Owners of a relatively modest home in San Francisco can learn, for instance, that a 2.5-kilowatt system can each year avoid releasing carbon emissions equivalent to driving their car 2,100 miles, or taking 467 trips across the Golden Gate Bridge.
Links embedded in the maps also provide information for how to qualify for federal, state and local incentives and for finding an installer. On some maps, users can share their solar experiences with others.
Nearly every site stresses the importance of adding solar panels only after owners have retrofitted their homes or buildings to be as energy-efficient as possible.
Maps Promote Energy Efficiency
In Boston, PV installations have increased five-fold since the city launched its map less than three years ago. Bradford Swing, director of energy policy for the city, believes the map was a driving force behind the boost, but says its main contribution may lie in getting people to think more broadly about energy efficiency.
"The map is now part of Renew Boston," explained Swing, a new program aimed at "greening" residential and commercial buildings. "We have set an ambitious goal of reducing greenhouse gases by 25 percent by 2020. As important as solar is, we cannot do that with solar alone."
He continued: "For a lot of people, going green means solar, but we want these owners to recognize first that energy efficiency is the key to environmental responsibility."
Using a grant from the Department of Energy, Swing said that Boston is working with 100 homeowners to reduce the costs of installing PV systems, though it comes with a catch: To participate, homeowners have to commit to an energy audit and then retrofit their homes according to the audit recommendations.
San Francisco is also planning ways to maximize its map's utility, Murray said. Later this year the city expects to add information about solar water heating and a calculator that will help visitors determine the financial and environmental benefits of using the sun to provide hot water. Next year San Francisco plans to add a wind feature to the map.
NYC's Map: A Tool for Con Edison
New York City's map will eventually incorporate information that none of the other maps have yet included: the electricity footprint for every building in the Big Apple.
The numbers will be available on the "back end" of the map to Con Edison, which operates the largest electrical grid in the country, to help the utility identify the best locations for solar installations and plan for projects.
As part of its solar push, New York City and Con Edison have already identified three "" in Brooklyn, Queens and Staten Island. These wide swathes of the city were selected based on their peak electrical usage and their potential for PV installations, among other factors.
Three ombudsmen serve the zones by conducting outreach programs, particularly to owners of buildings with large roofs. One condition favoring accelerated adoption of solar in New York City, officials say, is that a small number of developers own a majority of the commercial buildings. The ombudsmen will also help expedite the solar approval process for any building owner throughout the city.
Given that solar power is usually most abundant when the demand for electricity is highest, Con Edison says it hopes it can reduce or at least delay the need for new substations and other infrastructure upgrades in certain neighborhoods, while making the overall grid more reliable.
"While we are still learning how much energy solar can reliably provide to our system, we believe widespread adoption will reduce carbon emissions and displace the need to run older in-city peaking plants, which are typically higher in emissions," John Mucci, Con Edison's vice president of Manhattan Electric Operations, told SolveClimate News.
The solar empowerment zones will also be used to test ways to strengthen the grid by making it smarter. PV installations in the zones will include data monitoring systems, which will provide the utility company, as well as the owners, with real-time information about electricity generation and consumption.