Thermodynamic Modeling and Multi-Generation Performance of an Integrated Solar PV/T and Active Water Purification System

The simultaneous generation of electrical power and potable water represents a critical engineering objective for off-grid coastal and deltaic communities. In standard flat-plate photovoltaic (PV) modules, over 80% of incoming solar irradiance is converted into waste heat, elevating cell temperatures and substantially reducing electrical conversion efficiency. In this study, we present a comprehensive first- and second-law thermodynamic design of a hybrid Photovoltaic-Thermal (PV/T) co-generation system directly coupled to an active solar desalination and water purification basin. A continuous forced-circulation cooling loop extracts thermal energy from the rear of monocrystalline silicon cells, maintaining operating temperatures below 45°C to enhance electrical efficiency, while feeding preheated saline/brackish water (55°C–70°C) into an insulated distillation chamber. We formulate the coupled differential energy balance equations for the glazing, PV layer, absorber plate, heat-transfer fluid, basin water, and condensing glass cover. A rigorous exergy destruction analysis based on the Petela solar radiation model quantifies the thermodynamic irreversibilities of each component. Under peak tropical irradiance (GT = 1000 W/m², ambient temperature Ta = 30°C), the integrated system achieves a stabilized electrical efficiency of 14.8% (an 11.2% relative gain over uncooled PV), a thermal collection efficiency of 52.4%, and a steady freshwater distillate yield of 4.85 kg/m²·day, with an overall system exergy efficiency of 13.9%.