Developments in module ready SI backside-contact solar cells

Moderate quantities of high-efficiency Si backside-contact solar cells were fabricated. Compromises were made at the design level in order to investigate the possibilities for obtaining a high fabrication yield. The cells were tested in a module-ready state, soldered down to copper cell mounts. The efficiencies for the best cells peak at 26% for a range of 5-12 W/cm² (50-120 suns). For a design point of 36 W/cm², a majority of the 283 cells from two successive runs have efficiencies in a tight distribution around 23%. The performance difference between these cells and the best laboratory cells demonstrated to date (26% versus 28.3%) is primarily due to the sunward-side dopant diffusion, not present in the previous cells but incorporated in the current designs in order to make them stable to degradation in ultraviolet light. Accordingly, improved performance is expected to come primarily from improvements in stable front-surface passivations