Australian households and small businesses planning to install rooftop solar panels face a looming deadline, with the Clean Energy Regulator (CER) announcing a significant change to the Small-scale Technology Certificate (STC) deeming period. Effective November 1, 2026, the deeming period for new solar photovoltaic (PV) systems will be reduced from 10 years to 9 years, directly impacting the upfront financial incentive for installations.
This adjustment means that systems installed from the start of November will generate fewer STCs, leading to a reduction in the rebate amount applied to the purchase and installation cost of solar systems. For a typical 6.6 kW solar system, this change could reduce the upfront discount by approximately AUD$340 to AUD$360, while larger systems, such as 10 kW, could see a reduction of up to AUD$560, depending on the installation zone and prevailing STC market price.
Understanding the STC Deeming Period Change
The Small-scale Renewable Energy Scheme (SRES) provides financial incentives for eligible small-scale renewable energy systems through STCs. The number of STCs a system generates is calculated based on its deemed annual generation and a ‘deeming period’, which represents the expected operational life of the system for rebate purposes.
Previously, all eligible solar PV systems were assigned a 10-year deeming period. The CER’s decision to reduce this to 9 years for installations from November 1, 2026, reflects a periodic review of the scheme’s parameters, aiming to align incentives with evolving market conditions and the scheme’s legislative framework.
“The Clean Energy Regulator regularly reviews the parameters of the Small-scale Renewable Energy Scheme to ensure its ongoing effectiveness and alignment with government policy. The adjustment to the STC deeming period for solar PV systems, effective 1 November 2026, is a result of this review and will impact the number of certificates generated by new installations.”
Financial Impact on Your Solar Installation
The value of an STC fluctuates based on market demand and supply, typically trading between AUD$38 and AUD$40. To illustrate the impact, consider a common 6.6 kW solar system installed in Zone 3 (e.g., Sydney, NSW), which has a deemed annual generation factor of 1.382 MWh per kW:
| System Size | Deeming Period | Annual Generation Factor | Total STCs (Rounded) | STC Value (at AUD$38) | STC Value (at AUD$40) |
|---|---|---|---|---|---|
| 6.6 kW | 10 Years | 1.382 MWh/kW | 91 | AUD$3,458 | AUD$3,640 |
| 6.6 kW | 9 Years | 1.382 MWh/kW | 82 | AUD$3,116 | AUD$3,280 |
| Difference | 9 STCs | AUD$342 | AUD$360 |
For a larger 10 kW system in the same zone:
| System Size | Deeming Period | Annual Generation Factor | Total STCs (Rounded) | STC Value (at AUD$38) | STC Value (at AUD$40) |
|---|---|---|---|---|---|
| 10 kW | 10 Years | 1.382 MWh/kW | 138 | AUD$5,244 | AUD$5,520 |
| 10 kW | 9 Years | 1.382 MWh/kW | 124 | AUD$4,712 | AUD$4,960 |
| Difference | 14 STCs | AUD$532 | AUD$560 |
This reduction in STC generation directly translates to a smaller upfront discount on your solar system. Installers typically claim the STCs on behalf of the customer and apply the value as a discount on the invoice.
Who is Affected and What to Do
This change will affect any new solar PV system installed and registered with the CER from November 1, 2026, onwards. Systems installed and registered before this date will still qualify for the 10-year deeming period.
For homeowners and businesses who have been considering solar, this announcement creates a clear incentive to accelerate their plans. Securing a quote and completing installation before the end of October 2026 will ensure eligibility for the higher STC rebate value.
Beyond the federal STC scheme, various state-level rebates and incentives may also be available, which can further reduce the cost of solar and battery installations. For a comprehensive overview of available support, consult Your 2026 Guide: Claim Up To $15,000 in Energy Rebates Across Australia.
Choosing the right solar panels can also significantly impact long-term savings, with technologies like N-Type panels offering higher efficiency and better performance over time. Learn more at N-Type vs. P-Type Solar Panels in Australia 2026: Unlock $1,000+ Extra Savings Annually.
This change underscores the dynamic nature of government incentives for renewable energy. Acting promptly can help maximise your savings and accelerate your transition to cleaner, more affordable energy. For those looking to electrify their entire home, understanding all available incentives is key to significant savings, as detailed in Electrify Your Home in 2026: Real Costs, Rebates & Savings Up to $15,000+.