Experimental performance evaluation of a dual-purpose photovoltaic-thermal system with phase change material for passive heating and cooling

Photovoltaic thermal technology (PVT) is gaining increasing attention due to its improved performance and reliability made possible by continuous technological advances. Despite these significant advances, the potential of PVT modules to simultaneously heat, cool and generate electricity passively remains unexplored. In this study, we developed a dual-purpose PVT collector that can passively heat and cool to improve both electrical efficiency and thermal energy management, without relying on external power supply. . . By using CaCl 2 -6H 2 O as an inorganic phase change material (PCM), the latent heat of fusion of the PCM passively cools the circulating air and thus improves the electrical efficiency of the PVT module. The cooling and heating performance of the system was analyzed using CFD (Computational Fluid Dynamics) simulations conducted with ANSYS FLUENT. Subsequently, the experimental performance of the system was evaluated in two periods — September and December — in a greenhouse under the climate conditions of Tehran, Iran. The results showed an 11.28% increase in cooling efficiency and a 4.23% improvement in power generation efficiency for the PVT-PCM collector, while an 18.86% improvement in heating efficiency was achieved over a longer period. In September, the observed cooling efficiency was12.92%,1.64% below the value predicted by the simulations. While the simulations calculated a heating efficiency of 20.31%, the tests conducted in December showed an actual efficiency of 18.86%. During the night-time heating, the PCM solidified in 130 minutes, while the simulations predicted a solidification time of 120 minutes. The predicted and actual values showed a strong correlation, with an R-squared value of 0.9923. These results underline the effectiveness of the passive cooling and heating system in greenhouses and demonstrate its ability to improve electrical efficiency. • A photovoltaic-thermal collector with PCM is developed for passive heating and cooling. • A sustainable solution is offered for building applications without a need for an external power. • Improvements of 4.23% in electricity, 11.48% in cooling, and 18.86% in heating are achieved. • Agreement between experimental and simulation results, with an R 2 value of 0.9923 is achieved. • Passive cooling reduces PV temperature by up to 7°C and improves electrical efficiency.