Mapping tool projects potential savings from solar

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Mass Innovations, From The Beacon, Summer 2013

Cambridge has introduced a mapping tool designed to give homeowners and businesses a precise estimate of the savings they could expect if they were to place solar panels on their property.

The tool, known as Mapdwell, draws on aerial images that cover roughly one square meter each, creating a more accurate estimate of a site’s potential energy yield than is typically available, according to John Bolduc, the environmental planner in the city’s Community Development Department.

“It basically calculates the amount of sunshine that falls on every square meter on a roof over the course of a typical year,” Bolduc said, noting that it takes into account the shade cast by trees and buildings, as well as solar radiation that reflects off other surfaces.

“With that, you get a pretty good estimate of the electricity you can generate,” he said.

Visitors to the Mapdwell website ( ) can zoom in on almost any building in Cambridge and view potential costs and savings. Figures include applicable federal and state tax credits and Massachusetts Clean Energy Center rebates, as well as solar renewable energy credits. The overall cost to the owner, and the years it will take to pay off the initial investment, are prominently displayed.

Municipalities can pay Mapdwell a one-time fee to cover mapping and implementation costs; the fee ranges from $15,000 for communities of fewer than 30,000 residents to $100,000 for a city the size of Boston or larger. The city or town also pays a hosting and maintenance fee, which for Cambridge is less than $2,000 per year.

Bolduc estimates that roughly 1 percent of the city’s peak energy needs are generated through solar power. With the more refined mapping, however, it’s conceivable that solar could eventually supply one-quarter of the city’s overall energy needs.

“Being able to see this graphically really does make a difference in understanding the possibilities,” Bolduc said.

Mapdwell grew out of work that Eduardo Berlin did as a student at Harvard’s Graduate School of Design. Later, Berlin and his advisor moved over to MIT, where the solar tool was developed.

An initial version of Cambridge’s mapping tool was enhanced through the use of LIDAR, a laser technology that sends out rays of light in contrasting frequencies to create maps not only of grounds and buildings but also features such as water and vegetation. The sharper resolution leads to what Berlin describes as a much more accurate prediction of energy yield, within a range of plus or minus 3 percent.

“It allows you to generate a 3-D model of a whole urban sample, which you couldn’t otherwise do,” Berlin said. “It basically does this all at once.”

For more information, contact John Bolduc at (617) 349-4628.
Written by MMA Associate Editor Mitch Evich