Experimental and numerical study of a reversible radiative sky cooling PV window

Transparent envelopes, such as windows, are usually the weak points of building thermal insulation and responsible for the tremendous cooling/heating energy consumption in the building sector. An innovative reversible radiative cooling PV (RRC-PV) window was proposed, which combined the radiative sky cooling and photovoltaic window technologies. It was capable of generating electricity from incident solar energy and reducing the indoor cooling load in the daytime whilst providing natural cooling at night by dissipating heat to outer space through atmospheric window. The thermal and electrical performances were tested. Simulation program was developed with MATLAB and validated successfully. Further, year-round energy performance was evaluated based on the TMY dataset of Shenzhen. The indoor heat gain was effectively reduced by utilizing RRC-PV window instead of common clear glazing window. The total reduction was 208.16 MJ/m2 per cooling season. Meanwhile, the beneficial indoor heat gain during heating season was unfavorably reduced. With the electricity generation taken into consideration, the annual comprehensive energy saving potential was as large as 264.23 MJ/m2 over common clear glazing window under hot summer and warm winter climate of Shenzhen, China. Thermal and energy performances of RRC-PV window could be favorably improved in regions with plentiful solar irradiance and cleaner atmosphere. The local climate and comprehensive energy performance should be evaluated before practical application of RRC-PV window with the proposed methodology. Future research and development of radiative cooling materials would enhance the building energy saving and contribute to the neutral carbon cause.