Before launching Greenspring Energy, Paul Wittemann spent 11 years selling satellite-TV systems to cable users. When he learned in late 2006 that the state of Maryland planned to hike electricity rates—and offer a tax incentive to buyers of solar-energy systems—Wittemann decided to make a change. Over the next six months, he set about educating himself and earning certifications in installing and servicing the latest solar technologies. Greenspring landed its first customer in the fall of 2007; the company has since opened offices in Pennsylvania and North Carolina. Most customers, Wittemann says, aren't as interested in going green as in investing in their homes—and saving money. "Depending on utility rates, a solar system, which costs $30,000 on average, can provide up to an 18 percent return on investment," he says, "something you're not going to get by putting in a new kitchen."