GC0183: Generator and Interconnector Availability During a Severe Space Weather Event
What is being proposed
This modification will make changes to the Grid Code to obligate Generators and Interconnectors to notify NESO of their intended position in the event of severe space weather.
Current status
The Proposal was presented to a Special Panel in July 2025, where the Panel recommended Urgency, which was agreed by Ofgem. Workgroup Nominations ran from 17 July to 29 August. The Workgroup Consultation ran from 19 August to 29 August and received 6 responses. The Workgroup Report was been submitted to the Panel for a Special Panel meeting on 18 September, where the Panel agreed the Terms of Reference had been met and agreed for the modification to proceed to Code Administrator Consultation.The Code Administrator Consultation closed on 20 October. The Draft Final Modification Report will be submitted to the Panel on 27 October. 02/12/2025: The Authority approved the Original solution on 20 November. This will be implemented on 04 December.
Details
Timeline
Analysis
NESO introduces Grid Code modification GC0183 requiring generators and interconnectors to notify their intended availability during severe space weather events. Ofgem approved the modification on 20 November 2025 with implementation on 4 December. The modification proceeded through urgent procedures due to national security implications.
Why it matters
This creates a new operational obligation on generators and interconnectors to declare availability under extreme conditions, shifting from voluntary coordination to mandatory disclosure. The urgent procedure bypassed normal consultation periods, suggesting government concern about grid resilience during geomagnetic storms that could damage transformer equipment.
Key facts
- •Implementation date: 4 December 2025
- •Approved under urgent modification procedures
- •Workgroup consultation received 6 responses in 10-day period
- •High impact on generators, interconnectors, and NESO