Two years after it launched Project Sunroof, Google is it only has expanded to every single state, and is now is now crunching data for 60 million rooftops across the country. And the potential is sky high. According to Project Sunroof, which uses data from Google Maps and Google Earth, combined with 3-D modeling and machine learning to determine the solar electricity potential of individual roofs, 79 percent of the rooftops it’s analyzed are viable for solar, meaning technically they get enough sun to be able to accommodate solar panels. In sunny states like Hawaii, Arizona, New Mexico and Nevada, 90 percent of rooftops are viable, according to Google, whereas it’s around 60 percent viability in states like Pennsylvania, Maine and Minnesota. The city with the most solar potential is Houston, Texas, with an opportunity to generate close to 19 gigawatt-hours of electricity from solar rooftops per year.