Buying before 1 January 2027 saves roughly $400 to $700 on a typical home battery, and that is the whole prize. The federal Cheaper Home Batteries Program factor is 6.8 at the time of writing and steps down to 5.7 on 1 January 2027 and to 5.2 on 1 July 2027. If the battery suits your household anyway, a December install is a modest bonus. If it does not, the discount does not rescue the purchase.
This page is about the arithmetic and the decision, rather than the program mechanics. If you want the mechanics, the installer guide to the program covers eligibility and the 2026 changes.
The price of waiting, in dollars
The discount is the number of STCs created multiplied by what an STC sells for. The count depends on usable kWh, the three-tier structure in force since 1 May 2026 (100% on the first 14 kWh, 60% from 14 to 28, 15% from 28 to 50) and the factor. STCs have traded around $38 to $40 recently, and the clearing house ceiling is $40.
| Usable kWh | STCs at 6.8 (to 31 Dec 2026) | STCs at 5.7 (Jan to Jun 2027) | STCs at 5.2 (from 1 Jul 2027) |
|---|---|---|---|
| 10 | 68 | 57 | 52 |
| 13.5 | 91 | 76 | 70 |
| 20 | 119 | 100 | 91 |
At $38 per STC, the dollar value of each looks like this:
| Usable kWh | At 6.8 | At 5.7 | At 5.2 | Lost by waiting to January |
|---|---|---|---|---|
| 10 | $2,584 | $2,166 | $1,976 | $418 |
| 13.5 | $3,458 | $2,888 | $2,660 | $570 |
| 20 | $4,522 | $3,800 | $3,458 | $722 |
Certificates are rounded down, and the STC price moves daily, so treat these as illustrations. Run your own sizes through the battery STC calculator. The factor schedule is also in our battery STC factor answer.
Notice the second step. Waiting from January to July costs a further $228 on a 13.5 kWh battery, less than the first step. The cuts get smaller in dollar terms as the factor falls, which matters if you are tempted to wait for a better battery price.
What the hardware price has been doing
The case for waiting rests on battery prices falling by more than the rebate does. Over the past two years, installed prices per kWh have dropped as competition and volume grew, which is partly why the program’s cost ran over forecast. If the installed price of your battery fell by $700 over six months, waiting past January would be neutral. Nobody can promise that, and the market in late 2026 is less steep than 2025.
The fair reading is that the discount cut is certain and the price fall is a guess.
The cases where buying in December makes sense
- You have solar and a real evening load. A household with solar and a bill that peaks after 5 pm gets value from a battery every day.
- You already hold a quote you trust. The installer is accredited, the model is on the CEC-approved list, and the discount appears as a separate line on the quote.
- You can add a VPP or state incentive that is time-limited. See which states still have a battery rebate.
- Installer lead times are short now. Good installers fill up in the last quarter.
The cases where you should not rush
- You have no solar yet. Size and install solar first. A battery without solar charges from the grid, which weakens the case.
- The quote is vague. If you cannot see the usable kWh, the model code and the STC discount separately, fix that first.
- You use little power at night. A small household might gain more from a hot water timer or a heat pump than from storage.
- The rush forces a bad install. A battery in the wrong location or with the wrong inverter pairing costs far more than $570.
Three date traps
- Contract date is not install date. The factor on the installation date applies. Sign in November, install on 6 January, and you get 5.7.
- Slippage is common. Stock, network approval and wet weather push jobs. Ask in writing what happens to the price if the install slips past 31 December.
- Pre-existing deposits do not lock the factor. A deposit locks a price from the installer, not the certificate count.
A decision rule that fits on a card
- Would you buy this battery at the 2027 price? If yes, the December date is a bonus.
- Is the saving from beating the date more than 5% of the net price? If not, do not give up quality or time for speed.
- Has the installer committed to a date, in writing, with a stated fallback? If not, treat the deadline as a risk and not a saving.
At a net price of $9,000 for a 13.5 kWh battery, $570 is 6.3%, so the rule says the date is worth chasing only if the quote is already good. At a net price of $14,000, it is 4.1%, and the rule says do not force it.
If you are the installer
The January step lands on your margin. Any job sold at the old factor and installed after 1 January carries a loss unless the contract protects you. Write the factor on the installation date into the terms, and track every sold job against a 31 December install date from October. Cash flow matters too, because certificates for a December rush arrive in a pile at the same time. Paying attention to how long STC payment takes is worth more in December than any other month. For the program overview, see the battery STCs page.
A worked household case
Take a household with 6.6 kW of solar that shifts about 9 kWh of evening use onto a 13.5 kWh battery each day. If grid power costs 30c per kWh and exports earn 5c, each kWh stored and used later is worth about 25c. That is 9 x $0.25 = $2.25 a day, or roughly $820 a year, before VPP credits and ignoring seasonal swings.
Against that, the $570 lost by waiting from December to January equals about eight months of battery benefit. If waiting three months means three months without the benefit, you lose about $205 of savings as well. So waiting costs the household roughly $775 in total on those assumptions, which makes the case for a well-planned December install clearer. It also shows why a rushed install on a poor-fit system is the bigger loss: a battery that saves $400 a year instead of $820 takes twice as long to repay.
The sums shift with your tariff and load, so redo them with your own bill. If the household has time-of-use pricing with a large peak-to-off-peak gap, the battery is worth more. If the household has a high feed-in tariff, it is worth less. For the program background, see the federal battery rebate in 2026.
What to do next
- Get usable kWh, model code and a split discount line on every quote.
- Ask each installer for a December price and a January price.
- Run the STC count in the battery STC calculator.
- Read the rebate drop on 1 January 2027 answer for the short version.
- Installers with a December pipeline can check the daily rate on the pricing page and start trading.