AEMO measured what a home battery does to your evening peak: 73 per cent less grid power

This site has covered what a battery is worth on your bill and how fast Australians are buying them. What has been missing is the physical middle of that story: what the thing actually does, hour by hour, in real houses. AEMO has now published it.

What the meters showed

The two sample groups were built to be comparable: detached houses with rooftop systems under 20 kW, and for the battery group, only batteries installed between 1 July and 1 December 2025. That matters, because it means the battery homes had been running their systems for at least one full season before the quarter measured.

Three differences showed up in the daily shape. Battery households transitioned to net exports later in the morning than PV-only households, because they charge the battery before sending surplus to the grid. Through the evening peak they continued exporting for longer and recorded lower net grid imports than PV-only households. And the reduction in what they took from the grid at that peak was the 0.7 kW figure above, which AEMO describes as equivalent to 73% reduction relative to PV-only households across the quarter.

The practical translation: through the hours when electricity is most expensive to supply, and when most people are cooking and heating, a battery household is close to invisible to the grid.

It is now big enough to see from orbit

The individual effect is one thing. The aggregate is what makes this quarter notable. AEMO reports that demand across the market grew in daytime hours as increased home battery charging, industrial demand and data centre load outpaced distributed PV output growth, and that this reshaped the daily demand profile, with demand shifting away from the evening peak as more home batteries supplied household consumption after sunset.

Read that twice, because it is a genuine turn. For a decade the story of rooftop solar was what it did to the middle of the day. The story of home batteries is what they are doing to the evening, which is the part of the day the grid was built around and the part that sets what everyone pays for network capacity.

The wholesale price fell 47 per cent. Your bill will not.

Over the same quarter, NEM-average wholesale spot prices averaged $74/MWh, down $66/MWh (-47%) from Q2 2025, and the lowest Q2 average since 2020. AEMO attributes that to more renewable generation, more grid-scale battery discharge in peak periods, and reduced evening peak demand. The renewable share of generation hit a new Q2 high of 42.1 per cent, coal fell to a new Q2 low, and gas-fired generation recorded its lowest Q2 average since 2003.

Our view, and it is a caution rather than a finding. A 47 per cent fall in the wholesale price is not a 47 per cent fall in your bill, and you should be sceptical of anyone who implies it is. Wholesale energy is only part of a retail bill, the rest being network charges, environmental schemes and retail margin. Retail offers and the default price are set on trailing periods, so a quarter like this one shows up late if it shows up at all, and only if the next quarters look similar. What this quarter does say is that the direction is favourable and the reasons are structural rather than weather luck.

One number worth watching next

Grid-scale batteries, the industrial cousins of the one on your wall, moved from setting the wholesale price in 17 per cent of dispatch intervals in Q2 2025 to 36 per cent this quarter, with daytime charging up 211 per cent and evening discharge up 228 per cent year on year. Household batteries and grid batteries are now doing the same job at two very different scales, and between them they are the reason the evening peak is flattening.

Sources

1. AEMO, Quarterly Energy Dynamics Q2 2026 (PDF, 91 pages, published July 2026, downloaded 3 August 2026): the household PV and battery metering comparison and the 0.7 kW and 73 per cent figures, the regional breakdown, distributed PV output, the demand-profile commentary, wholesale prices, renewable share, coal and gas generation, and the grid-scale battery price-setting figures.
2. AEMO, Quarterly Energy Dynamics: the report series landing page.
3. The Electric Household, The ACCC did the sums on home batteries: what a battery is worth on an annual bill.
4. The Electric Household, Home batteries are outpacing new solar: how quickly they are being installed.

Methodology. Every figure is from AEMO’s Quarterly Energy Dynamics Q2 2026, covering 1 April to 30 June 2026 and published in July 2026; we downloaded the 91-page PDF on 3 August 2026 and read it rather than a summary of it. The household comparison is AEMO’s own, from National Metering Identifier sample datasets of 10,000 households in each group, detached dwellings with installed PV under 20 kW, and for the battery group only systems installed between 1 July and 1 December 2025; the evening peak is AEMO’s definition of 1600 to 2100 hours. We have not verified the sampling independently, and detached houses with sub-20 kW systems are not every household. The 0.7 kW figure is a quarterly average, not a promise about any one home, and it measures grid imports avoided rather than money saved, which depends on your tariff. The paragraph about retail prices is labelled as our view, not AEMO’s.

Have a battery and read your own data differently? Tell us and we will check it against the report and log the outcome here.