Boosting floating photovoltaics via cooling methods and reservoir characteristics: Crafting optimal symbiosis with off-river pumped hydro storage

The cooperation of off-river pumped hydro storage (OFPHS) and floating photovoltaics (FPV) as a new combined power generation mode effectively addresses the issue of traditional pumped hydro storage (PHS) site selection relying on rivers, resulting in limited in FPV coverage. However, the operation of FPV is constrained by the reservoir's shape and minimum water level, which reduces the flexibility of OFPHS. Therefore, this paper constructs an optimization model for hydro-wind-photovoltaic energy system of OFPHS and FPV cooperation (OFPHS + FPV). Subsequently, analyze the influence mechanism of different cooling methods of FPV and reservoir characteristics on the energy system and formulate the optimal operating strategy. The results show that the FPV water cooling system is significantly superior to air cooling system in terms of improving power generation efficiency and reducing evaporation. Moreover, in terms of technology and economy, the OFPHS + FPV performs best when the reservoir's minimum water level is 6.34m and useable capacity is 70 %, with a loss of load rate of 3.05 % and an operating cost of 4.57 × 10⁷$. In terms of environment, the OFPHS + FPV performs best when the reservoir's minimum water level is 8.95m and useable capacity is 56.5 %, saving 6.75 km² of land and reducing evaporation by 4.80 GL.