Irish Grid Monthly: September 2026
TL;DR
- The percentages of the island's electricity demand met by each source during September 2026:
- 43.0% renewables (36.8% wind, 4.8% solar, 0.3% hydro, 1.1% biomass)
- 39.1% fossil fuels (37.5% gas, <0.1% oil, 1.6% waste-to-energy)
- 1.3% storage (0.8% pumped storage, 0.5% batteries)
- 16.5% net imports
- Windiest September yet with 25% of dispatch down: 1256GWh from wind farms was equivalent to 36.8% of electricity demand. Both figures are the highest ever for a September month. Meanwhile, 10% of wind dispatch down was due to curtailment and 15% due to constraints. In addition to county-level breakdown, we also look into which transmission nodes saw most constraints in the deep dives section on wind below.
- New battery discharge record of 482MW on September 28: Two main factors made the new records possible: high prices in both Ireland and GB that day, along with a 100% match between physical notifications and actual dispatch during peak hours. Details in the deep dives section on storage below.
- Solar generation is unsurprisingly down in September compared to August, though September 2026 still saw ~50% increase from September 2025. The following map shows locations of solar farms, typical peak output, and the first year they generated a significant amount of electricity.
Emissions
In September 2026 the Irish grid emitted approximately 567,000 tonnes of CO₂ ranging for an average grid carbon intensity of 198gCO₂/KWh with highs and lows of 396gCO₂/KWh and 100gCO₂/KWh, respectively.
That's both the lowest volume of CO₂ and lowest average grid carbon intensity yet for a September month, narrowly beating September 2025's 577,000t and 213gCO₂/KWh. Also, we're happy to report that for the first nine months of 2026, seven have seen the lowest ever emissions for that month of the year – the only exceptions so far are February and August.
County-level analysis
The top five renewable-producing counties in September 2026:
- Offaly
- Kerry
- Cork
- Galway
- Mayo
As the sun declines, the large wind producing counties dominate the charts once more: Meath leaves us, presumably until next summer, while Offaly, Cork, and Kerry jostle for the top three positions.
Offaly claims #1 spot this month but only just: its Edenderry biomass plant ran at partial output for much of the month and both Offaly and Kerry totalled roughly 130GWh; had Drombeg Solar Farm been producing (it's now been offline for three months), Kerry almost certainly would have taken top spot.
Deep dives (wind, solar, storage, fossil fuels, etc)
Thank you for reading! The rest of the newsletter is available to paying subscribers only. We go into more details on our dispatch down estimates and point you to specific transmission nodes that saw most constraints in September. We also look at how the latest battery discharge record was achieved. You can upgrade to a paid subscription to access all our analysis.