Backup power gateway

Written and checked by the Energy Merchants desk · Reviewed 3 October 2026

A backup power gateway is the device that lets a home keep running when the grid fails. It detects the outage, opens a switch to separate the house from the network, and tells the battery and inverter to supply the home. When the grid comes back, it checks the supply is stable and reconnects.

The isolation is not optional. Without it, a battery feeding the house could also push power into the street, a danger to line crews. This is the reason that anti-islanding rules exist in AS/NZS 4777.2.

Two backup designs

• Essential loads. Selected circuits, such as lights, fridge and internet, are rewired to a protected board. The battery needs to cover only those. It is simpler and cheaper.
• Whole home. The gateway isolates the entire switchboard. It needs bigger inverter capacity, and large loads such as ovens or ducted air conditioning may still be excluded or managed.

In practice

Many batteries ship without backup capability enabled, or it is an add-on. Check this when you quote, because customers often assume a battery means blackout cover. A typical battery that charges and discharges for tariff savings may switch off in an outage unless a gateway and a backup-capable inverter are installed.

Backup capacity is a design question: how many kW can the system sustain, and for how long? A 10 kWh battery feeding a 1 kW essential load could last most of a day with some solar. The same battery on a 5 kW demand will empty in two hours.

Installers must follow AS/NZS 5139, and photos should show the gateway and its labelling. The battery submission guide lists the evidence.

Common confusion

A gateway is not the battery and not the inverter. It is also unrelated to a smart meter or a communications gateway used for VPP signals, though some products blend functions. For a home with no grid connection at all, see SPS.

For claims, see battery STCs. More terms are in the glossary.