Begin with what is already installed
Record the solar inverter model, panel array, supply phase, installation date and available connection documents. These determine which retrofit options deserve investigation. A battery installation assessment should also consider where equipment can be safely located, how it will be monitored and what the battery is intended to do.
The existing inverter does not automatically need replacing. Australian Government guidance describes AC coupling as a usual arrangement for adding a battery to existing solar. That is a starting point, not approval for any combination of products. Exact models, firmware and system configuration still need written confirmation.
Compare the electrical architectures
| Approach | What changes | What to verify |
|---|---|---|
| AC-coupled battery | A battery inverter connects on the AC side alongside existing solar | System control, metering, connection limits and outage interaction |
| DC-coupled battery with a suitable hybrid inverter | Solar and battery connect through a compatible hybrid arrangement | Approved battery pairing, existing array compatibility and any inverter replacement |
| Broader redesign | Some existing equipment is changed as part of the project | Why changes are necessary and what is retained or removed |
Battery-ready is not a compatibility certificate
An old sales description may omit required interfaces, supported battery generations or activation conditions. Ask for current manufacturer documentation naming the proposed combination. A common brand name is insufficient: products from the same manufacturer can have different communication protocols, voltage ranges or permitted configurations. This guide deliberately provides no universal compatibility matrix.
Separate everyday operation from blackout operation
A retrofit that stores daytime energy may still lack backup. During an outage, a grid-connected solar inverter normally stops unless the complete system is designed to support an islanded arrangement. Ask whether solar can recharge the battery when the grid is absent, which circuits or phases remain supplied and what happens if the battery is depleted.
Use the essential-loads backup guide to define the outage goal. Use capacity versus power to avoid choosing solely by stored kWh. An inverter’s power limit can matter even when substantial energy remains in the battery.
Include site and approval work in the comparison
- Existing system condition and documentation quality.
- Permitted battery location and necessary access or protection work.
- Switchboard, supply and metering assessment by qualified people.
- Network approval or connection changes and who coordinates them.
- Monitoring ownership, configuration and commissioning records.
- Separate product and installation warranties, including retained equipment.
Compare complete scopes rather than equipment-only quotes. AC coupling may preserve a working inverter; a hybrid redesign may make sense where other changes are already needed. Neither option is automatically best without site conditions and future plans. Ask the designer to explain the trade-off and identify any assumptions that remain unverified.
Plan for ownership after installation
Keep manuals, settings, backup instructions and support contacts together using the handover checklist. If later capacity growth is important, read expanding an existing home battery now, but do not assume future modules will remain compatible or available. The combined solar and battery service is the wider planning route for a coordinated redesign.
Sources and scope
Source check: 5 October 2026. General educational information, not an electrical design or a site assessment. Product instructions, local rules and contract terms must be checked for your circumstances.
- Australian Government — Batteries
Usable capacity versus power; AC/DC coupling; backup requires configuration; site restrictions; warranty and management questions.
Scope: Australia. Source date: Includes program information commencing 1 July 2025; page date not displayed.
- Australian Government — Inverters
String, optimiser and microinverter architecture; shade limitations; battery/hybrid inverter roles and phase-dependent backup.
Scope: Australia. Source date: No publication date displayed.
- Australian Government — Design considerations
Roof direction, slope, shade, condition, future loads, network limits and expansion constraints.
Scope: Australia; local network and planning rules vary. Source date: No publication date displayed.
Discuss your project or system
Share your goals and the information you have collected. Ask what assessment is appropriate for your circumstances.