The integration of solid-solid phase change material with micro-channel flat plate heat pipe-based BIPV/T

In this paper, the influence of the solid-solid phase change material on the novel micro-channel flat-plate heat-pipe–based building integrated photovoltaic/thermal system has been investigated, which has been expected to store the excess heat, enhance the overall efficiency of the system and maintain the stable photovoltaic temperatures. The proposed system was divided into two parts, i.e. the outdoor part formed by flat-plate glass, photovoltaic panel, micro-channel flat-plate heat pipes, solid-solid phase change material layer and insulated material, and indoor part including the storage tank, water pump and storage batter. The experiments were conducted at the Guangdong University of Technology, China, to investigate the thermal and electrical performance of the proposed system. When the simulated radiation was at 300 W/m2 and water flow rate was at 600 L/h, the maximum average thermal, electrical and overall efficiency were found at 52.9%, 7.9% and 60.8%, respectively, when the xenon lamps were turned on, and the maximum average efficiency of 86.6% were found when the xenon lamps were turned off, indicating the most appropriate working condition of the proposed system due to the thermal storage and release of the solid-solid phase change material during the system operation. Compared with the previous studies of the conventional building integrated photovoltaic/thermal systems, it was found that the overall efficiency of the system averagely increased 5–30% and the daily water temperature difference of the system averagely increased 1.8–10.5℃, indicating that the solid-solid phase change material can significantly increase the thermal efficiency of the system. Practical application The proposed micro-channel-flat-plate-heat pipe based BIPV/T (MCFPHP-BIPV/T) system with SS-PCM will be potentially used in buildings to provide amount of electricity and thermal energy. The generated electricity will be used by the residential electrical devices or connected to the grid, and the thermal energy can be used for hot water, even for space heating and cooling. The proposed building-integrated system can be assisted in realising the targets of energy saving and carbon-emission-reduction in buildings.