Water–energy nexus analysis of floating PV systems: impact of footprint design on evaporation control and energy yield

The rapid deployment of floating photovoltaics (PV) offers a dual-modality solution for energy and water security by preserving land, enhancing energy yield through cooling, and mitigating evaporation. This study utilizes a commercially calibrated simulation framework to evaluate the performance of three PV configurations—rooftop, small-footprint (SF) FPV, and large-footprint (LF) FPV—under the specific climatic conditions of Türkiye. Comparative results indicate that the SF FPV configuration achieves the highest annual grid-delivered energy (Egrid = 37,320.0 kWh) and the most favorable greenhouse gas payback time (GPBT ≈ 0.80 years), closely followed by LF FPV (≈ 0.81 years), while the rooftop TOPCon system yields a GPBT of ≈ 1.15 years. Beyond energy metrics, volumetric water savings were quantified, revealing that open-water evaporation from the reservoir (513,268 m³/year) can be reduced by 295,919 m³/year under 80% LF FPV coverage. This saving represents 14.47% of the total storage capacity, equivalent to the annual irrigation demand of approximately 148 hectares of cropland. Seasonal analysis further highlights that evaporation reductions are most significant during summer months, with daily evaporation in July decreasing from 5.422 to 2.612 mm/day under maximum coverage. Ultimately, while SF FPV optimizes energy generation and carbon recovery, LF FPV maximizes water preservation, demonstrating that integrated water-energy management strategies can be tailored to the specific resource priorities of arid and semi-arid regions.