This will depend on your lifestyle, energy usage and size of PV system.
On average, a household would utilise 35 – 50% of the generated system without a battery. This would rise if you were in the house for much of the day. However, battery storage can raise this to 80%. If you have a system already installed and use all the energy generated from your PV system, then battery storage may not be right for you. However, if there is spare generation, then it could be a great way to further reduce your energy bill.
It is always recommended to look at your inverter monitoring to see how much of the power generated is being consumed during the day, before deciding if battery storage is right for you.