Solyndra is working on a project to install its cylinder-filled panels on one million square feet of rooftop space in Southern California, an executive said Thursday.

Kelly Truman, Solyndra's vice president of marketing and business development, mentioned the project briefly during his talk at Intersolar North America in San Francisco Thursday. But he wouldn't say more about it during an interview afterwards.

Worldwide, there are 50 projects installed or in the process of being erected that use Solyndra's equipment. About 10 of them were demonstration projects while the rest are commercial projects, Truman said.

Back in March, the company touted a 132-kilowatt system atop the Livermore Cinema in Northern California. Truman also showed slides of a 1.66 megawatt project in Germany and a 480-kilowatt installation in Spain during his presentation. Most of the company's business is in Europe.

Fremont, Calif.-based Solyndra is not a project developer, but it makes and sells solar panels and mounting systems that it says can cut down installation time by a third and cost by a half.

The company has attracted a lot of attention for its unusual solar panel, which is made up of 40 tubes in an aluminum frame. Each tube contains another tube on which the light-absorbing layer of copper-indium-gallium-selenide (CIGS) resides.

Solyndra claims that the tubular design allows the CIGS solar cells to make use of light reflected from the rooftop. The spacing between the tubes makes the panel more wind resistant than the conventional flat-panel variety, and the mounting system it has designed is easy to set up because it requires no rooftop penetration, Truman said.

The company, founded in 2005, also has stood out among the roughly eight CIGS companies in the United States for the amount of contracts it has signed and announced (see Solyndra Adds $238M Contract, Brings Backlog Total to $2B). It started commercial production last summer while many of its fellow competitors are still in early stages of commercializing their products.

The $2 billion backlog of deals is a popular subject of discussion at the solar conference. It attracts envy and a heavy dose of speculation about the company's ability to deliver and whether its product could deliver electricity at competitive costs.

"Solyndra looks ridiculously cool, but would it work? I don't know," said Mark Zanoli, managing director of investment banking at JP Morgan, during the conference earlier this week. "That $2 billion is ridiculously appealing that it gets every banker fired up about visiting the company." Zanoli said he personally hasn't been one of them.

Solyndra also hasn't disclosed the efficiencies of its panels. The cells have efficiencies around 12 percent to 14 percent (when rolled flat), which has led analysts and competitors to question whether and why Solyndra's panels are attractive.

With a 12 percent to 14 percent cell efficiency, each panel could have less than 10 percent efficiency. That number is lowered than the majority of flat-plate solar panels on the market today.

Truman, for his part, declined to discuss the installation costs of a system using Solyndra's panels and mounting system, but maintained that critics underestimated the savings Solyndra can achieve through its panel-and-mounting system design.

Discounting the costs of the panels and rack, the cost of setting up the remaining parts of a system could reach 50 cents per watt, Truman said. He wouldn't say how large the system would have to be to achieve that cost.

"We have reduced the balance of system cost that doesn't depend on efficiencies," Truman said. Solyndra's panels have rated power output from 150 watts to 200 watts, he said. Most of them are rated at 191 watts. During the manufacturing process, each tube's performance is tested by placing it against a white background to simulate a white reflective rooftop.

Solyndra began commercial production last summer with a 20-megawatt line, Truman said. The company has equipment to make at least 110 megawatts of solar panels per year, and is ramping up production, he added.

The company also is planning for a 500-megawatt factory near its headquarters, and is close to finishing the final negotiations for a $535 million loan guarantee from the U.S. Department of Energy. The money would be enough to foot 73 percent of the total cost, the company said. Truman declined to say how the company would fund the remaining cost. The plan is to start construction later this year, Truman said.