A massive solar farm, which would be one of the biggest in England, could cover half the former RAF Coltishall site, with a mystery developer in talks with council bosses about the proposal.

Norfolk County Council bought the former air base for £4m in January last year and, as part of its vision for what might happen at the 600 acre site, a 50 acre solar farm was proposed.

But, the council says further investigation has established that, with the electric supply grid in Norfolk at capacity, the necessary 22km cable to connect the Coltishall site to Norwich would cost millions of pounds.

That makes a small scale farm unviable, according to council officers, so to recoup investment a much larger scheme would be needed.

And a renewable energy developer has approached the council seeking a 25-year lease on up to 300 acres (120 hectares) of grassland to run a large scale commercial solar farm.

At a size of about 170 football pitches, it would be the biggest in Norfolk and one of the largest in England.

Taking up half the site, tens of thousands of photo-voltaic panels would generate 60 megawatts of energy - enough to power more than 18,000 homes for a year.

The council says it cannot reveal the identity of that developer - or how much such a scheme would cost - for commercial reasons. But they have drafted in specialist advisors from Deloitte to help officers carry out due diligence on the proposal.

George Nobbs, leader of Norfolk County Council, said: 'This is an exciting prospect for several reasons. Clean solar energy is one of the few things that has near universal acceptance, and solar farming, although not the traditional type of farming we are used to in Norfolk, does have the advantage of not permanently altering the geography and nature of the landscape - indeed, I'm assured that sheep can safely graze under the solar panels.

'I very much hope that this project will pay dividends and deliver both clean energy and a healthy return on the council investment.'

Tom McCabe, interim director of environment, transport and development, said: 'The potential to have solar panels on the Coltishall site has been the subject of public discussion for some time and is a hugely exciting prospect.

'Producing 'green' electricity would generate much needed recurring income for the county council for 25 years at a time when grants from central government are being cut.

'As the site is not in open countryside we very much hope it will also be generally acceptable to members of the public and to the relevant planning authority when the time comes.'

The controlling Labour/Liberal Democrat cabinet at County Hall will decide on Monday, May 12, whether to increase the scale of the solar farm originally envisaged in the council's development vision for the Coltishall site.

That vision also includes new homes, commercially rented buildings, county farm tenancies and a heritage trail. Lafarge Tarmac has also applied to dig up the ends of the runway to create aggregate - a proposal which has sparked controversy in nearby villages and an objection from English Heritage.

The area available for farm tenancies would be 'restricted' if the solar farm proposal goes ahead.

The county council was quick to stress that much of the land in question lies within North Norfolk District Council, so councillors for that authority, rather than at County Hall, will determine any planning application.

While the developer would make the money from the sale of power to the National Grid, the county council would receive the rent for the land.

In December, the go-ahead was given to Good Energy to install a solar farm on about 91 hectares of land at the former RAF Raynham site, near Fakenham.• What do you think of the former RAF Coltishall site being used for a solar farm? Write, giving full contact details, to Letters Editor, Prospect House, Rouen Road, Norwich NR1 1RE.