Hello all, I have some questions to ask for my Dad`s fishing boat. He wants to install a solar panel to keep the two group 24`s batterys charged up for one 500 bilge pump.He has a selector switch 1/all/2/off. His first question is : what size panel would he need? second: He would like to be able to hook the two batterys up separately to the controller ,so he can turn the selector switch off , that way nothing will be on ,but the bilge pump. Can this be done? and what type of controller would he need? third: will the controller charge them separately or both together? We are looking at the controllers and panels on wholesalesolar.com The morningstar, prostar model 15m , looks like it would work,with the four battery cable hookups or is there something for less money that would work also ? Thanks for any information on this . chet