Solar energy potential evaluation of multi-scale urban building surfaces under complex shading: A multi-dimensional analysis

Driven by global energy transition and sustainable development needs, exploring the solar energy potential of urban building surfaces in complex environments has become crucial. However, current assessments of urban solar potential often overlook the significant potential of building facades under complex shading conditions and lack comparative studies on the heterogeneity of urban spatial structures and solar potential at different urban scales. To address this gap, this study innovatively developed a high-precision, multi-dimensional framework for assessing urban solar energy potential. Using Changsha, Wuhan, and Nanchang as representative samples, the study reveals the solar energy potential and shading rate distribution characteristics of urban building surfaces. The findings indicate: (1) The shading rate of rooftops is the lowest. The distribution trends of total available area and total effective solar irradiation across the three cities are highly consistent. In all cases, rooftops have the largest values, followed by south facades, west facades, east facades, and finally, north facades. (2) Low-density buildings, such as public office and community buildings, exhibit higher solar capture rates (0.8–1.0) and greater energy meeting utilization threshold ratios. High-density buildings (such as residential buildings and commercial complexes) show the opposite characteristics. (3) Urban spatial structure significantly impacts solar energy potential, with cities exhibiting similar spatial structures often displaying comparable solar energy potential. The analytical framework developed in this study can be extended as a universal tool to assess the photovoltaic potential of urban building surfaces globally, thereby providing scientific support for optimizing urban energy structures and promoting low-carbon development goals.