WA MARKET UPDATE
Electricity Prices
In September 2025, we observed continued volatility in Western Australia’s electricity market, driven by both supply and demand factors. Wholesale prices remained elevated, influenced by network constraints, periods of lower wind and solar generation, and maintenance at key thermal plants. While gas and coal-fired stations provided reliable baseload supply, fluctuations in renewable output contributed to short-term price spikes across the month.
Generation Mix
Western Australia’s electricity generation came from a combination of gas, coal, wind, and solar. Renewables contributed around 30–35% of supply, with rooftop solar providing strong daytime output and wind generation remaining variable throughout the month.
Several key factors influenced supply and prices in September:
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Muja Power Station (Collie): Scheduled maintenance reduced coal-fired generation capacity.
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Pinjar Power Station (Pinjar): Local network constraints added pressure during high-demand periods.
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Wind Generation: Fluctuations in wind output contributed to short-term price volatility.
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Rooftop Solar: Strong daytime output helped suppress prices during the day.
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Gas-Fired Generation: Increased reliance on gas-fired generation during low renewable output periods added cost pressures.
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Battery Storage: Battery storage assets, including the Collie Battery, helped stabilise the grid by storing excess renewable energy during high output periods and discharging during peak demand.
Futures Pricing
We observed that forward electricity prices for Western Australia in September 2025 showed moderate to high volatility:
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Base Month Futures: Fluctuated by roughly ±10–12%, tracking the average price trend.
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Evening Peak Prices: Spiked due to low wind generation, reduced rooftop solar contribution in the late afternoon, and high grid demand during peak periods.
what it means for your business
Energy costs in Western Australia remain sensitive to fluctuations in renewable output and high-demand periods. Midday rooftop solar provides some relief, but businesses face sharp price rises during evening peaks when wind generation drops or solar output declines. Maintenance outages at thermal plants, including Muja Power Station (Collie) and Pinjar Power Station (Pinjar), along with local network congestion, add further uncertainty, potentially impacting operational budgets, cash flow, and long-term energy planning.
If your business does not yet have a strategy in place, we can help. Contact us for a free bill check or to discuss a tailored energy procurement plan.
Western Australia is rapidly expanding its Battery Energy Storage System (BESS) capacity, with several major projects approved or under development to support the state’s transition to cleaner, more reliable, and dispatchable energy.
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Collie Battery Energy Storage System (BESS): On September 1, 2025, the WA government approved plans for a 200 MW battery energy storage system and up to a 66 MW solar farm to be constructed on farmland about 14 kilometres northeast of Collie. This project is being developed by Hesperia subsidiary Enpowered.
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Vanadium Battery Energy Storage System (VBESS) in Kalgoorlie: On September 9, 2025, the WA government committed $150 million toward the development of a locally manufactured VBESS in Kalgoorlie. The project aims to strengthen regional energy resilience, support long-duration storage solutions, and advance WA’s vanadium and battery manufacturing industries.
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Merredin Battery Energy Storage System (MEB): The MEB is a 100 MW/four-hour large-scale grid-connected energy storage project under development in Western Australia. The project, a joint development between Atmos Renewables and Nomad Energy, aims to support the state’s transition to cleaner energy sources by providing dispatchable capacity to the South West Interconnected System (SWIS).
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Capacity Investment Scheme (CIS) Projects: The federal government announced that four new big batteries—Boddington Giga Battery, Merredin Big Battery, Muchea Battery, and Waroona Renewable Energy Project—have successfully bid for support under WA’s first CIS tender. These projects are scheduled to be operational no later than October 2027 and will supply WA’s grid with an extra 654 MW of capacity, capable of discharging nearly 2,600 MWh of energy.
WHAT ARE THE IMPACTS
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Peak price moderation: By storing excess renewable energy during low-demand periods and releasing it during high-demand times, batteries help reduce sharp spikes in wholesale electricity prices.
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Smoothing price volatility: Dispatchable capacity from projects like Collie BESS, VBESS (Kalgoorlie), and Merredin BESS ensures more consistent supply, limiting extreme fluctuations caused by variable wind or solar output.
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Reduced reliance on gas and coal peakers: With more battery storage available, the grid can rely less on expensive gas or coal-fired plants during peak periods, lowering overall system costs.
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Support for long-term renewable supply: Increasing storage capacity allows more renewable energy to reach the market reliably, which can gradually reduce wholesale prices as the grid integrates higher proportions of low-cost renewable generation.
South West Interconnected System (SWIS) Transmission Plan
On 19 September 2025, Phase One of the SWIS Transmission Plan was officially released, marking a major step in expanding Western Australia’s renewable energy capacity. The plan aims to unlock a total of 2.6 GW of new generation, including 1 GW in the northern network and 1.6 GW in the eastern network. By connecting new wind and solar projects to the grid, the plan addresses transmission bottlenecks that have previously limited renewable energy development.
Key objectives of the plan include:
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Enabling renewable integration: Supports the connection of large-scale wind and solar farms, helping WA achieve its clean energy targets.
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Improving grid reliability: Strengthens the SWIS by upgrading transmission lines and reducing congestion, making the system more resilient to fluctuations in renewable output.
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Facilitating dispatchable energy: The plan creates capacity for energy storage solutions and other technologies to supply power during peak demand.
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Supporting regional development: Encourages investment in renewable projects across northern and eastern WA, creating jobs and economic opportunities in regional communities.
what are the impacts
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Moderating wholesale prices: Increased renewable capacity and improved transmission reduce reliance on expensive gas and coal peaker plants during peak demand periods.
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Reducing price volatility: Smoother integration of renewables helps prevent sharp price spikes caused by variable wind or solar output.
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Business planning certainty: Improved grid reliability and predictable energy supply assist businesses in budgeting and managing operational costs.
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Sustainability benefits: Greater access to renewable energy supports corporate ESG goals and decarbonisation strategies.
