Two years on and my solar panels need cleaning. It seems that the tree at the front of the house has caused algae to cover the panels which are on the rear of the house. Photos show when originally installed and a detail from this month.
Can anyone recommend a professional solar panel cleaning company? The panels are at high level.
Thanks
Any relatively loose dirt can me washed off with a telescopic pole of the type used by window cleaners. Lichen or bird lime may need specialist treatment.
You need to ask yourself what the value of lost electricity is compared with the cost of specialist cleaning, which may include the cost of scaffolding. 
Unfortunately I can’t recommend anyone. My first array, from 2006, still doesn’t need cleaning.