Most of what will change for solar in 2027 is already written into legislation, which makes it one of the few policy years you can plan for. The numbers below are scheduled rule changes, not predictions. The unknowns sit further out, and we mark them clearly.
1 January 2027: deeming drops to four years
The small-scale solar deeming period is the number of years of expected generation a system claims up front as STCs. It is 5 years for 2026 installs and 4 for 2027, falling by one year each year to 1 in 2030, when the scheme ends on 31 December. The zone ratings do not change: 1.622, 1.536, 1.382 and 1.185 for zones 1 to 4.
A standard 6.6 kW system in a zone 3 postcode (Sydney, Brisbane, Perth, Adelaide, Canberra):
| Install year | Calculation | STCs | At roughly $38.50 |
|---|---|---|---|
| 2026 | 6.6 x 1.382 x 5 | 45 | about $1,730 |
| 2027 | 6.6 x 1.382 x 4 | 36 | about $1,390 |
That is a 9-certificate drop, about $345 on a standard system. In zone 4 (Melbourne, Geelong, Hobart, Launceston), 6.6 x 1.185 x 5 = 39 becomes 6.6 x 1.185 x 4 = 31. Our full walkthrough is what changes in January, and you can run any postcode in the STC calculator.
1 January 2027: the battery factor steps down
For the Cheaper Home Batteries Program the factor is 6.8 for installs from May to December 2026. It steps to 5.7 on 1 January 2027, then to 5.2 on 1 July 2027, and keeps stepping to 2030. On a 14 kWh battery:
| Period | Factor | STCs | At roughly $38.50 |
|---|---|---|---|
| May to Dec 2026 | 6.8 | 95 | about $3,660 |
| Jan to Jun 2027 | 5.7 | 79 | about $3,040 |
| Jul to Dec 2027 | 5.2 | 72 | about $2,770 |
The tiers still apply: first 14 kWh at 100%, 14 to 28 kWh at 60%, 28 to 50 kWh at 15%. See the battery factor for 2027 for the full picture.
Mid-scale solar beds in
From 1 October 2026, systems above 100 kW and up to 1 MW create STCs with a fixed five-year deeming period, per the amended Renewable Energy (Electricity) Regulations. The CER says applications open mid to late November 2026, so 2027 is the first full year of this running at volume. A fixed five-year period means mid-scale systems do not suffer the same step-down as small systems in January. A 200 kW zone 3 system creates 200 x 1.382 x 5 = 1,382 STCs whether it is installed in 2026 or 2027, because the five-year period is fixed. That changes the commercial quoting calculation, so read mid-scale solar and STCs before pricing next year’s commercial jobs.
The Small-scale Technology Percentage for 2027
Each year the CER publishes the percentage for the coming year, and it is the demand side of the certificate market. The 2026 figure is 11.67%, built on high-scenario projections that allow for battery volume. The 2027 percentage should be published on the CER’s small-scale technology percentage page, and you should read it there rather than rely on a forecast. The direction of travel is clear enough: deeming falls, so each rooftop system creates fewer certificates, while batteries and now mid-scale solar add volume. The balance between those forces is what the percentage tries to match. A well-matched percentage keeps the price near the $40 ceiling, and a mismatch is what moves it.
What 2027 does not change
- The $40 clearing house price. It is a scheme feature and it is not scheduled to change
- The zone ratings
- The accreditation and evidence expectations from 2026, including the battery photo rules from 1 March 2026
- The 2030 end date for small-scale solar certificates
Anything that sounds like a 2027 announcement on top of this, for example a new state incentive or a change to the household income cap, should be checked against the scheme’s own page.
Quoting in 2027: the practical consequences
Customers will compare 2027 quotes with 2026 ones. The honest answer is that the discount is smaller because the rules say so, not because the installer is padding. The best defence is a quote that shows the certificate count on its face. Another point: for jobs signed in late 2026 and installed in 2027, the install date controls the entitlement. That needs to be in your contract.
From the desk: Treat the January step as a pricing date, not a marketing event. List the 2026 and 2027 discount side by side on the quote and tell the customer which one applies if the install slips. We see arguments in February from installers who promised a 2026 discount on a 2027 install and have no way of recovering the difference.
State programs to check
State incentives are the least certain part of 2027. Victoria’s Solar Victoria household income cap fell to $150,000 on 1 July 2026, and Victorian Energy Upgrades targets run through 2027. NSW’s Energy Savings Scheme and Peak Demand Reduction Scheme continue, with the NSW battery incentive having moved into the federal program in 2025 and a PDRS incentive for VPP connection. Always check the scheme’s own page before quoting a state-based number.
A sample 2027 quote for a combined job
Take a Sydney customer who wants 6.6 kW of solar and a 14 kWh battery installed in February 2027. Solar creates 6.6 x 1.382 x 4 = 36 STCs. The battery at the 5.7 factor creates 79. That is 115 certificates, about $4,430 at $38.50. The same job in December 2026 creates 45 plus 95, which is 140 certificates, about $5,390. The difference of 25 certificates is roughly $960. It is a real number, but it is not a reason to install a system the household is not ready for, and it is not a reason to rush a roof inspection or a switchboard upgrade.
Should customers rush?
Sometimes. If your customer is going to install anyway, a December install beats a January one by a few hundred dollars. If they are not ready, buying early to save $345 is a bad trade. See should you buy solar before 2027 for the honest framing, and our article on pull-forward demand in December for what it does to your schedule.
Related answers
If a customer asks what the January change means for them, two short answers help: how the solar rebate drops on 1 January and the STC calculator for 2027. Both use the same schedule as this article.
What to do next
- Put 1 January and 1 July 2027 in your crew calendar as pricing dates
- Re-quote any signed-but-uninstalled jobs with install date clauses
- Check today’s published rate on pricing and read about STC trading
- Keep the scheme changes hub as your single reference