Oerlikon Solar extends its lead in thin film silicon technology with new TCO 1200 plant
Pfäffikon SZ, Freiburg, 21 June 2007 - in good time for the Intersolar fair at Freiburg, Oerlikon Solar presents the fully developed TCO 1200 coating plant. TCO stands for Transparent Conductive Oxide. In thin film silicon modules, these light-transmitting layers act both as electrodes and "light traps" and are therefore key components. Oerlikon Solar is the world's only plant manufacturer to now offer this process stage with its own technology, meaning it masters the entire production process for solar modules of thin film silicon. "We are now in a position to supply turnkey factories for the manufacture of thin film silicon modules," says Detlev Koch-Ospelt, head of Oerlikon Solar. One of the first factories of this new, industrial kind is in the process of starting production at ersol Thin Film in Erfurt. Independent market research institutions concede that thin film technology has the greatest potential for the future.
TCO layers play a central role in thin film solar modules of silicon for two reasons. Firstly, they have to show exceptional electrical conductivity in order to transport the solar electricity with as little resistance as possible; secondly, this film traps the light and passes it through the photoactive silicon layer. The optical absorption of the TCO layer must be low, the so-called light-trapping potential as high as possible. Ultimately, these factors determine the performance of the solar modules and directly reduce the cost per watt peak.
Until now, there has been no supplier of a TCO plant on the global market. "With our known TCO technology, we extend our technological lead over our competitors," says Oerlikon CEO Dr Uwe Krüger. In the past, manufacturers of thin film solar modules bought the TCO-coated glass panes directly from the glass manufacturers. For that reason, it was impossible to perform selective optimization of these key components of thin film solar modules. "We have now closed this gap with our own plant technology and can therefore further develop the performance of thin film silicon modules together with our customers," says Oerlikon Solar chief Koch-Ospelt.
The new plant from Oerlikon Solar is based on an LPCVD process (Low Pressure Chemical Vapour Deposition), using low-cost, environmentally friendly zinc oxide instead of the commonly used fluoride doped tin oxide. Low deposition temperatures of approximately 200 °C impose less stress on the substrate and also permit more substrate options. In the deposition process, diethyl zinc and steam react at subatmospheric pressure to form zinc oxide. Under suitable process conditions, films with a thickness of two micrometers can be formed with an excellent surface texture with no need for post-processing. Oerlikon conducts direct testing of this quality during the production process by sampling TCO-coated glass.
The TCO 1200 becomes part of the fully automated factory design FAB 1200, with which Oerlikon Solar integrates all production technologies and processes to create a turnkey solar factory. As presently the world's only plant builder, Oerlikon Solar masters the central steps - TCO coating, thin film silicon coating, laser structuring, final assembly - with its own technologies and can supply industrially mature production solutions. The first solar factory of this new generation has been built at ersol Thin Film GmbH in Erfurt in the past few months and starts production in the next few weeks. The thin film modules, which with cost advantages of up to 30% are substantially more economic than conventional solar cells, can therefore be put into use on a broad front. Independent market research institutions predict growth rates of well over 50% for thin film silicon technology in future. "With our production solutions and innovations such as the TCO 1200, we are seeing to it that thin film silicon technology can become further established on the market," says Oerlikon CEO Dr Uwe Krüger.