High-resolution 3D solar potential assessment reveals significant shading-driven overestimation in dense urban areas

• Develop a high-resolution methodological framework integrating LiDAR and satellite data for urban solar potential assessment. • Reveal 17.63 % overestimation in 2D solar potential assessments without considering 3D shading effects. • Quantify energy equity disparities using Gini coefficients in dense urban contexts. • Propose actionable strategies for equitable solar PV planning in high-density urban areas. Accurate assessment of urban solar energy potential is critical for sustainable energy transition but remains challenging due to complex 3D structural shading effects often overlooked in conventional models. This study introduces a novel framework integrating high-resolution LiDAR-derived 3D urban models, satellite-based solar radiation data, and an optimized ray-tracing algorithm to quantify shading, sky occlusion, and reflection dynamics at the city scale. Applied to Hong Kong, a high-density metropolis, the framework reveals that traditional 2D assessments systematically overestimate rooftop solar potential by 17.63 %, primarily due to unaccounted urban morphology effects. Spatial analysis demonstrates significant overestimation in dense urban cores (392.13 kWh/m 2 on Hong Kong Island; 305.63 kWh/m 2 in Kowloon) versus lower-density regions (200.53 kWh/m 2 in New Territories). Furthermore, the Gini coefficient for individual-level solar access increases from 0.69 to 0.73 when incorporating 3D effects, highlighting exacerbated energy inequalities in densely populated areas. Validation against ground stations shows the model reduces RMSE by 18.6 % and MAPE by 29.3 % compared to conventional approaches. These results underscore the critical need for 3D urban solar assessments to optimize photovoltaic placement, mitigate shading losses, and address spatial-energy inequities. The framework provides actionable insights for urban planners and relevant stakeholders to enhance solar accessibility through strategic building design, open-space integration, and equitable renewable energy policies, thereby advancing sustainable and smart city development.