From 1 October 2026, commercial and industrial solar systems between 100kW and 1MW can claim the same upfront federal rebate that smaller systems have had for years. For any business that capped its system at 99kW, or shelved a bigger one because the numbers didn't work, it's time to run them again.

Here's what changed, what it's worth, and what to check before you commit.

What changed with the STC's Cover for Commercial Solar in Adelaide?

The federal regulations were amended to lift the size limit for solar under the Small-scale Renewable Energy Scheme (SRES) from 100kW to 1MW. The Clean Energy Regulator calls the new band "mid-scale solar".

Small-scale Technology Certificates (STCs) are the certificates behind what most people call the solar rebate. Your installer claims them and takes their value off your price upfront.

Before 1 October 2026 > After 1 October 2026

• Largest system eligible for STCs increased from 100kW to 1MW
• Incentive for 100kW to 1MW was for large-scale certificates, earned year by year on actual generation. Going forward STCs are claimed once, upfront
• Previously power station accreditation, metering and annual reporting were required, now it's the same process as a small system
• Now the deeming period is fixed at 5 years, before this wasn't applicdable.

That old cliff at 100kW is why so many commercial roofs carry a 99kW system with half the roof left empty. The system was sized to the rebate, not to the building.

What is a 500kW commercial system in Adelaide worth? 

A 500kW system in Adelaide now attracts roughly $120,000 in upfront STC value. Before 1 October, the upfront figure for that system was zero.

The number of STCs is system size (kW) × your zone rating × the 5-year deeming period.

Here's how that plays out.

• A 300kW Commercial System creates 2073 STC's which has an approximate value of $73,000 upfront
• A 500kW Commercial System creates 3455 STC's which has an approximate value of $121,000 upfront
• A 1MW Commercial System creates 6910 STC's which has an approximate value of $242,000 upfront

These are estimates, not quotes. They assume an Adelaide zone rating of 1.382 and an STC price of $35. The STC price moves with the market and your location changes the zone rating. The Regulator has a mid-scale solar STC calculator if you want to check your own site.

The bigger shift is timing. Under the old path, the incentive trickled in over years and depended on what the system generated. Now it comes off the price on day one, which shortens payback and makes finance simpler.

Who does the STC change to Commercial Solar help the most?

Any site that uses a lot of power during the day and has the roof or land to match.

• Manufacturers and workshops running machinery through daylight hours.
• Cold storage, wineries and food processors with heavy refrigeration loads.
• Warehouses and logistics sites with big roofs and growing EV or forklift charging.
• Farms and packing sheds with pumps, cooling and seasonal peaks.
• Schools, aged care and shopping centres with steady daytime demand.
• Sites already at 99kW that have roof left over and bills that still hurt.

It might not be right for you. If most of your usage is overnight, or your network connection limits how much you can export, a bigger array may not pay its way without a battery. That's a design question, and it's the first one we'd ask.

Key things to know before you size up if the STC is right for you

The rule is live, but there's fine print worth knowing.

1. STC applications open later. The system must be installed from 1 October 2026 to qualify. The Regulator won't accept mid-scale STC applications until mid to late November 2026. Ask your installer how they're pricing that gap.
2. There's no rush. The deeming period for 100kW to 1MW is fixed at 5 years. It doesn't step down each year like it does for smaller systems. The scheme is scheduled to end in 2030, so you have time to design it properly.
3. You choose one certificate path. If you claim STCs, you can't create Renewable Electricity Guarantee of Origin (REGO) certificates for that system during the deeming period. If your business reports on renewable energy use, talk that through first.
4. Extensions are still being clarified. The Regulator has said more guidance is coming on existing systems, extensions and upgrades. If you're adding to an existing array, get the eligibility confirmed in writing before you sign.
5. Grid approval takes longer than the rebate. Systems this size need a network connection assessment, and export limits are common. Start that conversation early.
6. Your installer matters more at this size. STCs can only be claimed on systems designed and installed by accredited people using approved products. A 500kW job is an engineering project. Check they've delivered commercial work before.

Our honest take on the change

This is the biggest change to commercial solar in years. It doesn't make every large system a good idea. It means the system can finally be sized to your building and your bills, not to a rebate threshold.

If you ruled out solar above 100kW, or you're sitting on a 99kW system with roof to spare, we'll run the numbers on your site and tell you straight whether it stacks up. Free consultation, no obligation.

Get in touch

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Sources

• Mid-scale solar, Clean Energy Regulator, last updated 22 September 2026
• Renewable Energy (Electricity) Amendment (Mid-scale Solar) Regulations 2026, Federal Register of Legislation

Dollar figures are our own estimates from the STC formula and are approximate.