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Should I clean my solar PV panels?

Posted by Sam Tonge on 12 September 2018 at 10:15 am

Following the recent spell of dry weather in much of the UK, we’ve had a number of enquiries about whether it’s necessary to clean your solar PV panels to make sure they remain as efficient as possible.

A quick Google search for ‘solar panel cleaning’ pulls up a long list of adverts for specialist cleaning firms. However there is an ongoing debate between owners of solar installations in the UK as to whether the periodic cleaning of panels is actually necessary or even beneficial to increase output.

We recommend you consult with your installer for exact maintenance requirements before you commit to installing a solar PV system. It’s also worth mentioning that a reputable installer will provide you with good quality products they know will last the distance, as they are ones to be called back in the event of a fault.

Up above

Many installers now offer arrays that use self-cleaning panels.  These have a specialist coating which stops water droplets from sticking to the surface. Instead they roll off of the panels taking dirt and dust with them.

For existing micro-generators in the UK, our temperate maritime climate means that roof-mounted systems tend to be self-cleaning. This is because rain-water washes away the majority of the dirt and debris that would otherwise accumulate on the panels. A good shower should even wash away leaves and bird droppings that may have accumulated. Cleaning only becomes more of a requirement if your panels accumulate a lot of bird droppings or debris, or in Mediterranean climates where there is little rainfall and a lot of airborne dust, meaning a layer of dirt will build up on the modules causing a drop off in generation.

Remember that the performance of solar panels does fall off gradually over their life time in any event so some reduction in output should be expected.  This degradation is usually highest in the first year (around a 2% reduction in performance would be normal) and more steady in the following years at less than 1% per annum.  After 25 years you should still expect your panels to be producing at least 80% of the electricity they generated when they were new. The data sheet for your solar panels will provide more information on this.

If you feel that cleaning solar PV is necessary and you feel comfortable taking on the task yourself, make sure to consult our guide which covers do’s, don’ts and safety considerations. If you’re looking at using commercial cleaning services, try and calculate whether the cost of cleaning is worth any increase in PV generation afterwards which is likely to be small. 

Down below

In most existing solar PV installations (before the invention of in-roof technology), a small gap exists between your roof tiles and your panels to allow space for electrical equipment and cables and to ensure your panels don’t overheat.

This inadvertently provides a suitable home for rodents such as the Grey Squirrel, and more commonly, urban bird species such as the Feral Pigeon (Columbia Liva). Pigeon droppings on and around your solar PV is likely to have a corrosive effect on your roof tiles, particularly on older properties. The area underneath the panels can also be damaged as a result of nesting, as Pigeons can dislodge wiring and even stop the solar panel system working altogether.

We suggest that the best way to avoid the issue is to ask your installer what you can do during the installation process, in order to avoid becoming the neighbourhood Pigeon hub in the first place.

For existing micro-generators, there’s a whole host of pest control companies out there offering their own solution to the problem. However we suggest that you check first whether any attempt to remove Feral Pigeons and any other critters from your rooftop will be done in a way that is legal, humane and not unnecessarily harmful to local wildlife – see our guide on how to deal with pigeons under the panels.


Do you clean your solar PV panels? Take our 10 second poll to let us know.


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About the author: Sam joined YouGen in 2017 as a Project Officer, after having achieved a BSc (Hons) degree in Geography from Royal Holloway, University of London. 

He is passionate about renewable energy and sustainability and has undertaken a variety of placements focused in these areas. 

Sam coordinates the YouGen blog, newsletter and recommendation service on behalf of installers, as well as driving the platform forward through an active social media presence. 

If you have a question about anything in the above blog, please ask it in the comments section below.

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