Domestic and commercial battery storage have been designed to be used in two different ways:
Batteries can store excess electricity generated from your Solar PV installation during daylight hours in order to be used out of day light hours. This ensures that when night-time arrives and your solar panel system is no longer generating electricity, you are able to use the excess electricity that has been stored in your battery to power your property in the evening or overnight.
Cheap electricity tariffs:
Another way that solar batteries can be used is to be charged through a cheap Economy 7 style tariff. This means that your battery charges overnight when electricity is cheaper and is then used during the day when it is more expensive therefore reducing the amount of electricity bought at peak times.