What's the most effective and safest way to clean solar panels?

March 14, 2018

Soft washing solar panels is a great market. Think of the acres of panels that are popping up in farmer's fields all over the country, as well those on the roofs of houses, factories and offices.

All need professional cleaning.

Are solar panels self-cleaning?

Well, it is true that the majority of solar panels are promoted as being self-cleaning, and so should require relatively little additional cleaning.

However, "self-cleaning" is a bit of a misnomer, like "self-cleaning" windows. For sure they don't need cleaning so frequently, but they do need regular cleaning to remain efficient producers of electricity.


Quick tip: Grime, bird poo and heavy dust don't need to cover an entire solar panel to have a negative effect on it's performance.

In certain situations, such as solar panels mounted in a particularly dry area (allowing dust and bird droppings to build up), or where the solar panel's tilt angle is less than five degrees, most manufacturers recommend regular cleaning to ensure the panels continue to work efficient as electricity generators.

What type of water should you use to clean solar panels?

Solar  panel manufacturers suggest that using water devoid of detergents – ideally de-ionised – will be sufficient for cleaning most solar panels, most of the time.

Manufacturers strongly recommend not using detergents that can cause streaking and thus compromise the effectiveness of the panels. 

Quick tip: Window Cleanze does not leave streaks and so is suitable for cleaning solar panels. Just add a few drops of Benz Window Cleanze to your de-ionised water.

A window cleaning WFP (water-fed pole) set-up using de-ionised water is the best way to clean solar panels. And adding a few drops of Window Cleanze to your de-ionised water will help to quickly remove bird droppings and spider poo. 

What is "pure" water? This is a generic term used to describe de-ionised water and distilled water. Both could be called "pure" but are produced through different processes.

Distilled water is usually produced in large industrial settings, while de-ionised water is the water produced on a daily basis by us and by the vast majority of water-fed pole (WFP) window cleaners.


Can you use tap water to clean solar panels? We do not recommend using ordinary tap water because it is mostly anything but pure. It can leave deposits and smears on the solar panels that will reduce their efficiency.

Soft water will not cause as much of a problem, although we do not recommend using even that, and advise against using hard water whenever possible.

Quick tip: In hard water areas* it is crucial to wipe all such water, if used, from the solar panels before they dry, to prevent limescale/calcium building up.

* Ideally, don't use hard water on solar panels at all.

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