For the second month in a row, battery discharge reached a record 396MW in Ireland’s transmission system in December 2025.
January 20, 2026
For the second month in a row, battery discharge reached a record 396MW  in Ireland’s transmission system in December 2025.
According to the latest data from state-owned transmission system operator (TSO) EirGrid, this record was set on Monday, 15 December, and exceeds last month’s record of 362MW, set on 25 November.
This latest record comes as Ireland opened its wholesale market to battery storage, under a new scheduling and dispatch programme, last November.
Overall, in December, renewables accounted for 43.8% of electricity generation on the Irish grid. Most of the renewable generation came from wind energy with 38.5%, up nearly four percentage points from the previous month, while solar accounted for 0.5%.
Even though the share of solar PV dropped during the winter season, 2025 was a record year for Irish home solar PV systems. According to data from the Sustainable Energy Authority of Ireland (SEAI), a record 34,0888 households installed solar panels last year, which represents a 16% increase from the previous year.
On Christmas Day, as peak demand shifted from evening to lunchtime – due to ovens and other appliances being switched on to prepare dinner –renewables provided 55% of the electricity demand during that day.
This was not the case for New Year’s Eve, as the celebrations took place late in the evening and night. For that reason, there was no shift in energy demand peak, which was more aligned with what is observed during most other evenings in the wintertime.
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Diarmaid Gillespie, Director of System Operations at EirGrid, said: “Similar to what we have seen in recent months, December was another strong month for renewable energy with us again seeing a significant amount of wind generation contributing to the overall fuel mix for the month.” 
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Section Editor, Jonathan Touriño Jacobo
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