On 1 May 2026 the Cheaper Home Batteries Program changed shape. The discount now tapers with size: the full certificate rate applies up to 14 kWh, every kWh from 14 to 28 earns 60 per cent of it, and every kWh from 28 to 50 earns 15 per cent, on the energy department's program page. The rate per kWh also began stepping down every six months (the full schedule to 2030 is here). Five months on, the regulator's September-quarter data workbook lets us see what people actually bought on either side of that date. It is the data that will go into the full Quarterly Carbon Market Report, which the CER expects by mid-December.
1. The middle size band now takes most installs
The CER splits approved batteries into the same bands the taper uses, before and after 1 May. The 14 to 28 kWh band went from a little over a third of installs to well over half. The 28 to 50 kWh band, which was the most common size before the change, fell to just over a quarter. Batteries over 50 kWh, beyond the last tier in the department's taper table (the program still covers batteries up to 100 kWh), almost disappeared, from 3.5 per cent to 0.6. The smallest band, up to 14 kWh and paid at the full rate, barely moved.
Bands in kWh of usable capacity. "Before" is installations from 1 July 2025 to 30 April 2026; "after" is 1 May to 30 September 2026. The CER puts a battery on a band boundary in the lower band, so a 14 kWh battery counts as "up to 14". Source: CER, QCMR Q3 2026 data workbook, Figure 3.2.
This matches what our own sums of the CER's postcode data showed from the other direction: the average battery peaked at about 37 kWh in April and has sat in the low to mid-20s since (those figures are here). The size bands say where the average went. The shift was out of the 28 to 50 kWh band and into the 14 to 28 band, not down to the smallest batteries paid at the full rate, which fits the taper: it moved to sizes where every kWh still earns full or 60 per cent support and none falls into the 15 per cent band.
2. A smaller share of batteries are going on existing solar
The CER also sorts each battery by how it relates to the solar system it is connected to, which it must be for the discount. A retrofit is a battery installed more than 90 days after the solar. The other two types are installed within 90 days of a solar job: with brand-new solar at that address, or with a replacement, extension or addition to an existing system.
From July 2025 to April 2026, retrofits were between 50.3 and 54.8 per cent of installs every month. From May to September 2026 they were between 38.8 and 43.7 per cent. Batteries installed with brand-new solar went the other way, from 23.5 to 29.8 per cent a month before May to between 31.3 and 37.2 per cent since. Batteries with upgraded solar held at about a fifth to a quarter throughout, apart from a dip to 15.4 per cent in April.
| Month installed | Retrofit to existing solar | With new solar | With upgraded solar |
|---|---|---|---|
| Jul 2025 | 52.6% | 26.2% | 21.2% |
| Aug 2025 | 54.5% | 23.6% | 21.9% |
| Sep 2025 | 52.1% | 24.6% | 23.3% |
| Oct 2025 | 53.9% | 23.5% | 22.6% |
| Nov 2025 | 51.6% | 25.8% | 22.6% |
| Dec 2025 | 50.3% | 28.1% | 21.6% |
| Jan 2026 | 53.2% | 25.8% | 21.0% |
| Feb 2026 | 51.7% | 26.8% | 21.5% |
| Mar 2026 | 52.0% | 27.3% | 20.7% |
| Apr 2026 | 54.8% | 29.8% | 15.4% |
| May 2026 | 43.2% | 34.4% | 22.4% |
| Jun 2026 | 38.8% | 37.2% | 24.0% |
| Jul 2026 | 40.2% | 34.9% | 25.0% |
| Aug 2026 | 41.3% | 33.9% | 24.8% |
| Sep 2026 | 43.7% | 31.3% | 25.0% |
Retrofit: battery installed more than 90 days after the solar it is connected to. New and upgraded: battery installed within 90 days of a new solar system, or of a replacement, extension or addition to an existing one. Rows may not sum to exactly 100 because of rounding. September 2026 is the least complete month (see methodology). Source: CER, QCMR Q3 2026 data workbook, Figure 3.3.
Most batteries still go on to a roof that already had solar: add the retrofits to the batteries installed with upgraded solar and it was 62.8 to 68.7 per cent each month since May, against 70.2 to 76.5 per cent before. The regulator's workbook does not say why the mix moved, and we cannot tell from it whether households are choosing to do solar and battery together, or whether installers are selling them that way. What we can say is that the shift began in the month the taper began and has held for five months.
3. More than a quarter of rooftop solar jobs now replace an old system
A separate series in the same workbook measures what share of small-scale solar installations are recorded as replacements. In the September quarter of 2026 it was 27.4 per cent nationally, the highest share in a series the CER publishes from early 2021, when it was 9.8 per cent, on figures that can still change. A year earlier, in the September quarter of 2025, it was 22.6 per cent.
Queensland is highest, at 43.7 per cent of its installations in the September quarter, followed by South Australia (29.8) and Western Australia (28.4). New South Wales was 19.3 per cent and Victoria 12.7. The CER does not say what is driving the replacements, and the series does not show the age of the systems being replaced.
27.4%
of small-scale solar installations in the September quarter 2026 were replacements.
CER, QCMR Q3 2026 workbook, Figure 3.10 (not lag-adjusted)
43.7%
in Queensland, the highest of any state or territory in the quarter.
Same figure and source
15.3 GWh
of battery capacity installed and approved under the program to 30 September 2026, NSW 5.6 GWh of it.
CER, QCMR Q3 2026 workbook, Figure 3.1 (15,287.8 MWh)
What it means if you are getting a battery quoted
The regulator's figures do not tell you what size suits your house; that depends on your evening use, your tariff and your solar. They do show that the market has moved to the band where every kWh earns full or 60 per cent support. If your quote is for something over 28 kWh, each kWh from 28 to 50 now earns 15 per cent of the certificate rate, and above 50 the taper table lists nothing, so ask the installer to price a smaller option beside it (the tier arithmetic is here). And if your solar is ten or more years old and the quote replaces it as well, that is no longer unusual: between 22 and 25 per cent of batteries each month since May went in with replaced, extended or added-to solar, and more than a quarter of all solar jobs are now replacements. Get the solar and the battery priced separately so you can see what each part costs.