Low-cost continuous floating covers with flexible photovoltaic panels for farm irrigation reservoirs: Technical and economic analysis

In recent years, floating anti-evaporation systems have gained attention in regions with abundant water bodies that suffer substantial losses due to evaporation. This study assesses the technical and economic feasibility of an innovative floating photovoltaic (FPV) system in irrigation reservoirs in southeastern Spain. Unlike traditional rigid FPV systems, it uses flexible panels on hexagonal polyethylene floating mats, significantly reducing unit area costs and improving installation efficiency. The research addresses the water-energy nexus by integrating renewable energy generation with water conservation. In an experimental pond of 1541 m2 demonstrated a significant reduction in evaporation losses, annually averaging 82.4 %. The reduction in solar radiation incidence also limited algal and microorganism growth, improving stored water quality. The system produced over 300,000 kWh/year of clean electricity. Scheduled panel cleaning yielded an increase in energy output of 1.9–7.3 %, indicating the relevance of maintenance practices in maximising performance. Economic analysis revealed minimum Levelized Cost of Energy value of 0.042 €/kWh, and a Payback Time of 5 years, with a FPV configuration that cuts capital expenditure by roughly 40 % compared with conventional pontoon platforms, positioning the system as highly competitive under standard farming conditions. Sensitivity analysis assessed FPV coverage ratio and energy and water prices as key factors influencing profitability, indicating that energy price volatility and coverage ratio have a significant impact on economic outcomes, while water price plays a comparatively minor role. Overall, the system presents a viable and scalable solution for farmers, offering a dual benefit of clean energy generation and substantial water savings.