How to clean solar panels in a proper way?

Cleansing solar panels

How to clean solar panels in a proper way?

As the owner of solar panels you obviously want to obtain the highest yield possible. Therefore it is important to pay attention to the maintenance process of your PV system.

Think for example of the choices you must make with regard to the frequency and the type of solar panel cleaning. But first, a distinction should be made between preventive and corrective maintenance.


Preventive maintenance implies that you closely monitor the performance of your solar panels in order to prevent your system from certain problems or defects that can cost you money.

In case of corrective maintenance, you should intervene immediately when an error or malfunction occurs. This can for example be compared with a light that is activated on the dashboard of your car when there is an acute problem.


A frequently asked question is the frequency at which your solar panels should be cleaned. Based on our experience we suggest that a single cleaning each one to five years should be sufficient, dependent on the location and other environmental factors.

Cleaning your solar panels too often allows the risk of developing microscopic scratches in the coating, at which little pieces of dirt will attach very soon after the cleaning process.

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Furthermore, the cost of cleaning the average solar panel installation is estimated between 150 and 200 euro. An exception are the solar panels with prism glass, for which a cleaning process averages a cost of 500 to 600 euro.

It should therefore be questioned whether the efficiency gains resulting from the annual cleaning are sufficient to outweigh the costs.


This is also confirmed by our case study in which a pure (reference) solar panel is exposed to various degrees of dirt (sand). As shown in the table below, a slight or moderate amount of dirt results in little or no losses of efficiency. Only for a solar panel with a heavy degree of dirt a significant loss of efficiency is noticed.

Degree of dirt Relative power PV system compared to reference
None (reference)100,0 %
Light99,8 %

 Tabel 1: power relative power PV system as a function of the degree of dirt[/vc_column_text][/vc_column][/vc_row]

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Fig.1: clean (reference) solar panel

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Fig.3: solar panel with average degree of dirt

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Fig.2: solar panel with light degree of dirt

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Fig 4: solar panel with high degree of dirt


In order to obtain the highest efficiency possible you should install a special ‘PIDcoating’ on the glass of your solar panels. This may be in the form of a spray, or by mixing it with the water for the maintenance of your solar panels.

In this way a filter remains on the panels, so that the electric charge quickly ends up in your installation. This ensures, in combination with the installation of the efficiency enhancing PIDbox of iLumen, a faster regeneration of the solar panels affected by PID.

Note that the PIDcoating does only work properly when a PIDbox is installed!



Finally, we would like to warn you for people that offer you the ‘free’ cleaning of your solar panels, preferably on a hot sunny day. By way of demonstration, they clean a number of solar panels which will a few hours later end up in a considerably higher yield. However, these people don’t tell you that the efficiency increase only lasts for a few hours and can only be explained by the cooling effect of water on the heated solar panels. As you know, a high temperature is detrimental to the efficiency of your solar panels.

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