Each year the Clean Energy Regulator counts one fewer year of deemed generation when it calculates STCs for small-scale solar. That is the whole mechanism behind the “falling rebate”.
The schedule from here
| Install year | Deeming period | Change from prior year |
|---|---|---|
| 2026 | 5 years | down 1 |
| 2027 | 4 years | down 1 |
| 2028 | 3 years | down 1 |
| 2029 | 2 years | down 1 |
| 2030 | 1 year | down 1 |
| 2031 | none | scheme ended 31 Dec 2030 |
The system calculation is kW times zone rating times deeming years, rounded down. See the STC formula.
What each year means in practice
2026 (5 years). A 6.6 kW system in zone 3 creates 45 STCs. At roughly $38 to $40 an STC at the time of writing, that is about $1,700 to $1,800.
2027 (4 years). The same system creates 36 STCs. At the same price the discount falls by about 20 per cent, around $1,370 to $1,440. Read what changes in January 2027.
2028 (3 years). 27 STCs, about $1,030 to $1,080.
2029 (2 years). 18 STCs, about $685 to $720.
2030 (1 year). 9 STCs, about $340 to $360. The last year of the scheme.
The dollar amounts assume the price stays near $38 to $40, which is a guide, not a forecast. Every step is a mechanical fall in the number of certificates, not a price move. For a full table by zone, see STCs for a 6.6 kW system by year.
What this means for installers
Each January the same job loses about a fifth, then a quarter, then a third of its STC value. Customers who delay a year do so at a real cost, and a good proposal says so. Plan the sales pipeline so quotes signed in December are installed and commissioned before the rate steps down; the deeming year follows the installation date, not the contract date. Check the numbers with the STC calculator.
For the rest of the picture, see the deeming period pillar, rates on pricing and start trading.