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On August 17th, Google announced Project Sunroof, a tool that lets homeowners easily visualize their rooftop solar availability and potential savings.

It is currently only available in limited areas (near San Francisco, Boston, and Fresno), but a nationwide rollout is on the horizon.

Project Sunroof’s Automatic Rooftop Solar Analysis

Google Project Sunroof
Given an address, Google Sunroof will visually display rooftop solar availability and shading.

Project Sunroof makes it much easier to estimate whether a home is a good fit for solar. A homeowner interested in solar simply has to enter his or her address and Sunroof will automatically calculate and display a graphic that shows how much sun that rooftop gets.

From there, Google offers a list of local installers who advertise with them. DIY types can also purchase and install their own solar systems if the roof is good fit. If there isn’t good rooftop coverage, Unbound Solar can help potential buyers see if their property has space elsewhere for a ground-mounted array — give us a call at 1-800-472-1142.

How Project Sunroof Works

How does Sunroof work? Google combines diverse solar datasets:

  • Google’s database of aerial imagery and maps
  • 3D modeling of rooftops
  • Shadows cast by nearby structures and trees
  • All possible sun positions over the course of a year
  • Historical cloud and temperature patterns that might affect solar energy production

The data is processed and combined into an easy-to-use, Google Maps-like interface. Done manually, each step of this process would take a homeowner hours of data collection and analysis.

Sunroof’s automation makes the process dramatically easier.

Solar Analysis Before & After Project Sunroof

Before Sunroof, there were similar tools for estimating solar rooftop potential. However, they required the user to manually draw in their roofs and didn’t take into account nearby obstructions (trees, buildings, etc.) that could cause rooftop shading.

NREL PVWatts Roof Analysis
Before Google’s Project Sunroof, similar tools (such as NREL’s PVWatts) required users to manually outline their roofs.

Now, using the 3D aerial data gathered by Google for this project, even trees and other obstructions are accounted for and factored into their analysis:

Example of how tree shading affects rooftop solar. The areas in purple are too shaded for panels.
Example of how Project Sunroof depicts tree shading. The area in purple is too shaded (by the trees towards the bottom) for panels.

Next Steps

Roof looking good? Then you’re ready to proceed to the next steps. From our Getting Started with Solar guide:

  1. Lower your energy use! The more power you can save and the more efficient your appliances, the fewer panels you’ll need — and that means more savings for you.
  2. Decide what kind of system you need, whether that’s grid-tied, off-grid, or something in between.
  3. Determine the proper size for your grid-tied system or off-grid system.
  4. Give us a call at 1-800-472-1142 and we’ll help you pick out the best system for your needs.

If you’re confused by any of the steps, feel free to call us and one of our Solar Technicians can guide you through the process.

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