We depart from our usual quarterly market review to provide an annual retrospective of Western Australia’s Wholesale Electricity Market (WEM) in 2025.
Download the full report (PDF, 2.3 MB)
Some of our main observations from 2025:
- Peak operational demand and renewable penetration records were broken.
- The minimum operational demand was not broken for the first time since 2017, a direct result of >400 MW of large battery charging in the middle of the day propping up operational demand.
- Essential System Services (ESS) costs are normalising back to pre-reform levels, after two years of abnormally high ESS costs post WEM Reform (from 1 October 2023).
- Peak Reserve Capacity margins remains tight looking out to the 2027-28 Capacity Year, while the total value of the Reserve Capacity Mechanism has increased significantly since the trough in the 2021-22 Capacity Year.
- Transmission loss factors for generation have generally improved across the SWIS.
- The coal generation fleet was required to flex less in 2025 than in previous years, while the gas generation fleet faced increased pressure.
- Four new facilities were commissioned in 2025: Cunderdin Solar PV/BESS, Kwinana Waste-to-Energy, Neoen Collie Battery Stage 2 and Synergy Collie BESS.
- Batteries are participating in the market in different ways, from pure energy arbitrage, provision of ESS only and a combination of both.