1. Smart Grid, Fraunhofer Institute for Solar Energy Systems ISE, Freiburg, Freiburg im Breisgau, Baden-Württemberg, Germany
2. The University of Applied Science, Trier, Rheinland-Pfalz, Germany
3. The Reiner Lemoine Insitute (RLI), Berlin, Germany
4. The Polytechnic University of Catalonia, 08036 Barcelona, Barcelona, Spain