When you install solar power on your property, you will still be connected to the grid. You will use the grid as backup power source in the event of persistent overcast weather whereby your solar system generates less than you need. The grid connection also allows you the ability to sell your excess PV-generated power to your local electricity company. It is possible to go off the grid with a solar energy system that includes battery storage, but this is only recommended for properties that do not have access to the grid.