The question sounds like a gamble on the market. It is closer to arithmetic with three moving parts: the discount, which steps down on a published calendar; the hardware price, which tends to drift down; and the electricity savings you give up for every month you wait. The first is known, the second is uncertain, and the third is the one people forget.
Here is a worked comparison with stated assumptions, so you can swap in your own. For the schedule itself, see the factor schedule to 2030.
The discount is on a timetable
Under the Cheaper Home Batteries Program, STCs for a battery depend on usable kWh, a size-tier structure, and a factor. At the time of writing the factor is 6.8 until 31 December 2026, stepping down to 5.7 on 1 January 2027 and 5.2 on 1 July 2027, and continuing down to 2030. The first 14 kWh earn 100 per cent of the factor, 14 to 28 kWh earn 60 per cent and 28 to 50 kWh earn 15 per cent.
For a 10 kWh battery at $38 per STC (the market has been roughly $38 to $40):
- At 6.8: 68 STCs, $2,584
- At 5.7: 57 STCs, $2,166
- At 5.2: 52 STCs, $1,976
The CER sets the factor with falling battery costs in mind, with the intention of keeping the discount at roughly a constant share of price. That is the key to the wait-or-buy question: if hardware prices fall, the rebate falls with them, so a lower sticker price does not mean a lower net price by the same amount.
The comparison
Assumptions, all illustrative: a 10 kWh usable battery installed for $10,000 before the STC discount today; a hardware and installation price decline of about 5 per cent over six months and 10 per cent over twelve; and electricity savings of about $775 a year, or about $65 a month, from shifting solar into the evening. (We derive that figure on our payback page.)
| Install date | Price before STCs | STC discount | Net price | Savings forgone by waiting | Net position vs buying now |
|---|---|---|---|---|---|
| December 2026 | $10,000 | $2,584 | $7,416 | $0 | baseline |
| June 2027 | $9,500 | $2,166 | $7,334 | about $390 | about $308 worse |
| December 2027 | $9,000 | $1,976 | $7,024 | about $775 | about $383 worse |
On these assumptions the cheaper net price from waiting is more than eaten by the savings you give up. The six-month wait saves $82 on the net price and costs $390 in forgone savings. The twelve-month wait saves $392 and costs $775.
What would make waiting win
Flip the question: how far would the price have to fall to justify waiting? For a twelve-month wait, you need the net price to fall by at least the $775 of lost savings, so to $6,641 or below. With a $1,976 discount, that means a pre-STC price of about $8,617, a fall of roughly 14 per cent. For a six-month wait, the price needs to fall about 8 per cent, to about $9,192.
Prices have been falling, but whether they fall faster than those thresholds is unknowable from here. If you believe they will, wait. If you are not sure, the arithmetic leans towards buying a battery you need.
When the sums do not apply
The model assumes you will use the battery well from day one. Cases where waiting is rational:
You do not have solar. A battery without solar mostly charges from the grid, which only works on certain tariffs. Size solar first, then the battery.
Your usage is low. If your evening load is 3 kWh, a 10 kWh battery sits half empty. The savings figure falls and the payback stretches.
You have not compared quotes. Quotes for the same battery can differ by thousands of dollars. Getting three quotes can be worth more than any rebate step.
A better incentive is coming. State schemes and retailer offers change. At the time of writing, several state battery schemes have closed (Queensland Battery Booster, the Victorian solar battery loan, the Tasmanian Energy Saver Loan and the NT scheme), while WA’s remains active with VPP required. Check what exists in your state before assuming it will return.
The year-end rush problem
Waiting is not the only way to lose. Rushing is the other. A job squeezed in before 31 December can mean a poorly planned installation, a battery that was not the best fit, or a missed step in the paperwork that leaves the STC claim exposed. Installation evidence rules tightened from 1 March 2026, and a claim with weak photos can be delayed or rejected. The discount you chase is only worth having if the claim clears. Our battery STC submission checklist shows what a clean job looks like.
If your install risks sliding past the date, check what the contract says. The factor that applies is the one in force on the installation date, so a delay of a week can cost you the full step. Ask in advance who bears that cost.
How the VPP changes the picture
The program requires a VPP-capable battery, though not that you join a VPP. If you do join one, the incentives can add to the first-year return and can shorten the payback, but the terms vary and some tie you in. Our pieces on whether joining a VPP is worth it and VPP providers in 2026 work through those choices.
Sensitivity: change one assumption at a time
The result above rests on three guesses. Here is what happens if each one moves, holding the others fixed, for a twelve-month wait.
If savings are $500 a year rather than $775, the forgone amount is $500. Waiting then costs about $108 net, so it is nearly neutral. A household with a modest evening load, or a cheap flat-rate tariff, is closer to the “wait” side. If savings are $1,000, because you pay a high peak rate and export at a very low feed-in tariff, waiting costs about $608 net, so buying sooner is clearer.
If hardware prices fall 20 per cent instead of 10, the pre-STC price is $8,000, the net price is $6,024 and the saving is $1,392 against $775 forgone, so waiting wins by about $617. That is the case people have in mind when they say “wait”. It requires a faster fall than recent trends suggest, and a price drop on that scale would also be a signal that the factor may step down faster still.
If the STC price falls from $38 to $32, every discount shrinks by about 16 per cent, which makes the current factor worth less to you but does not change the basic shape. Treat STC price as a risk on both sides of the comparison. The market has traded at about $38 to $40 against a $40 ceiling, so the upside is capped and the downside is not.
The lesson from the sensitivity is that your own tariff and usage matter more than the macro question. A household that saves $1,000 a year should buy when ready. A household that saves $400 a year has a harder case for a battery at all, regardless of timing.
Short answers on this topic: battery stc factor 5 7.
What to do next
- Run your own numbers in the battery STC calculator for 2026 and 2027.
- Get three like-for-like quotes and ask for the December and January versions.
- Work out your own savings before you start: evening usage, tariff and feed-in rate.
- Read the battery STC pillar and the battery rebate answer on timing.
- Installers: see how battery STC trading works and check today’s rate.