If you are thinking about solar, the clock is real but it is not frantic. On 1 January 2027 the federal solar discount shrinks by about a fifth, and a typical 6.6 kW system loses about $350 of STC value. That is a good reason to get moving. It is not a good reason to sign the first quote you are offered.
This guide gives you the numbers, shows how the lost discount compares with the other things that decide whether solar is worth it, and lays out a sensible timeline if you do want to install before the end of the year. It is written for homeowners. If you are an installer looking at the same change, see deeming period 2027.
What actually changes on 1 January 2027
The solar rebate is a number of STCs created when your system is installed, and each STC is worth roughly $38 to $40 at the time of writing. The number is your system size in kW, multiplied by a zone rating for your postcode, multiplied by the deeming period in years. In 2026 the deeming period is five years. In 2027 it is four. Nothing else in the formula changes. Your installer usually takes the STCs and gives you the value as a discount on the quote, as explained in how the solar rebate works.
What waiting costs
For a 6.6 kW system, the loss by zone is:
| Zone | 2026 STCs | 2027 STCs | Lost value at $39 |
|---|---|---|---|
| 1 (1.622) | 53 | 42 | about $429 |
| 2 (1.536) | 50 | 40 | about $390 |
| 3 (1.382) | 45 | 36 | about $351 |
| 4 (1.185) | 39 | 31 | about $312 |
Sunnier zones are worth more because the zone rating is higher. A 10 kW system in zone 3 loses 14 STCs, about $546. The number is real, but compare it with the rest of the decision.
Weighing it against the other numbers
The discount is a one-off. The things below keep paying or costing you for 20 years.
- System price. A system installed for $6,500 after a $1,755 discount costs you $4,745 net. After a $1,404 discount in 2027 the same system, at the same gross price, costs $5,096. The gap is about 7 percent of the net cost.
- Payback. If the system saves $1,100 a year on bills and export, a $351 extra upfront cost lengthens payback by roughly four months. That is a real cost, but small beside the 20-plus years of savings.
- Quality of installer and equipment. A cheap quote from an installer who disappears is more expensive than $351. Check accreditation and warranties.
- Your own usage. A house that is empty all day may gain more from a smaller system, or a battery, than a rushed large one.
- Equipment prices. Panel and inverter prices have tended to fall over time, which can offset part of the shrinking discount. That is not guaranteed.
Use those figures as illustrations only. Your quote will differ.
The sensible timeline
If you want the 2026 deeming period, the job has to be installed and commissioned by 31 December. The date that counts is the installation date, not the date you sign. Work backwards:
- Now to early October. Get two or three quotes and compare them like for like. Our STC solar quote guide explains how the discount appears.
- October. Choose an installer and confirm in writing the install date, the STC count and the system details.
- October to November. Any network approval or switchboard work happens here. Lead times from the network can be several weeks.
- November to early December. Install and commission. Leave buffer for weather and supply delays.
- Late December. Installers get busy and crews book out. A date at the edge of the deadline is a risk.
If your date is not firm by the start of November, you are probably in the 2027 deeming period, and that is not a disaster.
From the desk: be wary of an installer who offers to “lock in the 2026 rebate” for a job that will clearly be installed in 2027. The deeming period is set by the installation date. No contract can change that, and a backdated install date is a compliance breach. If a salesperson tells you otherwise, walk away.
Red flags created by deadline pressure
Deadlines produce pushy sales. Watch for:
- “The rebate ends this month.” It does not end. It steps down.
- A quote with no STC count shown. You should see how many STCs and what dollar value is applied.
- A huge STC discount. At roughly $38 to $40 an STC, 45 certificates is about $1,750. A claimed discount well above that for a standard system needs explaining. See is the STC rebate a scam.
- Pressure to sign today. Genuine installers will hold a quote for a reasonable period.
- An installer you cannot verify. Ask for the Solar Accreditation Australia number and check it. The check installer accreditation answer shows how.
Should you also think about a battery
If you want a battery, that has its own date. The Cheaper Home Batteries Program STC factor is 6.8 per kWh for 2026 installs, stepping down to 5.7 on 1 January 2027 and 5.2 on 1 July 2027 (the factor now steps every six months to 2030), and it keeps stepping down every six months. If you are considering solar and a battery together, the time pressure applies to both. The battery rebate answer explains the change, and our should I buy a battery before 2027 guide covers the battery decision on its own.
When waiting is the right call
Sometimes it is. If your roof needs repairs, your electricity use is about to change, you are not sure of your plans for the property or you are not comfortable with the quotes you have, waiting costs you about $350 and may save you much more. The discount is one input to a decision about a system you will live with for two decades.
A simple way to decide
Write down three numbers: the extra cost of waiting, about $350 for a typical system, the price difference between your best two quotes and the number of years you plan to stay in the home. If the quote difference is larger than the STC loss, choose on installer quality and price rather than the calendar. If you will stay for ten years or more, the $350 is a small share of what the system saves you. If you may sell within a few years, a smaller system, or waiting until you are sure, can make more sense than rushing for a discount that is a fraction of the total outlay.
What to do next
- Get two or three written quotes showing system size, STC count and the dollar value applied.
- Ask each installer for their accreditation number and check it.
- Decide by early November if you want a 2026 install, and confirm the install date in writing.
- Read how the solar rebate works for the full mechanism and who gets the STCs so you know what you are signing.
- Use the resources hub if you want the deeper detail on forms and paperwork.