Solar grade silicon: Technology status and industrial trends

Crystalline silicon remains (all variants included) the dominant technology to manufacture solar cells. Currently (2012-2013) more than 90% of all solar cells produced are based on this vast group of technologies. The availability, the cost and the quality to the silicon feedstock is therefore a strategic issue of paramount importance for the entire photovoltaic sector. The silicon demand/supply balance has evolved from a situation of shortage with rocketing sales prices, in the years 2005-2008, to currently (2012-2013) an oversupply situation with record low price level for virgin polysilicon. Between these two extreme periods, production capacity has been multiplied by a factor of nearly 10. A better understanding of the prevailing dynamics in the polysilicon/silicon industry is needed in order for all players in the solar cell industry to make proper planning. In light of the past developments as well as the constraints imposed by a sound competition, the present article reviews the market trends for solar grade silicon including capacity, supply, demand and price. Furthermore, the article reviews the competing commercial technologies i.e. Siemens polysilicon, fluidized bed reactor/FBR polysilicon and upgraded metallurgical/UMG silicon and compares them in terms of maturity, improvement potential, product morphology, purity, applications and cost (actual vs. potential).