Both certificates come from the Renewable Energy Target, and both are bought by electricity retailers. What differs is the size of system, how the certificate is counted and when it is created.
Side by side
| STC | LGC | |
|---|---|---|
| Scheme | Small-scale Renewable Energy Scheme | Large-scale Renewable Energy Target |
| Applies to | Rooftop solar up to 100 kW, mid-scale solar up to 1 MW from 1 October 2026, small wind, hydro, batteries, hot water and heat pumps | Accredited power stations, including solar over 1 MW and older solar over 100 kW |
| Counted | Expected output over a deeming period | Actual MWh generated |
| Timing | Upfront, at installation | Over the life of the system |
| Price | About $38 to $40 spot, clearing house at $40 | About $6 to $9 in September 2026 spot, floating |
| Who creates | Installer, agent or owner | The power station owner or an agent |
Why the split exists
Small systems are spread across millions of roofs, so certificates are created in advance based on deemed output. That keeps the paperwork light. A large power station has meters, so generation is counted for real, and certificates are issued as it happens.
What changes for each audience
A homeowner sees STCs as a discount on a rooftop system, and will never deal with an LGC. A business with a 150 kW roof deals with LGCs and has no upfront discount. An installer works with STCs on small jobs, and may facilitate LGC accreditation for commercial work.
Who buys each
Both certificates are bought mainly by electricity retailers, who must surrender enough of them each year to meet their obligations. STCs are bought through traders or the clearing house, while LGCs trade between power station owners, brokers and retailers, often through longer contracts. For an installer, the practical point is that the STC market is deep and quick, while the LGC market tends to involve specialist agents and more negotiation. That is one reason many commercial customers use an agent.
What this means for you
Start with the STC explainer if you are a homeowner. Installers quoting commercial work should read mid-scale solar STCs, LGCs for commercial solar above 100 kW and how to create LGCs. Our STC trading page, the pricing page and the glossary have more.