Certificate volumes are the supply side of the market, and the numbers have been moving.
The numbers
| Year | STCs created | Notes |
|---|---|---|
| 2024 | 34.1 million | About 656,000 a week; 8.6 million in Q4 |
| 2025 | 25.0 million | About 472,000 a week; 6.9 million in Q4 |
| 2026 | 24.1 million (estimate) | Basis for the 11.67 per cent STP |
These are from the Clean Energy Regulator’s quarterly carbon market reports and the STP calculation. The 2025 and 2026 figures exclude STCs created under the Cheaper Home Batteries Program, which the government buys rather than liable entities. Verify the latest number in the regulator’s current report, because quarterly figures get revised.
Why 2025 fell
Around 269,000 small-scale solar systems with 2.8 GW were installed in 2025, compared with 319,000 systems and 3.2 GW in 2024. Fewer systems and, as importantly, a shorter deeming period (six years for 2025 installs against seven for 2024) meant fewer certificates per system. We explain how the period shortens each year in the deeming period guide and why the rebate drops every year.
What is in and out
STCs come from rooftop solar, solar hot water and heat pumps, and from 1 October 2026 from solar above 100 kW up to 1 MW as well, as set out in mid-scale solar STCs. Battery STCs, created from 1 July 2025, are tracked separately because the government buys them. If you see a total that looks higher than these, check whether batteries are included.
What the volumes mean
The more certificates created, the more retailers must buy, and the STP is set to match that forecast, as in how the STP is calculated. If creation outstrips the forecast, the Clearing House queue lengthens and the price eases below $40. See what drives STC prices.
How to track it yourself
The regulator publishes quarterly carbon market reports with the number of STCs created in the quarter, the number of installations and the average per week, as well as the Clearing House volume. Its STC projections reports from consultants give forecasts several years out. If you want the live count, the REC Registry’s public data shows certificates created by month. Compare the same quarter across years, because installation volumes are seasonal and a single quarter can mislead.
What this means for installers
Volumes tell you the market is large and well supplied, and that the scheme is shrinking towards 2030 on schedule. For your own claims, the quantity per system comes from the STC calculator. For selling, check the pricing page and how STC trading works.