I'm no expert on solar, but the firm I work for installs it. First of all you mention 3 pin, are you referring to a blue plug? If so, the solar panels would make the plug pins live, if it was unplugged from the site power supply. Also I doubt the structure of a static caravan roof would take panels. I'm a touring caravaner, and to be honest I've never noticed any statics on the sites with solar panels.