what is the logic for saying a five watt solar does not need a controller? I have a 5 w and a 1.5 w. the 5w panel charges a battery that just has a bilge pump connected. the 1.5 panel charges a battery that has nothing connected. At max current of .4 and .125 amp I think the panels will nicely keep the batteries charged considering there is a daily discharge. I'm meeting people that say you should have a controller. I'm confused.