New York City Is Latest to Launch Solar Mapping Tool for Building Owners

The 3-D maps enable any building owner to go online and find out how much sunlight hits their roofs

NYC Solar Mapping
Data visualization showing how points are used to construct a 3D model of the city/Credit: SustainableCUNY

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Successful marketing often involves putting a product’s facts — literally — at customers’ fingertips.

That seems to be the philosophy that city officials have brought to their online solar mapping services — and the results have been far reaching, they say.

Since March 2008, when San Francisco first put its map a click away from interested citizens, solar photovoltaic (PV) installations in the city have tripled, from 700 to 2,100 this year.

“[It] is the main solar outreach tool used in San Francisco,” said Danielle Murray, the city’s renewable energy program manager.

That may be so, but many observers say the City by the Bay’s rooftop solar boom has been largely driven by California’s tiered rate system, in which electricity bills rise as people use more power. And, according to Murray, the solar map has averaged a less-than-arresting 70 hits a day since debuting — though she insists this figure belies the project’s impact.

Seventeen other U.S. cities and the German city of Osnabrük have published solar maps on the Web since San Francisco’s site went live, enabling home and building owners to assess the potential of their roofs to generate clean electricity.

The map combines aerial images with calculators and other features to provide owners with facts and figures needed when considering whether to purchase a PV system, such as the pitch of the roof and the amount of shade cast by neighboring buildings.

Most of the maps were developed by Critigen, a technology consultancy based in Greenwood Village, Co., and were partly funded by the Department of Energy’s Solar America Communities Program.

NYC Map Will Be the Biggest

The map of New York City, the biggest so far in terms of quantity of data and geographic area surveyed, is scheduled to go live on June 16, during the fifth annual New York Solar Summit.

Convened by the City University of New York (CUNY), the summit will bring together leaders of city and state agencies, the solar industry and utility Con Edison, with the goal of accelerating solar adoption in the nation’s largest city.

“The map is an important part of this effort,” said Tria Case, who heads the New York City solar map project as director of sustainability for the university. “It’s a tool that building and homeowners, installers, city officials and Con Ed can use.”

The map is exact. During night flights over New Yok in May 2010, a twin-engine plane equipped with lasers captured the architecture of the city. From these images, CUNY’s Center for Advanced Research of Spatial Information created a 3-D model of the city.

“It’s as if we shrink-wrapped the entire city in paper lined with a one-meter grid and got the exact elevation and horizontal location of each square meter,” Sean Ahearn, the geographer who directs the center, told SolveClimate News.

Ahearn said the site incorporates so many bytes of information that it took a supercomputer with 10 processors some 50 hours to generate the map interface.

The website can calculate how much solar radiation hits every square meter of the city — every hour, every day for an entire year. For building owners it means they can size up of the solar energy potential of their rooftops within minutes.

The Web tool is just as useful to installers, its builders say.

“Before making a site visit, an installer can look the property up on a map and advise an owner,” said Kay Schindel, an engineer who worked on the solar map for the city of Madison, Wis.  “The installer might, for instance, believe the house roof is too shaded, but there is an excellent location for a ground installation in the backyard.”

Typically, the maps also estimate annual savings on electric bills, the time it takes to recoup the cost of a solar installation and the yearly reduction in CO2 emissions that a solar system will create.

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 “solar empowerment zones” 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.

“These zones will give us an opportunity to model and study the benefits and challenges of distributed generation and of PV, which is at the forefront of distributed generation,” Mucci said. 

Power from distributed generation is created by the customers themselves, rather than at a power plant at the end of a transmission line. In addition to solar, utility companies like Con Edison may have to integrate large numbers of customers generating electricity by harnessing the wind or burning biomass fuels.

Dispelling Myths, Setting Goals

Observers say the maps also challenge the myth of solar energy adoption in some cities. Many Bostonians think their city is too far north, for instance, while San Franciscans say their city is too foggy.

New York City, with its towering skyline, has its own problem: Almost none of the 350-plus solar systems now installed are visible from the street.

All three cities have worked to remove bureaucratic barriers to widespread solar usage. As the nation’s largest city, New York has probably created the most obstacles. Case of the City University of New York says the June summit seeks to bring together the relevant players — the buildings department, the fire department, solar installers, government officials, Con Ed, financial institutions and business leaders — and agree to a streamlined approval process.

The ultimate goal, she said, is to reduce to 100 days the 8-plus months it now takes to go from deciding to install solar to having a PV system up and running.