Production viability of gallium doped mono-crystalline solar cells

Results of efforts at Shell Solar to implement the use of gallium dopant as a commercial solar cell production process are presented. Both small area cell results and production related activities and results are discussed. Many researchers have demonstrated that gallium effectively eliminates light induced degradation (LID) of the bulk lifetime, but less effort has been dedicated to implement gallium dopant into a commercial production process. Shell Solar has worked in this direction and expanded past research activities to demonstrate that the full range of resistivity values produced from a gallium-doped crystal can be used to successfully fabricate high efficiency cells. In addition, Shell has produced significant numbers of gallium-doped cells in their production facility and characterized process results from crystal growth to module build. This paper discusses additional subjects essential to production viability, such as gallium metal availability, silicon feedstock availability and management specific to a gallium process and overall cost effectiveness.