Experimental analysis and annual energy evaluation of thermal-daylighting-electrical performance of PV vacuum glazing for high-rise buildings

This research presents a comprehensive experiment comparison and annual energy evaluation of the thermal-daylighting-electrical performance of solar photovoltaic (PV) vacuum glazing for practical building applications. A transient coupled heat transfer and power generation model of the PV vacuum glazing is developed to obtain its dynamic temperature distribution and current-voltage curve as verified through experiment. An on-site experiment of the PV vacuum glazing is performed on a testing building to evaluate its dynamic thermal-daylighting-electrical properties in contrast with conventional glazings. A validated simulation model of the PV vacuum glazing is further constructed for application in an actual hotel building to analyze the annual energy performance in comparison with typical glazings. The research results indicate that the coupled heat transfer and power generation model has acceptable accuracy with the mean bias error lower than 4.44 %. The PV vacuum glazing shows a good thermal performance with the solar heat gain coefficient at about 0.194 (PV glazing at 0.546, vacuum glazing at 0.623), the U-value at about 1.06 W/(m2·K) (PV glazing at 5.15 W/(m2·K), vacuum glazing at 1.15 W/(m2·K)), while its indoor heat gain can be reduced by 61.6 % and 67.57 %, respectively. It also ensures good daylighting and electrical performance with a useful daylight illuminance of approximately 72.6 % with a peak power output of 434.41 Wh (power efficiency at 6.95 %). The building energy use intensity using the PV vacuum glazing is about 106.85 kWh/m2·a, lower than the PV glazing, insulating glazing unit, vacuum glazing by 29.88 %, 39.11 %, 40.89 %, respectively. Its annual power generation is about 307.32 MWh accounting for 12.29 % of the total building demand, which is equivalent to about 135.31 tons CO2. The lifetime levelized cost of energy of the PV vacuum glazing is about 1.226 CNY/kW, and it can realize cost recovery in the 14th year if the original cost is decreased to 500 CNY/m2. The developed comprehensive research framework of the PV vacuum glazing provides significant reference and guidance for developing net-zero energy buildings in urban areas.