Hi Mike'
I mounted a 10watt panel over the forward hatch by bending a couple of thin bits of stainless to clip behind the hinge. I installed a waterproof socket nearby and fed the wire back to a controller which I bought from Maplin, sadly no longer with us. I dry sail and when the boat is on it's trailer it gets the sun for most of the day, fortunately. This keeps the battery topped up between sails and I know the thinking is a panel of this size doesn't need a controller, but on a sunny day it generates 1amp and charging continuously I feel it can't do the battery (110ah) any good. I normally leave it in place when sailing but sometimes disconnect it and take it below if the sea looks a bit rough!
I also have a small fridge with a Danfoss compressor and this uses less than 3 amps on average, connected to a dual voltage transformer which I plug into shore power when available. However when at anchor I have a 20watt panel mounted on a universal bracket on a pole which I assemble and then I plug this into the charging point near the engine, connected in parallel with the other panel.
Peter (Zephyr)