Multicrystaline solar silicon production - ingot casting

Multicrystalline silicon is produced in a variety of ways. However, the cost wise most popular commercial method is the ingot casting process. When solar silicon is produced appliying the cast method, pieces of silicon are molten in large ceramic crucibles.

The silicon feedstock is melted at temperatures ranging above 1400°C by means of an induction heating and directly cast into a mold and allowed to solidify into an ingot.

During the melting process, a small quantity of boron is mixed into the material to get it's positive characteristics and make the silicon p-type.

The multicristallin silicon ingots measure approximately 50 cm in lenght and 30 cm in height and width. The cast ingot is divided into smaller blocks for subsequent wafer production.

Merely 70% of the produced polycrystal silicon is manufactured into wafers. The rest gets lost in the sawing and cutting process.

According to a study of Karlsruhe University a total of 660kWh are necessary to produce 1kg of solar grade silicon (SGS).

More information can be obtained reading » SILICON CASTING PROCESS FOR PHOTOVOLTAIC