Under the original design the factor fell once a year. The program now has a step every half year, and the steps are bigger.
The reason
The program was designed as a discount funded by the government through the STC scheme, with the factor declining toward 2030. Demand was much higher than expected. The budget was expanded from $2.3bn to $7.2bn (as reported), and in 2026 the government revised the settings. The factor now falls twice a year, and tiers cap support on larger batteries from 1 May 2026. The point is to make the same budget stretch across more households and to keep the support closer to the cost of a typical battery as hardware prices fall.
There is a second reason built into the design. Because STCs are a market, a steady factor would keep adding certificates at a rate that the scheme and the clearing house have to absorb. Lowering the factor reduces the number of certificates created for the same battery.
The steps so far
| Commissioning period | Factor |
|---|---|
| July to December 2025 | 9.3 |
| January to April 2026 | 8.4 |
| May to December 2026 | 6.8 |
| January to June 2027 | 5.7 |
| July to December 2027 | 5.2 |
Beyond that, the published schedule continues down to 2.1 in the second half of 2030; see 2028 to 2030. A 14 kWh battery earns 95 STCs now, 79 from 1 January 2027 and about 72 from 1 July 2027.
What it means for timing
Every step is a price rise for the customer of about $300 to $600 on a typical 14 kWh battery, assuming hardware prices do not fall. That is the cost of waiting. Falling hardware prices can offset it, but the offset is uncertain. Note the commissioning date sets the factor, so a battery installed in late December that cannot be commissioned until January is on the lower factor.
What this means for installers
Plan your pipeline around the step dates. Jobs that are likely to slip across the boundary should be flagged at the quote stage, with the customer told what the lower factor does to the price. Certificate settlement is not affected by the step; the rate for settlement is published daily on /pricing/, and /start-trading/ shows how to set up.
What this means for you
If the battery makes sense for you now, the arithmetic usually favours doing it earlier. Compare timing using the battery STC calculator, and see the January 2027 cut, the 1 May 2026 changes and the battery STCs pillar.