Rebates & Incentives

STCs and Large-Scale Certificates: Commercial Solar Incentives

Guide · Commercial solar & battery · ~5 min read

If you're weighing up commercial solar, the certificate scheme you fall under shapes how your upfront cost and ongoing returns stack up. Here's how STCs and LGCs actually work for a business, without the jargon.

What Are STCs and LGCs?

Australia's Renewable Energy Target splits solar incentives into two schemes based on system size. Both create tradeable certificates, but they work in very different ways.

Small-scale Technology Certificates (STCs) apply to smaller systems and are usually claimed as an upfront discount off your install price. Large-scale Generation Certificates (LGCs) apply to bigger systems and are earned over time based on the power you actually generate.

• STCs: a one-off upfront benefit, typically assigned to your installer to reduce the sticker price.
• LGCs: created annually as your system produces electricity, then sold or traded.
• The size of your system decides which path you're on.

Where the Line Sits for Commercial Systems

The general threshold between the two schemes sits at 100kW. Systems at or below that size usually fall under STCs, and larger systems typically register under the LGC scheme.

This matters because many commercial rooftops sit right around that decision point. A warehouse, factory or vineyard shed might be sized either way depending on your roof space, your load profile and your goals. Where your system lands changes how the incentive flows to you.

How STCs Work in Practice

For most small-to-mid commercial systems, STCs are the simplest route. The certificates are calculated based on your system's size and location, then assigned to your installer, who passes the value back as a discount on the quoted price.

You don't have to trade anything yourself or wait for returns to build up. The benefit is baked into your upfront cost, which keeps the process clean for a business owner who just wants the system on the roof and working.

How LGCs Work for Larger Installs

Once you move past the small-scale threshold, you're in LGC territory. Instead of an upfront discount, your system generates certificates as it produces power, which you can sell into the market.

This is an ongoing revenue stream rather than a one-off benefit, and it requires registration and metering to track generation. For larger rooftops like our 415kW installation at DB Santasalo in Bulli, understanding this side of the scheme is part of getting the numbers right.

• Certificates accrue over the life of the system as it generates.
• Requires registration and accredited metering.
• Suits businesses with the scale and roof space to justify a larger array.

Choosing the Right Path for Your Site

There's no single right answer. The best fit depends on your available roof, your electricity load, your tariff structure and whether you're pairing solar with battery storage and AI energy arbitrage.

In some cases a system sized just under the threshold makes sense; in others, going larger and earning LGCs stacks up better over time. Adding a battery that charges when power is cheap and discharges when it's dear can change the whole equation, so it's worth modelling properly before committing.

Get the Real Numbers for Your Business

Certificate values, eligibility and the size that suits your site all come down to specifics that a generic guide can't pin down. The figures that actually apply to you come from looking at your roof, your bills and your load profile.

As a CEC and SAA accredited installer working Australia-wide with an in-house team, ATI can walk you through which scheme fits and what it means for your bottom line. If you'd like the real numbers for your site, a short site review is the place to start.

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