Polysilicon

Ultra-pure silicon (nine to eleven nines) made from metallurgical silicon; the base of solar wafers and chips, over 90% made in China.

Specialty chemicals · Energy-transition chemicals · No. 69

• Product family
• Feedstock: Minerals and salts
• about 1.4 Mt produced in 2025 (derived: China 1.32 Mt, down 28.4% from 2024, plus roughly 0.1 Mt outside China, indicative); world output was about 1.95 Mt in 2024; nameplate capacity above 3.2 Mt
• 35.0 t CO₂e per t
• HS 280461

Solar panels start as silicon purified to nine nines, and China built enough plants to make it twice over.

Chart: Illustration: Polysilicon

Where it comes from

Chart: Map of where it comes from

Silicon metal from quartz is turned into trichlorosilane gas, distilled, and deposited back as silicon on hot rods at about 1,100 C.

Three things to know

1. About 94% of polysilicon goes into n-type solar wafers; chips take only about 4% but need even purer, 10-11 nines material.
2. Siemens reactors burn about 48 kWh per kg, while newer fluidised-bed granules need only 11-20 kWh.
3. India makes no polysilicon, yet ALMM-listed domestic wafers become mandatory for covered projects from 1 June 2028.

The journey

1. 1 QuartzReduced with carbon in arc furnaces
2. 2 Silicon metal98.5-99.5% pure metallurgical silicon
3. 3 TrichlorosilaneReacted with HCl, then distilled ultra-pure
4. 4 DepositionGrown on hot rods or granules
5. 5 PolysiliconNine to eleven nines pure
6. 6 WafersSliced for solar cells and chips

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