Numerical study on the performance of solar PV/T system (PV/T-PCM) with integrated phase change material

In the solar photovoltaic-thermal (PV/T) integrated system, the photoelectric and photothermal conversion efficiencies are the core indicators for evaluating system performance. The ingenious integration of phase change materials (PCM) into the PV/T system enables the storage and efficient utilization of solar energy, overcoming drawbacks such as the intermittency of solar energy and uneven temperature distribution on the battery surface, thereby comprehensively enhancing the overall operational efficiency of the system. In this study, a three-dimensional geometric-physical and transient mathematical model of the integrated solar photovoltaic, photothermal, and energy storage system based on fractal-structured fins was constructed. The computational fluid dynamics (CFD) method was employed to solve the model, and the effects of the presence or absence of PCM, light intensity, and working fluid flow rate on system performance were analyzed. The research results indicate that the addition of PCM can significantly improve the temperature uniformity of the battery. As the solar radiation intensity increases, the liquid fraction of the phase change material also increases continuously. Temperature regulation achieved through deliberate adjustment of the cooling water inlet flow velocity proves highly effective in boosting system efficiency. Under the working condition where the inlet flow rate of cooling water is 0.1 m/s, the average electrical efficiency of the system is 1.5% higher than that at an inlet flow rate of 0.05 m/s and 5.2% higher than that at an inlet flow rate of 0.01 m/s.