The world’s largest operating offshore wind farm – the Orsted-run Hornsea 1 – will pay £4.5m ($5.9m) over its part in a massive blackout that left more than a million people without power last summer.

The 1.2GW Hornsea 1 off eastern England will pay out after dropping off the network as part of a wider sequence of failures that hit the UK system in August.

Along with a simultaneous disconnection by a gas-fired plant – whose operator RWE will pay the same sum – the event, triggered by a lightning strike on a transmission line, caused chaos to transport and other critical infrastructure.

UK energy regulator Ofgem, which launched a probe into the blackout, said: “Consumers and businesses rely on generators and network companies to provide a secure and stable power supply. 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.”

The Danish offshore wind giant said in a statement sent to Recharge: “Together with every organisation involved with the UK electricity system, we work hard to provide a reliable, resilient service and take any interruption very seriously. The power outage on August 9 was caused by an extremely rare sequence of events, involving a number of parties, and the issue we experienced at Hornsea 1 was quickly resolved.

“However, in recognition of our role in the outage, we have offered to make a voluntary contribution to Ofgem’s redress fund. We have co-operated with Ofgem throughout their investigations and conducted a thorough internal review of the events in order to prevent a situation like this from happening again.

“We will continue to work hard to bring clean, carbon free electricity to millions of homes across the UK.”

Hornsea 1 was at the time of the blackout still under construction and only partly exporting power from its 7MW Siemens Gamesa turbines, the last of which was installed in October.