STCs Are Expanding to 1 MW: What It Means for Commercial Solar

In short: Small-scale Technology Certificates (STCs) now extend from the old 100 kW cap up to 1 MW of solar. The amending regulations were registered on 17 September 2026 and apply to systems installed from 1 October 2026, at a fixed 5-year deeming period through to 2030. That is worth roughly $272 per kilowatt upfront at today’s certificate prices – about $68,000 off a 250 kW system. The catch to watch is the ceiling: eligibility is tested on the site’s total capacity, so related arrays and an accredited power station next door count towards the 1 MW limit, and only the first megawatt carries the upfront certificates.

What Was Announced

Climate Change and Energy Minister Chris Bowen used a National Press Club address on 5 August 2026 to announce an expansion of the Small-scale Renewable Energy Scheme (SRES). Solar PV systems with a total onsite capacity between 100 kW and 1 MW will be able to create upfront, deemed STCs instead of registering as a power station and earning Large-scale Generation Certificates (LGCs) year by year. The government’s framing is the “missing middle”: Australia has roughly 22 GW of residential rooftop solar and only about 5.6 GW of commercial rooftop, against an estimated 80 GW-plus of commercial roof space that could host panels.

The start date is 1 October 2026, applying to systems installed from that date: the testing and commissioning date on the certificate of electrical compliance, not when the project was designed, procured or built. The announcement was qualified “subject to regulations being made”; those regulations, the Renewable Energy (Electricity) Amendment (Mid-scale Solar) Regulations 2026, were registered on 17 September 2026 and commence on 1 October 2026. One practical wrinkle remains: the Clean Energy Regulator expects STC applications for mid-scale systems to open in mid-to-late November 2026, so an October install creates its certificates but cannot lodge for them straight away.

What It Is Worth

The government’s own worked examples put the upfront discount at about 20% of installed cost. They also scale exactly linearly, which tells us something useful: the numbers match the existing STC formula (system size × zone rating × deeming years × certificate price) applied unchanged above 100 kW, with no taper and no cap.

Zone matters: the deeming calculation uses a postcode zone rating between 1.185 and 1.622, so the same system is worth more in Brisbane than in Hobart. The examples above use zone 3 (1.382), which covers most of the east-coast capitals. Certificate price is the spot STC price, which has sat just under the $40 clearing house cap all year.

For context on why installers care: the 100 kW line is the reason the 99 kW system exists. Thousands of commercial roofs got a system sized to duck under the cap, because crossing it meant losing the upfront rebate, registering as a power station, adding revenue metering, and collecting LGCs one year at a time against a price outlook that weakens toward 2030. From 1 October, a site that needs 300 kW can be quoted as 300 kW.

How the Maths Works Above 100 kW

Nothing announced changes the STC formula itself. Certificates are still deemed generation: system capacity in kW, times the postcode zone rating, times the deeming period in years, rounded down. A 2026 install gets 5 deeming years (2026 through 2030, when the SRES ends).

The deeming period for later installs was the big open question, and the registered regulations settle it. Below 100 kW the period still steps down every calendar year: a 2027 install gets 4 years, 2028 gets 3, and so on. Mid-scale systems do not step down. The instrument gives them certificates “within 12 months of installation and for the period of 5 years”, a flat five years for every install year through to the end of 2030. For a 2028 install that is five years instead of three, which is worth more than the size change on some projects.

What the Regulations Settle

• The deeming design for 2027 and beyond: a fixed five years, as above. A mid-scale project no longer loses certificate value by slipping into a later install year.
• How the 1 MW limit is measured. The test adds the device’s kW rating to any related solar devices and any related accredited power stations, at the time of installation. Related reaches arrays on the same site or on adjoining sites in the same area, so a neighbouring power station can eat into the megawatt an otherwise ordinary 400 kW job was counting on.
• The 250 MWh annual output limit. It does not apply to mid-scale devices, and the amended definition keeps it only for small-scale systems installed before 1 October 2026. An 850 kW system generating around 1,170 MWh is not caught by it.
• Whether new mid-scale systems can still choose LGCs. No. A system cannot create both for the same capacity, and the Clean Energy Regulator has said support for new mid-scale installations is intended through the SRES rather than the LRET. Existing accredited power stations keep their LGC arrangements, and need separate metering to keep creating LGCs beside a new mid-scale system.
• Extra compliance requirements. Mid-scale units carry three new conditions: all Commonwealth government requirements met for the installation, written evidence to the Regulator that every Commonwealth, state, territory and local planning and approval requirement has been met (network connection approvals included), and a matching written statement from the installer. Accredited product and installer requirements continue. The accredited-designer requirement does not apply to mid-scale units, and AS 4777 can be recorded as not applicable where it does not cover the inverter.

What Does Not Change

Systems under 100 kW are untouched; the existing STC arrangements simply continue. Systems above 1 MW stay under the Large-scale Renewable Energy Target and keep earning LGCs. Batteries are not part of this change either way: they sit under the separate Cheaper Home Batteries program, currently 6.8 STCs per usable kWh with its own step-down schedule. And Victorian VEECs keep their own rules under the VEU program. If you want the current state of every scheme in one place, the incentives hub stays updated as the rules move.

The Date Is the Whole Test

A 300 kW system installed in September earns LGCs; the same system installed in October earns around $80,000 of upfront STCs. There is no transitional relief across that line, and none is coming: eligibility turns on the install date, not on when construction or procurement started, so a project can be designed, procured and built before October and still qualify as long as it is commissioned after it. The Clean Energy Regulator asks that you keep the records to prove it, including the compliance certificate, network connection approvals, planning approvals and commissioning evidence. One timing quirk to price in: STC applications for mid-scale systems are not expected to open until mid-to-late November 2026, so an early October install creates its certificates before there is anywhere to lodge them.

October Is Half the Story

A month before the STC change, NSW switches on its first commercial battery incentives: PDRS activities BESS4 (business batteries, 20–200 kWh) and BESS5 (C&I batteries up to 30 MWh) start 1 September 2026, worth tens of thousands of dollars on a typical business battery. A commercial site quoted in spring 2026 can stack upfront STCs on the solar with PRCs on the battery, which did not exist as a combination three months ago. We covered the battery side in the NSW battery rebate guide.

Model It in Amperage Today

Amperage prices the mid-scale rules by default, and keeps the choice on the project so you can turn them off. Set a project’s install date to 1 October 2026 or later and the 1 MW expansion applies on the project’s STC row: any system between 100 kW and 1 MW is quoted with whole-system STCs at the fixed five-year deeming, with the LGC stream removed to match. Push the site’s total past 1 MW and the excess goes back to the LGC stream, the same split the 100 kW rules have always used. The engine was re-verified against the registered instrument on 18 September 2026. The STC calculator and LGC calculator show the mid-scale band alongside the legacy rules, or you can book a demo to see a 100 kW–1 MW quote come together.

The Short Version

STCs extend from 100 kW to 1 MW for solar installed from 1 October 2026, worth roughly $272/kW upfront at current prices, on a fixed five-year deeming period that does not taper before the scheme ends in 2030. The regulations registered on 17 September 2026. Systems already accredited for LGCs stay where they are, and their capacity counts towards the 1 MW test for anything new on the same or an adjoining site. If you quote commercial solar, the 99 kW era is over; check the maths on the real system size, and check the site’s total capacity before you promise anyone a certificate.

Commercial solar calculator – estimate size and incentive value →

Solar payback calculator – see how the expanded STC changes your payback →