Sir, – I was interested in your figures for the solar power scheme at Longfield School, Darlington, and while the project may be interesting it does not make economic sense.

You say the scheme cost £20,000 and the generated power is 3300KWh/year. At current prices of 10p/KWH that gives a return of £330 per year.

However a modest return on a banking account would be three per cent or £600 per year so not only is there no payback, money is being thrown away.

Unless the equipment can be installed for much less than £1/watt these schemes are not viable.

Dr JOHN E LLOYD Woodland Road, Darlington.