Letter: Editor's pick: Blackbird pooping in the dead of night

From John Davnall, Manchester, UK

You mention carbon pollutants as a specific problem inhibiting solar panel output (1 July, p 7). I find that sand, wind-eroded topsoil and salt left by fine sea spray are also detrimental.

A particularly insidious problem, however, is bird droppings. My 6-year-old photovoltaic panels consist of strings of cells. If one cell in a string is obscured, that string will not function. In my small system, one well-aimed splat will wipe out one-third of a panel and 3.5 per cent of total output.

Washing works. Earlier this year, a complete wash improved output by 13 per cent when one splat and general dirt were removed. I see no evidence that annual washing has reduced performance.

I am rather surprised that panel-cleaning businesses have not sprung up to cater for the domestic market since panels are almost always on roofs too high for many people to feel safe accessing them.

I am tempted to suggest a solution to the bird problem for solar farms: site them near bird-culling wind turbines. I do fear the reaction…