Fully exploiting solar energy with building envelops: Experimental study on an adjustable photovoltaic green facade

Abstract

An innovative adjustable photovoltaic green facade (APVGF) was proposed that combines an adjustable photovoltaic (PV) blind system with a green facade (GF), offering high flexibility, significant energy output, excellent architectural aesthetics, and considerable building energy-saving potential. Experimental evaluations with identical test boxes showcased the system’s multifaceted benefits, including a notable decrease in the average daytime temperature of window glass by 4.2 ℃ and 5.2 ℃ for the GF and APVGF, respectively, with peak reductions reaching 9.7 ℃ and 13.7 ℃. The interior air temperature was reduced by an average of 6.5 °C and 7.7 °C, with maximum reductions of 15.3 °C and 18.6 °C. Additionally, the GF and the APVGF reduced the daytime average light intensity inside the test box by 6837 and 7706 lx, reducing the glare risk. High temperatures and self-shading significantly reduced the power generation efficiency of the PV modules in the auto-adjusting and 30° fixed modes. However, the higher total equivalent irradiance (G_E) received in auto-adjusting angle mode resulted in daily power generation being approximately 17.2 % and 22.5 % higher than that in the 30° and 90° fixed angle modes. The APVGF system’s key innovation is its dual-purpose design: it adjusts the angle of the PV blinds based on the sun’s position and environmental needs, boosting PV efficiency, and it enhances the building’s ecological and aesthetic value with a green facade. This system marks a breakthrough in green building tech and offers a new approach to urban sustainability.