Red Herring reports that SRI International has licensed technology to produce lower cost solar-grade silicon to three Asian companies and that pilot plants could be up and running in 18 months.
SRI’s technology promises to make solar-grade silicon for $14 per kilogram, less than half the price of competing technologies, Mr. Dubois says. SRI claims its process produces silicon with almost no impurities (0.02 parts per million) at one-tenth the energy and one-fifth the capital costs of the conventional Siemens process used by most of the big polysilicon manufacturers. So far, SRI’s technology has only been used in the lab. But analysts say that, with contract prices rising up to $85 per kilogram and non-contract prices skyrocketing to $200 per kilogram, companies are willing to try new technologies.
A 1986 patent by A. Sanjurjo, assigned to SRI, is described as follows:
Apparatus is described for producing low cost, high purity solar grade silicon ingots in single crystal or quasi single crystal ingot form in a substantially continuous operation in a two stage reactor starting with sodium fluosilicate and a metal more electropositive than silicon (preferably sodium) in separate compartments having easy vapor transport there between and thermally decomposing the sodium fluosilicate to cause formation of substantially pure silicon and a metal fluoride which may be continuously separated in the melt and silicon may be directly and continuously cast from the melt.