Europe Solar Utility (ESU) has announced the sale of one of the last solar PV installations to be completed under the UK’s previous feed-in tariff, to an undisclosed investor. The three installations, which total 3.7MW, have been built on land owned by water regulator Thames Water. The area is equivalent to ten football pitches and will generate up to 3,500MWh – enough to run around 750 homes, saving Thames Water around £100,000 a year.

Construction of the projects was financed and managed by ESU, successfully completing the first phase of the project before the August 1, 2011, deadline qualifying it for the higher feed-in-tariff rate of £0.307kWh. The installation will provide 0.5% of its 1,180GWh – £80m annual energy requirement – for processing and transporting 2.6 billion litres of water a day and more than 4 billion litres of sewage a day – in addition to the 16% already generated from burning biomethane gas derived from sewage sludge using anaerobic digestion.

ESU will be involved in the on-going management of the installations to ensure optimal performance.

“We delivered this project in the nick of time, keeping alive our goal to become Britain’s biggest on-site producer and industrial user of solar power, and further hedging ourselves from future upward fluctuations in the mainstream, non-renewable energy markets,” said John Gilbert, Thames Water’s head of carbon and energy management.

Patrick Charignon, CEO of Europe Solar Utility, said: “Future projects of this scale have been put in doubt by the UK Government’s proposed cut to the feed-in-tariff rate. However, utilities may still gain the benefits of solar PV through installations built around power purchase agreements of the type used in this project that offer long-term price certainty in environment of rising energy prices.”

Under the 25-year contract, Ennoviga Solar Ltd has created an investment company that will own and maintain the solar arrays, repaying the investment by selling all the clean electricity produced to the water company at a market-competitive price.

Stefano Gambro, director at Ennoviga, said: “By working with us, Thames Water has led the industry in exploiting otherwise unusable space to generate clean electricity. When energy prices rise and carbon charging starts, the impact on Thames Water customers’ bills will now be that little bit less.”

The locations of the Thames Water’s solar arrays include: 450kW, generating 385MWh a year on average, on the roof of the Beckton desalination plant in Newham; 1,500kW, yielding on average 1,400MWh a year, on the top of vast storm tanks built in the 1800s at Crossness sewage works in Bexley and 1,790kW, producing 1,550MWh a year on average, on redundant sand filters at Walton water treatment works in Sunbury.