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English. 0920-30102-002 Release Date: 2011-04-01 Visit http://www.solyndra.com for the mostcurrent version of this document.
Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
GENERAL DISCLAIMER The information contained in Solyndra’s instructions, guides, application notes, or any other document is advisory in nature only. Solyndra makes no representation or warranties that any referenced techniques or methods are necessarily safe, legal, or compliant with applicable codes and regulations. The customer must work with qualified system designers, installers and other professional personnel as required to ensure that all Solyndra photovoltaic system designs and installations are safe and in compliance with all applicable codes and regulations. Solyndra assumes no legal liability or responsibility for the accuracy, completeness, or usefulness of any information or processes disclosed herein. Reference herein to any particular commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by Solyndra.
WARRANTY DISCLAIMER The warranty terms for Solyndra’s photovoltaic products are governed solely by the express terms of the Solyndra Limited Warranty provided to the purchaser of Solyndra products as may be transferred there under. Solyndra expressly disclaims any and all other express warranties and any and all implied warranties, including but not limited to those relating to the sale and/or use of Solyndra photovoltaic products, fitness for a particular purpose, merchantability or non-infringement or infringement of any intellectual property right. Solyndra may make changes to specifications, guidelines, and products at any time without notice. Purchasers or potential purchasers, designers and installers should contact their local Solyndra representative or the Solyndra website to ensure that they have and are working with the most up-to-date information and documentation relating to Solyndra’s photovoltaic products.
Trademarks /Patents/Copyright Notice [All Guides] The following terms are trademarks or service marks of Solyndra LLC: Solyndra; The New Shape of Solar. All other trademarks and registered trademarks are the property of their respective companies. Solyndra products are covered by patents in the US and many other countries. Copyright (circle logo ©) Solyndra LLC 2011. Printed in the United States of America. All Rights Reserved. UB.EN.20110319.V1-0.
Contact Information Headquarters
Regional Support Contacts
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US & Canada
877-511-8436
English
[email protected]
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353 61 79 1124
DE, EN, FR, IT
[email protected]
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0800 50735
English
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France
0800 942896
French, English
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Germany
0800 0004366
German, English
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00800 3973 4547 English
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800 125604
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900 800566
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UK
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Solyndra International AG Lindenstrasse 16 6340 Baar, Switzerland
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Design Guide 200 Series
Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
Contents Chapter 1 Designing with Solyndra Panels
4
1.1. Code Compliance & Safety................................................................................................................................................4 1.2. Required Information.......................................................................................................................................................4 1.3. Design Sequence...............................................................................................................................................................4
Chapter 2 Wiring
5
2.1. The Solyndra Connector System......................................................................................................................................5 2.2. String Blocks......................................................................................................................................................................7 2.3. String Wiring......................................................................................................................................................................8 2.4. Home Run Wiring..............................................................................................................................................................9 2.5. Grounding........................................................................................................................................................................ 10 2.6. Array Installation around Lightning Grids ..................................................................................................................... 10
Chapter 3 Planning the Panel Layout
11
3.1. Designing for Wind...........................................................................................................................................................11 3.2. Roof Zone Definitions......................................................................................................................................................12 3.3. Placing Panels Over Roof Objects.................................................................................................................................. 16 3.4. Planning Layouts for Uneven Roofs............................................................................................................................... 16 3.5. Estimating Energy Yield.................................................................................................................................................. 16
Chapter 4 Design in Seismic Areas
17
4.1. Clearance Tables for Building Site Zones B, C, D............................................................................................................ 19 4.2. Clearance Tables for Building Site Zone E......................................................................................................................20 4.3. A Note on Code Compliance .......................................................................................................................................... 22
Chapter 5 Solyndra Panel System
23
5.1. Solyndra Panels & Mounts..............................................................................................................................................23 5.2. Solyndra Cable Management System............................................................................................................................24 5.3. Optional Panel Mounting Components.........................................................................................................................24 5.4. Standard Configuration...................................................................................................................................................25 5.5. Roof Loads.......................................................................................................................................................................26
Chapter 6 Optimum Inverter Selection
29
6.1. Inverter Sizing.................................................................................................................................................................29 6.2. Summary..........................................................................................................................................................................30
Chapter 7 Solyndra CAD Toolkit
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Solyndra Confidential
Design Guide 200 Series 3
Designing with Solyndra Panels
Chapter 1 Designing with Solyndra Panels The purpose of this document is to provide design information for Solyndra 200 Series photovoltaic systems. The target audience is system designers and engineers who are already skilled in photovoltaic system design. This guide will highlight the unique properties of the Solyndra 200 Series technology and their impact on system design, but is not intended to cover all aspects of system design. Solyndra panels are designed to deliver optimum performance when installed over white, high reflectance roofs. Projects that do not follow Solyndra’s design and installation guidelines may not provide the expected energy yield, and will not be covered by Solyndra’s warranty.
1.1. Code Compliance & Safety System installations should be designed by a properly-licensed professional in accordance with all applicable codes and standards. Solyndra panels are made of glass and can be broken. Hazardous voltage is present in photovoltaic cells at all times when they are exposed to any light source. Before handling Solyndra panels, all Solyndra procedure, safety recommendations, and all local safety requirements applicable for working on roofs and around electrical equipment must be read and understood by all personnel. Reference to the Solyndra Installation Guide may be made for safety recommendations.
1.2. Required Information In order for an effective design to be produced, the designer needs information about the installation site. For a preliminary design, items which are required are as follow: • Address of site. • Roof diagram with dimensions, including height, and contour if available. • Roofing material type. • Roof slope. • Roof deck and load bearing capacity. • Height of nearby structures, if any. • Design wind speed, snow-load, and hail exposure. • Seismic requirements, if any. • Locations and dimensions of all roof obstructions. • Orientation of building. • Shading analysis.
1.3. Design Sequence Design begins with the determination of string length using Solyndra’s Inverter and String Sizing Tool (see “2.3. String Wiring” on page 8), or other calculation methods, to achieve proper voltage match for an inverter type. Next, a rooftop layout is prepared. This will allow the most accurate determination of panel count, at which stage an energy yield forecast can be prepared. The final step is the preparation of a complete Bill of Materials for purchase, and an installation plan, including roof loading (structural) design.
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Design Guide 200 Series
Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
Wiring
Chapter 2 Wiring 2.1. The Solyndra Connector System Each Solyndra panel has four connectors; two for positive and two for negative. The connectors are arranged to make it possible to implement series and parallel connections between panels in an array. The panel and its connectors are shown in Figure 1, along with the CAD tool symbol from the CAD package that Solyndra offers. Refer to Chapter 7 on page 31 for detail of the CAD tool package.
Figure 1. Solyndra PV Panel and Power Connections + Positive Side
Male +
Female + – Negative Side Male -
Female -
Female + Male -
Female -
Male -
The preferred orientation for Solyndra panels is with the modules (tubes) oriented north-south. Panels are then wired in series, as shown in Figure 2. This type of connection is commonly referred to as a string.
Figure 2. Two Panels Wired in Series + Positive Side
Male +
Female + – Negative Side
Female – Male +
+ Positive Side
Male – Female +
Male -
Female +
– Negative Side
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Wiring
Horizontal string connections are also possible, as shown in Figure 3. It is important when connecting panels in horizontal strings, as shown in Figure 3, that only connector pair be connected. Connecting both pairs would create a short circuit between the two panels.
Figure 3. Series Connection, End-to-End Panels Do not connect! + Positive Side
Female, +
Male + – Negative Side
– Negative Side Male, –
Male, Female, + –
Female + Positive Side
Female +
Male +
Correct four-panel strings are shown in Figure 4. Notice how positive connectors are connected to negative connectors starting at the tail end of the string arrow (in green) and going towards the head of the arrow, increasing the total voltage with each panel.
Figure 4. Four-Panel Series Connections
Figure 5 shows connections between panels in a typical view from underneath the array.
Figure 5. Interpanel Connection of Positive and Negative Pigtails
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Design Guide 200 Series
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A string is a group of panels whose electrical connections are in series. The number of panels needed in each string depends on the inverter chosen. Strings can be connected in parallel within an array to reduce home run wiring costs. A typical 4 by 4 array is shown in Figure 6. Note the parallel connections, indicated by the red jumper symbols at the top of the array, and the blue jumper symbols at the bottom of the array.
Figure 6. A 4 by 4 String Block Home Run Connection
Home Run Connection
Some designs use strings six panels long. An example is shown in Figure 7. Note that in Figure 6 and Figure 7 all series and parallel connections can be made using only the built-in panel connectors.
Figure 7. A 6 by 4 String Block Home Run Connection
Home Run Connection
In some cases, the standard string-block arrangement may not be convenient for a roof location due to obstacles or other factors. Figure 8 shows a 24-panel horizontal string block. In this design, short jumper cables (shown in red and blue) will be required to make the parallel connections on the positive and negative ends of the string block. Note that the string blocks shown in Figure 7 and Figure 8, while physically different, are electrically equivalent.
Figure 8. A 4 by 6 String Block
Home Run Connection 0920-30102-002
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Positive Jumpers
Home Run Connection
Design Guide 200 Series 7
Wiring
2.2. String Blocks
Wiring
2.3. String Wiring An inverter and string sizing tool is offered by Solyndra to assist in determining the optimum string length and the correct inverter size for the array. The tool is available in two versions, one for North American systems (up to 600V) and one for EU systems (up to 1000V). These tools are Excel spreadsheets named Inverter_and_StringSizing-200Series-EU and Inverter_and_StringSizing-200Series-NA. These tools may be obtained from Solyndra or an authorized distributor.
2.3.1. Determining String Length The number of panels placed in series determines the system voltage. The system voltage must stay below the smallest of: • the maximum voltage rating of the inverter • the rated working voltage of the wiring • all applicable electrical codes In the US, electrical equipment and wiring is rated for 600 volts maximum; in Europe the maximum rating can be as high as 1000 volts. Because panel voltage varies with temperature, the maximum voltage occurs when the temperature is cold and the inverter is off. Similarly, array voltage should be designed to stay above the minimum inverter tracking voltage when the temperature is hot and the array is operating at its maximum power point voltage, Vmp. Refer to the panel data sheet for specific temperature coefficients.
2.3.2. Parallel Strings Connecting strings in parallel within the array reduces the amount of home-run wiring needed, saving time and cost. First, the series fuse size for each string block must be determined. The equation is: Eqn 1. I fuse = 1.56 (N : I sc) Where N is the number of strings to be connected in parallel and Isc is taken from the panel data sheet. The calculated value must be rounded up to the next larger size. Values are listed in Table 1.
Table 1.
Ifuse, Minimum Series Fuse Size for Multiple Strings in Parallel
Panel Power Rating
182
191
200
210
220
I5
2.33
2.34
2.35
2.36
2.37
Amps
4
4
4
4
4
Amps
One String
Watts
Two Strings
8
8
8
8
8
Amps
Three Strings
11
11
11
11
11
Amps
Four Strings
15
15
15
15
15
Amps
2.3.3. Maximum Number of Parallel Strings The maximum number of strings which can be wired in parallel is limited by the series fuse rating of the panel. In order to determine the number of strings, the Fault Current Equation as specified by the controlling code authority must be used. As an example, the IEC Fault Current Equation is shown in Eqn 2: Eqn 2.
I fault = I fuse + 1.25 ^N - 1 h I sc
where N is the number of strings to be connected in parallel while still keeping the maximum fault current (Ifault) less than the series fuse rating, as specified in the data sheet. This can be solved for N, the number of strings, as: Eqn 3. N = ( I fault - I fuse ) + 1
1.25I sc
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Design Guide 200 Series
Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
Table 2.
Maximum Number of Parallel Strings per Fused Home Run
Panel Power Rating
182
191
200
210
220
Watts
Isc
2.33
2.34
2.35
2.36
2.37
Amps
N, calculated
4.17
4.16
4.14
4.13
4.11
strings
4
4
4
4
4
strings
N, rounded down
2.4. Home Run Wiring Home run wires from string blocks are connected in parallel inside combiner boxes. Just as each panel has four connections, each of the four corners of a string block will have a positive or negative pigtail available. Run a positive home run cable and a negative home run cable from the corners in a way that minimizes cable length. Use the Solyndra Cable Management System to keep wires organized and prevent them from dangling. It is shown in Figure 9, and it includes long and short channels, hangers and pegs, and panelmount cable channels.
Figure 9. Cable Management System and Close-up View of Corner
The Solyndra cable management system makes it easy to efficiently route home run wiring. An example for 4 by 4 systems is shown in Figure 10; one for 6 by 4 systems is shown in Figure 11.
Figure 10. Typical Home Run Wiring - 4 by 4 String Blocks
4x4 string block Standard 8 x 12 (96 panels) equals 6 4x4 blocks
Double-wide (192 panels) equals 12 4x4 blocks
Home run wiring
Figure 11. Typical Home Run Wiring - 6 by 4 String Blocks
4x6 string block Standard 8 x 12 (96 panels) equals 4 4x6 blocks
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Home run wiring
Design Guide 200 Series 9
Wiring
The series fuse rating for 200 Series Panels is 24.4 Amps. Substituting this into Eqn 3 this for the fault current, and using the short-circuit current rating as specified in the data sheet, the maximum number of strings can be calculated. The results are shown in Table 2. It is permissible to have string blocks of fewer than the maximum number of strings in parallel.
Wiring
2.5. Grounding Solyndra 200 Series Panels and mounts meet the requirements for IEC Protection Class II . It is not necessary to ground the array, or to ground any particular lead of the array at the inverter (unless required by code) when installing a Solyndra system. Due to the hermetic seals used in the construction of each Solyndra module, they are not susceptible to corrosion damage from voltage offsets with respect to ground.
2.6. Array Installation around Lightning Grids Some rooftops are fitted with a lightning grid. A lightning grid is an array of wires running horizontally in both directions across a roof. Dimensions vary, but typically the wires are spaced a few meters apart, and the entire grid is carefully grounded to earth. These grids are occasionally fitted with vertical conductors called air terminals, or ‘lightning rods’. A Solyndra system, when installed, may be placed over a lightning grid. Certain guidelines must be followed, but Solyndra panels do not impact the function of lightning systems or make the building more likely to have a lightning event.
Array Placement Guidelines with Lightning Grids 1. Engineering for a photovoltaic system on roofs with lightning grids requires obtaining the S dimension required by code, either from the original designer or by re-calculating it. The S dimension is the minimum separation distance from the lightning grid required if additional precautions are not taken. 2. If panels are to be installed within distance S of the lightning grid components there are certain applicable electrical code requirements. These may include a requirement to connect exposed metal components to the lightning grid and a recommendation that conductors coming into the building be protected by voltage shunt devices. 3. Solyndra 200 Series Panels and mounts are IEC certified Class II devices. They are not considered to have exposed metal parts and therefore do not have a requirement to be attached to the lightning grid, even if placed within the S distance. 4. Because Solyndra 200 Series Panels are IEC certified Class II devices, voltage shunt devices are not required, but are recommended, for building lead-ins and inverter protection. Use of such devices is a design decision that should be based on sensitivity of building use, or an inverter protection risk versus cost analysis. 5. Solyndra panels should never be placed over air terminals. Any air terminals that are under the array must be moved. 6. Modifying the lightning protection system to protect the Solyndra array is not necessary.
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Design Guide 200 Series
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This chapter explains the rules for placing Solyndra 200 Series panels on a building roof. Solyndra panels are designed to be installed flat, elevated above the roof surface by Solyndra panel mounts. The open design of the Solyndra panel reduces wind effects, so they are self-ballasted against sliding and uplift. By attaching groups of panels together, mass is increased such that panel movement does not occur. A properly-assembled array has sufficient mass to resist movement without the need for attachment to the roof. In order to insure that high winds do not lift the panels, certain minimum clearances from building edges and other structures must be maintained. Panels shall only be placed over firmly-attached roof surfaces. Loose-laid membranes or other materials are not acceptable. As with any rooftop solar system, the design must also meet fire, safety, and access clearance requirements, as dictated by applicable codes.
3.1. Designing for Wind The Solyndra panel-and-mount system, when installed according to Solyndra guidelines, has been certified at wind speeds up to 130 MPH (208 KPH) in wind tunnel and outdoor studies. Wind speeds are defined as a 3-second gust measured at 10 meters, per ASCE 7-05, Figure 6.1. Wind speed-up due to local topography must be considered when establishing design wind speed. Consult ASCE 7-05, Section 6.5.7. Tornadoes have not been considered in developing this specification.
3.1.1. Physical Sub-Array Definition For purposes of wind analysis, the term sub-array is defined as a group of panels which are physically connected together. The manner of electrical connection(s) is not relevant to this definition. The larger the sub-array, the greater the physical stability of the system.
3.1.2. Coefficients of Friction Friction between the Panel Mount and the roof makes the panels resist movement. Solyndra has tested various combinations of Panel Mount materials and roof materials. The results are shown in Table 3. Pads are available from Solyndra. The designer is responsible for ensuring that proper friction assumptions are used.
Table 3.
Coefficients of Static Friction (Fc) for Common Roofing Materials
Roof material
Panel Mount (bare) Panel Mount with EPDM pad
Panel Mount with PVC pad
Not recommended Not recommended
Panel Mount with TPO pad 1.2
TPO membrane
0.8
Elastomeric coatings
1.2
1.2
EVA membrane
1.6
Not recommended
1.4
Not recommended
PVC membrane
1.0
Not recommended
0.8
Not recommended
EPDM membrane
1.0
1.0
Hard coatings
0.6
Not recommended Not recommended
Not recommended Not recommended
Not recommended Not recommended
0.8
‘Not recommended’ means that the combination is not chemically compatible. Care should be taken during installation on icy or dirty surfaces as these can reduce friction below measured values.
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Design Guide 200 Series 11
Planning the Panel Layout
Chapter 3 Planning the Panel Layout
Planning the Panel Layout
3.2. Roof Zone Definitions Wind clearance rules are defined according to corner, edge, and middle zones of the roof. Following the approach of ASCE 7-05, four roof zones have been defined: • The minimum setback zone, a strip 5 feet (1.52 m) wide all around the rooftop perimeter. Panels are never permitted here. This zone is based on extensive wind testing and analysis. • Zone A, a strip adjacent to the setback zone. Panels may be placed here, with conditions. • Zone B, an arc segment at each roof corner. Panels may be placed here, with conditions. • Zone C, the portion not included in A or B. Panels may be placed here, with conditions.
Slopes and Parapets Roof zone definitions depend on both roof slope and the height of the parapet wall, if any. Roof slopes can be less than 1:10 (5.7°), or up to 2:12 (9.6°). Solyndra panels using Solyndra-supplied mounts are not permitted on roof slopes greater than 2:12 (9.6°).
Zone A Zone A is defined as the area of the roof between the 5-foot (1.52 m) setback line and the line defined by Dimension A. Dimension A is defined as including the 5-foot (1.52 m) setback. This means that if the calculation gives a value of 5 feet (1.52 m), there is no Zone A. In other words, for rectangular buildings less that 12.5 feet (3.8 m) high, or less than 50 feet (15.2 m) wide, the 5-foot (1.52 m) setback is sufficient, and the width of Zone A is effectively zero, that is, there is no Zone A.
Determining Dimension A
Step 1: Calculate two values:
• 40% of the building height. • 10% of the lesser of building length or width.
Step 2: Select the smallest of these possible dimensions.
Step 3: Compare the result with 5 feet (1.52 m). Dimension A is the largest of these values.
Zone B Zone B is the intersection of a the pie-shaped section at each exterior corner and Zone A. The pie-section is defined by Dimension B, which is a radius, from the corner of the building, equal to 100% of the building height. The shape of Zone B is different for high and low parapet roofs. For high-parapet roofs, the intersection of Zone A and Zone B is defined as Zone B. For low-parapet roofs, the intersection of Zone A and Zone B is a forbidden area.
Definition of Building Dimensions Building height is defined as the height above ground of the portion of the roof on which the array is installed. For rectangular buildings, the definitions of length, width, and height are clear. If the building is non-rectangular, consult ASCE 7-05 for definitions. Height is defined as the height, above the surrounding terrain or ground, of the portion of the roof on which the array is installed. There should be no surrounding buildings taller than 150% of roof height within a distance equal to 200% of roof height. The rules cited herein should be considered minimums. When more panels are connected together in an array, the array has more resistance to wind effects. Whenever possible, build arrays larger than the minimum. If a small array is being erected for evaluation purposes, place it in the center of the roof; well away from Zone A and Zone B.
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Design Guide 200 Series
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Zone definitions depend on roof slope, parapet height, and whether there is a roof ridge. Zone definition drawings are shown in Table 4. A high parapet is one that is 19” (48 cm) or more in height. For slopes less than 1:10, no distinction is made between monoslope and ridged.
Table 4. Zone Definition Drawing Key Roof Slope Less than 1:10 (5.7°)
Monoslope or Ridged
Between 1:10 and 2:12 (5.7°-9.6°)
Monoslope
Between 1:10 and 2:12 (5.7°-9.6°)
Ridged
High Parapet
Low Parapet
Figure 12
Figure 13
Figure 14
Figure 15
In each of the figures, red represents roof area in which panels may never be placed.
Figure 12. Roof Zone Definition - High Parapet; Monoslope ≤ 2:12; Ridged ≤ 1:10 5 ft (1.52 m) edge setback Zone A Zone B Zone B
Building Wall 5 ft (1.52 m) edge setback Zone A
Zone B Zone A 5 ft (1.52 m) edge setback
5 ft (1.52 m) edge setback Zone A
Dimension A
Dimension B
Zone C
Zone B
Zone B
Zone B Zone A 5 ft (1.52 m) edge setback
Figure 13. Roof Zone Definition - Low Parapet; Monoslope ≤ 2:12; Ridged ≤ 1:10 5 ft (1.52 m) edge setback Zone A Zone B Zone B
5 ft (1.52 m) edge setback Zone A
Dimension A
Building Wall 5 ft (1.52 m) edge setback Zone A
Zone C
Zone A 5 ft (1.52 m) edge setback
Zone B
Dimension B
Zone B
Zone B
Zone B Zone A 5 ft (1.52 m) edge setback
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Planning the Panel Layout
3.2.1. Roof Zone Defintions
5 ft (1.52 m) edge setback Zone A
Zone B
Roof Ridge
Dimension B Zone A
Zone A
Zone A
Zone C
Dimension A
Dimension A’ (*)
Zone B
Zone B
Zone A
Zone B
Dimension B
Zone C
Zone B
Zone A
Zone B
Zone B
Zone A
Planning the Panel Layout
Figure 14. Ridged Roof, Slope ≤2:12, High Parapet
Zone B
Zone A
Figure 15. Ridged Roof, Slope ≤2:12, Low Parapet 5 ft (1.52 m) edge setback
Roof Ridge
Zone A
Zone A Zone B
Dimension B
Dimension B Zone C
Zone A
Zone A
Zone A
Zone C
Dimension A
Dimension A’ (*) Zone B
Zone B Zone A
Zone B
Zone B
Zone A
Zone B
Zone B
Zone B Zone A
* Dimension A’ does not require the minimum 5-foot (1.52 m) setback.
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Design Guide 200 Series
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Table 5 defines the minimum sub-array sizes for roofs up to 60 feet (18.3 m) high, with slope less than 1:10. Table 6 defines the minimum sub-array sizes for roofs up to 60 feet (18.3 m) high, with slope less than 2:12.
Table 5.
Minimum Sub-Array Sizes: Buildings ≤ 60 Ft (18.3 m) High, ≤1:10 Slope
Fc (1)
Wind 85 mph 90 mph 95 mph 100 mph 105 mph 110 mph 115 mph 120 mph 125 mph 130 mph Speed 137 kph 145 kph 153 kph 161 kph 169 kph 177 kph 185 kph 193 kph 201 kph 208 kph Roof Zone
≥0.6
≥0.8
≥1.0
A (2, 3)
4
4
9
9
16
25
25
36
49
100
B, low (4)
4
9
16
36
64
100
NA
NA
NA
NA
B, high (4)
4
4
9
4
9
16
36
49
81
NA
C
4
4
9
9
9
16
25
25
36
49
A (2, 3)
4
4
4
4
9
9
9
16
25
25
B, low (4)
4
4
4
4
4
16
25
36
49
64
B, high (4)
4
4
4
4
4
9
9
16
16
25
C
4
4
4
4
9
9
9
16
16
25
A (2, 3)
4
4
4
4
4
9
9
9
9
16
B, low (4)
4
4
4
4
4
9
9
9
9
25
B, high (4)
4
4
4
4
4
9
9
9
9
16
C
1
1
4
4
4
9
9
9
9
16
Table 6. Minimum Sub-Array Sizes: Buildings ≤ 60 Ft (18.3 m) High, ≤2:12 Slope Fc (1)
Wind Speed
85 mph 137 kph
95 mph 153 kph
130 mph 208 kph
Roof Zone
≥0.6
≥0.8
≥1.0
A (2, 3)
54
63
NA
B, low (4)
40
63
NA
B, high (4)
40
60
108
C
18
32
98
A (2, 3)
12
20
45
B, low (4)
8
8
60
B, high (4)
12
27
44
C
9
12
40
A (2, 3)
8
8
40
B, low (4)
8
8
40
B, high (4)
8
8
15
C
8
8
24
Figure 16. Notes for Table 5 and Table 6. 1. Fc is the coefficient of friction, from Table 3. 2. The array must be as deep, or deeper, than it is wide, that is, the number of panels in direction towards center of roof must equal or exceed number of panels along perimeter (see drawing at right). 3. No array can be fully inside Zone A. An array shall have at least two times as many panels in Zone C as in Zone A (see drawing at right. 4. Zone B is defined by Figure 12, Figure 13, Figure 14, or Figure 15, based on low or high parapet. 5. NA is Not Allowed.
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Building Wall Zone A
5 ft (1.52 m) edge setback
Zone C Not Acceptable
Not Acceptable
Acceptable
Design Guide 200 Series 15
Planning the Panel Layout
3.2.2. Minimum Sub-Array Sizes
Planning the Panel Layout
3.3. Placing Panels Over Roof Objects • Never place panels over objects more than 10 inches (25 cm) tall, or elevate panels to clear objects. • Any building steps or obstructions more than 10 inches (25 cm) high, such as overruns, HVAC units or skylights, shall have a minimum clearance equal to the lesser of the obstruction’s width or twice its height.
3.4. Planning Layouts for Uneven Roofs Panel Mounts should not be placed wholly or partially on raised areas such that the surface contact area between the mount and roof is reduced, or such that there is a large height disparity between panels. For stability, it is recommended that the mounts not be placed on the peaks of a non-flat patterned roofs. It is also recommended that the roof structure’s load-bearing capability be assessed wherever the mounts are placed. Many roofs have local ridges and valleys for drainage. Layouts should be designed such that Panel Mounts rest solidly on the roof. Figure 17 shows several placements. When peaks and valleys are present, as in (b), do not place mounts on peaks. This places excess localized pressure on the roof. Avoid valleys if possible, as the mount can affect drainage.
Figure 17. Right and Wrong Ways to Place Panels on Uneven Roofs
Acceptable
Acceptable (a)
Unacceptable
Avoid if possible
Unacceptable (b)
Angles at Panel Joints 200 Series Panel Mounts form flexible joints, and can generally be placed on any roof surface that varies less than 10 degrees from surface to surface. Under certain circumstances it may be possible to bridge differences of roof slope up to 18 degrees provided that the following rules are adhered to: • Panels can bridge either parallel or perpendicular to a ridge or valley, but the center axis of the panel must be within 10 inches (25 cm) of the ridge peak. • Panels which use Snow Mounts cannot bridge perpendicularly across a ridge or valley because this may interfere with Snow Mount locations, unless additional Snow Mounts are used. • While it is possible to bridge valleys, accessibility and local requirements to keep drainages clear may recommend against this design.
3.5. Estimating Energy Yield When the layout is completed, Solyndra’s on-line energy yield forecast tool can be used to estimate hourly, daily, monthly, and annual energy yield. Detailed results are available on-screen, in a downloadable report, and in a downloadable Excel spreadsheet. For instructions in the use of this tool, refer to the Energy Yield Forecast Tool User Guide. Contact a Solyndra representative to obtain access to the tool.
16
Design Guide 200 Series
Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
A Solyndra array, properly installed on a rooftop, functions as a seismically-isolated system. It is designed to have some movement in the largest seismic events. When designing systems for seismically-active areas, clearances must be maintained around the array to allow for maximum possible displacements in a worstcase seismic event. In order to determine the amount of clearance required, the engineer must determine the parameters listed below. Solyndra recommends that designers work with a qualified seismic engineer who is familiar with seismic conditions in the region where the array will be installed, and can determine the building period of the structure where the array will be installed.
Understanding Seismic Hazard Levels This chapter uses a method to determine expected earthquake-induced array displacements for locations with a varying intensity of seismic hazard. The seismic hazard at a given location can be defined by two parameters: the short period Maximum Considered Earthquake (MCE*) spectral response acceleration (SS), and the 1-second MCE spectral response acceleration (S1). The levels of seismic hazard are defined by maximum spectral response acceleration parameters. Four levels are defined: Low (Level 1), Moderate (Level 2), High (Level 3), and Very High (Level 4) seismic activity. Any site with spectral response parameters equal to or lower than the maximum values for a seismic hazard level are within that level. The expected seismically-induced array displacements for any Solyndra installation can be determined from the seismic hazard level of the site. The spectral response parameters that define the four seismic hazard levels are shown in Table 7.
Table 7.
Seismic Level Spectral Parameters
Seismic Hazard Level
Seismic Hazard Description
Maximum SS
Maximum S1
Units
1
Low
0.533
0.210
G
2
Medium
1.500
0.600
G
3
High
2.000
0.940
G
4
Very High
2.893
1.237
G
Multiple soil conditions are also considered for each of the four levels in this study by adjusting the SS and S1 values by site soil coefficients (Fa and Fv) per ASCE 7-05. Only site Classes B, C, D, and E (as defined by ASCE 7-05) are considered in this study. Site Class A is not considered as it is rarely encountered in occupied areas. The adjusted values are then used to define the MCE response spectra for each soil type considered.
* The MCE is defined as an earthquake of such intensity that there is a 2% probability that it would be exceeded in a time period of 50 years (or equivalently with a return period of 2,475 years). 0920-30102-002
Solyndra Confidential
Design Guide 200 Series 17
Design in Seismic Areas
Chapter 4 Design in Seismic Areas
Design in Seismic Areas
Roof Slope. Arrays should not be installed on roofs with slopes greater than 1:12 (4.76 degrees) in seismically-active areas
Coefficient of Friction For seismic purposes, the coefficient of friction is the dynamic friction between the roof surface and the chosen panel mount. Refer to Table 8 for values.
Table 8. Dynamic Coefficients of Friction for Common Roofing Materials Roof material
Panel Mount (bare) Panel Mount with EPDM pad
Panel Mount with PVC pad
Panel Mount with TPO pad 0.8
TPO membrane
0.6
1.0
Not recommended
Elastomeric coatings
0.6
1.0
Not recommended Not recommended
EVA membrane
0.8
Not recommended
PVC membrane
0.6
Not recommended Not recommended
EPDM membrane
1.0
0.8
Not recommended Not recommended
Not recommended
0.6
Not recommended Not recommended
Hard coatings
1.0
Not recommended 0.6
‘Not recommended’ means that the combination is not chemically compatible. Care should be taken during installation on icy or dirty surfaces as these can reduce friction below measured values.
Wiring Combiner boxes must be set back from the array a distance greater that the specified displacement. Homerun wiring must be flexible and include strain-reliefs. It must be long enough not to restrict any possible movement of the panels in a seismic event.
18
Design Guide 200 Series
Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
Table 9. Clearance for Coefficient of Friction ≥ 0.6; Site Classes B, C, D Seismic Hazard Level
1
Building Period 0.1 0.2 0.3 0.4 0.5
Clearance, 1/4:12 slope inches cm 1 2.5 1 2.5 1 2.5 1 2.5 2 5.1
Clearance, 1/2:12 slope inches cm 1 2.5 1 2.5 1 2.5 2 5.1 2 5.1
Clearance, 1:12 slope inches cm 1 2.5 2 5.1 2 5.1 3 7.6 2 5.1
2
0.1 0.2 0.3 0.4 0.5
3 6 8 12 12
7.6 15.2 20.3 30.5 30.5
4 8 12 15 18
10.2 20.3 30.5 38.1 45.7
7 14 22 25 30
17.8 35.6 55.9 63.5 76.2
3
0.1 0.2 0.3 0.4 0.5
6 7 9 13 15
15.2 17.8 22.9 33 38.1
5 9 13 16 20
12.7 22.9 33 40.6 50.8
7 15 23 17 34
17.8 38.1 58.4 43.2 86.4
4
0.1 0.2 0.3 0.4 0.5
10 13 16 21 26
25.4 33 40.6 53.3 66
10 16 22 27 36
25.4 40.6 55.9 68.6 91.4
15 38.1 27 68.6 Not Recommended Not Recommended Not Recommended
Table 10. Clearance for Coefficient of Friction ≥ 0.8; Site Classes B, C, D Seismic Hazard Level
1
0920-30102-002
Building Period 0.1 0.2 0.3 0.4 0.5
Clearance, 1/4:12 slope inches cm 1 2.5 1 2.5 1 2.5 1 2.5 1 2.5
Clearance, 1/2:12 slope inches cm 1 2.5 1 2.5 1 2.5 1 2.5 1 2.5
Clearance, 1:12 slope inches cm 1 2.5 1 2.5 1 2.5 2 5.1 1 2.5
2
0.1 0.2 0.3 0.4 0.5
2 4 6 10 10
5.1 10.2 15.2 25.4 25.4
3 6 8 12 14
7.6 15.2 20.8 30.5 35.6
5 9 15 18 23
12.7 22.9 38.1 45.7 58.4
3
0.1 0.2 0.3 0.4 0.5
3 6 9 11 12
7.6 15.2 22.9 27.9 30.5
4 7 10 13 15
10.2 17.8 25.4 33 38.1
4 10 17 20 25
10.2 25.4 43.2 50.8 63.5
4
0.1 0.2 0.3 0.4 0.5
8 11 14 19 22
20.3 27.9 35.6 48.3 55.9
8 13 17 23 30
20.3 33 43.2 58.4 76.2
Solyndra Confidential
9 22.9 20 50.8 31 78.7 Not Recommended Not Recommended
Design Guide 200 Series 19
Design in Seismic Areas
4.1. Clearance Tables for Building Site Zones B, C, D
Design in Seismic Areas
Table 11. Clearance for Coefficient of Friction ≥ 1.0; Site Classes B, C, D Seismic Hazard Level
1
Building Period 0.1 0.2 0.3 0.4 0.5
Clearance, 1/4:12 slope inches cm 1 2.5 1 2.5 1 2.5 1 2.5 1 2.5
Clearance, 1/2:12 slope inches cm 1 2.5 1 2.5 1 2.5 1 2.5 1 2.5
Clearance, 1:12 slope inches cm 1 2.5 1 2.5 1 2.5 1 2.5 1 2.5
2
0.1 0.2 0.3 0.4 0.5
2 3 5 9 9
5.1 7.6 12.7 22.9 22.9
2 4 7 10 12
5.1 10.2 17.8 25.4 30.5
3 6 11 15 19
7.6 15.2 27.9 38.1 48.3
3
0.1 0.2 0.3 0.4 0.5
3 5 7 10 10
7.6 12.7 17.8 25.4 25.4
3 6 8 11 12
7.6 15.2 20.3 27.9 30.5
3 8 13 16 19
7.6 20.3 33 40.6 48.3
4
0.1 0.2 0.3 0.4 0.5
6 10 13 16 19
15.2 25.4 33 40.6 48.3
6 11 15 20 24
15.2 27.9 38.1 50.8 61
7 17.8 16 40.6 25 63.5 31 78.7 Not Recommended
4.2. Clearance Tables for Building Site Zone E Table 12. Clearance for Coefficient of Friction ≥ 0.6; Site Class E Seismic Hazard Level
1
20
Building Period 0.1 0.2 0.3 0.4 0.5
Clearance, 1/4:12 slope inches cm 1 2.5 1 2.5 2 5.1 3 7.6 5 12.7
Clearance, 1/2:12 slope inches cm 1 2.5 2 5.1 2 5.1 3 7.6 6 15.2
Clearance, 1:12 slope inches cm 2 5.1 3 7.6 3 7.6 5 12.7 10 25.4
2
0.1 0.2 0.3 0.4 0.5
3 5 6 10 10
7.6 12.7 15.2 25.4 25.4
4 6 10 12 14
10.2 15.2 225 30.5 35.6
6 11 17 20 24
15.2 27.9 43.2 50.8 61
3
0.1 0.2 0.3 0.4 0.5
4 6 8 10 12
10.2 15.2 20.3 25.4 30.5
4 7 10 13 17
10.2 17.8 25.4 33 43.2
6 13 19 23 28
15.2 33 48.3 58.4 71.1
4
0.1 0.2 0.3 0.4 0.5
8 10 13 17 22
20.3 25.4 33 43.2 55.9
8 13 18 23 30
20.3 33 45.7 58.4 76.2
Design Guide 200 Series
12 30.5 22 55.9 33 83.8 Not Recommended Not Recommended
Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
Seismic Hazard Level
1
Building Period 0.1 0.2 0.3 0.4 0.5
Clearance, 1/4:12 slope inches cm 1 2.5 1 2.5 2 5.1 2 5.1 5 12.7
Clearance, 1/2:12 slope inches cm 1 2.5 1 2.5 2 5.1 2 5.1 5 12.7
Clearance, 1:12 slope inches cm 1 2.5 2 5.1 2 5.1 3 7.6 7 17.8
2
0.1 0.2 0.3 0.4 0.5
2 3 5 8 8
5.1 7.6 12.7 20.3 20.3
2 4 7 10 11
5.1 10.2 17.8 25.4 27.9
4 7 11 15 18
10.2 17.8 27.9 38.1 45.7
3
0.1 0.2 0.3 0.4 0.5
3 5 7 9 10
7.6 12.7 17.8 22.9 25.4
3 6 8 11 12
7.6 15.2 20.3 27.9 30.5
3 9 13 16 20
7.6 22.9 33 40.6 50.8
4
0.1 0.2 0.3 0.4 0.5
6 9 12 15 17
15.2 22.9 30.5 38.1 43.2
6 10 14 19 23
15.2 25.4 35.6 48.3 58.4
7 17.8 15 38.1 25 63.5 30 76.2 Not Recommended
Table 14. Clearance for Coefficient of Friction ≥ 1.0; Site Class E Seismic Hazard Level
1
0920-30102-002
Building Period 0.1 0.2 0.3 0.4 0.5
Clearance, 1/4:12 slope inches cm 1 2.5 1 2.5 1 2.5 2 5.1 4 10.2
Clearance, 1/2:12 slope inches cm 1 2.5 1 2.5 1 2.5 2 5.1 4 10.2
Clearance, 1:12 slope inches cm 1 2.5 1 2.5 2 5.1 3 7.6 6 15.2
2
0.1 0.2 0.3 0.4 0.5
2 3 4 7 7
5.1 7.6 10.2 17.8 17.8
2 3 5 8 9
5.1 7.6 12.7 20.3 22.9
3 5 8 11 14
7.6 12.7 20.3 27.9 35.6
3
0.1 0.2 0.3 0.4 0.5
2 4 6 8 8
5.1 10 15.2 20.3 20.3
2 4 7 9 9
5.1 10.2 17.8 22.9 22.9
3 6 10 12 14
7.6 15.2 25.4 30.5 35.6
4
0.1 0.2 0.3 0.4 0.5
4 8 11 14 16
10.2 20.3 27.9 35.6 40.6
5 9 12 16 19
12.7 22.9 30.5 40.6 48.3
5 12 20 24 30
12.7 30.5 50.8 61 76.2
Solyndra Confidential
Design Guide 200 Series 21
Design in Seismic Areas
Table 13. Clearance for Coefficient of Friction ≥ 0.8; Site Class E
Design in Seismic Areas
4.3. A Note on Code Compliance The Solyndra system is designed to not be attached and to minimize lateral forces on the roof diaphragm as it acts as an isolation system. It is exempt from the prescribed requirements described in Section 1613 of the 2007 CBC (California Building Code) and Section 13.1.4 of ASCE 7- 05, under specific exemption for non-structural electrical components with weights of less than 400 pounds (182 Kg), mounted less than 4 feet (1.22 m) above floor level, provided that flexible connections are provided and testing has been done. The applicable code sections are shown in Table 15 for reference.
Table 15. A Selection of Applicable Seismic Codes 2007 CBC, Section 1613 EARTHQUAKE LOADS “1613.1 Scope. Every structure and portion thereof, including nonstructural components that are permanently attached to structures and their supports and attachments, shall be designed and constructed to resist the effects of earthquake motions in accordance with ASCE 7, excluding Chapter 14 and Appendix 11A. The seismic design category for a structure is permitted to be determined in accordance with section 1613 or ASCE 7.” ASCE 7-05, Chapter 13 SEISMIC DESIGN REQUIREMENTS FOR NONSTRUCTURAL COMPONENTS “13.1.4 Exemptions. The following nonstructural components are exempt from the requirements of this section: 4. Mechanical and electrical components in Seismic Design Categories D, E, or F, where the component importance factor, Ip, is equal to 1.0 and both of the following conditions apply: a. Flexible connections between the components and associated ductwork, piping, and conduit are provided, and b. Components are mounted at 4 ft (1.22 m) or less above a floor level and weigh 400 lb (1780 N) or less.“ 2007 CBC, Section 1708.5 “1708.5 Seismic qualification of mechanical and electrical equipment. The registered design professional in responsible charge shall state the applicable seismic qualification requirements for designated seismic systems on the construction documents. Each manufacturer of designated seismic system components shall test or analyze the component and its mounting system or anchorage and submit a certificate of compliance for review and acceptance by the registered design professional in responsible charge of the design of the designated seismic system and for approval by the building official. Qualification shall be by an actual test on a shake table, by three-dimensional shock tests, by an analytical method using dynamic characteristics and forces, by the use of experience data (i.e., historical data demonstrating acceptable seismic performance) or by a more rigorous analysis providing for equivalent safety.”
22
Design Guide 200 Series
Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
5.1. Solyndra Panels & Mounts The Solyndra 200 Series Panel System is a tool-less panel installation system requiring no fasteners; it simply snaps together. It consists only of Panels and Panel Mounts. The 200 Series Cable Management System simplifies wiring and requires no tools for assembly. Solyndra offers optional Snow Mounts and Load Distribution Feet (LDF). Figure 18 shows a six-panel system with Panel Mounts, optional Snow Mounts, and the Cable Management System.
Figure 18. Solyndra Panel Mount System
Panel
Panel Mount
Snow Mount
Cable Trough Clip
Cable Trough
Table 16 lists the standard parts in Solyndra systems.
Table 16. Panel Installation Hardware - Provided as Balance of System Item
Order Number
Description
Panel
SL200-XXX
Solyndra photovoltaic panel. -XXX represents the power rating.
Panel Mount
SLN-230
Panel Mount for Solyndra 200 Series photovoltaic panel.
Dust Cap for Male Solarlok Connectors
0048-30100
May be used to cover unused Solarlok male connectors. Dust Cap for Female Solyndra Connectors
0048-30094
May be used to cover unused Solarlok female connectors
0920-30102-002
Solyndra Confidential
Design Guide 200 Series 23
Solyndra Panel System
Chapter 5 Solyndra Panel System
Solyndra Panel System
5.2. Solyndra Cable Management System Table 17 lists the components in the Solyndra Cable Management System. Refer to “2.2. String Blocks” on page 7 for information on routing home run cables within arrays.
Table 17. Solyndra Cable Management System Item Long Cable Channel
Order Number
Illustration
SLC-2TE
Used for routing the home-run cables around and within the array. Short Cable Channel
SLC-2TN
Used for routing the home-run cables around and within the array. Cable Channel Peg
SLC-2CN
Cable Channel Pegs are installed on the sides of the array. They support the Short Cable Channels that contain the home-run connections. Cable Channel Hanger
SLC-2CE
Cable Channel Hangers are installed on the sides of the array. They support the Long Cable Channels that contain the home-run connections. Panel Mount Cable Channel
SLC-2DE
Used in corner wiring and certain other cases.
5.3. Optional Panel Mounting Components Solyndra offers a Snow Mount for use in high snowfall areas. It increases the snow rating from 1200 Pascals (25 PSF) to 1850 Pascals (38.6 PSF). A Load Distribution Foot (LDF) is available for mineral wool roofs and other applications which require a more distributed load. Refer to “5.5.1. Snow Loads” on page 26 for details.
Table 18. Optional Snow Mount and Load Distribution Foot Item Snow Mount
Part Number
Illustration
SLM-2DS
Used at the center of the Panel side rails to increase the snow load rating.
Load Distribution Foot
SLL-340
Used on mineral-wool or other ‘soft’ roofs. The standard Panel Mount rests on the LDF, which allows the LDF to tilt slightly to accommodate uneven roof surfaces.
5.3.1. Determining the Required BOS Parts Quantities The Solyndra CAD Tool has attributes that allow part counts to be extracted from designs. See “Chapter 7 Solyndra CAD Toolkit” on page 31 for details. 24
Design Guide 200 Series
Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
A certain number of panel mounts, cable management components, and dust caps are included with each panel at no additional charge. The quantities are based on a typical 8 x 12 panel rectangular sub-array. Table 19 lists the standard ratios. Note that the exact quantities shipped will vary due to the standard packaged quantity of each component. For example, Long Cable Channels are shipped in minimum quantities of 15 per box. The actual quantities required will depend on sub-array size and shape, and therefore will vary by project. For small or irregularly-shaped sub-arrays, additional components may be ordered separately.
Table 19. Standard Configuration BOS Component Ratios BOS Component
Order Number
Units per Panel
Ratio
Panel Mount
SLN-230
5 mounts to 4 panels
1.25
Dust cap for male connectors
-
1 cap to 1 panel
1
Dust cap for female connectors
-
1 cap to 1 panel
1
Long Cable Channel
SLC-2TE
1 channel to 20 panels
0.05
Short Cable Channel
SLC-2TN
7 channels to 50 panels
0.14
Cable Channel Hanger
SLC-2CE
3 hangers to 20 panels
0.15
Cable Channel Peg
SLC-2CN
7 clips to 25 panels
0.28
Panel Mount Cable Channel
SLC-2DE
1 protector to 20 panels
0.05
Snow Mount
SLM-2DS
0
0
Load Distribution Foot (LDF
SLL-340
0
0
Use of Non-Approved Hardware Do not substitute for Solyndra-specified parts without the express written consent of Solyndra. Use of nonSolyndra-specified parts will void the warranty. Materials used outdoors should be sunlight/UV resistant. Materials such as wire insulation and other components should be certified to withstand the temperatures to which they are exposed.
Tyco Solarlok Connector Information Table 20 lists part numbers for Tyco Solarlok connectors for 10 AWG (5.3 mm2) wire, commonly used for home run connections. Table 21 lists part numbers for Tyco Solarlok connectors for 12 AWG (4 mm2). These should be used if it is necessary to replace a connector on a Solyndra panel.
Table 20. Tyco Solarlok Connector Part Numbers, 10 ga (5.3 mm2) Wire Female Cable Connector
Male Cable Connector
Plus Keyed
Minus Keyed
Plus Keyed
Minus Keyed
Plus Coupler
5-1394462-5
-
1394461-7
-
Minus Coupler
-
5-1394462-5
-
1394461-8
Male Coupler, Neutral
-
-
Unkeyed 6-1394461-3
Table 21. Tyco Solarlok Connector Part Numbers, 12 ga (4 mm2) Wire Female Cable Connector
Male Cable Connector
Plus Keyed
Minus Keyed
Plus Keyed
Minus Keyed
Plus Coupler
1394462-3
-
1394461-3
-
Minus Coupler
-
1394462-4
-
1394461-4
Male Coupler, Neutral
-
-
Unkeyed
0920-30102-002
Solyndra Confidential
6-1394461-2
Design Guide 200 Series 25
Solyndra Panel System
5.4. Standard Configuration
Solyndra Panel System
5.5. Roof Loads All roof-top photovoltaic designs should be reviewed by a qualified structural engineer. The following data should be considered as advisory only. The roof deck may be made of any material as long as it is securely fastened, has a slope of 2:12 or less, can support the load, and provides proper friction. High-reflectivity white material is preferred; lower-reflectivity roofs will reduce energy output. Solyndra offers a Load Distribution Foot (LDF) for installation situations which must meet a local pressure loading limit.
Figure 19. Solyndra LDF with Mount on Top
Table 22. Distributed Roof Load, Standard Panel Mount and LDF Mount Panel Wt.
Panel Area
31.8 Kg
2.49 m2
2.3 Kg
70 lbs
26.8 ft
5 lbs
2
Standard Mount Distributed Load Wt.
LDF Wt.
Distributed Load w/ 4 LDF
13.9 Kg/m2
2.05 Kg
14.9 Kg/m2
metric
2.84 psf
4.5 lbs
3.05 psf
imperial
The values in Table 22 assume an average of 1.22 panel mounts per panel; correct for an 8 by 12 array. From a design viewpoint, adding an array to a roof adds 2.84 lbs/ft2 (13.9 kg/m2) of distributed load to the roof. However, in some cases the roof ’s live load allowance of 20 lbs/ft2 (100 kg/m2) may be eliminated in those areas covered by panels because it will no longer be possible to walk in areas occupied by the array.
5.5.1. Snow Loads Solyndra 200 Series Panels have been tested per Section 10.16 of IEC 61646. They can withstand 25 pounds per square foot (122 kg/m2, or 1200 Pascals) of snow load when mounted on the standard fourcorner mount system. For locations that require snow load ratings between 1200 and 1850 Pascals (25 and 38.6 PSF), two Snow Mounts mounts can be placed under the panel rails, at the mid-point. These Snow Mounts increase the rating to 38.6 pounds per square foot (189 kg/m2, or 1850 Pascals). Note that each Snow Mount is supporting two panels.
26
Design Guide 200 Series
Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
Table 23. Snow Load Contact Pressure – Metric Units Snow Load
Total Weight
Pressure per Mount Panel Mounts at corners only
Pressure per Mount, with LDF
Panel Mounts + Snow Mounts
Panel Mounts at corners only
Panel Mounts + Snow Mounts
Pascals
Kg/m2
Kg
KPa
Kg/m2
KPa
Kg/m2
KPa
Kg/m2
KPa
Kg/m2
0
0
0
9.43
962
4.76
485
1.06
108
.563
57
300
30.6
76.0
30.1
3073
15.1
1541
3.25
331
1.66
169
690
70.4
175
57.1
5819
28.6
2914
6.10
622
3.08
315
900
91.8
228
71.6
7297
35.8
3653
7.64
779
3.85
393
1200
122
304
92.3
9409
46.2
4709
9.83
1002
4.95
505
1515
154
384
6.10
622
1850
189
469
7.32
747
Not permitted
57.0
5817
68.6
6996
Not permitted
Table 24. Snow Load Contact Pressure – Imperial Units Snow Load
psf
Total Weight
psi
Pressure per Mount Panel Mounts at corners only
Pressure per Mount, with LDF
Panel Mounts + Snow Mounts
Panel Mounts at corners only
Panel Mounts + Snow Mounts
lbs
psf
psi
psf
psi
psf
psi
psf
psi
0
0
0
197
1.36
99.1
0.688
22.0
0.153
11.7
0.081
6.27
0.044
168
629
4.37
315
2.19
67.8
0.471
34.6
0.240
14.4
0.100
385
1191
8.27
597
4.14
127
0.885
64.4
0.447
18.8
0.131
503
1494
10.4
748
5.19
159
1.11
80.4
0.559
25.1
0.174
670
1927
13.4
964
6.70
205
1.43
103
0.718
31.6
0.220
846
1191
8.27
127
0.885
38.6
0.268
1006
1433
9.95
153
1.06
Not permitted
Not permitted
Snow Loads for Mineral Wool Insulated Roofs Mineral wool insulated roofs have a maximum pressure rating in order to insure that the material is not crushed. When installing with the LDF on a mineral wool insulated roof, determine the pressure rating of the insulation. Table 25 shows the maximum snow loads for Rockwool roofs in good condition, and other lesser mineral wools.
Table 25. Maximum Snow Loads on Mineral Wool Insulated Roofs Mount Arrangement Panel Mounts with LDF Panel Mounts + Snow Mounts. all with LDF
0920-30102-002
Roof Type
Maximum Snow Load Pascals
Kg/m
psf
psi
1200
122
25.1
0.174
Lesser Mineral Wools
650
66.3
13.5
0.094
Rockwool
1850
189
38.6
0.268
Lesser Mineral Wools
1500
153
31.3
0.218
Rockwool
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Solyndra Panel System
5.5.2. Roof Mount Point Loads
Solyndra Panel System
5.5.3. Hail Solyndra panel hail specifications are shown in Table 26. When planning installations, check historical weather data to determine the possibility of receiving hail in excess of the panel’s hail specification.
Table 26. Hail Specification Specification
Size
Mass
Velocity
Hail
25 mm
7.53 g
23 m/s
5.5.4. Construction Materials Placement In addition to combined loads, the roof must withstand live loads during installation. Solyndra panels are packed horizontally onto pallets for shipment. A full crate of 13 panels weighs approximately 1150 lbs (520 kg). Refer to Solyndra’s shipping documentation for exact weight and size. Have a qualified structural engineer verify that the roof structure will not be overloaded from the combination of live loads and pallets on the roof.
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Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
An inverter never needs to be rated at the same Wp as the array. Figure 20 shows how the power output varies over the course of the year, from the best (summer) days to the worst (winter) days. The hour-byhour variation in power output over the year can be plotted as a histogram, showing the number of hours in each year which reach a given power level. The histogram shows that only on a few days of the year is the output power close to the Wp value; on most days it is significantly less. This is especially true at more northern latitudes.
Figure 20. Annual Power Output Variation & Histogram 100
80 60
Panel Power Output; Brightest Days Percentage of Wp
Percentage of Wp
100
Intermediate Panel Power Outputs
40
Panel Power Output; Darkest Days
20 0
80 60 40 20 0
6 AM
9 AM
Noon
3 PM
6 PM
1
Hourly Data
4000
Actual Power versus Wp Rating The actual power produced by a panel is usually less than the Wp rated power for three reasons: • The sun is usually not as intense as the 1000W/m2 used for measuring Wp. • Power decreases as temperature increases, and the panel is usually warmer than the 25°C temperature used for measuring Wp. This is especially likely to be the case in the summer. • The panel is not aimed directly at the sun; that is, it is not perpendicular to the sunlight.
6.1. Inverter Sizing A typical solar array will seldom generate the STC-rated power. The inverter can and should be smaller. The amount depends on both technical factors and economic factors.
Technical Factors Solyndra’s energy yield forecast tool produces an hour-by-hour forecast of energy production. From this, the peak power produced by the array can be determined. An inverter sized to this value will be sufficient. As an example, a nominal 250 kW array installed in Sacramento, California will produce, for a few days around June 22nd, a maximum of 206 kW. This is the peak output, so an inverter of 210 kWp is sufficient for this array.
Economic Factors It may make economic sense to use an even smaller inverter than the technical factors alone suggest. Inverters are not harmed by being connected to an array which produces more watts than the inverter rating. The inverter simply de-tunes the array, an effect known as clipping. In the above example, a 200 kW inverter will sacrifice only 0.2% of total energy; a 180 kW inverter will sacrifice only 3.6%. The Levelized Cost of Energy (LCOE) metric is an useful indicator of the optimum inverter size, as it accounts for both the cost benefit and the lost energy penalty. Figure 21 shows the LCOE for different inverter sizes for the nominal-250 kW example system. At the ratio of 1.45, the inverter size is 172.4 kW, for a loss of only 8.4%.
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Optimum Inverter Selection
Chapter 6 Optimum Inverter Selection
Optimum Inverter Selection
Solyndra offers an Excel spreadsheet tool that will automatically import the hourly data from the energy yield model and evaluate the performance of various inverter sizes.
Figure 21. LCOE vs DC:AC Ratio & NPV vs DC:AC Ratio $0.256 $0.254
$700 1.75 $600 $500 $400 $300 $200 $100 $0 1.00 1.20 1.40 1.60 1.80 2.00 DC:AC Ratio
$0.250
NPV
LCOE
$0.252 $0.248 $0.246
1.45
$0.244 $0.242 1.00
1.20
1.40 1.60 DC:AC Ratio
1.80
2.00
6.1.1. Maximizing Value for AC-Limited Incentive Applications Some feed-in tariffs are tied to the AC rating of the inverter, rather than the DC output of the array. There are breakpoints in the FIT at various AC sizes. This incentive system means that the economic goal is to determine the most cost-effective DC array size for a given AC inverter rating. This DC-to-AC ratio is called the oversize ratio. There is an optimum oversize ratio which will maximize the net present value (NPV) of the project to the investor. Figure 22 shows the economically-optimum oversize ratio for an array installed where there is a change in FIT rates for a 250 kW-rated inverter. At a 1.75 ratio, the array is 437.5 kWp. A 250 kWp array at this location will yield 302 MWh of energy. By increasing the array size to 437.5 kWp, the total energy yield increases to 392 MWh. This is illustrated in Figure 22. The area in red is the energy lost; the area in green is the energy gained due to the oversize array.
Histogram of Hourly Energy Output
400 350 300 250 200 150 100 50 0
Clipped Optimized 1.2 DC:AC Ratio
1 218 435 652 869 1086 1303 1520 1737 1954 2171 2388 2605 2822 3039 3256 3473 3690 3907 4124 4341
1.2 DC:AC Ratio
kW Output
400 350 300 250 200 150 100 50 0
1 218 435 652 869 1086 1303 1520 1737 1954 2171 2388 2605 2822 3039 3256 3473 3690 3907 4124 4341
kW Output
Figure 22. Energy-Cost Trade-off for Oversized Array
Histogram of Hourly Energy Output
6.2. Summary In all cases, it makes sense to determine the actual power output of the array, and size the inverter accordingly. In most cases, it will make economic sense to select an inverter somewhat smaller than the actual peak power output of the array, especially at more-northern latitudes. The precise oversize ratio will depend on the tariff regimen, actual insolation, and inverter cost. Regardless of the tariff, Solyndra’s Excel tool can be used to evaluate inverter size options. Solyndra’s Design Team can also assist in determining the optimum inverter size.
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Design Guide 200 Series
Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
The Solyndra CAD Toolkit is an AutoCAD .DWG file with blocks representing Solyndra panels and mounting system components. The blocks have been assigned attributes that make it possible to extract parts counts from a drawing. Additional files in the CAD tools folder are provided to assist with this extraction process. The toolkit includes two AutoCAD .DWG files. One is based on U.S. standard units and the other is based on SI (metric) units.
Layers Layers have been assigned to drawing elements to allow the designer to control the desired level of visible detail in a drawing. The defined layers are: SOL-PANEL CONNECTIONS
SOL-COMPONENT HANDLES
SOL-BLOCK DESCRIPTIONS
SOL-CABLE CHANNELS
SOL-SHEET OBJECTS
SOL-STRING BRANCHES
SOL-PANEL MOUNTS
SOL-PANELS
SOL-PROOFING
SOL-ATTRIBUTES
The SOL-PROOFING layer displays colored indicators of the different panel assembly blocks. There are four color coded panels in the CAD Toolkit. This color coding provides visual cues that allow the designer to quickly verify that the correct panel and array blocks were used in creating an array design. The yellow (TL) panel is always in the upper left corner of the sub-array. The light blue (T) panel is the top row of the sub-array, excluding the upper left corner panel. The pink panel (L) is the left edge of the sub-array, excluding the upper left corner panel. And the dark blue (F) panel is the remaining fill of the sub-array.
Blocks The parts required for a Solyndra installation are drawn as blocks in the Model space. The panel block contains “handles” for attaching the other mounting system parts. The Model space also contains blocks containing pre-built sub-arrays for typical stringing configurations. These sub-array blocks have been built up from the individual parts blocks and can be used as building blocks for assembling larger arrays. Where an array section calls for a configuration not provided in the pre-built sub-arrays, the designer can build up that array section from detailed panel and parts blocks. Each block may be copied from the example already inserted in the Model space or accessed from the Insert Block menu.
Panel Details The Panel Details sheet contains blocks for individual parts and single panel assemblies. Panels are drawn to scale; panel dimensions have been increased slightly to allow for typical spacing between panels when installed. Panel Mounts (feet only) are drawn to scale and positioned accurately on the panel. All other parts are symbolic representations and are not drawn to scale.
Vertical String Blocks & Horizontal String Blocks The Vertical String Blocks sheet contains blocks of pre-built strings and sub-arrays with panels arranged in typical vertical (or horizontal) stringing configuration.
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Solyndra CAD Toolkit
Chapter 7 Solyndra CAD Toolkit
Solyndra CAD Toolkit
Attributes Each individual part block has text attributes attached to it, which allow parts counts to be extracted from a drawing. The attributes assigned to each part block are as follows: Block Name
Attributes
Description
Default qty
PANEL_W_ANCHOR
PANELS
Panel
1
PANEL_MNT
PANEL_MOUNT
Panel Mounts
1
CABLE_CHANNEL_LONG
CABLE_CHANNEL_LONG
Long cable channel
1
CABLE_CHANNEL_SHORT
CABLE_CHANNEL_SHORT
Short cable channel
1
Important Note: To avoid clutter in the drawing, the attributes are set as “Invisible” and “Constant”. If the blocks are exploded, the attributes will appear in the model space, and they will no longer be attached to a block and will prevent counting of parts.
Mounting BOS Extraction (ATTEXT) The attribute extraction command, ATTEXT,* can be used to extract Solyndra mounting system parts counts for a completed array layout design. After entering the ATTEXT command a dialogue box will appear. Follow these instructions to extract attributes to a comma-delimited file which can be used to get a total parts count for the Solyndra mounting system. 1. Choose Comma Delimited File. 2. Click on Select Objects, and select the portion of the drawing for which it is desired to determine the parts count. 3. If the template file field is blank, click the button and locate SOL_BOM_NOTEPAD_TEMPLATE.TXT on the computer. (This file is in the Solyndra CAD Toolkit folder.) 4. Click the Output File button to select the location for the output text file. The default file name is the name of the drawing file. Note that in order to ensure the template file is not overwritten, name the output file differently from the template file, and click OK. 5. There is now a text file with a line for each block instance, and values for the associated attributes separated by commas. 6. Locate and change its file extension to “.csv”; open the file with Excel, select all and copy. 7. Open the Solyndra BOS summary template Excel file (“[Solyndra] bos summary template.xls”). 8. Paste the copied data from the extract file into the location in the BOS summary template spreadsheet. The spreadsheet will total the number of panels and the parts counts extracted from the drawing. The spreadsheet will also compute an average parts per panel value for each mounting system component. 9. Save and close the BOS summary template file. Note that if it is desired to keep the original for later use, the working copy must be saved to a different directory and/or file name from the master copy. *The spelling of the attribute extraction command differs depending on the language in which AutoCAD is used. • English – ATTEXT • Czech – ATREXT • German – ATTEXT • French – ATTEXTR • Spanish – ATREXT • Italian – ESTRATT • Portuguese – EXTRATRIB • Russian – АТЭКСП
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Design Guide 200 Series
Solyndra LLC • 47488 Kato Road • Fremont CA 94538 • www.solyndra.com
0920-30102-002
Revision History Revision
Part Number
Date
Notes
1.0
0920-30102-001
2010-08-10
Initial Version
1.1
0920-30102-002
2011-04-01
Updated for LLC
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Design Guide 200 Series 33
Solyndra Quality Policy Solyndra provides state-of-the-art solar photovoltaic systems and expert support that meet customers’ expectations for quality, delivery, technology, and responsiveness. We are committed to continually improving the quality of our products and processes. Design Guide 200 Series
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