Optimal island configuration of floating photovoltaic systems for clean energy, water conservation, and green hydrogen production

Photovoltaic (PV) systems employing solar power to generate electricity have achieved extensive adoption worldwide and locally due to clean innovations and the electricity shortage problems. Large water reservoirs in arid and semi-arid regions worldwide suffer from significant evaporation losses, exacerbating water and energy crises. Floating photovoltaics (FPV) offer a promising dual-advantage solution by generating renewable electricity, which can also be utilized in green hydrogen production, and reducing evaporation, yet the literature lacks a model to decide the optimal spatial layout of FPV islands to maximize these benefits. This research addresses this gap by developing a generalized framework for optimizing FPV island configuration on large reservoirs. This has been carried out through a coupled physical-thermal model that integrates evaporation equations and PV cell thermodynamics with ventilation effects to develop and apply 35 scenarios. Results show that compared to a random layout, up to 18% performance improvement can be achieved when reaching the optimal island radius, which should be within the range of 140 to 180 m. Monte Carlo analysis confirms robustness; compared to baseline conditions, the current procedure saves up to 27 million m 3 of water annually and, at the same time, generates electricity reaching 18.2 GWh, produces 410 tons of green hydrogen, with a payback period of 11.2 years, a positive net present value, and an internal rate of return exceeding the capital cost. The framework is demonstrated on Mosul Dam (Iraq) as a case study but is transferable to any large reservoir worldwide.