Earlier in the year a friend and I built and mounted frames for the panels on our rigs. We used 3/16 x 2 " aluminum angle stock and 1/8 flat stock for the upright cross braces. Total cost was 200 bucks for each build. The frames are 30 ft long by 35 in wide and all the struts/braces/mounts were fitted to avoid the a/c units, vents, etc. In addition, we utilized residential solar mounting rails, bolted to the top of the frame and the panels then affixed to the rails.There is less than an inch clearance from the panel to the top of the highest a/c unit. I was concerned with the wing/lift effect so I set my son on the issue. He is an mechanical engineer and his buddies are aeronautical engineers/pilots. (They are USAF test pilots) Their opinion was no additional support was needed and a potential for lift at horizontal plane was zero. My friend chose to mount his panels perpendicular to the roof. I followed him from Yuma to Tuscon and there was no movement in the panels that I could detect. Mine are mounted parallel to the roof and there has been no shifting either. My buddy affixed mounting brackets in place using gorilla glue and screws, then installed a new roof over them. They are never coming off.. I used 3M High bond tape. Don't recall the specs off hand but shear factor was something like 1100 lbs/sq in and tensile strength was in the area of 700 lbs/sq in. My total mounting brackets total 144 sq/in. If I hit a bridge I will probably peel my roof off before losing the rack.