Australia’s Renewable Energy Target has two certificate types, and mixing them up is easy. The simplest way to remember it is by size and timing.
The comparison
| STC | LGC | |
|---|---|---|
| Scheme | Small-scale Renewable Energy Scheme | Large-scale Renewable Energy Target |
| System | Up to 100 kW, solar up to 1 MW from 1 October 2026, plus hot water, heat pumps, batteries | Accredited power stations, including solar above 1 MW and older commercial solar above 100 kW |
| Created | Upfront, for deemed generation over the deeming period | After generation, for actual output |
| Unit | One per MWh deemed | One per MWh generated |
| Price | $38 to $40 at the time of writing, with a $40 clearing house ceiling | Roughly $6 to $9 in September 2026 spot, no ceiling |
| Buyers | Liable entities through traders | Liable entities through traders and brokers |
What it means in practice
For a small rooftop system, STCs arrive as a discount at the point of sale. The owner gets the value upfront, and the installer sells the certificates. For an accredited commercial system, LGCs arrive as the system produces, so the value builds over years and depends on metering, reporting and registry steps.
Why the price gap is so large
The STC price is anchored by the clearing house at $40, which keeps buyers and sellers close to that figure. LGCs have no such backstop, so the price reflects open market supply and demand. Also, an STC for a rooftop system covers several years of deemed generation, while an LGC is one MWh of actual output.
Where the line sits
Size and install date separate the two: up to 100 kW (with an annual generation cap of 250 MWh), or up to 1 MW from 1 October 2026 with a fixed five-year deeming period, is STC territory. See mid-scale solar STCs and commercial solar and the 100 kW limit.
From the desk: the maths on a 99 kW system and a 101 kW system can look very different. Run both before you finalise a design.
An example of the trade-off
A 99 kW system in zone 3 earns 684 STCs in 2026, worth about $26,000 to $27,000 upfront at current prices. A 120 kW system would instead create LGCs over time, with a lower price per certificate and accreditation to manage, but more energy generated. Neither is wrong. They suit different clients, so model both.
What this means for you
If you install small systems, STCs are your bread and butter. See STC trading and pricing. If a commercial job crosses the line, read what is an LGC and the resources hub first.