The question comes up two ways: whether you can claim for a battery installed before 1 July 2025, and whether you can backdate. The answer to both is no, and the reason is the commissioning date.
The rule
The Cheaper Home Batteries Program began on 1 July 2025. Batteries commissioned from that date can create battery STCs. A battery that was already installed and operating before it was not eligible, and the program does not allow a retrospective claim for it. Reported transitional arrangements covered batteries installed shortly before the start date but not switched on until after it, so what counts is the commissioning date, not the date you paid or signed.
Why backdating does not work
STCs are created from a registered, evidenced installation. The installation date, serial numbers and photos are part of the claim, and the regulator checks them. An installer cannot lodge an after-the-fact claim for a battery that was running before 1 July 2025 without misdescribing it. If the commissioning date on the paperwork does not match the real one, it can be picked up in an audit; see how STC audits work.
What you can still do
- Add capacity. If your earlier battery never received a discount, additional capacity of at least 5 kWh can qualify, up to 100 kWh nominal in total. See expanding an existing battery.
- Check state schemes. Some state programs are still open and some have closed. WA’s is active and VPP-required at the time of writing. Check the scheme’s official page.
- Look at a VPP. Joining a virtual power plant can add earnings even where there is no STC discount. See the VPP incentive stack.
Timing questions for new buyers
If your battery is not yet installed, the date that counts is the commissioning date, and it also sets the factor. The factor is 6.8 for May to December 2026, 5.7 from 1 January 2027, 5.2 from 1 July 2027 and lower after that. A battery that is installed in December but not commissioned until January earns the lower factor. See the 2026 factor and the program end date.
What this means for installers
If a customer enquires about an older battery, establish the commissioning date before talking price. Keep the original invoice and any commissioning or network documents. For new jobs, build the schedule around the factor change dates, and check evidence against the battery submission guide.
What this means for you
If you installed before the program, the main lever left is added capacity. If you are buying now, the lever is timing. Run both through the battery STC calculator, and read the battery STCs pillar for the program as a whole. Installers who want a settlement partner can see /start-trading/.