The week of 28 June to 5 July delivered some of the sharpest price volatility we've seen in recent months, with South Australia the standout: SA1 swung from an average of $143/MWh (with a $840/MWh peak) on 29 June to a negative average of -$6/MWh on 2 July, including a trough of -$157.47/MWh. This whipsaw reflects a grid increasingly shaped by wind output that regularly exceeded 1,700 MW against comparatively modest overnight demand.
Tasmania was the other recurring story, posting 100% renewable generation on at least five separate days (29 June through 5 July) via hydro-wind combinations, yet simultaneously registering an extraordinary binding constraint (T_BLINK_TV_NGZ) with shadow prices between $7.3 million and $8.35 million on multiple occasions. The disconnect between abundant renewable supply and constraint-driven price movements in TAS1 is worth watching closely as it points to network limitations rather than generation scarcity.
Over in the west, WA1 trended firmer through the week, with daily averages climbing from $93/MWh on 28 June to a peak of $153/MWh on 3 July before easing back to $114/MWh by 4 July, punctuated by four distinct price spikes. Meanwhile NSW1 and QLD1 experienced more moderate conditions, though both recorded brief negative pricing episodes tied to solar oversupply.
SA1 was the most volatile region on the NEM this week, ranging from a low of -$157/MWh (2 July) to a high of $840/MWh (29 June) — an enormous spread reflecting the region's wind-dominated generation mix and thin demand overnight. VIC1 also saw notable swings, with average prices collapsing to $8/MWh on 2 July and $16/MWh on 1 July amid high wind output, before recovering to $64/MWh by 4 July. NSW1 held a steadier band through the week, averaging between $60/MWh and $121/MWh, while QLD1 stayed relatively contained between $50/MWh and $101/MWh.
WA1 was firmer and more volatile than usual this week, averaging $93–$153/MWh across the period with four distinct price spikes: $250.39/MWh on 30 June, $278.66/MWh on 2 July, $276/MWh on 3 July, and a sharp $335.18/MWh spike on 5 July — a 71% jump from the prior interval before prices stabilised. Each event was isolated to one or two trading intervals, suggesting short-lived supply-demand tightness rather than sustained scarcity.
Tasmania achieved 100% renewable generation on repeated occasions across the week (29 June, 1–5 July), with hydro output ranging from roughly 890 MW to 1,571 MW and wind contributing between 42 MW and 282 MW depending on conditions. South Australia posted several high-renewable-penetration intervals, including 95.7% on 1 July and 95.3% on 2 July, both driven by wind generation exceeding 1,690 MW. These periods of high renewable output frequently coincided with negative or near-zero pricing across SA1, VIC1 and TAS1, indicating genuine oversupply conditions rather than curtailment constraints in most cases — with the notable exception of Tasmania's recurring network constraint discussed below.
Gas hub prices held a narrow, stable band through the week. STTM Adelaide ranged $11.00–$11.75/GJ, STTM Sydney $10.96–$11.50/GJ, and STTM Brisbane $11.07–$11.68/GJ, with no material directional movement. DWGM Victoria was slightly softer, trading between $9.75/GJ and $10.50/GJ.
Certificate markets were more eventful. LGC prices continued their strong run-up from $2.90 in late March to a peak of $8.50 for the week ending 26 June, before easing back to $7.00 for the week ending 3 July — a pullback worth monitoring as the market digests the recent rally.
Expect continued volatility in SA1 and VIC1 as wind generation remains the dominant swing factor, with negative pricing likely to recur during periods of strong wind output paired with soft demand. Tasmania's recurring network constraint bears watching — if it persists, it may continue to decouple regional prices from underlying renewable abundance. In the west, WA1's recent run of price spikes suggests demand-side tightness worth monitoring into the coming week. Gas hub prices are likely to remain range-bound, while the LGC market's pullback from its late-June peak will be one to watch for signs of stabilisation or further correction.
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