I've bought my first panels, nine used 545w bifacials, and one or two have these marks on them which I'm assuming is hard water spots from being stored. The panels don't look like they were ever installed, no tooling marks or screw scuffs. Just some rash on the frames from being moved around, some mud, and a few scuffs on the glass that I hope I can polish off. I cleaned the spot in the middle left of the image with CLR lightly but it didn't make a difference. Before I try vinegar, automotive rubbing compound, or anything else I figured I would ask here first. Thanks for any help you can offer. This is the worst one of the 9 and will probably just be my spare. All panels are putting out full power. Thanks for any advice...