What a battery saves: the gap between your usage rate and your feed-in
A battery earns the difference between what exported power is worth (the feed-in tariff) and what evening power costs (the usage rate), on every kilowatt-hour it moves between the two. A 10 kWh battery cycled once a day at 90 per cent usable depth moves 3,285 kWh a year. In South Australia that gap is 37c and the battery saves $1,215 a year; in Northern Territory, where the feed-in is 9.13c, the gap is 19.87c and the saving $653. The table prices the typical 10 kWh install of $9,500 to $12,500 after the $2,652 federal discount.
| State | Usage rate | Feed-in | Gap | Saving a year | Payback |
|---|---|---|---|---|---|
| New South Wales | 34c | 4c | 30c | $986 | 6.9 to 10.0 years |
| Victoria | 29c | 3c | 26c | $854 | 8.0 to 11.5 years |
| Queensland | 30c | 5c | 25c | $821 | 8.3 to 12.0 years |
| South Australia | 40c | 3c | 37c | $1,215 | 5.6 to 8.1 years |
| Western Australia | 33c | 2.75c | 30.25c | $994 | 6.9 to 9.9 years |
| Tasmania | 30c | 9.28c | 20.72c | $681 | 10.1 to 14.5 years |
| ACT | 27c | 6c | 21c | $690 | 9.9 to 14.3 years |
| Northern Territory | 29c | 9.13c | 19.87c | $653 | 10.5 to 15.1 years |
The model is deliberately plain: one full cycle a day, no income from a virtual power plant, no tariff rises and no capacity loss, so it understates a battery on a time-of-use plan with a steep evening peak and overstates one that sits half-charged through winter. Payback inside the 10-year warranty that every brand on the battery guide carries is the test.
13.5 kWh: $8,451 to $11,451 after discount
The 13.5 kWh class (Tesla Powerwall 3 and the larger Sungrow and BYD stacks) installs for $12,000 to $15,000 before the discount and earns $3,549 at 6.8 certificates per usable kWh, so $8,451 to $11,451. It moves 4,435 kWh a year on the same one-cycle assumption, which only pays if the household uses that much after dark; a home with solar and 6,000 kWh of annual use rarely does.
| State | Saving a year | Payback |
|---|---|---|
| New South Wales | $1,330 | 6.4 to 8.6 years |
| Victoria | $1,153 | 7.3 to 9.9 years |
| Queensland | $1,109 | 7.6 to 10.3 years |
| South Australia | $1,641 | 5.1 to 7.0 years |
| Western Australia | $1,342 | 6.3 to 8.5 years |
| Tasmania | $919 | 9.2 to 12.5 years |
| ACT | $931 | 9.1 to 12.3 years |
| Northern Territory | $881 | 9.6 to 13.0 years |
The federal discount falls on 1 January 2027
The Cheaper Home Batteries Program pays 6.8 certificates per usable kWh for batteries installed to 31 December 2026 and 5.7 from 1 January 2027, so the discount on 10 kWh drops from $2,652 to $2,223, a step of $429. The discount applies in full to the first 14 kWh, at 60 per cent from 14 to 28 kWh and 15 per cent above that, which is why 13.5 kWh earns $3,549 and a 20 kWh battery only $4,641. The January 2027 guide sets out the install-date rule for both the solar and battery discounts.
When a battery is worth it, and when it is not
Worth it: a usage rate above 30c with a feed-in under 5c (South Australia, New South Wales, Western Australia); a time-of-use plan with an evening peak the battery can cover; a household at home in the evening using 8 kWh or more after dark; a VPP payment on top; or a backup need where an outage costs money. Not yet: a feed-in near 9c (Tasmania, the Northern Territory), evening use under 5 kWh, a system under 6.6 kW that cannot fill the battery in winter, or a quote above $12,500 for 10 kWh before the discount. Price the solar first: the solar plus battery page has the bundle prices by capital, and the battery rebate calculator gives the discount for any size.
Battery questions
Is a solar battery worth it in Australia?
5.6 to 8.1 years is the payback on a 10 kWh battery in South Australia after the federal discount, inside a 10-year warranty, so yes there; in Northern Territory it is 10.5 to 15.1 years, so not on the numbers alone. The state table above gives every case.
How much does a 10 kWh solar battery cost after the rebate?
$6,848 to $9,848 installed in October 2026, from $9,500 to $12,500 before the $2,652 federal discount (68 certificates at $39).
How much does a solar battery save per year?
$653 to $1,215 a year for 10 kWh by state, from 3,285 kWh a year moved from export to evening use; $881 to $1,641 for 13.5 kWh.
What is the battery payback period in South Australia?
5.6 to 8.1 years for 10 kWh, the fastest in the country, because a 40c usage rate against a 3c feed-in makes each shifted kilowatt-hour worth 37c.
Is a battery worth it in Tasmania?
10.1 to 14.5 years for 10 kWh in Tasmania, the slowest of the states, because the 9.28c feed-in leaves only 20.72c to earn on each kilowatt-hour shifted; the Tasmania guide has the full figures.
How much is the battery rebate in 2026 and 2027?
$2,652 on a 10 kWh battery installed by 31 December 2026 and $2,223 from 1 January 2027, when the factor falls from 6.8 to 5.7 certificates per usable kWh; $3,549 on 13.5 kWh this year.
Is a 13.5 kWh battery worth it over 10 kWh?
$1,603 to $1,603 more after discount for 3.5 kWh more storage, which only pays if the household uses that extra storage every evening; the 13.5 kWh table shows the payback by state on a full cycle.