This note compares NEM prices across five financial years, FY22 to FY26, to find which parts of the price distribution changed and which did not.
- The fall in spikes is a fall in small spikes. Spike episodes fell 84%, but episodes reaching $5,000/MWh fell 74%, so their share of episodes rose from 3.3% to 5.4%. New South Wales had about as many in FY26 as in FY22.
- More of the largest spikes arrive without warning. In FY26, 53% of episodes reaching $5,000 were already at $5,000 in their first interval, the highest of the five years (40 episodes, so the interval is wide).
- Negative prices became common while the floor almost disappeared. Intervals below $0 rose to 13–32% in four regions, while prices at the −$1,000 floor fell from up to 0.06% of intervals to at most about 0.01%.
- Night-time spikes disappeared in New South Wales and Queensland. Onsets between midnight and 5 am fell to almost none, and 51–68% now start between 4 pm and 8 pm. South Australia's onsets are still spread across the day.
Two changes are well known and serve here as context: FY22 included the 2022 gas and coal supply crisis, and median midday prices in the solar-heavy regions are now below zero (Fig. 5).
The data are AEMO's 5-minute dispatch prices for all five regions, from 1 October 2021 to 31 May 2026. FY22 therefore covers 273 days, from October 2021 to June 2022, and FY26 covers 335 days, from July 2025 to May 2026; counts are normalised to 30 days. A spike episode is a run of consecutive 5-minute prices above $300/MWh in one region, and its onset interval is the first price above $300. There are 12,794 episodes. Shares of intervals exclude the June 2022 market suspension and intervals under administered pricing, when prices were set by rule.
change in spike episodes per 30 days, five regions pooled, FY22 → FY26 (418 → 66).
of South Australia's 5-minute intervals were below $0 in FY26 (18% in FY22).
of FY26 episodes reaching ≥$5,000/MWh had an onset interval already ≥$5,000 (21 of 40).
Spike episodes fell 84% from FY22 to FY26, and by 68–94% in each region
Across the five regions, spike episodes fell from 418 per 30 days in FY22 to 66 in FY26, a drop of 84%. The decline was largest in Queensland, from 139 to 8 per 30 days (−94%). Tasmania fell 91% and Victoria 88%. New South Wales fell 76%. South Australia fell least, 68%, from 96 to 31 per 30 days, and remains the region with the most episodes.
Interpretation. The data record the decline but do not identify its causes. Candidate contributors over this period are battery capacity that can respond within one 5-minute dispatch interval, more wind and solar generation, and the end of the 2022 supply crisis. For Queensland, our earlier analysis of fundamentals found median wind output four times higher and spare generating capacity 53% higher in 2026 than in 2022.
The largest spikes fell least: episodes reaching $5,000 rose from 3.3% to 5.4% of all episodes
Episodes whose price reached at least $5,000/MWh fell from 14.0 to 3.6 per 30 days across the five regions. That is a 74% decline, against 84% for all spike episodes. The share of episodes reaching $5,000 therefore rose: 3.3% in FY22, 2.4% in FY23, 3.2% in FY24, 6.3% in FY25 and 5.4% in FY26.
The regions differ. New South Wales recorded about the same number of episodes reaching $5,000 in FY26 as in FY22 (1.9 and 2.0 per 30 days), so their share of its episodes rose from 3% to 12%. Queensland's fell from 6.8 to 0.2 per 30 days. Victoria recorded none in FY26.
Interpretation. Whatever reduced the number of small episodes did not reduce the largest ones at the same rate. That is consistent with the largest events being set by conditions that fast short-duration resources cannot fully offset, such as unit outages, network constraints or sustained evening shortfalls. The data here do not test those mechanisms.
53% of FY26 episodes reaching ≥$5,000/MWh had an onset interval already ≥$5,000 (n = 40)
For each episode that reached $5,000/MWh we recorded two things. The first is whether its onset interval was already at or above $5,000. The second is whether its first interval at or above $1,000 was also at or above $5,000. In FY26, 21 of 40 such episodes (53%) began at ≥$5,000, and 32 of 40 (80%) went from below $1,000 to ≥$5,000 in a single interval.
FY26 has the highest values of the five years on both measures. The sample is small, however, and the 90% interval for the first measure runs from 40% to 65%. The series is also not a steady trend: FY22 recorded 42%, and FY24 27%.
Interpretation. In an episode that starts at ≥$5,000, the price series provides no intermediate interval that could serve as a warning. Anticipating such episodes requires information from outside the price history, such as the operator's pre-dispatch forecast, unit availability and network constraints.
Prices below $0 rose to 13–32% of intervals in four regions, while prices at the −$1,000 floor almost disappeared
The share of intervals below $0 rose in four regions. In South Australia it went from 18.1% to 32.3%, in Victoria from 13.6% to 27.4%, in Queensland from 3.1% to 18.7%, and in New South Wales from 1.8% to 12.9%. Tasmania, which is mostly hydro, shows no trend (2.7–6.7%).
The share of prices at exactly $0 roughly doubled, to 1.2–2.1% of intervals in four regions. The share at or near the −$1,000 market floor (≤ −$999) did the opposite. It was 0.03–0.06% of intervals in South Australia in FY22–FY23 and in Queensland in FY22. From FY24 it has been at most about 0.01% in every region.
Two earlier analyses agree. In the first, South Australia's price distribution first showed a separate negative-price mode in 2020; Victoria followed in 2021, and New South Wales and Queensland in 2023. That is the order of their solar uptake. In the second, the chance that a negative price in South Australia reached the floor fell from 8.3% to 0.004%. South Australia recorded 311 intervals at the floor in 2019, and none in 2023 or 2025.
Interpretation. Negative prices occur when midday rooftop and utility solar output, plus inflexible generation, exceeds regional demand and export capacity. Generators whose revenue is tied to output, through renewable certificates or contracts, can offer below $0 and still earn money. The fall in floor prints while negative prices became common is consistent with battery charging and other flexible demand absorbing surplus before the price reaches −$1,000.
Figure 5 places these hours in the day: the median 5-minute price for each hour, one line per financial year. South Australia's 11:00–14:00 median was +$3 in FY22, between −$24 and −$33 from FY23 to FY25, and −$9 in FY26. Its highest hourly median, in the evening, was $120, $181, $138, $138 and $107 in those years. Victoria's midday median has been below $0 since FY24, as has Queensland's. New South Wales' midday median fell from $72 to $11 and stays above zero. Tasmania has no midday dip.
In the solar-heavy regions, solar output now sets the daily price profile. Prices are lowest when solar output is highest, and highest at the evening ramp, when solar output falls and demand peaks. The spread between the two is the opportunity that battery charging at midday and discharging in the evening exploits. FY26's less negative midday median in South Australia is measured, but its cause is not identified here.
Night-time spike onsets have disappeared in New South Wales and Queensland; South Australia's are still spread across the day
Each row of the figure is one financial year. Each cell is the share of that year's spike onsets in each hour of the day.
In New South Wales, the share of onsets between midnight and 5 am fell from 17% in FY22 to none in FY25 and FY26. The share between 4 pm and 8 pm rose from 19% to 51–68% in FY24–FY26. The single hour from 5 pm to 6 pm went from 5% of onsets to 21–34%. Queensland followed the same pattern: night-time onsets fell from 13% to 0–3%, and 4–8 pm rose from 28% to 60–67%.
South Australia did not shift toward the evening. From FY22 to FY26, 26–37% of its onsets fell between 4 pm and 8 pm, 14–19% between 6 am and 9 am, and 10–20% between midnight and 5 am.
Interpretation. In New South Wales and Queensland, spike risk now coincides with the evening net-demand ramp, when solar output falls away. South Australia's onsets remain spread across the day. That is consistent with wind variability and the limits of its interconnection with Victoria driving more of its spikes. The figures here do not test those causes.
Record prices track the administered price cap, which rose 34% over the period
The market price cap was $15,100/MWh in FY22, $15,500 in FY23, $16,600 in FY24, $17,500 in FY25 and $20,300 in FY26: 34% higher over the period. The FY26 step alone was 16%. In 22 of the 25 region-years, the year's highest 5-minute price was exactly the cap. The exceptions are Victoria in FY23 ($14,633), Queensland in FY26 ($19,728) and Victoria in FY26 ($3,026; no episode reached $5,000 there that year).
An earlier record-statistics analysis of South Australia and New South Wales found the same pattern back to 2019. Every new record-high price since then has equalled the cap in force that year. The highest prices are set by the administered cap, not by a price that the market discovers.
Interpretation. The cap is administered: it is set in advance for each financial year and adjusted for inflation. The FY26 step of 16% is larger than recent annual inflation, which implies a scheduled increase on top of indexation. Because the cap binds at the top of the distribution, raising it raises the dollar value of every cap-level interval, whatever the physical conditions.
Summary of measured changes, FY22 to FY26
Spike episodes above $300/MWh fell 84% per 30 days across the five regions, and by 68–94% in each region.
Episodes reaching ≥$5,000/MWh fell 74%; their share of all episodes rose from 3.3% to 5.4%. In FY26, 53% had an onset interval already ≥$5,000 (n = 40).
Intervals below $0 rose in four regions, to 32% in South Australia and 27% in Victoria. Prices at the −$1,000 floor are now close to zero.
Median midday prices are below $0 in three regions. In NSW and Queensland, 51–68% of spike onsets now occur between 4 pm and 8 pm.