1. Fraunhofer Institute for Solar Energy Systems ISE, Heidenhofstraße 2, Freiburg 79110, Germany
2. Albert-Ludwigs-University, IMTEK, Georges-Köhler-Allee 103, Freiburg 79110, Germany
3. EV Group, E. Thallner GmbH, Erich Thallner Street 1, Schärding 4780, Austria