Research on performance improvement of photovoltaic/thermal system based on series-parallel composite flow channel

To resolve the inherent trade-off between electrical and thermal efficiencies—a core challenge in traditional photovoltaic/thermal (PV/T) systems—three collectors with distinct flow channel designs (series, parallel, and series-parallel hybrid) are proposed to improve the comprehensive utilization efficiency of solar energy. Outdoor comparative experiments were performed on a conventional PV system and the three proposed PV/T systems, focusing on key performance metrics and the regulatory effect of mass flow rate. The results indicate that at a mass flow rate of 1 L/min, the hybrid system achieves an electrical efficiency of 12.1% (a 12% increase compared to the series-type configuration) and a thermal efficiency of 36.71% (a 28% improvement relative to the parallel-type configuration), with an average inlet-outlet temperature difference of 4.32 °C. The parallel-type system exhibits the optimal electrical performance, with an electrical efficiency of 13.31% and a 17 °C temperature reduction compared to the conventional PV system. In contrast, the series-type system demonstrates superior thermal performance, achieving a thermal efficiency of 44.78% and a primary energy saving efficiency of 74.77%. For all three systems, the electrical efficiency, thermal efficiency, and primary energy saving efficiency increase with the rise in mass flow rate, while the inlet-outlet temperature difference shows an inverse relationship with flow rate. Through its synergistic configuration, the hybrid flow channel realizes the synchronous enhancement of electrical and thermal performances and improves the grade of the extracted thermal energy, providing crucial technical support for the application of renewable energy in building integration.