Battery certificates under the Cheaper Home Batteries Program use a simpler calculation than solar: usable capacity in kWh multiplied by the STC factor for the year of installation, with a cap on the eligible capacity.
The formula
Eligible usable kWh x STC factor. For 2026 installs the factor is 6.8. From 1 January 2027 it is 5.7 and from 1 July 2027 it is 5.2, and it keeps stepping down every six months to 2030. Only the first 50 kWh of usable capacity counts, even though batteries from 5 to 100 kWh are allowed.
| Battery (usable) | 2026 STCs | 2027 STCs |
|---|---|---|
| 5 kWh | 34 | 28 |
| 10 kWh | 68 | 57 |
| 13.5 kWh | 91 | 76 |
| 50 kWh | 340 | 285 |
At roughly $38 each, a 10 kWh battery in 2026 carries around $2,580 of certificate value, which is where the roughly 30% discount at launch came from. Prices move, so recalculate before you quote.
Eligibility checks
The battery must be on the Clean Energy Council approved list, be capable of connecting to a virtual power plant, be installed by an accredited installer, and be one per property. It can be paired with new or existing solar. New photo and evidence rules applied from 1 March 2026; see the battery photo guide.
Use usable, not nameplate
The calculation runs on usable capacity from the approved listing, not the headline number on the box. Quoting from the brochure figure is a classic way to overpromise a discount.
What this means for you
For installers, the size of these certificate values makes cash flow a real issue; Energy Merchants’ battery STC desk is set up for it. See the live rate and the installer guide to the program.
Prices move, so treat any number here as a snapshot and check the live figure before you quote a job.
Pairing a battery with solar does not reduce the solar certificates, since they are calculated separately. Both can be claimed on the same property provided each meets its own rules, which makes the combined upfront discount larger than either alone.
A final trap is the difference between nameplate and usable capacity. Several popular batteries quote a total capacity that is higher than the usable figure the program counts. If you calculate from the larger number, your estimate will be too high and the customer will notice when the invoice arrives. Always use the usable value from the approved list.