In this release, Electricity Supply refers to the supply of electricity from grid-scale operators, primarily main activity producers, whose main activity is the supply of electricity for sale to other parties. It does not include all generation by autoproducers, who generate electricity mainly for their own use such as generation from rooftop solar panels, small scale wind-turbine generation, or Combined Heat and Power (CHP) units at manufacturing plants.
The supply is broken down by source: trade flows, electricity generation energy source, and storage outputs. The data for 2025 are available at yearly, monthly, daily and hourly periodicity. The supply total is calculated as the sum of generated electricity, net imports and storage output.
Electricity supply is not equal to consumer demand due to transmission and distribution losses. This needs to be taken into account if comparing supply data with metered consumption data.
Net imports of electricity are calculated as the sum of imports minus exports.
The units for electricity used in this release are Megawatt Hours (MWh) and Gigawatt Hours (GWh), where 1 GWh = 1,000 MWh.
The CSO received the administrative microdata from EirGrid who are the Transmission System Operator (TSO) for electricity in Ireland. The data were requested under the Statistics Act, 1993.
Eirgrid publish data on electricity supply by aggregate energy sources on their website. This release and the corresponding PxStat tables provide additional information by breaking down the electricity supply by all energy sources on an hourly basis.
Several different data files are processed. The Single Electricity Market (SEM) files contain the metered data from the largest generators. Data are also provided from the Distribution Operator (DSO), which typically covers the metered data from smaller generation plants. Separate files were received with imports and exports of electricity from Northern Ireland and Great Britain.
The electricity unit in the SEM file is recorded in Megawatt Hours (MWh). The electricity in the DSO data was in kilowatts (kW) which was converted to MWh.
| Generation Sources |
Gas Oil Coal Distillate Other Non-Renewable Hydrogenated Vegetable Oil (HVO) Biomass/Peat Waste Wind Solar Renewable Hydro Other Renewable |
|---|---|
| Storage Sources |
Battery Storage Pump Storage Hydro |
| Supply Sources |
Renewable Generation Non-Renewable Generation Storage Net Imports |
Storage sources such as batteries and pump storage hydro are treated separately from generation sources as they cannot be treated as renewable or non–renewable sources of electricity. These sources store electricity that is either generated or imported onto the grid, and therefore the renewability of these sources depends on the original source of the electricity. However, these storage systems can be used to store electricity during times of high renewable generation, and used to meet peak time demand, reducing the need for non-renewable generation during these high demand times.
In this release the generation data is aggregated by primary generator fuel and allocated as a renewable or non-renewable source on that basis. This is not the same methodology as used for the renewable energy share in electricity (RES-E) figures published by Eurostat, and therefore the figures differ. See Eurostat’s RES-E data and methodology.
Some energy sources, for example Biomass/Peat and Waste, are comprised of a mix of renewables and non-renewables. However, because there has been no electricity generation from peat since 2023, this Biomass/Peat category is classified as renewable in the 2025 data. For categories that still contain a mix of renewables and non-renewables, National Energy Balance published by the Sustainable Energy Authority of Ireland (SEAI) is used to determine the percentage split between renewables and non-renewable, and the dominating one is used to classify the category.
For 2025 the following generation sources are considered renewable: Hydrogenated Vegetable Oil, Wind, Solar, Waste, Biomass, Renewable Hydro, and Other Renewable.
System non-synchronous penetration (SNSP) measures the real-time share of electricity coming from non-synchronous sources, such as solar and wind. On the all-island Irish grid managed by EirGrid, the current operational limit is 75%. The share of renewable electricity generation reported in this release is not the same as the SNSP percentage as it includes all renewable sources, not just non-synchronous ones, and it refers to Ireland’s electricity generation, rather than all-island supply.
The data are subject to revision on an ongoing basis. EirGrid monthly Outage Reports show metered electricity generation and supply by source for each month. At the time of publication, the data in this release for 2025 matched the Outage Report.
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