A hybrid parabolic trough solar collector system integrated with photovoltaics

Abstract

It is challenging to reduce the massive radiation heat loss from the parabolic trough solar receiver and enhance the solar utilization efficiency of the parabolic trough collector (PTC) system. On the basis of the negative thermal-flux phenomenon discovered in the PTC system, a novel PTC system integrated with photovoltaic (PTC-PV) panels is proposed in this study to effectively enhance the thermal performance and solar utilization efficiency of the PTC system. Four modes of the hybrid PTC-PV system are put forward for catching the optimum configuration. The mathematical models of the hybrid PTC-PV system in terms of photothermal and photoelectrical conversions are established. Additionally, a test rig of the hybrid system is built, and the experiments are carried out in an indoor laboratory with a solar simulator. Comparisons between the experimental and simulated results show that the model has an excellent prediction ability. Furthermore, a 12 m-length PTC-PV system using molten salt as heat transfer fluid is studied to validate its thermal, exergy, and overall performance. The results show that the hybrid PTC-PV system exhibits dramatic superiority in overall performance over the PTC prototype system. The heat loss of the solar receiver in the hybrid PTC-PV system is significantly reduced by 44.0 %, and the photoelectrical efficiency of the PV panel in the PTC-PV system is drastically enhanced by 118.3 % compared to that installed on the ground. Moreover, the overall and exergy efficiencies of the PTC-PV system can be improved by 14.3 and 13.7 %, respectively, at the inlet fluid temperature of 580 °C.