Searches for “new solar rules 1 January 2027” tend to assume a big announcement. There is not one. What happens on 1 January 2027 is a scheduled step in two existing schemes, and the interesting part is how the steps interact with a larger change that has already started, the extension of the small-scale scheme to mid-scale solar.
This page covers all three, with numbers, and answers the near-identical question “what changes on 1 January 2027 for solar and battery”. For the narrower deeming story, see the 2027 deeming period.
1. Rooftop solar: the deeming period drops a year
The Small-scale Renewable Energy Scheme deems a system’s output for a number of years and issues the STCs for them up front. The deeming period is five years for 2026 installs, four for 2027, and it keeps falling by a year each January to one year in 2030. The scheme ends on 31 December 2030. Zone ratings are 1.622, 1.536, 1.382 and 1.185 for zones 1 to 4, and the postcode decides the zone. Sydney, Brisbane, Perth, Adelaide, Canberra, the Gold Coast, Newcastle, Wollongong, Cairns and Townsville are zone 3. Melbourne, Geelong, Hobart and Launceston are zone 4. Darwin is zone 2 and Alice Springs zone 1.
STCs are kW size times zone rating times deeming years, rounded down. For a 6.6 kW system:
| Zone (example) | Rating | 2026 (5 years) | 2027 (4 years) | Difference at $38 |
|---|---|---|---|---|
| 1 (Alice Springs) | 1.622 | 53 STCs, $2,014 | 42 STCs, $1,596 | about $418 |
| 3 (Sydney, Brisbane) | 1.382 | 45 STCs, $1,710 | 36 STCs, $1,368 | about $342 |
| 4 (Melbourne) | 1.185 | 39 STCs, $1,482 | 31 STCs, $1,178 | about $304 |
The STC price has been roughly $38 to $40, with a $40 ceiling at the clearing house. The same arithmetic with the STC calculator gives your own postcode. For the schedule by year, see deeming period by year and the deeming period and zone ratings guide.
2. Batteries: the factor steps from 6.8 to 5.7
The Cheaper Home Batteries Program factor is 6.8 for May to December 2026, at the time of writing, stepping down to 5.7 on 1 January 2027 and 5.2 on 1 July 2027, and continuing down to 2030. The tiers since 1 May 2026 give 100 per cent of the factor for the first 14 kWh, 60 per cent for 14 to 28 kWh and 15 per cent for 28 to 50 kWh. Certificates round down.
| Usable kWh | STCs to 31 Dec 2026 (6.8) | STCs from 1 Jan 2027 (5.7) | Difference at $38 |
|---|---|---|---|
| 10 | 68 | 57 | $418 |
| 14 | 95 | 79 | $608 |
| 20 | 119 | 100 | $722 |
Run your size through the battery STC calculator. The short answer is in the January 2027 battery drop, and the buyer’s view is in should you buy a battery before 2027.
3. Mid-scale solar: a change that is not on 1 January
The scheme now extends to mid-scale solar. Systems above 100 kW and up to 1 MW installed from 1 October 2026 create STCs, with a fixed five-year deeming period. The Renewable Energy (Electricity) Regulations were amended in 2026, and the Clean Energy Regulator says applications open mid to late November 2026. Below 100 kW nothing changes, and above 1 MW remains LGCs. The full explanation is in our mid-scale solar STC guide.
Two points matter for 1 January. First, the mid-scale deeming period is described as fixed at five years, so unlike the small-scale table it does not step down each January. Confirm that against the CER’s guidance before you quote a 2027 job. Second, it creates a lopsided incentive: a 6.6 kW home system loses a fifth of its certificates on 1 January, while a 200 kW commercial system in zone 3 creates 200 x 1.382 x 5 = 1,382 STCs, about $52,500 at $38, on either side of the date, on that reading. See LGC vs STC and the 100 kW limit answer for the contrast.
What it does to the sales calendar
Expect a rush in November and December. Residential demand brings forward before the deeming and factor steps, then falls away in January. For installers, the practical effects are:
A bunched pipeline. Many installs land in the last weeks of December, when crews are thin and stock is tight. A job that slips over 1 January loses a year of deeming on solar, and about 16 per cent of battery certificates.
A cash-flow bulge. Certificates from December installs reach your buyer in January, just when lower factors reduce the value of new work. Plan the float with our guide on battery installer cash flow.
A quote problem. Customers who sign in November expect the 2026 discount. Say in writing that the discount depends on the installation date, and what the price becomes if the job slips.
A worked December job
An installer quotes a 6.6 kW solar system and a 10 kWh battery in Brisbane, zone 3, for installation on 17 December 2026. Solar: 45 STCs, $1,710. Battery: 68 STCs, $2,584. Total certificate value $4,294 at $38. If supply delays push both to 12 January 2027: solar 36 STCs, $1,368; battery 57 STCs, $2,166, total $3,534. The slip costs $760, which either comes off the customer’s discount or the installer’s margin. A written clause that sets who bears a delay avoids the argument.
After the step: what stays the same
Evidence, accreditation and eligibility rules do not change on 1 January. The battery needs a CEC-approved, VPP-capable battery, an accredited installer, one battery per property and the evidence rules in force since 1 March 2026. Our battery STC pillar and the STC trading guide cover the rest. The scheme-wide timeline sits at scheme changes.
What to do next
- Set a cut-off date for installs that must land before 1 January, and tell customers what it is.
- Add a delay clause to quotes so a slip is priced in advance.
- Re-run the STC value for your typical jobs at 2026 and 2027 settings.
- Plan December settlements, and check today’s rate and your buyer’s terms.
- Quote mid-scale carefully until the CER opens applications in November.