More CIS for Solar Performance

Just 0.70 Euros per watt
The three East-German companies, Avancis, Johanna Solar and Sulfurcell are also working successfully with sequential procedures for semi-conductor production on their own independently developed lines. Avancis’ CIGS panels, for example, already convert up to eleven percent of light into energy. The Torgau-based company wants to achieve cost reductions through efficiency increases as well as by tripling the manufacturing capacity to 60 MW by 2010/2011. Würth Solar, which, other than the Eastern trio, focuses on coevaporation of CIGS elements, already achieves an average of twelve percent efficiency with modules in its 30 MW factory. And development boss, Bernhard Dimmler sees further optimisation potentials, “We can achieve 14 percent on average.” For this, Würth wants to replace the buffer layer made of cadmium sulphide (CdS), which separates the CIS absorber and the front contact from one another, with a more transparent material. Up to now, the function of the buffer has not been fully clarified. We only know that it is important for the level of efficiency. The search for CdS alternatives is already prospering at Würth: In cooperation with the Berlin-based Helmholtz-Zentrum, the Swabian company has produced small-scale modules with an indium-based buffer with 14.4 percent.

However, the German companies must hurry with scaling up their innovations. International competition is already hot on the heels with its expansion. The German manufacturers could be left far behind in terms of capacity. Japanese company Showa Shell, for example, wants to expand to one GW capacity by 2011. If Würth & Co does not press ahead with the same dimensions in time, they will probably be unable to keep up in terms of costs, as they will barely benefit from a scaling effect connected to a larger production quantity. A similar development is currently becoming apparent on the crystalline solar market: Chinese manufacturers are building giant factories, saturating the markets with cheap silicon modules, pushing the European producers further and further out of the competition. “The level of venture capital, available to companies, is limited in Germany compared to other countries,” explains von Armansperg, citing a reason for the lack of German drive to mass produce. Another reason: Scaling up CIS productions is not an easy task. The companies are still largely producing using prototypical systems. Standards, like Applied Materials or Oerlikon have set with their machinery for thin-film silicon and which encourage mass production, are lacking for CIS. Turnkey suppliers, Centrotherm can ignore the concerns: As a global supplier, it is irrelevant to them who buys their lines.