Large battery storage units are now playing a bigger role on Ireland’s electricity system, after a large change introduced by EirGrid and its partners last year.
Before November 2025, grid-scale batteries mainly supported stability on the power system. These units are now able to trade energy more actively, charging when renewable energy is abundant or prices are low, and discharging to supply power when demand is high. This can help reduce reliance on conventional fossil-fuel generation.
“The battery units, known technically as energy storage power stations, are now fully integrated into the real-time electricity market helping to manage supply and demand more efficiently,” said Liam Ryan, chief transformation, technology and offshore officer at EirGrid. “As a result of the change, just three months on, we are already seeing reliance on conventional generation reducing by almost 400MW on some days when demand is very high.”
EirGrid has also observed a number of records for battery discharge on the electricity system in Ireland, reaching 502MW on December 15th, 2025.
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“We saw that system flexibility has improved to the point where a generator-sized block of capacity could be taken offline during a winter evening peak in December,” said Ryan.
EirGrid is responsible for operating, developing and enhancing Ireland’s electricity grid and market operations, while also planning for Ireland’s long-term electricity needs.
“Operating a power system with electricity generated from high levels of variable renewables, such as wind and solar, is complex and technically very challenging.
“There’s a need to collaborate in partnership with technology owners to overcome the limitations of many established technological and operational practices, while making sure the grid remains stable and secure and energy storage can play a significant role in that regard.”
The first battery was installed on the power system in Limerick in 2019, and today more than 1GW of installed capacity and 1,100 MWh of storage are available from a mix of 30-minute, 1-hour, 2-hour and 4-hour batteries. This equivalent to two large gas generators running at full output for an hour.
Minister for Climate, Energy and the Environment Darragh O’Brien welcomed the progress being made.
“The role of battery storage in Ireland’s energy needs is critical, so it’s positive to see the impact this update is already having on the power system since being introduced last November,” the Minister said. “As we move away from fossil fuels to integrating more wind and solar power, battery technology will become increasingly important.”
“We’ve seen the number of battery units operating in Ireland has increased over recent years, with more continuing to connect to the power system,” he said.
Following extensive engagement with industry and stakeholders, the update was introduced by EirGrid, SONI (it’s counterpart in Northern Ireland) and SEMO (the Integrated Single Electricity Market).
“Since the change was introduced late last year,” said Ryan, “we’ve seen up to 60 per cent more energy being delivered and consumed by these batteries in the first 70 days post introduction, with an increase in trading on the day-ahead electricity market, pointing to strong adoption of the new approach.
“Looking forward, we expect a shift towards more ex-ante (day ahead) trading for batteries, and the continued positive evolution in the use of storage on the system, which is critical due to the variable nature of wind and solar power.
“This milestone shows how storage is no longer just a supporting technology, but it is a core part of system security and flexibility.”
