How STC Rebates Are Calculated For Solar Systems in 2024

If you’re getting quotes for solar on the Gold Coast, Brisbane, or Adelaide, you’ve probably noticed that most installers advertise prices after the STC rebate has been applied. But what exactly are STCs, and how does the calculation work for your specific system?

After installing over 13,500 solar systems across Queensland and South Australia, CJN Solar owner Craig Cannon has seen plenty of confusion around this topic. Let’s break down exactly how the STC rebate is calculated, so you know what you’re actually paying for.

What Are STCs and Why Do They Matter?

Small-scale Technology Certificates (STCs) are federal government incentives designed to make solar more affordable for Australian households and businesses. They’re part of the Renewable Energy Target scheme and effectively work as an upfront rebate on your solar system.

Here’s the thing most people don’t realise: STCs aren’t technically a rebate at all. They’re tradeable certificates that your solar installer creates on your behalf when they install your system. The installer then sells these certificates and passes the value back to you as a discount on your system price.

That’s why when you look at solar packages and pricing, you’ll see the price listed after the STC value has been deducted. It’s already factored in.

The Four Key Factors in STC Calculation

The number of STCs your solar system generates depends on four main factors:

1. System Size (in Kilowatts)

Larger systems create more STCs. A 6.6kW system will generate more certificates than a 3.3kW system because it has greater renewable energy generation capacity. This is based on the combined wattage of your solar panels, not your inverter size.

2. Your Location (Zone Rating)

Australia is divided into zones based on how much solar radiation each area receives. The more sunshine, the more renewable energy your system produces, and the more STCs you’re entitled to.

Good news for CJN Solar customers: both Queensland and South Australia are in favourable zones. The Gold Coast, Brisbane, and SEQ are in Zone 3, while Adelaide is in Zone 4. These zones attract a healthy number of STCs compared to cooler southern areas.

3. The Deeming Period

STCs are calculated based on how many years your system is deemed to generate renewable energy until 2030 (when the current scheme ends). This is called the deeming period.

Here’s the catch: every year that passes, the deeming period gets shorter, which means fewer STCs. In 2024, systems are deemed to generate renewable energy for fewer years than systems installed in 2023. That’s why the STC rebate decreases each year, and why it pays to install solar sooner rather than later.

4. Panel Efficiency and Ratings

The Clean Energy Regulator uses specific ratings for different panel models. Premium panels like the ones CJN Solar installs from brands like Hinen, TCL, Tongwei, Jinko, and Trina are all approved for STC creation under the scheme.

The Actual STC Calculation Formula

Want to know the exact formula? Here it is:

STCs = (System size in kW × Zone rating × Deeming period in years) ÷ 1

Let’s use a real example: a 6.6kW system installed on the Gold Coast in 2024.

• System size: 6.6kW
• Zone 3 rating: 1.382
• Deeming period until 2030: approximately 6 years
• Calculation: 6.6 × 1.382 × 6 = approximately 54.7 STCs (rounded to 54)

Each STC has a market value that fluctuates, but typically sits around $36-$40. So for this system: 54 STCs × $38 (average) = approximately $2,052 in upfront savings.

For a larger 10kW system in Adelaide (Zone 4, rating 1.622), the numbers look even better:

• 10 × 1.622 × 6 = approximately 97 STCs
• 97 × $38 = roughly $3,686 in savings

This is why our pricing already shows you the cost after STCs have been applied — it’s what you’ll actually pay out of pocket.

What About Battery Systems?

Here’s where it gets a bit different. STCs only apply to the solar panel component of your system, not the battery storage itself. However, when you add a solar battery like Sigenergy to your system, the solar panels that charge it still qualify for STCs.

Every CJN Solar battery installation also includes integration with Powwow’s Virtual Power Plant (VPP), which can provide additional rebates and ongoing bill credits in both Queensland and South Australia. These are separate from STCs and worth exploring when you’re looking at battery options.

Does My Installer Handle the STC Process?

Yes — and this is important. Reputable installers like CJN Solar handle the entire STC creation and redemption process on your behalf. We register the certificates, sell them, and apply the discount directly to your invoice.

You don’t need to do anything except sign the paperwork assigning the STCs to us. This is standard practice across the industry, but it’s worth confirming with any installer you’re considering.

With Craig Cannon’s 15 years of experience and over 13,500 systems installed, CJN Solar has processed tens of thousands of STC certificates for customers across the Gold Coast, Brisbane, and Adelaide. It’s a seamless part of our installation process.

Why the STC Rebate Is Decreasing

The elephant in the room: STCs are worth less each year because the deeming period shrinks as we get closer to 2030. In 2024, you’re getting roughly 6 years of deemed generation. In 2025, it’ll be 5 years. In 2030, the scheme ends entirely (unless the federal government extends it).

The math is simple: fewer years = fewer STCs = smaller rebate = higher upfront cost for the same system.

This is why waiting to install solar actually costs you money twice: once through the reducing rebate, and again through the ongoing electricity bills you’re still paying.

Get Your Exact STC Value With a Free Quote

Every solar system is different, and your exact STC rebate depends on your specific system size, location, and installation date. Want to know exactly what rebate you’ll receive and what your final out-of-pocket cost will be?

CJN Solar provides transparent, no-obligation quotes that break down all the numbers — including your STC value. Whether you’re in the Gold Coast, Brisbane, or Adelaide, we’ll calculate your exact rebate and show you what you’ll actually pay.

Call 1300 969 574 or get a free quote online today. You can also use our solar calculator to get an instant estimate of what system size suits your home and what STCs you’ll receive.

With our 4.3-star Google rating from 42 reviews and Craig’s 15 years of experience, you’re in good hands. Let’s get you saving on power bills with a system that’s properly sized, properly priced, and backed by Australia’s STC rebate while it’s still available.