I bought this Schumacher solar panel along with a 12V Schumacher SPC-7A solar charge controller so I can keep it connected to the car battery for a long time. Time without worrying about charging. The output on this panel is reversed so it will not work with the SPC-7A as the connectors are molded and the polarity cannot be reversed without cutting the wires. I hope it's a manufacturing defect, otherwise it's really bad product planning at Schumacher. After purchasing the Battery Tender 5-45W Auto Solar Controller and two additional Battery Tender ring terminals, I was able to swap the plus (+) and minus with ease. (-) wires connected to the controller and then everything worked. This solar panel puts out 19-20v on sunny days and works fine once I figure out the polarity issue.