Solar panels produce electricity from the sunlight striking the cells. This means the more light hitting your PV panels, the more electricity your farm produces. However, left unattended, solar panels accumulate dirt or soiling on their surface, which may impact the quantity of electricity that you generate. In this article, we dive into the importance of PV panel cleaning, including why it is necessary, its benefits, and best practices.

How do solar panels accumulate dirt?

Gleaming newly installed solar panels make for great photos. However, with time, the surface of the panels is covered in a film of dirt. If your farm is located in the UK, the soiling on your photovoltaic (PV) cells can come from several sources:

Airborne dust and particles

Depending on the location of your solar farm, dust particles can be deposited on your PV panels by the wind, pollen, and other environmental debris. With time, these dust particles can grow into a layer that prevents sunlight from reaching the PV panels, affecting the solar power generated by your facility.

Tree and plant sap, lichen, soot, and bird droppings

Solar farms are often sited close to vegetation. This proximity can introduce tree and plant sap that stick to your panels. Other organic materials like lichen and soot may also settle on the surface of your solar panels. At times, birds attracted to the vegetation surrounding your farm are the source of droppings that adhere to your panels and create shadings that block the cells from receiving sunlight.

Rainwater and dust

Rainwater and dust can paradoxically cover your PV cells with dirt. Sometimes, rainwater mixes with fine dust to form a sticky slime. When it dries up, the slime may get heated up in direct sunlight, causing hotspots.

The impact of dirt on a solar panel

Solar farm operators want their PV panels to produce energy at maximum efficiency. However, dirt buildup on solar panels negatively impacts the facility’s output. Some of these are:

Reduced energy production

Dust, soot, and other particulates can reduce solar panel efficiency. A dirt layer reduces the irradiance reaching the cells, thus causing a drop in performance. Studies have shown that soiling can cause up to 4 per cent annual loss in energy production in Europe and up to 7 per cent in the US. This figure could be as high as 50 per cent in the Middle East.

Increased cost of maintenance

Solar panels have to be cleaned regularly for them to continue working efficiently. This maintenance work can attract a one-time cost of about $5,000 for a 10 MW farm producing enough power for 2,000 households daily.

While relatively rare, soiling introduces fire risks on PV panels. This can happen when dirt, bird droppings, or foliage lead to shading, causing hot spots that may lead to burning.

Financial impact

Apart from the maintenance cost of keeping PV panels clean, reduced efficiency can affect the farm’s bottom line. Producing less electricity due to a drop in efficiency means a loss in revenue, estimated to cost Europe up to five billion euros annually. 

Soiling cementation

Accumulated dirt can become much more difficult to remove if left unchecked. This process is known as cementation.

How often should PV panels be cleaned?

The frequency of the PV panel cleaning depends on multiple factors, including the site environment, the panel type, the type of installation, instructions from the manufacturers, etc. However, below are some general guidelines for cleaning your PV panels:

1. Clean your panels at six-month intervals or at least once a year.

2. Farms closer to urban areas or trees will require more frequent cleaning to get rid of dirt and grime.

3. Solar farms in the UK cannot depend on rain to clean their panels.

4. Some solar panel warranty conditions include regular cleaning.

In conclusion, dirt layers on PV panels comes from multiple sources and can cause a drop in the power output of solar farms, in addition to increasing maintenance costs. Dirt should not be allowed to accumulate as it will become even more difficult to eliminate.