So these are solar charge controllers at the best price. If protecting your battery is more important to you than what a solar panel can offer you, go for it. I will be returning them in favor of some MPPT controllers. Originally bought six and connected in parallel with six 12v batteries which in turn were connected in series for a 72v electric tricycle with six 100w solar panels. They seemed to give me about half the charge I was getting from the chargers and really choked off the power available while driving. I tried contacting the manufacturer who basically said they weren't designed for the use I supplied them for. Spring. Connected one of the 24 volt MPPT units to 4 remaining Sunforce units and was already seeing 4 volts more available under load than with 6 Sunforce units and only spent about $8 more.