I saw this product on the BTBRV (Big Truck Big RV) Youtube channel and purchased it when I bought my rig a few months ago. I finally had the alignment of time off and weather to install it. The panel attaches via magnet to your pin or any other horizontal surface. The magnets are very strong and it can be left in place even when towing. The panel is rated to produce 15 watts. I live in S. Oregon and we have a fairly sunny climate, but my pin faces NE so it does not get full sun at any time during the winter. I decided to test it on an overcast day to see if it would work, and at mid-day it was producing 5 watts, which should be enough to trickle charge the batteries.
Installation was easy enough, I attached it to the pin and fished the wire from the cutout for the pin to the battery compartment. The fishing was the most time consuming part, but I got it in and attached it to the batteries. It seems to be working fine. Batteries are fully charged so I will watch their level over the next couple of weeks to see if they maintain. The manufacturer recommends disconnecting the battery from your rig to remove parasite draw, but I left mine attached as a test. Here is a link to the website but I purchased through Amazon
https://www.duravolt.net/collections...wheel-trailers