Bosses at Hinkley Point C have pushed back the start of electricity generation by six months to June 2026.
EDF said “significant progress” had been made at the site near Bridgwater, despite the impact of the pandemic.
The cost of the nuclear power project is now estimated to cost between £22bn and £23bn, around £500million more than previous estimates of £21.5bn – £22.2bn.
The Managing Director of Hinkley Point C Stuart Crooks says: "None of this extra cost is carried by British consumers".
He goes on to say: "At the start of the crisis we postponed some of our work in order to create space and keep people safe while on site.
"The aim was to bring in additional resources to catch up that lost time but ten months on it's clear that the pandemic is still in full force."
"So far, we estimate we've lost around three months of scheduled time and we estimate we could lose up to another three months in 2021, assuming the conditions allow us to ramp back up resources following Easter."
The energy firm says their ambition to to lift the first dome on Unit One by the end of 2022 remains unchanged
Talking about the delays, Stuart Crooks says: "This means we have not been able to bring on the extra people needed to catch up on work we postponed at the height of the crisis. Even though experience has allowed us to increase numbers on site during the pandemic from below 2,000 to more than 5,000, social distancing requirements still limit the number of people we can safely have on site at any one time."
HINKLEY POINT C TIMELINE
David Cameron visited the site and announced the new plant would bring thousands of jobs to the whole of the South West and supply seven per cent of the nation's energy needs.
During the last year however the project has been beset with problems. The French firm EDF put off a decision on at least three occasions before finally approving it in July.
Government announced they have decided to proceed with the first new nuclear power station for a generation
First concrete successfully poured for power station
The Christmas families in the UK were promised they would be cooking their turkeys with power from EDF’s new nuclear plant at Hinkley Point C.
EDF said Hinkley C will come online by the end of 2025.