If you have been quoting solar since 2019, the STC price will feel like the most boring number in your business. It has hardly moved. What has moved is the number of certificates each system creates, and that is what changed your quotes. This article lays out the period year by year so you can see the two forces separately.
We are not reproducing a tick-by-tick chart, because we cannot verify one here. The price bands below are approximate, flagged as such, and the Clean Energy Regulator’s Quarterly Carbon Market Reports are the place to confirm any particular date. Our broader piece on the shape of the STC price covers the early scheme; this one is about the last seven years.
Two numbers, not one
An STC payment on a job is the price multiplied by the certificate count. The count is kW x zone rating x deeming years, rounded down. The price barely changed from 2019 to 2026. The deeming years fell from 12 to 5.
| Install year | Deeming years | STCs, 6.6 kW zone 3 | Value at about $37 to $38.50 |
|---|---|---|---|
| 2019 | 12 | 109 | about $4,000 |
| 2020 | 11 | 100 | about $3,700 |
| 2021 | 10 | 91 | about $3,400 |
| 2022 | 9 | 82 | about $3,050 |
| 2023 | 8 | 72 | about $2,700 |
| 2024 | 7 | 63 | about $2,400 |
| 2025 | 6 | 54 | about $2,050 |
| 2026 | 5 | 45 | about $1,730 |
| 2027 | 4 | 36 | about $1,390 |
Zone 3 uses a rating of 1.382, which covers Sydney, Brisbane, Perth, Adelaide and Canberra. The values assume a price between $37 and $38.50, the broad band for the period. The point to take is the last column. A standard system’s certificate value has fallen by more than half, even though the price held. That is deeming, not the market.
2019 to 2021: strong volumes, steady price
Rooftop solar installs ran at record levels in these years, and the market absorbed them at prices in the mid to high $30s. Supply was large, but so was demand through the liable entities’ obligations, and the $40 clearing house kept sellers from accepting too little. Installers in this period mostly remember cash flow rather than price: the long deeming period meant a big certificate cheque, and getting it paid quickly mattered more than a dollar either way.
2022 to 2023: the narrow band
Prices traded in a tight band under the ceiling. The gap to $40 reflected what traders charged for speed and for taking on the wait in the clearing house queue. If you are still comparing traders only on headline rate, our piece on the gap between spot and clearing house is worth reading. On a 72-STC job, a $1 difference is $72, and a missed 20-day payment term costs real interest on your own working capital.
2024 to 2025: fewer certificates, new supply
The deeming period kept falling and certificate volumes per install fell with it. Then on 1 July 2025 the Cheaper Home Batteries Program began, creating STCs for batteries from 5 to 100 kWh usable (up to 50 kWh eligible). That added a very large new source of certificates. The Clean Energy Regulator’s response was to raise the small-scale technology percentage assumptions, and the market held up. The price did not collapse under the extra supply, which is a point many forecasters got wrong.
2026: the ceiling holds, the percentage rises
At the time of writing the spot market has been roughly $38 to $40. The 2026 percentage is 11.67%, built on high-scenario projections that anticipate battery volume. Battery claims at a factor of 6.8 (it steps down to 5.7 on 1 January 2027 and to 5.2 on 1 July 2027) make a 14 kWh battery worth about 95 STCs, so a job now often earns more in certificates from the battery than from the solar. For the current number, see what an STC is worth.
From the desk: Do not tell a customer “STCs are lower than they used to be” when what you mean is “there are fewer of them.” Customers hear a price fall and assume the market is weak. The price is fine. The deeming schedule is the reason their discount is smaller, and it is in the regulations years ahead.
What 2027 to 2030 look like from here
The deeming period steps to 4 in 2027, then 3, 2 and 1 in 2030, when the scheme ends on 31 December. A 6.6 kW zone 3 system creates about 36 STCs in 2027 and about 9 in 2030. The price band is only part of the story, so we would not plan around a price move. Plan around the count. The STC calculator lets you run any year, and the January 2027 change shows what the first step costs a standard job.
There is one structural addition: systems above 100 kW and up to 1 MW installed from 1 October 2026 now create STCs with a fixed five-year deeming period (applications open mid to late November 2026, per the CER). Larger commercial jobs add a new source of volume. Read mid-scale solar and STCs if you quote commercial work.
What the seven years mean for cash flow
Because the certificate count fell and the price did not, the cash the average residential job generates has dropped sharply while the work involved has not. A 2019 job needed the same photos, forms and serials as a 2026 job. That squeezes any installer who treats certificate paperwork as a side task. When a claim is worth $1,730 instead of $4,000, a single rejection that adds three weeks to payment is a bigger share of the job’s margin than it used to be. Speed of settlement and first-time clearance have become more valuable as the headline number shrank.
What the history is good for
Use it to set expectations, not to forecast. A seven-year record of a narrow band beneath a hard ceiling tells you that price risk is small and execution risk is large. The big variables in your business are how fast you are paid, whether your claims clear first time, and whether your trader fixes the rate when you lodge. Our trader checklist puts those questions in order.
Related answers
For quick references, see the current STC price in Australia and the deeming period schedule by year.
What to do next
- Run your last year of jobs through the table above to see how much of your discount shrinkage is deeming rather than price
- Check today’s published rate on pricing and write it down with the date
- Read how STC trading works if you want a rate locked on lodgement
- Browse the scheme changes hub for upcoming dates
- For a dated view of what a forecast can and cannot say, see STC price forecast