Key points
- The STC solar rebate is calculated as system size (kW) × zone rating × deeming years. Systems installed in 2026 get a 5-year deeming period.
- A 6.6kW system earns about 45 STCs in Adelaide (roughly $1,800) and 39 STCs in Melbourne (roughly $1,550) at October 2026 prices.
- The deeming period drops by one year every 1 January, so a 2027 installation earns about 20% fewer certificates. The scheme ends in 2030.
- It is not a government cheque. You assign the certificates to your installer, who takes their value off your quote.
- From 1 October 2026, solar systems up to 1 MW can earn STCs, up from 100 kW.
The STC solar rebate is the federal discount on almost every rooftop solar system in Australia. Your system earns small-scale technology certificates (STCs) based on its size, your location and the year it is installed. Your installer then buys them from you as a discount on the price. In 2026 a typical 6.6kW system earns about 45 STCs in Adelaide and 39 in Melbourne. That is worth around $1,550 to $1,800. Here is exactly how the number is worked out, so you can check any quote yourself.
What is the STC solar rebate?
STCs are created under the federal Small-scale Renewable Energy Scheme, which the Clean Energy Regulator (CER) runs. One STC represents 1 megawatt-hour (MWh) of renewable electricity that your system is expected to generate. Electricity retailers have to buy and surrender a set number of STCs every year. That legal demand is what gives each certificate a cash value.
So the “rebate” isn’t paid out of a government budget and it isn’t means-tested. Any household or business that installs an eligible system can claim it. This guide focuses on how STCs work for rooftop solar. It is part of our complete guide to solar and battery rebates in SA and Victoria, which covers every other incentive as well.
How are STCs calculated?
The CER formula for a solar panel system is simple:
STCs = system size (kW) × zone rating (MWh per kW) × deeming period (years), rounded down to a whole number.
- System size is the rated capacity of your solar panels, in kilowatts.
- Zone rating reflects how much sun your postcode gets. The CER splits Australia into four zones.
- Deeming period is how many years of generation you are credited for up front. It shrinks each year until the scheme ends in 2030.
| City | STC zone | Zone rating (MWh per kW) |
|---|---|---|
| Adelaide | Zone 3 | 1.382 |
| Melbourne | Zone 4 | 1.185 |
Melbourne gets less sun across the year than Adelaide, so the same system earns about 14% fewer certificates there. Regional areas may sit in a different zone, so always check your postcode on the CER’s zone list.
Worked example: 6.6kW in Adelaide in 2026
- System size: 6.6 kW
- Zone rating for Adelaide: 1.382
- Deeming period for a 2026 installation: 5 years
- 6.6 × 1.382 × 5 = 45.6, rounded down to 45 STCs
- 45 × about $39.85 = about $1,790 off the price
The same system in Melbourne is 6.6 × 1.185 × 5 = 39.1, which rounds down to 39 STCs, or about $1,550.
How much is the STC rebate worth in 2026?
In early October 2026 STCs were trading at about $39.85 to $39.90 on the open market. That is just under the $40 (excluding GST) fixed price in the CER’s STC Clearing House. Here is what common home system sizes earn if installed before 31 December 2026:
| System size | Adelaide STCs | Approx. value | Melbourne STCs | Approx. value |
|---|---|---|---|---|
| 6.6kW | 45 | $1,790 | 39 | $1,550 |
| 10kW | 69 | $2,750 | 59 | $2,350 |
| 13kW | 89 | $3,550 | 77 | $3,070 |
Values use $39.85 per STC and are indicative. The discount on your quote may be a little lower. The installer or their agent takes a margin and carries the risk that the price moves before they sell. If you are weighing up sizes, our guide on what size solar system you need explains how to match a system to your usage.
Why does the STC rebate get smaller every year?
The deeming period falls by one year every 1 January. The scheme is legislated to end after 2030, so each year your system is credited with one less year of generation.
| Year installed | Deeming period | 6.6kW Adelaide STCs | 6.6kW Melbourne STCs |
|---|---|---|---|
| 2026 | 5 years | 45 | 39 |
| 2027 | 4 years | 36 | 31 |
| 2028 | 3 years | 27 | 23 |
| 2029 | 2 years | 18 | 15 |
| 2030 | 1 year | 9 | 7 |
If STC prices stay near $40, a 6.6kW system in Adelaide installed in January 2027 gets about $360 less than one installed in December 2026. For a 10kW system the gap is about 14 STCs, or roughly $560.
Your installation date sets your deeming period, not the date you sign the contract. The CER says it monitors installation dates to make sure the correct deeming period is applied, and that giving false information is an offence. If an installer promises “this year’s rebate” for a job they can’t install until January, that promise is worth nothing.
Tip: Don’t let the January drop push you into a rushed decision. A few hundred dollars matters, but a poor-quality system costs far more over 25 years. Get your quotes in by early November so there is time to compare them properly and still install before the end of the year.
How does the STC discount show up on your quote?
Almost nobody claims STCs personally. The CER says most people assign the right to create their STCs to a “registered agent”, usually through their installer, in exchange for an upfront discount. You sign an STC assignment form, and the discount appears as a line on your quote or invoice.
A good quote should show:
- the price before STCs
- the number of STCs and the dollar value per certificate
- the price you actually pay after STCs
Run the formula yourself to check the number. If a quote for 6.6kW in Melbourne claims 45 STCs, either the postcode zone or the system size is wrong.
Can you claim STCs yourself?
Yes, but it is rarely worth it. You must open a “registered person” account in the REC Registry. The CER warns verification can take six weeks or longer. The certificates must be created within 12 months of installation. You then sell them on the open market, where prices change daily, or through the STC Clearing House at $40 excluding GST. There is no guarantee of how long a Clearing House sale will take. Most owners take the upfront discount and avoid the paperwork and price risk.
What makes a solar system eligible for STCs?
Under the CER’s rules, a small-scale solar system must:
- be no more than 100 kW, with annual output under 250 MWh (or up to 1 MW under the new mid-scale rules below)
- use panels and inverters on the Clean Energy Council’s approved product list
- be designed and installed by an installer accredited by Solar Accreditation Australia (SAA)
- meet Australian Standards and SAA design and install guidelines
- have its STCs created within 12 months of installation, with geotagged, time-stamped photos and serial numbers as evidence
Design guidelines allow your panel capacity to exceed your inverter capacity by up to a third. That’s why 6.6kW of panels on a 5kW inverter is the standard Australian home system. All 6.6kW earns STCs. Our 6.6kW solar system package is built that way, and larger homes often step up to a 10kW solar system for more certificates and more generation.
STCs for batteries, hot water and businesses
The same certificates now fund other technologies, but the maths differs:
- Home batteries earn STCs per kilowatt-hour of usable capacity under the Cheaper Home Batteries Program. There is no deeming period and no zone rating. The rate is 6.8 STCs per kWh for installs up to 31 December 2026, then 5.7 from January 2027. Our guide to stacking solar and battery incentives shows how solar and battery STCs add up on one quote.
- Heat pump and solar hot water systems earn STCs using a different method set by the CER.
- Business systems from 100 kW to 1 MW became eligible from 1 October 2026. They get a fixed 5-year deeming period. The CER says applications open in mid to late November 2026, and choosing STCs means no REGO certificates for the deeming period. See our explainer on the commercial solar rebate for systems up to 1 MW.
How STCs combine with state rebates
STCs come off first and apply everywhere. What you can add on top depends on your state. In Victoria, eligible owner-occupiers can add the Solar Homes rebate of up to $1,400. See our Victoria solar rebates guide for the July 2026 eligibility changes. South Australia has no state solar rebate, but some councils and retailer schemes add a little. Our guide to solar rebates in South Australia lists what you can still claim there.
Frequently asked questions
Is the STC solar rebate means-tested?
No. Any household, landlord or business that installs an eligible system with an SAA-accredited installer and approved products can earn STCs. There is no income cap or property value limit. This is different from state programs such as Victoria’s Solar Homes rebate, which has a $150,000 household income cap from 1 July 2026.
Do I get a cheque for my STCs?
Usually not. Most people assign their STCs to the installer’s registered agent and get the value as an upfront discount on the invoice. You can create and sell the certificates yourself through the REC Registry, but you must do it within 12 months of installation and take on the price risk and paperwork.
When does the STC rebate end?
The Small-scale Renewable Energy Scheme ends in 2030. Each 1 January the deeming period drops by one year: 5 years for 2026 installations, 4 in 2027, 3 in 2028, 2 in 2029 and 1 in 2030. The rebate shrinks every year rather than stopping suddenly.
Why is my STC discount lower than the market price?
The installer or registered agent pays you before they sell the certificates, so they take a margin and carry the risk that prices fall. Some quotes also show the value excluding GST. Check that the number of STCs matches the formula, then compare the final price across quotes rather than the STC line alone.
Our SAA-accredited installers in Adelaide and Melbourne show the STC count and value on every quote, so you can check the maths yourself. If you would like a system installed before the January step-down, get a free quote and we will work through the numbers for your postcode.
Sources: Clean Energy Regulator – Calculate small-scale technology certificate entitlements (updated 18 Sep 2026); Clean Energy Regulator – Create small-scale technology certificates (updated 12 Oct 2026); Clean Energy Regulator – Buy and sell small-scale technology certificates (updated 14 Sep 2026); Clean Energy Regulator – Small-scale renewable energy systems (updated 18 Sep 2026); Clean Energy Regulator – Mid-scale solar (updated 7 Oct 2026). STC prices move daily and the dollar values above are indicative as of October 2026; check your postcode zone and the current price before relying on them. Featured image: Cboyce89 / Wikimedia Commons, CC BY-SA 4.0.
