When a solar quote shows an STC discount, it means the installer has already allowed for the government rebate. It looks like a line reading something like small-scale technology certificates or STC rebate, with a dollar amount or a number of certificates.
What an STC is
An STC is a certificate that the federal government creates for each unit of clean energy a small solar system is expected to produce. It is traded, and it has a market price, at roughly $38 to $40 at the time of writing. The more panels you install and the sunnier your postcode zone, the more certificates you create.
How the number is worked out
The count is system size in kW x zone rating x deeming period. For a 6.6 kW system in zone 3 in 2026 that is about 45 certificates. Zone ratings are 1.622, 1.536, 1.382 and 1.185, and the deeming period is 5 years in 2026, falling to 4 in 2027.
How the discount reaches you
You assign the certificates to your installer by signing a form. The installer sells them through a certificate trader and passes the value to you by reducing the price. You do not have to deal with the registry, and you do not get a cheque from the government.
What to check on the quote
- The number of STCs, and the dollar value used for each.
- Whether the install date and year are stated.
- That the price shown is after the discount and that the quote is clear about what remains payable.
- That the installer is accredited and that your name is on the assignment form.
What this means for you
The STC discount is real money, but it is a falling amount that changes on 1 January each year. See the deeming period explained, when the solar rebate ends and the resources hub for guides. The STC assignment form guide explains what you sign, and what an STC is worth covers the market.