New Methods for the Production of Solar Grade Silicon

Abstract

During the last few years, there has been a strong economic growth around 30% in photovoltaic (PV) industry which has resulted in a shortage of polysilicon feedstock. On one hand, the supply of waste wafers from IC industry can not meet the need of PV industry. On the other hand, silicon feedstock made by siemens method has a much higher price and purity than the PV industry prefers. Therefore, the PV industry requires a new kind of silicon feedstock—solar grade silicon(SOG). It is well known that the price of solar cell module is still high for mass application and the cost of silicon wafer is about 40% of the cost of a module. Lots of new methods for the production of Solar Grade Silicon appeared, as it is important to reduce the cost of silicon feedstock for further development of PV industry. In this article, some of the recent development and approaches that might benefit the PV industry are reviewed and outlined. These new methods can be divided into two kinds according to their purification process: gas rectification methods and molten silicon purification methods. None of the methods has absolute advantage to the others. Each of the methods is still far from satisfaction to mass production and hence, further research is still necessary in this field.