Commercial Solar SRES 1 MW Expansion: Installer Guide

From 1 October 2026, a commercial solar system above 100 kW and up to 1 MW can create STCs. That moves a block of work from the large-scale scheme, where value trickled in as LGCs at $6 to $9, to the small-scale scheme, where it arrives upfront at about $38 to $40 per certificate. For a commercial installer, it changes quoting, margins, evidence and cash flow all at once.

This is the working guide. If you want the business owner’s view, see what the 100 kW to 1 MW expansion means. The pillar page is mid-scale solar STCs. The rules are in the amended Renewable Energy (Electricity) Regulations, and the Clean Energy Regulator (CER) says applications open mid to late November 2026. Details can still change, so check the CER’s mid-scale page before you lodge.

The rule in one paragraph

Solar PV systems of more than 100 kW and up to 1 MW installed from 1 October 2026 create STCs under the Small-scale Renewable Energy Scheme, using the same formula as small-scale solar with a fixed five-year deeming period: kW x zone rating x 5. Below 100 kW, nothing changes: five years for 2026 installs, four for 2027. Above 1 MW, systems remain power stations creating LGCs.

What it is worth, by size

Zone 4 (Melbourne, Hobart) systems earn about 14% less per kW at a rating of 1.185 against 1.382. Zone 2 (Darwin) is 1.536 and zone 1 (Alice Springs) 1.622. A 500 kW system in Melbourne creates 2,962 STCs, about $112,600 at $38. Use the STC calculator to check any postcode.

Eligibility checklist

Use this before you quote.

1. Installation date on or after 1 October 2026.
2. Size above 100 kW and up to 1 MW. Confirm how the CER measures capacity for the limit.
3. SAA accreditation for the people who design and install, as required.
4. Approved products. Panels and inverters on the Clean Energy Council lists on the installation date.
5. Electrical safety. Compliance with state and territory rules, which determines the installation date.
6. Network connection. Agreement in place for the system as built.
7. Planning and approvals. Local, state and federal requirements met.
8. Ownership. A signed assignment from the system owner if you will lodge.

Whether a 250 MWh annual output limit, which applied to small-scale systems up to 100 kW, applies to the mid-scale category should be checked in the CER guidance. We would not assume either way.

Quoting

Show the STC line. State the number of STCs, the assumed price and the date the discount depends on. The claim will not open until mid to late November, so be clear that the figure is an estimate until certificates are created and sold.

Quote the options. Run a 99 kW option and a larger option. In zone 3, 99 kW creates 684 STCs in 2026 ($25,992) and 250 kW creates 1,727 ($65,626). If the roof and load support 250 kW, the old rationale for 99 kW has gone.

Be careful with timing. A job installed on 20 September is outside the expansion. One installed on 1 October is inside it. The installation date follows the state electrical safety rules, so confirm what date applies for compliance.

The gap between 1 October and mid to late November

Systems installed in October cannot have certificates created until the CER opens applications. In that gap:

1. Keep evidence at the highest standard. Photos with geotags and timestamps, serial numbers, SAA records, approvals and commissioning data. Large claims draw large scrutiny.
2. Record the installation date and the compliance date in the job file.
3. Plan the cash. The discount on the quote is yours to fund until claims are created and paid. On three 250 kW jobs in October, that is about $197,000 of certificates waiting.
4. Agree the lodging arrangement with your trader in advance. Confirm they can accept and pre-check a claim of that size.

See the installer cash flow guide.

Evidence for a large claim

The mid-scale evidence set follows the small-scale pattern, scaled up. Expect to document:

• the array layout and string configuration, with photos by section;
• the serial numbers of panels and inverters, matched to the approved lists;
• inverter and protection settings;
• the single line diagram and network approval;
• the commissioning report;
• the assignment form and owner identity;
• the invoice with the STC discount shown.

Panel serial capture on a 500 kW array means 1,000 or more panels. Plan how the crew will record them, such as scanning pallet labels on delivery and tying them to the string map. See STC photo requirements and how STC audits work.

Choosing a trader for large claims

Ask each trader:

1. Have you handled claims over $50,000? What is your pre-check process?
2. How is the rate locked, and when does the clock start?
3. Is there any cap on claim size or any extra review time?
4. What happens if a claim is queried by the CER?
5. Can I split a large claim across several lodgements, and what are the terms?

Settlement matters more at this size. On a $65,626 claim, 20 business days of waiting at 10% costs about $500 in financing, against under $20 on a 1-day term, and the exposure to a single counterparty is far larger. See the trading guide and choosing a trader. At Energy Merchants, the compliance desk reviews every claim before lodgement, including large ones. Rates are on pricing.

What about LGCs?

Existing power stations above 100 kW keep their accreditation and keep creating LGCs. New systems above 1 MW take the LGC route, at about $8 in late September 2026. See how to accredit a power station, how to sell LGCs and LGC vs STC.

Questions crews ask

Can I still design to 99 kW? You can, but only if the load and roof call for it. The old reason for it, keeping the system under the STC limit, no longer applies. See the 100 kW limit answer for the earlier rule.

What if the CER’s guidance differs from this page? The CER wins. Treat our summary as orientation and read its mid-scale page before you quote.

Do I need to accredit a power station for a 400 kW job? Not for STCs. Power station accreditation is for the LGC route, which now covers systems above 1 MW and existing stations. See LGC vs STC.

Who owns the certificates on a PPA job? Normally the provider, as the system owner. Confirm it in the contract. See commercial solar PPAs explained.

Do panel serials really need to be scanned one by one? The approved list check and the evidence rules point that way, so plan for it. Capturing serials on delivery is much faster than climbing back onto a roof.

What to do next

1. Build a mid-scale quote template with the STC line, installation date clause and options at 99 kW and larger.
2. Confirm SAA accreditation for your designers and installers.
3. Set up an evidence routine for large arrays, including panel serials.
4. Ask your trader about large-claim handling before the first job.
5. See how it works and start trading to line up your first mid-scale claim.