The temperature of floating photovoltaics: Case studies, models and recent findings

In floating photovoltaics (FPV), modules are installed on water to alleviate the land requirement of this energy source. In addition, FPV installations are expected to work at lower operating temperatures compared to land based photovoltaic (LPV) systems, thanks to the cooling effect of water. If confirmed, these lower temperatures would (i) increase the energy yield and (ii) reduce degradation and performance losses, boosting the cost-competitiveness of FPV. However, some recent works have reported cases of FPV systems working at higher temperatures than co-located LPV systems. The present review gathers the literature on the thermal behaviour of FPV, outlining the models and discussing the currently available experimental results. It is found that FPVs of different configurations can experience different thermal behaviours, not always necessarily better than LPV. In particular, air- and water-cooled FPV systems should be always distinguished, considering their diverse cooling mechanisms. Initial comparative analyses make it possible to identify designs and conditions that can favour the heat transfer in FPV compared to LPV. The role of additional factors on the FPV temperature, such as the PV material or the more frequent biofouling, is also discussed. Last, estimations of the economic impact of the thermal behaviour on the FPV costs and competitiveness are presented.