I'm looking at getting a solar panel to keep a battery (possibly dual batteries) charged in my camper trailer to run an Engel 60L fridge and some LED lighting and maybe a 12V stereo setup. I am thinking of about a 120W panel and reg, but found there are a few different types available and was wondering what are the most cost effective ones to get (ie poly chrystalline, monochrystalline etc) and any recommendations for suppliers, and things to look for or other tips.