My future house, I want to be off the grid, sort of. It will be a house on a lake, and I know there is more of a risk of power outage in that location. So, what I am thinking is a system that has solar panels and wind turbines. This is fed to a battery bank. The house is still connected to the grid, but when the power goes out, the batteries keep me in power. When the batteries are fully charged, the excess power can be sent to the grid. Does that setup exist?