The Significance of the Fluid to PV Thermal Coupling in a CPC PVT Collector

Abstract

Photovoltaic thermal hybrid solar collectors (PVT) allow the additional use of heat, while generating electrical power by a photovoltaic absorber. Currently, most commercial PV-T products focus on the cooling of the PV cell only and thereby on maximizing the electrical energy output. However, this thermal yield is not usable in most applications, due to its low temperature. The presented collector concept is designed to increase the temperature of the thermal output by concentrating sunlight and thereby minimizing the heat losses [1,2].Former research on unglazed PVT collectors showed the need for improvement of the poor thermal coupling of the PV cell to the heat carrier fluid [3]. The proposed presentation focuses on this part aspect of optimizing the fluid to PV thermal resistance. A poor thermal coupling leads to a high PV cell temperature and thereby to electrical efficiency losses. Vice versa, the lower fluid temperatures lead to thermal efficiency and exergy losses.The concept of low concentrated sunlight on the PV cell allows the reduction of PV cell material by a factor 2 to 3, and thus, the cell cooling via full surface direct flow inside the PVT absorber.