Calculate the battery discount
Use the usable capacity from the battery datasheet, not the nominal figure; the regulator counts usable kWh. The install window sets the STC factor, and the date that counts is the day the battery is installed and signed off, not the day you order. Nothing you enter leaves your browser.
How the discount is made
The Cheaper Home Batteries Program pays through the same certificates as rooftop solar. For a battery installed between 1 May and 31 December 2026 the regulator issues 6.8 STCs per eligible kWh of usable capacity. Eligible capacity is tiered: every kWh up to 14 counts in full, every kWh between 14 and 28 counts at 60 per cent, every kWh between 28 and 50 counts at 15 per cent, and capacity above 50 kWh counts for nothing. Multiply eligible kWh by the factor, round down to a whole certificate, and multiply by the price the installer gets for each one, assumed on this site to be $39.
At that price the first 14 kWh are worth $265 per kWh, the next 14 are worth $159 per kWh and the 22 above that are worth $40 per kWh. The factor steps down to 5.7 on 1 January 2027 and then every six months until the program ends in 2030. One battery per premises is eligible, it must be new, on the Clean Energy Council approved list, at least 5 kWh usable, installed by an accredited installer with battery endorsement, and connected to a VPP-capable inverter.
Worked examples in full
A 10 kWh battery installed in November 2026 is inside the first tier, so all 10 kWh are eligible: 10 x 6.8 = 68, rounded down to 68 certificates, worth $2,652 at $39. A 13.5 kWh battery, the usable size of several popular units, earns 91 certificates and $3,549. A 14 kWh battery, the top of the first tier, earns 95 certificates and $3,705, which is $265 per kWh.
A 20 kWh battery crosses the cliff: 14 kWh count in full and the 6 kWh above 14 count at 60 per cent, 3.6 kWh, so eligible capacity is 17.6 kWh. 17.6 x 6.8 = 119.68, rounded down to 119 certificates, worth $4,641: $232 per usable kWh, against $265 for the 14 kWh unit. A 28 kWh battery earns 152 certificates and $5,928, and a 50 kWh battery earns 174 and $6,786, after which the subsidy stops growing.
Installed in January 2027 instead, the 10 kWh battery earns 57 certificates worth $2,223, $429 less, and the 20 kWh battery earns 100 worth $3,900, $741 less.
Discount by usable capacity, 2026 and early 2027, at $39
The eligible column is what the tiers leave; the two certificate columns use the 6.8 factor for May to December 2026 and the 5.7 factor for January to June 2027. The last column is the 2026 discount divided by the full usable capacity, which falls from $265 at 14 kWh to $212 at 28 kWh and $136 at 50 kWh.
| Usable | Eligible kWh | 2026 STCs (value) | Jan to Jun 2027 STCs (value) | 2026 $ per kWh |
|---|---|---|---|---|
| 5 kWh | 5 | 34 ($1,326) | 28 ($1,092) | $265 |
| 10 kWh | 10 | 68 ($2,652) | 57 ($2,223) | $265 |
| 13.5 kWh | 13.5 | 91 ($3,549) | 76 ($2,964) | $263 |
| 14 kWh | 14 | 95 ($3,705) | 79 ($3,081) | $265 |
| 16 kWh | 15.2 | 103 ($4,017) | 86 ($3,354) | $251 |
| 20 kWh | 17.6 | 119 ($4,641) | 100 ($3,900) | $232 |
| 28 kWh | 22.4 | 152 ($5,928) | 127 ($4,953) | $212 |
| 40 kWh | 24.2 | 164 ($6,396) | 137 ($5,343) | $160 |
| 50 kWh | 25.7 | 174 ($6,786) | 146 ($5,694) | $136 |
The 14 kWh cliff
Up to 14 kWh every extra kWh of usable capacity adds $265 of discount at $39. From 14 to 28 kWh every extra kWh adds $159, and above 28 kWh it adds $40. Going from a 14 kWh unit to a 15 kWh unit therefore adds only $156 of subsidy, not $265, while the hardware price of the extra kWh is unchanged. The cliff does not make a bigger battery wrong; it means the extra capacity above 14 kWh has to pay for itself through what it stores, not through the rebate.
The practical test is your evening use. A household that draws 10 to 12 kWh between sunset and sunrise fills a 13.5 kWh battery and empties it most days, and gets the full $265 per kWh on all of it. A 20 kWh battery in the same house carries 6 to 8 kWh of capacity it rarely cycles and earns $159 per kWh on that part. The solar with battery page sets the discount against installed prices by capacity, and the solar panel cost pages cover the panels that charge it.
The 2027 step and the windows after it
The factor is 6.8 for batteries installed from 1 May to 31 December 2026, 5.7 from 1 January 2027, a cut of 16 per cent, and then steps down every six months. The install date is the day the system is commissioned and the certificate paperwork signed, so a battery ordered in December and installed in January gets the January factor. On a 13.5 kWh battery the January step costs $585; on 20 kWh it costs $741. Any installer quoting for a December install should say in writing what the price becomes if the job moves into 2027.
| Install window | Factor | 13.5 kWh | 20 kWh |
|---|---|---|---|
| May to December 2026 | 6.8 | 91 ($3,549) | 119 ($4,641) |
| January to June 2027 | 5.7 | 76 ($2,964) | 100 ($3,900) |
| July to December 2027 | 5.2 | 70 ($2,730) | 91 ($3,549) |
| January to June 2028 | 4.6 | 62 ($2,418) | 80 ($3,120) |
| July to December 2028 | 4.1 | 55 ($2,145) | 72 ($2,808) |
| January to June 2029 | 3.6 | 48 ($1,872) | 63 ($2,457) |
| July to December 2029 | 3.1 | 41 ($1,599) | 54 ($2,106) |
| January to June 2030 | 2.6 | 35 ($1,365) | 45 ($1,755) |
| July to December 2030 | 2.1 | 28 ($1,092) | 36 ($1,404) |
State schemes that stack with the federal discount
Western Australia stacks the Residential Battery Scheme rebate on top of the federal discount: up to $1,300 for Synergy customers and up to $3,800 for Horizon Power customers, with the maximum set at 10 kWh of usable capacity, a VPP commitment required, plus a no-interest loan of up to $10,000 for households earning under $210,000. On a 20 kWh battery that is $4,641 federal plus up to $1,300, $5,941 in Perth on Synergy, or up to $3,800, $8,441, in the regions on Horizon Power. The WA rebates page has the scheme conditions.
New South Wales suspended its battery installation discount on 1 July 2025; the Peak Demand Reduction Scheme still pays an incentive for connecting the battery to a virtual power plant, and the VPP provider sets the amount, so nothing is added here. Queensland has no open battery rebate on 27 October 2026 (Battery Booster program closed), so the federal discount is the whole subsidy. South Australia has no open battery rebate on 27 October 2026 (Home Battery Scheme closed), so the federal discount is the whole subsidy. The Northern Territory has no open battery rebate on 27 October 2026 (Home and Business Battery Scheme (HBBS) closed), so the federal discount is the whole subsidy. Victoria has no open battery rebate on 27 October 2026 (Solar Homes Program closed), so the federal discount is the whole subsidy. Tasmania has no open battery rebate on 27 October 2026 (Energy Saver Loan Scheme closed), so the federal discount is the whole subsidy. The ACT has no battery rebate; the Sustainable Household Scheme lends $2,000 to $20,000 at 3 per cent over up to 10 years, which can fund a battery but does not reduce its price. Each line was read on the state's own page on 27 October 2026; pick a state in the calculator to see it with your figures.
Assumptions and sources in plain words
The 6.8 factor, the three tiers, the 50 kWh ceiling, the 5 kWh minimum, the one-battery rule and the schedule of factors to 2030 are read from the Clean Energy Regulator's solar batteries page and the Renewable Energy (Electricity) Amendment regulations that set them, both checked on 27 October 2026. The $39 price is this site's assumption: the open market traded at $39.90 in the week of 19 to 23 October 2026 and the clearing house pays $40, and the installer carries a trading cost. The state lines are from each state's own scheme page, read the same day, and the WA rebate is shown as the scheme's stated maximum because the page prints no per-kWh rate. Eligible kWh is rounded to two decimals in the table and certificates are rounded down after multiplying, as the regulator does. The calculator runs in your browser, sends nothing to a server and stores nothing; it does not check the approved product list or your inverter, which the installer must do.
Battery rebate questions
How much is the battery rebate in 2026?
$2,652 on a 10 kWh battery, $3,549 on 13.5 kWh and $4,641 on 20 kWh at $39 per certificate, for installs between 1 May and 31 December 2026. The factor is 6.8 certificates per eligible kWh and the first 14 kWh count in full.
How is the battery rebate calculated?
91 certificates on a 13.5 kWh battery comes from 13.5 eligible kWh x 6.8, rounded down, then x $39 = $3,549. Above 14 kWh only 60 per cent of each kWh counts, above 28 kWh only 15 per cent, and above 50 kWh nothing.
What is the battery rebate per kWh?
$265 per kWh for the first 14 kWh at $39 per certificate, $159 per kWh from 14 to 28 kWh and $40 per kWh from 28 to 50 kWh. Averaged over the whole battery it is $265 per kWh at 14 kWh and $232 at 20 kWh.
How much does the battery rebate drop in 2027?
$429 on 10 kWh and $741 on 20 kWh: the factor falls from 6.8 to 5.7 on 1 January 2027, 16 per cent, and the install date, not the order date, decides which factor applies.
Can I get a state battery rebate as well?
$1,300 (Synergy) or $3,800 (Horizon Power) in Western Australia, which stacks with the federal discount and requires a VPP commitment; the maximum applies at 10 kWh. NSW pays only a VPP connection incentive set by the provider; Queensland, South Australia, the Northern Territory and Victoria have closed their battery schemes.
Does a bigger battery get a bigger rebate?
$5,928 on 28 kWh against $3,705 on 14 kWh: double the capacity, 60 per cent more subsidy, because the second 14 kWh count at 60 per cent. A 50 kWh battery gets $6,786, and capacity above 50 kWh gets nothing.