Improved High-Efficiency Silicon Concentrator Cells for Medium Concentration Applications

摘要

This report describes efforts toward design simplification of Si concentrator cells capable of efficiencies in the 25-30% range. A discussion is given on the principal issues involved in the design and fabrication of both backside-contact cells and cells with frontside grids. Several proposed designs are detailed. Results include 23% two-sided 1.5625 sq cm cells operating at 14 W/sq cm of incident power. This simple design requires only one mask alignment and should approach 25% with further development. With an additional alignment, cells that are 27% efficient are feasible. Neither of these designs will require prismatic cover glasses to achieve this performance. In addition, a new backside contact cell design is described that requires only one mask and no alignments. Cells of this type were demonstrated to be 15.4% efficient at 4 W/sq cm, without AR coatings or texturization. Fundamental studies of the limiting parameters indicate that the design will exceed 25% in efficiency when fully developed. Finally, a new light-trapping scheme is proposed which could have the effect of increasing the attainable efficiencies of silicon concentrator cells to 32-33%. This same scheme might also be utilized in ways which would allow very simple low-cost cell designs to achieve results comparable to the best cells demonstrated to date. Assorted other practically-oriented results on metalization development, cell mounting, and qualification tests are also presented. 26 refs., 31 figs. (ERA citation 14:024278)