The Cheaper Home Batteries Program gives you a discount at the point of sale in the form of small-scale technology certificates. How many depends on three things: the usable capacity of the battery, the factor for the date it is installed, and a tiered scale that now rewards the first 14 kWh most.
The formula in one paragraph
Usable kWh, multiplied by the factor, with each tier weighted. Since 1 May 2026 the first 14 kWh count at 100% of the factor, kWh from 14 to 28 at 60%, and kWh from 28 to 50 at 15%. The factor is 6.8 for installs between May and December 2026 at the time of writing. STCs are rounded down to whole certificates. For more on the tiers, see the three battery rebate tiers.
A 10 kWh battery
All 10 kWh sit in the first tier, so 10 x 6.8 = 68 STCs. At roughly $38 to $40 per STC that is about $2,580 to $2,720.
A 13.5 kWh battery
Still inside the first tier, so 13.5 x 6.8 = 91.8, which rounds down to 91 STCs. That is about $3,460 to $3,640. This size is popular precisely because it sits just under the 14 kWh step.
A 20 kWh battery: worked example
The first 14 kWh earn the full factor and the remaining 6 kWh earn 60% of it.
| Step | Working | STCs |
|---|---|---|
| First 14 kWh | 14 x 6.8 | 95.2 |
| Next 6 kWh | 6 x 6.8 x 0.60 | 24.48 |
| Total | 119.68, rounded down to 119 |
At $38 to $40 that is about $4,520 to $4,760. Compare that with simply doubling the 10 kWh result (136 STCs): the extra 6 kWh adds only 24 STCs, roughly a fifth of what the first 6 kWh would have added.
Where these numbers change
| Install date | Factor | 10 kWh | 13.5 kWh | 20 kWh |
|---|---|---|---|---|
| May to Dec 2026 | 6.8 | 68 | 91 | 119 |
| Jan to Jun 2027 | 5.7 | 57 | 76 | 100 |
| Jul to Dec 2027 | 5.2 | 52 | 70 | 91 |
The date that counts is the install date, so a signed quote does not lock the factor. The 2027 factor page covers the step-downs in detail.
Conditions that apply to every size
The battery must be on the Clean Energy Council approved list, be VPP-capable, be installed by an accredited installer, and be 5 to 100 kWh usable, with up to 50 kWh counted. It is one battery per property and it works with new or existing solar.
What this means for you
Work out your own number in the battery STC calculator, then compare it with the discount on each quote. The battery STC overview explains the program, and the installer guide shows how the paperwork works from the other side. If you want to see how installers convert certificates to cash, our pricing page lists the published rate.