Mid-scale solar

Written and checked by the Energy Merchants desk · Reviewed 3 October 2026

Mid-scale solar is a loose industry term for commercial systems that sit between household rooftop solar and utility solar farms. In certificate terms the band is now defined: above 100 kW and up to 1 MW. At or below 100 kW, a solar system is small-scale and creates STCs at installation. From 1 October 2026, systems in the mid-scale band create STCs too, with a fixed five-year deeming period. Above 1 MW the system is treated as a power station. The full rules are on the mid-scale solar STCs page.

What changed at 100 kW

• Certificate type. Before 1 October 2026, a system above 100 kW created LGCs, not STCs. From that date, up to 1 MW, it creates STCs. Above 1 MW it still creates LGCs.
• Timing. STCs are created up front for five years of deemed output. LGCs are created after the electricity is generated.
• Claims. The Clean Energy Regulator says applications for mid-scale STCs open mid to late November 2026.
• Value. STCs are about $38 to $40 at the time of writing. LGC spot was roughly $6 to $9 in September 2026.

See LGC definition for the full comparison.

In practice

The old cut-off shaped design decisions: a roof that could take 120 kW often got a 99 kW system to capture STCs up front. For installs from 1 October 2026 that trade-off is gone. Size the system to the site’s usage and the customer’s cash position, then show the certificate value at that size.

Worked example. A 99 kW system in zone 3 installed in 2026 creates 99 x 1.382 x 5 = 684 STCs (rounded down), worth roughly $26,000 to $27,400 at current spot, received at the start. A 120 kW system installed from 1 October 2026 creates 120 x 1.382 x 5 = 829 STCs, worth roughly $31,500 to $33,200.

Common confusion

Mid-scale is sometimes used for a system that is large but still under 100 kW. For certificates, that is still small-scale. The band applies to the system’s capacity as registered. Splitting a large site into several systems to stay under a limit is something the regulator looks at closely, so take advice before designing around it.

See the STC trading page for the small-scale route and start trading to discuss a larger job. The certificate trading glossary has other terms.