Design of PV/TE hybrid power generation device based on thermal switch and its improving efficiency of power generation

Abstract: In order to solve the problem of inefficiency of photovoltaic conversion caused by temperature rise when photovoltaic cell panel generates the electricity after receiving solar radiation, the present paper discussed about a method that the thermoelectric power generation technology could cool down the photovoltaic cell panel, this method was a kind of active cooling mode. However, when the temperature difference between the hot side and cold side of thermoelectric generator was close to each other, the thermoelectric conversion efficiency was too low, which had a negative effect on the device. To solve the above problem, the thermal switch was adopted to control the equipment, the switch would close when the temperature of the photovoltaic cell panel reached the predetermined value, and the heat passed down. On the contrary, the switch was in the off state. Through the control of the thermal switch, the thermoelectric generator could work stably and efficiently in the working range. Meanwhile, it could also improve the adaptive capacity to environment of the device. At the same time, the flat heat pipe had been chosen as the heat transfer unit, using water convection to cool down the system. After cooling the photovoltaic cell panel, not only its temperature would decrease, but also the service life could be extended. On the other hand, the cold side temperature of the thermoelectric generator could also decrease. Firstly, the present paper analyzed the effect caused by different intensity of optical radiation, different panel temperatures and different cold side temperatures in the system. Secondly, the whole experimental platform of system had been established. Last but not the least, the hybrid power generation system had been examined so as to test the property of hybrid power generation equipment which was based on PV/TE (photovoltaic/thermoelectricity) of thermal switch. The result revealed that the efficiency of hybrid power generation equipment was higher than a single electricity generating method included the photovoltaic power generation mode and the thermoelectric power generation mode. At the same time, the gradient utilization of energy could be realized by the equipment. In view of the experimental equipment had been built, the performance of the PV/TE hybrid power generation device based on thermal switch was investigated in two different ways, including the instant property and full-day performance test. The instant property of the PV/TE hybrid power generation device based on thermal switch was tested during 08:00-18:00 on August 27, 2017. The results showed that the efficiency of power generation could reach the peak point of 19.45% and the output of power generation could reach the peak point of 32.15 W. The full-day performance of the PV/TE hybrid power generation device based on thermal switch was tested from August 22 to 27, 2017. The results showed that the average power generating efficiency of the PV/TE hybrid power generation device based on thermal switch could reach 17.72% and its highest point could reach 18.37%. The test place was located in Northeast Agricultural University, Harbin. Finally, the test results showed the electricity acquired could basically meet the power supply needs of testing system of agricultural greenhouse and remote sensor.