I have had a solar shed for a few years that powers some outdoor landscape lights 12v. I recently bought 3 100 watt panels in hopes I can run my koi pond pump. It uses about 54 watts. Currently I have a 35 amp battery and an inverter. This pump runs 24 hrs a day and the battery runs out over night ....so is there a device that can use my solar system until the battery discharges to a point and then the 120 grid power can take over automatically?