Updated February 9, 2026 – Western Australia’s largest state-owned battery, the 500 MW/2,400 MWh Collie battery energy storage system (CBESS), has officially began operations in Collie. Operated by state-owned utility Synergy, CBESS sits opposite the aging Collie Power Station. It is capable of powering the equivalent of about 785,000 homes for over four hours, making it one of the largest operational grid-scale batteries in Australia. Synergy’s Collie battery storage system captures excess wind and solar generation for redistribution to the South West Interconnected System (SWIS) during peak demand or low renewable output periods. This is expected to support grid reliability as Western Australia moves toward retirement of state-owned coal generation by 2030.
Synergy’s Collie battery energy storage system (CBESS) project is part of broader Western Australia decarbonization goals. It also features in the Just Transition strategy with more than AU$1.6 billion in investment. The project has also been able to support local jobs during the EPC phase. In prospective expectation, Collie BESS is also expected to complement other grid-scale batteries already operational or under development in the state and the country, like the Templers BESS in South Australia.
Key Contractors, Partners and Suppliers Involved in the Collie Battery Project
Collie battery energy storage system project attracted the interest of major companies and organizations throughout its construction, equipment supply, and system delivery phases. These include:
- Synergy, a state-owned energy company – Owner, operator and principal delivery agency for the CBESS project.
- SCEE Electrical – Local electrical contractor leading portions of the physical battery installation and electrical fit-out during construction.
- Power Electronics – Supplier of key inverter technology. The company was contracted to deliver 160 inverters for the Collie battery.
- Contemporary Amperex Technology Co. Limited (CATL) – Major battery cell supplier. CBESS uses 640 CATL EnerC Plus 4.07 MWh lithium-ion battery units.
- ABB eHouse Solutions – Provided modular electrical houses and system integration components including switchgear, protections, and controls as part of the battery plant infrastructure.
- WA Government, Cook Labor Government – Principal financier and policy sponsor, with multiple departments overseeing approvals, transition planning and community engagement.
How the Project Unfolded: Key Milestones and Overview of Project Timeline
March 2024: Site surface works and earthworks commenced. Local contractor engagement also announced.
April 2025: Battery container installation completed – featuring 640 units. Key electrical components such as inverters and medium-voltage systems are also installed at the Collie site.
2025: Commissioning phases progressed through system testing. Integration with the SWIS, and operational readiness verification also done.
February 2026: Official operational status reached.
Synergy’s Collie BESS: The Largest Battery Storage Under Construction in Australia
Reported October 31, 2025 – The Collie Battery Energy Storage System (CBESS) is a large-scale energy storage facility developed by Synergy, located adjacent to the Collie Power Station in Western Australia. The project, now complete, marks a major milestone in the state’s transition from coal-fired power to renewable energy.
With an installed capacity of 500 megawatts (MW) and 2,000 megawatt hours (MWh) of energy storage, the CBESS is designed to store excess renewable energy generated during the day and discharge it into the South West Interconnected System (SWIS) during periods of high demand.
The facility comprises 640 battery units and 160 inverters, making it one of the most powerful battery systems in Australia. According to Marlon Cooray, Synergy’s Manager of Major Projects, “This is Synergy’s third large-scale battery project and the most ambitious yet. The CBESS project can store 10 times the energy of KBESS 1, which Synergy deployed just two years ago.”
SWIS is also getting support from Neoen’s 341 MW/1,363 MWh Collie Battery Stage 2, that reached a delivery milestone on October 1, 2025. Neoen has also launched construction of the 164 MW/905 MWh Muchea Battery project. The is the country’s first six-hour grid-scale battery. Australia has several BESS projects in development such as the the Belah Battery Energy Storage System (BESS) in Queensland, Australia being developed by Eku Energy, in partnership with LP Renewables.
Synergy’s Collie Battery Energy Storage System (CBESS) Factsheet
Location: Adjacent to Collie Power Station, Western Australia
Developer: Synergy
Capacity: 500 MW/2,000 MWh (4-hour duration)
Technology Use: 640 battery units and 160 inverters
Synergy’s CBESS Project Timeline
Pre-2023: Planning, feasibility, environmental studies conducted
June 2023: Early civil works starts
July 2024: GHD starts construction
October 2024: Battery installation starts. 640 units and 160 inverters also ordered and delivered
April 2025: All battery units and inverters installed on site at Synergy’s Collie BESS
Late 2025: Expected commissioning date
Construction of Collie BESS, the Largest Battery Storage in Australia, Begins
Reported March 20, 2024 – Synergy, Western Australia’s largest energy retailer and generator with more than one million industrial, commercial and residential customers, has announced the start of construction of Collie BESS, the largest battery energy storage system in the country.
The start of construction comes approximately 3 months since the project was approved for construction next to the 300 megawatts Collie coal-powered power plant in Collie, South Western region of Western Australia in December 2023.
The 500MW/2000MWh capacity system with the potential to be expanded to 1 GW/4 GWh in the future is the latest project from Synergy. Additionally, the company plans to build a total of 3GWh of energy storage systems in the country by 2025. In May 2023, Synergy also delivered Kwinana Battery Stage One which is currently providing power to the South West Interconnected System.
Kwinana Battery Stage Two is another one of its BESS projects. Kwinana 2 scheduled completion date is November 2024. Collie BESS on the other hand is set for delivery in late 2025 at a cost of roughly $1 billion.
Upon completion, Australia’s largest battery storage system will utilize modularized batteries with a life expectancy of 20 years. It will mop up excess energy from rooftop solar projects and discharge the power in the evening when electricity demand is usually high.
Noteworthy, the four-hour capacity facility will meet approximately 64% of the state’s new energy storage capacity announced back in June 2022.
Collie BESS Project Team
Collie battery energy storage system is developed by Synergy, a corporation owned by the Government of Western Australia. The state government is funding the project as part of the state’s accelerated transition to renewables. This transition is driven by the huge opportunities on the table from switch to green energy – for industry, mines and consumers – and by the urgent need to replace ageing coal generators.
Other companies behind the development of the largest battery energy storage system in Australia are Cardinal Contractors, Contemporary Amperex Technology Co Ltd (CATL) and Power Electronics. Cardinal Contractors is an earthmoving and heavy haulage company headquartered in Collie, Western Australia. The company was recently awarded the contract to complete site preparation earthworks for the Collie BESS project.
CATL on the other hand is a Chinese battery manufacturer and technology company that specializes in the manufacturing of EV lithium-ion batteries. It also manufactures energy storage systems as well as battery management systems (BMS). In 2023, the company was awarded a contract to supply 650 EnerC Plus containerized liquid-cooling battery systems for the Collie BESS project.
In the same year, Synergy also contracted Power Electronics to supply 160 inverters for the project. Headquartered in the USA, Power Electronics is the world’s leading battery energy storage system provider. It is also the first manufacturer of solar inverters for utility-scale photovoltaic plants in America, Oceania and Europe.
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