Parasitic Heating of Perovskite- and Silicon-Based Photovoltaics

摘要

The origins of parasitic heating for photovoltaic (PV) technologies based onsilicon, perovskites, and their combination in monolithic tandems areinvestigated. To quantify heating losses, the cooling score (CS) as a newsimple metric, representing the percentage of incident solar irradiance notcontributing to module heating is introduced. This is a function of both theoptical structure and power conversion efficiency (PCE) of the PV modulesand allows a fair comparison between different technologies under identicalperformance-evaluation scenarios. Silicon single-junction devices have thelowest CS due to their low bandgap (causing significant carrier thermalizationlosses) and their use of light-trapping structures to increase their PCE whichalso undesirably increases parasitic absorption of sub-bandgap photons.Conversely, perovskite single-junction devices show the highest CS in allstudied performance-evaluation scenarios thanks to their wider bandgap andhigh absorption coefficient, enabling absorption of all solar photons that maycontribute to the photocurrent without requiring light-trapping structures.While perovskite/silicon tandems minimize thermalization losses, they alsousually employ light-trapping structures in their bottom cell to increase theirPCE, which lowers their CS. Through simulation and outdoor experiments, itis demonstrated that an efficient module-cooling environment maysignificantly suppress the detrimental effects associated with a low CS.