Dirt and filth on solar modules reduces the yields of photovoltaic systems, and economic damage occurs. Regular PV cleaning is a solution with various possible processes.

The fact that impurities on solar plants lead to reduced yields are also shown by the first results of the PV cleaning study for solar plants currently being carried out by Milk the Sun. Due to the reduced light coupling the yields of the system are reduced, so regular cleaning is recommended.

Different sources of pollution

Depending on the location, different sources exist for plants and correspondingly different degrees of pollution. Bird droppings, seasonal pollen, industrial fine dust or aerosols (especially in stables) adhere to the modules – an effect which is intensified in the summer thanks to heated modules. Once a dirt film is established on the modules, further dirt settles faster.

For thorough cleaning, water (often heated), surface-friendly detergents and the right technique are used to soak and dissolve the dirt. Depending on the contamination, different cleaning agents are required (e.g. alkaline or acidic).

Manual, semi-automatic or fully automatic cleaning systems

For small, easily accessible systems, manual cleaning is acceptable. The systems used for it are based on those for the cleaning of glass surfaces on buildings, but for large areas and heavy pollution, they quickly reach their limits.

Semi-automatic systems are a popular choice. They use either water or electric drives as a power source and are a good choice for larger plants due to high efficiency and effectiveness. The higher water throughput of the water-driven systems, which clean with high pressure, usually achieve a higher surface performance than electrical brushes.

Fully automatic cleaning systems are now offered by some suppliers, and extensive testing is still pending in many areas. Freely moving robots or cleaning systems attached to the module carriers take over the cleaning of the photovoltaic system.

Important for all PV cleaning: Safety precautions

Photovoltaic systems produce electricity, which is why voltage-carrying components are located throughout the entire system area. Safety therefore always plays an important role in PV cleaning. In the case of roof systems, additional dangers are to be expected, which is why special safety precautions must be taken in order to avoid falls.
Larger PV plants, as well as systems that are difficult to reach, should be cleaned by qualified cleaning companies, such as the cleaning experts at Milk the Sun.