If you own a solar system and want to add batteries then, in theory, the cheapest way to do this is to simply plug your batteries into your existing solar inverter. The solar inverter can then convert the batteries’ DC power into AC power, just like it does for your solar.
Unfortunately, in practice, regular solar inverters are not designed to be shared by solar and batteries, so this hasn’t been possible and battery upgrades have been jolly expensive as a result.
But Goodwe, a major Chinese inverter manufacturer, has just released a battery DC converter, going by the catchy name of GW2500-BP. It is designed to allow batteries to interface to existing solar inverters.
This DC converter may be the cheapest way to add batteries to an existing solar home. It will also bypass any restrictions that Australian network operators may put in the way of using battery-inverters, such as the Sunny Boy Storage.