<p>The primary goal of this study is to experimentally identify the most effective nanofluid coolant for enhancing the energy and exergy performance of a PVT system under real outdoor conditions of Pune, India (18.7611° N, 73.5572° E). A detailed energy and exergy analysis was carried out to evaluate thermal, electrical, overall energy, and exergy performance, and the results were compared with non-cooled PV operation. Three nanofluids of CuO, Al₂O₃, and NiO are considered as coolants to decrease PV surface temperature. Parametric evaluations were studied for the effect of ambient conditions, nanofluids, water, and non-cooled systems on heat transfer and efficiency characteristics. The indigenously designed spiral rectangular thermal absorber was proposed to recuperate heat via different coolant flows at a constant-flow rate. It was observed that nanofluid coolant was found beneficial in electrical and thermal output from the PVT system than conventional water coolant. The CuO, Al₂O₃, and NiO nanofluid coolants increased electrical power by 29.67, 26.73, and 22.19% compared to a non-cooled PV system, which resulted in 53.39, 48.09, and 39% increments in electrical efficiency. Among CuO, Al₂O₃, and NiO nanofluid coolants, CuO nanofluid was found to be superior by reporting average thermal, electrical, and overall energy efficiency of 8.81, 54.56, and 29.54%, respectively. The highest thermal exergy and overall exergy efficiency of 3.15 and 19.5% was shown by CuO nanofluid. The results clearly demonstrate that CuO nanofluid provides the optimum thermodynamic performance, yielding the highest electrical output, thermal recovery, and exergy efficiency among all tested coolants, thereby confirming its suitability for high-performance PVT applications.</p>