Want to know the cost of going solar for your rooftop? MIT spinout Mapdwell has mapped out solar potential for entire cities, providing a cost-benefit analysis. On its satellite-map website, businesses and homeowners can click on an individual roof to receive information about installation price, energy and financial savings, and environmental impact.

Phys.org reports that since 2008, installed solar capacity in the United States alone has grown 17-fold, from 1.2 to 20 GW, according to the US Department of Energy, but there's a need to understand if the costs outweigh the benefits of installing photovoltaic systems in every building.

Each rooftop is covered with color-coded dots that represent open areas for solar-panel installation. They range in color from bright yellow—representing the highest yields—to orange, to brown.

So far, Mapdwell has mapped eight cities across the US, including New York, San Francisco, and three in Massachusetts—Boston, Cambridge and Wellfleet—as well as a few cities in Chile. It expects to expand to all major metropolitan areas in the US by year's end. [Phys.org]