AusNet and Hitachi Energy enable Victoria’s largest grid-scale battery connection
Features | 26.09.2025 | 3 min read
Australia is accelerating its path toward net-zero emissions by 2050, with more than 35 percent of its electricity already generated from renewable sources, such as wind and solar. To take the next step, the country is investing heavily in large-scale energy storage – critical in capturing clean energy when it’s abundant and delivering it reliably when demand peaks.
One of the most significant projects in this journey is the Mortlake Battery Energy Storage System (BESS), developed at AusNet’s Mortlake Power Station in Victoria. Once operational, the 300 megawatt capacity / 650 megawatt-hour facility will become one of the largest grid-scale batteries in the state, supporting grid stability and enabling greater integration of renewable energy, supplying equivalent power to around 135,000 houses.
We’re proud to deliver the critical 500 kV transmission infrastructure for the Mortlake BESS project: an initiative that strengthens Victoria’s energy resilience and supports Australia’s clean energy future. To realize this vision, we’ve partnered with Hitachi Energy, an industry leader with global expertise and local support. Their advanced transformer technology is essential to the success of this project, helping us deliver high-performance, future-ready infrastructure.
The Challenge: Connecting critical infrastructure on time, without compromise
As renewable generation in Australia expands rapidly, operators face increasing challenges in maintaining the stability and reliability of the electricity grid. Large-scale batteries offer a vital solution, but they require specialized infrastructure to operate at ultra-high voltage levels.
BESS provides multiple benefits: it enhances grid resilience by smoothing fluctuations from renewables, stores energy during periods of excess generation, and reduces reliance on fossil fuels while creating capacity for more clean energy projects to connect.
For AusNet, Victoria’s largest diversified energy networks business, the task was clear but challenging: to deliver the transmission connection for the Mortlake BESS. This meant securing two highly critical power transformers that could be designed, manufactured, delivered, and installed on a demanding project timeline. Reliability, safety, and quality could not be compromised – any delay would directly impact the ability to connect the BESS to the national grid.
Collaborating to deliver on a bold vision
To address the project’s scale and complexity, Hitachi Energy and AusNet collaborated closely from the outset. Together, the teams co-created the technical specifications and established a robust techno-commercial contractual arrangement. This ensured both supply chain resilience and the flexibility required to navigate evolving project needs.
Hitachi Energy delivered two state-of-the-art 500 kV (kilovolts), 180 MVA (megavolt-ampere) transformers, manufactured to the highest safety and quality standards. Engineered for cycling and dynamic loading, these transformers feature thermally upgraded insulation and advanced cooling technologies to deliver superior thermal performance. Their low-loss design helps reduce carbon dioxide emissions, making them environmentally friendly and ready for TXpert™ digital monitoring. Built to withstand solar radiation, harsh environments, and high short-circuit strength, the transformers ensure reliable performance for large-scale battery storage.
These transformers are central to the project, converting stored battery energy into high-voltage electricity and enabling its seamless transmission through the national grid.
This project reflects Hitachi Energy’s mission to advance a sustainable, flexible, and secure energy system. Our 500 kV transformers play a vital role in converting stored battery energy into high-voltage power. Once installed at Mortlake Terminal Station, they will enable efficient transmission into the national grid, connecting thousands of homes to clean, reliable energy.
A shared commitment to the future
AusNet and Hitachi Energy are not just powering homes; they’re powering Australia’s clean energy future. The Mortlake BESS connection is a landmark in the country’s clean energy journey, enabling deeper integration of renewables and reinforcing grid stability.
This milestone builds on the success of our 2024 collaboration on the Golden Plains Wind Farm – Australia’s largest onshore wind project. As part of the country’s strategy to achieve net-zero emissions, Hitachi Energy supplied two custom-built 850 MVA, 500 kV power transformers, manufactured using 100 percent fossil-free methods and delivered in record time. Together with AusNet, we enabled the grid connection that now powers over 765,000 homes with clean wind energy, reinforcing our shared commitment to a sustainable future.
It’s a model for how innovation, advanced technology, and partnership can accelerate the path to net-zero.
