Other authors have developed sophisticated algorithms to automatically separate out roof planes and evaluate solar potential for them. I used out of the box tools.
Each color represents a range of about 30 degrees aspect. Light green = 129-209, light blue = 209-239 .
Each color represents a range of about 3 degrees of slope. Overall, LIDAR data was too coarse for precise slope and aspect values on an individual roof scale, but these tool were effective for identifying roof surfaces that are likely good candidates for solar collectors