I have solar panels currently hanging in an angle from a utility building, out and over the cars, and hope to extend them with more panels angled into a full carport shape one day; columns at one side, attached to utility building at other, room for one car underneath.
The panels have a 2x4 frame surrounding the exterior, and designed to support each panel from sides and underneath; between each panel & between panel & frame, I used a thin, high-density foam insulation piece. The panels are machined so perfectly that they already make a tight fit when next to each other. These 2x4 frames are exterior, so entire 2x4 was sealed w/ Thompson's before use. These have lasted a few years so far, thru brutal winter seasons & heavy snows, and the
wood hasn't degraded yet.
This insulation sheet, which normally goes under the sill plate for a foundation, and comes in an 8" pink roll, is perfect to cut & fit between the panels and 2x4 frame. You can't see it, if cut right. This blocks most any water that I care about, which is just getting the worst of it away from what's underneath. Most water/snow runs off the down-sloped shape; if a few drops make it through and hits the car underneath, I won't lose any sleep, but I rarely see any water underneath it, anywhere.
Hope this helps ...