are reliable, flexible and easy to install. Backed by the company’s global service infrastructure and its expertise in energy management, Schneider Electric inverters are the inverters you can trust for quality and reliability.
For utility-scale and large commercial installations, Schneider Electric provides integrated solutions including a PV Box, array boxes, monitoring & control, and grid connection substations. The PV Box is a factory integrated, tested & validated plug & play power conversion system that, in addition to comprising grid-tie inverters, a DC combiner box, step-up transformer, medium voltage switchgear and other accessories, is adapted to meet local installation conditions. Other items can be added to the package, including the Conext Control monitoring and control solution, climate controls or security equipment.
The Schneider Electric solution for offgrid solar and back-up power installations includes inverter/chargers, charge controllers (with or without MPPT tracking), DC/AC breakers and related accessories. The inverter/charger has unsurpassed surge capacity to prevent drops during power surges. It can be configured for single- and three-phase installations up to 36 kW and allows dual AC inputs for the grid and a generator. For more information about Schneider Electric, please visit www.schneider-electric.com/solar
Business areas: power plant control monitoring/supervision planning and grid integration software/IT
skytron® energy GmbH OUR INNOVATION FOR YOUR BENEFIT How long does it take to find a coin on a soccer field? Even on a surface area of several soccer fields, you should lose neither time nor money. With skytron® energy – Protected investments. Secured yields. Maximized profits.
ArrayGuard® FH combiner box with single PV string protection, which monitors string currents at 100 ms
PVGuard® supervision platform – quick overview of all plants and comparison of important real-time data
How can our energy generation be shaped in a sustainable and profitable way? Providing the answers to this question has been the constant focus of all our operations for 36 years, ever since graduates from the Technical University of Berlin founded the Wuseltronik collective at the end of the 1970s and developed their initial visions for the systematic and cost-efficient use of renewable energy. The pioneering spirit of those days is very much alive at the present-day headquarters of skytron® energy in the BerlinAdlershof Science and Technology Park. Then as now, we consider working closely with scientific research as well as focusing on practical solutions to be essential in this fast-growing industry. Our long-term experience ensures reliable plant monitoring at PV power plants throughout the world. Our power plant control technology and control room software now permanently watch over more than 3.7 GWp of installed PV output. We customize each installation to match the configuration of every individual plant – from precise string-current measurements right through to the con-
trol room presentation, thus allowing for effective supervision of your remote assets. Moreover, skytron® energy provides a complete O&M solution. Our system is compatible with all stan dard inverters on the market, allowing it to be readily adapted to fit your facilities – and to expand with them. In this way your investment costs are protected and the cost-effectiveness of your plant is maintained. The visions of the early days have been transformed into cutting-edge components for PV power plants in the MW sector, which are exactly what the market is looking for. Ensuring your success is at the heart of what we do.
skytron® energy GmbH
Address: E rnst-Augustin-Straße 12
12489 Berlin ∙ Germany
Phone: + 49 (0)30 688 3159-0
Fax: + 49 (0)30 688 3159-99
Email:
[email protected] Web: w ww.skytron-energy.com Year founded: 1977 Employees: 86
ArrayGuard® FH fuse holders for easy-to-handle fuse replacement – fuses on each single PV string
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Business areas: inverters power plant control MLPM monitoring/supervision connection technology planning and grid integration software/IT charge regulators communication services
SMA Solar Technology AG Energy that Changes The SMA Group is the global market leader in solar inverters, an essential component of every PV system, and an energy management group that offers innovative key technologies for power supply systems of the future.
Sunny Home Manager is the control center of SMA Smart Home.
SMA Smart Home: independence from rising electricity prices coupled with convenience
Independence from rising electricity prices – with innovations from SMA
SMA Solar Technology AG Address: S onnenallee 1 34266 Niestetal · Germany Phone: + 49 (0)561 9522-0 Fax: + 49 (0)561 9522-100 Email:
[email protected] Web: w ww.SMA.de Year founded: 1981
Sales volume: 1 .5 billion euros (2012) Employees: > 5,000
SMA inverters as intelligent system managers Inverters convert direct current generated by PV cells into grid-compatible alternating current so it can be used by system operators or fed into the utility grid. As intelligent system managers, inverters also control PV arrays and utility grids. SMA offers an inverter solution for all module types and performance ranges: from small residential PV systems to large-scale PV plants, as well as from grid-connected systems to off-grid and backup systems.
Innovative key technologies Intelligent energy management in the home is an integral component of a decentralized, renewable energy supply. With SMA Smart Home, PV system operators can optimize on-site consumption and gain independence from rising electricity prices. Intelligent energy management in the household The Sunny Home Manager is the control center of the SMA Smart Home. The device learns the household’s typical consumption behavior and combines this information with PV forecast data for solar power generation to ensure optimized consumption. For greater independence from rising electricity prices, SMA offers a highly flexible battery inverter – the Sunny Island. Solar energy can be buffered and used after sunset. The device is suitable for all system sizes, PV inverters and battery types.
Intersolar 2012: SMA’s Sunny Boy 5000 Smart Energy is the first wall-mounted mass-produced PV inverter with an integrated battery.
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SMA is launching Sunny Boy 5000 Smart Energy, as the first mass-produced, wallmounted PV inverter with an integrated battery, this new model will prove particularly valuable for residential PV systems with outputs of up to 5 kW.
Business areas: power plant control monitoring/supervision planning and grid integration software/IT
Solare Datensysteme GmbH Everything You Need to Monitor Your Photovoltaic Plant Solar-Log™ represents PV plant monitoring and management. The Solar-Log™ monitoring system, manufactured by Solare Datensysteme GmbH, has been on the market since 2007. As a market leader, we equip more plants than any other monitoring organization. A worthwhile alternative: direct utilization of self-generated PV energy
Solar-Log™ WEB Commercial Edition ensures reliable plant monitoring and quick repairs in case of failures.
The products we have developed at Solare Datensysteme GmbH are highly user-friendly, requiring zero software installation. Our products scale from small residential up to large commercial applications. Solar-Log™ is compatible with most major inverter manufacturers on the market. With our “Easy Installation” firmware we have automated the inverter detection process as well as the Solar-Log™ WEB (if used) provisioning process. In addition to monitoring and efficiency control, users have the capability to analyze their data either on-site or via the internet. This is accomplished by means of attractive graphical data representations, as well as informative data tables. Control your PV system at any time, wherever you are in the world, using Solar-Log™ APP for Android, iPhone and iPad. Besides cable connectivity, Solar-Log™ also offers wireless connectivity using GPRS, WLAN and Bluetooth. Solar-Log™ even offers a solution for monitoring, controlling and optimizing one’s own solar power consumption as well as Power Management and cos ϕ control.
Solar-Log™ is just as suitable for plants with one inverter as it is for large plants with central inverters and complies fully with technical regulations. For the monitoring of individual strings in very large plants, we also have a high-quality string connector box in our product portfolio.
Solare Datensysteme GmbH Address: F uhrmannstraße 9 72351 Geislingen-Binsdorf ∙ Germany Phone: + 49 (0)7428 9418-200 Fax: + 49 (0)7428 9418-280 Email:
[email protected] Web: w ww.solar-log.com
The Solar-Log™ WEB Commercial Edition web solution offers portal operators a comprehensive plant maintenance interface. The ability to carry out remote configuration and maintenance can save work from having to be performed on site. Error messages are clearly displayed in an overview screen and can be processed using the integrated ticket system and error analysis tool.
Year founded: 2007 Employees: 80
Graphic Solar-Log1000
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Business areas: inverters monitoring/supervision
SolarMax Swiss quality by Sputnik Engineering With its SolarMax brand, the Swiss company Sputnik Engineering AG has focused on solar energy since 1991 and has been a pioneer in the industry ever since. The company develops, produces and sells gridconnected inverters for every solar system.
Swiss quality with high efficiency: SolarMax inverters set standards in terms of quality, reliability, and maximum yields.
Sputnik Engineering AG Address: L änggasse 85 2504 Biel/Bienne · Switzerland Phone: + 41 32 346 56 00 Fax: + 41 32 346 56 09 Email:
[email protected] Web: w ww.solarmax.com Year founded: 1991
Employees: 360 (2012)
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High-quality products made in Switzerland have enabled SolarMax to grow from a start-up into one of Europe’s leading inverter manufacturers.
watts. Furthermore, the product family comprises a series of communication and monitoring solutions, as well as software tools developed for specific assignments.
Thanks to technical know-how, broadly supported knowledge, and more than 20 years of experience in developing inverters SolarMax is able to produce high-quality products. SolarMax inverters are among the industry’s best, offering high efficiency, an intelligent cooling concept, an attractive, easily-mounted casing and a userfriendly graphics display. All inverters are extremely robust and absolutely reliable – and at a convincing price/performance ratio. SolarMax has the right inverter for every application – from photovoltaic systems on single-family homes whose kilowatt output is modest, to the solar power plants whose output is measured in mega
Service at its very best Highly qualified technicians are on hand to advice SolarMax customers on the phone. The service team can trouble-shoot and correct malfunctions either by remote diagnosis or by sending a technician directly to the site. SolarMax carries out specifically designed training measures and courses for its clients – either at its own locations, or directly on-site at the customer’s premises. The SolarMax experts are always available for their customers with advice and support. All requests are answered rapidly, frankly and directly, because SolarMax believes in solid customer service and long-term customer relations.
Business areas: inverters storage technology charge regulators monitoring/supervision software/IT communication services
Steca Elektronik GmbH Steca Solar Electronics – Products and Solutions for an Ecological Future As a leading supplier of products for the solar electronics industry, Steca sets the international standard for the regulation and control of solar energy systems.
Headquarters of Steca Elektronik GmbH in Memmingen
The new Steca Tarom 4545: innovative and functional design
In the three market segments, PV grid connected, PV off grid and solar thermal, the Steca brand is synonymous with innovation and vision. Be it conception, development, production or marketing, we are committed to the highest quality standards. Our focus lies on made-tomeasure solutions for the effective utilization of solar radiation. Furthermore, Steca continually examines the technologies it has developed with a view to simple operation and, consequently, usability for the wide base of the population – worldwide. PV grid connected Together with our range of accessories, StecaGrid inverters represent an innovative family of inverter solutions for gridconnected solar power systems. Whether being used in a small solar power system for a single family home, or an elaborate combined solution for an industrial complex, Steca grid-feeding inverters all have one thing in common: They offer the highest performance along with maximum flexibility and ease of use.
Electronics made in Memmingen – Bavaria
PV off grid Two billion people in rural areas still have no access to an electricity grid. Steca has set itself the target of improving the quality of life of these people. To this end, Steca develops and manufactures top-quality products, which, thanks to their long lifetime, ensure extremely low costs. Today, modern and professional electricity supplies are necessary in every part of the world. For these supplies, the focus is on high industrial demands, flexibility, environmental sustainability and reliability. As an expanding company, Steca Elektronik will continue to bank on Germany and Bavaria as an energy industry center: With a total of 650 employees, the company currently manufactures products for an ecological future on a production area of 29,000 m2.
Steca Elektronik GmbH Address: M ammostraße 1 87700 Memmingen ∙ Germany Phone: + 49 (0)8331 8558-0 Fax: + 49 (0)8331 8558-132 Email:
[email protected] Web: w ww.steca.com Year founded: 1976 Employees: 650
The Steca coolcept inverter has set a new world record in inverter efficiency.
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The Publishers
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Business area: communication services
Solarpraxis AG Engineering, Conferences and Publishing for Renewable Energies Solarpraxis AG is one of the leading knowledge service providers in the renewable energy sector.
The engineering department generates up-to-date knowledge.
B2B magazines and industry guides: The publication range of Solarpraxis includes the complete spectrum of renewable energies
SOLARPRAXIS AG Address: Z innowitzer Straße 1 10115 Berlin · Germany Phone: + 49 (0)30 726296-300 Fax: + 49 (0)30 726296-309 Email:
[email protected] Web: w ww.solarpraxis.de Year founded: 1998
Sales volume: 6 .9 million euros Employees: 70
Since 1998 the Berlin-based company has been providing clients with expertise and professional service in the fields of engineering, conference organization and publishing.
the division provides practical knowledge on market performance, finance and politics. The events are organized in Europe, Asia, North America and in the Middle East.
Engineering The engineering division generates upto-date knowledge, which is then prepared for and presented to manufacturers, wholesalers, planners and trade professionals in a targeted, projectspecific manner. Whether in the area of photovoltaics, solar thermal technology, heat pumps or pellets, clients receive expert and reliable support for reporting, large-scale solar projects, technical documentation, training, expert hotlines and customer service.
Publishing The third and final component of the company’s service portfolio is its publishing department, which boasts two international brands, pv magazine and RENI | Renewables Insight.
Conferences The conference division focuses on organizing high-quality industry events for decision-makers both in Germany and abroad. These events are substantiated, relevant to the market and customer-oriented. Using specialist lectures and topical panel discussions,
Solarpraxis conferences: valued industry platforms
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Since its initial publication in 2008, pv magazine has evolved into the top international photovoltaics magazine for decision-makers. With a global, Chinese and German edition, pv magazine is expanding its position as a global knowledge provider. The media portfolio includes print magazines, e-papers, websites and daily newsletters. The multilingual industry reports under RENI | Renewables Insight respond to the demand for high-quality industry and technology guides. In collaboration with professional associations, information on technology and markets is provided and companies are given an opportunity to communicate expert knowledge about their products and services.
Business area: communication services
Sunbeam Communications Communications for Renewable Energies Since 1998, Sunbeam has offered technical expertise combined with professional communications services for the renewable energy market.
We combine high-quality communications with expertise in technologies and markets in the field of renewables.
Solarwärme Informationen für Vermieter
Solar – so heizt man heute
Information campaign “Heating Today with Solar Energy”
We provide profound market insights together with top-quality contacts to German industry associations, political decision-makers and the press. Public relations Sunbeam supports you in establishing and expanding your communications with customers and the general public. We offer high-quality consultancy services for companies, associations and ministries, and provide strong conceptual skills for the development of PR campaigns.
Communication design Our designers develop key elements for visual communication between your company and your customers. Our technical illustrations allow a clear visual presentation of your products. We specialize in editorial design for high-quality print products including catalogs and journals.
Sunbeam GmbH Address: Z innowitzer Straße 1 10115 Berlin · Germany Phone: + 49 (0)30 726296-300 Fax: + 49 (0)30 726296-309 Email:
[email protected] Web: w ww.sunbeam-communications.com Year founded: 1 998 Employees: 19
New media Sunbeam plans and implements your website project using barrier-free, useroptimized designs. We offer extensive expertise in TYPO3, one of today’s leading open source content management systems for websites. Members of our team have published widely-distributed and much-quoted books on the design and implementation of websites.
As a full-service partner we support you in managing your cross-media communications.
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Important Notice, Picture Credits & Sources Important notice
This brochure, all parts thereof and the website are protected by copyright. The reproduction, alteration and any other type of use of the brochure or parts thereof, except for purely private purposes, is prohibited except with the prior approval of Solarpraxis AG. This shall apply in particular to reproduction/copies, translations, microfilming and storage in electronic systems. The citing of text by media representatives and political decision-makers is expressly desired and does not require prior approval, provided that the source of any text used is also cited. The texts and illustrations in this brochure were produced with the greatest possible care and to the best of the author’s knowledge. As errors cannot be ruled out and both texts and illustrations are subject to change, we draw your attention to the following: Solarpraxis AG gives no guarantee with regard to the timeliness, accuracy, completeness or quality of the information provided in this brochure. Solarpraxis AG accepts no liability for damages, material or non-material, which are incurred through the use or non-use of the information provided or which are caused directly or indirectly by the use of erroneous and incomplete information, except where deliberate or grossly negligent culpability may be proven. Company entries are the sole responsibility of the respective company.
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Picture credits
“The Industry” sources
COVER
DGS Landesverband Berlin-Brandenburg: Leitfaden Photovoltaische Anlagen, 4th edition, Berlin 2010
See inside front cover INDUSTRY
See captions Unless otherwise stated: Tom Baerwald COMPANIES, PUBLISHERS
The illustrations were supplied by the company/association under whose heading they are published, unless otherwise stated.
Infographics and tables:
Solarpraxis AG, © unless otherwise stated
Konrad Mertens: Photovoltaik, Carl Hanser Verlag, 1st edition, Munich 2011 photovoltaik. Das Magazin für Profis, 01, 04, 05, 06, 07, 08, 10/2012 Volker Quaschning: Regenerative Energiesysteme, Carl Hanser Verlag, 5th edition, Munich
Legal Information Published by
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Idea and concept
Solarpraxis AG Project management/Editor “The Industry”
Solarpraxis AG/Dr Roland Ernst Editor “Companies”
Solarpraxis AG/Ute Bartels Editorial assistance
Katharina Malchow, Sandra Steinmetz
“The Industry” authors
Dr Detlef Koenemann, except
p. 27 (“A view on the United States”) – 29:
Ucilia Wang
Ch. 10 (“Market Situation and Forecasts”):
Ash Sharma, Glenn Gu, Sam Wilkinson, Henning Wicht (iSuppli) “The Industry” technical proofreading
Christian Dürschner
“The Industry” translation
Übersetzungsbüro Peschel Layout & composition
Sunbeam GmbH/derMarkstein.de Photo editor & image processing
Tom Baerwald Infographics
Sunbeam GmbH/Kay Neubert derMarkstein.de Website design by
Sunbeam GmbH Printed by
Druckhaus Berlin-Mitte GmbH
Booklet website
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Your gateway to the solar sector PV Module and PV Power Plant Workshop – China 2013
PV System Technology Forum – EU 2014
Shanghai, China | September 2013
February 2014
Quality for Photovoltaics 2013
PV Power Plants – EU 2014
Berlin, Germany | 12 September 2013
March 2014
Solar meets Glass
PV Project Implementation Conference – China 2014
Dusseldorf, Germany | 09 – 10 October 2013
PV Power Plants – USA 2013 California, USA | November 2013
Solar Industry Summit – Middle East 2013 Dubai, United Arab Emirates | 06 November 2013
14th Forum Solarpraxis Berlin, Germany | 21 – 22 November 2013
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Thin-Film Industry Forum 2014 Berlin, Germany | April 2014
Energy Storage – International Summit for the Storage of Renewable Energies Dusseldorf, Germany | 01 – 02 April 2014
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Solar Solutions from Trusted Experts IHS Solar solutions combines the products, services, and expertise from the IHS acquisitions of three leading research companies and provides forecasts for market demand, technology, and supply chain analysis to advance clients’ strategies in global solar markets.
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Bankability of PV Projects Environmental impact studies (eg. glint and glare reports) Grid connection consulting Yield assessment reports Quality assurance reports Our independent third party reports are accepted by all major European banks. For further information please contact Mr. Christian Steinberg, +49 (0) 30-726296-342,
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Markets & Trends
Photo: A123 Systems
Photo: Solyndra
Photo: Michael Urban
07 | 2012 | 78538
Saudi Arabia: Big plans in store. But, solar players await details before making decisions. Page 28
Industry & Suppliers
Thin film: Erosion of competitive advantage. Thin film makers seek ways to stay afloat. Page 62
photovolta ic
markets
Storage & Smart Grids
Lithium: As storage demand grows, bottlenecks in this raw material’s supply look imminent. Page 92
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Why waste this space?
Photo: HDR, Inc.
Photovoltaic potential on landfills. Page 74
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The World´s Largest Exhibition for the Solar Industry Messe München, Germany Intersolar Europe gives you an insider advantage on cutting-edge information about the dynamic markets of the solar industry Connect with 1,500 international exhibitors Learn everything about the latest innovations Keep up with future trends for continued business success Get inspired!
Cover images Front Main image Vented stationary lead-acid battery with a liquid electrolyte. The tubular plates technology is designed to result in a large number of cycles during the batteries’ lifetime. (Photo: Tom Baerwald/HOPPECKE Batterien GmbH & Co. KG) Small images, f.l.t.r. Taking measurements using a thermal imaging camera (Photo: Tom Baerwald/Lebherz) Central inverter in a ground-mounted installation (Photo: Tom Baerwald) String inverter in an electromagnetic compatibility (EMC) test chamber (Photo: SMA Solar Technology AG) Back Climate chamber test to ensure that inverters withstand extreme temperature variations (Photo: SMA Solar Technology AG)
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Inverter, Storage and PV System Technology
“Inverter, Storage and PV System Technology” takes a close look at the electrical components of the PV system and its interactions, presents the latest technical developments, and gives an overview of market conditions.
Inverter, Storage and PV System Technology
Corporate portraits of international companies round off this comprehensive industry guide on PV system technology. www.pv-system-tech.com
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