PV Installer Program-Participant Guide

Introduction to Solar Energy

© 2011 Underwriters Laboratories Inc.

Solar Energy An in-exhaustible source of Energy which God has bestowed on us

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Solar Energy is a Electro Magnetic Wave Radiation • • • •

Radiation emanated from the sun at a temperature of 5000 o K Magnetic Wave travels a distance of 1.5 * 10 8 km The Sun subtends and angle of 32’ with the earth Solar Constant i.e. Solar Radiation of 1395 W / m 2 in space

Electro Magnetic Wave Radiation Gamma Rays 10 – 8 to 10 – 4 µ m X – rays 10 – 5 to 10 – 2 µ m Ultraviolet 10 – 2 to 1 µ m Visible Spectrum 0.38 to 0.78 µ m Thermal Radiation – near infrared and far infrared 1 to 10 + 3 µ m • Radar, T V and Radio 10 + 3 to 10 + 10 µ m • • • • •

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Position of the Sun

Azimuth angle of the sun: Often def ined as the angle f rom due north in a clockwise direction. (sometimes f rom south) Zenith angle of the sun: Def ined as the angle measured f rom v ertical downward.

Path of the Sun

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 Decl ination = 23.45 * Si n (360*(284+n)/365)  Opti mum Ti lt angle = La titude

for the ma ximum collection through out the year § Sea son Optimization tilt = (La titude - Declination)  El evation and Azimuth Cos θZ = Si n δ * Si n φ + Cos δ * Cos φ * Cos ω α = 90 - θZ

Solar Path Diagram http://andrewmarsh.com/blog/2010/01/04/solar-position-and-sun-path

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Horizontal & Vertical Shadow http://andrewmarsh.com/blog/2010/01/10/horizont al-and-verticalshadow-angles

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Solar Radiation Global Direct Diffused Global = Direct + Diffused

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Photovoltaic

© 2011 Underwriters Laboratories Inc.

Physics of Photovoltaic Generation

n-type se miconductor + + + + + + + + + + + + + + + - - - - - - - - - - - - - - - - - -

De ple tion Zone p-type se miconductor

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How PV Cell produce Electricity:

► When rays of sunlight hit the solar cell electrons are ejected from the atoms.

► Electrons are knocked loose from their atoms, which allow them to flow through the PN Junction to produce electricity.

Working of Solar Cell Video

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Solar PV Markets Capacity installed in 2011

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PV Module Production, Supply, and Demand Metrics

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Output vs Technology at Bellary, Karnataka State

Output vs Technology at Bangalore, Karnataka State 1,905.2

Electricity Exported to The Grid(MWh) For Fixed Tilt

Electricity Exported to The Grid(MWh) For Fixed Tilt

1,950.0 1,862.5

1,900.0

1,820.4

1,850.0 1,800.0

1,750.0 1,750.0 1,712.0

1,750.0 1,700.0 1,650.0 1,600.0 a-si

Cd-Te

CIS

Mono-si Poloy-si

1,928.0

1,950.0

1,879.4

1,900.0

1,830.4

1,850.0 1,800.0

1,751.5 1,751.5 1,710.1

1,750.0 1,700.0 1,650.0 1,600.0 a-si

HIT

1,893.1

1,900.0

1,845.1

1,850.0 1,767.2 1,767.2

1,800.0 1,726.0

1,750.0 1,700.0 1,650.0 a-si

Cd-Te

CIS

Mono-si Poloy-si

2050.7 2,053.10 2053.1

2,060.00 2,028.60

2,040.00 2,020.00 1,990.20

2,000.00

1966.4

1,980.00 1,960.00 1,940.00

Corpora te Communication

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1,920.00 a-si

Cd-Te

CIS

Mono-si

Poly -si

HIT

One-axis Polar Two-axis

Percentage Increase vs Technology at Bangalore, Karnataka 27.3

27.2

27.1

20.0 10.0 0.0 CdTe

CIS

Mono-si Poly -si

HIT

Percentage Increase vs Technology at Leh, Jammu & Kashmir

30.0

30.4 21.0

35.2 30.3

21.3

35.0

34.9

30.3

30.2 21.7

21.5

35.5

35.0

30.4

30.3 21.5

One-axis Polar Two-axis

20.9

20.0 10.0 0.0 CdTe

CIS

Mono-si Poly -si

HIT

29.4

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25.5

29.3 25.5

a-si Cd CIS Mo Pol HIT Te no- y-si si Bangalore 1,8621,8201,7121,7501,7501,905 Brllary 1,8791,8301,7101,7511,7511,928 Charanka 1,8661,8141,6901,7321,7321,917 Jaisalmer 1,8661,8141,6901,7321,7321,917 Leh 1,9902,02820512,0532053 1966

30.0 21.0

21.2

21.6

HIT

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27.8

27.7

27.6

28.0

27.7

24.4 24.3 24.3 24.3 24.3 24.3 22.6 22.4 22.4 22.3 22.1 22.0

30.0 20.0 10.0 0.0

a-si

CdTe

30.9 40.0

26.8

30.0

CIS

Mono-si Poly -si

HIT One-axis Polar Two-axis

30.7 26.8

21.7

21.5

22.1

26.8 21.9

31.0

30.5 26.8

21.9

26.8 21.3

10.0 0.0 a-si

25.5 21.4

30.5

30.4 26.7

20.0

29.1

29.0 25.5

Mono-si Poloy-si

Leh Charanka Bangalore

CdTe

Percentage Increase vs Technology at Charanka, Gujarat Percentage Increase in Output

a-si

CIS

Percentage Increase vs Technology at Jaisalmer, Rajasthan Percentage Increase in Output

35.4 40.0

Cd-Te

2,500.0 2,000.0 1,500.0 1,000.0 500.0 0.0

27.9

24.0 24.0 24.0 23.9 23.9 23.9 22.8 22.7 22.7 22.6 22.5 22.4

a-si

1,732.5 1,732.5 1,690.0

Output vs Technology for Fixed Tilt

27.5

27.2

1,814.7

Percentage Increase vs Technology at Bellary, Karanataka Percentage Increase in Output

27.4

30.0

HIT

1,866.6

a-si Electricity Exported to the Grid (MWh)

Electricity Exported to The Grid(MWh) For Fixed Tilt

Mono-si Poloy-si

1,917.5

1,950.0 1,900.0 1,850.0 1,800.0 1,750.0 1,700.0 1,650.0 1,600.0 1,550.0

HIT

Output vs Technology at Leh, Jammu & Kashmir State

Percentage Increase in Output

CIS

1,941.0 1,950.0

1,600.0

Percentage Increase in Output

Cd-Te

Output vs Technology at Charanka, Gujarat State Electricity Exported to The Grid(MWh) For Fixed Tilt

Electricity Exported to The Grid(MWh) For Fixed Tilt

Output vs Technology at Jaisalmer, Rajasthan State

29.5

29.1 25.5

21.4

CIS

Mono-si Poly -si

HIT

One-axis Polar Two-axis

25.5 20.9

20.0 10.0 0.0 Corpora te CdTe Communication a-si CIS Mono-si Poly -si

HIT

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Fixed One-axis Polar

0.60 0.40 0.20

0.45 0.46 0.52 0.43 0.45 0.27 0.31 0.49 0.22 0.41 0.30 0.40 0.26 0.21 0.28 0.40 0.33 0.34 0.20 0.25 0.23 0.16 0.20

0.00

Fixed One-axis Polar

0.40

0.20

0.44 0.44 0.43 0.26 0.42 0.41 0.20 0.24 0.35 0.25 0.23 0.20 0.34 0.24 0.35 0.29 0.19 0.22 0.15 0.18 0.20

0.6 0.4

0.2

0.00

0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.2 0.4 0.2 0.2 0.3 0.2 0.2 0.2 0.2 0.3 0.3 0.2 0.2 0.3 0.2 0.2 0.2

0.0

0.60

0.40 0.20

0.44 0.43 0.36 0.42 0.43 0.35 0.41 0.25 0.42 0.23 0.20 0.35 0.24 0.19 0.23 0.34 0.24 0.34 0.28 0.19 0.22 0.19 0.15 0.18

0.00

Output MWh/sq.mtr. vs Technology at Charanka, Gujarat

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0.50 0.40 0.30 0.20

0.44 0.43 0.36 0.42 0.43 0.35 0.40 0.41 0.23 0.25 0.34 0.20 0.23 0.24 0.34 0.33 0.19 0.22 0.23 0.28 0.18 0.15

Fixed One-axis Polar

Output MWh/sq.mtr. vs Technology at Bellary, Karnataka Output MWh/sq.mtr.

0.60

Output MWh/sq.mtr.

Output MWh/sq.mtr.

Output MWh/sq.mtr. vs Technology at Jaisalmer, Rajasthan 0.45 0.45 0.44

Fixed One-axis Polar

Output MWh/sq.mtr. vs Technology at Bangalore, Karnataka Output MWh/sq.mtr.

Output MWh/sq.mtr.

Output MWh/sq.mtr. vs Technology at Leh, Jammu & Kashmir 0.54

Fixed One-axis Polar Two-axis

0.19

0.18

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0.00 Corpora te Communication

Performance rating Technical

Commercial Cost Driven rating for fixed tilt at different places

Performance rating for fixed tilt at different places Bellary Jaisalmer

Bijapur Leh

Charanka

19.00

19.00

17.00

17.00

15.00

15.00

13.00

13.00

11.00

11.00

9.00

9.00

7.00

7.00

Bellary Jaisalmer

Bijapur Leh

a-Si

CIS

Charanka

5.00

5.00 a-Si

CdTe

CIS

mono-Si Poly-Si

HIT

CdTe

mono-Si

Poly-Si

HIT

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THANK YOU.

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Inspection Plan of Civil Foundations for Solar Power Plants

© 2011 Underwriters Laboratories Inc.

Standard References 

IS 1498:1970 – Classification & identification of soils for Engineering purposes



IS: 1199 – 1959 – Tests on fresh concrete

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IS: 13311 (Part 1,2) – 1992 – Tests on hardened concrete

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IS 516:1959 – Methods of tests for strength of concrete

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IS: 2720 (Part II) – 1973 – Tests on soil – To determine w ater content in soil

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IS: 2720 (Part 4) – 1985 - To determine the particle size distribution of soil

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IS: 2720 (Part 5)–1985-To determine the liquid lim it and plastic limit of soil

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IS: 2720 (Part 8) – 1983 - To determine the maximum dry density and the optim um m oisture content of soil

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Contents: ► Introduction to soil types for foundations

► Introduction to foundations ► Foundations types used for Solar power plants

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Introduction to Soil types for Foundations

© 2011 Underwriters Laboratories Inc.

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Soil Map of INDIA:

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What is Soil? Organics 5%

Water 25%

Mineral 45%

Air 25%

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Minerals

GRAVEL

SAND

Clay

Silt

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Soil Groups Soil Type

Gravel – G Sand – S Silt – M Clay – C Organic – O

Gradation

Well Graded – W Poorly Graded – P

Plasticity

High Plasticity – H Low Plasticity – L

Soil type & particle size distribution as follows:

• Gravel : 80 – 4.75 mm • Sand : 4.75mm – 0.075mm (75 micron) • Silt

: 75 – 2 micron

• Clay

: less than 2 micron

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Estimated Soil Load Bearing Capacities Soil Type

Allowable Bearing (lb/ft2 - Pound per square foot )

Drainage

BEDROCK

4,000 to 12,000

Poor

GRAVELS

3,000

Good

SAND

2,000

Good

SILT

1,500

Medium

CLAY

1,500

Medium

ORGANICS

0 to 400

Poor

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Soil Layers:

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Soil Strength Classification for Foundations Sand and gravel – Best Medium to hard clays – Good Soft clay and silt – Poor Organic silts and clays – Undesirable Peat – No Good / Avoid Peat is an accumulation of partially decayed vegetation matter or organic matter.

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Laboratory tests for Soil Follow ing laboratory tests are to be carried out to determine the physical and engineering properties of soil samples: 1. Dry density and moisture content - (IS 2720 part – 2 & 29)

2. Particle size analysis

- (IS 2720 part – 4:1985)

3. Specific gravity

- (IS 2720 part– 3/sec2:1980)

4. Shear test

- (IS 2720 part – 11:1986)

5. Consolidation test

- (IS 2720 part – 15:1986)

6. Free swell test

- (IS 2720 part – 40:1977 & 41:1977)

7. Consistency Limits

8. Chem ical Analysis of representative soil samples

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Soil Samples Disturbed samples: which do not represent exactly how the soil was in its natural state before sampling.

► Disturbed samples are used for the more simple tests that will be performed and particularly for those tests which can be performed by self in the field. Undisturbed samples: which represent exactly how the soil was in its natural state before sampling. ► Undisturbed samples are necessary for the more sophisticated tests which must be performed in the laboratory for more detailed physical and chemical analyses. Undisturbed samples must be collected with greater care for they should represent exactly the nature of the soil.

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Sample Soil Test Report

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Introduction to Foundations

© 2011 Underwriters Laboratories Inc.

Definition of foundation The soil beneath the structures responsible for carrying the loads is called FOUNDATION. The general misconception is that the structural element which transmits the load to the soil(such as a footing) is the foundation. The figure below clarifies this point.

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Forces acting onto Foundation

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Classification of Foundations Shallow Foundations  Deep Foundations 

► Shallow foundations are placed at a shallow depth beneath the soil

surface. They include footings and soil retaining structures. The depth is generally less than the width of the footing and less than 3m. ► Deep foundations are commonly using piles. They are embedded very

deep into the soil. They are usually used when the top soil layer have low bearing capacity. Deep foundations are usually at depths deeper than 3m.

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Footing

Footing

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Shallow Foundation

P

Ground Surface

Column

P - Normal load

Df Footing B For Shallow Foundation = Df < 4B

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Deep Foundations

Pile

Shaft

Hammer Poured in place fill Ground Surface

Df

B

Pre bored hole

For Deep Foundation = Df > 4B 21

Laboratory tests for Concrete foundations ► Tests on Fresh Concrete 1. Slump test: To determine the strength of fresh concrete by slump test as per IS: 1199 - 1959.

2. Compacting factor test: To determine the strength of fresh concrete by compacting factor test as per IS: 1199 - 1959. 3. Vee-Bee test: To determine the strength of fresh concrete by using

a Vee-Bee consistometer as per IS: 1199 - 1959.

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Laboratory tests for Concrete foundations ► Tests on Hardened Concrete: 1. Non-destructive tests a. Rebound hammer test: To assess the likely compressive strength of concrete by using rebound hammer as per IS: 13311 (Part 2) - 1992. b. Ultrasonic pulse velocity test: To assess the quality of concrete by ultrasonic pulse velocity method as per IS: 13311 (Part 1) - 1992. 2. Compression test(Destructive): To determine the compressive strength of concrete specimens as per IS: 516 – 1959.

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Clear horizontal distance between reaction supports and test foundation a) For pad and chimney, grillages, concrete block foundations or buried anchors:

L = e + 0,7 x a (m) Where, e is the width of foundation in metres; a is the depth of foundation in metres; L is the distance between nearest points of reaction supports. b) For concrete piers, driven piles, drilled and grouted piles, or helix anchors: L = 3 x e (m)

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Figures:

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Sample Concrete Test Report

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Types of PV Foundation used for Solar Power Plants: This includes any of the following foundations:

 Concrete pier  Driven post  Screw piles  Precast or cast-in-place concrete ballast

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Concrete pier o Uses reinforcing bar to firmly connect the footing at the base to the concrete pier. o At the top, a metal post base connects the concrete pier to the mounting structure. o Make sure the bottom of the footing rests on undisturbed soil free of organic material.

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Driven pile systems

Driven pile systems are often found to be the more favorable choice based on cost, installation time, materials, and environmental impact. 29

Screw piles •

Screw piles are a steel screw-in piling and ground anchoring system used for structure foundations.

•

The pile shaft transfers a structure's load into the pile.

•

Screw piles are also known as ground screws

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Screw piles or Ground screws

Helical steel plates are welded to the pile shaft in accordance with the intended ground conditions.

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Precast or cast-in-place concrete ballast

 Ballasted footings are designed for mounting photovoltaic solar panels quickly.  Capable of relocation and reuse, the footings are intended for use in demanding applications, where panels need to be secured in unstable, environmentally sensitive, or impenetrable ground conditions. 32

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Pile Foundation for Solar PV - Video

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Ground Screw for Solar PV - Video

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THANK YOU

© 2011 Underwriters Laboratories Inc.

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Solar Photovoltaic (PV) System and Safety Measures

1

© 2011 Underwriters Laboratories Inc.

Key Elements of a PV System Energy source

load

power conditioning

PV Array

Inverter Charge Controller

Energy conversion

load center Energy distribution

Energy storage

Battery

Electric utility network

2 © 2011 Underwriters Laboratories Inc.

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Solar PV Safety involves 1. Working safely with photovoltaic systems

2. Conducting a site assessment 3. Selecting a system design 4. Adapting the mechanical design to the site 5. Adapting the electrical design to the site 6. Installing subsystem & components at site 7. Performing a system checkout and inspection

8. Maintaining and troubleshooting the system

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OSHA* Safety Categories * - Occupational Safety & Health Administration

> Personal Protection Equipment (PPE) > Electrical > Falls > Stairways and Ladders > Scaffolding > Power Tools > Materials Handling > Excavation

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Personal Protection Equipment (PPE)

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Personal Protection Equipment Responsibilities Employer Assess workplace for hazards. Provide personal protective equipment (PPE). Determine when to use. Provide PPE training for employees and instruction in proper use.

Employee Use PPE in accordance with training received and other instructions. Inspect daily and maintain in a clean and reliable condition.

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Examples of PPE Body Part

Protection Equipment

Eye

Safety Glasses, Goggles

Face

Face Shields

Head

Hard Hats

Feet

Safety Shoes

Hands and arms

Gloves

Bodies

Vests

Hearing

Earplugs, Earmuffs 7

Eye Protection

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Preventing Electrical Hazards: PPE  Proper foot protection (not

tennis shoes)  Hard hat(insulated nonconductive)  Rubber insulating gloves, hoods, sleeves, matting, and

blankets

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Selecting the Right Hard Hat Class A >General service (building construction, ship building, lumbering) > Good impact protection but limited voltage protection Class B > Electrical/utility work > Protects against falling objects and high-voltage shock and burns Class C > Designed for comfort, offers limited protection

> Protects against bumps from fixed objects, but does not protect against falling objects or electrical shock

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Hand Protection

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Electrical Injuries There are three main types of electrical injuries:

> Electrocution or death due to electrical shock > Severe burns > Falls (caused by shock)

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Dangers of Electrical Shock > Currents above 10 mA* can paralyze or “freeze” muscles.

> Currents more than 75 mA can cause a rapid, ineffective heartbeat & death will occur in few minutes unless a defibrillator is used.

> 75 mA is not much current – a small power drill uses 30 times as much.

* mA = milliampere = 1/1000 of an ampere

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Fall Protection Options

Personal Fall Arrest System (PFAS)

Guardrails

Safety Net

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Safety Line Anchorages Must be independent of any platform anchorage and capable of supporting at least 5,000 pounds (2268 kg)

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Ladder Angle Non-self-supporting ladders (that lean against a wall or other support): Position at an angle where the horizontal distance from the top support to the foot of the ladder is 1/4 the working length of the ladder.

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Grounding > Grounding creates a low resistance path from a tool to the earth to disperse unwanted current. > When a short or lightning occurs, energy flows to the ground, protecting you from electrical shock, injury and death.

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Improper Grounding >Tools plugged into improperly

grounded circuits may become energized.

>Broken wire or plug on extension cord

*Some of the most frequently violated OSHA standards

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Unsafe Installation Practices - Photos

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Unsafe Installation Practices - Photos

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THANK YOU

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Site Selection, Resource Assessment & Energy Yield Estimation

© 2011 Underwriters Laboratories Inc.

Photovoltaic System

1

Site Selection

Good Layout

3

Hapezoidal Layouts

Good Layouts

2

Improper Site Selection

Plan for Rock Blasting

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Compromising With Placing Modules

Embanking Soil to Level The Site

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Good Topography

Site Survey & Investigation Some of the other major factors that are to be considered are • Atmospheric effect on Solar Radiation • Daily and Seasonal Temperature Variations • Site proximity to natural disaster prone areas • Site climatic conditions with regards to wind speeds, saline atmosphere conditions etc. • Site land topography. This will impact on the civil foundation requirements • Proximity for power evacuation • Proximity to polluting industries • Easy site access 12

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Cognizance for site selection

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Solar Resource Assessment Step 1 Type the following link in the web browser http://eosweb.larc.nasa.gov/cgi-bin/sse/sse.cgi?

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Solar Resource Assessment Step 2 Click on Meteorology and Solar Energy section. The page as detailed below will be displayed

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Solar Resource Assessment Step 3 • Click on Enter Latitude and Longitude part of Data tables for a particular location. The following page will be displayed • This is known as Login screen. User has to enter – E-Mail ID – Password of his choice – Re enter the same password in third field

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Solar Resource Assessment Step 4 After entering all the details, by clicking on Submit button, the following screen will appear

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Solar Resource Assessment Step 5 • If the user is interested in solar radiation assessment in Delhi, one

has to enter the following values in the latitude and longitude field of the screen. Latitude : 28.38 N Longitude : 77.12 E After entering the values, the screen will be as shown. Then, Click on Submit

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Solar Resource Assessment Step 6 Choose parameters as per your requirement

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Solar Resource Assessment Step 7 Clicking on Submit provides the following output

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Energy Yield Estimation The following stage of evaluation is to carried out while designing / verifying • Weather data NASA / METEORNOM

• Simulation programme • Choice of system components (Max. efficiency components) • Software to be used - PVsyst - RETScreen - System Advisory Model

- TRANSYS - PYSOL

• Simulation • Analysis of yield 21

Energy Yield Estimation Case Study To design a 5MWp solar PV grid-connected power plant at a designated location in Bangalore Design Inputs • Site Details – Bangalore , Latitude-13 • DC Plate Rating – 5 MWp • Technology

0

Longitude- 77 0

– Thin Film Technology • Inverter – Central Inverter • Grid Voltage for Power Evacuation – 33 kV 22

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Energy Yield Estimation Option : Project design, System : Grid-Connected

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Energy Yield Estimation Click on Project

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Energy Yield Estimation Select ‘New Project’ enter the relevant data and then click ‘Site and Meteo’

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Energy Yield Estimation Enter relevant data

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13

Energy Yield Estimation Click ‘Open’ to enter the Location parameters of the site

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Energy Yield Estimation Geographical Parameters Enter Latitude, Longitude, Altitude etc. and go to ‘Monthly meteo’ tab to see the irradiation data

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14

Energy Yield Estimation Irradiation Data Irradiation unit can be chosen as required and click ‘OK’.

29

Energy Yield Estimation Situation & Meteo Situation and Meteo window appears click ‘Next’

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Energy Yield Estimation Operating temperature Depending on site choose summer operating temperature for Vmpp Min design (the default is 60⁰ C) and click ‘OK’

31

Energy Yield Estimation Orientation click on ‘Orientation’

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Energy Yield Estimation Tilt • Click ‘Unlimited Sheds’ enter the ‘Plane Tilt’, ‘Pitch’, ‘Coll. band

width’ and select the ‘Electrical Effect’ and click ‘Show Optimisation’

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Energy Yield Estimation Shading loss Shading Loss is displayed in this window. Close this window and ‘OK’

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Energy Yield Estimation System Click ‘System’

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Energy Yield Estimation Module and Inverter selection ‘Enter Planned Power’, ‘Select PV module’, ‘Select the inverter’

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Energy Yield Estimation String definition Select ‘Mod. In series’, enter ‘No. strings’ and click ‘Detailed Losses’

37

Energy Yield Estimation PV Filed losses (Thermal) Enter ‘NOCT coefficient’ as given in Module datasheet and go to ‘Ohmic Losses’ tab

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Energy Yield Estimation PV Field - losses (Ohmic) Enter ‘DC circuit loss fraction at STC’, choose ‘Significant length’ and enter ‘Loss fraction’, ‘External transformer’ and enter the ‘Iron loss’ & Inductive loss’ also enter the Vac and go to ‘Module Quality Mismatch’ tab.

39

Energy Yield Estimation PV Field – losses (Module Mismatch) Enter the ‘Mismatch Losses’ and go to ‘Soiling Loss’ tab

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Energy Yield Estimation PV Field - Losses (Soiling) Select the ‘Soiling Loss’ of 3% and go to ‘IAM Losses’ tab

41

Energy Yield Estimation IAM Losses Typical bo value is 0.03 for TF and 0.05 for crystalline and click ‘OK’

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Energy Yield Estimation Click OK

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Energy Yield Estimation Simulation Click ‘Simulation’

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22

Energy Yield Estimation Simulation Parameters Click ‘Simulation’

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Energy Yield Estimation Simulation Progress Click ’OK’

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Energy Yield Estimation Simulation Results Click ‘Report’

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Energy Yield Estimation PVSYST Design Report

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Energy Yield Estimation PVSYST Design Report

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Energy Yield Estimation PVSYST Design Report

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THANK YOU

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PHOTOVOLTAIC (PV) – INSTALLER GUIDE

© 2011 Underwriters Laboratories Inc.

Objective

• • •

Verify System Design Managing the project Installing electrical components

• • •

Installing Mechanical components Completing system Installations Conduction system maintenance & Troubleshooting Activity.

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1

Introduction Balance of system (BOS) component include all mechanical of electrical equipment and hardware used to assemble and integrate the major components in a PV system Example of BOS components include:

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Types of systems

4

2

Verify system Design •

Determine Clients Need

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3

Review Site Survey •

Obtaining the necessary information during a site survey helps plan and execute PV installations in a timely and cost effective manner.

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Tools Used During Site Survey

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4

Array Location 2. Is it shaded? 3.Is the structure strong enough? 4. How will the array be mounted?

5. How far the array will be mounted from other equipments? 1.

Enough Area to get maximized energy

9

Array Location

Will the array be s ubjected

to damage or accessible to unqualified person?

Are there any local codes or wind load concerns for areas of PV installation? Are there additional safety, installation or maintenance concern?

How will the array be installed & maintained?

10

5

Array Area 

For multiple rows of tilted racks or for tracker installation additional spacing is required between each array mounting structure to prevent the row to row shading.



Additional area is required for installation of other equipments. Usually for 1 KW dc crystalline power plant we need approximately 80 to 100 sf of surface area. As a thumb rule we can say that for 1 KW power plant approximately 16 square meter area is required.



11

Perform a shading analysis • •

PV array should be unshaded at least 6 hours during the middle of the day to produce the maximum energy possible. Ideally there should be no shadow between 9 a.m. and 3 p.m. solar time over the year, since the majority of solar radiation and peak system output occur during this period.

12

6

Sun Path finder

13

Array mounting method. •

PV array can be mounted on the ground, rooftops and other structures that provide adequate protection, support and solar access. The site conditions and Results of the site survey usually distance the best mounting system location and approach to use.

14

7

Array mounting systems

Building integrated Mounting System

15

Roof Structure and conditions Key points: 1. Check out the roof’s load bearing capacity and its underlying structures so that it can bear the additional load. 2. A civil engineer need to calculate the load with respect to local code compliance. We can also refer to standard ASCE 7 – minimum loads for buildings and other structures. 3. A standard roof mounting structure weighs between 3 and 5 pounds per square feet which is fine for most roofs designed to recent standards. 4. A span table can help to quantify the load bearing capabilities of roof trusses or beams. The website for this is www.solarabcs.org. 16

8

Roof Structure and conditions 1.

Wind loads are the primary concern for roof top m ounting systems. For hurricane prone regions the design wind load can be as high as 150 m ph w hich can exceed the actual wind load of 50 PSF and m ore in some corners of roof or structure. A structure engineer is required for the approval of the structures w ith respect to the wind load design of the array.

2.

Before deciding the PV array mounting system verify with the m ounting system supplier that the hardware is appropriate for the given application.

3.

For com m ercial roof m ounting system we can use the ballasted mounting system. This is significantly heavier than mounting system designed for direct structural attachments. But this system needs special load calculation. The m ain advantage is the possibility of roof leaks is greatly diminished.

17

BOS Location 1. 2. 3.

4. 5.

Selection of appropriate location for all the BOS. The BOS have to e w eather resistant. They may need to be installed in the w eather resistant enclosures. For this w e can refer to article 110 from NEC. Avoid installing electrical equipments in locations exposed to high tem perature and direct sunlight and provide adequate ventilation and cooling for heat generating equipments like inverters, generators, charge controllers etc. It is always better to have proper IP rating for these equipments to avoid damage from rain, dust, chemical and other environmental factors. Battery location should be protected from extreme cold area because this will reduce the available capacity. They should be installed as per NEC 480. Protection should be taken to prevent the attack from insects, rodents and other debris.

18

9

Confirm System Sizing : Size module mounting Area •

If site is selected for array location, it is necessary to determine whether the place is enough for the proposed number of PV modules.

•

For Areas with NON-rectangular shapes, determine the amount of usable area can be challenged.

•

Access to the modules must be provided in case system maintenance is needed.

•

Smaller array surface area are required to generate the same amount of power with higher efficiency modules.

19

Confirm System Sizing : Arrange Modules in mounting area •

S itting the PV array in the available Mounting area can have a large impact on the performance of a PV array. • Each set of modules in a series string must be oriented in the same direction if the string is to produce its full output potential. • Is it possible to split a string between two roof faces, provided the modules keep the exact same orientation EXAMPLE :

20

10

21

Confirm System Sizing :Review Energy Storage Systems • • •

•

Capacity is a measure of battery energy storage, commonly rated in Ampere-hour Rate of charge or discharge is expressed as a ratio of the nominal battery capacity to the charge of discharge time period in hours. Usable capacity is always less than the rated battery capacity. Operational factors that effect available battery capacity include discharge rate, cut-off voltage, temperature and Age of battery A nominal 100 Ah battery discharged at 5 amps for 20 hours is considered a C/20, or 20 hour discharge rate

22

11

Confirm System Sizing :Review Energy Storage Systems • The battery state of charge is related to the concentration of sulfuric acid concentration. This is measured by specific gravity. • Specific gravity is the ratio of the density of a solution to the density of water. • A fully charged lead acid cell has a typical specific gravity between 1.26 and 1.28 at room temperature. • The specific gravity may be increased for lead-acid battery used in cold weather applications. Conversely, the specific gravity can be decreased for application in warm climate.

• In very cold climate the battery should be protected from freezing by limiting minimum temperature in a suitable enclosure or by limiting the Depth of Discharge.

23

Confirm System Sizing :Review Energy Storage Systems Depending on the application or site requirement many factors are considered to select the battery and for system design as follows: • • • • • • •

Electrical properties: voltage, capacity, charge/discharge rates Performance: cycle life vs. DOD, system autonomy Physical properties: size and weight Maintenance requirements: flooded or VRLA Installation: Location, structural requirements, environmental conditions Safety and auxiliary systems: racks, trays, fire protection, electrical BOS Costs, warranty and availability.

24

12

Confirm System Sizing: Review Energy Storage System Installation: location, structural requirements, environmental conditions

Electrical Properties: voltage, capacity, charge/discharge rates

Performance: cycle life Vs. DOD, system autonomy

Costs, w arranty and availability

Physical properties: Size and weight

Maintenance requirements: Flooded or VRLA

Safety and auxiliary systems: racks, trays, fire protection, electrical BOS 25

Confirm System Sizing :Review Energy Storage Systems •

Racks and trays are used to support battery systems and provide electrolyte containment

•

Racks can be made from metal, Fiberglass or other structural non conductive material.

•

Metal racks must be painted.

•

Due to potential for ground faults, metals or other conductive battery tracks are not allow ed for open Vent flooded lead acid batteries more than 48 Volts nominal.

•

If batteries are connected in series to produce more than 48 V, then the batteries must be connected in a manner that allow s the series strings of batteries to be separated into strings of 48 V or less for maintenance.

•

Overcurrent protection device or other such protective equipment's should be installed on the battery side to protect battery from fault currents.

26

13

Charge controller operations • • • • •

A battery charge controller limits the Voltage and current delivered to battery from a charging source to regulate state-of-charge. A CC is required in most PV systems that use battery storage. PV array must not be capable of generating voltage or current that will exceed the CC input voltage & current The CC rated continuous current must be 125% of the PV array Shot circuit O/p current. The CC maximum i/p voltage should be greater than the maximum system voltage

27

Charge controller operations : Set points Set Point: Set points are the battery voltage levels at w hich a charge controller performs regulation or control functions. The [proper regulation set points are critical for optim al battery charging. Load Inverter

Charge controller

1. Regulation Voltage (VR)

is the maximum v oltage set point the controller allows the battery to reach bef ore the array current is disconnected or limited.

2. The array Reconnect Voltage (ARV) – f or interrupting ty pe controllers, is the v oltage set point at which the array is reconnected to charge the battery Battery Bank

3. Low Voltage Disconnect (LVD) – def ines the maximum battery depth of discharge at the giv en discharge rate.

For a ty pical lead acid cell a LVD set point of 1.85 VPC to 1.91 VPC corresponds to a DOD of 70 to 80% at C/20 discharge rates or lower.

4. Load Reconnect Voltage (LRV)- the set point where load are reconnected to battery. A higher LRV allows a battery to receiv e more charge bef ore loads are reconnected to the battery.

28

14

Charge controller operations : PWM VS Advance CC

:

29

Charge controller operations • •

• • • •

The temperature Compensation is a feature of CC that automatically adjusts charge regulation voltage for battery temperature changes. The sensors can be internal or may be fixed to batteries.

Temperature compensation is recommended for all types of sealed batteries, which are more sensitive to overcharging than flooded type. Temperature compensation Helps to fully charge a battery during colder conditions, and helps protect it from Overcharge and Over discharge. For larger systems, the O/p of multiple CC may be connected in parallel and used to charge a single battery bank. A diversionary CC diverts excess PV array power to Auxiliary loads when primary battery is fully charges.

30

15

Maximum power point tracking (MPPT) •

A MPPT Charge controller operates PV arrays at Maximum power under all operating conditions independent of battery voltage.

•

MPPT can improve array utilization and allow non-stnadard and higher array operating voltages, requiring smaller conductors and fewer source circuit to charge lower voltage battery bank.

•

Normally the O/p current of a MPPT will be less than or equal to the I/p Current.

•

If a MPPT CCU is used it is important to consult the Manufacturer’s spec to determine the Maximum O/p load.

31

Series connections

32

16

Parallel connections

33

PV Inverter Stand Alone inverter: operates from battery and supply power independent of the electrical utility system. They may also include battery charger to operate from an independent AC source such as generator.

Bi-m odal inverter: battery based interactive inverter acts as diversionary charge controllers by producing AC power o/p to regulate PV array battery charging and sends excess power to the grid when energized. .

34

17

PV Inverter Utility-interactive or grid connected inverter: operates from PV arrays an supply pow er in parallel w ith an electrical production and distribution network.

Types: 1. Module level inverter: They include AC modules and micro inverters. They are sm all and rated for 200 to 300W m aximum. Advantages of these inverters are, they include individual m odule MPPT and better energy harvest from partially shaded and m ulti directional arrays. More safer than string inverters as the m axim um dc voltage on array is for a single module (35 -60V). 2. String Inverter: small inverters in the 1 KW to 12 KW size range, intended for residential and small commercial applications. Generally single phase and lim ited to 1 to 6 parallel connected source circuits. 35

Different types of Grid interactive inverters.

Central inverter – 30 kW to 1 MW

36

18

Specification of inverters

37

Inverter Standards

38

19

Review Wiring and conduit size calculations Determine circuit current :

PV Power S ource Maximum circuit current :

Inverter output circuit current :

39

Calculate required ampacity of the conductor (Wire) The required ampacity of conductors is based on : • Maximum Circuit current • Size of overcurrent protection device • Ambient temperature of the conductor • Type of conductor and insulation • The conduit fill of the conductor

40

20

41

42

21

43

44

22

Calculate Voltage Drop

45

Link to calculate the voltage drop: http://www.csgnetwork.com/voltagedropcalc.html 46

23

47

Personal protective equipment's

48

24

Install Wiring systems  



PV string cables, PV array cables and PV DC main cables shall be selected and erected so as to minimize the risk of earth faults and shortcircuits. Wire Management: Array conductors are neatly and professionally held in place

Wiring systems shall withstand the expected external influences such as wind, ice formation, temperature and solar radiation.

49

Install Wiring systems 

Protection by use of class II or equivalent insulation should preferably be adopted on the DC side.

Common Installation Mistakes with Wire Management: 1. Not enough supports to properly control cable. 2. Conductors touching roof or other abrasive surfaces exposing them to physical damage. 3. Conductors not supported within 12 inches of boxes or fittings. 4. Not supporting raceways at proper intervals. 5. Multiple cables entering a single conductor cable gland (aka cord grip) 5. Pulling cable ties too tight or leaving them too loose. 6. Bending conductors too close to connectors. 7. Bending cable tighter than allowable bending radius. 8. Plug connectors on non--‐locking connectors not fully engaged 50

25

Install Grounding system

51

Utility Interconnection

52

26

Installing Mechanical Components

53

CIVIL CONSTRUCTIONS

54

27

Install PV modules

55

Selection of Modules

56

28

Install PV modules

57

Commission of systems

58

29

Visual Inspection

59

Test the System

60

30

THANK YOU.

31

IEC 62446: Grid Connected Photo Voltaic Systems – Minimum Requirements for System Documentation, Commissioning Tests and Inspection

© 2011 Underwriters Laboratories Inc.

Learning Objective

.

To verify the safe installation and correct operation of grid connected solar Power plants

documentation

commissioning tests

inspection criteria

2

1

Content Clause 4: System documentation requirements Clause 4.2: System Data Clause 4.3: Wiring diagram Clause 4.4: Datasheets Clause 4.5: Mechanical design information Clause 4.6: Operation and maintenance information Clause 4.7: Test results and commissioning data Clause 5 :Verification Clause 5.2:Inspection Clause 5.2: Testing Clause 5.2: Verification reports

3

Clause 4: System documentation requirements

© 2011 Underwriters Laboratories Inc.

2

5

4.2 System data - Basic system information Project identification reference (where applicable). Rated system power (kW DC or kVA AC). PV modules and inverters - manufacturer, model and quantity.

Installation date. model and quantity. PV modules and inverters - manufacturer, Commissioning date.

Customer name. Site address.

6

3

4.2.2 System designer information Information shall be provided for all bodies responsible for the design of the system. Where more than one company has responsibility for the design of the system, information's together with a description of their role in the project.

System designer, postal address, telephone number and email address.

System designer, company.

System designer, contact person.

7

4.2.3 System installer information Information shall be provided for all bodies responsible for the installation of the system. Where more than one company has responsibility for the installation of the system, information should be provided for all companies together with a description of their role in the project.

System installer, postal address, telephone number and email address.

System installer, company

System installer, contact person.

8

4

4.3 Wiring diagram

Array - general specifications

Array electrical details

PV string information

a) Array main cable specifications – size and type. a) Module type(s) b) T otal number of modules

a) String cable specifications – size and type.

c) Number of strings

b) String overcurrent protective device specifications

d) Modules per string

c) Blocking diode type (if relevant).

b) Array junction box locations

c) DC isolator type, location and rating d)

Array overcurrent protective devices – type, location and rating (voltage / current).

Earthing and overvoltage protection

a) Details of all earth / bonding conductors b) Details of any connections to an existing Lightning Protection System (LPS). c)

Details of any surge protection device installed (both on AC and DC lines) to include location, type and rating.

AC system

a) AC isolator location, type and rating. b)

AC overcurrent protective device location, type and rating.

c)

Residual current device location, type and rating (where fitted).

9

10

5

4.4 Datasheets Datasheets shall be provided for the following system components NOTE The provision of datasheets for other significant system components should also be considered.

Module datasheet for all types of modules used in the system - to the requirements of IEC 61730-1.

Inverter datasheet for all types of inverters used in the system.

11

4.5 Mechanical design information A data sheet for the array mounting system shall be provided.

12

6

4.6 Operation and maintenance information Operation and maintenance information shall be provided and shall include, as a minimum, the following items: Procedures f or v erif ying correct sy stem operation.

A checklist of what to do in case of a sy stem

Emergency shutdown / isolation procedures

Maintenance and cleaning recommendat ions (if any).

f ailure. Considerations for any future building works related to the PV array (e.g. roof works).

Warranty documentation for PV modules and inverters - to include starting date of warranty and period of warranty.

Warranty Documentation on any applicable workmanship or weather-tightness warranties.

13

Clause 5 : Verification

© 2011 Underwriters Laboratories Inc.

7

5.3 Inspection (Requirements)

 PV array design and installation  PV system - protection against overvoltage / electric shock  PV system - AC circuit special considerations  PV system - labelling and identification  PV system - general installation (mechanical)

15

PV array design and installation.

© 2011 Underwriters Laboratories Inc.

8

Stand Alone SPV power Plant

17

Grid Connected SPV power plant

18

9

Field Inspection Checklist for Array:

1.

2.

Number of PV modules and model number matches plans and spec sheets with the module model number and quantity of modules confirmed, the physical layout of the array should match the supplied site plan.

Common Installation Mistakes with Array Modules and Configurations:

1. Changing the array wiring layout without changing the submitted electrical diagram. 2. Changing the module type or manufacturer as a result of supply issues. 3. Exceeding the inverter or module voltage due to improper array design. 4. Putting too few modules in series for proper operation of the inverter during high summer array temperatures .

19

Ratings for DC Components •

DC components rated for current and voltage maxima (Voc stc corrected for local temperature range and module type; current at Isc @ stc × 1.25

Note: 1) Overload protection may be omitted to PV string and PV array cables when the continuous current-carrying capacity of the cable is equal to or greater than 1,25 times ISC STC at any location. 2) Overload protection may be omitted to the PV main cable if the continuous current-carrying capacity is equal to or greater than 1,25 times ISC STC of the PV generator.

20

10

Array Junction Box/ Main Junction Box/Combiner Box

DC Disconnect device

Surge Protector

Fuse

(L+ & L-) going to inverter

Incoming String Wires

21

Wiring systems  



PV string cables, PV array cables and PV DC main cables shall be selected and erected so as to minimize the risk of earth faults and shortcircuits. Wire Management: Array conductors are neatly and professionally held in place

Wiring systems shall withstand the expected external influences such as wind, ice formation, temperature and solar radiation.

22

11

DC Cables. 

Protection by use of class II or equivalent insulation should preferably be adopted on the DC side.

Common Installation Mistakes with Wire Management: 1. Not enough supports to properly control cable. 2. Conductors touching roof or other abrasive surfaces exposing them to physical damage. 3. Conductors not supported within 12 inches of boxes or fittings. 4. Not supporting raceways at proper intervals. 5. Multiple cables entering a single conductor cable gland (aka cord grip) 5. Pulling cable ties too tight or leaving them too loose. 6. Bending conductors too close to connectors. 7. Bending cable tighter than allowable bending radius. 8. Plug connectors on non--‐locking connectors not fully engaged 23

DC Conductors earthing.  Earthing of one of the live conductors of the DC side is permitted, but there must be a simple separation between the AC side and DC side.

24

12

DC switch disconnector  In every PV installation it is necessary to isolate the photovoltaic panel from the rest of the system.  DC Isolators must have a higher performance than the traditional AC Isolators because breaking direct current is more difficult than breaking alternating current.  DC switch disconnector should be fitted to the DC side of the inverter.

415V, 63A, 3pole AC MCB 25

Example to calculate the disconnect devices •

Example of PV sizing of disconnect switches.

Determine the minimum size in terms of Voltage and current of the disconnect based on follow ing informations: Maximum input operating range : 300 -480 V dc Maximum input voltage (Voc) :

600V

Maximum rated input current :

800A (DC)

Maximum input Isc rating

:

Maximum rated output current :

1200 A (DC) 300 A (AC)

26

13

Example to calculate the disconnect devices Solution :

• PV Disconnect Maximum continuous input current = maximum input short circuit current rating * 125% = 1200A * 125% = 1500A (DC) Maximum input Voltage (Voc) = 600 V (DC)

 The PV disconnect switch must be rated for minimum of 1500A(dc) @ 600 V (dc).  PV disconnect devices for 1000Vdc shall be evaluated under UL98B.

27

Blocking diodes.

 If blocking diodes are used, their reverse voltage should be rated for 2 × Voc STC of the PV string.

 The blocking diodes shall be connected in series with the PV strings.

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14

PV system - protection against overvoltage / electric shock

© 2011 Underwriters Laboratories Inc.

RCD’s

 If the PV inverter is without at least simple separation between the AC side and the DC side, the RCD installed has to be of type B.

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15

Type B residual current device.

Residual current device for which tripping is ensured:  for residual sinusoidal alternating currents up to 1000 Hz.  for residual alternating currents superimposed on a smooth direct current of 0.4 times the rated residual current.  for residual direct currents which may result from rectifying circuits.  for residual smooth direct currents.

31

Protection against electromagnetic interference.  The area of all wiring loops shall be as small as possible, to minimize voltages induced by lightning.

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Lightning.  In the event of a lightning strike or surge the surge arrestor conducts the charge bleeding it out of the circuit to ground.  Each LIGHTNING ARRESTER shall be earthed through suitable size earth bus bar with earth pits.

33

PV system - AC circuit special considerations.

© 2011 Underwriters Laboratories Inc.

17

AC circuit special considerations.  Means of isolating the inverter should be provided on the AC side.  Inverter protection settings should be programmed to local regulations.

36

AC circuit special considerations.  In the selection and erection of devices for isolation and switching to be installed between the PV installation and the public supply, the public supply should be considered as the source and the PV installation shall be considered the load.  To allow maintenance of the PV inverter, means of isolating the PV inverter from the DC side and the AC side shall be provided.

37

18

labelling and identification

© 2011 Underwriters Laboratories Inc.

Labelling.

 All circuits, protective devices, switches and terminals are suitably labelled.  All DC junction boxes (PV generator and PV array boxes) carry a warning label indicating that active parts inside the boxes are fed from a PV array and may still be live after isolation from the PV inverter and public supply. 39

19

Labelling.  Main AC isolator are clearly labelled.  Dual supply warning labels are fitted at point of interconnection.

 Single line wiring diagram is displayed on site.  Inverter protection settings and installer details are displayed on site.  Emergency shutdown procedures are displayed on site.

40

PV system - general installation (mechanical)

 Ventilation has to be provided behind array to prevent overheating / fire risk.

41

20

General installation (mechanical)  Array frame and material has to be corrosion resistant.  Array frame has to be correctly fixed and stable and roof fixings should be weatherproof.

42

Cable entry has to be weatherproof.

 All Cable entry shall be thoroughly sealed and made waterproof with UV-resistant silicone sealant or equivalent .

 Cables through roofing shall be contained in roof-entry boxes, which also shall form a waterproof seal to avoid leakage.

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21

Testing : PV array

© 2011 Underwriters Laboratories Inc.

Parameters of testing

1. 2.

polarity test string open circuit voltage test

3. 4. 5. 6.

string short circuit current test functional tests insulation resistance of the DC circuits continuity of protective earthing and/or equipotential bonding conductors

45

22

polarity test

 The polarity of all DC cables shall be verified using suitable test apparatus. Once polarity is confirmed, cables shall be checked to ensure they are correctly identified and correctly connected into system devices such as switching devices or inverters.

46

Array Parameters – Voc & Isc PV string - open circuit voltage measurement • The open circuit voltage of each PV string should be measured using suitable measuring apparatus. This should be done before closing any switches or installing string over-current protective devices (where fitted). • Measured values should be compared with the expected value. Comparison to expected values is intended as a check for correct installation, not as a measure of module or array performance. • For systems with multiple identical strings and where there is stable irradiance conditions, voltages between strings shall be compared. These values should be the same (typically within 5 % for stable irradiance conditions). For non stable irradiance conditions, the following methods can be adopted: • testing may be delayed • tests can be done using multiple meters, with one meter on a reference string • an irradiance meter reading may be used to adjust the current readings. 47

23

PV string - current measurement •

Like the open circuit voltage measurements the purpose of a PV string current measurement test is to verify that there are no major faults within the PV array wiring. These tests are not to be taken as a measure of module / array performance. • Two tests methods are possible and both will provide information on string performance. Where possible the short circuit test is preferred as it will exclude any influence from the inverters. a) PV string – short circuit test b) PV string – operational test

48

PV string – short circuit test procedure •

Ensure that all PV strings are isolated from each other and that all switching devices and disconnecting means are open. • A temporary short circuit shall be introduced into the string under test. This can be achieved by either: a) A short circuit cable temporarily connected into a load break switching device already present in the string circuit. b) The use of a “short circuit switch test box” – a load break rated device that can be temporarily introduced into the circuit to create a switched short circuit. In either case the switching device and short circuit conductor shall be rated greater than the potential short circuit current and open circuit voltage. The short circuit current can then be measured using either a clip on ammeter or by an in-line ammeter

49

24

PV string – operational test procedure •

•

•

With the system switched on and in normal operation mode (inverters maximum power point tracking) the current from each PV string should be measured using a suitable clip on ammeter placed around the string cable. Measured values should be compared with the expected value. For systems with multiple identical strings and where there are stable irradiance conditions, measurements of currents in individual strings shall be compared. These values should be the same (typically within 5 % for stable irradiance conditions). For non-stable irradiance conditions, the following methods can be adopted:

a) testing may be delayed b) tests can be done using multiple meters, with one meter on a reference string c) an irradiance meter reading may be used to adjust the current readings. 50

Array insulation resistance - Precautions PV array DC circuits are live during daylight and, unlike a conventional AC circuit, cannot be isolated before performing this test. Performing this test presents a potential electric shock hazard, it is important to fully understand the procedure before starting any work. It is recommended that the following basic safety measures are followed: • Limit the access to the working area. • Do not touch and take measures to prevent any other persons to touch any metallic surface with any part of your body when performing the insulation test. • Do not touch and take measures to prevent any other persons from touching the back of the module/laminate or the module/laminate terminals with any part of your body when performing the insulation test. • Whenever the insulation test device is energized there is voltage on the testing area. The equipment is to have automatic auto-discharge capability.

51

25

PV array insulation resistance test - test method The test should be repeated for each PV array as a minimum. It is also possible to test individual strings if required. Two test methods are possible: TEST METHOD 1 - Test between array negative and earth followed by a test between array Positive and Earth. TEST METHOD 2 - Test between earth and short circuited array positive and negative.

52

PV array insulation resistance test - test method •

Where the structure/frame is bonded to earth, the earth connection may be to any suitable earth connection or to the array frame (where the array frame is utilized, ensure a good contact and that there is continuity over the whole metallic frame).

•

For systems where the array frame is not bonded to earth (e.g. where there is a class II installation) a commissioning engineer may choose to do two tests: a) between array cables and earth and an additional test b) between array cables and frame.

•

For arrays that have no accessible conductive parts (e.g. PV roof tiles) the test shall be between array cables and the building earth.

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PV array insulation resistance test - test method •

Before commencing with the test: limit access to non-authorized personnel; isolate the PV array from the inverter (typically at the array switch disconnector); and disconnect any piece of equipment that could have an impact on the insulation measurement (i.e. overvoltage protection) in the junction or combiner boxes.

•

Where a short circuit switch box is being used to test to method 2, the array cables should be securely connected into the short circuit device before the short circuit switch is activated.

•

The insulation resistance test device shall be connected between earth and the array cable(s) as appropriate to the test method adopted. Test leads should be made secure before carrying out the test. Follow the insulation resistance test device instructions to ensure the test voltage is according to Table 1 and readings in MΩ. The insulation resistance, measured with the test voltage indicated in Table 1, is satisfactory if each circuit has an insulation resistance not less than the appropriate value given in Table 1.

•

•

Ensure the system is de-energized before removing test cables or touching any conductive parts. 54

PV array insulation resistance test - test method

55

27

5.4.2 Continuity of protective earthing and/or equipotential bonding conductors

PV

PV

PV

PV

PV

Power

Apply current = 2.5 X fuse rating Supply Fuse rating = 1.35 X Isc For example if the string have current of 8A, the fuse rating w ill be 10.8A =15A Apply current = 2.5 X 15 = 37.5 A

56

5.4.6 Functional tests

The following functional tests shall be performed: a) Switchgear and other control apparatus shall be tested to ensure correct operation and that they are properly mounted and connected. b) All inverters forming part of the PV system shall be tested to ensure correct operation. The test procedure should be the procedure defined by the inverter manufacturer.

c) A loss of mains test shall be performed: With the system operating, the main AC isolator shall be opened – it should be observed (e.g. on a display meter) that the PV system immediately ceases to generate. Following this, the AC isolator should be re-closed and it should be observed that the system reverts to normal operation.

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THANK YOU.

29

Shadow affect on PV panels.

© 2011 Underwriters Laboratories Inc.

INTRODUCTION

The choice of a proper location is the first and the very essential step in solar system design procedure. The m odules have to be fixed w ith proper tilt angle and distance to prevent Shadow on the m odule for efficient operation.

© 2011 Underwriters Laboratories Inc.

1

Sun

•

The sun is a gaseous body composed mostly of hydrogen.

•

Gravity causes intense pressure and heat at the core initiating nuclear fusing reactions.

•

Even when planet Earth is 93 million miles away, we still receive an amazing quantity of usable energy from the sun.

3

Solar energy in India.

 Today, more than 40% of the Indian population, or approximately 1,25,000 villages, have no access to reliable electricity.

 If 1.25% of Indian Land is used to harness Solar energy, It would yield 8 million Mega watt.  It is equivalent to 5909 mtoe(million tons of oil equivalent) per year.

4

2

Solar Radiation Spectrum

5

Solar Radiation

•

Solar irradiance is the intensity of solar power, usually expressed in Watts per square meter [W/m^2]

•

Since the proportion of input/output holds pretty much linearly for any given PV efficiency, we can very easily evaluate a system performance by measuring irradiance and the PV module output.

•

Solar spectral distribution is important to understanding how the PV modules respond to it.

•

Most Silicon based PV devices respond only to visible and the near infrared portions of the spectrum.

•

Thin film modules generally have a narrower response range.

6

3

Solar Intensity on Planets.

7

Solar Radiation

www.cab rillo.edu/.../Chapter%202%20Solar%20Radiation

4

Basics of Directions & Angles.

Coordinate systems : • Earth based – latitude and longitude. • Observer based – azimuth angle and altitude angle.

Latitude Latitude lines run east/west but they measure north or south of the equator (0°) splitting the earth into the Northern Hemisphere and Southern Hemisphere.

5

Latitude

Lines of latitude are numbered from 0° at the equator to 90° at the North Pole.

North Pole 90

80 70

[

60 50 40 30 20 10

]

10 20 40

5030 60 70

South90Pole

180°

80

Longitude

East Longitude

West Longitude

North Pole

Lines of latitude are numbered from 0° at the equator to 90° at the South Pole.

N

W

PRIME MERIDIAN

E

S

The prime meridian is the vertical line that marks the zero degree longitude measurement on the globe of Earth. Lines of longitude are numbered east from the Prime Meridian to the 180° line and west from the Prime Meridian to the 180° line.

6

True South In the Northern Hemisphere, stationary PV arrays are oriented south to maximize PV output. But using your compass to find south will only give you an indication of magnetic south, not True South.

. The difference in the orientation is called as magnetic declination.

13

True North

 In the Southern Hemisphere, stationary PV arrays are oriented north to maximize PV output. But using your compass to find north will only give you an indication of magnetic north, not True North.

 Usually the magnetic declination should be either subtracted or added to your magnetic compass reading to find True North or True south. The declination is based on your latitude and longitude. The follow ing link can be used to find the magnetic declination at any place. http://magnetic-declination.com/ 14

7

Altitude-Azimuth coordinate system Based on what an observer sees in the sky. Zenith = point directly above the observer (90o) Nadir = point directly below the observer (-90o) – can’t be seen Horizon = plane (0o) Altitude = angle above the horizon to an object (star, sun, etc) (range = 0o to 90o)

Note: lines of azimuth converge at zenith

Zenith angle. • Zenith is the point in the sky directly overhead a particular location –as the Zenith angle Өz increases, the sun approaches the horizon.

8

Solar Radiation • Array orientation is defined by two angles: Tilt angle is the vertical angle between the horizontal and the array surface

www.cab rillo.edu/.../Chapter%202%20Solar%20Radiation

Altitude and Azimuth angle.

 Solar Altitude Angle is the vertical angle between the sun and the horizon –added to the Zenith angle is equal to 90º.  Azimuth Angle is the horizontal angle between a reference direction. In the solar industry we call south 180º and this angle will range between 90º (east) and 270º (west).

9

Array Azimuth Angle. Array Azimuth Angle is the horizontal angle between a reference direction – typically south - and the direction an array surface faces.

Solar Declination. • Solar Declination is the angle between the equatorial plane and the ecliptic plane • The solar declination angle varies with the season of the year, and ranges between –23.5º and +23.5º

10

Solstices. Summer Solstice is at maximum solar declination (+23.5º) and occurs around June 21st –Sun is at Zenith at solar noon at locations 23.5º N latitude. Winter Solstice is at minimum solar declination (-23.5º) and occurs around December 21st At any location in the Northern Hemisphere, the sun is 47º lower in the sky at noon on winter solstice than on the summer solstice – Days are significantly shorter than nights.

Sun path

 Sun path refers to the apparent significant seasonal-and-hourly positional changes of the sun as the Earth rotates, and orbits around the sun.

 Sun path helps us to find, Azimuth angle and Altitude angle For particular place at specific Time of the day.

22

11

Steps to find Azimuth angle and Altitude angle. For a certain location, for a certain day and hour, azimuth and altitude angles may be defined by the following procedure. For this purpose the sun path diagram prepared for that location should be used. Example : Define the position of the sun in Bangalore at 9:00 am of December 21.

Step 1:

Select the sun path diagram for the site latitude (or nearest latitude). For Bangalore 12˚58’ North latitude may be selected.

Step 2: Step 3:

Find the date curve for December 21. Find the hour line for 9:00 am and mark its intersection with the curve of December 21.

Step 4:

Lay a straight-edge from the center of the chart from the observation point) through the marked hour point to the perimeter circle. Read the Azimuth Angle from the perimeter scale. For this example (α) = 127˚.

Step 5:

On he straight line, measure the distance in millimeter between the perimeter circle and the marked point. Each millimeter represents one degree of altitude angle. This distance will be measured 28.5 mm. This means the altitude of the sun at 9:00 am of December 21 in Bangalore is (θ) = 28.5˚.

23

SUN path for Bangalore.

24

12

Hourly Sun Path

25

Annual Sun Path

26

13

The main aspect to study are

• • •

Tilt of the solar panel. Shadows of extern elements. Shadows of own elements.

27

Edge shadowing. Edge shadowing which may happen in PV field due to dust accumulated on the tilted PV array. This happens intensively in the bottom edges of the panels causing another type of reduction of the PV output.

Edge shading is also possible to happen in field due to the shadows cast by other PV cells and the tilt, the orientation and the surface temperature variation of the PV panel.

Shading of one region of a module compared to another leads to mismatch is PV modules. 28

14

Tilt angles

•

The optimum tilt angle of the solar panel can be expressed by the following simplified formula: Tilt = Latitude

•

Tilt angles below 15º in urban areas may cause system losses due to pollution and dirt accumulation on the panels.

•

Local land slope will be logically taken into account, which can help reducing distance between the panel rows to improve the surface profit.

29

Another tilt angles table. Bangalore Optimum Tilt of Solar Panels by Month Jan

Feb

Mar

Apr

May

Jun

61°

69°

77°

85°

93°

100°

Jul 93°

Aug 85°

Sep 77°

Oct 69°

Nov 61°

Dec 54°

W inter

54° angle

Winter

Spring/Autu mn 77° angle Spring/Autumn

Summer

100° angle

Summer

Figures shown in degrees from vertical 54° angle

77° angle

100° angle 30

http://solarelectricityhandbook.com/solar-angle-calculator.html

15

Orientation angle

• The most favorable orientation is 180º South (North hemisphere).

• For Southern hemisphere 0º North. • An orientation deviation below 20º (East or West) cause negligible system losses.

31

Distance between panel rows

 A basic rule would be to avoid shadows during the 6 – 8 central hours of the day, in the day of the year with less radiation.

 This implies calculating the angle of the sun (height regarding the line of the horizon) to +/- 3 - 4 hours regarding the solar midday. This angle will vary depending on the latitude.

 The objective is to avoid that the top of the front panel projects a shadow to the lowest part of the panel that is placed behind.

32

16

Distance between the panels.

D = Sin(a + Θ )

*

H

Sina (Θ) The variable is the tilt of the panels. (H) The height of the panel. (α) is a function of the latitude of the installation and the optimal sun elevation. (D) is the distance between the panels.

33

Minimum space between the panels.

 Space between two rows of solar structures should be atleast twice of the height of the solar panel structures at the highest point of tilt. This minimum space is required to avoid shadow of one row of solar structure to fall on the row behind it.  Similarly if there is an obstacle, on the southern side of the solar structure/modules the distance of the solar structure/module facing the obstruction should be atleast twice the height of the obstruction. 34

17

Hot-Spot Heating

•Hot-spot heating occurs when there is one low current solar cell in a string of at least several high short-circuit current solar cells.

•

One shaded cell in a string reduces the current through the good cells, causing the good cells to produce higher voltages that can often reverse bias the bad cell.

•

Power gets dissipated in the “poor” cell. 35

Hot spot effects



Local overheating, or "hot-spots", leads to destructive effects cell or glass cracking, melting of solder or degradation of the solar cell.

36

18

Bypass Diodes  One by pass diode per solar cell is too expensive option.  Amount mismatch depends on the degree of shading.  A partial shading will cause a lower forward bias voltage.

 The maximum group size per diode, without causing damage, is about 15 cells/bypass diode, for silicon cells.  Normally for 36 cell module 2 bypass diodes are used. 37

THANK YOU.

19

Grounding and Bonding in Photovoltaic Installations

© 2011 Underwriters Laboratories Inc.

Grounding • Grounding is the process of connecting a system, equipment or both to the earth.

2

1

Bonding • Bonding is the process of connecting to conductive objects together.

• Grounding and bonding means that conductive parts are connected together and to the earth. 3

Grounding Faults

4

2

Grounding and Bonding •

PV Modules Array and Frames

•

Inverter

•

Switchgear and Panels

•

Transformers

One hardware in one Grounding hole Not to be shared with Mounting holes

5

Grounding and Bonding in PV Modules

6

3

Grounding and Bonding in PV Modules Grounding hardware knowhow: •

Type of metal

Aluminum, Copper or Stainless Steel

•

Type of Screw

Thread Cutting or provided with Nut

•

Nut Bolt Combination

Washer types

7

Grounding and Bonding in Inverters

8

4

Grounding and Bonding in Enclosures

9

Grounding in Transformers

10

5

Grounding of Grid connected PV System

11

Grounding of Roof Mounted PV System

12

6

Grounding and Bonding Grounding hardware

13

Grounding and Bonding in PV Modules Bolts and screws

14

7

Grounding and Bonding in PV Modules Tightening Torque in N-m – Indicative Values Slotted head screw Wire size

Upto 4 m m 2

Slot w idth – max 1.2 mm and slot length max 6.4 mm

Slot w idth – over Hexagonal 1.2 mm and slot head length over 6.4 mm

2.3

4.0

8.5

Recessed Allen or Square drive Socket width across flats in m m Torque (Nm) 3.2 5.1 4.0 11.3 4.8 13.6 5.6 16.9 6.4 22.6 7.9 31.1 9.5 42.4 12.7 56.5 14.3 67.8

15

Electrochemical Potential

Copper

Tin plated Copper

Aluminum

Stainless Steel

16

8

Electrochemical Potential

17

Electrochemical Potential Stainless steel with Aluminum with slight trace of chloride in the environment

18

9

Dissimilar Metal Combination – Electrochemical Potential

19

Do you see any issue here ??

20

10

…and here ??

21

…and here ??

22

11

…finally here ??

23

Grounding IS 3043 – Code of Practice for Earthing Applicable for Land Based installations Important considerations: •

Soil Resistivity

Depends upon Climate

•

No natural Drainage

..but no water flowing over it

•

Artificial Treatment

NaCl, CaCl, Na2CO3, CuCO4, Soft Coke, Charcoal

•

Shape of Electrode

Plate, Rods, Pipe

24

12

Grounding Soil Resistivity Function of soil moisture and the concentrations of ionic soluble salts and is considered to be most comprehensive indicator of a soil’s corrosivity. Typically, the lower the resistivity, the higher will be the corrosivity as indicated in the following Table. Corrosivity ratings based on soil resistivity

25

Grounding Soil Resistivity

26

13

Grounding Indicative data – Soil Resistivity – Moisture and Temperature effect Moisture Content % by w eight

Soil Resistivity (Approximate), ohm-cm Top Soil >10000000000 250,000 265,000 53,000 19,000 12,000 6400

0 2.5 5 10 15 20 30

Sandy Loam >10000000000 150,000 43,000 18,500 10,500 6300 4200

Tem perature in Degree C

Soil Resistivity (Approximate), ohm-cm

20

7200

10

9900

0

13,800 – 30,000

-5

79,000

-15

330,000

27

Grounding Indicative data – Soil Resistivity – Soil containing Salt Effect of Salt content % by w eight of Moisture

Soil Resistivity (Approximate), ohm-cm

0

10,700

0.1

1800

1.0

460

5

190

10

130

20

100

Effect of tem perature in Degree C on resistivity of soil containing salt (Sandy loam, 20% m oisture, salt 5% of w eight of m oisture) 20

Soil Resistivity (Approximate), ohm-cm 110

10

142

1

190

-5

312

-13

1440 28

14

Grounding IS 3043 – Code of Practice for Earthing Earthing Resistance, RE •

Resistance of Metal Electrode, RM

•

Contact resistance between electrode and soil, RD

•

Resistance of earthing conductor that runs between the main earthing bus bar and the earthing electrode, R C

•

RE = RM + RD + RC

29

Grounding IS 3043 – Code of Practice for Earthing Earthing Resistance, RE

30

15

Grounding IS 3043 – Code of Practice for Earthing Earthing Chamber (Pit) Example

31

Grounding IS 3043 – Code of Practice for Earthing Material selection for Earthing electrodes •

Should exhibit galvanic potential

•

Resistant to corrosion, Copper, Galvanized Mild Steel

•

Damage to cables and other underground service s due to electrolytic actions between dissimilar metals

•

Material compatible with other metals in vicinity

32

16

Wire Sizes Wire Size (cross sectional area) depends upon following: •

Admissible Maximum temperature

•

Admissible Voltage drop

•

Electromechanical stresses likely to occur due to short circuits

•

Other mechanical stresses to which the conductors may be exposed

•

Series/ Parallel connections of PV modules 33

Wire Sizes Grounding wire size •

For PV Module – Shall not be less than the supply wires used in PV Module, but not less than 4 sq. mm

•

For Installation – Not less than 10 sq mm

34

17

Fuse / Circuit Breaker rating As per IEC 61730-1, the Current rating of Series Fuse / Circuit Breaker is required to be at least 1.25 times of Short Circuit Current rating

35

THANK YOU.

18

Lightning Protection Systems

© 2011 Underwriters Laboratories Inc.

Standard References 

IS:2309:1989 – Protection of buildings and allied structures against lightning



IEC 61643-1 – replaced by: IEC 61643-11



IEC 1024-1 – replaced by: EN 62305-3



IEC 62305-3 – Protection against lightning(Physical damage to structures and life hazard)



IEC 62305-1 – Protection against lightning : General principle

2

1

Understanding the Lightning Discharge Upw ard leader propagates tow ard down leader to com plete ionised path between clouds & ground

Cloud electrification – E Field established between clouds & ground

E Fields >200kV/m

E Fields 5-15kV/m

Dow n leader approaches, E Field increases to point of initiation of upward streamers 3

Lightning Atmospheric di scharge of electricity may be accompanied by thunder or dust storms.

Can travel at speeds of 2,20,000 km/h (1,40,000 mph)

Can reach temperatures approaching 30, 000°C (54,000°F), hot enough to fuse silica sand into glass channels

4

2

Lightning Protection Systems System s de signed to protect a structure from damage due to lightning strike s by intercepting such strike s and safely passing their extremely high voltage currents to "ground". Most lightning protection systems include a network of lightning rods, metal conductors, and ground electrodes designed to provide a low resistance path to ground for potential strikes.

5

Lightning Protection System - Components ► Lightning Rod or Air Terminal ► Down conductor ► Surge Protection Device

► Other components

6

3

Lightning rod or Air terminations

7

Down Conductor

8

4

Surge Protection Device

Appliance designed to protect electrical devices from voltage spikes. Surge arresters can be viewed as a simple switch between two lines. When voltage rises as a result of a transient, the switch operates by diverting the energy away from the equipment.

9

Other Components

10

5

Positioning the Air-Termination System-Protection Angle Method

where, A - tip of an air-termination rod B - reference plane

OC - radius of protected area h1 - height of an air-termination rod above the reference plane of the area to be protected α - protection angle

11

Example:

w here, 1 - air-termination m ast 2 - protected structure (Solar PV module array in our case) 3 - ground being the reference plane 4 - intersection between protection cones s - separation distance α - protection angle complying 12

6

Example:

Note: During verification of Solar power plants lightning arrester inspection will depend upon the type of arresters used at site.

13

Rolling sphere radius, mesh size and protection angle:

14

7

Position Angle Method (PAM)

15

Number of Thunderstorm Days Map of India

16

8

LA Photos

17

18

9

19

20

10

21

22

11

23

Lightning Protection Devices - Video

24

12

THANK YOU.

13

Solar Photovoltaic Power Plant - Power Evacuation System

© 2011 Underwriters Laboratories Inc.

Photovoltaic System

1

Power Evacuation System Design • • • •

LT panel & associated switchgear Power Transformer specification HT panel & associated switchgear HT Metering

Power Evacuation Scheme

A typical MW Power Evacuation scheme

4

2

Power Evacuation Schematic

5

Design – Power Evacuation

The power evacuation scheme broadly consists of • LT panels & associated switchgear • Power transformer of suitable rating • HT Panel & Switchgear

• HT Metering • DP structure to facilitate power evacuation to the HT line

6

3

L T Panel • Used to provide for interconnection of several inverter AC outputs with required protection and metering • It contains necessary breakers for isolating • Metering provisions may be added if desired • Output of LT panel connected to LT winding of Power transformer

• LT panel is generally indoor rated (IP 30) • Some measurements from LT panel can be integrated to power plant SCADA 7

LT Panel – Switchgear Selection •

•

Breaker current rating should be at least 25 % higher than the max current at the Inverter out put. The breaking capacity > max fault current Suitable CTs to provided in each phase for overcurrent protection

•

The power supply for tripping mechanism should be same as the battery voltage in auxiliary DC power supply. Typically 110V/ 48V are used

•

Gland plates should be provisioned to receive the cables

•

Suitable termination should be made if the connection between LT Panel & Transformer is by bus duct The bus bar sizes should be adequately rated to withstand max fault levels

•

8

4

Power Transformer (1/2) • Power transformer rating to be suitably designed based on the solar farm output rating • Primary Voltage same as the Output voltage of the PCU - LT winding

can be 433 volts (standard) or any other voltage to match with the inverter output • Secondary Voltage be equal to the Grid voltage to which power to be evacuated - HT winding to chosen based on the inter connection voltage – 11kV / 33 kV / 66 kV?? • KVA rating based on the number & rating of Inverters connected to the Primary • Should be suitable for operation with pulsed Inverter • Impedance of max 6 % • Minimum iron loss • Off load taps +/- 2.5 % and +/-5 % on HV side 9

Power Transformer (2/2) • Preferred vector grouping is DYN11 (standard) • Transformer to have multiple LT windings if used with transformer less inverters • To comply with the requirements of IS : 2026 • Provide all protections like Buchholtz relay, Oil Temp ,Winding Temp, Silica gel breather etc. • Should specify whether you need Cable Box type termination or bus duct termination • To be provided with a Shield winding and grounded to the tank • Either of the transformer windings neutral will need to be earthed to provide a quick path for clearing of earth faults • Neutral grounded resistors or neutral grounded transformers to be used to facilitate the neutral point earthing

10

5

HT Panel & Switchgear (1/2) • HT panel provides for interconnection from the HT winding of the transformer to the HT transmission line • HT panel also provides for protection, interlocking , annunciation

and tripping • HT panel typically consists of suitably rated HT breakers, VT’s , CT’s , relays, meters, relevant annunciation panel etc. • The breaker should be of appropriate voltage class depending on the grid voltage • The current rating should be at least 25% higher than the current that is expected to be pumped • Rating of the HT panel should be chosen keeping in view of the max fault current that it should withstand depending on the substation

11

HT Panel & Switchgear (2/2) • Protective relays like O/C, E/F , IDMT, Reverse Power relay etc. to be provided • HT Panel can house the Energy meter to record the power exported • In some cases separate metering kiosk including a Check meter (utility) will have to be placed near the 2 Pole / 4 Pole Structure • The cable from HT Panel or Metering kiosk needs to be terminated on a 2 Pole structure or 4 Pole structure. • GOD switch with fuse will be mounted on the structure. Rating should match with the system requirements. • The transmission line will be terminated on this. • Suitable Lightning Arrestor should be provided • Where double circuit termination is required , 4 pole structure may be used

12

6

HT Metering

• HT metering panel provides for metering of the energy fed to the grid on the HT side

• This meter is generally used by the utility authorities to quantify the amount of energy fed into the grid. • HT meter to conform to relevant standards.

• HT meter to have facility for communication with standard SCADA systems

13

Transmission Line (1/2) • The power generated at the Solar Plant has to be delivered at the Substation (grid injection point ). This calls for an Overhead transmission line between SPP and S/S • The components in the overhead transmission line – - Pole with concrete foundation - Insulators - Conductors - Cross arms - Stays - Earthing - Ground Operated Device - Danger Boards

- Anti climbing device

• Each of the above items have to comply with relevant IS standards

14

7

Transmission Line (2/2) • Poles : PCC / Steel Joists / Steel Tubular / Lattice Towers • Cross Arms : Made of Steel Channels size depending on type of pole & location

• Insulators : Pin type / Disc Type as necessary • Conductors : ACSR (Aluminium Conductor Steel Reinforced) / AAAC (All Alloy Aluminium Conductor) / ABC (Aerial Bunched Cables) • Objective to have minimum losses • Conductor based on the current and the length of the transmission line • Foundation design for Poles based on soil bearing capacity / terrain 15

Evacuation at Grid (1/2) • At the receiving station it is necessary to control, protect and monitor the power supplied • A bay shall generally comprise of – Circuit Breaker – Isolator – Lightning Arrestor – CT – PT

16

8

Evacuation at Grid (2/2) • The control Panel located inside the Control Room • Voltmeters, Ammeters • Protective Relays • Alarm annunciators • Auto cut off facility

• Monitoring relays • Availability Based Tariff metering system to record the supplied energy 17

THANK YOU.

9

Design Criteria of PV system

© 2011 Underwriters Laboratories Inc.

Design Creteria of Standalone PV system • Sizing of load • Battery bank sizing • PV array sizing

2

1

Sizing of load • • •

Identify the loads (fan, lights etc). Hour of operation. Number of days per week

3

Load Calculations Load Type

Numbers

Hour of operation

Power (W)

kWh

fan

16

7

60

6.72

Tube lights

15

7

40

4.2

computer s

3

5

200

3

printer

2

1

300

0.60

Xerox machine

1

1

2000

2

AC

2

4.5

2000

18.00

AC Energy required to run these loads on 230V AC

34.52 kWh

4

2

Decide on system voltage Capacity of power plant

System Voltage

Less than 1 kW

12 V

1 – 3 kW

24 V

3 – 8 kW

48 – 96 V

10 – 20 kW

120 – 240 V

5

Battery Bank Sizing

6

3

PV array Sizing

7

Example What will be the system required to run 4 CFL (11W) for 4 hours with 3 days of autonomy? • Load calculation = 4 (CFL) X 11 (W) X 4 (Hours) = 176 Wh • System Voltage = 12 V (less than 1 kW). Battery bank Sizing • Ah per day required = 176 / 12 = 14.6 Ah • Battery capacity = 3 (Autonomy) X 14.6 Ah (Ah per day) / 0.9 (batt. eff.) X 0.8 (DOD) =

• • • • •

60.83 Ah = 12 V, 75 Ah (As 60 Ah battery not available) PV array sizing Ah Required from PV array = 14.6 Ah (Ah required for load) / 0.8 (inverter eff.) = 18.25 Ah Average current drawn = 18.25 (Ah from PV )/ 5 (ESSH) = 3.65 A This ampere can be achieved by looking the panel specification, generally 75 Wp panel delivers 3.5 to 4 A current and 12 V. Panel in series = 3.65 (Avg. current drawn) / current of one panel = 1 Number Panel in parallel = 12 (system voltage) / 12 (Module voltage) = 1 Number 8

4

Question Q1 . What will be the system required to run 2

CFL (11W) & 1 DC fan (20 W) for 3 hours with 3 days of autonomy? Q2 What will be the system required to run 2 CFL (11W) for 3 hours with 3 days of autonomy?

9

THANK YOU.

5

PV System – Operation and Maintenance.

© 2011 Underwriters Laboratories Inc.

Check list of Maintenance. 1. 2. 3. 4. 5. 6. 7. 8. 9.

Module. Washing the PV array. Junction Box inspection. Disconnect device inspection. Inspection of cables. Checking the operation of the inverter . Checking the output of string voltages and currents. Spare Parts stock management Documenting any deficiencies.

2

1

Types of maintenance.

 Predictive.  Preventive.  Corrective.

3

Predictive maintenance  It tries to predict the plant performance in the future, to prevent possible malfunctions by certain actions.  i.e. If an element life time is supposed to be X years, it can be programmed to be substituted the year X-1, in order to avoid a serious failure.

4

2

Preventive maintenance  It tries to set periodical tasks to guarantee the plant lifetime.  i.e. The Suntracker oil should be regularly replaced for efficient operation.

5

Corrective maintenance.

 It tries to repair incidences which have already happened and try to avoid their repetition.

 i.e. Atmospheric phenomenon (such us wind, storms, etc.) can damage any element in the plant. Also, manufacturing defects.

6

3

System producing less than expected, it could be due to: o o o o o o o o

Shade from trees, other buildings, overhead cables, aerials. Mismatch of ratings between PV panel and inverter. Regulation problems/defective inverter. Mismatch of panels connected in array. Faults in the DC wiring. Defective modules. Defective (module) bypass diodes. Imbalance (voltage, current, frequency) caused by the utility grid.

7

Panel Analysis.

To detect the defective panels within the array:

a. Test both the voltage and the current for each panel:  The voltage may b e reduced if a cell has any defects.

Production defects b. The hot spots may produce a voltage reduction:  They can be detected visually, but a thermo graphic camera can help to find them out.

8

4

Module Maintenance.

They should be visually detected.

 Defective cells.  Yellowing (The panel becomes yellow)  Defective connection boxes.  Broken glass.  Delamination  Others..

9

Mounting structure inseption.

 Check for corrosion in the mounting structures.  Document if any corroded parts.

 Repaint the corroded parts in order to prevent further destruction of the structure.

10

5

Module wiring and ground inseption.

 Check the wiring for signs of chewing by squirrels, and look for cuts, gashes, or worn spots in the wiring’s insulation. Replace any damaged wire runs.  Check the frame ground connections between modules.

11

Check for any hanging wires under the modules.

Tie all the wires together with a cable ties.

12

6

Tighten all loose nuts and bolts, holding the modules to the mounting rack and to the mounting clips.

13

Washing the PV array.

 Solar Panels are always exposed to the external environment which leads to deposition of dust and debris. This causes shading in part of the array hence considerably reducing the output of PV array.

 Regular cleaning of PV array to remove the deposits on the panels is necessary for its efficient performance.  Use a clean sponge or cloth for cleaning, to avoid scratching on the module and no chemical should be left on the glass after cleaning. 14

7

Self-Cleaning Solar Panels.

 Washing the panels can be time-consuming or require costly automation and it takes a lot of water, a precious resource.  With the new technology, solar panels can be automatically cleaned without water or labor.  The panels are made-up of electrodynamic screens (EDS).

15

Junction Box.  Open the junction box and look for any dirty, loose, creatures or broken connections, and correct as necessary.  The junction boxes should be IP 65/66/67 rated.

17

8

Disconnect device. Preventive:

• Periodical inspections will be done, specially in the connections. • If any defect is detected, the device will be immediately replaced. • The spare part stock is important. • Maintain a log of number of time it tripped.

18

Cable Preventive

 To check the connections between the different equipments.  To check those parts where the cable cover can be damaged.  Check high losses/voltage drop in cables. Check the calculations, possibly replace with larger cables. 19

9

Preventive maintenance.

It is necessary to define the maintenance tasks and their periodicity and then create a record of preventive maintenance on every element, with the date of accomplishment.

Example: Preventive maintenance calendar 20XX Task

Periodicity

Checking the cable state

Yearly

Retightening of the electrical connections

Yearly

Date

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String Inverters compared to Central Inverters.

     

Reliability and Longer Life. Productivity. Ease of Installation. Flexibility. Space and Heat of Inverters. Higher Power Inverters have to be used.

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Disadvantages of String inverters compared to Central Inverters.

© 2011 Underwriters Laboratories Inc.

Cost.  String inverters typically costs twice that of Central Inverter.  This is the biggest disadvantage of string inverter compared to Central inverters.

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Placement of String inverters

 String inverters are place on the rack below the modules.  This is said to cause problems as it is placed on the hottest part of the solar system and could lead to problems in case of high insolation areas.

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Not useful in utility solar power plants.  Solar Power Plants of more than 1 MW in size have not used string inverters.  As string inverters are more useful in power plants of smaller size where maximum power is needed and where there are problems of shading, debris etc.

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Inverter Output Performances.

1. Output Voltage. 2. Output Current. 3. Output Power. 4. Output Power Factor. 5. Efficiency. 6. DC injection Current. 7. Total Harmonic Distortion (THD). 8. Current Harmonic Test.

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Inverter overheating due to clogged vents, bad ventilation.

 Clean inverter.  Relocate inverter.  Improve room ventilation.

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No DC voltage at the inverter input. Fault/possible cause/solution.

• •

• • •

Too dark, not enough light. Come back at a better time when there is enough sunlight. Main DC disconnect/isolator in open position? Defective disconnect/isolator ? Check voltage at disconnect/isolator input. String fuses blown(lightning strike). Excess voltage suppressor has short-circuited the array to earth. Check excess voltage suppressor.

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Inverter indicates DC input voltage during the day but nothing is being put onto the grid.  Blown fuses, activated circuit breakers and ground fault interrupts on the AC side between inverter and grid, The main utility fuse, Check these.

 The inverter has detected a fault in the array and shut down. Check any fault indicators. Test strings individually in the PV array combiner box.  Possibly isolate the string which is causing the inverter to shut down by disconnecting one string at a time until string with fault is identified.  The inverter has detected a grid fault or grid operating outside design parameters for the inverter causing the inverter to shut down.

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Incorrect installation.

o o o o o

String not correctly wired. Not plugged into connectors properly. Loose connections. No voltage on terminals in PV array combiner box. Incorrect DC polarity in circuit.

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Fault indication : The array current is lower than would be expected under high conditions of solar radiation. Fault/possible cause/solution  Check if the array is shaded or if there is dirt on it. Remove source of shade or clean.  Defects in module, Strings cables caused by storms or lightning etc. ? Visual inspection, Check strings in PV array combiner box - Voc , Isc, Impp. Take measurements in conditions of constant sun, not in changeable conditions. Ideally also test with peak watt meter and compare with measurements made during commissioning.  Disconnected terminal? Loose connectors? Cont… 31

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possible cause/solution.

 Defective bypass diodes in individual modules-caused by lightning / voltage surge? Short circuited diodes bridging over cell strings and reducing module output. Use process of elimination-first strings, then modules.  Damage to module or cells caused by lightning. Cell damage may not be visible. Take module output reading. Replace module.  Short circuit in module junction box due to moisture and compare with data sheet.

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Stand-alone system maintence.

© 2011 Underwriters Laboratories Inc.

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Battery Types.

 The most commonly used batteries in PV systems are of the lead-acid type.  They are rechargeable, easily maintained, inexpensive and available in different sizes and options. 34

Battery maintenance. •

Connections are sound and not corroded-petroleum jelly is good protection.

•

Electrolyte level is sufficient-top up with deionized/distilled water if required.

•

Clean top of batteries to remove dirt, dust & moisture.

•

The battery room should be clean, dry & cool, with proper lighting & ventilation.

•

Check specific gravity of electrolyte with hydrometer in the event of flooded cell. 35

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Adjustment of Sp. Gravity Procedure: 

After batteries are fully charged, the sp. Gravity of the electrolyte of all cells to be adjusted to the service gravity i.e. 1.210 /1.250 ± 0.005, at 27ºc. the batteries to be put on charge for proper mixing.



If sp. Gravity in cells more than service gravity corrected to 27 ºC. Take out acid and add battery grade water, when on charge for proper mixing adjust sp. Gravity to the service gravity corrected to 27 ºC. As applicable with respective batteries.



If the sp. Gravity of the cells less than the service gravity at 27 ºC take out acid and add 1.400 sp. Gr. Acid by few drops, on charge for proper mixing. Adjust the sp. Gravity to the service gravity at 27 ºC as applicable.



After adjustment of the specific gravity, continue the charging for 1- 2 hours for proper mixing of the electrolyte. Stop the charging and allow the batteries to cool, before commissioning. 36

Performance.

The performance of storage batteries is described two ways. They are  The amp-hour capacity and  The depth of cycling.

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The amp-hour capacity.

 The number of amp-hours a battery can deliver, is simply the number of amps of current it can discharge, multiplied by the number of hours it can deliver that current.  Theoretically, a 200 amp-hour battery should be able to deliver either 200 amps for one hour, 50 amps for 4 hours, 4 amps for 50 hours, or one amp for 200 hours. 38

Battery is not charging.

 Battery is not charging Measure PV array open circuit voltage and confirm it is within normal limits. If voltage is low or zero, check the connections at the PV array itself. Disconnect the PV from the controller when working on the PV system.

 Measure PV voltage and battery voltage at charge controller terminals if voltage at the terminals is the same the PV array is charging the battery. If PV voltage is close to open circuit voltage of the panels and the battery voltage is low, the controller is not charging the batteries and may be damaged.

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Charge Controller maintenance.

When performing maintenance, disconnect any battery first; remove connections on a battery, then from the solar controller.

 Always make sure there is no corrosion around battery terminals.  Make sure solar panels and loads do not exceed the solar controller’s ratings.  Tighten all terminals screws. Inspect for loose, broken or burnt wire connections. Be certain no loose wire strands are touching other terminals.  Ensure the solar controller is securely mounted or placed upright in a clean environment. Inspect for dirt, debris, insects and corrosion. Make sure the solar controller’s work mode is set to the desired mode.

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Spare Parts stock management.

 A bad management of supplies can mean complete days of stop of an installation.  It is essential to have an updated list of all the spare parts in the plant and to assure there is enough quantity.

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Essential spare parts. • • • • • • •

Solar module. Solar array cable. Junction Boxes. Fuses. Switches. batteries. battery charge controls.

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Instructions For each installation provide a separate a)user manual, b)technician’s manual and c)installation manual, in the language most appropriate to the installation site. The manuals must include the following information: User manual: • Daily, weekly and monthly maintenance tasks • Health and safety guidance.

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Technicians’ manual:

• • • • •

Periodic preventative maintenance checks. Diagnostic and repair procedures. Health and safety guidance. Itemized list of spare parts including part numbers. Resource recovery and recycling procedures.

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Installation manual

 Installation design rationale.  Site-specific drawings (if applicable).  Full installation instructions, including array siting recommendations.  Wiring diagrams.  Full commissioning instructions.  Health and safety guidance.

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Supervisory Control and Data Acquisition (SCADA) System:



The SCADA system shall incorporate integrated system control and data acquisition facilities.



It should be capable of communicating with individual Inverters and provide information of the entire Solar PV Grid connected power plant.



The SCADA shall provide information of the instantaneous output energy and cumulative energy for each of the Inverters as well as for the entire power plant, changing of operator modes. 46

Supervisory Control and Data Acquisition (SCADA) System:  The integrated SCADA shall have the feature to be used both locally (at two locations) via a local computer and also remotely via VSAT or the Web using either a standard modem or a GSM / WIFI modem.

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Examples of bad design / manufacture / workmanship

© 2011 Underwriters Laboratories Inc.

Examples of failures scorched points

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Examples of failures 72,2°C

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SP01

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7,5°C

Contact problems (thermographic pictures of modules)

Examples of failures Thermographic pictures of modules with different failures

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Examples of failures Pictures of different failures

Examples of failures Pictures of different failures

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Examples of failures Pictures of different failures

Examples of failures Pictures of different failures

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Examples of Deficiencies

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Examples of Deficiencies

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Examples of Deficiencies

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Examples of Deficiencies

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Examples of Deficiencies

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Examples of deficiencies in installation

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Examples of deficiencies in installation

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Thermal Images

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Cognizance for site selection

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Training Need in following areas

• PV System Installer certification programme intended to meet industry requirement through cooperation with leading PV stake holders, NGO’s and professional associations

• Work shop for system integrators / artisans @ District level • Fundamentals of Solar Energy • Familiarization of - PV Module and its characteristic - B O S components

• Criticality of integration parameters • Do’s & Do - not’s of system integration

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THANK YOU.

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