Start with what is on the wall
Take a photo of your solar inverter's label and your switchboard. Those two photos answer most compatibility questions. The ACCC lists compatibility with existing equipment as one of the first things to check when buying a battery.
The two ways a battery connects
A DC-coupled battery connects through a hybrid inverter that manages both the panels and the battery. If you already have a hybrid inverter, a matching battery may plug straight in. If not, it can mean replacing the inverter.
An AC-coupled battery has its own inverter and connects on the household side of the switchboard. It works alongside most existing solar inverters, which is why it is a common choice for retrofits. There is a small efficiency cost from converting power more than once.
Questions that decide the design
- Is the existing inverter a standard grid-tie or a hybrid model?
- How old is it, and is it still under warranty?
- Is the home single-phase or three-phase?
- Does the switchboard have room, or does it need an upgrade?
- Is there an export limit that the battery could help you work with?
Older systems
Many Sydney homes have solar installed ten or more years ago. Some of these systems are small, or the inverter is near the end of its life. In that case it can make sense to plan the battery and a solar refresh together rather than pairing a new battery with an inverter that may need replacing soon.
That is not always true. A healthy system with good capacity can pair well with an AC-coupled battery. The point is to decide with the facts in front of you.
Warranties
Adding equipment can affect existing warranties if it is not done in line with the manufacturer's requirements. Ask the installer to confirm in writing how the new battery affects the warranty on your current inverter and panels, and who you call if something goes wrong.
Backup is a separate decision
A battery does not automatically keep the lights on in a blackout. Backup needs compatible equipment and wiring. Read our backup explainer before assuming it is included.
Sources
Sources are linked for background reading. They do not endorse Green Home. This is general information, not advice for your home; a site assessment is needed for a recommendation.
