1. Department of Civil Engineering, University of Rome “Tor Vergata”, Via del Politecnico 1, 00133 Rome, Italy, Department of Hydraulics, Transportation and Roads, University of Rome “La Sapienza”, Via Eudossiana 18, 00184 Rome, Italy, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland, and Solar Technology Laboratory, Paul Scherrer Institute, 5232 Villigen, Switzerland