Design and experimental evaluation of a parabolic-trough concentrating photovoltaic/thermal (CPVT) system with high-efficiency cooling

The design and performance evaluation of a novel parabolic-trough concentrating photovoltaic/thermal (CPVT) system are discussed in the present study. Initially, the system design and manufacturing procedures as well as the characteristics of the system sub-components are thoroughly illustrated. At a second stage, the findings in regard to the optical quality of the parabolic trough are presented, as obtained through an experimental procedure that utilizes a custom-made measuring device. The device bears a grid of sensors (photodiodes), so that the irradiation distribution on the receiver surface and the achieved concentration ratio can be determined. Besides, the main factors that have a significant effect on the trough optical quality were identified through ray-tracing simulations. The system electrical and thermal performance was subsequently evaluated in a test rig specially developed for that reason. Three variations of the system receiver incorporating different PV-module and heat-sink designs were evaluated and the prototype CPVT system was found to achieve an overall efficiency approximately equal to 50% (44% thermal and 6% electrical efficiencies, respectively) mainly limited by the trough optical quality, however with a very weak dependency on the operating temperature.