The week of 19–26 July delivered a study in contrasts between the NEM and WEM. Across the eastern states, spot prices eased steadily as the week progressed, with VIC1, TAS1 and QLD1 all trending into the $20-40/MWh average range by 23-25 July, supported by strong wind, hydro and solar output overnight and into the shoulder periods. Negative pricing became a near-daily feature across NSW1, VIC1, SA1, QLD1 and TAS1, typically clustered in the overnight and pre-dawn window when renewable generation outpaced demand.
The WEM told a different story entirely. WA1 held elevated average prices all week — ranging from $117/MWh to $155/MWh daily — and recorded five separate price spikes above $250/MWh, including a peak of $388.19/MWh on 21 July and $382/MWh on 22 July. This reflects the WEM's distinct supply-demand dynamics, where evening peak periods with minimal wind and solar contribution continue to produce sharper price responses than the interconnected NEM.
Overall, it was a week where mild eastern-state conditions and abundant renewable supply kept NEM prices in check, while WA1 conditions remained comparatively tight and volatile — a reminder that the two markets can move on very different trajectories in the same week.
WA1 was the standout region for price tension this week, averaging $117-$155/MWh daily — well above every NEM region bar none. Moderate-to-major price spikes were recorded on 20 July ($308.95/MWh and $257.34/MWh), 21 July ($252.50/MWh), 23 July, and 24 July ($267.62/MWh and $252.50/MWh), generally during evening peak or morning ramp periods with limited wind and solar contribution. The 21 and 22 July trading days also produced maximum prices of $388/MWh and $382/MWh respectively, underscoring how quickly WA1 pricing can move when reserve margins tighten.
Tasmania was the renewable story of the week, recording high renewable penetration on six separate occasions — peaking at 92.7% on 23 July and 92.0% on both 24 and 26 July, with combined hydro and wind output ranging from roughly 1,433 MW up to 3,878 MW depending on the evening. Interestingly, several of these high-renewable evenings coincided with rising rather than falling prices — TAS1 climbed from $68.14/MWh to $100.24/MWh on 26 July despite 92% renewable supply, illustrating that penetration percentage alone doesn't guarantee price softness when system constraints are active.
South Australia also posted a notable renewable evening on 21 July, reaching 88.0% penetration with wind contributing 762.3 MW, while prices remained in a moderate $29.65-$69.27/MWh band — an example of the system comfortably absorbing high renewable output. Across the broader NEM, high solar output (frequently 5,000-8,000 MW combined across regions) was the recurring driver behind the week's negative pricing events, particularly in QLD1's pre-dawn and early morning windows.
The standout structural event this week was a recurring binding constraint in TAS1 — T_BLINK_TV_NGZ — which registered an exceptionally high shadow price of $8,352,000/MWh on three separate occasions (22, 23 and 25 July), each time during the early morning period. Despite the extraordinary shadow price, wholesale outcomes during these windows were mixed: prices ranged from deeply negative (-$4.59/MWh) through to modestly positive ($11.35/MWh), suggesting the constraint was shaping dispatch patterns without necessarily driving extreme spot outcomes on its own.
On the WEM side, the five price spikes noted above in Price Trends represent the week's most material events, with the 20 July spike to $308.95/MWh classified as major. FCAS markets were quiet by comparison — weekly average prices across all eight services remained low, topping out at $2.70/MWh for RAISEREG and $0.91/MWh for LOWERREG, with no material spikes recorded in any contingency or regulation service this week.
Gas hub prices held in a fairly narrow band across the week. STTM Brisbane was the firmest hub, easing slightly from $11.90/GJ on 21 July to $11.55/GJ by 26 July. STTM Sydney tracked between $10.99/GJ and $11.25/GJ, while STTM Adelaide ranged from $10.90/GJ to $11.45/GJ. DWGM Victoria was the softest of the four, sliding from $10.47/GJ on 23 July to $10.00/GJ on 24 July — the last day reported.
Certificate markets showed renewed upward movement, with LGC prices lifting to $5.85 for the week ending 24 July, up from $5.05 the previous week. This follows a volatile run over the past two months — from a low of $3.50 in early June through to a peak of $8.50 in late June — indicating the LGC market remains sensitive to shifting supply and compliance-period dynamics.
With renewable output remaining strong across Tasmania, South Australia and Victoria, expect further negative pricing episodes during overnight and shoulder periods in the NEM, particularly if mild demand conditions persist. The recurring TAS1 constraint is worth monitoring for continuation into the coming week. On the WEM, sustained elevated averages and repeated spikes above $250/MWh suggest WA1 conditions remain tight — a pattern likely to persist barring a material shift in generation availability or demand. Gas hub prices should stay range-bound, while the LGC market's recent bounce warrants continued attention as the certificate market works through supply dynamics heading into the back half of the year.
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