Solar power is an abundant, low carbon source of electricity, but historically it has been more expensive than traditional electricity. With solar costs dropping dramatically, many people are starting to ask: does solar power make sense on my rooftop? In my town or state? Since its initial launch in 2015, Project Sunroof has used imagery from Google Maps and Google Earth, 3D modeling and machine learning to help answer those questions accurately and at scale. For every building included in the data, Project Sunroof calculates the amount of sunlight received by each portion of the roof over the course of a year, taking into account weather patterns, position of the sun in the sky at different times of year, and shade from nearby obstructions like trees and tall buildings. Finally, the estimated sunlight is translated into energy production using industry standard models for solar installation performance.