National Public Radio: Many old factories around the country now sit dark and empty. But at a once-defunct Polaroid film factory in New Bedford, Mass., the lights are on again and a new industry is rising up inside the ruins of an old one. The company Konarka makes solar panels, but not the kind most people have seen. These are thin, lightweight, flexible plastic sheets, and that enables them to be used in all sorts of new ways. “We make what’s called plastic solar cells; we call it ‘power plastic,’ …