Jitendra Satpute, Jana Petrů, Vinod B. Hiwase, Pravin Thorat, Rupesh Sundge, Shylesha V. Channapattana, Muhammad Nasir Bashir, Joon Sang Lee, Sunita Yadav, Srinidhi Campli
The present study investigates the performance enhancement of photovoltaic–thermal (PVT) systems using a comparison of conventional water coolant and Al 2 O 3 –water nanofluid coolant. Outdoor experiments were conducted in Pune, Maharashtra, India, by varying Al 2 O 3 nanoparticle concentrations in a spiral copper thermal absorber integrated with a polycrystalline PV module. The objective was to evaluate how coolant type and nanoparticle loading influence overall PVT system efficiency with practical feasibility. The study uniquely combines thermal, electrical, hydraulic considerations to identify the realistic applicability of Al 2 O 3 nanofluid cooling in PVT systems with spiral thermal absorber. This holistic approach provides practical insights for optimizing PVT performance in domestic and industrial applications under Indian climate conditions—representing a significant advancement over existing studies. The higher thermal conductivity of the Al 2 O 3 nanofluid facilitated more effective heat extraction from the PV surface, resulting in reduced operating temperature, improved electrical output, and enhanced thermal energy recovery. Al 2 O 3 water-nanofluids proved particularly effective, enhancing thermal conductivity and facilitating heat recovery of 5–12 °C. Improvements were observed in thermal efficiency (57.51%), electrical efficiency (9.8%), overall efficiency (67.31%), and energy-saving potential (30.66%). For the water-cooled PVT system, a Reynolds number of 1717.6 was recorded, which decreased by 11.67% to 1517 at the highest nanofluid concentration. The friction factor increased from 0.0906 (water cooling) to 0.0966 with 5% Al 2 O 3 nanofluid, while the pressure drop rose from 521.0 to 829.6 Pa. Although performance improves with increasing nanoparticle concentration, the accompanying rise in viscosity, friction losses, and preparation cost leads to higher pressure drop and pumping requirements.