Batteries in store energy generated by roof-top solar panels. Batteries are constantly recharging, and two factors affect battery operation time: Outside temperature. A fully-charged 16kWh battery is enough to power your house for 4 cloudy days at 32’F or for more than one week of cloudy days at 49’F. Amount of consumption. If all of your appliances and systems run simultaneously, you will drain your battery in one day. Or you can be economical, and use your energy efficiently. Larger battery energy can be chosen for northern regions and very remote places.