1. Fraunhofer Institute for Solar Energy Systems (ISE); Heidenhofstrasse 2 79110 Freiburg Germany
2. SCHMID Group; Robert-Bosch-Strasse 32-34 72250 Freudenstadt Germany
3. Laboratory for Photovoltaic Energy Conversion; University Freiburg; Georges-Köhler-Allee 105 79110 Freiburg Germany