Crystalline Si Photovoltaics

Arthur Weeber

2

Outline

• Short introduction ECN• Introduction ECN Solar Energy• General Si solar cells• Crystalline Si Photovoltaics

- Feedstock- Wafering- Cell processing- Module technology- Costs and environmental

• Summary

3

Petten: ECN; NRG; JRC; TYCO

4

Targets ECN research

Transition to renewable energy supply:

efficiency improvement

development of renewable energy

clean use of fossil fuels

maximum reliabilityminimum environmental burden

optimal cost effectiveness

5

ECN Programme units

Strategically Policy Studies

Energy savings Energy Efficiency in IndustryRenewable Energy in the Built Environment

Renewable energy Solar EnergyWind EnergyBiomass, Coal & Environmental research

Clean use fossil fuels Hydrogen & Clean fossil fuels

Support Engineering & Services

6

Fuel Cell Technology

19%

Clean Use of Fossil Fuels

16%

RE in the Built Environment

8%

Wind Energy12%

Solar Energy15%

Energy Eff. in the Industry

7%

Policy Studies 11%

Biomass13%

Turnover share per unit (2005)

ECN Solar Energy

8

Solar Energy

• Silicon Photovoltaics• Thin-Film Photovoltaics• PV Module Technology

Objective:• Price of solar electricity in 2015 the same as consumer

electricity price, and after that even lower- High efficiency- Reduction of material use- Cost effective and environmental friendly processes and

products- Long lifetime of the modules

9

PV technology development:no revolution, but evolution

0 5 10 15 20 25module efficiency (%)

mod

ule

pric

e (€

/Wp)

1

2

3

4

0

c-Sitf-Si

& CIGSS

new concepts

2004

2010

2020

>2030

OSC

technology families technology generations

(free afterW. Hoffmann)

tf-Si = thin-film silicon

CIGSS = copper-indium/gallium-selenium/sulfur

c-Si = wafer-typecrystalline silicon

OSC = organic solar cells

new concepts = advanced versions ofexisting technologies & new conversion principles

10

ECN Solar EnergyThin-film photovoltaics

• Sensitised oxides – efficiency, stability, manufacturing technology– solid state version: in 2015 η=8% for 10x10 cm2

device with >10 year outdoor stability

11

ECN Solar Energy

Thin-film photovoltaics• Organic solar cells

– device fabrication, efficiency and stability– in 2015 η=8% for 10x10 cm2 device

with >10 year outdoor stability

0.5

1.0

1.5

2.0

Effic

ienc

y (%

)

Year

400 600 8000

25

50

wavelength (nm)

EQ

E (%

)

2002 2003 2004 2005

Collaboration of ECN, TNO

S

S OR

MeOn R2R2 NC

CN1

OC10H21

H3CO

+

12

ECN Solar Energy

Thin-film photovoltaics• Thin-film silicon

– R-2-R deposition of (n,i,p) silicon on foils– Development of thin-film Si tandems– In 2015 a 0.3x1 m2 PV module η=12% at 0.8€/Wp

13

New concepts•improved spectrum utilization•flat plate concentrator

ECN Solar Energy1

a2

1

Fr

Ri

Re

AM1.5

2

1

a2

1

Fr

Ri

Re

AM1.5

2

wavelength [nm]

1.6

1.2

0.8

0.4

400 800 1200 1600 2000 24000.0

available for conversion in crystalline Si

infraredvisibleUVsolar spectrum (Air Mass 1.5; 1000 W/m2)

pow

er [W

/(m2 .n

m)]

1100 nm ∼1.1 eV = Si bandgap

14

ECN Solar Energy

PV systems • grid interaction• system design & monitoring• standards and guidelines

15

Crystalline Si PV technology

Objective:• Price of solar electricity in 2015 the same as consumer

electricity price, and after that even lower- High efficiency- 18% module efficiency for crystalline Si PV

- Reduction of material usage- Thin wafers (<150 µm compared to current >240 µm)

- Cost effective and environmental friendly processes and products

- Long lifetime of the modules (>30 yr for crystalline Si)

- Energy Pay Back Time < 1 yr

16

Cell structure Crystalline silicon solar cell (minority carrier device)

• Base: B doped Si (p-type)• Emitter: P doped layer (n-type)

- Recombination losses in base and emitter- Voltage over pn junction

• Metallization for contacts- Shading losses- Resistance losses

• Antireflection coating to enhance current

• Surfaces: recombination losses

+-+

-

-

+

base

emitter

ARC

ohmic contact external load

back ohmic contact/ BSF

collection

recombination

17

Cell structure Crystalline silicon solar cell

• Base: B doped Si (p-type)• Emitter: P doped layer (n-type)- Voltage over pn junction- Recombination losses

• BSF: p+ doped layer- Highly doped- Reduced

recombination

photon Back Surface Field

recombination

collection

EF

EC

EV junctionp-type p+-typen-type

18

Cell structure Losses in crystalline silicon solar cell

• Colour mismatch• Fundamental recombination

• Additional recombination- Impurities, defects, surfaces

• Shading• Reflection, absorption and transmission

- Absorption at the rear• Resistance• Non-ideal band gap

Crystalline Si solar cell: η=13-20%

Eband

generation

recombination

hν

η≤30%

19

Cell characterization

• Current Voltage (IV curve)- Open circuit voltage Voc

- Short circuit current Jsc

- Efficiency- Resistance losses

-10

0

10

20

30

-0.4 -0.2 0 0.2 0.4 0.6 0.8Voltage (V)

J (m

A/c

m2)

Rserie

Rshunt

standard

20

Cell characterization

• Internal Quantum Efficiency IQE- IQE=collected carriers / absorbed photons- Depth profile cell quality

0

20

40

60

80

100

300 500 700 900 1100

wavelength (nm)

IQE

(%)

Front side / emitter

Bulk /rear side

Rear side reflection

cell

light

21

Crystalline Si PV technology

• Feedstock- Effect impurities on cell output

• Wafers- Monocrystalline Si- Multicrystalline Si

• Cell technology- High efficiency with industrial in-line processing

• Module Technology- Module design integrated with cell concept- Simple interconnection and encapsulation

• Costs and environmental aspects

22

Crystalline Si PV technology

• Feedstock- Effect impurities on cell output

• Wafers- Monocrystalline Si- Multicrystalline Si

• Cell technology- High efficiency with industrial in-line processing

• Module Technology- Module design integrated with cell concept- Simple interconnection and encapsulation

• Costs and environmental aspects

23

Feedstock production

quartz, carbon mg-Si

solar grade Sisemiconductor

industry

semi-prime4500 ton/y

eg-Si

existing; 900.000 ton/y

under development, virtually unlim

ited

unde

r dev

elop

men

t, vir

tual

ly u

nlim

ited

existing; 26.000 ton/y

under development high cost

demand13.000 ton (2004)~200.000 ton (2020)

off-grade2000 ton/y

refining (silanes)

24

Feedstock production

• Direct route: SOLSILC process

• plasma furnace: SiC from pure SiO2 and pure Cpellets of SiC and SiO2 Si(L)

SiCSiO2

SiO+SiCSi+SiO2

CO

2Si+CO2SiO

Si(liq)

25

Feedstock: ingot growth

• Multicrystalline Siingot growth

26

Feedstock: effect impurities

segregation

contamination from crucible

dissolution evaporation from melt

Decreasing:[Oi]

Increasing:dopant conc. metal conc.[Cs]

small grain bottom

• Feedstock- Melting- Crystallization

• Ingot- Sawing

• Wafer

27

Feedstock: effect impurities

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01Fe

Al(tentative)

Ti

ppmw

waferingotfeedstock

85%

28

Feedstock: effect impurities

Impurities added to feedstock

0

5

10

15

20

25

30

35

0 20 40 60 80 100position in ingot (%)

J sc (

mA

/cm

2 )

clean reference ingot10 ppmw Ti and high O10 ppmw Ti and high Fe, C

Effect Ti and O on cell output clearly visible

29

Feedstock: effect impurities

Impurities added to feedstock• Ingot growth• Wafering• Cell processing• Characterization• Model development

- 1/Leff2∝1/τ ∝Cimp

- Segregationduring growth

- Solar cell modeling

• Needed to defineSolar Grade Si

1 10 1000.7

0.8

0.9

1.0

cell

effic

ienc

y (%

rel)

rela

tive

to h

igh-

purit

y fe

edst

ock

impurity concentration (a.u.)

14.5% cell techn. 17% cell techn.

our results:5 ppmw Al or10 ppmw Ti

reduction

Higher efficiency

30

Wafer technologies

liquid Silicon

planar liquid /solid interface

columnarcrystallised silicon

Inductive heating

inductive heating liquidsilicon

liquid / solidinterface

columnarcrystallised silicon

heating

heat sink

liquid / solidinterface

columnarcrystallisedsilicon

liquidsilicon (octagon)

liquid silicon

solid/liquidinterface plane

casting frame

Si foil

pulling speed speed ofsolid/liquidinterface plane

casting speed

Si foil

Vk

VZ

casting frame

Substrateliquid silicon solid/liquidInterface plane

Pulling of Single Crystals(Czochralski)

Casting of Silicon Blocks Bridgman Solidification

Heat Exchange Method Edge defined Film fed Growth Ribbon Growth on Substrate

heating

crucible liquid silicon

single crystal

31

Wafer technologies

• Multicrystalline Siingot growth

32

Wafer technologies

• From ingot tomc-Si wafer

33

Wafer technologies

• High quality monocrystalline Si material- Low impurity concentration- Low defect concentration- Higher efficiency (15-17% in industry, 20% pilot)- Higher costs per cell

• Lower quality multicrystalline Si material (mc-Si)- Higher impurity concentration- More defects- Lower efficiency (13-15% in industry, >16% pilot)- Lower costs per cell

• For both technologies: high sawing losses (about 50%!)

34

Wafer technologies

Edge defined Film-fed Growth(SCHOTT Solar)

String Ribbon

• Ribbon technologies(multicrystalline Si)

• Substrate growing andcrystallization in the samedirection

35

Wafer technologies

• ECN’s ribbon technologyRibbon Growth on SubstrateRGS

• Substrate growingperpendicular tocrystallization

Finished foils

AnnealingGassingCasting frame (cut)

Continuous substrate Preheating

Direction

36

Wafer technologies

Ribbons:• Better use of Si material (about factor 2)But• Lower initial material quality• Lower efficiencies

• EFG/SR: about 14% (industry)• RGS: about 13% (lab)- Very high throughput

Material PullSpeed

[cm/min]

Through-put

[cm2/min]

Furnacesper 100

MWEFG 1.7 165 100SR 1-2 5-16 1175RGS 600 7500 2-3

*[J. Kalejs, E-MRS 2001 Strasbourg]

37

Wafer Technology

RGS cell efficiencies using industrial process• Average efficiency 12.5%.• Current top efficiency 13%confirmed

• High efficiency lab processing 14.4%confirmed

• ~100 µm thin RGS wafer made• Efficiency around 11%• 2.9 g Si/Wp (nowadays ~10 g Si/Wp)

38

Cell processing

• Saw damage removal- Texturing for enhanced light coupling

(better efficiencies)• Emitter diffusion- Material improvement by gettering

• SiNx deposition as antireflection layer- Material improvement by passivation- Reduced surface recombination

(surface passivation)• Metallization- Ag front side- Al rear side (so-called Back Surface Field)

• Sintering for contact formation

39

Cell processingBatch processing• Wafers in carriers• Each process step well controlled• Used for high efficiency processing

etching junction ARC contacts

unloadload

transport

40

Cell processing

ECN’s inline processingHorizontal wafer transport on belts (wafer in; cell out)

• No wafer carriers• Large and thin wafers easier to handle (cost reduction)

etching junction ARC contacts

41

Cell processing

Examples from industryBatch processing BP Solar

In-line processing SCHOTT Solar

42

Cell processing

ECN Baseline process• Multicrystalline p-type Si• Acidic texturing / saw damage removal• P diffusion using belt furnace• Deposition of SiNx• Metallization (Ag front, full Al rear)• Simultaneous sintering both contacts

ResultsProcessing complete columns of wafersduring two years

• Average 16%• In industry about 15%

Wet chemical etching

Sintering contacts

43

TexturingAcidic texturing of mc-Si

Alkaline and acidic etch

44

TexturingAcidic texturing of mc-Si

cooler

inlet

etch bath

rinse

rinsedestaining

drying

outlet

exhaustsexhaustsHNO3 dripHNO3 drip

controllerbelt speedcontrollerbelt speed

45

TexturingAcidic texturing of mc-Si

• Lower reflection, higher efficiency- About 0.5% absolute

• Better appearance

46

TexturingSurface structure texturing Si

• Monocrystalline Si- Alkaline etching (NaOH or KOH)- Anisotropic etching

- (111) planes slowest etching rate- Pyramids on (100) substrates

• Multicrystalline Si- HF/HNO3 etching- Isotropic etching

- Random structure

47

Texturing Micro structureAlkaline etching of Si

Si + OH– + H2O SiO32– + H2 gas

• Higher concentrations and higher T- Almost isotropic etching- High etching rate- Used to remove saw damage (5-10 µm)- High reflectance (~30%)

Full size wafer

48

TexturingAlkaline etching of Si

• Lower concentrations and lower T- Anisotropic etching

- (111) planes slowest etching rate- Pyramids as texture on (100) substrates- Low reflectance (~10%)

- But, low etching rate

49

TexturingAcidic etching of Si

Mixture HF/HNO3

Oxidation3 Si + 4 HNO3 3 SiO2 + 4 NO gas + 2 H2O

Oxide removalSiO2 + 4 HF SiF4 gas + 2 H2O

• Obtained surface morphology depends oncomposition- Polishing- Defect etching- Texturing

50

Emitter processingNeeded to form p-n junction• Apply P source• Diffusion at ~900 C for about 10 minutes

• Depth about 0.5 µm• P concentration at surface: > 2×1020 cm-3

- Higher concentration neededfor good contacting

- However, it will result in additionalrecombination losses

Improved emitter/front side processing can give an efficiency gain of more than 0.5% absolute

15.0

15.5

16.0

16.5

1.00E+02 1.00E+03 1.00E+04 1.00E+05 1.00E+06 1.00E+07

emitter losses

effic

ienc

y (%

)

51

Emitter processingEffect dopant concentration on IQE• Improved blue response (up to 550 nm) for lower dopant

concentration• Higher Voc and higher Jsc: higher efficiency!

1E+18

1E+19

1E+20

1E+21

0 0.1 0.2 0.3 0.4depth in silicon [um]

atom

ic d

ensi

ty [c

m-3

]

barrierno barrier

0.4

0.6

0.8

1.0

350 400 450 500 550wavelength [nm]

IQE

20%15%10%5%0%

no barrier

Thicker diffusion barrier

52

Emitter processingAdditional effect of emitter processing

• So-called gettering- Diffusion of impurities to P rich layers (P-gettering)- Impurities will not affect efficiency in those P rich layers

• Improved bulk quality and, thus, higher efficiency

impurity

diffusion

53

SiNx depositionApplied using chemical vapour deposition• Low pressure chemical vapour deposition (only surface

passivation, ~700 C)• Plasma enhanced chemical vapour deposition

(different systems, ~400 C, 0.5-10 nm/s)• Sputtering (several nm/s)

Functions SiNx:H layer• Antireflection coating (70-80 nm)• Surface passivation (reduced recombination at the surface)• Bulk passivation (improved material quality)

- During anneal H diffuses into bulk and makes defects/impurities electrically inactive

54

SiNx depositionPlasma Enhanced Chemical Vapour Deposition (PECVD)• Parallel plate system

Direct plasma- Wafers as electrodes- Ion bombardment dependent

on plasma frequency- Damaged layer

• Remote PECVD- No ion bombardment

Aberle et al.

55

substrates

SiH4

NH3 or N2

MW plasma

SiNx depositionECN MicroWave Remote PECVD• Deposition rate about 1 nm/s

56

SiNx depositionExpanding Thermal Plasma (ETP)• Developed by TU/e• Deposition rate 5-10 nm/s• TU Delft: for thin film Si depositions

} cascade plates (4x)

anode plate

nozzle with NH3 injection

electrode

argon gas inlet

isolating plates

SiH4 injection ring

Ar/NH3 plasma expansion

Plasmabron

Expansie plasma

Substraat

57

SiNx depositionOptical specifications SiNx:H layer• Refractive index: n=2.1

higher n causes absorption at lower wavelength

• Ideal for air-Si: n=1.9; d=~80 nm• Ideal for air-glass-Si: n=2.3; d=~65 nm

(absorption SiNx too high)

• n can be tuned with gas composition• Higher n: more Si (SiH4)• Lower n: more N (NH3)

201 nnn =1

01 4 n

dλ

=

Air: n0

Si: n2

SiNx: n1; d1

58

SiNx depositionOptical specifications SiNx:H layer• Different layer thickness: different colour

59

Gettering and bulk passivation (emitter and SiNx:H)Improved bulk quality using gettering and passivation• Lifetime>100 µs will hardly affect cell efficiency (diffusion length 2

times cell thickness)• Besides higher efficiency, gettering and passivation will result in a

narrower efficiency distribution.

0

20

40

60

80

100

120

0 20 40 60 80 100position ingot (%)

lifet

ime

( µs)

initial

emitter and H passivation (SiNx:H)

emitter and double sided H passivation

12

13

14

15

16

17

18

1 10 100lifetime (µs)

effic

ienc

y (%

)1000

60

MetallizationScreen-printing process and sintering in belt furnace

61

MetallizationPrinciple screen-printing process• Metallization paste is ‘pressed’ through pattern in screen• Paste contains metal particles and oxides (etches Si at higher T)

Metallization line

62

MetallizationAg front side metallization• Fine line metallization printed through patterned screen

63

MetallizationFine line printing• Reduced shading losses• Contact resistance might be critical

emulsion line opening (∼100µm) fine line slumpingwire gauze

64

Metallization• Other techniques:

• Plating (electroless)

• Dispensing

• Pad printing

• Roller printing

65

MetallizationAl rear side (Back Surface Field to reduce recombination at surface)• After sintering step (around 800 C, few seconds) highly doped layer• Better BSF when thicker and higher doped

66

Efficiency ECN process

Results ECN Baseline processProcessing two complete columns (different ingots) of wafers during 2 years

• Average 16.0%• In industry about 15%

14.0

14.5

15.0

15.5

16.0

16.5

17.0

0 100 200 300 400position in ingot

effic

ienc

y (%

)

column 2004/5column 2005/6 Wafer size: 125x125 mm2

Thickness: ~300 µm

Material: p-type mc-Si

67

Efficiency ECN process• High-efficiency (17%) in-line process (300 µm thick; 156 cm2 mc-Si)

- 50 cells processed (best efficiency 17.1%; average 16.8%)- Module made using cover glass with ARC

Full area efficiency 14.8%; encapsulated cell eff: 16.8%

0

2

4

6

8

10

12

=<16

.5

16.5

16.6

16.7

16.8

16.9

17.0

>17.0

efficiency class

coun

t

VOC=22.2 V; ISC=5.76A; FF=0.738; P=94.3 Wp

68

Efficiency ECN process• From 2000 up to now

12.5

13.7

14.9

16

17

12

14

16

18

initi

al (<

2000

)

lifet

ime

BS

F

front

sid

epa

ssiv

atio

nan

d em

itter

light

man

agem

ent

Effic

ienc

y (%

) ECN 2005

0

20

40

60

80

100

300 500 700 900 1100wavelength (nm)

IQE

(%)

front side and emitter

bulk and rear side

rear side reflection

69

Future improvementsThin wafers• Rear side critical

Minority carrierdensity

• Combination ofgeneration andrecombination

17.0%: good bulk and rear15.9%: good bulk, low rear15.7%: low bulk, good rear15.3%: low bulk and rear14.3%: as 15.9%, but thin 0.0E+00

2.0E+13

4.0E+13

6.0E+13

8.0E+13

1.0E+14

1.2E+14

0 50 100 150 200 250 300Distance from front (µm)

dens

ity (c

m-3

)

15.7%15.3%15.9%17.0%14.3%Good bulk quality

Low bulk qualityGood rear side

li

Low rear side Thin cell

Front Rear

70

Future improvementAl rear side (Back Surface Field to reduce recombination at surface)• 17% reached on 300 µm thick wafersHowever:• Bowing for thinner wafers• Recombination losses too high for high efficiencies (>18%)• Internal reflection too low (~70%) for high efficiencies

71

Future improvements rear sideThin wafers• Rear side critical (bowing, reflection, BSF)• New rear side processing using for example SiNx

- Higher efficiencies for thinner wafers

SiNx for rear side passivationLocal rear contacts / BSF

15.0

15.5

16.0

16.5

17.0

0 100 200 300cell thickness (µm)

effic

ency

(%)

current rear sidefuture rear side

modelling

72

Future improvements rear sideThin wafers• New rear side processing using SiNx

- 16.4% obtained by ECN with baseline-like processing- About 1% absolute higher than reference with Al BSF

(obtained efficiency depends on Si material quality)

73

Future improvementsThin wafers (less dependent on material quality)• Improved light management

- Texturing- Light trapping

• Improved emitter (reduce losses)• Perfect surface passivation

- Both surfaces• Less metallization losses

- Series resistance (contact and line resistance)- Reduced shading losses

20% mc-Si cell efficiency should be possible! (long term)

74

Other industrial cell conceptsLaser Grooved Buried ContactsBP Solar• Monocrystalline

Rear side contacted cellSunPower• ~20%!• High quality

and expensivematerial

75

Other industrial cell conceptsSunPower• Cell 21.8%• n-type material• Module: full area 18.1%

Sanyo• HIT cell: 21.8%• n-type material• Emitter deposited

76

Record efficienciesMonocrystalline (4 cm2): 24.7%Monocrystalline (149 cm2): 21.5%Multicrystalline (1 cm2): 20.3%Multicrystalline (137 cm2): 18.1%

ECN multi (156 cm2): 17.0%Single layer ARC; homogeneous emitter; inline processing

Highest efficiency with completely inline processing

77

Module technologyConventional module technology (soldering)

Glass

EVA

Solar cells

EVA

Tedlar foil

Series connection

Interconnection strips (tabs)

78

Module technologyConventional module technology

interconnection lamination

79

Module technology

Pilot-line tabber-stringer for interconnection

80

Module technologyPilot line to be built at ECN

Fully automated and realibility-tested interconnection process for back-contact cells and suitable for thin and fragile cells

81

Module technologyNew module technology:• New cell designs needed

- Back contacted- Simple interconnection- Can be used for thin cells

MWT

MWA

EWT

PUM

82

Module technologyEmitter Wrap Through:• No metallization on the front• Thousands of holes

83

Module technologyECN’s PUM concept:• More energy from attractive cells• 2-3% less shading• Resistance losses independent

on cell size (only on size unit cell)• Standard cell processing except:

- Laser drilling holes- Junction isolation around holes

Mother Nature’s water lily

84

Module technologyECN’s PUM concept:• Single shot interconnection

and encapsulation

Single step module assembly

Glass plate

PUM cell

Rear side foil

Adhesive

85

Module technologyECN’s PUM process:• Foil preparation• Apply conductive adhesive

instead of soldering(lower stress)

• Pick and place cells• One step curing

and encapsulation

86

Module technologyECN’s PUM result:• Full size module (71×147 cm2)• 128 Wp (15.8% encapsulated

cell efficiency)• 0.6-0.8% absolute efficiency gain

Best PUM cell result up to now:• 16.7% (225 cm2)

At this moment PUM is the only integrated concept forcell and module

87

PV marketAnnual market growth more than 40%

Photon International, 2006

Growth rate 2004: 67%

2005: 1720 MWp (+44%)

Japan: ~50% market share

1992

1994

1996

1998

2000

2002

2004

ROWJapan

0200400600800

100012001400160018002000

MWp

PV Cell/Module Production

ROWEuropeUSAJapanTotal

88

PV marketMore than 90% crystalline Si technology

Photon International, 2006

40.8 37.4 34.6 36.4 32.2 36.2 38.3

46.2 52.5 55.8 56.2 61.5 58 55.2

13 10.1 9.6 7.3 6.2 5.9 6.5

0%10%20%30%40%50%60%70%80%90%

100%

1999 2000 2001 2002 2003 2004 2005Year

Tech

nolo

gy m

arke

t sha

re

thin filmmulti and ribbon Simono Si

89

PV marketExpected market: solar the most important primary energy source

PV and solar thermal power

Wissenschaftliche Beirat 2003

90

Costs PVContributes wafer is about 45%!Thinner wafers, or better ribbons, important!

Price solar electricity:0.20-0.50 €/kWh

(depending on location)

NL: ~0.50 €/kWh

9%

36%

30%

25%

sg-Siwafercellsmodule

91

Cost reduction PV• Less material use

• Thin ribbons• Less module materials

• High efficiencies for the same process costs• Advanced processing• New cell design

• Easy manufacturing• Automation• Easy module manufacturing

• High lifetime• Improved yearly system output

92

Cost reduction PV• Expected costs

012345

typischeturn-keysysteem-

prijs(€/Wp)

2004 2010 2020 2030 2050

jaar

BOSmodulesTypical

turn-key system price (€/Wp)

1000 GWp worldwide200 GWp in EU (200,000 jobs)

93

Cost reduction PV• Expected costs based on learning curves (EU project Photex)

- Combined effect of technology development, experience, ….- Progress ratio PR should be around 80%

Power Modules (1976-2001)

1987

1981

2001

1983

1990

1976

1

10

100

0 1 10 100 1000 10000

Cumulative Shipments [MW p] power modules (SU, 2003)

[2001 $]

Price of Power Modules (2001 $)

Estimate 1976 - 2001: PR = 80.0±0.4%

Estimate 1987 - 2001: PR = 77.0±1.5%

94

Cost reduction PV• Expected costs

• Solar competitivebetween 2010-2020

Source: RWE Energie AG and RSS GmbH

Photovoltaics

Utility peak power

Bulk power

0.0

0.2

0.4

0.6

0.8

1.0

1990 2000 2010 2020 2030 2040

€/kWh

900 h/a: 0,60 €/kWh

1800 h/a: 0,30 €/kWh

0.0

0.2

0.4

0.6

0.8

1.0

1990 2000 2010 2020 2030 2040

€/kWh

900 h/a: 0,60 €/kWh

1800 h/a: 0,30 €/kWh

Towards an Effective European Industrial Policy for PV.ppt / 05.06.2004 / Rapp @ RWE SCHOTT Solar GmbH

95

Environmental aspects• Energy Pay Back Time 2005

Energy Pay-Back Time (grid-connected, roof-top PV system;

irradiation 1700 resp. 1000 kWh/m2/yr)

0

1

2

3

4

5

ribbonS-Eur.

ribbonM-Eur.

multiS-Eur.

multiM-Eur.

monoS-Eur.

monoM-Eur.

Ener

gy P

ay-B

ack

Tim

e (y

r)

BOS

frame

laminate

96

Environmental aspectsEnergy Pay Back Time 2005 and 2010+

• Low energy consumption especially for Solar Grade Si• Low material use

(abundance)• High efficiency• High lifetime modules• Environmental friendly

processes• Recycling

0.00

0.50

1.00

1.50

2.00

2.50

3.00

ribbon11.5%

multi13.2%

mono14%

future ribbon15%

future multi16%

Ener

gy P

ay-B

ack

Tim

e (y

r)

BOSframelaminate

97

Conclusions• Solar Grade Silicon needed for growing market

- Effect of impurities on cell efficiency should be known• Less Si use with ribbons• Improved processing has led to 17% mc-Si efficiency using in-line

processing• New processes for thin wafers/ribbons under development• Integrated cell and module design like PUM needed• High module lifetimeThen• Cost reduction possible

- Will be competitive with bulk electricity price• Energy Pay Back Time can be reduced to <1 year• Solar energy will be the most important primary energy source in

2100

98

Applications at ECN

99

Applications

100

Thank you for your kind attentionThank you for your kind attention

FloriadeFloriade (2.3 (2.3 MWpMWp PV)PV)

Information / internshipInformation / internshipwww.ecn.nlwww.ecn.nlweeber@ecn.nlweeber@ecn.nl