How the STC discount works
When you install eligible solar panels, a battery, a solar water heater or a heat pump water heater, the system creates STCs. Electricity retailers must buy STCs each year to meet their obligations under the Renewable Energy Target, which gives the certificates their value.
Almost everyone assigns their STCs to the installer in return for an upfront discount. You sign an assignment form, and the installer creates and sells the certificates. You can also create and sell them yourself, but you wait to be paid and carry the price risk.
How many STCs your solar panels earn
STCs = system size in kW × zone rating × deeming years, rounded down to a whole number.
| Zone | Rating | Covers |
|---|---|---|
| Zone 1 | 1.622 | Alice Springs and the arid centre |
| Zone 2 | 1.536 | Darwin, Broome and the tropical north |
| Zone 3 | 1.382 | Sydney, Brisbane, Adelaide, Perth, Canberra and most of NSW, QLD, SA and WA |
| Zone 4 | 1.185 | Melbourne, Hobart, Geelong and the rest of Tasmania and southern Victoria |
| Installed in | Deeming years | Zone 3 STCs | Zone 4 STCs | Zone 3 value at $40 |
|---|---|---|---|---|
| 2026 | 5 | 45 | 39 | $1,800 |
| 2027 | 4 | 36 | 31 | $1,440 |
| 2028 | 3 | 27 | 23 | $1,080 |
| 2029 | 2 | 18 | 15 | $720 |
| 2030 | 1 | 9 | 7 | $360 |
The deeming period is the number of years of output the system is credited for up front. It was 15 years in 2016 and drops by one each year, which is why the discount gets smaller every January.
What an STC is worth
The Clean Energy Regulator runs a Clearing House where STCs sell for a fixed $40 excluding GST, but sellers may wait for a buyer. Most certificates trade on the open market, usually a little below the Clearing House price, so installers often value them slightly under $40.
What earns STCs
Solar panels
Up to 100 kW- Deemed output for the years left in the scheme
- Applies to new systems and extra panels
- Falls each January until 2030
Batteries
From July 2025- STCs per usable kWh, the Cheaper Home Batteries Program
- Must be connected to solar
- Factor drops twice a year
- Tapers above 14 kWh
Solar water heaters and air source heat pumps also earn STCs, scaled by the same falling deeming period. From 1 October 2026, mid-scale solar systems up to 1 MW can also create STCs. Batteries are covered in our battery rebate guide and the Cheaper Home Batteries Program page. Hot water is covered in solar and heat pump hot water.
Rules for the discount
The installer must be accredited with Solar Accreditation Australia, the panels and inverter must be on the approved products lists, and the STCs must be created within 12 months of installation.
Common questions
It depends on system size, postcode and install year. In 2026 a 6.6 kW system creates 45 STCs in Sydney, worth up to $1,800 at the $40 Clearing House price, and 39 in Melbourne.
The Small-scale Renewable Energy Scheme runs to the end of 2030. The deeming period falls by one year each January, so the discount shrinks each year until then.
No. Most people assign them to the installer, who takes the value off the price. You sign an STC assignment form when the system is installed.
No. Any home or business installing an eligible system with an accredited installer can get it.
Sources
Every rule and figure on this page comes from the Clean Energy Regulator. Last checked October 2026. Prices include GST unless we say otherwise.
- Clean Energy Regulator, calculate small-scale technology certificate entitlements
- Clean Energy Regulator, Small-scale Renewable Energy Scheme
- Clean Energy Regulator, postcode zone ratings and postcode zones for solar panel systems
- Clean Energy Regulator, buy and sell small-scale technology certificates
- Clean Energy Regulator, solar water heaters and air source heat pumps