How the federal solar rebate (STCs) actually works

When people talk about "the solar rebate" in Australia, they are almost always talking about small-scale technology certificates, or STCs, created under the Small-scale Renewable Energy Scheme, usually shortened to SRES. It is a federal scheme, administered by the Clean Energy Regulator, and it is the reason a solar quote already looks discounted before you have started negotiating, rather than reflecting the raw cost of panels, inverter and installation labour added together.

The mechanism is simpler than it sounds, and almost no homeowner deals with it directly. Installing an eligible system creates a number of STCs, calculated from the system's size in kilowatts, the postcode's solar rating zone, and a figure called the deeming period. Rather than you registering and selling those certificates yourself, your installer or retailer takes on that job in exchange for an upfront discount on the quoted price, which is why the rebate shows up as a lower number on your invoice rather than a cheque arriving later.

The deeming period is the part of the scheme that quietly shrinks every year, explaining why the same system attracts a smaller rebate this year than it did last year. It represents the number of years of certificates a system is assumed to generate up front, counting down to when the SRES is legislated to close on 31 December 2030. In 2025 the deeming period was six years; from 1 January 2026 it stepped down to five years, and it is scheduled to fall by a further year on each following 1 January until it reaches one year in 2030, after which no new STCs will be created under the scheme. Each step down reduces both the certificates a system generates and the size of the upfront discount by a broadly similar proportion.

Two other variables move the dollar value around. The certificate price floats within a legislated cap rather than sitting at a fixed figure, so the market price used on any given day is not identical to what a neighbour paid months earlier. And because the calculation is postcode-based, reflecting typical solar irradiance in a given zone, identical systems in different parts of the country can generate slightly different certificate numbers. A legitimate quote should show the STC discount as a clearly separated line item, and the Clean Energy Regulator publishes a public calculator to sanity-check the figure yourself.

Eligibility comes with a catch worth taking seriously. Only systems designed and installed by an accredited installer, using products drawn from the regulator's approved product lists, can generate STCs at all. An installer who is not properly accredited, or who fits gear not on the approved lists, cannot legitimately create certificates for your system, which either means no rebate lands or means someone has claimed it using your details improperly. Checking an installer's accreditation before signing is covered in our separate article on the topic.

The rebate is not means tested, and it is available to homeowners and small businesses installing eligible systems up to 100 kilowatts. The only genuine time pressure is the gradual, scheduled decline described above, a modest reason to avoid dragging out a decision indefinitely, not a reason to sign with whoever knocks first or undercuts every other quote by a suspiciously wide margin. Because the scheme's figures move every year, check the current deeming period and an up-to-date rebate estimate through an installer's quote or the regulator's own calculator, rather than a number from a previous year. Our directory lists solar installers by area if you are ready to compare quotes.

Frequently asked questions