Is a battery worth it yet, honestly?
Batteries have been about to make sense for years. The federal discount changed the sums. So here is the honest version. How a battery saves money, how to work out your own number, and the two homes where the answer is still no.
The short answer
A battery does not make power. It moves the solar power you would have exported, cheaply, into the evening when power is expensive. So the saving is the gap between what you get paid to export and what you pay to buy back. Multiply that gap by how much you shift each day. The federal discount takes roughly 30% off the price up front, which shortened the payback a lot. It works best in a house that uses a decent amount of power after dark. It still does not stack up in a small, low use household, or in one where the solar is already fully used during the day.
The number that matters
Look at your bill for the feed in rate you get paid and the rate you pay in the evening. The gap between them is what a battery earns.
Order matters
A battery is sized to the solar you do not use. If your hot water and heating are still gas, that number is about to change.
Ask for
Usable capacity, not nominal. The warranty in years and in cycles. And the price with the discount already taken off.
How a battery makes money
It is a gap, not a saving.
Solar makes most of its power in the middle of the day, when the house is often empty. That spare power goes out to the grid and you get paid a small amount for it. Then at six in the evening the sun is gone, everybody is home and the oven is on. You buy that power back at several times what you were paid for it.
A battery sits in the middle of that. It catches the power you would have exported and gives it back to you at night. It does not create anything. What it earns is the gap between the two prices, multiplied by how many units you can move through it each day.
So the sums come down to three things. How big the price gap is on your plan. How much spare solar you have. And how much power you use after dark. Not the size of the battery, and not the size of your roof.
The five minute version
Find your feed in rate and your evening usage rate on your bill. Subtract one from the other. Multiply by the number of units you think you could shift each day, then by 365. That is roughly what a battery saves you in a year, before you look at any price.
What is on the table
The help that is actually available.
The federal discount
There is one genuinely national program for batteries. It takes about 30% off the up front cost of a battery. Your installer puts it on the price, so there is nothing to claim back. It is the single biggest reason the arithmetic changed.
Why it comes here
Applies wherever you live in Australia. Nothing to claim, nothing to wait for.
Who does it
Any installer accredited to claim it. Ask to see the discount as its own line on the quote.
About 30% off
Australia wideA discount on installing a battery between 5 and 100 kWh, claimed on the first 50 kWh of usable capacity. The amount steps down every six months until 2030, so waiting a year costs you something real.
Your state, on top
Some states add their own help and some do not. Western Australia is the clearest example right now. The amount depends on who sells you your power, and there is a condition about joining a virtual power plant.
Why it comes here
State help stacks with the federal discount where it exists. It is also the part that changes most often.
Who does it
An installer who works in your state and knows this month’s rules.
$1,300 to $3,800
Western AustraliaSynergy customers get up to $1,300 and Horizon Power customers up to $3,800. The battery has to be able to join a virtual power plant, and the household has to join one. There is also a no interest loan for households under an income limit.
A loan instead of a rebate
In the ACT the help is money lent cheaply rather than money given. That suits a battery well, because the repayments and the bill savings can be arranged to land in roughly the same place each month.
Why it comes here
A low rate over a long term changes the monthly picture even when the total price does not move.
Who does it
Any accredited installer. The loan is arranged with the scheme, not the installer.
3% over 10 years
Australian Capital TerritoryBetween $2,000 and $20,000 at 3% over up to ten years, with no fees and no penalty for paying it out early. Batteries and EV charging are both on the eligible list.
Two homes where it is still no
Not everybody should buy one, and the sales pitch will not tell you that.
The first is the small, low use household. If you use a modest amount of power and most of it during the day, there is very little to shift. A battery in that house spends most of its life full and idle, and the saving never gets near the price. Two people who are out all day and cook simply are the classic case.
The second is the home whose solar is already fully used. Run a pool pump, a heat pump hot water system and a car charger in daylight, and you may already put almost nothing out to the grid. There is no gap left to arbitrage. That is a good problem, and it means your money is better spent elsewhere.
There is a third case worth naming even though it is not about money. Some people want a battery so the lights stay on in a blackout. That is a fair reason to buy one. Just check it explicitly, because not every battery keeps working in an outage, and the ones that do need extra wiring to do it.
What to ask an installer
Five questions that sort the quotes out.
Ask for usable capacity rather than nominal. A battery is sold on a headline number, and only part of it can be used. Two batteries with the same badge can be quite different sizes.
Ask for the warranty in years and in cycles, and which one runs out first for you. A ten year warranty that is really a cycle count you will hit in six is not a ten year warranty.
Ask whether it keeps working in a blackout, and what that costs to set up. Ask what a virtual power plant means for you. Is it required by the rebate you are taking? And how do you leave it?
And ask for the price with every discount already taken off, next to the price before them. Not because anybody is hiding anything, but because it is the only way to compare two quotes that claim different rebates.
What we couldn’t confirm
The battery numbers we would not print.
This is the upgrade with the most confident arithmetic attached to it and the least of it traceable. Here is what we left out.
“Batteries pay for themselves in seven years”
The payback depends on your rates, your spare solar and your evening use. Those three vary more between houses than anything else on this site. Do the five minute sum above with your own bill.
A state top up in every state
Some states run one, some do not, and the rules change. We only print the ones we have checked, with the date on them.
“Go off grid and stop paying bills”
Leaving the grid entirely needs far more battery and usually a generator, and it costs many times what a normal home battery does. It is a different project, not a bigger version of this one.
Quick answers
The questions people ask next.
Do I need solar before a battery?
Practically, yes. Without solar a battery can only shift cheap grid power into expensive hours, which is a much smaller gap and only works on certain plans. Almost everybody buying one already has panels.
How big should it be?
Sized to how much spare solar you have and how much you use after dark, not to your roof. If your hot water or heating is about to go electric, tell the installer, because it changes both numbers.
What is a virtual power plant?
An arrangement where your battery can be used by an operator at busy times, in exchange for payments or a rebate. Some schemes require it. Read the exit terms before you sign, because it is your battery being used.
How long do they last?
Most are warranted around ten years or a set number of cycles. They do not stop dead, they slowly hold less. Ask what capacity the warranty guarantees at the end of the term, because that is the real number.
Is it safe indoors?
Home batteries sold in Australia have rules about where they can be installed, and a garage or an external wall is the usual answer. Your installer works to those rules. Ask where yours is going and why, before the day.
Should I wait for prices to fall?
Prices have been falling and the federal discount is stepping down every six months, so the two partly cancel out. If the sum works on today’s numbers, waiting mostly costs you a year of savings.
What to do this week
Get your own number before anybody quotes.
Tonight
Find your last bill. Write down the feed in rate you are paid and the rate you pay in the evening.
This week
Look at your solar app for how much you exported last month. That is the pool a battery has to work with.
Before quoting
Decide whether your hot water and heating are staying on gas. If they are not, say so, because it changes the right size.
When you’re ready for help
Find the right help for your next step.
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