In this paper, the performance of an indirect natural circulation PVT system for domestic hot water with refrigerant as the circulating working medium was discussed and analyzed experimentally, including thermal performance, photovoltaic performance, overall efficiency, responding speed, heat exchange state, and temperature distribution at different positions. The influence of different five radiation intensities was tested. The results indicate that the performance is largely influenced by radiation intensity. The response speed of the system is greatly improved. It can complete the start-up within 5 min and maintain stable operation at relatively high efficiency. The superheat degree stays between 3 and 4 °C, which is not affected by the radiation intensity, but the sub-cooling degree of the liquid medium increases with the increasing of radiation intensity. Furthermore, the temperature of the panel all reaches the superheat range, but the superheat degree in the middle of the panel is the largest. The temperature distribution is not uniform, which needs to be optimized further.
Solar energy PVT Natural circulation Domestic hot water
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This study was supported by National Key Research and Development of China (Grant No. 2017YFC0704202).
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