Systems, methods, and computer-readable media are described herein to model divergent beam ray paths between locations on a roof (e.g., of a structure) and modeled locations of the sun at different times of the day and different days during a week, month, year, or another time period. Obstructed and unobstructed divergent beam ray paths are identified. Unobstructed divergent beam ray paths contribute to the calculation of a solar irradiance value for each location on the roof. Divergent beam ray paths, such as cones or pyramid ray paths, allow for sparse or lower-resolution spatial and/or temporal sampling without sacrificing obstacle detection.