​On Wednesday evening, 8 July, Victoria electricity price reached $19,070/MWh, just below the market price cap of $20,300/MWh. South Australia followed closely, peaking at $16,971/MWh.

The spike came as record winter demand coincided with a drop in wind generation to 10% of normal. Gas, coal and hydro generators stepped in to fill the gap, while batteries could only cover a fraction of the shortfall.

South Australia's highly renewable grid is known for its sensitivity to high demand and low wind conditions. Victoria is increasingly showing the same characteristics. Together, the southern states are becoming more exposed to weather-driven price volatility, while New South Wales and Queensland remain relatively insulated thanks to their generation mix and milder winter conditions.

This article explains what drove the 8 July price event, how batteries responded, and why Victoria and South Australia are increasingly experiencing these extreme price outcomes.

Executive Summary

• Victoria's daily average price reached $359/MWh on Wednesday 8 July, with an evening peak of $19,070/MWh. South Australia averaged $336 and peaked at $16,971.
• Victorian evening demand was 26% above the quarterly average while wind generation fell 94% below normal. South Australia could not provide relief, with demand running 9% above average and wind generation 81% below its benchmark.
• Pre-dispatch signalled the price spike an hour early, causing some batteries to discharge before prices peaked.
• Weather-driven volatility is becoming increasingly important for battery revenues. As standard spreads are cannibalised, extreme system events are carrying a larger share of battery value, particularly in Victoria and South Australia.

Wind ran at 10% of normal, coinciding with elevated heating demand

A slow-moving high-pressure system brought cold temperatures, fog and exceptionally light winds across south-eastern Australia. That combination pushed heating demand higher while suppressing both wind and solar generation.

Victoria recorded winter demand of around 9 GW on 7 July. Although demand eased slightly on 8 July, it remained above 8 GW through the evening—around 26% above the quarterly average. At the same time, wind generation collapsed to just 6% of its normal evening output.