Investigation into 9 August 2019 power outage

Aug 2019
Jun 2020

The Gas and Electricity Markets Authority (“the Authority”) opened an investigation into the power outage of Friday 9 August 2019, to establish the circumstances and causes of the outage and the lessons that can be learned to improve the resilience of Great Britain’s energy network, and to investigate the compliance of the key licensed parties involved with their licence and code obligations. A report on Ofgem’s findings can be found below.

The investigation found that the combined loss of two large generators, as well as the smaller loss of generation at a local level, together triggered the subsequent disconnection, loss of power and disruption to more than one million consumers. Two large power stations, Hornsea One Ltd (co-owned by Orsted) and Little Barford (operated by RWE) did not remain connected after a lightning strike. They have agreed to make a voluntary payment of £4.5 million each into Ofgem’s redress fund.

Local network operators disconnected and reconnected consumers in response to the loss of power as expected. However, UK Power Networks began reconnecting customers without being asked to by the Electricity System Operator (ESO), which could have potentially jeopardised recovery of the system. This has no impact on 9 August and UK Power Networks has recognised this technical breach, taken swift action to prevent any future reoccurrence, and agreed to pay £1.5 million into Ofgem’s voluntary redress fund. All parties have fully cooperated with the regulator throughout its investigation. 

In January Ofgem also closed its investigation into National Grid Electricity Transmission (NGET), and all five other DNO groups, namely Electricity North West Limited, Northern Powergrid, Scottish and Southern Energy, SP Energy Networks, and Western Power Distribution. We continued to review the ESO’s application of the security standards it is required to meet, alongside reviewing the standards themselves. Having explored this area, and noting that the standards themselves are to be amended, we have concluded that there is no merit in continuing the investigation. Therefore, we are closing this investigation on administrative priority grounds.

The incident has underlined the importance of the ESO adapting to the complex and changing world it operates in. Ofgem has already announced that it will be conducting a review into the structure and governance of the ESO, and the concerns raised in this investigation will inform this work. Ofgem has also made recommendations to ensure the UK continues to have one of the world’s most reliable electricity systems in the world, particularly as more small scale generation is connected to the system.

Alongside our report, the ESO’s reports submitted to Ofgem following the power cut on August 9 2019, can be found below.