Presentation KAUST distribution

KAUST Solar Future

Nov. 2015 B. CeccaroliMARCHE AS 1

SILICON FEEDSTOCK:

silicon processes and

products for solar industryBruno Ceccaroli

90% of PV-systems are built on crystalline silicon

2

Fraunhofer Institute for Solar

Energy Systems ISE:

Photovoltaics Report

Freiburg, 24 October 2014

KAUST Solar Future

Nov. 2015 B. CeccaroliMARCHE AS

Outline

• Solar cell materials and their availability

• Metallurgical grade silicon (MGS): Manufacture, applications,

cost and price

• Solar grade silicon (SGS): Processes, products

• Product differentiation: by shape, purity and cost

• SGS industry trends: supply-demand

• Conclusion

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SECTION 1

Solar cell materials and their availability

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About Silicon

The EARTHS crust

consists of 27% Silicon

• Occurs in nature in tretavalent state, as

silicate and silica.

• Natural element, 27% of the earth crust,

second largest element after oxygen

•Identified in 1810 by Berzelius (Gay-

Lussac, Thénard)

• First produced by Sainte-Claire Deville

(1853) by electrolysis of an

aluminosilicate melt

•Industrially metallurgical grade silicon

(99,9%) may be produced in millions of

tonnes

http://www.realscience.org/graphics/earth.gif

http://www.realscience.org/graphics/earth.gif

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Fortunately Silicon is an Abundant Natural

Resource

0.001

0.01

0.1

1

10

100

1000

10000

100000

1000000

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000 10000 100000 1000000

Ru

Pt TeIn

SeAu

Ag Cd

Cu

Zn

Ni

Pb

Fe

REE

Si

Al

V

Co

Li

GaGe

World primary

refinery production

(g/capita/yr)

Average abundance in the continental crust (ppm)

Rare, scattered and minor metals

Courtesy of B. Andersson Sandén

SECTION 2

Metallurgical grade silicon (MGS):

manufacture, applications, cost and price

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Manufacturing Metallurgical Grade

Silicon (MGS)

Courtesy of Silicium Bécancour

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Metallurgical grade silicon

MGS has been produced in

large electrical arc furnaces

since 1905.

Source: A. Schei et al. ELKEM

SiO2 + C = Si + 2 CO

Manufacturing Metallurgical grade Silicon

(MGS)

Si (Silicon)SiO2 (Quartz)

+ =

C (Carbon) and Power

SiO2 + 2C = Si + 2 CO

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Courtesy

Prof. Gabriella Tranell

MGS Commercial Usage

11

Aluminum Alloys Polysilicon to electronics Silicones Photovoltaics

Byproduct:

Silica fume

Courtesy Jan Ove Odden

MGS Market Segments

Total market 2015: 2,5 million

metric tons

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Courtesy Prof. G. Tranell

According to CRU Global solicon demand will

continue to grow at 5,9%

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Current silicon production is relatively

concentrated in China, USA/Canada, Norway,

EU(France/Spain), Brazil

China has increased its share to 65-70%

between 2010 and 2015:Domestic consumption is increasing on

expense of export

New comers:Iceland, Middle East, Malysia

Plant locations determined by:

(Historical) cost conditions:

Access to inexpensive electricity

Fiscal, trade and environmental policies and

regulationsChina

57 %

EU

8 %

USA

7 %

CIS

3 %

RoW

8 %

Brazil

10 %

Norway

7 %

Silicon production by country/region 2011

Data: CRUKAUST Solar Future


15

Major price change after 2008

Price range EU-US: 1-2 $/t before 2008; 2,5-3,5 $/t after 2008

SECTION 3

Solar grade silicon (SGS):

Processes, products

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SGS specifications – SEMI Standard: ppm and

ppb level needed vs. % level in MGS

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category units I II III IV

Acceptor

(B, Al)

Donor

P, As,Sb

Carbon C

Transition

Metals

Alkali(alkal

i earth

metals

ppba

ppba

ppma

ppba

ppba

<1

<1

<0,3

<10

<10

<20

<20

<2

<50

<50

<300

<50

<5

<100

<100

<1000

<720

<100

<200

<4000

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MGS is not pure enough to produce solar cells:

further refining is needed

Chemical composition of commercial MG silicon

Quality of the produced MG-Si is a

function of the raw materials used

in the production

Source: A. Schei et al. ELKEM

Chemical vs. metallurgical route

• Developing industrial large scale and cost efficient processes

to solar grade silicon remains a high priority

• There are two main avenues:

– Metallurgical route: purification of elementary silicon in the liquid

or solid phase

– Chemical route: purification by fractional distillation/condensation

of a volatile silicon bearing compound

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2015 B. CeccaroliMARCHE AS 19

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Silane plant at REC Silicon

Moses Lake (WA) and Butte (MT)

The chemical route has been the

traditional approach to purify silicon for

solar cells

Trichlorosilane and monosilane are the only

volatile compounds commercially used to

produce polysilicon

• Established process, current market leader

• Generate by-products containing chlorine

SiHCl3 + H2 Si + 3HCl

SiH4 Si + 2H2

• Hydrogen is the only chemical by-product

• Homogeneous decomposition of silane generates silicon powder

21

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Two silicon volatile melecules, two types of

reactor Three well proven commercial

processes



TCS

(SiHCl3)

Silane

(SiH4)

Siemens

hot

filament-

rod

X X

Fluidized

Bed

Reactor

X

“Siemens” Process• ”Bell jar” reactor

• Silicon filaments or slim rods made

in specific/separate growth process

(e.g. FZ)

• Filament connected to electrical

graphite conductors

• 2 power input systems and

preheating of the filament

• Increasing power input and gas

adjustment along the growth

• Massive heat loss through cooling

of reactor wall

• Gas silicon precursor: SiHCl3 or

SiH4

• Batch/cycle time: 60-150 hr

• Post-deposition process:

harvesting, crushing

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B. CeccaroliMARCHE AS 23

Courtesy of REC Silicon

Fluidized Bed Reactor

• Ascending flowing gas

percolates through the particle

bed

• At a certain flow rate particles

begin to lift making the bed

behave like a fluid

• Large degree of temperature

uniformity uniform CVD

• Control parameters: particle

density, size distribution, bed

heigth, gas flow, pressure

• As particles grow, the heaviest

particles need to be removed

and replaced by smaller ones

(”seeds”) to keep the bed under

steady state

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B. CeccaroliMARCHE AS 24

Silicon Return

Exhaust H2,unreacted

silane and elutriated fine

nano-silicon

Heated

H2Silane

Silicon

granules

X

X

Metallurgical purification of silicon –

upgraded MGS• Raw material selection

• Carbothermal reduction

• Metallothermal reduction

• Two or three phase purification system involving molten (liquid) silicon (pyrometallurgical processes in ladle or reactor)

• Liquid-Liquid (solid) extraction: Slag treatment

• Liquid- Gas extraction: Gas treatment.

• Two phase purification involving solid state silicon

• Leaching (hydrometallurgical processes, low temperature)

• Alloying (pyrometallurgical processes, high temp.)

• Solid state refining

• Crushing

• Classifying (dry or wet)

• Phase transfer

• Crystallization

• Zone refining

• Electrolytic transport

25

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Comparison by output: TCS/Siemens by far the dominant

technology; silane/FBR may be ~20% of total capacity by

2018; UMG remains marginal (5%?)

26

Gøran Bye | ©AMMS | Polysilicon Market Update | 16 March 2015

-

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

450,000

2012 2013 2014 2015 2016 2017 2018

MT

pe

r Y

ear

Taking existing capacity - operating and idled - and known ongoing expansion initiatives into account, TCS/Siemens will still be the dominant technology in

2018, but Silane/FBR is posed to double its share of the market(REC/GCL/SUNE volumes @ face value)

Silane/FBR (MT/y)

TCS/Siemens (MT/y)

Sources: AMMS estimate based on industry and company announcements and analyses

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SECTION 4

Product differentiation: by shape, purity and cost

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Silicon products from “Siemens”

Reactors

Silicon products from FBR



Silicon Return

Exhaust H2,unreacted

silane and elutriated

fine nano-silicon

Heated

H2Silane

Silicon

granules

X

X

Silicon products from metallurgical routes –

may take various shapes

30

• Flexible form factors

• Dependent on last step in

purification process and

customers’ requirements

• Lumps

• 5mm – 200mm pieces

• Granules/chips

• 0.5mm – 10mm

• Bricks

• Sawn from ingots

• Different sizes

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Differentiation by purity

Impurity Siemens (Solar)

(value range)

FBR

(value range)

U-MGS

(value range)

P (donor)

B (acceptor)

Total metals

C

O

Gas inclusion

0.3-5 ppba

0.1-5 ppba

20-50 ppbw

0.25-1 ppma

0.5-5 ppmw

0.3-20 ppba

0.3-20 ppba

30-1,000 ppbw

0.5-10 ppma

10-100 ppmw

H2

300-1,000 ppba

500-2,000 ppba

100-1,000 ppbw

50-200 ppma

(100 ppmw)

• Higher Metal concentration affects life time minority charge carriers lower cell

efficiency

• Oxygen form pair with B affects Light Induced Degradation (LID)

• Oxygen, Carbon, metals form inclusions which may destroy single crystal structure

(CZ)

• High dopant (B, P) concentration compensation reduced material yield risk of

LID risk of reverse current breakdown

31

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Side by side – total energy consumption

32

• Solar grade silicon manufacturing consumes

large amounts of energy that negatively

impacts both silicon economics, energy pay-

back time and carbon emissions of PV

• Focusing on the power consumption only

will omit the significant need for thermal

energy that is delivered by burning natural

gas, diesel, or coal

• In many geographies the access to, and the

pollution from, power generation and

feedstock for thermal energy is

unsustainable and costly

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Side by side – what really matters is total cost

33

Best In Class

TCS/Siemens HC,

existing/

debottlenecked

TCS/Siemens HC greenfield, PRC ?

Best In Class

uMGS existing

Most advanced uMGS greenfield,

PRC ?

Best In Class

SiH4/FBR already

existing

SiH4/FBR

greenfield, PRC ?

-

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170 180

190

200

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Ca

pit

al E

xp

en

dit

ure p

er K

ilo

gram

Ca

pa

city

(U

SD

)

Variable cash cost of production, finance cost & maintenance; but excluding SG&A

(USD/Kg)

USD 27.50 per KilogramUSD 22.50 per KilogramUSD 17.50 per KilogramUSD 12.50 per Kilogram

Cost lines assume:10 years' straight line depreciation; maintenance expense = 4% of initial capex; financial cost = 4% of 50% of capex

Sources: Industry announcements; REC presentation dated May 17, 2012; Elkem Solar; AMMS estimates

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SECTION 5

SGS industry trends: supply-demand

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The polysilicon industry is indeed (re-)consolidating: three

capacity tiers emerge towards 2018

35

-

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

2012 2013 2014 2015 2016 2017 2018

MT

pe

r Y

ear

From"Big Four" & "Next Six"

to"Big Two", "Medium Three"

& "Next Five" ?

"Others"

TBEA Xinte Silicon

DAQO New Energy

LDK Silicon

SunEdison

Tokuyama

Hemlock Semiconductor

REC Silicon

OCI Company

Wacker Chemie

GCL Poly

Sources: AMMS estimate based on industry and company announcements and analyses

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Supply/demand balance in 2014–16 (US$ 5.5-7bn global

market); net new capacity needed from 2017 and onwards

36

Gøran Bye | ©AMMS | Polysilicon Market Update | 16 March 2015

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Final remarks, conclusion

• Crystalline silicon remains the dominant PV technology

• Solar grade silicon is fragmented in at least three categories of

products: Siemens polysilicon, FBR polysilicon and UMG silicon.

• Although more expensive and energy consumming Siemens

polysilicon is by far the main feedstock. FBR is increasing, UMG

silicon exhibits a great potential but remains marginal

• SG silicon’s offer is currently exceeding the demand resulting in low

prices. But continued growth of PV calls for more capacity from 2017

and onwards

• SG silicon is capital and energy consumming offering reward

opportunities for those affording both capital and cheap energy

• MG Silicon is the raw material common for all solar grade silicon (one

exception). It is also capital and energy consumming. It’s a not

replaceable raw material not only for PV and semiconductors but also

for aluminum alloys and silicones. With current pricing MGS offers

good return on invested capital and should be considered as

investment target.



For more details consult

• Handbook of Photovoltaic Science and

Engineering

Edited by ANTONIO LUQUE, IES, University

of Madrid and STEVEN HEGEDUS, University

of Delaware, USA. John Wiley & Sons Ltd,

2003

2nd edition, 2011, Chapter 5: Solar Grade

Silicon Feedstock by Bruno Ceccaroli & Otto

Lohne

• Gøran Bye and Bruno Ceccaroli,

Solar Grade Silicon: Technology Status and

Industry Trends, presented at Silicon Materials

Workshop, Rome, Oct. 7-8, 2013; published in

Solar Energy Material & Solar Cells (Elsevier,

2014) pp. 634-646.

THANK YOU FOR YOUR ATTENTION

Particular thanks to Göran Bye, Alan Crawford,

Jorn De Linde (CRU), Gabriella Tranell (NTNU), Jan

Ove Odden (Elkem) for invaluable advice and

sharing information.

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