Ingots

Ingots are solid blocks of material produced by cooling and solidifying a molten substance. They serve as an intermediate form that can be processed into products with specific shapes and properties. Although the term commonly refers to metals, it also applies to crystalline silicon used in solar manufacturing.

In the solar industry, high-purity silicon, known as polysilicon, is melted and solidified under controlled conditions to form an ingot. Its crystal structure determines whether the resulting material is monocrystalline or multicrystalline:

Monocrystalline ingots: Usually grown by slowly pulling a rotating seed crystal from molten silicon, a technique called the Czochralski process. This produces a single, continuous crystal, typically with a cylindrical shape.
Multicrystalline ingots: Produced by solidifying molten silicon in a mould, creating a block containing multiple crystal grains.

The ingots are then shaped and sliced into thin wafers, typically using diamond-wire saws. Those wafers undergo further processing to become solar cells, which are connected and assembled into photovoltaic modules.

Ingot purity, crystal quality and structural consistency influence manufacturing yield and the performance of the finished cells. Defects or impurities can reduce the material’s ability to support efficient electricity generation.

In the solar supply chain, ingots sit between polysilicon production and wafer manufacturing. Their capacity is often expressed in gigawatts to indicate the equivalent solar-cell output the material could support, rather than electricity generated by the ingots themselves.