The solar rebate does not disappear in 2027. It shrinks by one year of deemed generation: systems installed in 2027 earn STCs on a 4-year deeming period instead of 5, which cuts the certificate count by one fifth. Batteries take a separate step down, from 6.8 to 5.7 STCs per kWh on 1 January 2027.
That makes 2027 a year to plan rather than panic. The reduction is mechanical and known, the scheme continues until 31 December 2030, and the market price of an STC has been capped by the $40 clearing house ceiling for years. If you know the dates and run the numbers, you can decide calmly whether December or February suits your project.
The 2027 numbers at a glance
| Item | 2026 | 2027 |
|---|---|---|
| Solar deeming period | 5 years | 4 years |
| Zone ratings | 1.622 / 1.536 / 1.382 / 1.185 | unchanged |
| Battery STC factor (per kWh usable) | 6.8 | 5.7 |
| Scheme end | 31 Dec 2030 | 31 Dec 2030 |
Zone ratings do not change. Only the year multiplier drops. The schedule continues 3 years for 2028, 2 for 2029 and 1 for 2030.
What a 2027 solar system earns
STCs = kW x zone rating x years.
- 6.6 kW in Zone 3: 6.6 x 1.382 x 4 = 36.5, so 36 STCs (45 in 2026).
- 10 kW in Zone 3: 10 x 1.382 x 4 = 55.3, so 55 STCs (69 in 2026).
- 6.6 kW in Zone 1: 6.6 x 1.622 x 4 = 42.8, so 42 STCs (53 in 2026).
At a spot price of $38, the Zone 3 6.6 kW system moves from about $1,710 to about $1,370. The difference is real, and about $340 on a system that costs several thousand dollars. It is also smaller than the price changes you see between quotes for the same system.
What a 2027 battery earns
Battery STCs equal usable kWh (within the eligible 5 to 100 kWh range, with up to 50 kWh counted) times the factor. A 13.5 kWh battery earns 13.5 x 6.8 = 91.8, so 91 STCs in 2026. From January to June 2027 it earns 13.5 x 5.7 = 76.95, so 76 STCs. At $38 that is about $3,460 versus $2,890: a drop of roughly $570 on one battery. Larger batteries lose more in absolute terms.
Read the program mechanics in our Cheaper Home Batteries installer guide and the answer on what happens on 1 January 2027. Rules on tiers changed during 2026, so use the May 2026 changes answer to confirm how your battery size is treated.
Should you wait for 2027 or install before?
Waiting for 2027 never improves the rebate. The only reasons to wait are non-rebate reasons: you need time to compare quotes, your roof needs work, or you plan to bundle a battery and want the install to be right the first time.
A simple test: take the drop in dollars (about $340 for typical solar, about $570 for a mid-sized battery) and compare it to the price difference between your best two quotes. If one installer is $1,000 cheaper and credible, the rebate shift is a footnote.
Reasons to install before 31 December:
- Your installer can commit to a firm, early-December install date.
- Your equipment is on the approved lists and in stock.
- You are ready to sign an assignment form and supply photos.
Reasons not to rush:
- The quote has gaps (no STC count, unclear battery model, no VPP capability statement).
- Your switchboard needs an upgrade nobody has scoped.
- The installer is stretched and the date keeps moving.
What changes for installers
Installers carry the cash-flow risk of a falling deeming period: a job quoted in October at 2026 values and installed in January earns fewer STCs than the quote assumed. Put the deeming year in your quote conditions, and keep your trader’s daily rate and settlement time in view when you price jobs. Our trading rates are published daily and locked on lodgement of a complete claim, which helps you protect margin on jobs already in the pipeline. See also the 2027 deeming insight and the pillar page on STC trading.
What stays the same in 2027
- The $40 clearing house ceiling and the open spot market.
- Zone ratings, product approvals and installer accreditation.
- CER audit and photo evidence rules. See how STC audits work.
- Battery eligibility conditions such as CEC-approved batteries, VPP capability and accredited installers.
A timeline you can actually use
Work backwards from 31 December. A sensible plan for a household that wants to install in 2026 looks like this:
- By early October: collect two or three quotes, each showing STC count and net price. Confirm product approvals and the installer’s accreditation number.
- By late October: sign, pay the deposit and lodge any network connection application. Distributor approvals can take several weeks, and an unapproved application is the most common cause of a missed deadline.
- By mid-November: confirm the install date in writing, and confirm stock of panels, inverter and battery.
- By early December: install, commission and take the required photos on the day.
- Before 31 December: make sure the installer has the paperwork ready to lodge, even if the claim itself goes in January.
If a step slips, decide early whether you are willing to take the 2027 numbers. Making that call on the 29th of December is how people end up with the wrong system.
Business and commercial systems
The same logic applies to small commercial systems up to 100 kW. Above 100 kW a system is outside the small-scale rules. For installs from 1 October 2026, up to 1 MW, it creates STCs with a fixed five-year deeming period (mid-scale solar STCs); above 1 MW it creates large-scale generation certificates, which have a different price and a different process. Our explanation of LGCs versus STCs sets out where the line sits.
Questions households ask about 2027
Does the zone rating change? No. Only the deeming years fall.
Will the STC price go up because there are fewer certificates? Not reliably. The $40 clearing house ceiling limits the upside, and the spot price has been roughly $38 to $40 at the time of writing.
Is it worth paying more to be installed in 2026? Only up to the size of the rebate loss for your system, about $340 for a typical solar system and about $570 for a mid-sized battery. Beyond that, you are paying for speed rather than saving money.
What to do next
- Calculate your 2026 and 2027 STCs with the tables above.
- Decide on a firm install date with a contingency buffer before 31 December.
- Collect two quotes with STC counts, and compare net price.
- If you are an installer, line up your partner onboarding before the year-end rush so your first claims are not held up.