Photovoltaic solar cells performance at elevated temperatures

It is well known that efficiency of photovoltaic solar cells decreases with an increase of temperature, and cooling is necessary at high illumination conditions such as concentrated sunlight, or cosmic or tropical conditions. The purpose of present study was to investigate the opposite option: to make a cell work at relatively high temperature (around 100-200 °C) and use the excessive heat in a hybrid system of some kind to increase the total efficiency of solar energy utilization. We studied the temperature dependence of the solar cell parameters both theoretically and experimentally, for the basic cells with p-n junction and the Schottky barrier, taking account of the different carrier transport mechanisms and recombination parameters of the cell material. The possibility of usage of the concentrated sunlight was also taken into account. The experiments conducted in the temperature interval of 25-170 °C and the calculated data show a real possibility of construction of a two-stage solar-to-electric energy converter with high-temperature second stage, having the overall conversion efficiency of 30-40%.