Contractor Blog

Solar Panel Cleaning

George Riley · 30 Mar 2020

One of the questions we hear often is ‘Do I need to clean my solar panels?’. The short answer - it depends. So when should you invest in solar panel cleaning?

Solar cells are coated to be self-cleaning, at least theoretically. For most installations on sloping roofs, this works fine, with rainwater keeping the panels clean. But in certain locations (with high pollution, dust or debris) or on flat roofs, it pays to get your solar system cleaned.

A study by Google found that cleaning horizontal panels increased their output by 36%. Definitely worth the effort!

How to clean solar panels

The most important thing when cleaning solar panels is to be as gentle as possible, since even tiny scratches can develop into greater damage to the solar cells. This is one of the reasons we recommend calling in professionals rather than attempting it yourself.

The main steps involved in solar panel cleaning are:

  • dusting off any loose debris like fallen leaves;
  • lightly scrubbing and rinsing off dust, pollen and dirt;
  • wiping the panels dry.

    Your regular window cleaner can usually clean your residential panels:
  • Do ask them to be careful as the panels shouldn't be damaged.
  • They should be able to clean them with just water and a light scrub.

    How can they access the panels for cleaning depends on the type and height of roof:
  • For residential and sloping roofs, they can normally clean the panels from ground level with no need for scaffolding or access equipment. They reach the solar array with a low pressure washer and lance.
  • For commercial and flat roofs, there will often be access already in place. They may use mansafe harnesses to protect our workers.
  • Otherwise, they may use a cherry picker if feasible.

Do you need a professional for cleaning or can you do it yourself? We would recommend opting for a professional cleaning service as working at roof height is a safety risk. It’s also not worth damaging your panels inadvertently through incorrect methods (e.g. leaving microcracks on the cells).

How often should you clean solar panels?

If your panels are on a sloping roof, dust and dirt are generally washed off by the rain. The exceptions are if you live in a high polluted area or notice stubborn debris building up (e.g. bird droppings).

If your panels are on a flat roof (or one of the exceptions above), we recommend cleaning every 1-2 years. This should be sufficient to keep your panels performing at their optimum output.

The best time for cleaning is spring. You’ll remove any winter debris and pollen to get the panels in the best condition possible for the months when daylight hours are longest.

The future of solar panel cleaning

There is a lot of innovation happening in the world of solar panel cleaning, particularly when it comes to industrial scale solar farms. Many of these are in remote areas like deserts, chosen for their high levels of solar insolation. This is great for power generation but less so for:

  • high dust build up,
  • shortage of water for cleaning,
  • difficulty and cost of access and maintenance.

So researchers are experimenting with automated solutions, such as waterless inbuilt wiping arms and drone airflow. Both of these have the potential to bring down the cost of running solar plants, making this renewable resource ever more economical.

Solar PV in desert

Other solar PV maintenance

There are two other elements of solar panel maintenance worth bearing in mind:

  • Electrical servicing - just like any electricals, solar PV systems should be tested periodically for faults, fire risks and to ensure optimal performance. We recommend every 2 years.
  • Inverter replacement - as a whole, PV systems are expected to last 25+ years. But the inverter will generally need replacing after the first 10-12 years since it has such an intensive role.

Topics: Maintenance, Solar PV