Need some input on using a solar battery charger for my trolling motor. Talked to a couple of people and they feel a solar charger is worthless. Just now ask a man about his and he tells me that is all he uses, he says he has kept 2 batteries charged for the past year on nothing but his solar charger. All he could tell me was it was a GTO model but nothing else. So what size would one need to put on a 12 volt battery? I see they sell from 10watts to 100 watts, sometimes I have electric at my slip but more than not the breaker keeps kicking off, the park mgr says they are going to fix it but it's been like this for a year. So if I wanted to depend on my solar charger only what size would I need to keep my batteries charged? Thanks