Should I clean my solar panels?

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To clean or not to clean your solar PV panels, that is the question. There’s been something of a debate going on around this topic, with some people recommending regular cleaning while others claim it won’t make a difference and that you can even damage the panels in the process. Let’s see if we can shed some light on the pros and cons of solar panel cleaning.

How quickly will my solar panels deteriorate over time?

The durability and output quality of any PV module depends on its build quality. Assuming you’ve invested in a high quality installation, the expected rate of degradation in terms of electricity generation is about 1% per year. So the short answer is yes, but only very gradually.

The key to choosing a quality PV installation is to compare and assess the types of solar panels that are available for your home. Take a look at the data sheets and consult an experienced solar installer who will recommend the best solution for your requirements.

In terms of maintenance, the majority of PV systems have no moving parts, plus their decades-long lifespan means they need hardly any looking after. The most important thing to check is that the panels are free from obstructions and shade, perhaps giving them a routine inspection twice a year to check for damage.

Do clean panels perform better than dirty ones?

There is no doubt that clean solar panels will always perform better, since any significant build-up of dust and dirt can cause a drop in output. Due to the inaccessibility of roof-mounted solar installations in particular, many manufacturers now produce self cleaning panels.

These have a hydrophobic coating that is designed to stop water droplets from sticking to the surface of the panels. The idea is that the rainwater droplets simply roll off the panels, taking any dirt, dust and debris with them.

How much rainfall is needed to keep the panels clean?

In areas such as Southern Europe and North Africa, rainfall is quite low and airborne dust high, meaning a higher build-up of dust and dirt that should be removed by regular cleaning in order to prevent a significant drop in output.

Here in the UK, on the other hand, we’re lucky with our good old British weather! The regular amount of rain we receive all year round is enough to bring the modules’ self-cleaning properties into play. A light layer of dust accumulating over the summer months is only going to have a negligible effect on electricity generation, while a proper shower can even remove bird droppings.

What about flat PV installations?

Rain will wash dirt and dust off solar panels provided they have been installed at an angle of at least 10 degrees. If your solar panels have been fitted so they lie flat, the water has nowhere to go. Pools of water will eventually evaporate, leaving behind a film of grime. Worse still, fallen leaves and other debris will accumulate and cause output problems.

Should I worry about bird droppings?

Bird droppings can cause a lot more problems than simple dust, and they may not always wash away in the rain. The issue may be exacerbated if you have a TV aerial positioned above the panels – perfect for birds to perch on, but unfortunately with predictable results!

Bird mess can cause a reduction in the efficiency of your solar panels, since even a small amount of hard shading can substantially lower output. If this is a problem for your installation, a regular solar panel cleaning regime may be a wise move, along with cruelty free measures to deter the birds from perching.

Do’s and Don’ts for cleaning your PV panels

If you do decide to clean your solar panels, the first thing to do is to check with the manufacturer, in case cleaning has any impact on your warranty. Assuming there’s no problem,

DO

  • Give your panels a simple rinse with a garden hose. You can also use a water fed pole with a soft brush, combined with a squeegee
  • Try a soft brush, sponge or cloth and wipe in small circular strokes to loosen any persistent dirt
  • Use plain water wherever possible, or use gentle cleaning products, making sure you rinse off any detergent and ideally dry your panels with a soft cloth to prevent salt or calcium build-up from the water.

DON’T

  • Use any abrasives – neither tools nor products as these may scratch the protective coating and might mean dirt will build up more quickly in the future – exactly what you don’t want! If in doubt, check with your supplier or use plain water. What’s more, detergents can cause streaks on the panels
  • Clean your panels in hot weather – spraying cold water on very hot panels can cause smudging or, worse, cracking. Morning, evening or cooler days are best for cleaning solar panels.

Finally, if you must clean your solar panels, put your personal safety above all else. If you feel that you cannot safely access your panels for cleaning purposes, then don’t chance it. A small misstep on a slippery roof could not only damage your solar installation, it could result in a fall that could injure or even kill you.

Keep your feet firmly on the ground and use a telescopic brush to clean the panels. Alternatively, hire a solar cleaning company with the correct equipment and knowledge to do the job for you.

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