1. CIEMAT, Plataforma Solar de Almería (PSA), 04200 Almería, Spain
2. CIESOL, Solar Energy Research Centre, Joint Institute, University of Almería, CIEMAT, 04120 Almería, Spain
3. Deutsches Zentrum für Luft-und Raumfahrt (DLR), Institute of Solar Research, 04005 Almería, Spain