Cheaper Home Batteries: What the Discount Takes Off, and the Size That Pays Back

Two numbers decide what the Cheaper Home Batteries Program takes off the price of a solar battery, and neither of them is the price. The first is the battery’s usable capacity in kilowatt hours. The second is the date it is installed, because the discount is set by a factor that the Department of Climate Change, Energy, the Environment and Water (DCCEEW) has scheduled to fall every six months, and the next step, from 6.8 to 5.7, arrives on 1 January 2027. A household pricing a battery in the last months of 2026 is therefore pricing against a figure that is about to move. The calculator below applies the published factors to a size and an install date; the sections after it explain each input and what the result leaves out.

How the discount is calculated

The program does not pay a rebate in the usual sense. DCCEEW describes it as a discount of around 30 per cent on the cost of an eligible small-scale battery, delivered through small-scale technology certificates (STCs) under the Small-scale Renewable Energy Scheme (SRES). A battery of between 5 kWh and 100 kWh creates certificates when it is installed, and the number it creates depends on its usable capacity multiplied by the STC Factor that applies on the install date.

The certificates carry a value because they can be sold. DCCEEW explains that the government buys the equivalent STCs through the Clearing House, and installers pass the value on to the household as an upfront reduction on the quote. A household can instead create and claim the certificates itself through the REC Registry. In either case there is nothing to apply for: the installer applies the discount, or the owner makes the claim.

Written as arithmetic, the mechanism is short:

discount = usable kWh (after the taper) x STC Factor on the install date x price per STC

Each term in that line carries a condition, and the conditions are where most of the confusion about the program sits. Short videos on the subject describe the discount as “around 25 to 30 per cent” in one place and “up to 30 per cent” in another, and both can be accurate for different batteries on different dates, because the percentage is an output of the formula rather than a fixed rate. The three terms are taken in turn below.

The taper, worked through

From 1 May 2026 the factor no longer applies evenly to every kWh. DCCEEW sets out a taper by capacity:

• the first 14 kWh earn certificates at 100 per cent of the factor
• each kWh above 14, up to 28 kWh, earns at 60 per cent
• each kWh above 28, up to 50 kWh, earns at 15 per cent
• capacity above 50 kWh earns no certificates

Applied to three battery sizes at the 2026 factor of 6.8 and the Clearing House price of $40 per STC, the taper produces the figures below. Certificate counts are rounded down to whole certificates, and every figure is an estimate; the REC Registry calculator gives the exact count for a specific system.

The 20 kWh row shows the first effect of the taper. Its second 10 kWh adds about $2,040, against $2,720 for the first 10. The 40 kWh row shows the larger one: doubling capacity again, from 20 to 40 kWh, adds about $1,800, because twelve of the additional kWh sit in the band that earns at 15 per cent. Across the table the discount per kWh falls from $272 to $164, a reduction of about 40 per cent for a battery four times the size.

DCCEEW makes the same point in its own terms, advising that a bigger battery is not necessarily a better one and that a battery sized beyond a household’s needs can limit the benefits. In effect, the taper builds that advice into the discount.

It is also the reason the change drew attention among battery owners. One widely read thread on a frugal living forum asked whether the rebate was “still worth it and what’s the right size?”, and a commenter who had bought a large battery described their discount falling sharply under the new rules. That account is one person’s experience and is not used as data here, but its direction matches the table: the larger the battery, the more of it sits in the lower bands.

The date that changes it

The second input is the install date. The STC Factor is set by the date the battery is installed, not the date it is ordered or quoted, and DCCEEW publishes the schedule:

After 2027 the factor continues to step down every six months until it reaches 2.1 in late 2030. DCCEEW also states that the program is reviewed at least annually, so the schedule is the published path rather than a guarantee that every later step will apply as written.

The effect of the January step on the same three batteries, with the same taper and the same $40 price, is as follows.

A 10 kWh battery installed in January 2027 earns about 57 certificates, worth about $2,280, against about $2,720 for the same battery installed in December 2026. In proportion the reduction is the same at every size, about 16 per cent, because the factor multiplies every effective kWh equally. In dollars it grows with the battery.

Two cautions belong beside this table. First, the relevant date is installation, so a quote signed in November for a battery installed in January falls under the 2027 factor, and a household relying on the 2026 figure should have the install date confirmed in writing. Second, the comparison isolates the factor and holds everything else still. A price quoted in January need not match one quoted in December, and the installer’s valuation of each certificate can move as well.

The $40 is a ceiling, not a promise

The third term, the price per STC, is the one most often treated as fixed when it is not. DCCEEW states that the Clearing House price is $40 per STC, excluding GST. That price is set. The open market for certificates, however, varies, and an installer that sells certificates on the open market, or values them conservatively when building a quote, may credit less than $40 for each one. Retailers may also include administration fees.

DCCEEW requires retailers to show the discount clearly against the system price, which gives a household something to check. The more useful request is narrower: the number of certificates the battery will create, and the price per certificate the installer has applied. With those two figures in writing, the discount can be reproduced on a phone calculator and two quotes can be compared on the same basis. Without them, a quoted discount is a single number whose parts cannot be checked against each other.

The calculator above prefills $40 for this reason, and the field can be changed. A quote that credits $36 per certificate on a 13.5 kWh battery, for instance, moves the discount on about 91 certificates from about $3,640 to about $3,276. The difference is better known before signing than after.

What the discount does not cover

The formula applies to a defined object, and several things sit outside it. According to DCCEEW:

1. Batteries under 5 kWh are not eligible, and neither are systems over 100 kWh.
2. Only the first 50 kWh of usable capacity creates certificates, so capacity above that figure carries its full cost.
3. The battery must be installed by an installer accredited by Solar Accreditation Australia, and the battery and inverter must be on the Clean Energy Council’s approved product list.

A fourth limit is practical rather than regulatory. The certificates attach to the battery’s eligible capacity. Installation extras that are often bundled into a quote, such as switchboard work, are not discounted unless the quote says so, and a household comparing two quotes should check where the discount has been applied as well as how large it is.

State and territory schemes may also be available in some places. DCCEEW notes that they may stack with the federal discount, and their conditions belong to each state or territory, so they need to be checked locally rather than assumed.

Payback, honestly

Payback is the figure most quotes present and the one that depends most on assumptions the quote does not show. The arithmetic is simple:

simple payback (years) = net cost after discount / expected yearly bill saving

The calculator’s check values illustrate it. A 13.5 kWh battery quoted at $12,000 before the discount earns about 91 certificates at $40, a discount of about $3,640, which leaves a net cost of $8,360, or about 30 per cent off the quote. If the household’s bills fall by $1,000 a year, the simple payback is about 8.4 years. If they fall by $700, it is about 11.9 years.

The denominator is the uncertain term, and this article gives no figure for it, because the saving depends on things that differ from one household to the next: how much electricity is used in the evening, how much solar would otherwise be exported, and the tariff the household pays. A household that runs most of its load in daylight, while the panels are producing, has less for a battery to shift. One with heavy evening use has more. Appliances that run at night are the obvious place to start, and the thinker breakdown of what an electric blanket costs to run is a useful model for estimating one load at a time. An electric vehicle charged overnight is a much larger evening load. A household weighing one alongside a battery may want the tax side as well, set out in the piece on the EV fringe benefits tax break on a novated lease, since the car and the battery are likely to be sized against the same bills.

DCCEEW’s sizing advice points the same way. It recommends discussing daily energy use, solar output and inverter capacity with the installer, and warns that a battery that is too large can limit benefits. Read against the taper, the advice has a second edge: the kWh a household is least likely to use are also the ones that earn the smallest discount.

Simple payback also leaves things out. It takes no account of battery degradation, future tariff changes, or the cost of money tied up in the purchase. It is a comparison figure, useful for ranking two quotes against the same bills, and much weaker as a forecast.

Getting quotes

DCCEEW sets out steps for households looking at a battery, and they reduce to a short sequence:

1. Obtain more than one quote.
2. Confirm that the battery is on the Clean Energy Council’s approved list and that a Solar Accreditation Australia accredited installer will be on site.
3. Ask for the value of the discount, the number of certificates, the price per certificate and the expected install date.
4. Ask for the warranty terms and the installer’s estimate of payback, with the yearly saving it assumes.

Item 3 does most of the work. The certificate count fixes the taper and the factor, the price per certificate fixes the third term, and the install date confirms which factor applies. Item 4 turns the installer’s payback figure into something that can be tested against the household’s own bills.

Size it to your evenings

The discount rewards a battery sized to what a household uses after the sun goes down. The first 14 kWh earn the full factor, every kWh beyond them earns less, and from 1 January 2027 every kWh earns less again. A household that knows its evening use from its own bills can size the battery to that figure, ask the installer for the certificate count and the price per certificate, and check whether installation can be completed before the factor changes. A household that does not yet know its evening use has a more useful first task than collecting quotes.

This article is general information based on DCCEEW’s published factors and is not financial advice. The REC Registry calculator and the installer’s written quote are the sources for any individual system.

Sources: Cheaper Home Batteries Program, Department of Climate Change, Energy, the Environment and Water (https://www.dcceew.gov.au/energy/programs/cheaper-home-batteries); Eligibility information for the Cheaper Home Batteries Program, DCCEEW (https://www.dcceew.gov.au/energy/programs/cheaper-home-batteries/eligibility-information); Small-scale technology certificates (STCs) for batteries, DCCEEW (https://www.dcceew.gov.au/energy/programs/cheaper-home-batteries/small-scale-technology-certificates)