The University of Neuchâtel said Wednesday it intends to appeal a decision by the European Patent Office to revoke a patent it has licensed exclusively to Oerlikon Solar.

The patent office said the patent isn't valid after holding a hearing on Tuesday, a decision that would weaken Oerlikon Solar's attempt to stop a rival's customers from making a type of thin-film solar panels.

In a statement, the head of the university's photovoltaic lab, Christophe Ballif, blamed "a mere technicality in the filing process" for causing the patent office to invalidate the patent. Ballif said the patent will remain valid until the final resolution of the dispute.

Oerlikon Solar has developed a set of factory equipment for making amorphous silicon-based cells, which are then packaged into panels for installation. In 2003, the Swiss company licensed the patent in order to develop equipment for making tandem junction solar cells. A tandem junction cell has a layer of amorphous silicon and another layer of microcrystalline silicon for converting sunlight into electricity. That microcrystalline layer acts as a booster to improve the cell's performance.

The patent describes the method for depositing the microcrystalline layer on glass or glass-like substrates, Oerlikon said. The company believes that the patent makes it the sole legitimate developer of tandem junction solar cells with a microcrystalline layer on glass or related material, a claim that prompted complaints filed with the patent office from companies such as Sunfilm, Q-Cells and Kaneka.

Oerikon filed lawsuit last year against Sunfilm for allegedly infringing on the patent (see Oerlikon Solar Sues Sunfilm). Sunfilm, based in Germany, has bought equipment from Santa Clara, Calif.-based Applied Materials. A win by Oerlikon in this lawsuit could jeopardize the business of a host of Applied Materials customers in Europe and Asia.

"Certainly we see this as a positive sign from the patent side," said Applied spokesman Dave Miller.

Oerlikon, meanwhile, maintained that the outcome of the patent fight wouldn't have a huge impact on its overall business. In a statement, the company said it has a lot of other patents, and even thought the patent provides "an important process step in the?production of thin-film silicon solar modules, the Oerlikon end-to-end solutions?do not depend on this single aspect."

The patent dispute is taking place at a time when customers of both Oerlikon and Applied have begun to produce tandem junction solar panels.

Sunfilm is building a second production line that will be able to produce up to 60 megawatts of solar panels per year. Commercial production from the new line is scheduled for start later this year. The company already is producing tandem junction solar cells and panels from its first production line, which can produce over 60 megawatts of solar panels.

ENN Solar Energy in China said earlier this month that it had rolled out tandem junction solar panels using Applied's equipment.

In Oerlikon's corner, Inventux Technologies in Germany began mass-producing tandem junction solar panels last December. The production line can make up to 60 megawatts of panels per year. Another customer, Auria Solar in Taiwan, also has begun production from a line with a capacity to produce roughly 60 megawatts of panels per year. 

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