Assessing sunlight conditions in urban environments is crucial, as high-quality natural light is essential for human health and well-being while supporting the production of clean and affordable energy. This systematic review examines the current state of research on solar access in urban and neighborhood contexts, identifying key variables and the impact of urban morphology on indoor natural light levels and outdoor solar energy potential. Using the PRISMA protocol, 202 articles were selected, categorized based on thematic and spatial classifications, and their validation methods critically assessed. Key findings from the reviewed articles regarding the impact of urban morphology on solar access are presented and categorized by theme. Finally, the dependent and independent variables in the studies and the validation results were analyzed. The findings indicate that most studies at the urban scale have focused more on outdoor solar energy potential, with fewer studies examining indoor natural light conditions. Building density emerged as the most frequently investigated morphological parameter. Additionally, the review highlights the scarcity of studies that simultaneously consider indoor and outdoor spaces and jointly assess indoor-outdoor solar performance. Although approximately 25% of the studies included validation procedures, direct comparisons were challenging due to the need for standardized validation protocols.
