Most solar energy systems, whether they include a battery or not, are connected to the grid. This connection allows solar panel owners to “sell” excess power produced by their systems back to the grid for credits on their future energy bills. During a power failure, a grid-connected solar system with no battery will shut down. This is a safety feature so utility electricians can fix issues without the risk of unexpected energy from solar hitting the powerlines. With Solar + Battery, the solar panels and battery can work together independently during a power outage and keep your lights on, regardless of whether the grid is online.