|Polysilicon is right at the beginning of the Solar PV chain. It is the feedstock material for the production of solar cells. Polysilicon, as the name goes, consists of multiple small silicon crystals. It is technically industry-grade silicon. Such industry-grade can be reached only by extensive purification of widely available silicon.
Silica is the starting material for the manufacture of polysilicon. Quartzite contains the highest concentration of silica, and thus quartzite is used as the starting material for silicon based solar PV cells.
The path from quartzite to hyper-pure polysilicon is a detailedtask. It involves the Siemens Process in which quartzite is distilled and decomposed into highly pure silicon, with purity levels of 6N(99.9999%).By the way, the polysilicon used for the PV industry isn’t expected to be as pure as that required by the semi-conductor industry where they are expected to have purity levels in the range of 99.9999999%(9N).
Polysilicon is converted into ingots which are cut into thin wafers. Solar cells are made from these wafers and assembled to form solar modules and further on, solar panels.