Dfroman

Thank you for the reply. Yes, I am using backtracking. I have attached the PVsyst results from both V6.52 and v6.63 for your further review. Dennis

Hi All, Yes I am using backtracking. I am trying to understand why there is a difference in the Near Shading: Irradiance Loss of -1.7% in v6.52 verses -9.1% in v6.63. I have examined everything from preferences and hidden preferences through the shading scene looking for any setting that could account for such a large difference in the simulated results. This is a Single Axis Tracker Grid Connected project. Do you have any insight on where to look? Thanks in advance