It's one of the most common questions we get — and one of the most misunderstood. The short answer: yes, a home battery can keep your house running through a blackout, but only if the system is specifically set up to do it. Plenty of battery systems don't back up your home at all by default. Here's why, and what to look for.
Why not every battery keeps the lights on
This one surprises people: a standard solar-and-battery system, the moment the grid goes down, will usually shut off completely — battery included. It isn't a fault. Grid-connected inverters are required by Australian standards to disconnect during an outage, a safety feature called anti-islanding. It stops your system feeding power back into the network while line workers are repairing it. Without it, you'd be putting them at risk.
The catch is that a basic grid-tied setup can't tell the difference between "the grid is down" and "shut everything off." So to keep running through a blackout, your system needs extra hardware — a backup gateway (an automatic transfer switch) and a backup-capable inverter — that safely isolates you from the grid and runs your home as its own island. This has to be designed in. It isn't something you can switch on later without the right equipment.
What backup actually looks like
With a backup-ready system, the moment the grid drops, the gateway disconnects your home from the network and your battery takes over — automatically, usually within a second or two. Most of the time you'll barely notice beyond a brief flicker. When grid power returns, it switches back just as automatically. You don't have to do a thing.
Whole home, or just the essentials?
You have two broad options, and they're a real trade-off:
- Essential-circuit backup — a dedicated backup circuit powers the things that matter most: lights, the fridge and freezer, internet and phones, and a few power points. It's the more economical option and covers what most households actually need in an outage.
- Whole-home backup — everything keeps running, including larger loads. This needs more battery capacity and a bigger inverter to handle peak demand (think air conditioning kicking in), so it costs more — but nothing in the house knows the grid is gone.
Which one's right comes down to what you want protected and your budget. We talk it through during the site assessment rather than guessing.
How long will it last?
That depends on two things: how much energy your battery is holding, and how much your home is drawing. Backing up a few essential circuits stretches much further than running the whole house with the air conditioner on. As a rule of thumb, the lighter the load you're backing up, the longer you'll ride out the outage.
There's a useful bonus if your system supports it: in a daytime outage, your solar panels can keep generating and recharge the battery while it powers the home — effectively extending your runtime for as long as the sun is up. Not every configuration allows solar to run during an outage, so if multi-day resilience matters to you, flag it early and we'll design for it.
What you can and can't run
Small and essential loads — lighting, refrigeration, devices, routers, medical equipment — are no problem on a properly sized backup system. Big motor-driven loads like ducted air conditioning, pool pumps, or instantaneous hot water draw a lot of power at once, so whether they'll run on backup depends on your inverter's output and how much battery you have. None of this is guesswork — it's a sizing exercise, and it's exactly what we work out with you before quoting.
The key thing: decide on backup up front
Because blackout protection depends on the right hardware being installed, the single most important step is telling your installer it matters to you before the system is designed. Retrofitting backup onto a system that wasn't built for it is far more expensive than including it from the start. Our Dyness systems support blackout protection, and if it's a priority for you, we build it in — sized around the circuits and runtime you actually want.
Learn more about our home battery systems, or get a free quote and tell us backup matters — we'll design it in. You can also call Rhys directly on 0428 660 510.