Solar-cell developer Suniva said Tuesday it had bagged $50 million in a second round of funding to expand its business and build a manufacturing plant in Georgia.

In total, the Atlanta-based startup has raised $55.5 million in two rounds of venture capital. Investors include New Enterprise Associates and Advanced Equities, which co-led the financing, as well as The Goldman Sachs Group's subsidiary Cogentrix Energy, H.I.G. Ventures and Quercus Investments.

Founded in 2006, Suniva is a spinoff from the Georgia Institute of Technology's University Center of Excellence in Photovoltaics. The center's founding director, Ajeet Rohatgi, is also Suniva's founder and chief technology officer.

Based on Rohatgi's research, Suniva thinks it has figured out a way to lower the cost of makingsolarcells from silicon and to boost the amount of sunlight the cells can convert into electricity.

For the most part, the company is keeping a tight lip on how it plans to do this.

"The patents are around cell design, processes around the use of materials and reducing the number of manufacturing steps," CEO John Baumstark said.

And although Baumstark claims Suniva's approach cuts back on silicon, a key ingredient to making solar-electric systems, he wouldn't say how much.

Efforts to reduce material use in solar, such as Suniva's, increasingly have caught investors' attention as the silicon shortage has squeezed company margins (see Could China Steal the Solar Throne?, Silicon Shortage Has Big Impact, Silicon Starvation and Panelists Debate When the Silicon Shortage Will End). To deal with the issue, some companies have been racing to bring thin-film solar, which uses little or no silicon, to market (see Thin-Film Solar Production to Leap Forward, Thin Films Lead U.S. Solar Production and, HelioVolt on Nanosolar's Heels).

For example, German solar company Ersol said Monday its thin-film efforts got a 48 million euro ($71 million) boost. In exchange for the backing, U.S. private equity firm Ventizz will get nearly 50 percent of Ersol's thin-film unit. And on Friday, Germany-based startup Odersun said it had locked up €61 million ($89 million), €40 million ($59 million) from a second round of financing and €21 million ($31 million) in grants, to build a second thin-film factory.

Others have turned to concentrating solar, which take sunlight from a larger area and uses lenses or glass to direct and concentrate it onto smaller solar cells.

In January, Mountain View, Calif.-based SolFocus installed its first array of solar cells in what will be a 3-megawatt project in Spain. And Germany's Concentrix Solar installed 12 of its solar-tracking systems for a Spanish project, according to Gunther Portfolio.

Despite the hype around thin films and concentrating solar, the sectors still face challenges.

For example, thin films tend to have lower efficiency than conventional solar panels. And concentrating solar faces issues of durability because it has more parts than traditional solar systems.

So far, few companies working on thin-film or concentrating solar have been able to deliver the goods on a large scale and at an economical price.

But the silicon shortage has limited production of traditional solar-power systems, although some insiders think that could be changing as soon as this year, and a report by the Prometheus Institute and Greentech Media projects that thin films will grow to make up 20 percent of the market by 2010.

Still, Suniva is betting on the silicon-based systems that make up 93 percent of the world market for solar today, Baumstark said. The technology is proven and Suniva thinks it has the key to making the technology more efficient and cost-effective.

Suniva has one task: "to produce the highest-efficiency cells at lowest manufacturing cost," Baumstark said.

Today, the company claims its cells are 18 percent efficient -- meaning they convert 18 percent of the sunlight that hit them into electricity -- and plans to surpass 20 percent in the next two to three years. Traditional solar-electric cells currently offer between 15 to 20 percent efficiency, according to the U.S. National Renewable Energy Laboratory.

But Suniva will have to contend with competitors like SunPower Corp. (NSDQ: SPWR), which already has commercial cells that boast 22 percent efficiency and which aims to cut costs in half by 2012.

Baumstark said the company wasn't ready to disclose its cell costs, but said Suniva is competitive with coal-fired electricity during times of peak demand, which is when the highest prices are paid.

"In the next two to three years, we hope to be at grid parity at a dollar per watt," he said.

Suniva is still deciding between two possible sites near its home base, but expects to begin shipping its cells in the fourth quarter. The company also anticipates bringing in $10 million in revenues this year and turning a profit next year with $100 million in sales, Baumstark said.