Evaluation of potential benefits from photovoltaic development on the existing hydropower reservoirs in the Upper Yellow River

To achieve the goal of carbon peak and carbon neutrality, the installed capacity of photovoltaic (PV) power generation in China will continue to grow rapidly, and the land use is a key issue facing its development. Floating PV, as an important PV development mode, especially in arid and semi-arid regions, shows significant benefits over land-based PV in terms of land conservation, water evaporation reduction, PV performance improvement and mitigation of aquatic weed growth. Also, if floating PV could be integrated with existing hydropower, it would contribute to the transmission and large-scale consumption of PV power generation. However, these benefits are often presented in a qualitative manner and systematic quantitative analysis has not yet been available. Based on hydropower plant information, meteorological data, PV system performance model and water evaporation model for water bodies covered by PV system, this paper evaluates the potential power generation, land conservation and water evaporation reduction benefits from floating PV in the "existing hydropower + floating PV" power generation system, and the feasibility of implementation of the system, taking the Upper Yellow River from Eling Lake estuary to Qingtong Gorge as the study area. The results show that if the floating PV system covers 10% of the water area at the existing hydropower reservoirs, the annual economic benefits in terms of power generation, land saving and water evaporation saving are 5.38 billion yuan, 0.078 billion yuan and 0.052 billion yuan, respectively, with a cumulative annual economic benefit of 5.51 billion yuan. The total investment and potential net income at the end of the lifecycle are 93.06 billion yuan and 41.47 billion yuan, respectively, with an average return on investment of 1.78%, which makes the construction economically feasible. The results of this paper confirm the comprehensive benefits of the "hydropower+floating PV" power generation system, which can help China to adjust and optimize the relevant policies as well as contribute to the sustainable development of PV projects.