Mapping Rooftop Solar to Make It a Social Norm

When we first covered Google's Project Sunroof, it was already an ambitious project with an optimistic goal: making as easy as possible for homeowners to consider the rooftop solar option. Two years in, Robinson Meyer writes, the tool has expanded its prerogatives even further.

"Project Sunroof will now not only inform users how much sun hits their roof, or how much solar panels would save them per month, but also which of their neighbors have taken the plunge first."

Project Sunroof analyzes satellite imagery to determine where solar panels are located and compile neighborhood data. "Google created the data for this feature in-house, training a machine-learning algorithm on the common appearance of rooftop solar panels and then letting it loose on the cities and towns that Project Sunroof already covers."

According to Kenneth Gillingham, a Yale professor who has studied preferences for solar, peer pressure is paramount. "It creates a social norm around solar panels. When many people have solar panels around you, it's a normal thing to do. You're not going out on a limb by having a company come out and look at your rooftop."