Most rebate calculators give you a number and no working. This page shows every input behind the SolarClaim estimate, where it comes from, and where it can be wrong. If a factor changes, this page changes with the calculator.
The Cheaper Home Batteries Program (CHBP) does not pay you money. An eligible battery creates Small-scale Technology Certificates (STCs), you assign the right to create them to a registered agent, and the agent hands your installer an upfront discount worth roughly the market value of those certificates. It lands on your invoice as a line item. You never receive a cheque.
Rebate = (usable kWh, tiered) x 6.8 STCs per kWh x STC price
The CHBP rate steps down every six months. From 1 May 2026 to 31 December 2026 the rate is 6.8 STCs per usable kWh. It falls to 5.7 in the first half of 2027, then 5.2 in the second half, and keeps stepping down every six months to 2.1 by the end of 2030, when the scheme ends. Installing earlier is worth more, which is the single most useful thing to know about this scheme.
Note the word usable. The rebate is calculated on usable capacity from the battery datasheet, not the nominal or nameplate figure. Quoting the nominal number is the most common reason a homeowner's own estimate comes in high.
Since 1 May 2026 the rate is tiered, so a bigger battery does not earn proportionally more.
| Usable capacity | Rate applied | Effective STCs per kWh |
|---|---|---|
| First 14 kWh | 100% | 6.8 |
| 14 kWh to 28 kWh | 60% | 4.08 |
| 28 kWh to 50 kWh | 15% | 1.02 |
| Above 50 kWh | Nil | 0 |
Most home batteries are 10 to 15 kWh usable, so most households sit entirely or almost entirely in the full-rate tier.
STCs trade on an open market, typically between $35 and $40, and clearing agents take a margin. We use $38 as a midpoint. The live spot price is published at the REC Registry. A $3 swing in the certificate price moves the rebate on a 13.5 kWh battery by roughly $275, which is the largest single source of variance in any estimate you will see, including ours.
Panels earn certificates under a separate, older scheme:
STCs = system size in kW x zone rating x deeming years
Deeming years in 2026: 5. The scheme ends on 31 December 2030 and the deeming period drops by one each calendar year (4 in 2027, 3 in 2028, and so on).
Zone ratings come from the Clean Energy Regulator's postcode zone table:
| Zone | Rating | Typical coverage |
|---|---|---|
| 1 | 1.622 | NT, far north QLD, northern WA |
| 2 | 1.536 | Most of QLD, inland SA, inland WA |
| 3 | 1.382 | Sydney, Brisbane, Perth, Adelaide, coastal |
| 4 | 1.185 | Melbourne, Hobart, alpine and southern |
Without a postcode we apply your state's capital-city zone, which is why the postcode field, though optional, sharpens the result in QLD, WA and SA where a state spans multiple zones.
| State | What is on offer |
|---|---|
| WA | Residential Battery Scheme: up to $1,300 for Synergy customers, up to $3,800 for Horizon Power customers. VPP enrolment required. |
| NSW | Peak Demand Reduction Scheme: typically several hundred dollars, up to around $1,100 net, for a VPP-connected battery, paid through your VPP provider or certificate agent. From June 2026 eligible households can also take a zero-interest Home Energy Saver loan of up to $15,000 (financing, so excluded from estimates). |
| ACT | Low-interest (3%) loan of up to $20,000 (was interest-free up to $15,000 before 1 July 2026). A financing benefit, not a discount, so we do not add it to your estimate. |
| QLD, VIC, SA, TAS, NT | No active state battery rebate. Federal CHBP only. |
Run your own numbers. The calculator applies every factor on this page in about 30 seconds.