The STC market is unusual because demand is manufactured by regulation and supply is created by household decisions. Understanding both sides explains most price moves.
Supply: how many certificates get created
Supply comes from small-scale installations. In 2024 about 34.1 million STCs were created, and in 2025 the figure was 25.0 million, according to the Clean Energy Regulator’s quarterly reports. Those totals exclude certificates created for batteries under the Cheaper Home Batteries Program, which are bought by the government. We go through the numbers in how many STCs are created each year.
Supply rises with installation volumes, falling panel prices and incentives, and falls as the deeming period shortens. Each year’s install gets fewer certificates than the last, which is also why the solar rebate drops every year.
Demand: what retailers must surrender
Demand comes from the small-scale technology percentage, the STP. Each year the regulator calculates a percentage of liable electricity that retailers must cover with STCs. In 2026 it is 11.67 per cent, based on an estimate of 24.1 million certificates to be created. Our page on what the STP is explains the calculation.
Because the STP is designed to match forecast supply, demand and supply are close to balanced on paper. Price moves occur when the actual creation differs from the forecast. More certificates than expected makes the Clearing House queue longer and widens the gap below $40. Fewer makes buyers compete for certificates.
The ceiling and the queue
Whatever supply and demand do, the $40 Clearing House price caps the upside, as covered in why the STC price is capped. The depth of the transfer list sets how far below $40 sellers must go for speed. See surplus and deficit at the Clearing House.
Policy shocks
Rule changes move the market faster than anything else. Batteries joined the STC system on 1 July 2025. From 1 October 2026, solar above 100 kW and up to 1 MW also creates STCs, a change we describe in mid-scale solar STCs. New categories add supply, though how the STP forecast absorbs them is for the regulator’s modelling. Treat commentary on their price effect as opinion until the numbers are in.
Timing and seasonality
Installation volumes vary through the year, and rush periods before rebate steps, such as 1 January each year, raise creation. Lodgement lags then bring the volume into the registry weeks later. See how the deeming period change affects January.
What this means for installers
You cannot control supply, demand or the ceiling, but you can control when you lodge and with whom. A trader with a daily published, locked rate removes the guesswork. See our pricing page and how STC trading works.