The STC deeming period to 2030

What deeming means

A small-scale system does not earn certificates year by year. The scheme deems how much renewable electricity it will generate between the install and the end of the scheme, and issues one STC for each megawatt hour of that, up front. That is why a system owner can take the value as a discount on the day of the sale, and why a trader can pay for the certificates straight away.

The scheme ends with 2030, so each year a new system has one year less of generation to be deemed. For panels, the deeming period is the number of years in the sum: kW x zone rating x deeming years, rounded down. Fewer years means fewer certificates for the same panels on the same roof.

Panel deeming years to 2030

For systems up to 100 kW the deeming period falls by one year every 1 January. The regulator's table runs from 6 years for a 2025 install down to 1 year for a 2030 install:

The zone is the other half of the sum, and it follows the install postcode: STC zones and ratings.

The exception: mid-scale solar

From 1 October 2026 the scheme also covers solar systems over 100 kW and up to 1 MW. Those systems get a fixed five-year deeming period whatever the install year, so a mid-scale system installed in 2030 still gets five years where a system up to 100 kW gets 1. Mid-scale solar STCs has the rules and the dates.

What a January costs on a job

The certificates for three common sizes, by install year, in the two zones where most systems go in. Dollar figures use $41 per STC, what we pay on a home system as at 3 November 2026.

Zone 3: Sydney, Brisbane, Perth, Adelaide and Canberra

Zone 4: Melbourne and Hobart

The drop from a 2026 install to a 2027 install

$41 is above the $40 clearing house price, and the regulator advises caution with prices above that cap, so check us as you would any trader. What to check in any trader.

For another zone, size or date, the calculator works it out from the postcode.

Which date counts

The deeming period follows the installation date, not the date the certificates are created. Certificates must be created within 12 months of the install, so a system installed in December and claimed in February still gets December's years. It does not work the other way: a system installed in January gets January's years, however early the contract was signed.

The install date on the claim has to be the real one. The regulator audits claims and can fail one whose paperwork does not match what happened on site.

What it means for quoting

• A quote written in November or December for a job that will be installed in January should use January's deeming years. If it uses this year's, the difference comes out of your margin, not the customer's.
• Put the install month and the STC figure on the quote, and say the discount depends on the system being installed by that date.
• Watch the install calendar in late December. A job that slips a week across the new year loses 8 to 19 certificates on the sizes above.
• The price per STC moves separately from the number of STCs. We publish ours with its date: STC price.

Batteries step down every six months

Battery STCs do not use deeming years. The scheme gives a factor per usable kilowatt hour, 6.8 for May to Dec 2026, falling to 5.7 on 1 January 2027, and the factor steps down every six months to the end of 2030. A 13.5 kWh battery gets 91 STCs at today's factor and 76 after the next step. The capacity above 14 kWh is tapered as well. Battery STCs has the full table to 2030.

The end of the scheme

The scheme is legislated to end with 2030. A system installed on or before 31 December 2030 gets the usual 12 months to have its certificates created, so claims for 2030 installs can still be lodged during 2031. Any extension would need a decision by parliament. Until that happens, quote and plan on the rules as they stand.