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Air-conditioners were working hard during the recent heatwave that affected large parts of Australia — and rooftop solar power systems did their bit to alleviate strain on the mains grid while making air-con use greener and cheaper.
From about 4.30AM last Monday January 5, 2026 to the same time this morning (January 12), rooftop solar contributed 18.8% to overall electricity demand in the National Electricity Market (NEM – QLD, NSW/ACT, VIC, SA and TAS) and Western Australia’s South-West Interconnected System (SWIS). Utility-scale solar kicked in another 10.3%.
The maximum contribution from rooftop solar systems installed in NEM regions was 46.9% on Monday, January 5 at 12PM, followed by 45.9% on Wednesday, January 6 at midday. Overall for the period, all renewables met 49.9% of demand.
Here’s what happened in each state and territory for the period (aside from NT – I don’t have figures) based on data sourced from Open Electricity:
Note: I originally recorded figures yesterday, then when checking them again this morning on Open Electricity, they were really off (much lower) for South Australia. So I’ve opted to use January 4 to January 11 figures originally recorded as they seemed to align better with what was happening when I was checking SA from time to time during that period. I’ll check the figures again in the coming days and adjust if necessary.
In a graph:
The period saw underlying NEM demand jump to a record high of more than 40,000 megawatts at one point and January 7-9 saw the highest electricity demand in the NEM during the January 5 – 12 period.
Hot summer days have been challenging for electricity networks, striking fear into the hearts of grid operators as high temperatures drive the increase use of air-conditioners.
But in part thanks to rooftop solar panel installations, Global Power Energy’s Geoff Eldridge said there were no Lack of Reserve notices, no calls for emergency reserves, and prices were largely stable in the middle part of the day. Wholesale spot prices even went negative at times, which is becoming increasingly common.
“Peak [underlying] demand is higher than it was in 2019, and summer heat remains a defining challenge,” he said. “What has changed is how the system absorbs that challenge. Solar now carries much of the heat-driven load during the day.”
The remaining challenge for summer is in the evenings, when panels are no longer producing power. But even that will become less of an issue in the years ahead thanks to the Cheaper Home Batteries program (CHBP). More than 175,000 home batteries have been installed since the program formally launched in July 2025. These batteries will serve their owners well, helping to power their homes during evening peak, and put downward pressure on wholesale power prices — benefiting everyone.
The week also would have been a good test of how home batteries cope with extreme heat.
Beyond home solar batteries, there are also plenty of utility scale energy storage projects being built — there seems to be project announcements every other day at the moment.
Another key element in taming the electricity system are Virtual Power Plants (VPPs). These are networks of distributed energy resources such as home batteries and solar panels centrally controlled by a third party and smart software to act as a single power source, balancing the grid and reducing peak demand.
But Virtual Power Plants are yet to really take off in Australia; even though we supposedly lead the world. Battery owners are still suspicious and concerned about various issues such as how hard a VPP operator might hit a battery and the impact that may have not only on battery warranty, but longevity.
According to this report from the Australian Competition and Consumer Commission (ACCC), around 38,200 Australian households were participating in VPPs by January last year, with adoption increasing nearly 22% every six months over the prior two-and-a-half years.
However, participation still trails well behind stand-alone battery installations. While there is a requirement under the CHBP that solar batteries installed be VPP *capable*, it is not required to join a program. But there can be added incentives for doing so. For example, In New South Wales and South Australia there is a payment available for connecting batteries to a VPP.
You can compare what’s available across Australia on SolarQuotes VPP comparison page.
By the way, you can also check out how rooftop solar performed on Xmas day 2025 here.
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Michael caught the solar power bug after purchasing components to cobble together a small off-grid PV system in 2008. He’s been reporting on Australian and international solar energy news ever since.
Denand Price
Our proerty is in SA and on the 10th (peak supply day), our system had the battery full by 13.15 and didn’t even start selling through Amber until 17.20 and the price was low enough that the battery wasn’t used at all to supply the grid. Amber income $1.34 for exporting 12.96 kWh
The 7th though, completely different story. We were selling power from the roof from 15.00 and from the battery by 19.00. Because of the demand from the grid, our battery only charged to 70% before the selling began. Amber income $33.99 for exporting 68.54kWh
FWIW the best income ( demand) during the heatwave was on Tues 5th, $205.14 from Amber for 76.03kWh of exports.
Not sure how this tallies up with the demand for exports to the grid.
Thanks, Michael. For keeping track of this information. Am I correct in saying that these percentages of solar contribution are only what reaches the grid and not the amount consumed behind the meter, that is directly from solar panels to air con? If that is correct the contribution of solar would be much higher. Is there anyway of measuring/estimating this.
that ia a good question, becuase at the distribution level (houses) dnsp monitoring is dark.
So, this implies they can measure solar self consumption. How do they do that?
Shirley this can only measure on front of the meter. We used 116KWh over that time period behind the meter (production minus export, almost exclusively on AC). Most solar owners with AC would be in a similar boat. (Although ymmv in specific KWh)
Air-conditioners were working hard during the recent heatwave that affected large parts of Australia — and rooftop solar power systems did their bit to alleviate strain on the mains grid while making air-con use greener and cheaper.
The global mean surface temperature anomaly for 1-8 Jan 2026, was +1.60 °C above the 1850-1900 reference baseline.
https://bsky.app/profile/climatecasino.net/post/3mc3ct5p2m22k
And this is apparently occurring during a weak La Niña phase.
4 Jan 2026: R-Niño3.4 at -0.95 °C
https://www.bom.gov.au/climate/enso/?ninoIndex=nino3.4&index=rnino34&period=weekly#overview-section=Monitoring-graphs
NOAA’s Jan 2026 ENSO update suggests a 50% chance of an El Niño phase by mid-2026 and more than 60% chance by 3Q-2026.
https://bsky.app/profile/climatecasino.net/post/3mbwdccptic2j
It seems air conditioners will likely be working much harder during the next even hotter Australian summer (i.e. 2026-27). Are you prepared?
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