Tesco and Shell are to buy the entire output of a controversial solar farm under construction on the Kent coast that was originally meant to power 100,000 homes.

The two companies have signed deals to purchase all the electricity generated by Cleve Hill, which is poised to be the UK’s largest solar farm when it goes into operation early in 2025.

The project won planning permission despite massive local opposition on the basis that it would power more than 100,000 homes. However, 65pc of the output has instead been purchased by Tesco, which says Cleve Hill will help it cut emissions by powering up to 144 of its supermarkets.

The remaining 35pc of output will be managed by Shell as it buys up sources of renewable electricity to power its growing network of EV charging stations.

Vicky Ellis, of the Kent branch of CPRE, the countryside charity, said: “This project was approved on the premise that it would power homes, not petrol stations and supermarkets.

“The irony of a major supermarket such as Tesco and a prominent oil producer such as Shell buying into the green energy market to run their petrol stations and supermarkets is not lost on us. We suspect this is another example of greenwashing.”

Cleve Hill is owned and financed by Quinbrook Infrastructure Partners, a US investment fund based in Houston, Texas, which specialises in energy projects.

The 860-acre scheme is being built near Faversham on the Graveney salt marshes, once renowned for its wildlife, especially many wetland bird species. The site is also surrounded by nature reserves.

The solar farm scheme has already generated years of protests. It was rejected locally but was finally approved by Alok Sharma, then energy secretary, in 2020.

The marshes are now being covered in 560,000 solar panels, creating a total capacity of about 373 megawatts (MW). Some panels will be built on steel frames almost the height of a double decker bus because of the flood risk. Batteries to store any surplus power generated will also be installed.

Cleve Hill’s capacity will be equivalent to half the output of a small gas-fired power station or a ninth of the output planned for the UK’s next nuclear power stations at Hinkley Point, Somerset, and Sizewell in Suffolk.

The project divided environmental groups, with Friends of the Earth welcoming it but the Campaign to Protect Rural England (CPRE), Kent Wildlife Trust and the RSPB opposing it.

Ms Ellis, who also lives near the site, said the CPRE supported green power projects but not at any price. She said: “Graveney Marshes is an extremely special place. It is flanked on three sides by protected nature reserves and was afforded high landscape value by Swale borough council.

“One could stand on the marshes and without moving watch the sun rise and set with its open panoramic views towards Sheppey, Whitstable and parts of Faversham. It was one of the last tranquil places around Faversham with incredible views of the night sky. And now it’s gone.”

Tesco said the 15-year power purchase agreement signed with Quinbrook would help green its stores. The addition of Cleve Hill to its portfolio meant power purchase agreements would now cover 45pc of Tesco UK’s expected 2030 electricity demand.

Ken Murphy, Tesco’s group chief executive, said: “Cleve Hill solar park, with its ability to generate up to 10pc of our UK electricity demand, joins a number of other Power Purchase Agreements we’ve announced over the last five years.”

UK’s largest solar farm

Keith Gains, the UK regional lead at Quinbrook, said: “Quinbrook is proud of developing Cleve Hill as we believe it is a blueprint for the next generation of energy transition infrastructure in the UK.”

Shell, which trades in both electricity and renewables certificates, has signed a 10-year agreement with Quinbrook to manage the 35pc of Cleve Hill’s output that is subject to a government contract for difference.

Such contracts guarantee the supplier a minimum price for any power generated, with the price rising in line with inflation – key attractions for investors.

Shell runs about 1,000 forecourts in the UK selling petrol, diesel and, increasingly, offering electric vehicle charging points. It boasts that all the electricity used to charge vehicles comes from renewable sources.

Rupen Tanna, the head of power and systematic trading for Shell Energy Europe, said such schemes were an important part of the UK’s net zero ambitions.

Cleve Hill will be the country’s biggest solar farm by capacity when it comes online. However, Ed Miliband, the Energy Secretary, has approved several large-scale solar farms since the election that will eclipse it when they become operational. The largest so far is the 600MW Cottam project in Lincolnshire, along with the 500MW Gate Burton project also in Lincolnshire and Sunnica scheme in Suffolk.

Chris Hewett, the chief executive of Solar Energy UK, said the industry planned a three-fold expansion by 2030.

He said: “We can expect to see more deals such as these in the coming years, as the industry scales up to reach 50 gigawatts of generation capacity by 2030.”