Overall energy performance of building-integrated bifacial photovoltaic sunshades with different installation and building parameters in hot and humid regions

Solar photovoltaic (PV) shading systems are of great significance for achieving low-carbon buildings. Bifacial photovoltaics (bPV) is a promising technology that can generate electricity from both the front and rear sides of bPV modules. By integrating bPV shading systems into buildings, more power generation and less building energy consumption can be achieved compared to traditional shading systems. This study aims to integrate and optimize bPV shading systems into the building vertical façades in hot and humid regions, considering varying installation and building parameters. The evaluations of electricity generation and energy saving were conducted based on a typical three-story office building in Hong Kong. The evaluation of electricity generation reveals that the optimal installation condition for bPV sunshades in Hong Kong is south orientation with a tilt angle of 35°. Regarding the width of bPV sunshades, as the width increases, the annual electricity generation per unit area (AEGPA) decreases, but the total annual electricity generation (TAEG) increases. Besides, the bifacial gain of optimized bPV sunshades increases from 3.3% to 6.1% as the wall reflectivity increases from 0.15 to 0.7, while being insensitive to window reflectivity. Similarly, when the window-to-wall ratio (WWR) increases, the bifacial gain decreases. Furthermore, the energy-saving evaluation indicates that the south orientation with small tilt angles and wide sunshades tends to achieve much more energy savings benefits. The findings of this study provide practical guidance for maximizing the power generation and optimizing the design of building-integrated bPV sunshades to achieve maximum energy savings.