Three energy firms will pay more than £10 million after a major power cut in the summer.

Large parts of the UK including Kent were struck with the "unprecedented power outages" on August 9, affecting nearly one million homes.

Traffic lights stopped working, a Medway shopping centre was evacuated but the biggest impact was on the rail network, where commuters faced huge delays.

The power cut lasted for 45 minutes.

Soon after the blackout, National Grid concluded it was caused by a lightning strike.

Following this announcement, government regulator Ofgem launched an investigation into the incident to establish whether the utilities company breached their licence conditions. It also looked into whether the right customers were disconnected.

Ofgem’s 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 loss of power and disruption to more than one million consumers.

It has concluded that two large power stations, Hornsea One Ltd (co-owned by Orsted) and Little Barford (operated by RWE) did not remain connected after the lightning strike.

Both companies will make a voluntary payment of £4.5 million.

Ofgem also found that although local network operators disconnected and reconnected consumers in response to the loss of power as expected, 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.

UK Power Networks has recognised this technical breach and agreed to pay £1.5 million into Ofgem’s voluntary redress fund.

Ofgem will now be conducting a review into the structure and management of the ESO and "has made further recommendations to ensure the UK continues to have one of the most reliable electricity systems in the world."

Executive director at Ofgem, Jonathan Brearley, said: "Consumers and businesses rely on generators and network companies to provide a secure and stable power supply.

"The power cut on August 9 showed how much disruption and distress is caused to consumers across the UK when this does not happen.

"That is why it is right that companies that were unable to keep generating have paid into our consumer redress fund.

"Our investigation has raised important questions about National Grid’s ESO, which is why our review will look at the structure and governance of the company.

"As the energy market changes it is vitally important we future-proof the networks to ensure consumers continue to benefit from one of the most reliable electricity systems in the world."

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