How should the battery connect?
AC coupling, a hybrid inverter, an integrated stack and a compatibility-led battery platform solve different retrofit and new-system problems.
Which battery architecture fits your house?
A 30 kWh battery is not one type of system. Existing solar, inverter condition, single- or three-phase supply and the backup you expect can change which battery architecture makes sense. Use the four-question chooser first, then inspect the relevant manufacturer guides.
BATTERY ARCHITECTURE CHOOSER
Start with the house. Then narrow the battery systems.
These four answers do not choose a brand for you. They narrow which system architectures deserve the first comparison.
YOUR RESULT
Choose the closest answer above.
You can use “Not sure” anywhere. The tool is designed to narrow the conversation, not force certainty you do not have yet.
Educational comparison only. The final architecture depends on the exact inverter, battery, switchboard, phase arrangement, network approval, installation design and current Australian product documentation.
The result narrows the first conversation. It does not choose the product.
kWh and kW are separate
Battery capacity tells you how much energy can be stored. Inverter and battery power tell you how quickly it can charge, discharge and support loads.
Backup is an electrical design
A battery does not automatically mean the whole home operates in a blackout. The inverter, gateway, switching, phases and protected circuits determine the result.
Then compare products
Once the architecture is sensible, compare usable kWh, continuous power, compatible equipment, expansion rules, warranty and Australian support.
The battery badge matters less than the way the system is built.
| Path | Usually worth comparing when | Main question | Examples |
|---|---|---|---|
| AC-coupled retrofit | Existing solar is working well and you want to preserve its inverter | How does the separate battery inverter handle charging and backup? | FranklinWH, sonnen, Enphase, Anker SOLIX |
| Hybrid inverter + DC battery | New solar and battery together, or an old inverter is already being replaced | Which exact battery family is compatible with the hybrid inverter? | GoodWe, Sungrow, SolaX, Growatt |
| Integrated modular system | New/replacement system, larger storage or coordinated backup and energy management | What inverter/controller, battery modules and gateway are actually in the stack? | Sigenergy, EcoFlow, Hinen, SAJ |
| Compatibility-led battery platform | You want battery and inverter choices kept distinct, or already have a supported hybrid inverter | Is the exact battery/inverter/firmware combination on the current compatibility pathway? | BYD Battery-Box, Pylontech, PowerPlus Energy, Fronius ecosystem |
This is deliberately not a quality ranking. Two architectures can both be technically sound while producing very different retrofit cost, expansion options, monitoring and blackout behaviour.
“I want about 30 kWh” is a useful starting point, not a finished specification.
A household comparing roughly 25–35 kWh of storage should ask at least four extra questions: how much of that capacity is usable, how many kilowatts the system can charge and discharge continuously, how much energy is realistically available to refill it on an ordinary day, and whether the desired backup loads fit inside the inverter's output.
For example, adding more battery modules can increase stored energy without increasing inverter power by the same amount. A larger battery can therefore run the same load for longer while still having the same maximum instantaneous output. This distinction matters for ducted heating/cooling, induction cooking, pumps, EV charging and broad blackout backup.
Expansion rules matter too. Some systems are designed around modular stacks, while others require particular battery generations, firmware, controller ratings or installation timing when extra modules are added later. If future expansion is part of the reason for choosing a product, have that pathway written into the proposal rather than relying on a generic “expandable” label.
Use the solar and battery calculator to estimate a sensible storage range →
A good existing inverter changes the battery decision.
If the current solar inverter is serviceable, correctly sized and not otherwise due for replacement, AC coupling deserves a serious comparison because storage can potentially be added beside it. Replacing the inverter with a hybrid model may still be worthwhile when the old equipment is ageing, the array is being upgraded, or the desired backup design needs a different architecture.
The important point is to separate “I need a battery” from “I need to replace my solar inverter”. They are not automatically the same decision. Ask the installer to identify the current inverter model and age, then show why the proposed architecture preserves or replaces it.
Three-phase supply and battery backup are related, but they are not the same question.
A three-phase house does not automatically require the largest three-phase battery system, and it does not automatically receive three-phase backup. Some designs place storage on one phase, some use three-phase hybrid equipment, and some provide different behaviour in grid-connected operation versus an outage.
That is why “whole-home backup” needs more detail. A useful quote states which circuits or phases remain powered, continuous backup kW, short-duration surge capability where relevant, the switching/gateway equipment included, and any major loads that are deliberately excluded. Battery kWh then determines roughly how long those supported loads can operate.
Turn the architecture into an exact equipment schedule.
- Exact inverter/controller model, AC rating and single- or three-phase arrangement.
- Exact battery model, module quantity, nominal capacity and usable capacity.
- Continuous charge and discharge power in kW, plus any relevant peak/surge limits.
- Whether a gateway, backup switch, smart meter or communications device is required and included.
- Which circuits and phases operate during a blackout, and which major loads are excluded.
- Current Australian inverter/battery compatibility documentation for the exact model combination.
- Expansion limits and any restrictions on adding modules later.
- Current Australian warranty terms for the inverter, battery and supporting equipment.
- Network approval implications if an existing solar inverter is replaced or the connection arrangement changes.
Battery comparison FAQ
Is AC coupling worse than DC coupling?
No. They solve different problems. AC coupling can be especially useful when preserving an existing solar inverter. A hybrid/DC design can be cleaner when solar and storage are being installed together. Compare the complete system rather than treating one coupling method as universally superior.
Does a 30 kWh battery provide 30 kW of power?
No. kWh measures stored energy; kW measures power. A 30 kWh battery may have an inverter capable of materially less than 30 kW. The exact continuous and backup power ratings belong on the quote.
Does three-phase power mean I need a three-phase battery?
Not automatically. The right arrangement depends on the existing solar, load distribution, desired backup behaviour, network conditions and the supported system architecture. Ask the installer to explain the phase arrangement explicitly.
Should I choose the brand before the architecture?
Usually no. Work out whether the project is a retrofit, new hybrid system, integrated platform or compatibility-led design first. Then compare the exact brands and models that can execute that architecture well for the property.