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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
Best Polysilicon Technologies
19.5% 16.7%% 11.7% 9.5%
Best Polysilicon Technologies
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)
Best Polysilicon Technologies
Best Polysilicon Technologies
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
Best Polysilicon Technologies
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
Best Polysilicon Technologies
• 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
Best Polysilicon Technologies
Best Polysilicon Technologies
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)
Best Polysilicon Technologies
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)
Best Polysilicon Technologies
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
Best Polysilicon Technologies
Which Polysilicon Technology is the best?
Best Polysilicon Technologies
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
Best Polysilicon Technologies