Image analysis and estimation of rooftop solar exposure via solar ray mapping

A system for determining solar exposure on a roof of a structure, comprising:

• an imaging subsystem to utilize images captured by a camera on an unmanned aerial vehicle (UAV) during a flight pattern executed relative to a structure;
• a ray-path modeling subsystem to model ray paths between modeled locations of the sun relative to the structure and each of a plurality of locations on a surface of the structure;
• and
• an irradiance calculation subsystem to calculate a total solar irradiance on the surface of the structure during a time period in which the sun is modeled as moving from a first location relative to the structure to a second location relative to the structure.

A non-transitory computer-readable medium with instructions stored thereon that, when executed by a processor, cause a computing device to implement operations to:

• conceptually divide a modeled surface of a roof into a plurality of polygons;
• model ray paths between each polygon and modeled locations of the sun relative to the surface of the roof at each of a plurality of different times and days;
• calculate an angle of each modeled ray path relative to the normal of each respective polygon at each of the plurality of different times and days;
• calculate a total solar irradiance on each polygon between a first time and a second time based on the calculated angles of the ray paths between the first and second times;
• and
• calculate a total solar irradiance on the surface of the roof between the first and second times based on the summed total solar irradiance on the polygons on the surface.