Modeling and simulation of a novel dual-channel photovoltaic thermal system

Solar photovoltaic thermal (PV/T) systems have gained increasing attention due to their ability to simultaneously generate electricity and thermal energy. PV/T systems typically employ air and water as working fluids to reduce cell temperature and recover waste heat. Active cooling for the PV cell is beneficial for boosting electrical output. In addition, the captured thermal energy can be directly utilized for domestic hot water supply and industrial heating applications. However, the single-channel PV/Tsystem faces challenges in adapting to high-temperature environments and peak thermal demand periods. Furthermore, the single-channel PV/T system exhibits limited control flexibility due to single-mode operation and slow response characteristics. The dual-channel PV/T system requires additional components, but it improves thermal energy recovery capabilities. It can reduce primary fuel consumption for industrial preheating applications. When integrated with multi-effect distillation (MED) or membrane distillation (MD) systems, this configuration enables efficient small-scale seawater desalination for remote islands and maritime applications. Furthermore, the system directly delivers conditional hot air for agricultural applications (greenhouse heating, crop drying) and building heating systems. Previous studies have enhanced dual-channel PV/T system performance through flow channel optimization. However, these improvements fail to address seasonal variations in thermal demand, particularly the year-round utilization of hot air. To address these limitations, this study proposed a novel dual-channel PV/T system for enhanced energy harvesting. The present system features a carefully configured layout with defined structural parameters for key components, including the photovoltaic module, auxiliary equipment, and all pipes. A comprehensive one-dimensional transient model was developed based on an equivalent electrical circuit theory and thermodynamic principles. A grid independence test was conducted to verify the computational reliability of the model. This modeling approach enabled the characterization of the dynamic behavior of PV modules and provided an analysis of interactions between the current and the temperature distribution.Firstly, an investigation of structure parameters was conducted to evaluate system performance under different operating conditions. Material dimensional studies revealed that the air interlayer thickness exerts the most significant sensitivity on system performance metrics. Subsequently, the optimization of air mass flow rate was examined across various solar irradiance levels. The system exhibited peak performance at distinct optimal air flow rates, which scale with solar irradiance: 0.0007 kg s–1 (200 W m–2), 0.002 kg s–1 (600 W m–2), and 0.003 kg s–1 (1000 W m–2). Similarly, the study revealed a stepwise dependence of optimal water flow rate on solar irradiance. For solar irradiance under 300 W/m2, the appropriate water flow rate is 0.004 kg/s. For solar irradiance from 300 to 700 W/m2, the optimal flow rate is 0.008 kg/s. For solar irradiance from 700 to 1000 W/m2, a suitable flow rate is 0.012 kg/s. The proposed system achieves markedly higher thermal efficiency than both single-channel and conventional dual-channel PV/T systems. Although its electrical efficiency is slightly lower than that of the reference systems, the overall performance is superior. Furthermore, the study investigated four operational modes arising from the combinations of air and water flow patterns. Based on the performance evaluation of these modes, a regulation strategy was developed to guide operational adjustments according to energy demands and environmental conditions.The proposed dual-channel PV/T system demonstrates the flexibility in energy output control compared to conventional designs. This research offers a viable solution for high-efficiency solar energy utilization in diverse applications, including building-integrated systems and industrial-scale solar installations. Future work will focus on experimental validation of the numerical model and advanced control algorithms.