Batteries under 14 kWh are the simplest case, because every kilowatt-hour is counted at the full factor. The tier reductions that start at 14 kWh do not apply.
STCs and dollars by size, 2026
The factor is 6.8 for batteries commissioned from 1 May to 31 December 2026. Certificates are rounded down to a whole number. Dollar values use $38 to $40 per STC, which is the range the market has been in at the time of writing. The figures use usable capacity, not the label size.
| Usable kWh | STCs (6.8) | Value at $38 to $40 | STCs in 2027 (5.7) |
|---|---|---|---|
| 5 | 34 | $1,292 to $1,360 | 28 |
| 6.5 | 44 | $1,672 to $1,760 | 37 |
| 8 | 54 | $2,052 to $2,160 | 45 |
| 10 | 68 | $2,584 to $2,720 | 57 |
| 13.5 | 91 | $3,458 to $3,640 | 76 |
You can check any other size on the battery STC calculator.
The 5 kWh battery
A 5 kWh battery is the smallest size the program covers. On a nominal 5 kWh unit the usable capacity may be a little lower, so the real count may be below 34. The rules require the battery system to be 5 to 100 kWh nominal; see nominal versus usable. At around $1,300 to $1,360 the discount is meaningful on a small unit, but a small battery may not cover an evening’s use for a family home.
The 6.5, 8 and 10 kWh batteries
These sizes suit a modest household with solar. They are fully in the first tier, so each added kWh earns 6.8 STCs, about $260 to $270. A 10 kWh unit earns about 68 STCs, or $2,600 to $2,700.
The 13.5 kWh battery
Very close to the 14 kWh edge of the first tier. It earns about 91 STCs at the full rate. Going from 13.5 to 15 kWh adds only about 8 STCs, because the extra capacity is at 60%. See how much for 15 to 28 kWh.
Cost after the rebate
The after-rebate price is the installed price minus the STC discount. A battery quoted at a pre-discount price of X is X less $1,300 to $1,360 at 5 kWh, or less $3,458 to $3,640 at 13.5 kWh. Switchboard upgrades, backup circuits and network fees are not covered by the discount. Your own quote will vary; use the method, not a headline price. A worked example is in how much a battery costs after the rebate.
What this means for installers
For small batteries the margin for error is smaller, so the rounding and usable capacity matter. Use the CEC listed usable figure, not the marketing number, and settle the claim on a known rate; see /pricing/ and /start-trading/.
What this means for you
The factor drops to 5.7 on 1 January 2027 and 5.2 on 1 July 2027, so the same battery earns less the longer you wait. See the battery STCs pillar and the 2027 factor.