Vera Cole is president of the Mid-Atlantic Renewable Energy Association, a group arguing against proposed rules in Pennsylvania that would put stricter limits on how much grid-connected solar power homeowners can produce on their property. Jeff Brady /NPR hide caption

itoggle caption Jeff Brady /NPR

In Del Norte, Colo., Public Works Supervisor Kevin Larimore shows off solar panels that provide electricity for the town's water supply. Despite generating its own solar energy, the town is still at risk of a blackout if its main power line goes down. Dan Boyce/Inside Energy hide caption

itoggle caption Dan Boyce/Inside Energy

Solar sponge: The top layer of graphite soaks up the sun's energy in tiny holes. When drops of liquid fill the holes, the water quickly evaporates. (The beaker looks hot, but the water below the sponge is cool as a cucumber.) Courtesy of George Ni/MIT hide caption

itoggle caption Courtesy of George Ni/MIT

The Solar Impulse takes off from Moffett Field NASA Ames Research Center in Mountain View, Calif., Friday, as a team member rides an electric bike alongside the plane. AFP/AFP/Getty Images hide caption

itoggle caption AFP/AFP/Getty Images

The Solar Impulse, a solar-powered plane, flies over Switzerland. The makers will be journeying across the U.S. this spring, hoping the flight helps challenge assumptions about what solar technology can do. Courtesy of Solar Impulse hide caption

itoggle caption Courtesy of Solar Impulse

May 26, 2010: President Obama tours the Solyndra solar panel company with Executive VP of Engineering Ben Bierman. Pool/Getty Images hide caption

itoggle caption Pool/Getty Images