Three-phase design · Brisbane technical guide
Does a three-phase home need a three-phase battery?
Sometimes—but the supply label is only the first input. Existing solar, inverter capacity, whole-site metering, grid connection and the loads wanted during a blackout determine the useful architecture.
The short answer
Three-phase supply does not decide the battery by itself.
A property can have three-phase grid supply and still have existing solar connected through a single-phase inverter. A proposed battery may be AC coupled to that system, use a new single-phase hybrid inverter under an accepted connection pathway, or move to a three-phase hybrid architecture. Those are different designs—not interchangeable product labels.
The decision must account for the full distributed-energy system recorded at the property, how power is measured across the phases and what the network will approve. Energex’s current connection options also distinguish fixed and dynamic export arrangements, so “three phase” should not be used as a shortcut for assuming one inverter size or export outcome.
Architecture choices
Two common paths, with different consequences.
Single-phase battery pathway on a three-phase site
This can be conditionally workable when the supported inverter, site metering and network connection allow it. The design must show which phase the inverter serves, how whole-site import and export are measured, how existing solar is handled and what remains powered during an outage.
Confirm: existing DER, phase allocation, total inverter capacity, CT or meter arrangement, export control and backup circuits.
Three-phase hybrid battery pathway
This can suit homes where a three-phase inverter architecture better matches the solar design, larger loads or the intended backup scope. It is not automatically better: the battery compatibility, inverter model, network pathway and usable backup power still need to fit the property.
Confirm: complete AU inverter model, supported battery stack, PV strings, per-phase behaviour, switchboard work and EPS design.
Six design checks
Make the proposal explain the energy path.
1 · Existing DER
List every solar and battery inverter already connected, including complete models and their phase. A new battery is assessed as part of the combined site.
2 · Metering across phases
The control system needs a supported way to see site import and export. An incomplete CT or meter design can undermine charging and export control.
3 · Capacity versus output
kWh indicates stored energy; kW indicates power. Large air-conditioning, pumps, cooking and EV charging require an output and phase check, not just more modules.
4 · Backup boundary
Ask whether backup is selected circuits, a single phase or a supported three-phase scope. Confirm continuous power, peak limits, switching and excluded loads.
5 · Network pathway
Existing and proposed inverter capacity, export mode and site details determine the Energex application. A sales quote cannot guarantee approval in advance.
6 · Installation conditions
Switchboard space, neutral and protection arrangement, battery location, cable route and current manufacturer instructions remain site-specific.
Have a three-phase bill or switchboard?
Send the suburb, bill, existing inverter label and the loads you want during an outage. We’ll identify the likely architecture and the evidence still needed.
Three-phase questions
Separate the supply, system and backup decisions.
Does a three-phase Brisbane home need a three-phase battery inverter?
Not automatically. A three-phase supply can sometimes use a single-phase battery pathway, while other homes need a three-phase hybrid design. Existing solar, inverter capacity, metering, network connection, phase balance and backup loads must be assessed together.
Will a three-phase battery back up every phase during a blackout?
Only if the selected equipment and switchboard design explicitly support the required three-phase backup scope. Some designs back up selected circuits or one phase. The written proposal should identify the circuits and continuous and peak power limits.
Can I keep my existing single-phase solar inverter?
Possibly. An AC-coupled battery may allow the existing inverter to remain, while a DC-coupled hybrid design may change the inverter and PV arrangement. Compatibility, metering, outage behaviour and the current network application still need confirmation.
Is a larger battery enough for three-phase air conditioning or EV charging?
No. Battery kWh describes stored energy. Large loads also require sufficient inverter and battery power, correct phase architecture, suitable backup design and allowance for starting or sustained demand.
Related decisions
Continue with sizing, backup and existing solar.
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