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Impact of Materials Prices on Cost of PV Manufacture – Part I (Crystalline Silicon)

Nigel Mason SMEET II Workshop, London 27 Feb 2013

content

Brief introduction to Solar PV Technologies

Part I - Crystalline Silicon Case Study 1 - Silicon Silicon production, consumption, price, cost reduction and impact Case Study 2 - Silver Usage in PV, silver demand & price, alternative technology Part 2 - Thin Film to be resented by Chiara Candelise Conclusions

2 Candelise & Mason / SMEET II 27Feb13

technology platforms

flat-plate

Candelise & Mason / SMEET II 27Feb13 3

sun-tracking concentrator

mono-crystalline

multi-crystalline

silicon ribbon

a-Si / c-Si

CdTe

CIGS

DSC

Polymer OPV

SM-OPV

Thin Film Emerging Crystalline Silicon

technology status


Thin Film a-Si/ c-Si CdTe CIS/CIGS

Best lab cell efficiency 13% 19% 20%

Commercial module 7-10% 9-13% 10-14%

Emerging DSC Polymer SM-OPV

Best lab cell efficiency 12% 11% 12%

Today’s module eff. 3-5% 3-5% -

Wafer-Based Silicon Mono c-Si Multi c-Si

Best lab cell efficiency 25% 20%

Commercial module 15-20% 14-17%

market share & trend


0%

20%

40%

60%

80%

100%

19

99

20

00

20

01

20

02

20

03

20

04

20

05

20

06

20

07

20

08

20

09

20

10

20

11

ma

rke

t S

ha

re

a-Si

CIS

CdTe

ribbon-Si

multi-Si

mono-Si

88% of PV production (2011) is wafer-based crystalline silicon technology (c-Si)

Market share of c-Si technology >80% for past 13 years

Source: Photon International

mono-Si31%

multi-Si57%

CdTe6%

CIS2%

TF-Si3%

Output byTechnology (2011)

c-Si PV value chain

6

MG Si Polysilicon Crystal Wafer Cell Module

Candelise & Mason / SMEET II 27Feb13

Case Study 1 – Silicon

polysilicon production

7

Carbo-thermic reduction of

quartz Si + HCl = SiHCl3

Fractional distillation SiHCl3

Reduction in H2 to Si

Metallurgical Grade Si

Siemens process for semiconductor grade Si (polysilicon)

cost ~$2/kg ~$20/kg


300,000 MT/year

Pre-2005 PV industry used scrap Si from semiconductor industry at price ~$20/kg

Around 2005 PV consumption of polysilicon matched semiconductor industry where price ~$50/kg

Rapid growth in PV 2005-2008 exceeded supply and spot price increased to $500/kg at peak

Subsequent expansion in polysilicon production has resulted in excess supply and price fall to ~$20/kg

silicon price


42%55% 58%

68%80%

88% 92% 94%

58%45% 42%

32%20%

12% 8% 6%

2005 2006 2007 2008 2009 2010 2011 2012

PV share of polysilicon outputPV electronics

0

50

100

150

200

po

lysi

lico

n p

rice

($/k

g)

Solar-grade silicon price trend

PV cost reduction


The actions

Before the Si price spike the PV modules cost was ~$4/Wp of which ~$1/Wp was the silicon cost

The industry response was to reduce Si consumption from 15 g/Wp to 5 g/Wp by

• Thinner wafers • Reduced kerf loss • Higher yields • Increased recycling • Higher efficiency

At the same time the polysilicon industry significantly increased capacity (3-year lead-time)

Temporary increase in module price 2005-2010

Silicon cost in PV module reduced from $1.00 to $0.20/Wp

and c-Si remains cost-leading technology * Spot price for c-Si module in Germany week 8/2013 was €0.53/Wp ($0.70/Wp)

The outcome

Sou

rce:

IREN

A R

enew

ab

le E

ner

gy

Tech

no

log

ies:

Co

st A

na

lysi

s, S

ola

r P

V 2

01

2

*

Case Study 2 – Silver

used for electrodes (contacts)

Electrical contacts are made to the top and bottom surfaces of the silicon cell

These contacts are used to interconnect cells in a module and carry current to external circuit

Silver-loaded paste is screen printed on the silicon and heated to 780°C to form Ohmic contact to silicon

Silver is not detrimental to cell performance, is inert to firing temperature and produces a surface to which metal ribbon can be readily soldered.


silver - cost challenge

Remarkable reductions in PV module cost have been achieved over recent years

but rising silver metal price has limited cost reduction in cell fabrication

Best-practice wafer-to-cell conversion cost <$0.20/Wp

Typical silver paste cost $0.09/Wp

11

module

silicon

wafer

process

silvercell

module cost breakdown

paste consumption ~300 mg/cell156mm

silver cost $ 1.10/g silver cost in wafer $ 0.33/cell ($0.09/Wp)


-

5,000

10,000

15,000

20,000

2008 2009 2010 2011e 2012e 2013e 2014e 2015e

Industrial Demand for Silver other

ethylene oxide

solder & brazing

electrical & electronic

PV

MT

sliver demand

• Industrial demand for silver 55% of supply

• Prime industrial use is electrical & electronics

• PV consumes around 6% of demand but increasing with market growth

• No shortage of silver but supply driven by mining and price

12

-

5,000

10,000

15,000

20,000

25,000

30,000

coins & medals

silverware

jewelry

photography

industrial

demand (2010)

-

5,000

10,000

15,000

20,000

25,000

30,000 net gov. sales

recycle

mine production

supply (2010)

MT

sou

rces

: Th

e Si

lver

Inst

itu

te P

R 7

Ap

r 2

01

1 a

nd

Ph

oto

n In

tern

ati

on

al 8

-20

11


base metal alternatives

Nickel plated contacts were used in PV cells in the early 80’s by Solarex and Motorola

Requires on-cell mask (e.g. photolith.) for electroless Ni deposition

Oxidation of nickel and copper limit their use in printed and fired pastes

Copper an ideal conductor (92% conductivity Ag) but a detrimental impurity in silicon

2-layer Ni/Cu offers an effective solution

13

Ni plating of solar cells - US DoE/JPL funded work April 1980


Ni/Cu/Sn plate v Ag print

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Attribute Ag Screen Print Ni/Cu/Sn Plating

Lower material cost Ag price $1200/kg Cu price $9/kg

Narrow line width 50-120 m 20-40 m

Lower Resistivity 3-10 Ω.cm 1.7 Ω.cm

Lower contact resistance sensitive to firing temp. <1 mΩ.cm2

Higher aspect ratio (h:w) Range 1:10 to 1:2 1:2 or better

Lower firing temperature 750-800 C 350-400 C


Laser pattern SiN

Ni plate

350°C sinter Ni-Si

Cu plate + Sn cap

Screen Print Ag paste

780°C fire-through SiN

Copper - more complex process but lower cost and improved performance

early adopters (of Cu)

15

Source: Ji-sun Kim (Shinsung Solar) et al., PVSC 2011

In production today

Pilot production or R&D


Pioneered by

summary (from case 1 & 2)

A 3-fold decrease in Si consumption

per Wp and a 2-fold decrease in Si

price has driven c-Si to a low price

High silver price is driving a range of

short-term silver paste-reduction

initiatives but copper-based

contacts provide a long-term

solution to sustainable cost

reduction

16 Candelise & Mason / SMEET II 27Feb13

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

Dec-08 Dec-09 Dec-10 Dec-11 Dec-12m

od

ule

pri

ce ($

/Wp

)

Factory-gate c-Si module prices

Message

Incumbent industries will find innovative ways to overcome

material shortages or price escalation

Source: Photon Consulting

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