Manufacturing Polysilicon
PV world is dominated by crystalline silicon production including cast and ribbon silicon, films
makes up around 10% of the present market of around 3Gw/year at $3/watt at $300/kg
polysilicon.
Futuristic manufacturing Cost analysis:
If we take cost of Polysilicon to be 70$/kg (long‐term agreements already signed) and
manufacturing cost of the module to be 2.11$/Watt then,
Cost components:
 Wafer cost is 1.08$/watt. This reflects the importance of the cost of the polysilicon.
 Processing the wafer into cell costs 0.40‐0.45 $ /watt. The cell efficiency has a big role
to play. Taking a realistic cell efficiency of 16% to achieve a module cost of around
2$/Watt. If the efficiency goes up further the cost reduces to below 2$/watt for module
 Processing the cell into module costs 0.40‐0.45 $ /watt. We choose the yield ( efficiency
of conversion of cells into wafers ) as 85% as at this percentage cost of module is
approached. If we are able to increase this yield to say 90% then the cost will reduce
further.
So for 50Mw/year of production the three major cost component comes as
• Wafer 1.08$/watt
• Wafer to cell conversion 0.40‐0.45 $/watt
• Cell to module conversion 0.40‐0.45 $ /watt
More than 90% of the cost is material cost. Other costs involved are Sg&A, labour, overhead,
and plant depreciation (at around 10%).
Future scenario: Lets consider we build large solar farms of polysilicon modules and reduce the
cost by building an onsite building block factory, where the products goes straight to
deployment in a range of a few meters
Now if we build, say 100MW /year factory to construct Solar farms with a module of 1Kw
capacity, the size of the module be about 3meters * 12 meters (36 square meters of area).
This size brings economies of scale and significant savings
1) cost of the module itself goes down as it is bigger thus less polysilicon
2) Less framing material
3) Less busing material
The other savings in cost are
i) reduced labour for module assembly
ii) reduced power wiring
iii) less balance of systems
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This can achieve a final cost of around 2.87$/watt in Germany and USA and other developed
countries but in developing countries like India with less labour cost, manufacturing cost,
reduced overhead the cost would be around 30% less that is 2.01 $/watt.
Growth of the market, Present: 45%/year, Future >45%.
USA is picking up on the race
India is growing more rapidly because of customized government incentives and tax breaks
Germany will be steady in its growth
Market by 2010
8‐10 Gw/year of manufacturing
6 major manufacturers each producing 1Gw or more
30 smaller manufacturers each producing 100MW or less
Modules selling at a price of around 2.90$/watt, which allows margins for the industry
80% of PV modules will be either mono or polycrystalline
20% Thin films modules
Investment:
Basic machines:
1) Cell testing machine: These machines sort incoming cells as even one defective or
underperforming cell drags down the efficiency of the whole module as the cells are
placed parallel in circuit. These machines tests around 5 million cells/ year. Throughput
has to be increased to achieve cost efficiency at least by a factor of 5.
2) String Assemblers: This machine solders the cells together.
3) Laminators: Machine laminates the module with material to increase its absorption
capacity
Cost of the factory on different equipments
i) wafer equipment ~ 0.60$/watt
ii) cell equipment ~ 0.40$/watt
iii) module equipment~ 0.30$/watt
So this adds up to 1.30$/watt base manufacturing cost
Taking these into account at current prices the capital Investment required for different
types of plants for minimum feasible size are estimated below
1) Polysilicion manufacturing: $250million for 50Mw/year
2) Wafer production plant : $30‐40 million for 50 Mw/year
3) Solar cell factory : $10 million for 20Mw/year
4) Module assembly plant : $ 2‐3 million for 10Mw/year
Future Trends:
1) Thinner wafers to reduce raw materials cost
2) Increased usage of backside contacts as front side contacts blocks sunlight by 5%
3) Module glue strength and effectiveness which impacts efficiency
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Bibliography
The Minto pyramid principle by Barbara Minto, 2003
Crossing the divide‐A CERA Multiclient Study, CSP and PV technologies, 2007
http://www.rnp.org/renewtech/tech_solar.html
http://www.nrel.gov/csp/maps.html
http://www.nrel.gov/csp/troughnet/solar_data.html
http://www1.eere.energy.gov/solar/csp.html
http://www1.eere.energy.gov/solar/solar_glossary.html#photovoltaic_array
http://www.youtube.com/watch?v=kLSARSw2JUQ&feature=related
www.mnes.gov.in
World energy outlook 2007
Renewable Energy World magazine (issues: May, 2007 to July 2008)
www.renewablenergyworld.com
BSW solar (German solar energy association) www.solarwirtschaft.de
www.tatabpsolar.com
www.acciona‐energia.com
www.solarbuzz.com
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