The STC price has barely moved in seven years. The value of a solar job has fallen by more than half. Both statements are true, and mixing them up is the reason many people think the rebate is “falling because the market fell”. It is falling because the number of certificates per system is falling by design.
This guide walks through the price story from 2019 to 2026, then separates the two effects with numbers. Price ranges below are approximate and drawn from public market commentary and Clean Energy Regulator (CER) reporting. For daily closes, use the CER’s quarterly carbon market reports.
The structure that holds the price
STCs are an unusual market because the government runs a fixed-price window. The STC Clearing House transacts at $40 per certificate (ex GST), and the price is set by regulation. That caps the market in normal conditions: nobody needs to pay more than $40 when they can buy from the clearing house. It also gives sellers a fallback, because a seller who cannot get close to $40 elsewhere can lodge there and wait in the queue. The clearing house is slow, so spot trades just under the ceiling when supply is tight and drifts lower when the market is oversupplied.
Demand comes from liable entities, mainly electricity retailers, who must surrender STCs each year in proportion to their sales. The proportion is the Small-scale Technology Percentage (STP), which the regulator sets annually. A 2026 STP of about 11.67% has been reported. Supply comes from installers creating certificates. For the scheme background, see the installer guide to the STC scheme.
Phase by phase
| Period | Approximate spot behaviour | Drivers |
|---|---|---|
| 2019 | Mid to high $30s | Record solar installs, clearing house deficit and surplus swings |
| 2020 to 2021 | Mid to high $30s, occasional dips lower | Pandemic disruption, then strong rooftop demand |
| 2022 to 2023 | High $30s | Steady supply, retailers buying forward |
| 2024 | Close to $40 | Tighter supply relative to liability, clearing house in deficit |
| 2025 | About $38 to $40 | Battery program starts 1 July 2025, adding a large new supply of certificates |
| 2026 | Roughly $38 to $40 | Battery volume high, ceiling holds |
The CER has reported STCs trading at or near the $40 effective ceiling for close to two years to 2025. Anyone selling in that period was buying a good price relative to history. Treat the table as a map of regimes, not a price feed.
The part that actually fell: certificates per job
The deeming period is the number of years of expected output counted when a system is installed. It is the end year of the scheme, 2030, minus the install year, plus one: 12 years for 2019, 5 years for 2026, 1 year for 2030. A 6.6 kW system in zone 3 (rating 1.382) creates this many certificates:
| Install year | Deeming years | STCs | Value at an illustrative $38 |
|---|---|---|---|
| 2019 | 12 | 109 | $4,142 |
| 2020 | 11 | 100 | $3,800 |
| 2021 | 10 | 91 | $3,458 |
| 2022 | 9 | 82 | $3,116 |
| 2023 | 8 | 72 | $2,736 |
| 2024 | 7 | 63 | $2,394 |
| 2025 | 6 | 54 | $2,052 |
| 2026 | 5 | 45 | $1,710 |
Same system, same price, and the discount has dropped by $2,432. We used a constant $38 on purpose, to show the deeming effect on its own. Real prices moved a little around that figure each year.
This is why “the rebate fell” and “the STC price held up” are both accurate. See the deeming period schedule to 2030 for what is left.
What the price does to an installer’s margin
A crew selling 50 solar systems a month at about 45 STCs a job moves 2,250 certificates a month. A $1 change in the rate is $2,250 a month, or $27,000 a year. A change in the deeming period, from five to four years in 2027, removes 20% of the certificates on the same jobs, equivalent to a $7.60 fall in the price per STC on the same book. Deeming matters more to the business than the typical price swing, and rate negotiations that chase a few cents are a small part of the picture. See installer cash flow for how timing affects it.
What about the trader’s rate?
The spot price is a market reference, not what an installer is paid. Traders pay a published rate below spot, covering their risk and service. The gap changes with competition and with settlement speed. Read the real current rate on the pricing page and not from an article. A page like this should never tell you what you will be paid today.
Batteries changed the supply side
Before July 2025, STC supply was almost entirely rooftop solar and hot water. The Cheaper Home Batteries Program added battery certificates at scale: a 13.5 kWh battery creates 91 STCs, equal to two typical solar jobs. The market absorbed it without breaking the ceiling, partly because the program’s factor falls every six months (6.8 at the time of writing, 5.7 from 1 January 2027, 5.2 from 1 July 2027), which tapers new supply. See the tier explainer.
What could move the price from here
- Supply. Battery and mid-scale solar volume. From 1 October 2026 solar above 100 kW up to 1 MW can create STCs with a fixed five-year deeming period, which adds a block of certificates once applications open in mid to late November. A 250 kW system creates about 1,727 STCs in zone 3.
- Demand. The STP, set each year, and retailer sales.
- Pull-forward. Installs rushed ahead of 1 January each year, which bunch certificates in December.
- Policy. Any change to the scheme or the clearing house.
None of these is predictable to the dollar. See what an STC is worth in 2026 and the price forecast for current thinking, and the glossary for terms.
How to read a price chart without being misled
Three habits help when someone shows you an STC price chart.
- Check the series. Is it the spot price, the clearing house price or a particular trader’s offer? A chart of a trader’s rate says little about the market.
- Check the axis. STCs move in a narrow band, so a chart that starts at $30 makes a $2 change look dramatic. Over seven years the range has been a few dollars, not tens.
- Check the date. A price from last quarter is history. The market moves daily, and your rate should come from a trader’s current published rate on the pricing page.
For exact historical closes, use the CER’s quarterly carbon market reports. They publish the weekly or daily spot statistics and the clearing house position. For the plain-English answers, see the current STC price and trading price versus the clearing house.
One more point is worth making. The best defence against a soft market is a short settlement term. A trader who pays within a day cuts the time you are exposed to price movement on certificates already created.
What to do next
- Compare the value of a job across years by using the number of STCs, not just the price.
- Check the rate you are paid against the clearing house price and the spot range, then ask what your trader deducts.
- Read how long STC payment should take, because the timing of money matters as much as the rate.
- See STC trading and the current rate on pricing, or start trading.