50 state Project Sunroof: 79% of all rooftops in the US have enough unshaded area for solar panels

By Joshua Hill, 10 March 2017 on Clean Technica

Google’s has announced that its revolutionary Project Sunroof tool is now able to provide a reliable estimate of how much sunlight a given rooftop might receive in all 50 US states, up from 42 states nearly a year ago.

The last we heard from Project Sunroof, it was revealed that it had been expanded to provide data to 42 states across the US, up from 10 states only a few months earlier. Project Sunroof started as one of Google’s 20% projects — projects Google employees can work on in 20% of their time at Google, which sometimes then get branded as a Google product with the company’s full backing. Project Sunroof uses imagery from Google Maps and Google EARTH, 3D modelling, and machine learning to estimate how much sunlight a given rooftop receives, helping to answer how much energy a given rooftop could produce if it had solar panels.

Visualization of solar potential at the Googleplex in Mountain View, CA.

Google announced on its The Keyword blog this week that Project Sunroof is now providing data for all 50 US states, and according to Joel Conkling, product manager, the expanded data has shed some light (get it?) on some interesting insights about the potential US solar industry:

  • 79% of all rooftops analyzed are technically viable for solar, meaning those rooftops have enough unshaded area for solar panels.
  • Over 90% of homes in Hawaii, Arizona, Nevada, and New Mexico are technically viable, while states like Pennsylvania, Maine and Minnesota reach just above 60% viability.
  • Houston, TX, has the most solar potential of any US city in the Project Sunroof data, with an estimated 18,940 gigawatt-hours (GWh) of rooftop solar generation potential per year. Los Angeles, Phoenix, San Antonio, and New York follow Houston for the top 5 solar potential cities — see the full top 10 list in the chart below.

“If the top ten cities above reached their full rooftop solar potential, they’d produce enough energy to power 8 million homes across the US,” Conkling said.

Sample of Project Sunroof solar energy potential map