May typically sees consumption rise from the April low as colder weather blows in. Wind generation typically increases by about 15% during this period, often climbing to yearly highs that have fallen anywhere from June to September in recent years. Solar output declines, particularly in the southern states where seasonal variation is greatest.

In 2026 this was especially the case, with solar generation in both Victoria and South Australia falling below last May’s levels, despite over 400 MW of utility-scale solar and substantial rooftop capacity added. Regardless, the NEM saw reduced gas and black coal generation, offset by substantially higher wind output than last year.

May's end also marked the end of autumn, typically a quieter period for the NEM. Autumn combines lower solar generation than summer with weaker wind output than winter and spring – with fossil generation muted due to reduced demand. This is the general pattern, but the story varies considerably between states. Queensland, for instance, saw more coal generation in autumn than summer in the years 2022–2025, a trend broken this year with a decline of over 4%.

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New South Wales recorded 111 GWh of battery discharge in May, an 18% increase on the previous record of 94 GWh set just a month earlier in April. This marks the sixth consecutive month that NSW has broken its monthly battery discharge record. The first month of this streak, December 2025, recorded just 43 GWh – less than half the current monthly figure. NSW is also the second state in the NEM to achieve 100 GWh of battery discharge in a calendar month, with Queensland having reached the milestone in April, and the WEM achieving the figure in December last year.

This growth is driven primarily by the completion of several large batteries. While over 3 GWh of storage has commenced since December, the largest growth has come from batteries that began operation earlier, with over 70 GWh of discharge from three batteries (Eraring, Waratah Super Battery and Limondale), each having commenced prior to December.

NSW also passed another battery milestone in May, becoming the first state to surpass its entire 2025 battery discharge total.

In 2025, NSW batteries discharged a total of 282 GWh, a figure eclipsed on 2 May this year. On this day, NSW batteries discharged over five times more than the same date last year, with the 2025 figure at just 50 GWh.

Queensland broke its record for the highest wind generation in a day on the 12th of May, registering 32,242 MWh, and surpassing the previous high set in January this year.

Across the NEM, wind records most often fall in winter and early spring. Each monthly high since 2017 has occurred from June to September, reflecting the fact that most installed capacity is in the southern states, where wind conditions are generally strongest in that period.

Queensland is slightly different. While it also experiences strong winter winds, its records have more often broken in the period preceding the southern pattern. Previous wind records in Queensland have fallen in May during five of the past seven years.

The record generation on 12 May is a particularly dramatic instance of this, with northern NSW and Queensland seeing especially strong conditions, while Victoria and South Australia saw low generation even by May standards. Even the Macintyre Wind Farm – the still-commissioning Acciona facility that is destined to become the southern hemisphere’s largest wind farm – saw a substantially greater capacity factor than many facilities across the southern states.

On the 15th of May, batteries charged for a total of 18,585MWh, 26% higher than the record standing prior to this month. The 15th also featured the monthly record being broken in NSW, Victoria and Queensland.

Previous records have often been driven by a single large battery having an outsized effect on NEM or state activity. For example, the Eraring battery drove the previous record in December, comprising over a quarter of the country's battery charging activity – equivalent to about two cycles in a day.

The 15 May activity, by contrast, reflected a more distributed increase in battery capacity. 5.4 GWh of storage has been added since December. Eraring was again the largest contributor, but at only 10% of the NEM total.

While not featuring in formal records, several other battery-related phenomena caught our attention in May. Despite the high battery activity, 15 May saw relatively low price variation – similar to events earlier in the month in NSW specifically. 18 May attracted attention for some of the worst renewable conditions in recent years. This created unusual circumstances for batteries, which charged at high prices during the day before an expected evening price spike failed to materialise.

Finally, battery discharge has exceeded OCGT generation nationwide over the last 12 months. In the 12 month period from June 2024 to May 2025, batteries generated just 860 GWh, compared to 3,274 GWh from OCGT. Over the following year, battery discharge more than tripled. The fall in OCGT was concentrated in Queensland, which accounted for 500 GWh of the 593 GWh decline across the NEM.

While gas in other states is often called on irregularly during extended renewable lulls, Queensland’s gas peakers tend to run more predictably each day. This makes their role easier for batteries to replace.

Western Australia has seen its lowest daily coal generation, with just 6,565 MWh generated on 8 May, narrowly below the 6,573 MWh generated on 11 April this year.

The WEM is structurally different from the NEM, with both coal and gas playing major roles in the generation mix. Queensland – the largest gas-generating state of the NEM states with coal generation – met only around 5% of its demand with gas over the last 12 months. 

By contrast, gas supplied around 30% of electricity demand in WA. That matters for how coal operates. WA’s flexible generation from gas, and increasingly batteries, can absorb more of the variation in demand and renewable output across the day. As a result, coal generation can remain remarkably stable, in a way that is rarely seen in the east coast market, especially from black coal facilities.

The WA government aims to decommission the state’s two coal-fired power stations by 2030, with the remaining Bluewaters power station scheduled to also shut down in 2030. Based on current facilities under construction, the coal shutdowns – if they proceed as planned – will likely be supported by increased output from existing facilities. This is also the explanation for the recent coal low.

Coal generation has decreased substantially since May last year, with much of this decline replaced by gas. While three wind projects are under construction with capacity close to 30% of the current state total, no solar or wind projects have commenced since August 2024. Utility-scale renewable generation has increased nonetheless, though variations likely reflect changing conditions or reduced curtailment. The May decline is entirely replaced with increased gas.

OX2 has commenced construction on its Muswellbrook solar farm and battery facility. The 135 MW solar farm and 158 MW / 316 MWh battery are expected to commence operation in 2028. This brings the total solar capacity under construction in NSW to 1.4 GW. While OX2 has developed projects previously, this is the first project that will be both owned and operated by OX2 in the NEM.

Edify has reached financial close for the Smoky Creek and Guthrie’s Gap projects. Together, they total 600MW of solar and 600MW/2400MWh of battery capacity. This brings Queensland to over 12GWh of battery storage either commenced or under construction, the second highest in the NEM. The projects are expected to come online in 2029.

The Woolooga BESS commenced on 26 May. Construction of the 222 MW / 593 MWh battery began in December 2024, years after the solar farm's completion in 2022.

While Lightsource BP has completed numerous solar farms, this is the company's first battery to commence operation. The company’s Goulburn River BESS is under construction, with Lower Wonga the next likely to commence construction later this year.

Flow Power’s Bennetts Creek BESS is the first battery to begin construction in Victoria this year. Having reached FID in late 2025, the 100 MW / 200 MWh battery is expected to commence operation in 2028. The facility is located south of Morwell, one of now four batteries in close proximity to one another and the retired Hazelwood and Energy Brix coal-fired power stations.

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See all records and the latest facilities updates at Open Electricity.

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