Government minister Ed Vaizey has pledged to be among the first to invest in the unique Westmill Solar Cooperative - the wind farm on the outskirts of Swindon.

Mr Vaizey, Minister for Culture, Communications and the Creative Industries, officially launched a share offer which will allow people to buy a stake in what could soon be the world’s largest community-owned solar power station.

Hundreds of people from across the UK attended the launch which was part of an energy and sustainability fair held at the site of the solar farm at Watchfield.

“I am sure I will be one of the first investors,” Mr Vaizey said.

“To secure my children’s future for their sakes, both financially and ethically. This site is a physical manifestation of what we have which can change the planet for the better.”

The solar farm was constructed last year and houses more than 21,000 polycrystalline solar panels producing 4.8GWh per year - enough to meet the average annual electricity requirement of 1,400 homes.

Although the site was constructed by seed investor Blue Energy, the aim was always to turn it into a cooperative similar to the Westmill Wind Farm Cooperative which has five wind turbines on the same site.

The solar share offer is now open until of July and anyone can apply to be part of the cooperative. The minimum investment is £250 right up to £20,000 maximum. It’s hoped to raise around £4 million equity. A bond will also be secured to raise the balance to repay the £15m cost of construction.

For the first time, Westmill Solar Cooperative’s directors can reveal they expect investors will get an annual average return on investment of 11 per cent a year for the 24 year period.

In detail, in the first eight years returns should average nine per cent a year, rising to 22 per cent annually in the second eight-year period, then up to 43 per cent a year in the final period. The lower rates take into account the original capital costs as well as those of launching the share offer itself. Investors will also receive their capital back in full over the life of the 24-year project. Details are available for download on at Part of the solar farm’s income will come from the government’s feed-in tariff which is index-linked and therefore rises in line with inflation. As the site was generating clean energy before August 1 last year, the project benefits from the highest possible rate of tariff.

One of the directors of Westmill Solar Cooperative is farmer Adam Twine who has a track record in creating this kind of large-scale cooperative. He founded Westmill Wind Farm which is now in its fifth year. He hopes both projects will inspire other communities to take the lead in clean energy generation.