French independent power producer Neoen, now completely owned by Canadian asset manager Brookfield, has switched on the second phase of its 560MW/2,240MWh Collie Battery Energy Storage System (BESS) in Western Australia. The BESS has already begun discharging energy to the Wholesale Electricity Market (WEM) in Western Australia.

Project Development and Timeline

Stage 1 of the Collie BESS, sized at 219MW/877 MWh, began operating in October 2024, less than 18 months after construction commenced. The first phase features 224 Tesla Megapack 2XL units and represents Neoen's first major project in Western Australia. The BESS is located in proximity to Synergy's 2GWh Collie Battery Energy Storage System.

Building on the success of Stage 1, Neoen has now completed the second stage of the Collie Battery, adding 341 MW/1,363 MWh through the installation of 348 Tesla Megapack 2XL units. The combined project totals 560 MW and 2,240 MWh of energy storage capacity.

Grid Services and Contracts

On October 1, the BESS began delivering its contracted 197MW/4-hour grid capacity service to the Australian Energy Market Operator (AEMO). This service, known as 'Non-Co-optimised Essential System Services' (NCESS), is contracted for a two-year period. The BESS charges during daylight hours when solar generation is abundant and discharges during evening peak demand periods.

In April 2024, Neoen secured a similar 300MW/4-hour NCESS contract with AEMO for Stage 2. This contract will run for two years, commencing on October 1, 2025, and provide 300MW for a duration of four hours.

Regional Energy Storage Growth

The South West Interconnected System (SWIS), which covers much of southwestern Western Australia, including the state capital Perth, is currently on track to reach over 1.6 GW/6 GWh of operational BESS capacity by the end of 2025. This capacity is expected to double to over 3 GW/11 GWh by the end of 2029. Dom Watson, renewables development lead for future energy at state-owned company Synergy, confirmed that Synergy's 2,000MWh Collie BESS in Western Australia is on track to be online “by the end of the year.”

Speaking at the Battery Asset Management Summit Australia 2025, Watson noted that the Collie BESS, currently undergoing its commissioning phase, is expected to be delivered by the end of the year.

Synergy's Battery Development Program

The installation of all 640 battery packs and inverters for Synergy's Collie BESS commenced in early October 2024 and was completed in April 2025. Construction on the site, which is set to be one of Australia's most significant battery projects, started in March 2024. The facility is located at the site of the 300MW Collie Power Station, a coal-fired power plant scheduled for decommissioning in 2027. The Collie BESS will be connected to the SWIS.

Synergy has several large-scale BESS projects that are operational and under construction. Last year, the organization completed its 200MW/800MWh Kwinana 2 BESS. Construction began in July 2023, and the project was completed before Christmas 2024. Kwinana 2 is situated adjacent to the first Kwinana BESS 1, a 100MW/200MWh 2-hour duration system, at the existing gas-fired Kwinana Power Station.

Supply Chain Challenges and Solutions

Watson outlined significant supply chain challenges encountered during the development of large-scale battery storage projects. “What we found ourselves was not only a huge task in delivering pretty material development projects in their own right, but we were also doing that right in the middle of some supply chain issues,” Watson noted.

There were supply chain concerns for batteries, inverters, and transformers. Initially, Synergy thought batteries would be the equipment that needed to be secured earliest. However, Watson explained that “we soon found out that the power conversion systems (PCS) were probably the critical bit of equipment that needed to be secured as quickly as we could.”

As a result, Synergy abandoned the traditional engineering, procurement, and construction (EPC) model, finding it too rigid and slow for managing supply chain risks across its large project portfolio. Instead, it adopted an “integrator model” that directly managed procurement, design, and construction as separate packages, giving it greater flexibility and control over supply chain challenges during project delivery.

Watson continued: “We selected the integrated model, which was great as a concept for delivering these projects at pace. But we realised we weren't structured to deliver projects like this, and we'd never done it before at Synergy. However, we knew we needed to scale quickly, and we knew we needed to keep delivering at pace with control.”

Synergy formed an “integrated project management team” by partnering with engineering firm GHD, which provided engineering expertise to complete detailed integration designs and develop IFC (Issued for Construction) packages. GHD also supplemented the company's project management capabilities by hiring additional project managers and implementing control systems.

This partnership enabled real-time decision-making without commercial constraints, which proved essential for delivering large-scale, complex projects amid the challenges of the supply chain. Watson provided a deep dive into Synergy's operations in Western Australia, highlighting how the company has transitioned from relying on coal-fired power stations to renewables and energy storage during his presentation at the Battery Asset Management Summit Australia 2025.

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