What Size Solar Battery Do I Actually Need? An Australian Homeowner’s Guide
10kWh? 13.5kWh? 20kWh?
If you’re asking “what size solar battery do I need?”, here’s the good news:
You don’t need to become an energy expert to figure it out. But you do need to look beyond the size of your house.
Start with one question: when do you use electricity?
Two similar Queensland homes can have very different energy needs.
A pool, air conditioning, an EV or simply spending more time at home can significantly change how much electricity you use – and when you use it. Queensland household benchmarks also vary considerably by household size and season.
If most of your electricity is used while your solar panels are producing, you may need less battery storage. If your home comes alive after sunset, more home battery capacity could make sense.
The timing matters just as much as the total.
Is a 10kWh battery enough?
For some households, a 10kWh battery can cover a significant portion of evening and overnight electricity use.
But don’t choose 10kWh simply because it sounds like a nice round number.
Your ideal battery size for a house depends on how much energy you actually want to shift from daytime solar into the evening.
Your solar fills the battery. Your lifestyle empties it.
The goal is to balance the two.
When could a 20kWh battery make sense?
A 20kWh battery may be worth considering if your home has higher energy demands – think EV charging, a swimming pool, heavy air-conditioning use, an all-electric home or greater backup expectations.
But bigger isn’t automatically better.
There’s little value in paying for storage capacity your solar can’t regularly fill – or your home rarely uses.
Want blackout backup? That changes the equation.
If backup matters, battery capacity isn’t the only number to consider.
You also need to think about power output and what you actually want running during an outage. Keeping the fridge, lights and Wi-Fi going is very different from powering air conditioning, cooking appliances and much of the home.
The system needs to be designed around that expectation.
So, what’s the right solar battery size?
Forget the one-size-fits-all answer.
Your electricity consumption, excess solar, evening usage, EV, pool, air conditioning and backup expectations all matter.
A solar battery size calculator can be a useful starting point. But smart meters can provide something far more valuable: real data showing both how much electricity your home uses and when it uses it.
At Weglow, we look at how your home actually uses energy before recommending a battery.
Because the goal isn’t to fit the biggest battery on your wall. It’s to fit the right one into your life.