Photovoltaic systems are exposed to the weather 24 hours a day. Not only rain, but wind, snow, or sun also affect the modules. Pollution from air pollution, dust, road traffic, bird droppings, falling leaves, or needles from nearby trees can take a toll on solar panels over time.
The cleaning of photovoltaic systems is a frequently discussed topic in the photovoltaic world. Some experts swear by the regular cleaning of photovoltaic modules, others consider cleaning to be ineffective and only see it as an unnecessary cost factor. We clarify when module cleaning makes sense and what you should consider.
Dirt tends to settle at the transition between frame and glass, and over time even lichen or moss can settle here. All of these factors definitely lead to lower yields from the photovoltaic system. Cleaning from time to time helps to avoid hot spots and to secure the yields of the photovoltaic system in the long term.
Need cleaning despite snow and rain?
Again and again, the cleaning power of rain or snow for the solar modules is pointed out. There is no doubt that a heavy downpour helps to wipe off superficial dirt such as leftover leaves or dust. Even snow that eventually slides down from the solar modules can pull a lot of dust and light dirt with it.
However, this definitely does not apply to encrusted dirt, for example highly caustic bird droppings baked on in the sun. And the same does not apply to dirt that settles on the edges of the module frames. In addition, the cleaning effect of rain and snow decreases sharply as the angle of inclination decreases.
For Central European locations, the self-cleaning of the modules begins at inclinations greater than 12°. However, regular manual cleaning can significantly increase system yields, depending on the location. In various studies, depending on the location, it is assumed to be between 2% and 7%.
Why do photovoltaic modules get dirty?
In order to achieve the highest possible yield, photovoltaic modules should be aligned directly to the sun and are therefore usually mounted on the roof of a house. They are therefore exposed to the elements just like windows. Fine dust, bird droppings, leaves, or needles can settle on the module surface and soil the modules.
Does pollution reduce the yield of a photovoltaic system?
Basically yes, because dirt can cover part of the solar cells. The effect is then similar to that of shading: Little or no sunlight can be absorbed and converted into electricity in dirty areas. The total yield of the system decreases.
Cleaning preparations for solar systems
But how should the solar modules be cleaned? Just this: you can do a lot wrong. But if a few simple rules are followed, cleaning can really help ensure long-term yields.
The following points should be observed:
- Never use high-pressure cleaners, they could damage the frame, attachment, or the glass of the solar modules.
- Use gentle cleaning agents – do not use highly caustic or harsh cleaning agents. Some solar module manufacturers provide information on which cleaning agents are suitable for their operating instructions.
- Limescale in the water prevents limescale and streaks.
- A soft brush/sponge supports the cleaning power, as does running water.
Costs for cleaning solar systems
There are now service providers specializing in the cleaning of photovoltaic systems everywhere. Of course, the price expectations vary not only regionally, but also from provider to provider. Between 1 and 2.50 euros per square meter of the photovoltaic system should be set. However, apart from a few exceptional cases, a solar system does not have to be professionally cleaned every year. Only systems that are exposed to extremely high levels of dirt due to agricultural operations with heavy dust generation or other industrial systems or due to their location on busy roads should be cleaned at least once a year.
And why not do the cleaning yourself?
In fact, there is nothing wrong with cleaning the solar system yourself. Corresponding material is now easily available on the Internet. The most important tool for do-it-yourself cleaning of the photovoltaic system: is a soft cleaning brush with a telescopic rod. Add a gentle biological cleaner and running water (e.g. via a garden hose) – and the necessary equipment is ready.
However, the accessibility of the photovoltaic system can be an argument against cleaning it yourself. Are all solar modules easily accessible through a roof window or other options using a telescopic rod – okay. If this is not the case, the advice is: Better keep your hands off it. Nobody should underestimate the risk of falling.
It is advisable to have your own photovoltaic system cleaned by a professional specialist company if it is installed on a house roof. Because working on the roof is associated with considerable dangers without training and a head for heights. In any case, the necessary safety precautions must be taken.
If the system is on the ground, cleaning it yourself is less of a problem. But here, too, care must be taken not to touch any components that conduct electricity.
Practical tips for cleaning
Basically, the following applies: Clean the photovoltaic system as gently as possible. Do not use strong detergents, instead use environmentally friendly household or glass cleaners. It is best to avoid using detergents altogether. A soft glass brush is suitable as a cleaning tool, which prevents damage to the glass cover of the modules. High-pressure cleaners, on the other hand, can cause cracks and fissures in the glass surface.
It is also not advisable to use water from the tap. Depending on the degree of hardness, tap water can lead to limescale deposits on the module surface. Therefore, prefer normal rainwater from the rain barrel.