Metallurgical-Grade Silicon (MG-Si): The First Step From Quartz to a Solar Wafer

Where the silicon in a wafer really starts

Every solar wafer traces back to quartz. Before silicon can be purified into polysilicon, grown into an ingot and sliced, it has to be freed from oxygen. That first step produces metallurgical-grade silicon, usually shortened to MG-Si and traded as silicon metal.

It is an industrial commodity, not an electronic material. PVEducation describes MG-Si as about 98% pure, with a wider range of 98–99%, and used extensively in the metallurgical industry. Our Siemens-process guide covers what happens next; this guide covers the step before it.

• Quartz → MG-Si (this guide)
• MG-Si → polysilicon (Siemens or FBR route)
• Polysilicon → ingot → wafer → cell → module

How it is made: quartz, carbon and an arc furnace

MG-Si is made by carbothermic reduction: silica, in the form of quartz or quartzite, is reduced with carbon in an electric arc furnace using carbon electrodes. PVEducation gives the furnace range as 1,500–2,000 °C and names coal and charcoal as reducing agents; a silicon metal supplier, Westbrook Resources, puts the main reaction zone above 1,800 °C.

The simplified reaction is silica plus carbon giving silicon and an oxide of carbon. In practice the furnace is a continuous, power-hungry smelter, and the quality of what comes out depends heavily on what goes in. PVEducation notes that impurity levels vary widely with process variation and with the silica and carbon raw materials used.

• Feed: quartz or quartzite plus carbon reductants (coal, charcoal)
• Furnace: electric arc, carbon electrodes, reaction zone above ~1,800 °C
• Output: liquid silicon tapped and cast, then crushed and sized

What the grade codes 553, 441 and 3303 mean

Silicon metal is usually sold by a short code that lists maximum impurities in a fixed order: iron, aluminium and calcium. Westbrook Resources gives 553 as at most 0.5% iron, 0.5% aluminium and 0.3% calcium; 441 as 0.4%, 0.4% and 0.1%; 3303 as 0.3%, 0.3% and 0.03%; and 2202 as the cleanest common grade at 0.2%, 0.2% and 0.02%.

These codes describe metallurgical cleanliness, not electronic purity. Even the cleanest grade carries far too much boron and phosphorus for a wafer. PVEducation puts boron and phosphorus in MG-Si at hundreds of parts per million by weight, which is why chemical purification through polysilicon is unavoidable for solar and chip use.

• 553: Fe ≤ 0.5%, Al ≤ 0.5%, Ca ≤ 0.3%
• 441: Fe ≤ 0.4%, Al ≤ 0.4%, Ca ≤ 0.1%
• 3303: Fe ≤ 0.3%, Al ≤ 0.3%, Ca ≤ 0.03%
• 2202: Fe ≤ 0.2%, Al ≤ 0.2%, Ca ≤ 0.02%

Solar is only one of its customers

Most silicon metal never goes near a solar panel. USGS describes the main consumers as aluminium alloy producers and the chemical industry, especially silicones, with a share further processed into semiconductor- or solar-grade polysilicon. Westbrook Resources describes aluminium alloying, for example lighter automotive parts, as the main application.

This matters for anyone planning polysilicon. A domestic polysilicon plant would compete with aluminium and silicone makers for the same feedstock, and polysilicon producers usually specify tighter impurity limits than the standard commercial grades. In the United States, silicon was added to the federal list of critical minerals in November 2025, according to USGS, a sign that the commodity is being treated as strategic rather than routine.

• Aluminium alloys: largest single use
• Chemicals: silicones and other silicon compounds
• Polysilicon: for solar and semiconductors

Global supply is concentrated

USGS's February 2026 Mineral Commodity Summary estimates that China accounted for almost 80% of global production of silicon materials in 2025, and lists China's silicon metal output at about 4.0 million tonnes for that year. Brazil, Norway, France and Australia follow at much smaller volumes.

The same summary reports that US silicon metal prices fell sharply in 2025, which it attributes to oversupply, weak aluminium and silicon demand and available polysilicon stocks. In short, the commodity is plentiful but geographically concentrated, the same pattern seen further down the solar chain.

What this means for India

In USGS's world production table, India appears as a ferrosilicon producer, at about 59,000 tonnes in 2024 and 2025, but no silicon-metal output is listed for it. Trade data point the same way: BigMint reported in September 2024 that India imported 45,665 tonnes of silicon metal in the first half of 2024, up 14% on a year earlier, with China supplying about 90%, mainly for aluminium alloy makers.

That gap sits directly under India's polysilicon plans. PV Tech reported that on 7 August 2026, MNRE Secretary Santosh Kumar Sarangi said a polysilicon PLI scheme being designed could cover more than 10 GW of capacity, with the incentive size not disclosed. A polysilicon plant fed by imported silicon metal would still carry an upstream dependency. For ingot and wafer makers preparing for ALMM List-III, the practical step is traceability: ask polysilicon suppliers to document the origin of their feedstock as well as its purity.

• India: ferrosilicon producer, no silicon-metal output listed by USGS
• Silicon metal imports: 45,665 t in H1 2024, ~90% from China (BigMint)
• Polysilicon PLI: being designed, >10 GW, outlay undisclosed (Aug 2026)