Real Estate Listings Now Include Solar Scores

The digital age is all about information. Two firms that are a product of that movement now provide consumers with a key piece of information about solar energy when they look to buy a home.

In October, the Department of Energy (DOE) announced that Sun Number, a startup that had benefitted from DOE funds to aid in the development of solar-energy technology, has partnered with real estate listing innovator Zillow. The partnership will supply prospective buyers with information about a home’s potential for generating electricity from solar panels.

The Sun Number score rates a home’s solar suitability on a scale of 1 to 100, with the higher score being better. The score is based on a detailed analysis to determine how much roof area is suitable for solar based on factors such as pitch, orientation and size of each roof plane as well as the amount of sunlight the roof receives based on surrounding obstructions, such as trees or taller buildings.

Other factors that impact the score include the local cost of electricity and solar as well as climate and weather conditions. Users can click through on the score in the home listing for access to this detailed information.

Zillow first started providing the scores in August. The score is available on more than 35 million homes throughout the United States in the Zillow database.

The DOE provides funding to solar-energy startups through its incubator program. Since the program was launched in 2007, $138 million in government funds has leveraged more than $3.1 billion in venture capital and private equity investment.

About the Author

Rick Laezman

Freelance Writer

Rick Laezman is a Los Angeles-based freelance writer who has been covering renewable power for more than 10 years. He may be reached at

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