The rebate drops once a year, on a fixed date, by a known amount. There is nothing mysterious about it, and it is easy to plan around.
What drops
Solar rebates are paid as STCs, and the number of STCs depends on a deeming period that shortens each January. The percentages are larger than they look: going from 5 years to 4 is a 20 per cent cut, from 4 to 3 is 25 per cent, from 3 to 2 is 33 per cent, and from 2 to 1 is 50 per cent.
What stays the same
The zone rating for your postcode does not change, and nor does the system size, so the whole movement comes from the deeming period. The market price of a certificate also moves, at roughly $38 to $40 at the time of writing, with a clearing house ceiling of $40.
What it means in dollars
For a 6.6 kW system in zone 3:
| Year | STCs | Approx. rebate at $38 to $40 |
|---|---|---|
| 2026 | 45 | $1,700 to $1,800 |
| 2027 | 36 | $1,370 to $1,440 |
| 2028 | 27 | $1,030 to $1,080 |
| 2029 | 18 | $680 to $720 |
Each step costs roughly $350 on this system in the early years.
Does waiting pay?
It might if panel prices fall faster than the rebate, but that is not guaranteed. Waiting also means paying full power prices for another year. Run both sides of the sum with a quote in your hands.
A note on certificate prices
The deeming period is only half of the story. The certificate price also matters, and it has been roughly $38 to $40 at the time of writing. If the price falls, the rebate falls further. If it rises, which is limited by the $40 clearing house ceiling, the rebate rises. The ceiling means large upside is unlikely.
What this means for you
Treat the rebate as a falling discount, not a deadline. See the schedule, the 1 January drop and should I install now or wait. The STC trading pillar and the deeming period resource give the scheme detail.