SECTION INTRODUCTION: Manufacturing Equipment & Materials

In today’s photovoltaic industry, the challenges are in many ways the same as any global manufacturing sector – to improve efficiency and quality, reduce costs and optimize the manufacturing supply chain. The IPVEA (International Photovoltaic Equipment Association) continually strives to help its members in particular, and the industry in general, to achieve these goals with a series of initiatives. Key to these initiatives is our partnership with publications, such as Future Photovoltaics, that investigate the latest ways in which research and development can help move forward on commercial goals.

The research in the following paper looks in particular at the cost-per-watt reduction. Among many other elements, cost-per-watt reduction is key for commercial success, and this is being achieved through reduced material cost and higher cell efficiencies. In order to achieve these higher efficiencies, effective passivation of the rear surface of industrial solar cells is required.

While thermally grown silicon oxides provide an excellent level of surface passivation on low-doped p-type surfaces, dry thermal oxidation processes require relatively high temperatures and long process times. To decrease both oxidation temperature and process time, the dry oxidation process can be replaced by a wet oxidation.
Researchers from RASIRC and the Fraunhofer Institute for Solar Energy Systems (ISE) report on using wet oxides grown from purified steam to provide a high level of surface passivation. This is at least comparable to wet oxides grown by the standard pyrolytic steam process, where the water vapor is generated from high-purity gases. In this manner, conversion efficiencies above 20 percent can be achieved.

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