An experimental study of the thermal performance of a novel photovoltaic double-skin facade in Hong Kong

Abstract

Ventilated building-integrated photovoltaic (BIPV) facades can not only generate electricity at the locations of buildings themselves but if designed optimally, such facades can also reduce the respective heat gains and heat losses in summer and winter via the building envelope. The development of a novel ventilated BIPV double-skin facade (DSF), constituted by a see-through amorphous silicon (a-Si) PV module and an inward opening window, is reported in this paper. In order to enhance ventilation, an air-flow duct, 400mm in depth is situated between the outside PV module and the inside window. This ventilation design can remove much of the waste heat generated by the PV module energy conversion processes, and thus bring down the operating temperature of the solar cells. Infrared thermal imaging was adopted in relation to the ventilated PV-DSF to visually demonstrate this ventilating effect. It was found that the air temperature at the outlet louver is higher than that at the inlet louver by 2.2–2.3°C. The thermal performance of PV-DSFs operating in different modes was studied and compared. The results showed that the ventilated PV-DSF provides the lowest solar heat gain coefficient (SHGC), while the non-ventilated PV-DSF better reduces heat loss. Based on the experimental results, the optimum operation strategy for the PV-DSF under different weather conditions has been determined and proposed. This novel PV-DSF is more suitable for sub-tropical climates because it results in a much lower SHGC than that of a low-e coating DSF.