Google's Project Sunroof Expands to All 50 States

Posted by Tom Denham

Apr 11, 2017 12:50:26 PM

For homeowners and potential homeowners who have never had an energy efficient home, calculating the projected energy costs can sometimes be confusing and challenging due to different projections.  But now there is a new tool that can help.

Google announced recently that its online tool to assist homeowners in calculating energy savings from rooftop solar installations has now expanded to all 50 US states.  Approximately 60 million buildings have already analyzed by the program.


Project Sunroof is Google's attempt to remove some of the guesswork, combining aerial images from Google Maps with 3D modeling of the roof and even taking into account sun position, weather patterns and shade from nearby objects.

Project Sunroof also uses Google Earth to calculate the amount of sunlight received by each portion of a roof over the course of a year, using the estimated sunlight to determine energy production using industry standard models for solar installation performance.

From this information, Google can calculate how many hours of usable sunlight any roof receives along with how much energy would be available from the installation of solar panels. It can then estimate the resulting energy production based on current solar industry pricing and calculate costs and savings involved for potential projects.

Until this year, Project Sunroof was only available in Massachusetts and Northern California.

A side benefit of the project has been the collection of data that shows how rooftop solar is doing in the United States. 

According to the new data, 79% of all rooftops analyzed are technically viable for solar, including 90% of homes in Hawaii, Arizona, Nevada and New Mexico. States such as Pennsylvania, Maine and Minnesota are just above 60% in terms of rooftop PV viability.

Houston boasts the most solar potential of any US city in the Project Sunroof data with an estimated 18,940 gigawatts of rooftop solar generation potential annually. Los Angeles, Phoenix, San Antonio, and New York follow Houston for the US cities with the most solar potential.

The program also allows homeowners to compare loan, lease, and purchase options for solar panels.

For those interested in the projections for a project, here is the link:

Topics: Renewable Energy