Climatic impact on the efficiency of a copper indium diselenide module

The experiments investigate the influence of climatic parameters on the efficiency of a commercially available copper indium diselenide (CIS) module. The results allowed to develop a five-parameter model describing the efficiency as a function of irradiance, cell temperature and relative air mass. The model is indispensable to determine accurately the yearly output of CIS modules at different sites with given meteorology. Two quantities were calculated from the model as by-products, namely the cell efficiency at standard test conditions (STC) and the temperature coefficient of the cell efficiency at STC, being 11.6% and -0.050 abs.%//spl deg/C, respectively. The efficiency decreases linearly with cell temperature. However, the decrease is less pronounced than with crystalline silicon modules. The efficiency of the module is practically independent on air mass. This is in contrast to amorphous silicon modules as well as micro-morphous tandem and amorphous triple- junction silicon modules, which show a decrease in efficiency in the late afternoon due to the increasing air mass and a simultaneous red shift of the solar spectrum.