Construction Begins on Aussie DC-Coupled Solar and Battery Hybrid System
Wärtsilä and Octopus Australia have broken ground on one of Australia’s first large-scale direct current (DC)-coupled solar and battery hybrid systems.
The 64 MW/128 MWh battery storage system will be co-located at Octopus’s 80-MW Fulham Solar Farm in Victoria. Octopus Australia is a renewable energy manager with more than $11 billion in wind, solar, and battery storage assets in Australia. It is part of Octopus Group, a UK-based investment and energy company.
Wärtsilä will provide the DC-coupled battery system as well as the power plant controller technology.
“The system will enhance renewable energy efficiency, supporting the state of Victoria’s ambitious target to achieve net zero emissions by 2045,” said David Hebert, Director of Sales Management, Wärtsilä Energy Storage. “The Fulham Battery represents a significant step forward in integrating advanced energy storage solutions into the Australian grid.”
DC-coupled systems are more efficient The co-located project highlights the trend of integrating renewable energy and storage to support grid stability. It also aims to demonstrate the value of DC-coupled technology at scale.
There are two types of electrical currents—direct current (DC), which flows in a single direction, and alternating current (AC), which switches directions 50 times per second in Australia (and 60 times per second in the U.S.).
While AC has been the grid standard for more than a century, DC’s stock has risen in recent years, thanks in part to the growing adoption of DC-based renewable energy technologies. With an AC-coupled system, the DC energy generated by solar panels is converted to AC by an inverter.
Any excess solar that’s generated is routed to a battery inverter where it’s converted back to DC for storage. When the batteries are discharged, the power is converted back to AC. This DC-to-AC-to-DC-to-AC conversion introduces energy losses and adds complexity, cost and latency.
DC coupling, on the other hand, enables solar energy to be delivered directly to the battery for storage, minimizing conversion losses when integrating energy storage with solar assets. Proponents say the technology is more efficient, less expensive, and can better support the grid.
The Fulham Solar Farm and Battery project, which is valued at over $300 million, was funded with equity capital contributions from the Clean Energy Finance Corporation, Westpac Private Bank and others. Octopus has also secured a power purchase agreement from the Victorian State Government.
The company is working on similar solar and battery projects in New South Wales and Queensland.
The “Fulham Solar Farm and Battery marks a major step forward in our mission to accelerate Australia’s energy transition,” said Sonia Teitel, co-managing director of renewables for Octopus Australia. “This project demonstrates our ability to bring together institutional capital, government support, and leading-edge technology to create renewable assets that provide long-term benefits to our communities and investors.”
Project to be complete in 2027 The Wärtsilä intelligent power plant control software, known as GEMS, will coordinate between the solar farm, storage system and the grid, optimizing energy management operations and ensuring the hybrid plant meets grid requirements and response times.
The company will also ensure the project’s ongoing performance and reliability through a long-term service agreement.
“We chose to partner with Wärtsilä due to their strong track record as a global integrator, their innovative approach, and their proven ability to support complex projects. We are excited to work together on one of the first DC-coupled large-scale energy storage systems in Australia,” said Sonia Teitel, Co-Managing Director of Renewables at Octopus Australia.
The solar farm and battery storage systems are expected to be fully operational in 2027.
