Cleaning Solar Panels

Keeping your solar panels working efficiently

How do solar panels work?

The photovoltaic effect, which is the basis of solar panel technology, was discovered in the 19th century, by Edmund Becquerel, a French physicist.  Some materials create a small electric current when exposed to light and photovoltaic or solar panels are made up of small individual cells which produce a small amount of electricity. The greater the panel area, the more electricity is produced.

Solar panels can work on cloudy days as well as bright ones, as the cells react to light rather than heat. The positioning and direction of the panel is therefore important as the closer to south facing it is, the more light it will receive (solar panels generate 47% more electricity on south facing panels than they do on north facing panels). It’s also important to position the panel where it won’t be shaded by trees.

Do you need to clean solar panels?

Just like anything which is exposed to the elements for any length of time, solar panels can get dirty and this will impair their efficiency by up to 20%, which effectively costs money as less electricity will be generated. Even after heavy rain, a solar panel may look clean but rain leaves behind its own residue of dust and dirt.

Each solar panel cell has a glass cover with an anti-reflective coating to protect the silicone membranes within each cell, so it is a fairly delicate piece of apparatus and not one to be attacked with a scouring pad and elbow grease! Whilst solar farms are becoming more familiar sights around the UK countryside, most of us have the panels installed on our roof. This is the best place for them, although it makes access a bit difficult.
So if access is difficult and careful cleaning is required, how do you clean your solar panels? A soft cloth on the end of a stick might work, or hosing the panels, might have some effect, but neither of these is efficient or fully effective.

Pressure washer accessories for solar panel cleaning

A solar panel can be cleaned using pure water technology, which is what many window cleaners now use. “Pure” or demineralised water has had its impurities removed meaning that when it is applied to a surface it will return to its natural state and remove the dirt at the same time. Window cleaners apply pure water using an extending pole with a brush to agitate the dirt from the window and the same principle works for solar panels (with a slightly longer pole of course!).
See more information about pure water window cleaning.

Alternatively, we recommend using a pressure washer, with appropriate accessories to loosen any dirt or debris, without damaging the surface. We have supplied a number of Karcher iSolar accessories for pressure washers, which can be used in conjunction with a telescopic lance and a water softening system. Ranging from the iSolar 400 which is suitable for use on small and elevated areas, to the iSolar800 brush head, designed for cleaning large systems. The iSolar can be used with pure water, e.g. for the final rinse, for an even better finish.

For advice about cleaning solar panels, please give us a call.