Where the previous page walks through the method, this one gives you the formula and a reference table so you can sanity-check any online calculator.
The formula
Rebate = (tiered usable kWh x factor) x STC price
Tiered usable kWh = the first 14 kWh at 100%, plus the next 14 kWh at 60%, plus the next 22 kWh at 15%, capped at 50 kWh in all. Factor = 6.8 for installs from 1 May to 31 December 2026, 5.7 for January to June 2027 and 5.2 from 1 July 2027.
Reference table
Prices use $39 per STC, the middle of the $38 to $40 range at the time of writing.
| Usable size | 2026 STCs | 2026 value | 2027 STCs | 2027 value |
|---|---|---|---|---|
| 10 kWh | 68 | about $2,650 | 57 | about $2,200 |
| 14 kWh | 95 | about $3,700 | 79 | about $3,100 |
| 20 kWh | 119 | about $4,650 | 101 | about $3,900 |
| 28 kWh | 152 | about $5,900 | 127 | about $5,000 |
| 50 kWh | 174 | about $6,800 | 146 | about $5,700 |
Tests for a good calculator
A sound calculator asks for usable capacity rather than the model name, applies the tiers, asks for the install date, and says which STC price it assumes. Treat one that shows the same dollar-per-kWh at every battery size as out of date, because the tiers began on 1 May 2026.
A calculator also cannot know your eligibility. The battery must be CEC approved and VPP-capable, paired with a new or existing solar system, installed by an accredited installer, and the property must not have claimed before.
Reading a quote against the table
If a quote for a 14 kWh battery in 2026 shows a discount well below $3,600, ask why. It may be a trader margin, a smaller usable capacity or a different STC price assumption. If it is well above, check whether the installer is bundling other incentives into one line, because that makes the quote harder to compare.
What this means for you
Use the table to size a battery and to read a quote. If the STC count on the quote is below the table figure, ask why. It may be a different usable capacity, or a rounding difference, but it is worth knowing. The battery STC pillar explains the scheme, the pricing page shows what installers are paid for certificates, and how it works shows the settlement path.