I ran the wires from my solar
panels in through a plastic wire feed-thru that I purcgachesed on Amazon. Since my panels are mounted on feet, the raise them about 1" above the top of the trailer, I was able to mount the feed-thru under a panel so it doesn't stick out. I used 3M 5200 sealer, from Home Depot, to seal the wires. Since I didn't want any more holes in the roof, I mounted the feed-thru using VHB tape and 3M 5200 around the side to make sure that no water got under the feed-thru. I not have over a 1,00 miles towing with the panels, in rain, snow, and the like with no leaks
or problems. I do still check the panels and feed-thru before i leave on a trip.