If you are on the grid you use the grid as your battery sending excess power when you have it, and drawing from the grid when you need more power than your panels generate.
If you are off the grid you obviously need batteries, but would only be eligible if you were moving from a diesel generating system.
I don't expect they are contemplating people who are grid connected also having batteries. There is no benefit to that under normal conditions (batteries would only be useful if grid power went down). But unfortunately there isn't much info available so we can't know for sure.