We recently acquired a caravan and it had a cheap Chinese solar controller. I was curiously to what was is it so here is a quick tear down
As there is no inductor around the solar mosfets this can only do average current control (if it attempts it) and probably just a voltage cutoff for the charging of the batteries.
Only 2 MOSFETs have thermal pads on them which are on the output load which are badly wedged against the back painted steel plate. The other 4 MOSFETs are for the solar input and have no thermal pads. Something that should be noted is that if any of the tabs (Drain) of the MOSFETs manage to break through the thin paint barrier on the back plate they can short to each other or to whatever the controller is mounted on and put the full voltage of the solar panel into the system.