The expansion will provide polysilicon for Hemlock's solar and electronics operations in Michigan and Tennessee.

Hemlock Semiconductor group, which includes two joint ventures with Dow Corning, said an initial $1.2 billion investment will be used to launch new operations in Clarksville, Tenn. Up to $1 billion will be used to expand current operations in Hemlock, Mich.

The combined expansion is expected to add another 34,000 metric tons of polysilicon capacity, Hemlock said.

Most of the polysilicon produced by the new facilities will be used by solar cell manufacturers. Both Hemlock plants also will be able to manufacture ultra-pure silicon for the electronics industry as well as solar-grade material, the company said.