Upgrading Metallurgical Grade Silicon to Solar Grade Silicon

Abstract

The photovoltaics (PV) is a method of direct conversion of solar energy to electricity using semiconductor solar cells. In terms of globally installed capacity, PV remains third the most important renewable energy source after hydro and wind powers. 31.1 GW of PV systems were installed around the world in 2012 and up from 30.4 GW in 2011.There is a rapid growth of PV cell production and it is expected to increase further. However PV technology have to cost effective in comparison to hydro or wind powers and other sources of renewable energy. It has to reach the “grid parity” i.e. less or equal price for generated electricity power. More than 85% of solar cells (SC) are made from solar grade silicon (SoGSi). SoGSi is produced by purification of metallurgy grade silicon (MGSi) which is produced by carbon recovering silicon from quartz. Also Quartz is an initial and essential material for obtaining SoGSi and SC. Rich resource of quartz Sarykol located at southern part of Kazakhstan where the main factory for MG Si production «Каzsilicon» is situated. Upgrading of MGSi up to SoGSi consists is a number of technological steps and SoGSi is basis for PV industry. Therefore the cost of SoGSi determines the competitiveness of PV technology compared to other energy sources. There are several chemical and metallurgical technologies for SoGSi production. This paper briefly describes these technologies and shows main advantages of metallurgical technologies based on slag refining (oxygenation). Considered technologies are the basis for industrial production of SoGSi, solar cells with an efficiency of 15.8-17.1% and solar panels. The 1st power plant made from solar panels in Kazakhstan was launched in December 25, 2012 by «AstanaSolar» with a total capacity of 250 kW.