PHOTOVOLTAIC SOLAR CELLS PERFORMANCE AT ELEVATED TEMPARATURES

摘要

It is generally accepted that efficiency of photovoltaic solar cells decreases with an increase of temperature, and the cooling is necessary at the conditions of high illumination like concentrated sunlight, cosmic or tropical conditions. The purpose of present study was to investigate the opposite option: to make a cell work at relatively high temperature, 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 cells made of the different semiconductors and having the different structure, 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 made at the temperature interval 25 – 100ºC on the Si monocrystalline cells with p-n junction and Schottky barrier, tandem amorphous Si cell and the CIS (CuInSe2_) thin film cell. We found that, in accordance with theoretical predictions, the Si crystalline cells with Schottky barriers, a-Si and the CIS ones at one sun illumination conserve at 100°C not less than 70 % of their initial efficiency, whereas the Si p-n junction cell have at this temperature only around 30 % of the efficiency at room temperature. The results obtained show a real possibility of construction a two-stage solar-to-electric energy converter with high-temperature second stage, having the overall conversion efficiency about 40 %.