Elevating solar potential of buildings with facade integration in Chinese cities

Building-integrated photovoltaics (BIPV) presents key strategy for urban decarbonization by enabling localized electricity generation on rooftops and facades. Urban building stocks offer substantial spatial potential for solar energy harvesting. However, existing studies have primarily focused on rooftop photovoltaics, and there is a lack of national-scale assessments that simultaneously consider rooftops, facades, facade orientations, and spatial heterogeneity across cities. This study integrates 3D building footprints from multi-source geospatial data to derive rooftop and facade areas, then applies the PV_LIB model with ERA5 solar irradiation data to simulate hourly generation for 361 Chinese cities. Key findings reveal an annual electricity generation potential of 13,518 TWh from building surfaces across a 159,672 km² target area. Notably, façade-integrated photovoltaics (FIPV) can increase the total power generation of BIPV systems by up to 60% compared with rooftop-only photovoltaic systems. To further explore the multifaceted value of this potential, this study conducts city-level spatial analysis across energy, environmental, and economic dimensions. Results from Moran’s Index demonstrate that economic potential exhibits the strongest spatial autocorrelation among Chinese cities, revealing a clear north-south gradient pattern. Furthermore, an assessment of the urban photovoltaic power generation potential across different orientations reveals that rooftop-integrated photovoltaic (RIPV) and south-facing FIPV deployments optimize economic efficiency, reducing levelized cost of energy by 30%. compared with the full BIPV system. This optimization strategy enhances both energy and economic performance, offering clear guidance for BIPV planning in cities.