The week of 10–17 May 2026 delivered a broadly mixed picture across Australia's electricity markets. NEM regions traded in relatively moderate ranges through the early part of the week before a notable softening across eastern mainland markets mid-week — particularly on 15 May, where Victoria averaged just $35/MWh and South Australia $40/MWh as renewable output ran strong and demand remained subdued in the autumn shoulder season. Tasmania was the exception, holding firmer averages of $92–$104/MWh throughout the week, underpinned by consistent hydro dispatch and a series of significant transmission constraints on the Basslink interconnector.
The Western Australian Wholesale Electricity Market (WEM) told a markedly different story. WA1 averaged well above NEM mainland levels for most of the week, with daily averages climbing from $88/MWh on 10 May to a peak of $172/MWh on 15 May, punctuated by multiple sharp intraday spikes. The contrast between WEM and the softer NEM mainland conditions was one of the defining features of the week, reflecting differing demand profiles, generation mix, and the WEM's structural isolation from eastern market dynamics.
Monday morning (18 May) data captured in the daily narratives shows the NEM morning ramp in full effect, with NSW printing $244.54/MWh at 7,619 MW, SA at $204.94/MWh, and QLD at $214.07/MWh — a reminder that the shoulder-season softness observed mid-week can reverse sharply during peak morning load periods. The QNI interconnector was binding at its import limit of approximately -189 MW, with Queensland drawing from NSW as the morning ramp gathered pace.
Mainland NEM prices were broadly moderate across the week, with a pronounced mid-week dip. Key regional highlights:
WA1 was the most consistently elevated market this week. Daily averages rose steadily from $88/MWh on 10 May to $172/MWh on 15 May before easing slightly to $160/MWh on 16 May. Multiple sharp intraday spikes were recorded across the week, including a major event on 12 May where prices surged to $689/MWh across two consecutive five-minute intervals — a more than fourfold jump from the preceding price level. Additional moderate spikes in the $251–$263/MWh range were recorded on 14, 15, and 16 May, predominantly in isolated single-interval events during morning and evening periods. Price floors in WA1 remained well above NEM mainland levels throughout, with daily minimums no lower than $57/MWh.
Tasmania was the standout for renewable generation performance this week. The state recorded 100% renewable penetration on multiple occasions — including on 11, 12, 13, 14, 15, and 16 May — with hydro and wind collectively meeting all dispatched demand during evening periods. On 16 May between 17:35 and 18:00, Tasmania operated at exactly 100% renewables, with hydro and wind combining for full system coverage at prices of $88–$97/MWh. By 17 May, TAS1 reached 95.2
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