What changes on 1 January 2027
The federal solar discount is paid in small-scale technology certificates, and the number a system earns is its size times a zone rating times a deeming period. The Clean Energy Regulator reduces the deeming period by one year each year until the scheme ends in 2030: 5 years for a system installed in 2026, 4 years in 2027, then 3, 2 and 1. A 6.6 kW system in Zone 3 (Sydney, Brisbane, Perth, Adelaide, Canberra) earns 45 certificates worth $1,755 this year and 36 worth $1,404 next year, so the quote rises by $351 unless the installer absorbs it. The table gives every zone for 6.6 kW and the 10 kW step.
| Zone | Installed in 2026 | Installed in 2027 | Rise on 6.6 kW | Rise on 10 kW |
|---|---|---|---|---|
| Zone 1 (rating 1.622) | 53 certificates, $2,067 | 42 certificates, $1,638 | $429 | $663 |
| Zone 2 (rating 1.536) | 50 certificates, $1,950 | 40 certificates, $1,560 | $390 | $585 |
| Zone 3 (rating 1.382) | 45 certificates, $1,755 | 36 certificates, $1,404 | $351 | $546 |
| Zone 4 (rating 1.185) | 39 certificates, $1,521 | 31 certificates, $1,209 | $312 | $468 |
The battery program steps down on the same day: 6.8 certificates per usable kWh becomes 5.7, so the discount on a 10 kWh battery falls from $2,652 to $2,223 and on 14 kWh from $3,705 to $3,081.
What it means for each capital
The index reading for October 2026 is the standard 6.6 kW installer offer after this year's discount. The last column adds the January step to it, which is the price if installers' own charges do not move; whether they do is what the January index reading will show, since hardware prices have fallen most years and may offset part of the step.
| Capital | STC zone | October 2026 offer | January step | Offer if prices hold |
|---|---|---|---|---|
| Sydney | Zone 3 | $6,170 | $351 | $6,521 |
| Melbourne | Zone 4 | $6,218 | $312 | $6,530 |
| Brisbane | Zone 3 | $6,756 | $351 | $7,107 |
| Adelaide | Zone 3 | $5,812 | $351 | $6,163 |
| Perth | Zone 3 | $5,294 | $351 | $5,645 |
| Hobart | Zone 4 | $7,544 | $312 | $7,856 |
| Canberra | Zone 3 | $6,144 | $351 | $6,495 |
| Darwin | Zone 2 | $10,250 | $390 | $10,640 |
The install-date rule: installed, not signed
The deeming period is set by the date the system is installed and commissioned, not the date the contract is signed or the deposit paid. A system quoted in November 2026 at this year's discount and installed on 5 January 2027 earns the 2027 certificates, and a quote that promises otherwise is carrying the difference itself or will revise the price. For an installation to count in 2026 it has to be complete, with the compliance paperwork and the certificate assignment form dated on or before 31 December 2026; installers book out in December every year for this reason, and the same rule applies to the battery factor.
Two things the step does not change: the certificate price itself (the site assumes $39, with the market near the $40 clearing-house cap), and the zone ratings, which stay at 1.622, 1.536, 1.382 and 1.185. It also does not make December the right time to buy a system that is not otherwise worth it: $351 on a $6,170 Sydney system is a 6 per cent rise, less than the gap between a standard and a premium quote.
What to do with a quote in hand
Check which year's certificates the quote assumes: the STC line should show the certificate count, and 45 on 6.6 kW in Zone 3 means 2026, 36 means 2027. Ask for the installation date in writing. If the installer cannot commit to a 2026 date, ask whether the quoted price holds at the 2027 certificate count. The quote check reads the STC line from a photo of the quote and reports the year it matches; the STC calculator gives the certificate count for any size, postcode and install year.
January 2027 questions
Will solar prices go up in 2027?
$312 to $429 is the rise on a 6.6 kW system from 1 January 2027 if installer prices hold, from the STC deeming period falling from 5 to 4 years; $546 on 10 kW in Zone 3. Hardware price falls may offset part of it.
How much is the STC rebate dropping in 2027?
$312 (Zone 4, Melbourne and Hobart) to $429 (Zone 1) on a 6.6 kW system, and $546 on 10 kW in Zone 3, at $39 per certificate. The certificate count on 6.6 kW in Zone 3 falls from 45 to 36.
Does the solar rebate end in 2027?
4 years is the 2027 deeming period, so no: the scheme runs to 2030 with the period falling by one year each year (3 years in 2028, 2 in 2029, 1 in 2030), and the discount shrinks each January.
What is the battery rebate from January 2027?
$2,223 on a 10 kWh battery, down from $2,652, as the factor falls from 6.8 to 5.7 certificates per usable kWh; $3,081 on 14 kWh, down from $3,705.
Do I need my solar installed by 31 December 2026 to get the 2026 rebate?
45 certificates on 6.6 kW in Zone 3 apply only to a system installed and commissioned on or before 31 December 2026; one installed in January 2027 earns 36. The contract date does not matter.
Is it worth rushing to buy solar before 2027?
$351 is the Zone 3 step on 6.6 kW, 6 per cent of a $6,170 Sydney system, so the rush is worth a few hundred dollars and not a rushed installer choice. A system worth buying in December is worth buying in February at the smaller discount.