In this study, a performance evaluation of a photovoltaic thermal (PVT) system using nanofluids was carried out through an efficiency comparison study using water, CuO-water, and Al₂O₃-water nanofluids as the heat medium of the PVT system. In addition, a model for computational fluid dynamics (CFD) analysis was established, and the validity of the model was verified by comparing it with the experimental results of the PVT system. Through this, it was confirmed that the outlet temperature of the PVT system using nanofluids can be predicted by applying various conditions. Based on the results, the use of nanofluid as heating medium for the PVT system is proposed to improve the efficiency sufficiently compared to the conventional heating media.

Fossil fuels are being depleted, resulting in increasing environmental pollution due to greenhouse gases and, consequently, emerging detrimental environmental problems. Therefore, renewable energy is becoming more important; hence, significant research is in progress to increase efficient uses of solar energy. In this paper, the thermal performance of a conical concentrating system with different heat transfer fluids at varied flow rates was studied. The conical-shaped concentrator reflects the incoming solar radiation onto the absorber surface, which is located at the focal axis, where the collected heat is transported through heating mediums or heat transfer fluids. Distilled water and nanofluids (Al₂O₃, CuO) were used in this study as the heat transfer fluids and were circulated through the absorber and the heat storage tank in a closed loop by a pump to absorb the solar radiation. The efficiency of the conical concentrating system was measured during solar noon hours under a clear sky. The collector efficiency was analyzed at different flow rates of 2, 4, and 6 L/min. The thermal efficiency, calculated using different heat transfer fluids, were 72.5% for Al₂O₃, 65% for CuO, and 62.8% for distilled water. Comparing the thermal efficiency at different flow rates, Al₂O₃ at 6 L/min, CuO at 6 L/min, and distilled water at 4 L/min showed high efficiencies; these results indicate that the Al₂O₃ nanofluid is the better choice for use as a heating medium for practical applications.