Large-area 21% efficient Si solar cells

Large-area 21% solar cells have been developed for applications requiring very high efficiency and low weight. Completed 35 cm² cells with soldered copper tabs have efficiencies of over 20% with some cells exceeding 21% as measured by Sandia National Laboratories. They were fabricated in an industrial environment using a process optimized for the fabrication of cost-effective concentrator solar cells. The cells are based upon a design demonstrated at Stanford University. Significant improvements in the commercial product include the optimization of the cell layout to allow large solderable busbars, an antireflection coating, and an entirely new fabrication process based upon POCl₃ and BBr₃ doping sources