Energy efficiency analysis of a photovoltaic-thermal system with parabolic trough collector

The results of computer modeling for the energy parameters of the low-temperature photovoltaic/thermal system with a parabolic trough concentrator (CPV/T-PTC) and a hybrid head receiver are presented. A novel design of a hybrid heat receiver is proposed, in which high-efficiency solar cells are located in areas of maximum solar flux from the concentrator. This ensures a uniform distribution of the solar flux over the solar cell surface, thereby increasing their efficiency. Numerical modeling is carried out using Fortran-based software, which is based on a comprehensive coupled 3D thermo-fluid mathematical model and a MCRT/FVM numerical algorithm. The developed mathematical model is validated by comparing the obtained numerical results with analytical results for a test problem. The CPV/T-PTC system with water as the heat transfer fluid (HTF) is used in the simulation. The temperature and energy parameters in the heat receiver for different flow regimes are systematically investigated. It was discovered that the HTF flow regime determines the HTF outlet temperature and is a key parameter for evaluating the energy benefits of the CPV/T-PTC. The maximum HTF outlet temperature of 20.5°C was observed for the laminar flow at Re = 1743. This is explained by the significant influence of conductive heat transfer between the HTF and the heat receiver wall. For the CPV/T-PTC of the given design, the optimal overall efficiency of 51.4% is achieved for laminar flow, while the overall HTF thermal efficiency 22.3% and overall solar cells efficiency 29.1% are at their minimum values.