The government expects solar and wind power to be cheaper than new nuclear power by the time Hinkley Point C is completed, its own projections show.



Theresa May’s government last month made a surprise decision to delay a deal on Hinkley, prompting a renewed look at what alternatives could power Britain if ministers this autumn fail to back new reactors in Somerset.



An unpublished report by the energy department shows that it expects onshore wind power and large-scale solar to cost around £50-75 per megawatt hour of power generated in 2025. New nuclear is anticipated to be around £85-125/MWh, in line with the guaranteed price of £92.50/MWh that the government has offered Hinkley’s developer, EDF.



On previous forecasts, made in 2010 and 2013, the two renewable technologies were expected to be more expensive than nuclear or around the same cost. This is the first time the government has shown it expects them to be a cheaper option.



The figures were revealed in a National Audit Office (NAO) report on nuclear in July. “The [energy] department’s forecasts for the levelised cost of electricity of wind and solar in 2025 have decreased since 2010. The cost forecast for gas has not changed, while for nuclear it has increased,” the NAO said.



The NAO cited the forecasts as coming from the energy department in March 2016. The department said the NAO had been provided with an early draft of its report, and the full version would be published soon.



Niall Stuart, chief executive of the trade body Scottish Renewables, said: “These numbers speak for themselves: onshore wind and solar will be significantly better value than all other large scale sources of power in the UK by 2025.

“It is time to start backing the two technologies to deliver the clean power we need to hit our climate change targets and the cheap electricity required to keep bills down for consumers.”

Molly Scott Cato, a Green party MEP, said: “These latest figures confirm what many of us have been saying for years: that the Hinkley project is a dud.

“The cost of renewables is tumbling and Hinkley will become a giant white elephant as it struggles to compete with cheaper renewable options. Research has shown that solar power would be a less costly way of generating the equivalent amount of power, and now the government’s own projections show that onshore wind too will be cheaper than nuclear by the time Hinkley is built.”

Since coming to power in May 2015, the government ended onshore wind subsidies and allowed communities to veto turbines near them, as well as axing and cutting various subsidies for solar.



Government data published on Thursday showed that renewables generated 25.1% of the UK’s electricity in the first quarter of this year. Around half of that came from on and offshore wind combined.



At the weekend, high winds in Scotland helped windfarms match the entire country’s electricity needs for a day. Scotland has some of the biggest onshore windfarms in the UK, and a target of generating 100% of electricity from renewables by 2020.