STCs on a heat pump or solar hot water system are created up front for the energy the system is expected to save or generate until the scheme finishes. As the end date gets closer, there are fewer years left to count, so each certificate batch gets smaller.
What the end date is
The Small-scale Renewable Energy Scheme runs until 31 December 2030. Systems installed after that do not create small-scale certificates. For the broader picture, see what happens to installers when the scheme ends and the SRES end explainer.
What happens in 2027
For rooftop solar the deeming period is five years for 2026 installs and four for 2027, falling by one a year to one year in 2030. Hot water counts follow the same shrinking runway to the end date, though the exact method depends on the model’s registered data and the CER’s calculation approach. The practical effect is that a heat pump installed in 2027 will generally earn fewer STCs than the same unit installed in 2026. How much fewer depends on the method, so use a current calculator rather than a rule of thumb. See the heat pump STC calculator and deeming period and zone ratings. The solar detail is in what changes in January.
Count versus price
Two things move separately.
| Factor | What moves it |
|---|---|
| Number of STCs per job | Installation year, model, zone, type |
| Dollar value per STC | Market supply and demand, capped by the $40 clearing house ceiling |
The market has been roughly $38 to $40 at the time of writing. A lower count with a steady price means a smaller discount. A falling price with the same count does the same.
Should you bring a job forward
If you were already going to replace an ageing system, an earlier install in 2026 will generally earn more certificates than waiting. But the saving is modest compared with the cost of the system, and rushing a decision to chase it can lead to a poor product or a rushed install. Replace failed units promptly, and plan non-urgent ones with the timing in mind.
From the desk: installers who quote a fixed STC discount in December for a January install should check the count again at install. The year on the install date sets the count, not the year on the quote.
What this means for installers
Plan your pipeline for a gradual decline and an end date, not a cliff. Keep claims moving, since the 12-month window and the date of install both matter. Check live rates on pricing, see how it works and the hot water STC pillar. Longer term, see the STC market after 2030.
Checking the current count
Before signing, ask your installer to show the STC count for the exact model, your postcode and the planned install date. Then run the same inputs through the calculator. If both agree, the discount on your quote is real.