There are two kinds of STC price forecast. One is a number: the price will be $36 by March. The other is a method: here are the five things that move the price, here is how to read each, and here is how to quote so that a wrong guess does not hurt. The first kind is usually wrong. This guide is the second kind.
We already publish a scenario piece, what could move the STC price to 2030, and a record of past prices. This guide sits between them. It shows you which public numbers to watch and how to turn them into a quoting habit. At the time of writing the STC spot market has been roughly $38 to $40, against a clearing house price of $40.
Signal one: the distance to the ceiling
The CER’s STC Clearing House buys at a fixed $40 per certificate, ex GST, so the market cannot sustainably trade above it. Watch the gap between spot and $40. A price at $39.80 says the market is tight and sellers have the upper hand. A price at $37 says buyers are finding certificates easily, or that sellers are pressed for cash.
The gap matters more than the level. On a 45-STC job (a 6.6 kW system in a zone 3 postcode, five-year deeming), each dollar of gap is $45. A three-dollar slip costs $135 a job. For how the ceiling works in practice, read our clearing house guide and the answer on trading price versus clearing house.
Signal two: the liability percentage
Demand for STCs comes from electricity retailers and other liable entities, which must surrender certificates in proportion to the electricity they acquire. The proportion is the Small-scale Technology Percentage (STP), set by the Clean Energy Regulator each year. It was reported at about 11.67% for 2026.
The arithmetic is direct. A retailer acquiring 1,000 MWh surrenders about 116.7 STCs. At $39 that is roughly $4,551, or $4.55 per MWh. If a future percentage is lower, retailers need fewer certificates and demand softens. The regulator sets the percentage from its estimate of how many STCs will be created, so supply forecasts feed into it. A high-volume year can push the next percentage up, and a weak year can pull it down.
Signal three: the deeming schedule
The most predictable driver is the calendar. The deeming period for small-scale solar is five years for 2026 installs, four for 2027, and down by one each year to one in 2030, when the scheme ends on 31 December. The same system creates fewer certificates every January.
| Year installed | Deeming years | STCs for 6.6 kW, zone 3 (1.382) |
|---|---|---|
| 2026 | 5 | 45 |
| 2027 | 4 | 36 |
| 2028 | 3 | 27 |
| 2029 | 2 | 18 |
| 2030 | 1 | 9 |
The count is 6.6 x 1.382 x years, rounded down. Fewer certificates per job, for the same number of jobs, means less supply. That tends to support price. It also means a surge of installs in late 2026 as customers bring jobs forward, which can add temporary supply in the fourth quarter. Our piece on what changes in January covers the pull-forward effect.
Signal four: batteries
Batteries are the large new source of certificates. The Cheaper Home Batteries Program creates STCs on usable kWh multiplied by a factor, which is 6.8 at the time of writing, stepping to 5.7 on 1 January 2027 and 5.2 on 1 July 2027. A 13.8 kWh battery earns 93 STCs at 6.8 and 78 at 5.7.
Battery volumes depend on policy and demand, not just on the calendar. The program budget was expanded from $2.3bn to $7.2bn, as reported, which suggests volumes can stay strong. Watch the CER’s reports for how many battery STCs are being created each quarter. If battery supply rises faster than the liability percentage, the spot price faces downward pressure. See the battery STC factor for 2027 for the schedule.
Signal five: mid-scale solar
From 1 October 2026, systems above 100 kW and up to 1 MW can create STCs with a fixed five-year deeming period, instead of LGCs. The CER has said applications open mid to late November 2026. Systems above 1 MW remain in the LGC scheme. Our pillar page mid-scale solar STCs has the detail.
For supply, take a 500 kW commercial system in zone 3. It creates 500 x 1.382 x 5 = 3,455 STCs, worth about $134,000 at $39. One system equals the certificates from about 77 typical homes. That is new volume, but small against the rooftop market. The effect is worth watching rather than worrying about, and it will not show up in registry data until after the application window opens.
Putting it together: a quarterly routine
- Read the CER quarterly report when it lands and note spot, clearing house and creation figures.
- Check the STP each year and recompute the demand per MWh.
- Update the deeming table for jobs you will lodge in the next quarter.
- Track battery and mid-scale creation from registry releases.
- Record the rate you quoted against and the rate you were paid, so you see the real gap.
From the desk: no signal predicts a week’s move. The point of the routine is to know whether your quoting buffer is sensible. If you quote at spot less $1.50 and your lodged rate is usually within $1, you are holding a buffer you do not need. If it is regularly $3 away, widen the buffer or shorten your quote validity.
Turning signals into quotes
- Quote below spot. Using a rate a dollar or two under spot builds in room for a soft week.
- Itemise the discount. Show the STC line separately and state the rate it assumes.
- Keep quotes short. A 14-day validity carries a fraction of the exposure of a 60-day one.
- Lock early. Choose a trader that locks the rate when you lodge a complete claim, so risk ends at lodgement, not at settlement.
Our published buy rate sits on the pricing page and updates daily. The how it works page explains the lock. If you want to understand where price differences between traders come from, read STC pricing explained.
What to do next
- Bookmark the CER’s quarterly report and the STP page.
- Rebuild your quote template using the deeming table above.
- Read the glossary entry on the clearing house and the STC spot price definition if the terms are new.
- Compare this week’s number with the pricing page and note the date.
For definitions of any term used here, see the glossary.