Originally Posted by St. Elsewhere
What you need is a "water tight cable pass-through". Defender has these: Marine Cable Pass Throughs on Sale
Through hulls are generally things that are below the waterline. Your pass-through will be above it. There are also simpler devices. The minimum would be to create a drip loop in the wire that causes water
on the wire to drop off the bottom of the loop with the penetration above it. The hole would be sealed with silicone and SeaDog maks a little stainless fitting that covers the penetration like a shingle.
If you want to do it right for the long term and keep water
out the above works. We have 3 solar panels
and put one of these on when we ran the wiring
and that was 8 years ago and still good to go. We live on the boat 24/7 and sail her hard, around the Carib both east and west, across the Atlantic and now in year 2 in the Med.
Do it right or somewhere down the line expect a problem.