Photos: MIT's solar house under construction

On the fringe of the Massachusetts Institute of Technology campus in Cambridge, Mass., volunteer students and advisers are building a home powered entirely by the sun. This 800-square-foot building, which started to go up in earlier this summer, is their entry in the Department of Energy's 2007 Solar Decathlon. As part of the competition, 20 contestants from around the world will assemble solar homes on the National Mall in Washington, D.C., in October. MIT's building is called MIT Solar 7 because it is the seventh time MIT has built a 100 percent passive solar home since 1939.