STC definition

Written and checked by the Energy Merchants desk · Reviewed 2 October 2026

An STC, or Small-scale Technology Certificate, is a tradable certificate created under the federal Small-scale Renewable Energy Scheme (SRES). The Clean Energy Regulator (CER) administers it, and certificates are created, held and transferred in the REC Registry.

The definition has four moving parts. A creator (the system owner, or an installer or trader holding an assignment) lodges a claim. A regulator checks and registers the certificates. A buyer, which is a trader or a liable entity, pays for them. And a surrender step at the end, where retailers hand the certificates back to meet their annual target.

In practice

The definition matters most at the quote stage. A system’s STC entitlement depends on kilowatts installed, the postcode zone and the deeming period for the year of installation. For small-scale solar installed in 2026 the deeming period is five years, so the certificate count for a given system is higher than it will be in 2027, when it drops to four. The scheme ends on 31 December 2030.

Batteries are calculated differently, from usable capacity and a yearly STC factor. See STC factor.

Common confusion

“STC” gets used for three different things in a single conversation: the certificate itself, the discount on the customer’s invoice, and the payment an installer receives from a trader. They are linked but not identical. The discount is what the customer sees. The payment is what the installer banks, and it moves with the market. The explainer on what an STC is worth in 2026 walks through the difference.

A second trap is the unit. One STC is one megawatt-hour, not one kilowatt-hour, which is why a 6.6 kW system produces dozens of certificates rather than thousands.

For the broader vocabulary, see the certificate trading glossary. To see how selling works end to end, start at how it works.