Size matters in solar.

• Position: Triangle

To have a bright future, solar energy must be made as inexpensive as traditional sources, and Semprius Inc. thinks it has developed technology that can achieve that. The Durham-based company makes the world's most-efficient solar panels, which convert 33.9% of the energy in sunlight into electricity; according to independent tests. Traditional panels use solar cells--the mechanisms that absorb sunlight--made of silicon. Semprius' are gallium arsenide, more expensive but more efficient than silicon, which has a maximum efficiency rate of slightly more than 20%. That allows the company to keep prices competitive by making each cell small. The breakthrough put its panels among MIT Technology Review's 10 most-important technological milestones of 2012.

Founded in 2005, the company developed its technology with a $3 million grant from the U.S. Department of Energy in 2010. Since then, venture-capital firms have invested $40 million, and German electronics giant Siemens AG bought a 16% stake in June 2011. "That was a springboard to take it from a research-and-development operation to a full commercial-production company," says Russ Kanjorski, Semprius' vice president of business development. In September, the 65-employee company began production at a new $89.7 million, 50,000-square-foot plant in Henderson. It plans to add 100,000 square feet and increase its workforce to 250 within five years. The private company would not disclose revenue.

It supplies panels to Siemens, which announced plans in October to sell its solar business. That, Kanjorski says, doesn't affect the conglomerate's stake in Semprius. Still, it's lining up other major customers. In November, it won a contract to supply solar panels for an electricity-generation demonstration project at Edwards Air Force Base in California. If the project is cost-effective, it could mean expansion to other bases. "That's really a great opening step to build business with the Department of Defense," Kanjorski says.

Outpacing the neighbors Raleigh tops the other Tar Heel metros on Washington, D.C.-based Brookings Institution's ranking of the largest 300 metro economies in the world based on performance. The list weighs gross-domestic product and employment growth between 2011 and 2012. RANK GDP PER EMPLOYMENT GDP GDP PER CAPITA CHANGE CHANGE CAPITA Raleigh 109 0.1% 24% $58.6 billion $48,925 Durham 118 1.0 1.9 36.1 billion 69,248 Greensboro 146 1.0 1.5 40.0 billion 54,163 Charlotte...