Energy security – if battery is charged during a power outage, internal strata electricity can run for a period during a grid power outage.
Allows a larger solar system to be installed, getting economies of scale on solar installation.
Allows excess solar to be stored during the day, to be used at night (after solar generation ceases).
Ability to charge battery at off-peak rates and provide electricity during peak rate periods, saving money.
Ability to allow a third party to operate the battery for Demand Response for grid stabilisation.