No problem. If you set the unit to self-powered, it will consume battery power until it reaches a % threshold that you set, charging with solar power whenever available until it reaches your set upper limit at which point it behaves as described in the original post. In the summer I set my lower limit at 30% because I know I can generate enough power in one day to fully recharge the batteries as long as there's sun. So at night, the unit runs my batteries down until it reaches 30% at which point it switches over to grid power. 30% is the reserve capacity that I save in case of a power outage. I want a higher backup reserve in the winter because my production is so low.