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MIT Tool Gives the Cost of Installing Solar Panels on Any Roof in Your City

How good is your roof for solar power?

The world, it seems, is falling in love with solar energy. Recent years have seen the increasing adoption of solar power around the world as an alternative energy source for everything from individual homes to the entire energy grid, with the United States' solar capacity having grown to 24 GW, a more than a 17-fold increase since 2008. Part of this rapid growth for solar infrastructure is the result of markedly more efficient solar energy cells, but in spite of these recent technological advances, transitioning to solar power still doesn't make sense (at least economically speaking) everywhere.


Installing photovoltaic systems can be pretty pricey, and home- and business-owners have to engage in a complex cost-benefit analysis to see if transitioning to solar power is an economically sound idea. The "pain-in-the-ass" factor of such calculations alone might be enough to turn people off of the idea of contemplating installing a photovoltaic system, so the folks at MIT came up with a solution: Mapdwell.

Mapdwell maps the solar potential of entire cities by doing a cost-benefit analysis for every rooftop to determine if installing solar panels on that rooftop is worth the investment. All you do is enter your address into the program, and it will tell you the expected installation costs, the number of years it will take to earn back this investment from your photovoltaic system, the amount of carbon offset by the installation, as well as incredibly detailed installment specs such as the optimal panel tilt and the number of panels that could fit on the roof.

At the moment, Mapdwell has only mapped eight cities across the US as well as a handful of cities in Chile, but they plan to have mapped every major US metropolitan area by the end of 2016.

This could prove to be an incredibly useful tool in promoting a transition to solar energy at both an individual and community level. The choice to go solar is often an individual one, insofar as some roofs are better for solar than others (north facing roofs, for instance, get less sunlight than roofs facing other directions). Nevertheless, Mapdwell also provides statistics on the solar yield for entire cities, which could be a useful metric when municipalities are trying to decide whether to promote solar energy.


In this sense, not every city is equal when it comes to how much they should be investing in solar. Boston only has about 1.5 GW of untapped solar potential whereas New York City has upwards of 11 GW of solar potential, which would be the equivalent of planting 185 million trees in terms of offset carbon emissions.

To make these maps, Mapdwell used LiDAR equipped planes which use reflections from lasers to map terrain. This data is then fed to Solar System, an online mapping platform developed at MIT, which Mapdwell's co-founder, Christoph Reinhart, says provides greater accuracy and resolution than previously existing solar maps.

Indeed, the resolution on the Mapdwell maps is so high that when you enter an address, the rooftop of that address will be layered in color coded dots indicating available rooftop space and the optimal placement of solar panels for that particular roof.

Mapdwell has already demonstrated that it is an effective tool in convincing people to transition to solar power. Having readily available information about the cost of photovoltaic installations has proven to make potential buyers more likely to commission a photovoltaic system, according to Reinhart.

"You come to a site, only to be very sure that the site's good," said Reinhart. "Then half the time the owner says yes because they already know from Mapdwell how much it's going to cost. This is where we want to go forward in cities."