Ofgem inquiry into electricity system operation during extreme heat in June 2026
- Publication type:
- Transparency document
- Publication date:
- Topic:
- National Energy System Operator (NESO)
An update on our areas of focus and NESO's preliminary report on system stress during extreme heat in the week of 22 June.
Details
During the summer of 2026, Great Britain and Europe experienced periods of extreme heat. National Energy System Operator (NESO), the body responsible for operating the electricity system, took a range of actions to manage operational challenges for the electricity system in Great Britain (England, Scotland and Wales).
Ofgem is inquiring into the events of the June 2026 heatwave. Our aim is to provide transparency about what happened and determine whether any improvements to system arrangements are needed to ensure the system remains resilient to similar events in the future.
In July, we formally commissioned a team within NESO to review the events of the week. The NESO review team provided a factual preliminary report on 11 September. We are publishing that report as well as an update on Ofgem's main areas of focus.
Ofgem's focus areas include:
- system security
- NESO's planning, forecasting and operational decision-making
- interconnector flows
- generator availability
- the response of balancing services and the electricity market
The NESO review team will share its final report with Ofgem in December. Once we have received and considered that report, we will form an independent Ofgem view and publish conclusions. This will include conclusions on whether the system remained secure, whether the requirements governing system operation were followed, and whether lessons can be learned to strengthen system security for the future.
Note: Some of the files attached below might not be fully accessible. If you require an alternative format, please contact nesoregulation@ofgem.gov.uk.