Batteries store the energy you produce. You can draw power from your battery to run your appliances at any time. In grid-tied systems, a battery provides backup power to keep key appliances running during a power outage. It can also help homeowners maximize their energy savings by drawing power from a battery bank during peak usage periods, which avoids high time-of-use (TOU) rates charged by the utility.
When the utility loses power, your solar system will remain on only in the event that it is equipped with battery backup. This means that your solar system will power your home during the day during an outage, and the battery will kick in at night. When the sun comes up, the battery will recharge, meaning that depending on how much energy you consume, your battery has the potential to power your home through any outage.