Best Polysilicon Technologies Russ Hamilton

Best Polysilicon Technologies

11th China Solar PV Conference and ExhibitionRuss Hamilton 19.Nov.2010

•

•

•WAFER

•Crystalline Silicon

(Multicrystal-Si)

•Historically high manufacturing costs

•Substantial need

of high-purity silicon

• Highly technical production process

•THIN-FILM CIS-materials(CIS/CIGS)•Only thin-film technique equaling efficiency potential of multi-crystalline Silicon (20 %)

•Modification of material composition give room for continuous improvement

•THIN-FILM

•Cadmium Telluride

(CdTe)•Lowest manufacturing costs due to economy-of-scale (First Solar 2010: 1.4 GW)

•Severe concerns on various markets regarding environmental and health impact

•THIN-FILM Silicon Thin-film transfer•Today’s commercial products exhibit 6 – 7% efficiency in spite of 20 years of optimization

•High CAPEX per MW

•10 – 20 % efficiency degradation during first year of operation

•Maximum efficiencies achieved on laboratory cells•Source: Solar efficiency tables, Progress in PV, Vol. 18, 346-352 (2010)

MultiCr-Si CIS/CIGSe CdTe a-Si/µ-Si a-Si


19.5% 16.7%% 11.7% 9.5%


Material Efficiency Features

Monocrystalline Si solar cells 15 - 18 % Lengthy production procedure, wafer sawing necessary. Best researched solar cell material - highest power/area ratio.

Multicrystalline Si solar cells 13 - 15 % Wafer sawing necessary. Most important production procedure at least for the next ten years.

Polycrystalline transparent Si solar cells 10% Lower efficency than monocrystalline solar cells. Attractive solar cells for different BIPV applications.

EFG (Edge Defined Film fed Growth) 14% Limited use of this production procedure Very fast crystal growth, no wafer sawing neccesary

Polycrystalline ribbon Si solar cells 12% Limited use of this production procedure, no wafer sawing necessary. Decrease in production costs expected in the future.

Apex (polycrystaline Si) solar cells 9,5 % Production procedure used only by one producer, no wafer sawing, production in form of band possible. Significant decrease in production costs expected in the future.

Monocrystaline dendritic web Si solar cells 13% Limited use of this production procedure, no wafer sawing, production in form of band possible.

Amorphous silicon 5 - 8 % Lower efficiency, shorter life span. No sawing necessary, possible production in the form of band.

Cadmium Telluride (CdTe) Module6 - 9 % Poisonous raw materials, significant decrease in production costs expected in the future.

Copper-Indium-Diselenide (CIS) Module7.5 – 9.5 % Limited Indium supply in nature. Significant decrease in production costs possible in the future.

Organic 1.7% No power warranty.

Commercial PV Cell Efficiencies

Source: By Technology, Best Commercial Module Efficiencies, NREL, 03/2010

Characteristics of the BestPolysilicon Technologies:

Safe and reliable production at the lowest cash cost and highest quality

99.99999999+% SiliconLow Grade Silicon Such as

MG-Si

Impurities(Metals, Carbon, P&B)



Hydrochlorination TCS

Fluoride-based silane

(Silicones, Fumed silica)

FBR CVD Polysilicon

Siemens CVD PolysiliconTCS-based silane

TCS Siemens CVD Polysilicon

Direct chlorination TCS Non-polysilicon chemicals


Fluoride Based Silane Process

SilaneProduction

SilanePurification

PolysiliconFBR/Siemens

SolventRecovery

By-productDrying

Metal Alkyl

Production

SiF4

Production

Li/

Na

Al P

owd

er

H2

Polysilicon

CaF2

H2SO4

Si

Na(Li) /Al sulfate

Na(Li)AlF4

Na(Li)AlF4 inSolvent


• Polysilicon from silicon bearing precursor requires proximity to a phosphate fertilizer plant for H2SiF6 based process.

• SiF4 produced from H2SiF6 (proven) or from CaF2/NaAlF4 reacted with H2SO4 in a rotary kiln (in development)

• SiF4 reacted with metal (Na/Li) aluminum alkyl to produce Silane gas

• Silane is distilled for purity and polysilicon is produced by thermal decompsition of silane

• Among the lowest overall power consumption but• Large recycle streams of dilute sulfuric acid (for H2SiF6 process)• Development of CaF2/NaAlF4 process• 5:1 non-hazardous by-product to polysilicon generation (by weight)

Fluoride Based Silane Process

Direct Chlorination Based TCS Process

TCSProduction

PolysiliconSiemens Process

TCSPurificationSi

HCl

PolysiliconTCS

Production

Fumed Silica

STC StorageHCl

STC

STC

H2



Direct Chlorination Based TCS Process

• Direct Chlorination reactors have been used since at least the 1940s.

• Initially dominant demands were for the production of derivative silanes andfumed silica.

• Typically HCl and MGSi are reacted in a fluid bed reactor to produce TCS atapproximately 300 deg C and 2 to 4 barg pressure.

• STC recovered from the polysilicon reactors is used for fumed silica production.

• Very energy intensive process.

3HCl + Si SiHCl3 + H2 + Heat

SiCl4 + H2 SiHCl3 + HCl + Heat

Hydrochlorination TCS Based Technology

TCSProduction

Hydrochlorination

TCSPurification

CVDSiemens

Chlorides

Hydrogen

MG Silicon

STC

Waste Gas Recoveryand Recycle to TCS

(STC, H2, HCl, DCS)

Impurities Neutral/Safe Solids

Solar Grade Silicon（ Chunk or Rod）


STC, HCl, H2

TCS, H2

TCS-Silane based Siemens or FBR CVD

TCSProduction

Hydrochlorination

TCSPurification

CVDReactiveDistillation

(Silane)

Chlorides

Hydrogen

MG Si

Waste Gas Recycle(H2)

Solar Grade Silicon

(Chunk or Rod)

Impurities (Neutral/Safe Solids)


STC

Si+3HCl SiHCl3+H2 + Heat

SiCl4+H2 SiHCl3+HCl - Heat

Hydrochlorination (TCS ONLY)

Hydrochlorination (SILANE)

PRIMARY REACTIONS

Reactive Distillation CVD

2SiHCl3+H2 Si+SiCl4+2HCl+H2- Heat

4SiHCl3 SiH4 + 3SiCl4

(2SiHCl3 SiH2Cl2+ SiCl4) DCS

SiCl4+H2 SiHCl3+HCl - Heat SiH4 Si+2H2 - Heat

(2SiH2Cl2 SiHCl3+ SiH3Cl) MCS

SiH2Cl2+ SiH4) SILANE(2SiH3Cl


Which Polysilicon Technology is the best?


TCS Hydrochlorination/

Siemens CVD

Silane Hydrochlorination/

Siemens CVD

Silane Hydrochlorination/

FBR CVD

CAPEX BETTER WORSE BEST

HIGHEST QUALITY ELECTRONIC ELECTRONICMAYBE

ELECTRONIC

EASE OF OPERATION VERY GOOD GOODBEST

(SHOULD BE)

POWER CONSUMPTION(CVD Section)

BETTER(35-120 kwh/kg)

GOOD(40-120 kwh/kg)

BEST(10-15 kwh/kg)

POWER CONSUMPTION(MG Si to E.G POLYSILICON)

BEST (70-155 kwh/kg)

WORSE (90-115 kwh/kg)

BEST (70-90 kwh/kg)

O &M STAFF HIGHER HIGHER LOWER

ROBUST PROCESS GOOD GOOD BETTER

R&D REQUIRED NO SOME SOME

RISK LOW HIGHER HIGHER

The Best Polysilicon Technology Must:

• Fit your Business Plan;

• Low Operating Cost with Highest Quality; and

• Safe, Environmentally Sound and Reliable Operation; and

• Overall Facility Integrated Processes for Lowest Energy Consumption and Maximum Waste Recovery; and

• Capable of Under $20/kg Fully Loaded Cost; and

• Have Access to Competitive Raw Materials and Labor; and

• Need Low CAPEX Facility Cost; and

• Remember there are a few best technologies but lots of mistakes available to select from.


Best Polysilicon Technologies Russ Hamilton

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