Oerlikon Solar said Wednesday that it has filed a lawsuit in Germany against Sunfilm, claiming that Sunfilm has infringed on its patent for manufacturing thin-filmsolarpanels.

Oerlkon Solar, which develops and sells equipment for making thin-film solar panels, contends that Sunfilm is violating its patent for its micromorph tandem cell technology. Oerlikon, a Swiss firm and a leader in the market, acquired the technology from the University of Neuchatel in Switzerland in 2003.

Last year, Sunfilm announced its plans to enter the thin-film solar panel business. Since then, the German company has set up a production line and bought equipment from Santa Clara, Calif.-based Applied Materials. The production line is scheduled to go online next month. Sunfilm said in May that it has ordered more equipment from Applied Materials for a second line.

“Oerlikon’s intellectual property is being knowingly infringed upon by Sunfilm AG,” said Oerlikon Solar’s CEO Jeannine Sargent in a statement. “Our IP represents the cumulative work product of thousands of scientists and engineers for over 20 years, including millions of dollars in investment.”

The lawsuit reflects the growing competition in the thin-film solar market, which is much smaller than the one for solar panels made with conventional silicon. Making thin-film panels at a large scale is more difficult and expensive, though the technology promises to be cheaper and more efficient at converting sunlight into electricity one day. Thus far, only a handful of thin-film panel makers have brought their products to market.

Oerlikon sent Sunfilm a warning letter earlier this year about Sunfilm’s plans to make large, 5.7 square-meter tandem junction solar panels, which are made of amorphous and microcrystalline silicon layers on glass. According to Sunfilm, the two layers improve the ability of the panels to absorb and convert sunlight into electricity.

Sunfilm representatives couldn’t be reached for comment on the lawsuit Wednesday.

The lawsuit  raised questions about whether Oerlikon will also take legal action against its competitor Applied Materials (see Green Light post). An Oerlikon spokesman, Burkhard Boendel, said there is no plan to do so.

Applied Materials spokeswoman Patricia Zepeda Vera declined to comment.

The patent focuses on the design and engineering of the panels, Oerlikon’s Boendel said. The equipment that is used to make panels is just one piece of a complex manufacturing process.

“Irrespective of who supplies the equipment, Sunfilm’s decision to make tandem junction solar cells infringes on our license,” Boendel said.

Instead, Oerlikon is going after module makers. Several of them, including Sunfilm, have disputed Oerlikon’s patent by filing their objections with the European Patent Office. Sunfilm filed its notice with the patent office in March 2007. Other companies in dispute are Q-Cells in Germany and Kaneka in Japan.

Oerlikon filed the lawsuit against Sunfilm Tuesday in the German District Court in Düsseldorf. The Swiss firm is asking the court to stop Sunfilm from making the panels. Oerlikon has declined to say whether the company is pursuing monetary damages.

In the manufacturing equipment business, more Oerlikon systems are deployed than those from Applied Materials, said Travis Bradford, president of the Prometheus Institute and a partner of Greentech Media.