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• A large scale PVT direct-expansion heat pump system is designed. • Triple generation of electricity, heating and domestic hot water. • Equivalent net heat energy is proposed to evaluate the energy production. • Photoelectric conversion efficiency increased by up to 25.0%. • The heat pump of the large scale system has an average COP of 4.96. The comprehensive utilization of photovoltaic and solar-thermal (PVT) is an important approach to achieve the carbon peaking and carbon neutrality goals, and can realize the generation of electricity and thermal energy cleanly and efficiently. In order to satisfy the basic living demands including electricity, space heating and domestic hot water of Chinese rural residents, a large scale direct expansion PVT heat pump (DX-PVT-HP) system used plate-tube evaporator has been proposed in the present paper. An experimental platform with a solar panel installation area of 32.47 m2 is installed on the roof of a dormitory in Hefei, and its operation characteristics including electricity and thermal performance are field tested and analyzed in winter. The data indicates that during the operation of the heat pump, the cooling effect of the plate-tube evaporator on the solar panel can maximum increase the photoelectric conversion efficiency by 25.0% in comparison with that of the conventional solar panel. In the process of heating 1500 L water from 5.5 °C to 45 °C on a sunny day, the average coefficient of performance (COP) of the system reaches 4.96, and the power generation of the system is greater than the power consumption. Finally, the concept of equivalent net thermal energy is proposed to unify the output of electricity and thermal energy to evaluate the comprehensive performance of the system. The results demonstrate that it is feasible to adopt the designed PVT heat pump system to meet the basic living needs of rural residents. [ABSTRACT FROM AUTHOR]

Chinese Kang is widely used as heated bed and for heat recovery of cooking stove in Northern China. However there are main drawbacks of indoor and outdoor air pollutant generation and heavy demands on solid fuel handling. A novel combined Kang system, which integrates solar Kang and solar air collector, is here proposed. Experiments were conducted to examine the alternative operating modes: (i) only solar air collector in service, (ii) only solar Kang in service, and (iii) both solar Kang and solar air collector in service. The results show that these three modes behave differently and have distinct effects on room thermal environment in winter. When this pollution-free system operates under the third combined mode, the room temperature increases significantly and the vertical temperature gradient reduces. The Kang surface temperature increases and its uniformity is improved. It is also found that the room air temperature is closely related to the Kang surface temperature. Furthermore, most of the time the thermal environment meets the occupant need. This paper reports the experimental work and investigates into the effects on indoor thermal environment as in rural residences in Northern China. [ABSTRACT FROM AUTHOR]