Global Solar Energy said Wednesday it will start selling its thin-film cells in July, joining a small group of companies that have managed to bring thin-film solar to market.

The company, based in Tucson, Ariz., has been developing strings of copper-indium-gallium-diselenide (CIGS) cells for about three years. Unlike its competitors, Global Solar doesn’t assemble the cells into glass panels. The company claims that selling the lightweight strings makes it cheaper to transport than glass-encased cells.

The cells can be cut to match a variety of panel sizes and can be adopted into current panel factory lines, directly replacing traditional silicon-based cells, said Jeffrey Britt, Global Solar’s chief technology officer

"We have reached the point where we are ready for commercial partners and we are ready to provide them with strings on a significant quantity bases," Britt said.

Global Solar, founded in 1996, has been making thin-film cells for portable gadgets such as iPods, PDAs and cell phones. But it is jumping into the business of making thin-film cells for larger-scale projects, such as solar systems for buildings, because of its lucrative potential.

In early March, Global Solar said it was opening a 40-megawatt, mass production plant in Tucson, Ariz. Britt said the plant is expected to produce 20 megawatts of the films this year before ramping up to 40 megawatts of capacity in 2009 and 140 megawatts by 2010 (see Competition for First Solar?).

In late March, Global Solar began shipping cells that Britt said are "approaching" the efficiency levels of its prototype cells from its 4.3-megawatt demonstration plant. The cells went to customers, such as German panel-maker Solon, to test the products.

At the demonstration plant, Global Solar was able to produce cells with an average of 10 percent efficiency, meaning the cells converted about 10 percent of the sunlight that hit them into electricity.

Global Solar has also leased factory space from Solon to build a 35-megawatt thin-film production line in Berlin. Production is expected to begin by June next year, according to Britt.

Thin-film solar cells use little or no silicon, the costliest part of most solar cells. They remain more expensive to make on a large scale and less efficient at converting sunlight into electricity than silicon-based cells. But advocates contend that thin-film technology could become much cheaper one day and find new markets, such as building materials and textiles (see Thin-Film Solar Production to Leap Forward).

This potential has heated up the race to bring more thin-film cells to market. Currently only a few key players, like Wall Street darling First Solar (NSDQ: FSLR), has managed such a feat (see First Solar Rides High, Solar Sector Heading For a Shakeout and Thin Films Lead U.S. Solar Production).

First Solar, which makes cadmium-telluride films, reached an average cell efficiency of 10.6 percent at the end of last year, according to investment bank and institutional securities firm Piper Jaffray.

Looking to give First Solar some competition are companies like Miasolé, which plans to ship its first commercial thin-film solar panels to customers by the end of this year, and Nanosolar, which said in December it had begun shipping its commercial thin-film panels to its first customer (see Miasolé Clears the Air and Nanosolar Begins Production).