Red Herring has an article telling of SolarWorld forming a joint venture to "turn dirty metallurgical-grade silicon into high-purity solar-grade silicon." They also report that: "According to SolarWorld, the joint venture will develop and build a manufacturing plant to produce, initially, 1,000 tons (per year?) of solar-grade silicon from metallurgical-grade silicon."
They also report on other recent entries into the solar silicon market and quote Jesse Pichel, a vice president and senior research analyst of technology at Piper Jaffray as saying“There’s no reason to go to metallurgical silicon,”
The article goes on to question this statement.
From all that I have read, the silicon shortage will not go away in a couple of years as some say, but will continue as long as sales of solar modules continue to grow at 25% to 35% a year. This rate of growth is necessary for an extended period if silicon PV solar is to continue to be the major source of PV modules and PV solar becomes the alternative energy source of choice. The only fly in the ointment is if CIGS and/or CIS technology develops as proponents say and it becomes the low cost source. I have no knowledge of the merits of metallugical silicon.