Building energy saving of a rotatable radiative cooling-photovoltaic system by alternate utilization of solar energy and radiative cooling

Building-integrated photovoltaic (BIPV) and Building-integrated radiative cooling (BIRC) are recognized as efficient renewable utilization technologies that can promote building energy savings and reduce carbon dioxide emissions. An innovative rotatable radiative cooling-photovoltaic (RRC-PV) system is proposed, which has multi-functions of photovoltaic power generation, radiative cooling power utilization, and overhang shading. The nonstop alternate utilization of solar energy and free cooling energy from the outer space can be realized. The system breaks the constraint of limited building surface areas and has significant meaning for the renewable energy exploit in high-density cities.In this study, the model of the RRC-PV module is developed and validated with experimental data. Rhino and Grasshopper platform are used, and the radiative cooling power is calculated with a self-developed GH_Cpython program. The RRC-PV system is applied to a typical office in Shenzhen with hot summer and warm winter climate. By applying the RRC-PV modules with total area of 1.68 m2, the daytime PV power generation is 361.9 kWh throughout the year, and the nocturnal radiative cooling power utilization is 246.9 kWh. The building energy usage intensity was reduced from 89.7 kWh/(year·m2) to 83.7 kWh/(year·m2), resulting in payback period of less than 6 years.