Study on a hybrid solar indirect-expansion heat pump system associated the novel mini-channel solar thermal & PV/T panels for space heating

Solar PV/T (or thermal) panels-based indirect-expansion heat pump systems were often applied to deliver space heating for buildings. The paper investigated a hybrid space heating system that comprises the novel mini-channel solar thermal and PV/T panels, as well as a heat pump. These components are appropriately integrated to allow different functional parts of the system to operate jointly or individually, thus creating a low-cost and load-responsive operation that can deliver space heating during winter and generate electricity and hot water during other seasons for a typical northern China rural house. This work was undertaken through a dedicated system design, construction, clear-days based field-testing, and performance analysis. It was found that during the typical-day testing, the mini-channel thermal panels had the average solar efficiency of 50.8%; while the mini-channel PV/T panels had the average solar efficiency of 45.0%, and the whole heat pump had the average Coefficient of Performance (COP) of 4.9. The system made use of multiple energy sources and its energy breakdowns during the typical testing day were 44% from solar and 56% from gas. The system can keep the room temperature at above 18°C throughout the testing period, thus meeting the thermal comfort standard of the house. The research has produced the fundamental data for the mini-channel-based solar thermal and PV/T panels and accumulated the experience of designing a hybrid space heating system applicable to rural houses in cold climatic regions of China, thus contributing to significant fossil fuel saving and carbon emission reduction in the global extent.