Simulation of a novel curved photovoltaic (PV) window improving the annual daylighting and building energy performance simultaneously

Building integrated photovoltaic (BIPV) windows impact building performance by balancing daylighting availability, visual comfort, solar power generation, and building energy consumption. Optimizing this balance is crucial for improving overall building energy efficiency and indoor environment quality. This study introduces a novel curved photovoltaic window design aimed at increasing daylight transmittance while maintaining the same photovoltaic area as a flat PV window. The annual daylighting availability, visual comfort and building energy performance of three types of flat/curved PV windows (180°, 120°, 0°-flat) in a reference office room was comparatively studied across five different climate zones in China (Xiamen, Harbin, Nanjing, Kunming, and Beijing). The PV model was validated by the experimental data. The results showed that the room with curved PV windows had significantly higher daylighting availability compared to flat windows, with the growth rates of the spatial useful daylight illuminance ranging of 3.94%–4.78% and 5.56%–5.94%, respectively, for the curved PV windows at central angles of 120° and 180° across different climate zones. The 120° curved PV windows achieved the lowest net energy used intensity (Net_EUI), suggesting the advantages of curved PV windows and proposed the existence of an optimal curvature for achieving the lowest Net_EUI.