Development of manufacturing capability for high-concentration, high-efficiency silicon solar cells

Abstract

This report presents a summary of the major results from a program to develop a manufacturable, high-efficiency silicon concentrator solar cell and a cost-effective manufacturing facility. The program was jointly funded by the Electric Power Research Institute, Sandia National Laboratories through the Concentrator Initiative, and SunPower Corporation. The key achievements of the program include the demonstration of 26%-efficient silicon concentrator solar cells with design-point (20 W/cm{sup 2}) efficiencies over 25%. High-performance front-surface passivations; that were developed to achieve this result were verified to be absolutely stable against degradation by 475 days of field exposure at twice the design concentration. SunPower demonstrated pilot production of more than 1500 of these cells. This cell technology was also applied to pilot production to supply 7000 17.7-cm{sup 2} one-sun cells (3500 yielded wafers) that demonstrated exceptional quality control. The average efficiency of 21.3% for these cells approaches the peak efficiency ever demonstrated for a single small laboratory cell within 2% (absolute). Extensive cost models were developed through this program and calibrated by the pilot-production project. The production levels achieved indicate that SunPower could produce 7-10 MW of concentrator cells per year in the current facility based upon the cell performance demonstrated during the program.