bipv training presentation 7-10-08

8/14/2019 BIPV Training Presentation 7-10-08

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Photovoltaic

Design Overview

(949) 939-8881

[email protected]

Chris SmithSenior Design Engineer

Solar Technologies


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2PV Overview v1.0 7/2008

Solar Cell

The basic photovoltaic device that generates dc

electricity when exposed to light

A typical silicon solar cell produces about 0.6 volt and

around 6 amps and 3.5 Watts for larger area cells.


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Types of Solar Cells Monocrystalline silicon cell

High quality starting material (chip manufacture)

High efficiency (~ 14% to 17%), but expensive

Polycrystalline silicon cell

Most common type (largest market share)

Efficiency ~13% to 15%

Amorphous (aka Thin Film) cell Thin layers vacuum deposited onto glass Efficiency ~ 5% to 8%

New technology
http://www.physorg.com/newman/gfx/news/070124.gifhttp://www.cnjmsy.com/en/PIC/PIC/200782817170.jpg


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Connecting Solar Cells Together Solar Module

Solar cells connected together

electrically in series

Front of one is connected to the backof its neighbor

One +ve lead and one ve lead


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Photovoltaic Modules Solar Module A complete, environmentally protected unit containing

solar cells and other components, designed to generate dc

power when exposed to sunlight.

Does not store any electricity

Polycrystallinemodule Monocrystallinemodule


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Electrical Characteristics of Modules Power output is directly proportional to irradiance

Irradiance (in Watts per sq meter) measures the brightness

(energy) of the light

Power output is reduced as the temperature increases

Four main electrical parameters

Open circuit voltage (Voc)

Short circuit current (Isc)

Maximum Power Point (Vmpp, Impp)


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Review of Electrical ConceptsCurrent - measured in Amps I

Voltage - measured in Volts V (or U)

Power - measure in Watts W or kW

Energy - measured in Kilowatt-hours kWh

Power = Voltage x Current

Energy = Power x Time


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Connecting Modules Together

Solar module

24.2 V / 7.45 A

180 W

Solar Array

48.4 V / 7.45 A

360 W

Solar module

24.2 V / 7.45 A

180 W

Strings (series connection)

Module voltages are additive

Current remains the same

Max voltage = 600V


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Connecting Modules Together (cont)

Solar Array

48.4 V / 14.90 A720 W

Solar module

24.2 V / 7.45 A

180 W

Solar module

24.2 V / 7.45 A

180 W

Solar module

24.2 V / 7.45 A

165 W

Solar module

24.2 V / 7.45 A

180 W

Serial / parallel connection

Voltages in series are

additive

Total current (from theindividual strings) is

additive


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String Rules Modules connected together into strings must all have

the same orientation and tilt

Strings connected in parallel must match That is, have the same number of the same type of modules


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Grid-Tied Inverters Generate utility-quality AC power from DC input

Synchs up with grid frequency

High quality sine wave

208v, 240v, 277v capable Single and three phase capable

Inverter efficiency

Typically ~95%

Max Power Point (MPP) tracking

Inverters continuously adjust the

voltage in order to get the most

power out of the modules


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Grid-Tied Inverters (cont.) Inverters do not like high temperatures

Shuts down whenever grid goes down

Records how much power hasbeen generated


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Orientation and Tilt Factor (Los Angeles)

Flat

0

4:12

18

7:12

30

12:12

45

21:12

60

Vertical

90

South 89% 97% 100% 97% 89% 58%

SSE, SSW 89% 97% 99% 96% 88% 59%

SE, SW 89% 95% 96% 93% 85% 60%

ESE, WSW 89% 92% 91% 87% 79% 57%

E, W 89% 88% 84% 78% 70% 52%


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Module Shading Effects

Each of these results in a 50% loss of power


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Module Shading Effects

This results in a 100% loss of power


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A Grid-Tied PV System

PhotovoltaicArray

Sunny BoyInverter

Breakers

Meter

1500 kw/h1450 kw/h1400 kw/h1300 kw/h1200 kw/h1100 kw/h1000 kw/h900 kw/h800 kw/h700 kw/h600 kw/h500 kw/h400 kw/h350 kw/h300 kw/h250 kw/h200 kw/h150 kw/h100 kw/h50 kw/h0 kw/h


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bipv training presentation 7-10-08

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