After staying mum for most of the year, Nanosolar said it has made a leap into mass production and improved its cells' efficiency.

The San Jose, Calif.-based company touted these accomplishments to show that it has made a significant progress since it first announced the start of commercial production in December 2007.

That December announcement has drawn skepticism and even ridicule from competitors and analysts because the company kept refusing to divulge details of its technology, factory capacities or production rate, and it revealed little about customers or projects that would make use of its solar panels.

A Photon magazine article published in January this year criticized Nanosolar for making bold claims but having little to show for since its December 2007 announcement. Photon titled the article, "Nanosolar: No news from the world champion in blowing smoke."

Nanosolar's solar cells make use of a compound of copper, indium, gallium and selenium (CIGS) to convert sunlight into electricity. The materials and its manufacturing process are relatively new to the market, which is dominated by crystalline silicon cells.

The startup, founded in 2002, now said it already began producing its solar cells at its San Jose factory earlier this year. Nanosolar's CEO, Martin Roscheisen, declined to disclose the capacity of the solar cell factory, though back in August 2008 he talked about expanding its manufacturing capability by building a 430 megawatts plant (see Nanosolar Confirms $300M Funding).

The company also said Wednesday that it has completed a 640-megawatt factory to assemble the cells into panels in Luckenwalde, Germany, though this achievement isn't new and is timed to coincide with an inauguration ceremony attended by Germany's minister of environment and other public officials.

Back in February this year, Roscheisen told Greentech Media that the solar panel factory had already been completed and was in operation, though it was running in one-shift mode (see Nanosolar Broke round on 1MW Power Plant, Launched German Panel Factory).

"All tools in our Luckenwalde factory are up and running since the end of last year.  As a result, our latest panels are all being assembled there now as opposed to in our much smaller San Jose panel-assembly line," Roscheisen wrote in an email in February.

Nevertheless, completing the solar panel factory is a big deal for Nanosolar, because its San Jose panel assembly line wasn't fully automated like the one in Luckenwalde. Nanosolar wants to sell its panels to developers of large-scale power plants, so the company has to be able to produce in high volumes and do it cheaply.

Roscheisen declined to divulge the company's production costs. He pointed out in an email that the company has signed $4.1 billion worth of contracts, and named Beck Energy, EDF Energies Nouvelles, AES Solar, Juwi and NextLight Renewable Power among its customers.

That amount of contracts surpassed the roughly $2 billion of contracts announced by fellow CIGS company Solyndra, which broke ground on a 500-megawatt factory less than a mile from its headquarters in Fremont, Calif., last Friday (see Solyndra: Fab 2 Construction Begins).

Nanosolar wouldn't disclose when it is due to deliver on its contracts. The company said it's currently producing its cells and panels at a rate of roughly 1 megawatt per month. The company's panels have received certification from the International Electrotechnical Commission, a validation of the products' performances that is crucial for winning customer acceptance.

Securing bank financing remains a hurdle for the company and its customers, Roscheisen said. The credit crunch has plagued the solar market worldwide over the past year. Convincing banks to finance projects built with newer technologies is a challenge – bankers often prefer equipment by established and larger companies that are more likely to be around to honor its 20-year warranties.

One of its customers, Beck Energy, started building a 1-megawatt project on a former landfill in Luckenwalde last October.  Roscheisen declined to say when the project is scheduled for completion.

Nanosolar has posted two white papers to describe its solar cell technology and compare its panels to those made by First Solar. Tempe, Ariz.-based First Solar makes cadmium-telluride solar panels and is the largest thin-film maker in the world. Both Nanosolar and First Solar make what are commonly called thin films, which use little or no silicon.

The company said Wednesday that its solar cells could convert 16.4 percent of the sunlight that hits them into electricity. The National Renewable Energy Laboratory has confirmed that efficiency, which is higher than figures provided by rival CIGS thin-film makers such as Solyndra, Miasole and HelioVolt (click on company names to see their reported efficiencies).

Engineering efficient solar cells and producing them at low costs is the goal of every solar cell maker. While companies are usually eager to divulge efficiency numbers, they tend to remain mum about their production costs.

The 16.4 percent is the best Nanosolar can produce, though it is generally higher than the average cells that roll out of production lines. The company said the median efficiency of its cells hover between 11 percent and 12 percent.

Nanosolar also claims that when the cells are assembled into a panel, the collective efficiency remains essentially the same. That's a different than the manufacturing processes for the silicon and other types of panels could deliver today. Typically, a solar panel's efficiency is lower than that of its individual cells because the cells don't all perform uniformly when they are put together.

Nanosolar said it sorts cells before assembling them to avoid mixing poor performing cells with the good ones, and that helps to achieve the same cell/panel efficiency.

First Solar said its panels on average have 10.9 percent efficiency. First Solar also is known for being able to make panels cheaply, and has been happy to disclose that its manufacturing cost is about 87 cents per watt.

The company makes its cells by printing CIGS onto an aluminum foil in what's commonly called a roll-to-roll process. The technology can produce cells more quickly than some of the competing methods, the company said.

The aluminum, which isn't expensive, is conductive and serves as the bottom layer of electrode to help ferrying electricity produced by the cells, the company said (see Nansolar's white paper on its cell technology).

In its white paper about its panels, Nanosolar said it encases its cells with two pieces of tempered glass. This approach makes for a more durable panel and larger-sized panels compared with First Solar's panels, which uses tempered glass for the back.

Nanosolar said its manufacturing process allows it to easily make panels of different sizes and power ratings, which range from 160 watts to 220 watts.

The company is introducing panels that are 2 meters in length and 1 meter wide, Roscheisen wrote in an email. First Solar's panels are 1.2 meters by 0.6 meters, with power ratings ranging from 70 watts to 77.5 watts.

Image of Nanosolar CIGS cells via the company.