A battery increases self-consumption of solar generation and allows cheap night-rate charging, but it is not grant aided and payback depends heavily on your tariff and usage pattern. Model it against your actual consumption before committing.
The value of a battery comes from the gap between what you pay to import electricity and what you receive for export. Where the export tariff is reasonably high, storing surplus is worth less than it first appears.
Batteries suit households with high evening consumption, an electric vehicle, or a time-of-use tariff with a cheap night rate. They suit less well a household that is out all day with modest evening use.