An assessment study of evaporation rate models on a water basin with floating photovoltaic plants

Under the general topic of the impact of floating photovoltaics (FPVs) systems on water basins, the present study aims to model and analyze the effect of FPVs on the evaporation rate of water surfaces. The estimation of the evaporation of the water surface of a basin is usually calculated using mathematical evaporation models that require knowledge of some parameters (ie, solar radiation, humidity, air temperature, water temperature, and wind velocity). Thus, in the first section of this study, some evaporative models (EVM) for free water basin have been examined to evaluate which are the environmental variables used. On the basis of this analysis, new numerical models for the calculation of the daily evaporation rate have been developed using the design of experiments (DoE) method (three models) and the linear regression method (two models). The results of the developed models have been compared with the experimental measurements carried out by an evaporimeter; such comparison has highlighted the robustness of the proposed numerical models. Moreover, for estimating the evaporation rate in water basins partially covered by FPVs, further three numerical methods are proposed. Finally, the evaporation rates, arising by the installation of different typology of FPVs on water basins, have been evaluated as function of the energy balance on the water surface. It is possible to highlight that the amount of evaporated water depends not only on the percentage of surface covered but also on the characteristics of floating systems. Covering only 30% of the surface of a basin, it is possible to obtain up to 49% reduction in evaporation.