Advanced photovoltaic thermal collectors

The solar irradiance received by the solar cell is partially lost as heat, which carries negative effect on its voltage and in turn, its generated power. This trapped heat within the photovoltaic module is considered waste energy. Hence, techniques to extract this heat to utilize it for thermal loads, such as water heating or drying, are presented throughout the literature. Most prominent technique is the hybrid photovoltaic thermal collector. This device will serve in cooling the solar cell and hence improving its efficiency during operation. Meanwhile, it will absorb the heat and transfer it into a working fluid. The fluid could be utilized directly or indirectly for thermal loads in moderate and low temperature range applications. The type of working fluid highly affects the photovoltaic thermal performance and its physical design. This paper tracks the development of working fluids and analyzes highly efficient photovoltaic thermals from the literature. Moreover, a lengthy discussion on state-of-the-art photovoltaic thermal systems is presented and recommendations for future works are listed as well.