SeriesInformation ; 23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 2023-2026 ; Abstract ; SCHOTT Solar Thin Film has successfully scaled up its production technology for a-Si/a-Si tandem cells from 0.6 m² to 1.4 m² (Gen 5) module size in Jena. The Jena fab with a capacity of 33MW/a started production in late 2007 and ramp up was completed in mid 2008. While small area R&D cells deposited in a large area PECVD tool achieve 10.4 % initial efficiency, the best module yields 123 W initial power which corresponds to 9.1 % initial aperture efficiency. Light induced degradation of a 1.4 m² module is demonstrated to be only 16.3%. Thus, more than 100 W stabilized power can be projected. The ASITM module design takes PV-system requirements into consideration. The low voltage module design with high maximum system voltage allows high power per PV-string, comparable to c-Si based PV-installations. ASITM modules submitted to damp heat after 14 years outdoor exposure do not reveal any power losses, thus demonstrating high reliability and long-term durability. During summer, a small PV-system based on ASITM 95W modules yields remarkable performance ratios higher than 90%, compared with 80% for the c-Si based reference system.