Google developed „Project Sunroof“ by connecting Google map that provides interactive maps and satellite view with global solar map that provides average annual GHI (global horizontal irradiance). Solar map is a subset of a larger global solar dataset created by company 3TIER, specialized in assessment and forecasting of renewable energy. Averages are based on more than 10 years of hourly GHI data derived from visible satellite imagery using a combination of in-house research and algorithms published in peer-reviewed scientific journals.
How the project works? First step is entry of home address as base for personalized roof analysis. Project Sunroof computes how much sunlight hits the roof taking into account Google’s database of aerial imagery and maps, 3D roof modeling, shadows cast by nearby structures and trees, all possible sun positions over the year, historical cloud and temperature patterns that might affect solar energy production. Second step is data entry for calculation of solar solution. Project Sunroof recommends an installation size to generate close to 100% of home electricity use, based on roof size, the amount of sun hitting the roof and amount of electricity bill. When discussing solar installation with your provider, the recommended installation size (in kW) is a good starting point for a more fine-tuned estimate of total costs and benefits. Third step is computing of your savings. Project Sunroof uses current solar industry pricing data to run the numbers on leasing, taking a loan or buying solar panels for your house to help you choose what is best for you. It also compiles tax state tax credits, utility rebates, renewable energy credits and net metering to calculate your final costs. The last step is the selection of the installer. The system offers the installers serving your area and those you select get information for making an offer.
The project is still in its early phase with some room for improvement, for example taking into account certain elements such as roof’s inclination or different amounts of shade at different times during the day. So far, the roof exposure to the direct sun can be analyzed by citizens of Boston, the San Francisco Bay area and Fresno. If the prediction turns out to be correct, the service might be available all over the U.S. rather soon, with potential to be spread worldwide. Although we don’t know when the Project Sunroof will be applicable in Europe, G-Solar welcomes this project for several reasons: it is simple to use, it raises the awareness on renewable energy and, most importantly, supports end users by estimating cost effectiveness of PV installation.