Growth in world-wide demand for silicon (Si) photovoltaics (PV) and a short-fall in the traditional supplies of Si into the PV industry call for renewed interest in determining the quantities of Si required per megawatt, the specifications for solar grade Si feedstock, and the technologies for producing such material. An ample, dedicated and consistent solar Si supply independent of the Si electronics industry is recommended. Low cost (less than $20 per kg) solar Si feedstock is part of the technology portfolio for achieving PV products in the $1 per watt range.