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Western Australia's wholesale electricity price set a record in the June quarter. The average real-time energy price on the Wholesale Electricity Market reached $117.87/MWh, up $27.41 or 30 per cent on the same quarter last year.
Over the same three months the eastern states went the opposite way, with the National Electricity Market falling 47 per cent to around $74/MWh.
Two grids, one country, opposite directions. That divergence is the story, and it is worth understanding properly before anyone turns it into a sales line, including us.
Changes in the generation mix
The record was not caused by demand. Underlying WEM demand rose 1.6 per cent year on year, which is ordinary.
The supply side did the work. Coal generation fell 137 MW, down 17 per cent, with the retirement of Muja C Unit 6 in the second quarter of 2025 in that number. Wind fell 54 MW, down 13 per cent, largely through outages tied to the Warradarge expansion. Something had to cover both, and gas did, lifting its share of generation by 8.30 percentage points while coal dropped 6.11 points and wind dropped 2.48.
Gas sets the price when it is on the margin, and it sets it high.
The uncomfortable corollary is one you will not see on many solar company websites: Western Australia's renewable share went backwards this quarter, from 33.6 to 32.0 per cent. Distributed rooftop PV output rose 3.4 per cent, so households and businesses kept adding generation. It was not enough to offset a coal unit leaving and a wind farm being out.
Normalised WEM costs came in at $175.53/MWh, up $31.87.
Wholesale prices and residential tariffs
This is the part to get right, because the temptation to draw a straight line from "record wholesale prices" to "install solar now" is strong and the line does not exist.
Synergy's residential tariffs are set through government price-setting, not by what the wholesale market did last quarter. The Home Plan A1 rate moved to 33.26 c/kWh on 1 July 2026, up 2.75 per cent from 32.37 c/kWh, with the daily supply charge at 119.24 c/day. That 2.75 per cent bears no resemblance to a 30 per cent wholesale move, because it was never going to.
A residential customer in Perth is insulated from the quarter's wholesale record in a way a business on a contestable contract is not. If you are large enough to buy energy contestably, your exposure is real and your renewal is where you will meet it. If you are on a standard residential tariff, the effect reaches you slowly, through the price-setting process, over years.
Both are reasons to look at solar. They are not the same reason, and they do not carry the same urgency. Anyone selling you a residential system this month on the basis of a wholesale number is selling you a correlation that does not connect. If you are the business on the contestable contract instead, the 1 MW commercial rebate change is the more relevant read.
Household storage in WA grew 39 per cent in a quarter
The more directly useful number in the report is what WA households did.
Household storage capacity on the WEM rose 288 MWh over the quarter, up 39 per cent, reaching 1,027 MWh. Installations rose by 11,823, up 33 per cent, taking the state past 47,000 systems. Those figures come from Clean Energy Regulator data current to 30 June 2026.
Crossing a gigawatt-hour of household storage in Western Australia is a genuine threshold. It also happened in a single quarter of growth, which tells you the WA Residential Battery Scheme and the federal program are doing exactly what they were designed to do.
What it does not tell you is what those batteries are doing to the grid, because the WEM data does not break that out.
Evening-peak evidence from the NEM
AEMO did publish household battery behaviour this quarter, and it is worth reading with the caveat attached.
The analysis compared two samples of 10,000 detached dwellings each, all with rooftop PV under 20kW, with the battery group installed between 1 July and 1 December 2025. Across the evening peak, defined as 1600 to 2100 hours, homes with a battery drew 0.7 kW less from the grid on average. That is a 73 per cent reduction in net imports across the peak window. By region it ran 0.9 kW in Queensland, 0.7 kW in New South Wales, and 0.5 kW in both Victoria and South Australia.
That is a strong result and it is the clearest published evidence to date that residential batteries shift the evening peak rather than just shifting a household's bill.
It is also entirely National Electricity Market data. Western Australia is not in that sample, and the SWIS is a different system with a different demand shape, a different generation mix, and a different summer. Do not let anyone quote the 73 per cent figure at you as a WA number. The behaviour is likely directionally similar here. The magnitude is unmeasured.
Storage sizing for evening demand
The practical read for a Western Australian site is straightforward, and it has not changed because of one quarter.
Gas on the margin at a high price means the expensive hours are the hours after the sun goes down. That is the same conclusion the evening-peak data reaches from the other direction. A system designed to maximise daytime generation and export, on a grid that pays little for that export and charges a lot for the evening, is optimised for the wrong half of the day.
Sizing to your load profile means looking at your 4pm to 9pm consumption and building storage against it, rather than filling the roof and hoping. For a household with ducted aircon and an EV that is a meaningful battery. For a household that is empty until 7pm and cooks on gas, it is a smaller one than most quotes assume, and we will tell you that.
If you want your consumption profile read properly before anyone specifies equipment against it, get a quote and bring twelve months of interval data.
Sources
- AEMO, Quarterly Energy Dynamics Q2 2026. WEM price and generation-mix figures at executive summary p5 and p65; NEM household battery analysis at p11-12
- Clean Energy Regulator data on WA household storage, current to 30 June 2026, as reported in the AEMO Q2 2026 report
- Synergy Home Plan A1 tariff and supply charge from 1 July 2026