Your outage reserve is the amount of battery power set aside for blackouts, and nothing can touch it until the grid goes down. Not SmartShift, not manual commands. If it ever runs low, your battery tops it back up from the grid.
So the question is: how much is enough to feel safe, without holding back battery you could be putting to work?
For most homes, we suggest about 2 kWh. Here's why, and how to adjust it for your household.
What your essentials actually use
When the power's out, you're not running the whole house. You're keeping a few key things going: the fridge, the internet, some lights, maybe charging phones.
These use far less than most people expect. Here's a typical Australian home, and what each essential draws over a 4-hour outage.
| Essential | Typical power | Energy over 4 hours |
|---|---|---|
| Fridge-freezer (cycles on and off, so averaged) | ~40 to 150 W | ~0.3 to 0.6 kWh |
| Wifi modem and router | ~10 to 20 W | ~0.05 kWh |
| A few LED lights | ~30 to 60 W | ~0.2 kWh |
| Phone and laptop charging | ~30 to 60 W | ~0.2 kWh |
| TV | ~50 to 150 W | ~0.3 kWh |
| Essentials total | ~0.5 kWh per hour | ~1 to 1.5 kWh |
A 2 kWh reserve covers all of that for 4 hours or more. If you're just keeping the fridge and wifi on, it stretches much further.
A note on fridges. A fridge's compressor switches on and off, so while it might be labelled 150 to 300 watts, it only draws that when the motor's running. Averaged over an hour it's much lower. That's why a fridge is cheaper to run in a blackout than it looks.
Further reading: energy.gov.au: estimate appliance running costs · Energy Rating Calculator: check your own appliances
How long do outages usually last?
The Australian Energy Regulator tracks how long the average customer is without power.
| Where you are | Typical outage length | How often |
|---|---|---|
| Metro (e.g. Sydney, Melbourne) | Around 1 to 1.5 hours | Roughly once a year |
| Regional and rural | Often 2 to 4+ hours | More often, and longer after storms |
A 2 kWh reserve keeps your essentials running for well over 4 hours, which covers the great majority of outages, in the city and most regional ones too.
What sets rural and remote homes apart is that outages there run longer and happen more often, and a big storm can knock power out for many hours or even days. If that's you, it's worth setting more.
Even with no power at all, a closed fridge keeps food safe for about 4 hours, and a full freezer for 24 to 48 hours. So between your reserve running the fridge and the fridge's own cushion, your food is well covered through a typical outage.
Sources: AER: network performance reporting · AER Electricity network performance report · NSW Food Authority guidance, via Ausgrid · SA Health: power failures and food safety
When to set more
The 2 kWh suggestion suits a typical suburban home. Set it higher if any of these sound like you.
| If you... | Why | Suggested move |
|---|---|---|
| Live rural, remote, or at the end of a long line | Country outages are more frequent and much longer, sometimes hours while crews travel | Set a bigger reserve |
| Are in storm, cyclone or bushfire country | Severe weather causes the multi-day outages people remember | Size up, especially in storm season |
| Rely on medical equipment (CPAP, oxygen, medication fridge) | Losing power isn't an inconvenience, it's a risk | Set generously, and register as a life-support customer |
| Want more than the essentials on | Aircon, electric hot water, oven or EV charging climb fast (see below) | Match your reserve to what you want running |
What "more than essentials" costs you. These loads are in a different league to the fridge and wifi:
| Appliance | Typical power | Energy over 4 hours |
|---|---|---|
| Air conditioner | ~1,000 to 2,000 W | ~4 to 8 kWh |
| Electric hot water | ~1,500 to 3,600 W | ~6 kWh+ |
| Oven or cooktop | ~1,000 to 2,400 W | ~4 kWh+ |
| Kettle (occasional) | ~1,800 to 2,400 W | high, in short bursts |
| EV charging | ~2,000 to 7,000 W | ~8 kWh+ |
One of these can use more in an hour than all your essentials use in a day. If you want them covered, you'll need a much larger reserve.
Further reading: AER: network performance reporting (rural vs urban reliability) · Ausgrid: life support registration · energy.gov.au: heating, cooling and appliances
Two things worth knowing
Backup usually covers only part of your home. Most systems are wired to keep selected circuits on in an outage, not the whole house. So your "essentials" may already be set by how yours was installed. Not sure what stays on? Your installer can tell you. (What to ask your battery installer, SolarQuotes)
More reserve means less earning. Every bit you hold back is battery that isn't saving or earning the rest of the time. The right setting is the smallest reserve that still lets you sleep easy.
You can change your reserve any time, so start with our recommendation and adjust once you get a feel for how often your power actually goes out.
Energy figures are typical estimates and your appliances may vary. Outage statistics are based on Australian distribution network reporting to the Australian Energy Regulator. Food-safety timing follows Australian food authority guidance. This is general guidance, not medical advice. If someone in your home depends on medical equipment, speak to your equipment provider and register as a life-support customer.
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