Design and performance test of concentration solar PV/TE compound power generation system

Abstract: In the 21st century, the intensive use of fossil fuels has inevitably brought extreme damage to our living environment. The air pollution of many cities is grave, and the global greenhouse effect is increasing unknowingly. All those problems have had a tremendous impact on human production and life, which also make it urgent to solve energy problems. Solar energy is one of the most promising, the most realistic, the most renewable and cleanest energy sources that can be exploited on a large scale in the world today. With the increasing environmental pollution and the increasing scarcity of energy, the development and use of solar energy have become an urgent task for human development. But, the efficiency is low, and there is a waste of heat energy. Therefore, in order to solve the problems about large-scale energy consumption of conventional energy resources in modern greenhouses, lower solar energy utilization efficiency and waste of waste-heat energy, based on the photoelectric conversion and the photothermal conversion, a concentration solar photovoltaic(PV)/thermoelectric(TE) compound power generation system was designed. Photovoltaic cells use the photovoltaic effect principle to generate electricity. The parabolic concentrator converges solar energy to the surface of photovoltaic cells and enhances solar radiation intensity. The thermoelectric cells are attached to the back panel of photovoltaic cells, and the thermoelectric cells are used to simultaneously convert the excess heat generated by photovoltaic cells to electricity energy. A triangular heat pipe is treated as heat transfer element, and a certain amount of water is used to effectively transfer the remaining heat. The following objectives have been accomplished: Some of the heat generated during the operation of photovoltaic cells was used to increase the temperature of hot side on thermoelectric cells; the other heat was transferred to heat storage tank by the convection of water in heat pipe and reused in heat storage tank. In order to test the electrical performance and thermal performance of this compound system, the corresponding electrical/thermal mathematical model was established in this paper, and the energy conversion of the system was analyzed to obtain the effect of different solar radiation intensities and different flow quantities on the system. At the same time, the system's test platform was set up, and annual tests were conducted in spring, summer, autumn and winter. Tests were conducted from 09:00 to 15:00 when the intensity of solar radiation was the strongest on the test day. The results show that the electrical efficiency and thermal efficiency of concentration solar PV/TE compound power generation system are greater than those by single power generation method, so the gradient utilization of energy can be realized by the system. During the winter test, the electrical efficiency of this compound system could reach 20.98%, the thermal efficiency could reach 39.81%, and the energy efficiency could reach 32.5%. It can be seen that the concentration solar PV/TE compound power generation system has better power property than a PV-TE hybrid power generation system without concentration solar energy. Moreover, the power obtained by operating this system can be supplied for environmental monitoring and lighting systems of the greenhouse. Especially in winter, the heat energy obtained can provide heat for the growth of crops in the greenhouse.