Layout of a silicon solar cell

Components of a PV system

Module – consists of many cells wired together

Support structureInverter – converts DC module output to

AC power at the right voltage and frequency for transfer to the grid

Concentrating mirrors or lens for concentrating PV systems

Types of PV cells

Single-crystallineMulti-crystallineThin-film amorphous siliconThin-film compound semiconductorsThin-film multi-crystallineNano-crystalline dye-sensitized cellsPlastic cells

Thin-film compound semiconductors

Cadmium telluride (CdTe)Copper-indium-diselenide (CuInSe2, CIS)Copper-indium-gallium-diselenide (CIGS)Gallium arsenide (GaAs)

Best efficiencies achieved as of 2009

U n co n ce n tr a ted S u n lig h t C o n ce n tr a te d S u n lig h t Te ch n o lo g y C e ll M o d u le C e ll C o n ce n tr a tio n F a cto r

S in g le- ju n ctio n s ilic o n se m ic o n d u cto r c- S i 2 5 .0 2 2 .9 2 7 .6 9 2 m -S i 2 0 .4 1 5 .5 a - S i 9 .5 t h in- film S i 1 6 .7 8 .2

S in g le -ju n ctio n co m p o u n d sem ico n d u cto rs C d Te 1 6 .7 1 0 .9 C IG S 1 9 .4 1 3 .5 2 1 .8 1 4 In P 2 2 .1 th in - film G a A s 2 6 .1 2 8 .8 2 3 2 m -G a A s 1 8 .4

M u lti- ju n ctio n se m ic o n d u cto rs a - S i/µ c - S i 11 .7 a - S i/a- S iG e/a -S iG e 1 0 .4 th in - film G a A s/C IS 2 5 .8 G a In P /G a A s 3 0 .3 G a In P /G a A s/G e 3 2 .0 4 0 .7 2 4 0 G a In P /G a In A s/G e 4 1 .1 4 5 4

P h o to c h e m ic a l a n d O rg a n ic D y e-sen s itized 1 0 .4 O rg a n ic 5 .2

Trend in efficiency of PV cells and modules

Structure of the GaInP/GaInAs/Gemulti-junction Cell

Factors affecting module efficiency

Solar irradiance – efficiency peaks at around 500 W/m2 for non-concentrating cells

Temperature – efficiency decreases with increasing temperature, more so for c-Si and CIGS, less for a-Si and CdTe

Dust – can reduce output by 3-6% in desert areas

Module efficiency vs solar irradiance, theoretical calculations

Module efficiency vs solar irradiance, measurements

System efficiency is the product of

Module efficiencyInverter efficiencyMPP-tracking efficiency

Inverter & MPP Efficiency, measured

MPP-tracking efficiency

0

10

20

30

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70

80

90

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0 20 40 60 80 100

Load (%)

MP

P T

rack

ing

Eff

icie

ncy

(%

)

Afternoon

Morning

BiPV on single-family house in Finland

BiPV on a single-family house in Maine

PV modules (attached to insulation) on a horizontal flat roof

Source: www.powerlight.com

PV modules servings as shading louvres onthe Netherlands Energy Research Foundation building

Supplemental figure PV modules as vertical shading louvres on the SBIC East head office building in Tokyo

PV modules providing partial shading in the atrium of the Brundtland Centre (Denmark, left) and Kowa Elementary School (Tokyo, right)

Source: Shinkenchiku-Sha Source: Henrik Sorensen, Esbensen Consulting

The Netherlands

Growth in annual PV production

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6000

1998 2000 2002 2004 2006 2008

Year

An

nu

al In

stal

lati

on

of

PV

(M

Wp-A

C)

Rest of WorldUSARest of EuropeSpainGermanyJapan

Growth in installed PV power

0

4000

8000

12000

16000

1998 2000 2002 2004 2006 2008

Year

Cap

aci

ty (

MW

p-A

C)

Rest of WorldUSARest of EuropeSpainGermanyJapan

Price of Photovoltaic Module

1

10

100

0.1 1 10 100 1000 10000

Cumulative global PV module shipments in MWp

Pri

ce

of

PV

mo

du

les

(U

S$

/Wp)

Triple-junction a-Si on laminated roofing

PV Scenario

0

10

20

30

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50

60

70

0

50

100

150

200

2000 2005 2010 2015 2020

Co

st

of

Ele

ctr

icit

y (c

en

ts/k

Wh

)

Pe

ak

Po

we

r (G

W)

20%/yr growth in production capacityafter 2006, PR=0.8

Cost

Installed Peak Power

PV Scenario

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50

60

70

0

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150

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2000 2005 2010 2015 2020

Co

st

of

Ele

ctr

icit

y (c

en

ts/k

Wh

)

Pe

ak

Po

we

r (G

W)

30%/yr growth in production capacityafter 2006, PR=0.8

Cost

Installed Peak Power

Solar Module Annual Tilt

Modules are tilted at latitude angle to be aimed at sun on equinoxes; at solstices, they are off by the obliquity angle

070206

NP

SPNP

SP

NP

SP

NP

SP

+23.5° tilt

-23.5°

SummerSolstice

WinterSolstice

Fall

Spring

Horizontal Plane

Zenith Angle of Sun

070206

Zeni

Zenith (up)

NorthPole

Equator

To Sun

Equatorial PlaneLatitude Angle

Solar Declination Angle

ZenithAngle

To SunYou are

here!

Sun’s zenith angle is measured from local vertical

South Pole

PV ARRAY: SOLAR NOON TILT DATA

Latitude = 28 Degrees North

Optimum Solar Module Tilt

Website calculations

050208

Month SunAltitude

ArrayTilt

ArrayPoints to:

JAN 42 48 South

FEB 51 39 South

MAR 62 28 South

APR 74 16 South

MAY 82 8 South

JUN 85 5 South

JUL 82 8 South

AUG 74 16 South

SEP 62 28 South

OCT 50 40 South

NOV 42 48 South

DEC 39 51 South

Array Tilt = 90 degrees - Sun Altitude