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July 4, 2024

How To Clean Solar Panels

Cleaning solar panels

When did you last clean your solar panels? Many householders don’t realise solar panel cleaning can play an important role in getting the most from their investment in free, green electricity. Solar panels work more efficiently when they’re clean. Dirt that builds up on the panels reduces power output and limits the financial benefits of solar energy.

Keeping rooftop solar panels free from dirt helps ensure they’re doing their job properly and prolongs their lifespan. And solar panels only need cleaning occasionally. 

But what’s the best way to clean solar panels? Find out here along with everything else you need to know about solar panel cleaning.

How Dirt Affects Solar Panels

Dirty solar panels aren’t just unsightly; they prevent daylight from reaching the solar cells. This reduces system performance as the panels produce less electricity from the sun’s energy. Most solar arrays are only as efficient as the lowest-performing panel. If just one solar cell is affected by dirt, the whole system will suffer.

Deposits that can accumulate on solar panels include:

  • Airborne dust particles. 
  • Soot.
  • Pollutants from traffic.
  • Bird droppings.
  • Tree pollen.
  • Sticky sap from trees.
  • Fallen leaves and twigs.
  • Moss, lichen and algae.
  • Sand and sea salt in coastal areas.

Problems Caused By Dirt On Solar Panels

Dirt that accumulates on solar panels can cause several issues affecting energy efficiency and production.


The shading effect of dirt on solar panels impacts energy efficiency. Research has shown that even a thin layer of dirt can reduce electricity output by 5 to 25 percent.

Solar Panel Corrosion

Bird droppings and other types of acidic organic matter can cause corrosion. Over time, this can degrade the protective coating of solar panels and possibly damage the underlying solar cells.

Panel Hotspots 

Heat may be distributed unevenly across dirty solar panels. Some solar cells might remain cooler while others heat up. This can create hotspots that impact the performance and lifespan of the solar panel system.

Structural Damage To Panels

A substantial build-up of dirt can place weight stress on solar panels and their supporting structures. This can lead to structural damage.

Pest Problems

Accumulated debris, particularly organic matter, provides a breeding area and nesting material for rodents, birds and insects. This can damage the solar panels, their supporting structures, and wiring.

Moisture Retention 

Thick layers of organic materials can trap moisture on the surfaces of solar panels. This increases risk of water damage, mould growth, and corrosion.

Solar Panel Cleaning Tools And Materials

Tools and materials you’ll need to clean your solar panels are:

  • Extending soft-bristled brush. 
  • Garden hose with spray attachment.
  • Soapy water in a one-gallon (4.5-litre) handheld sprayer.
  • Sponge, soft cloth or towel. 
  • Squeegee on extension pole.


If you’re going to access the roof to clean your solar panels, you’ll also need a ladder and non-slip footwear. 

Solar Panel Cleaning Step By Step

Whether you clean your solar panels from the ground or at roof level, the materials, equipment and method are basically the same. Here are the steps you need to follow.

  1. Remove leaves and other loose debris with the extendable brush.
  2. Spray the panels with a light stream of water from your hose.
  3. Apply a thin layer of warm soapy water from your handheld sprayer to a small area of one panel.
  4. Wipe off the soapy water with a sponge, towel or large cloth wrapped around the extendable squeegee.
  5. Repeat the above two steps for the rest of the panel. Then move on to the next panel. Continue until you’ve cleaned all the panels.
  6. Hose down the panels again for a final rinse.
  7. Use the squeegee to remove remaining water from the panels.

Safety Considerations When Cleaning Solar Panels

Personal safety should always be a priority when cleaning solar panels. Unless you’re experienced with rooftop work and have the right equipment, you may find your roof is too high or too steep to access to clean your solar panels safely. If you’re in any doubt, don’t go up on the roof. Clean the panels with your feet firmly on the ground. 

If you’re absolutely confident about getting up on your roof to clean the solar panels, make sure your ladder is safely positioned with someone at the bottom to hold it in place. 

Whether you’re going to clean your solar panels from the ground or by using a ladder, switch off the system first. Otherwise, you risk getting an electric shock and damaging the panels. Avoid handling wiring or the underside of the panels as you work.

Why Bother Cleaning Solar Panels?

Solar panels are largely designed to be self-cleaning, with dirt being washed off by rainwater. They have a protective, hydrophobic coating that prevents water droplets from adhering to the surface of the panel. As the droplets fall away, they take dust and dirt with them.

However, in order to maintain efficient solar panel performance, additional cleaning is still needed in many circumstances, such as:

  • You live in an area that gets less rainfall.
  • You’re surrounded by a large bird population, with a high incidence of droppings.
  • You live in a city or large town, where air pollution tends to be worse.
  • Your home is near a busy road.
  • Your home is surrounded by tall trees, so there’s a higher risk of leaves, pollen and sap ending up on your panels.


In these situations, cleaning your solar panels will ensure optimal light absorption and higher energy output. It will also improve the durability and longevity of the panels.

Solar Panel Cleaning Do’s And Don’ts 

As with windows, you should avoid cleaning solar panels on a hot day when the sun is shining directly on them. The tempered glass of the panel surface will dry too fast, leaving streaks.

The best time to do the job is early morning. Morning dew can form on the panels as they cool overnight. This softens build-ups of dirt so the panels are easier to clean, using less water. Alternatively, clean your solar panels early in the evening or on an overcast day.

Avoid using abrasive cleaning materials and the harsh chemicals found in many household cleaning products. These may damage the panels. Instead, use soapy water made with a mild washing-up liquid.

If you live in a hard-water area, you may want to consider collecting rainwater to spray on your solar panels for the final rinse. It will leave less residue on them. If you do use hard water, make sure to squeegee the panels as thoroughly as possible to prevent deposits forming on the glass as it dries.

Don’t use a high-pressure washer. While solar panels can withstand heavy rain, direct high water pressure can damage seals around the frames, allowing water to get inside the panels and causing damage.

If you’re getting up on the roof to clean your solar panels, don’t walk on them. 

How Often Should You Clean Your Solar Panels?

There’s no hard and fast rule on how frequently solar panels need to be cleaned. Because of rainfall levels, most residential solar panel systems in the UK don’t need regular heavy-duty cleaning. If you visually inspect the panels from time to time, you’ll know they need cleaning if you see a build-up of dirt.

In general, solar panel cleaning is recommended once or twice a year to help maintain optimal performance. Panels on roofs with steep pitches generally need to be cleaned less often.

What Time Of Year Should You Clean Your Solar Panels?

Spring or autumn can be a good time to clean solar panels. Winter weather can result in dirty panels by the start of spring, when you should begin to get more electricity output. Cleaning the panels at this point will help you get the most from them.

If dirt build-up such as bird droppings during the summer months isn’t being removed by rainwater, consider cleaning the panels at the start of autumn. This will ensure the panels are working to the best of their ability during the shorter days of autumn and winter.

Professional Solar Panel Cleaning

Cleaning solar panels requires a fair amount of effort. It’s also time-consuming and may take several hours depending on the number of panels. Doing it from the ground can be difficult and at roof level potentially dangerous.

If you’re unsure about the DIY approach, a professional can do the job faster and more thoroughly. A solar panel cleaning service will have cutting-edge equipment and know the specialised techniques needed to maintain your panels in top condition.

Solar panel installer Effective Home can advise you on the best way to keep your panels clean.

Build Your Solar Quote Today

Justine Effective
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