1. Department of ElectricalMechanical and Industrial Engineering Anhalt University of Applied Sciences Bernburger Strasse 55 06366 Koethen Germany
2. Fraunhofer Center for Silicon Photovoltaics CSP Otto-Eissfeldt-Strasse 12 06120 Halle (Saale) Germany
3. Leipzig University Prager Strasse 36 04317 Leipzig Germany