Evaluation of Reference Evapotranspiration Estimation Methods for the Assessment of Hydrological Impacts of Photovoltaic Power Plants in Mediterranean Climates

Large-scale photovoltaic (PV) power plants may affect the hydrological cycle in all its components. Among various components, evapotranspiration is one of most important. As a preliminary step for assessing impacts PV on evapotranspiration, this study, we performed an evaluation study methods estimating reference (ETo). FAO and ASCE recommend Penman–Monteith (PM) method estimation ETo when data involved variables are available. However, often not case, different empirical to estimate ETo, requiring mainly temperature data, need be used. This aimed at performance temperature- radiation-based against standardized PM experimental plant Piazza Armerina, Sicily, Italy, where meteorological station set sensors soil moisture were installed. The obtained from Lab July 2019 end January 2022. By taking estimations as benchmark, assessed methods. In particular, following considered: Hargreaves Samani (HS), Baier Robertson (BR), Priestley Taylor (PT), Makkink (MKK), Turc (TUR), Thornthwaite (THN), Blaney Criddle (BG), Ritchie (RT), Jensen Haise (JH) methods, using several metrics. result showed that PT best method, with Nash–Sutcliffe efficiency (NSE) 0.91. second order HS, which, however, performs significantly worse than (NSE = 0.51); nevertheless, among only data. BG, TUR, THN underestimate while MKK, RT, JH overestimation method. HS thus reliable studied site.