Multiscale prediction of localized hot-spot phenomena in solar cells

Hot-spot phenomena in photovoltaic (PV) devices may suppress the performance and cause irresistible damage. Traditional study focuses on hot spots caused by shade or faults of PV modules, discussing the systematic failure. Different from that, this study focuses on hot-spot phenomena due to nonuniform heat generation within a unit cell of the module, which is resulted from surface microstructures, locally enhanced absorption and uneven concentration of light. In this paper, the volume heat generation in a cell is derived by modeling interactions between photons, excited free electrons and lattice phonons. And significant unevenness of heat generation is found. Based on the 3D heat distribution, transient simulations of cell temperature are conducted. Although hot-spot phenomena are negligible in nonconcentrated PV cells, in a 400 x (1000 x ) high concentrator photovoltaic(HCPV) cell, remarkable hot spot is found with maximum temperature difference of 68K(169K) and the local hottest spot reaches 372K(491K). More seriously, in cloudy or windy days, cells may be shaded constantly, leading to sharp and constant temperature variation at the hot spot area in tens of microseconds. All these results creatively reveal that localized hot-spot phenomena within a cell may significantly suppress the cell performance and shorten the lifespan. (C) 2019 Elsevier Ltd. All rights reserved.