Battery backup for power outages
Standard solar switches off when the grid goes down. A battery can keep your essentials running, but only if the system is designed for backup. Here's how it works.
Updated November 2026 · Litmec Electrical, REC-10383
Ordinary grid-connected solar shuts down in a blackout, by design, so it can't send power into lines that crews are working on. That's true even on a sunny day.
A battery with a backup-capable inverter and the right switchboard wiring keeps chosen circuits running during an outage, and the panels recharge it in daylight. A 10 to 15 kWh battery typically runs a fridge, freezer, lights, internet and a water pump through a night with room to spare.
Why solar alone goes off in a blackout
Grid-connected inverters must stop exporting within a fraction of a second when the grid fails (anti-islanding, required by AS/NZS 4777). Without a battery and backup function, the panels can't power the house on their own.
What backup needs
- A backup-capable inverter or gateway that disconnects the house from the grid and runs it as an island.
- A backup circuit: most systems back up chosen essential circuits; some can run the whole house. Whole-house backup needs a bigger inverter and is limited by what the battery can supply at once.
- Switchboard work to separate the backed-up circuits. That's work for an electrician, and it's ours.
What a battery can run
| Load | Typical use per day |
|---|---|
| Fridge | 1 to 2 kWh |
| Chest freezer | 0.5 to 1.5 kWh |
| LED lights, internet, phone charging | 0.5 to 1.5 kWh |
| Pressure or bore pump | 0.5 to 3 kWh, depending on use |
| Reverse-cycle split system, a few hours | 2 to 6 kWh |
Essentials alone are usually 3 to 8 kWh a day. With panels recharging the battery in daylight, a 10 to 15 kWh battery can ride through multi-day outages in most seasons. Electric hot water, ovens and ducted heating are usually left off the backup circuit.
Why it matters in country Victoria
In February 2024 storms cut power to hundreds of thousands of Victorian homes, and some rural properties waited more than a week for supply to return. Properties at the end of long lines, in storm or bushfire country, and households with medical equipment or livestock water on pumps get the most value from backup.
Backup vs going off-grid
Going fully off-grid needs a much larger battery and panel array, plus a generator for long cloudy spells, and usually only pays where a new grid connection would be very expensive. For a property already connected, grid-connected solar with battery backup gives most of the resilience at a fraction of the cost.
Generators
A generator must connect through a proper inlet and changeover switch installed by an electrician, never by back-feeding a power point. Some battery systems can also take a generator input to recharge in long outages.
Related
Size solar and a backup battery for your home
Pick a battery in step 3 and tell us in the notes what you need kept running in an outage.
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Questions
Does solar work during a power outage?
Not on its own. Grid-connected solar shuts down when the grid fails, for safety. You need a battery with a backup-capable inverter and backup wiring to keep power on.
How big a battery do I need for backup?
Essentials (fridge, freezer, lights, internet, a pump) are usually 3 to 8 kWh a day, so a 10 to 15 kWh battery recharged by solar covers most outages. We size it from what you want kept running.
Can a battery run my whole house in a blackout?
Some systems can, but whole-house backup is limited by how much power the inverter and battery can deliver at once. Most homes back up essential circuits only, which makes the battery last longer.
Is it worth going off-grid in country Victoria?
Usually not if you're already connected. Off-grid needs a much bigger system and a generator. Grid-connected solar with battery backup gives most of the resilience for far less.
Check it on your roof
One minute online, then a free visit from a licensed electrician who checks your roof and switchboard.