Cleaning, solar panels

Cleaning and maintaining your solar panels: an expert guide

Customers often ask us if they should arrange to have their solar panels cleaned. The short answer is that it is unlikely to be worth it. In the UK climate solar panels are largely self-cleaning and deterioration in PV system output due to dust or dirt is rarely detectable, even after 3 years. However, if you are in doubt do ask us to have a look at your generation figures (taking in to account weather variations).

When to clean

Solar Panels are designed to be self-cleaning in the UK, and as such would be deemed to have little to no maintenance at all. In certain situations, such as having panels in a particularly dry area (where dust and bird droppings may build up) or where the panel tilt is less than about 5 degrees, cleaning is recommended to ensure an efficiently generating system.

How to clean

In most cases cleaning of roof mount systems is a job for the professional. But if you have a ground mount system to clean here are some general guidelines.

Safety first – Before working on the panels, we would recommend shutting down the system. Instructions can be found in the schematics provided after the installation. But remember that the roof cabling will still be live can carry dangerous voltages. You cannot turn the sun off!

If you see any damaged cables, stop, and report them.

Roof mounted panels are clearly best cleaned from the ground. If this is not possible, please do not attempt to access the rooftop without appropriate access, equipment, and training.

Cleaning Equipment

A good quality, soft brush and a squeegee with a plastic blade on one side and a cloth covered sponge on the other, with a long extension can make for the perfect tools to clean your panels with. A hose with a suitable nozzle will allow water to reach the panels. If your mains water is hard, harvested rain water would ideally be used as the final rinse as it will leave less residue on the panels.

Cleaning method

Cleaning your panels on an overcast day, early in the morning, or in the late evening. If the panels are warmed by the sun then water can quickly evaporate on the panels and leave marks on the panel.

Early morning can be a particularly good time as the panels will have cooled overnight and morning dew can help to soften any grime leading to less water and effort to clean the panels.

If the panels are dry, use the soft brush to brush any loose dirt before tackling the panels with water. If hard water is all that is available, then be sure to squeegee the panels as well as possible as hard water will form deposits on glass as it dries.

Further Reading

  • In order to know whether your panels need cleaning, you need to know how well your system is performing. Our monitoring platform compares to satellite sunshine data so we can see effect of dirt easily.
  • Cleaning can form part of an overall operations and maintenance package.  We offer O&M services on a reactive or preventative basis
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