Keeping your solar panels clean and free from dust, mould and bird droppings will help to produce more energy giving you a greater return on your investment, I would recommend having them cleaned at least once or twice year.
The best method to clean from the ground using water fed poles and pure deionized water leaving no hard water marks and drying completely clear.
The manufacturer that installs solar panels recommends having them cleaned to improve efficiently, so it is defiantly worth spending on to get maximum return.
