A group of 14 renewable energy companies have written a joint letter to business and energy secretary Greg Clark urging him to allow onshore wind to compete in future Contracts for Difference auctions.

The signatories include the renewable developers Scottish Power Renewables, SSE, Innogy, Statkraft and Vattenfall, as well as the turbine suppliers Siemens Gamesa and Vestas.

The letter states that onshore wind is not only the “cheapest form of new power generation” but also enjoys strong public backing, with more than three quarters of respondents expressing their support for the technology in the government’s own opinion polls.

It says new onshore windfarms could be built at a “subsidy-free price” but investors need the financial certainty provided by a guaranteed price for electricity.

The letter claims that resuming auctions for more established pot 1 technologies between 2019 and 2025 would provide a £1.6 billion “payback” for consumers through lower energy bills.

Mature technologies have been unable to bid for the contracts since the first auction round in 2014/15. The second auction round in 2017 was reserved for less established pot 2 technologies and was dominated by offshore wind.

In its 2015 general election manifesto, the Conservative party pledged to “halt the spread of subsidised onshore windfarms” in response to local opposition.

Following the vote, the government reformed planning regulations to put “power in the hands of local people”. Under these new rules, onshore wind projects can only be built in areas deemed suitable by local authorities and only with their backing.

The Conservative party maintained its opposition to “more large-scale onshore wind power” in England in its 2017 manifesto, implicitly opening the door to new projects in other nations of the UK. The party also explicitly stated its support for onshore wind on remote islands in Scotland.

The government announced in October 2017 that £557 million of annual subsidies would be made available through future auctions for immature technologies. In June of this year, it confirmed that onshore wind projects on remote Scottish islands would be able enter these auctions, and in July announced that the first would open by May 2019, with more following on a regular basis once every two years.

However, there is still no indication as to when mature technologies will again be allowed to compete in the auctions. In an interview for The House magazine in March, energy and clean growth minister Claire Perry disputed the description of the government’s position as a “ban”, saying there will be more auctions for onshore wind and solar. “We just haven’t yet said when,” she explained.

The letter to Clark argues: “The government has delivered on its manifesto commitments, through changes to planning legislation and the National Planning Policy Framework. Therefore, we call on the government to enable onshore wind to be developed in those communities that want to reap the benefits in social as well as economic terms.

“Facilitating the development of onshore wind is pragmatic and perfectly in line with manifesto commitments, and the view publicly expressed by Scottish Conservatives that there should be support for onshore wind where it is appropriate and local communities support it.”

Renewable UK executive director Emma Pinchbeck said: ”We trust the secretary of state will take account of the views of these major UK employers who are offering to build subsidy-free projects as part of the clean energy system of the future.

“His department’s opinion polls consistently highlight the overwhelming level of public support for onshore wind. New onshore wind would be a triple win for consumers, the environment and UK businesses”.

Earlier this year, the trade association Wind Europe reported that onshore wind installations in the UK reached a “record-high” in 2017 as developers rushed to secure subsidies through the Renewables Obligation scheme, which began closing to new projects in May 2016.

Renewable UK expects installations to “drop sharply” in 2018 and 2019 as this booms turns into a bust.

According to Aurora Energy Research, renewables have been left in “no man’s land” due to the lack of clarity over the future of subsidies.

The market intelligence firm said the ramp down of Renewables Obligation and Feed-in Tariff payments would allow the government to offer a further £700 million of annual subsidies by 2030, without breaching its cap on low-carbon levies on energy bills.