Hybrid PVT-PVSFs powered desalination system with phase change material thermal energy storage: Dynamic simulation in an actual weather condition for sustainable off-grid freshwater production

The growing demand for freshwater in rural and off-grid communities highlights the need for sustainable desalination systems that operate independently of fossil fuels and unstable grid electricity. This study investigates a hybrid solar-powered desalination unit that integrates a photovoltaic–thermal collector with perforated V-shaped fins, a water-based phase change material (PCM) thermal storage tank, and a two-stage reverse osmosis (RO) system. A coupled simulation framework combining computational fluid dynamics, dynamic thermal modeling, and RO process software was developed to evaluate thermal, electrical, and water production performance under realistic weather conditions in Tangshan, China. Results show that the hybrid collector reduced average photovoltaic cell temperature by 14.8 %, lowering the peak temperature by 12.7 °C and enhancing electrical efficiency by 7 %. The PCM tank with 50 kg of storage material increased stored energy by 27.7 % and stabilized outlet temperature. Thermal preheating reduced RO feed pressure by 0.7–1.0 % and decreased the specific energy consumption from 5.086 to 4.831 kWh/m³, a 5.0 % saving. Unlike previous solar RO systems that focus primarily on either PV cooling or thermal storage in isolation, the present work uniquely combines PVT-PVSFs active thermal management, PCM-based energy buffering, and two-stage membrane desalination in a single integrated platform evaluated through multi-physics simulation using ANSYS Fluent, Python, and Toray RO software. The results demonstrate a viable and economically competitive approach for decentralized, emission-free desalination, achieving a water cost of approximately 3 USD/m³ and a payback period of 5.3–7.4 years in solar-rich regions.