You might consider a water
and a deck
mounted socket. The downside to the clam is that it captures the cable and you can't remove it without resealing and do forth. For more permanent mountings this wouldn't matter. My panels
live on the deck and I can easilty take them off in a big blow, and stow them below, or when I feel they might be stolen, so connectors make more sense.
Aside from the clams there are inverted J tubes which are also used