INVESTIGATION OF HIGH-CONCENTRATION PHOTOVOLTAIC CELL PACKAGES AFTER 3 YEARS FIELD SERVICE

As part of a controlled, step-wise development program, silicon cells from an early production run were assembled into packages and installe d in a prototype electrical module. After three years field service, t he module was disassembled and the cell packages were examined in deta il. Although all 48 cell packages were still functional, significant c racking was discovered in the solder layers between ceramic stand-offs and copper heat-spreaders. A simplified analysis of thermal fatigue a s a cyclic creep process predicts useful lives of about twelve years f or cell packages of this configuration and solder joint thickness.