The schedule is simple and it is fixed in law: one year less every 1 January.
The table
| Install year | Deeming period | 6.6 kW zone 3 STCs | At $38 to $40 |
|---|---|---|---|
| 2026 | 5 | about 45 | $1,700 to $1,800 |
| 2027 | 4 | about 36 | $1,370 to $1,440 |
| 2028 | 3 | about 27 | $1,030 to $1,080 |
| 2029 | 2 | about 18 | $680 to $720 |
| 2030 | 1 | about 9 | $340 to $360 |
The count is kW x zone rating (1.382 for zone 3) x deeming period, rounded down. Zone ratings are 1.622, 1.536, 1.382 and 1.185 for zones 1 to 4. Price is the market range at the time of writing, which can move.
What the table tells you
The step down is largest in percentage terms in the later years. 2027 loses 20 per cent against 2026, but 2030 loses half against 2029. For the first few years the rebate is a meaningful part of a solar quote, and by 2029 and 2030 it becomes a small one. Hardware price changes may offset some of this, though nobody can promise that.
The scheme closes on 31 December 2030. After that, solar customers rely on savings and any state schemes, not on STCs.
Dates and traps
Always use the commissioning date. Check the regulator’s published schedule if you are quoting close to a changeover, and re-confirm before signing a contract that straddles a January.
Using the table for business planning
Installers can use the table to forecast STC revenue per solar job through to 2030. Multiply by your expected volume, subtract trader margin and add battery, hot water and heat pump certificates. The pattern shows why many businesses are shifting mix toward batteries and heat pumps as the solar rebate shrinks.
What this means for installers and homeowners
Plan sales and installs around each 1 January. See the 2026 detail, what a solar rebate drop means, the deeming period resource and the STC trading pillar. To see what a certificate pays today, check pricing.