Experimental study on the heat transfer performance of the PVT ventilated roof as heat exchanger for heat pump system

A novel PVT (photovoltaic and thermal technology) ventilated roof as heat exchanger for heat pump system is proposed. The roof was not only the exterior skin of a building but also was the evaporator for the heat pump system and the power generator. It integrated the function of the windproof and waterproof, power generation and the heating supplement. In structure, an array of the PVT modules and the ventilation passage were laid over the original roof, which changed the heat transfer mechanism of the building envelope by hindering the absorption of the solar radiation and changing the direct contact environment of the original roof as well as outputting electrical and thermal energy and furtherly affect the building energy consumption. To study the heat transfer performance of the proposed PVT ventilated roof and its influence on energy consumption, an experiment was performed in typical weather conditions in summer and winter. This experiment focused on the temperature distribution of each layer in the PVT ventilated roof, the airflow characteristics in the ventilation passage, the temperature delay and attenuation, the heat gains and the energy consumption. The results indicated that the PVT ventilated roof was effective for maintaining a stable indoor thermal environment as well as reducing energy consumption in summer, while its energy-saving effect in winter was moderate.