1. Fraunhofer Institute for Solar Energy Systems ISE Heidenhofstr. 2 Freiburg 79110 Germany
2. SLAC National Accelerator Laboratory 2575 Sand Hill Road Menlo Park CA 94025 USA
3. Research School of ElectricalEnergy and Materials EngineeringCollege of Engineering and Computer Science 32 North Rd, The Australian National University Acton ACT 2601 Australia
4. Laboratory for Photovoltaic Energy ConversionDepartment for Sustainable System Engineering (INATECH)University Freiburg Freiburg 79085 Germany