The solar trickle battery chargers are purely for maintaining peak battery level to cars left standing that aren't being used on a daily basis, i.e. left in a garage for a week whilst on holiday, that kind of thing. If you're going to buy a solar panel for topping up your battery for WFP pump use then it needs to be able to recharge your battery at a minimum of 8amps per hour of continuous use so it would have to be a large solar panel and probably a unit to protect it from overcharging as well.