For years, 100 kW was a hard line. A system at 99 kW earned upfront STCs. A system at 105 kW did not, and had to create LGCs year by year after getting accredited as a power station. That left a “missing middle” of commercial rooftops that were punished for being slightly bigger.
What changed
The Small-scale Renewable Energy Scheme now extends to mid-scale solar. At the time of writing:
- Below 100 kW: unchanged, STCs with the declining small-scale deeming period (5 years for 2026, 4 for 2027).
- Above 100 kW and up to 1 MW, installed from 1 October 2026: STCs with a fixed five-year deeming period.
- Above 1 MW: remains in the large-scale scheme and creates LGCs.
The Renewable Energy (Electricity) Regulations were amended in 2026, and the Clean Energy Regulator has said applications open in mid to late November 2026. See the mid-scale solar STC page for the full explanation.
What a just-over-100 kW system earns
The STC formula uses system size, a zone rating and the deeming period. A rough example for 105 kW in zone 3 (Sydney, Brisbane, Perth and others at 1.382): 105 x 1.382 x 5 = about 725 STCs. At STC spot of roughly $38 to $40, that is around $27,500 to $29,000 upfront, at the time of writing. Check the zone with the STC calculator; the final mid-scale rules may add detail, so confirm with the CER.
Compare that with the LGC route: the same system might generate about 150 MWh a year, so about 150 LGCs, which at $6 to $9 (September 2026 range) is roughly $900 to $1,350 a year. The upfront STC value is much larger. See LGC revenue for a 200 kW system.
Why a fixed deeming period matters
Small-scale deeming falls by one year each January until 2030. A mid-scale system gets a fixed five years, so a 2027 mid-scale installation does not suffer the January step-down that small systems do. Say that to commercial customers carefully, since the policy is new and details can be refined.
What this means for installers and owners
If you are quoting a system over 100 kW, build the STC discount into the quote with a clear note that it depends on CER processing. Installers should ask their trader how mid-scale claims are handled before the November opening; Energy Merchants can walk you through its approach via the partner program or start trading, and the pricing page lists the published rates. For LGC fundamentals read LGC vs STC and the commercial solar hub.