In our area (the bay area), you can't have battery storage and have a grid connection. So in the setup you describe when the power goes out we couldn't run our house on solar energy. We would have to wait for the grid to come back up. It's crazy. That means batteries would be necessary. But we don't have a battery room or room for one. So this is the perfect solution. Will it save money? Tier 4 pricing with PG&E is 34 cents per kwh and the rates are going up. In the summer it's quite easy to hit tier 4.