There is no universal answer, but there is a way to think about it. The rebate is one of several numbers in the decision, and it is not usually the largest.
What waiting costs
The rebate falls each 1 January. For a 6.6 kW system in zone 3, the certificate value is about $1,700 to $1,800 in 2026 and about $1,370 to $1,440 in 2027, a loss of roughly $340. The following year loses another $340 or so. Waiting also costs the electricity you would have saved over those months. For many households that is several hundred dollars a quarter.
What waiting might gain
Hardware and installation prices may fall, tariffs may change, and you may find a better design or a cheaper battery option. But these are guesses, and the rebate drop is a certainty.
A simple decision approach
- Gather 12 months of bills and note how much power you use during the day.
- Get two or three quotes with the install date and the STC count shown.
- Work out the payback from the after-rebate price and your savings.
- If the payback is acceptable and you can be commissioned before 1 January, go ahead. If not, wait and revisit.
Battery decisions are separate
If you want a battery too, check the factor schedule: 6.8 at the time of writing, 5.7 from 1 January 2027, 5.2 from 1 July 2027. See is a battery worth it.
Questions to put to installers
Ask each installer for the STC count and the date assumption, the expected generation, the warranty on panels and inverter, and the accreditation number. A clear, written answer to each lets you compare on substance, not urgency. If someone refuses to give the numbers, that tells you something too.
What this means for you
Use the rebate schedule as one input, not the whole story. See the schedule by year, what the January drop does and the STC trading pillar. Check the STC quote explainer to understand the discount on your quote.