Numerical Study on the Performance of Solar Photovoltaic-Thermal System (PV/T-PCM) With Integrated Phase Change Material

Abstract To improve the comprehensive performance of the solar photovoltaic-thermal (PV/T) integrated system and address the issue of reduced conversion efficiency caused by increased PV temperature, this study establishes a three-dimensional transient model of a PV/T-phase change material (PCM) system with bionic fractal fins. Paraffin RT-42 (phase change temperature: 311–316 K) is selected as the PCM, and computational fluid dynamics (CFD) is employed to systematically investigate the effects of the presence or absence of PCM, fin structure, solar radiation intensity, and cooling water flowrate on system performance. The results show that the integration of PV/T and PCM significantly enhances the temperature uniformity of the PV, reducing the maximum temperature difference from 6 °C to 4 °C. Compared with the PV/T system, the thermal efficiency is improved by 24.82% and the electrical efficiency by approximately 5%. The bionic fractal fins outperform traditional straight fins in heat transfer enhancement by increasing the heat exchange area and constructing a multipath heat transfer network. When the solar radiation intensity increases from 600 W/m2 to 1000 W/m2, the system's thermal efficiency rises from 54.96% to 80.36%, while the electrical efficiency decreases from 14.38% to 13.39% due to PV temperature increase. The cooling water flowrate has a significant effect on system temperature regulation: at a flowrate of 0.1 m/s, the average PV temperature is 9.22 K lower than that at 0.01 m/s, and the electrical efficiency is improved by 5.2%. Thus, optimizing the thermal and electrical efficiency of the system can be achieved by adjusting the flowrate. This research provides a new technical path and theoretical support for improving the performance of PV/T systems.