EirGrid has recently made 30-minute dispatch down data available for wind and solar in the Republic of Ireland (IE) and Northern Ireland (NI). I made a few charts based on these datasets which stretch back to 2021 and are currently updated through June 30, 2024. In June 2024, all-island dispatch down rate was 14.7% for wind and 7.6% for solar.
Looking at IE and NI individually, NI has consistently higher dispatch down rates than IE. Exhibit 1 shows monthly wind and solar generation, dispatch down levels, and dispatch down rates.
Exhibit 1: Monthly wind and solar generation dispatch down (DD) and DD rates, Republic of Ireland (IE) and Northern Ireland (NI), January-June 2024
These datasets are also more detailed than just curtailment and constraint, as the datasets also identify the amount of dispatch down by type within a 30-minute period:
- High Frequency/Minimum Generation (curtailment)
- Rate of Change of Frequency (RoCoF)/Inertia (curtailment)
- System Non-Synchronous Penetration (SNSP) Issue (curtailment)
- Transmission (TSO) Constraint (constraint)
- TSO Testing
Exhibits 2 and 3 show the shares of dispatch down by type for wind and solar respectively. Comparing the share of dispatch down by various causes between wind and solar and between IE and NI, there is a huge difference in why renewables are asked to reduce output.
- In Northern Ireland, the overwhelmingly common reason for both wind and solar dispatch down is transmission constraints.
- In the Republic of Ireland, solar is asked to reduce output mostly due to high frequency issues and minimum generation operational constraints. Wind is also mostly affected by high frequency/minimum generation, but transmission constraints also play a fairly significant role.
- The Republic of Ireland experiences more SNSP-related curtailment than Northern Ireland.
Exhibit 2: Share of wind dispatch down by type, Republic of Ireland (IE) and Northern Ireland (NI), January-June 2024
Exhibit 3: Share of solar dispatch down by type, Republic of Ireland (IE) and Northern Ireland (NI), January-June 2024
If you are interested in exploring these datasets yourself, they are publicly available here on Eirgrid's website under “DD Half-Hourly Data”.
Note: this dataset may be missing the latest solar farm in IE, Lysaghtstown Solar, which came online in February 2024. EirGrid’s press release on July 2 2024, states that utility-scale solar generation in the Republic of Ireland reached 110GWh in June 2024. However, solar generation in June totals only 95GWh based on data in dispatch down datasets. Green Collective's data shows Lysaghtstown generated 14.5GWh last month, which would bridge the gap in solar generation data from various EirGrid sources. Keep this in mind when you explore solar dispatch down data in the files.