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Lichens on solar systems! How that already sounds....
Lichens are always a huge problem for service providers and owners of solar installations. Even if these little "friends" are relatively rare - although we often hear about the cases where they do occur - they are still a huge problem for the appearance and, in the long term, for the performance and substance of a PV and solar installation. At the same time, the best way to prevent lichens is to prevent them from forming in the first place! How can this be done? Through regular cleaning, especially on exposed systems with a corresponding tree population or corresponding climatic conditions that promote lichen growth.
We will discuss this in the following text:
- What are lichens?
- Why do lichens adhere so well to substrates?
- When and where do lichens grow on PV and solar installations?
- Why is lichen a problem on solar installations?
- How can lichens be removed - small spoiler: There is only one solution and it comes from Cleantecs!
- As a service provider, what do I need to look out for when cleaning a solar system with lichen?
1. what are lichens?
Lichens are a unique symbiotic life form consisting of a collaborative relationship between fungi and algae or cyanobacteria. This life form is referred to as "lichen" in English. Lichens are able to survive in extreme conditions, including in regions with extremely low temperatures, on rocks, trees and even on the ground - or even on PV and solar panels.
In the symbiotic relationship, the algae or cyanobacteria produce nutrients through photosynthesis, which serve as a source of energy for both themselves and the fungus. The fungus protects the algae or cyanobacteria from environmental influences and enables them to survive in different habitats. Lichens can appear in different shapes and colors and are often found in nature and are also frequently encountered during PV cleaning or solar cleaning. This symbiotic relationship between fungi and algae or cyanobacteria makes lichens pioneers in colonizing hostile environments and allows them to grow in places where many other organisms could not survive. A PV system is actually one such place. It gets extremely hot, is extremely slippery and also very low in nutrients.
2 Why do lichens adhere so well to surfaces?
Lichens adhere well to surfaces because they have developed a special adaptation to bind themselves firmly to various substrates. This ability to adhere is due to several factors:
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Rhizines: Lichens have hair-like structures called rhizines. These rhizines grow out of the underside of the lichen and penetrate into the pores or cracks of the respective surface. This creates a mechanical anchorage that gives the lichen support.
The lichen often succeeds in doing this even on PV systems. However, this can usually be observed on older systems whose surfaces have already aged due to UV light, weathering and the like. -
Chemical adhesion: The surface structure of the rhizines contains chemical compounds that enable the lichens to bond with the substrate. These chemicals can react with the surface molecules of the respective substrate and thus create a strong bond.
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Production of substances: Lichens can also produce substances that promote the growth of lichens on other surfaces. These substances can slightly change the surface properties of the substrate and improve the adhesion of the lichen.
Overall, these adaptations allow lichens to adhere firmly to a variety of surfaces, be it stones, trees, roofs or other surfaces such as PV systems and solar panels.
3 When and where do lichens grow on PV and solar systems?
Lichens sometimes grow very well on solar installations. Other system operators have no problems with lichens and their problematic removal, even after years or decades. Why is that? A whole range of factors have to come together for lichens to develop on solar installations. However, if enough of these factors are present, the lichen can grow very well and bond firmly with the substrate.
These are
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Moisture: Lichens need moisture to survive. In many regions, condensation, rain or dew on the surfaces of solar panels can provide the moisture necessary for lichen growth.
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Shade: Solar panels create shade on their underside, which can lead to increased humidity. This creates ideal conditions for the growth of lichens, especially in areas with high humidity. Some of these lichens then make it to the top of the panels, where they usually first form on the lower edge, where a small amount of water often remains, especially on panels with frames.
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Microclimate: The underside of the solar panels can provide a specific microclimate that is suitable for lichens. It may have higher humidity and less sunlight, which favors growth. Certain microclimatic influences in the vicinity of a solar installation (large sources of shade, streams, exhaust air shafts, etc.) can also promote lichen growth.
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Nutrients: Dust particles and organic substances that accumulate on the solar panels can serve as a source of nutrients for lichens. These organic materials can be carried onto the surfaces of the solar panels by wind or rain. The cultivation or processing of agricultural products containing starch in the surrounding area in particular appears to favor lichen growth.
Although lichens can grow on solar installations, their growth is not desirable as they can impair the light absorption of the solar panels. The presence of lichens can lead to a reduction in the efficiency of the solar installation as they block the light that should be absorbed by the solar cells. As long as the lichens are only partially on the panels, this effect is negligible. However, once lichens are present, they can spread rapidly. Therefore, measures are taken to remove lichens from solar panels and prevent their re-growth to ensure maximum energy efficiency of the system.
4 Why is lichen a problem on solar panels?
Lichens on solar panels can lead to various problems:
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Light blockage: lichens cover the surface of solar panels and block incoming light. As solar cells need light to generate electrical energy, the presence of lichen leads to a reduction in light absorption and therefore less energy production. This can significantly reduce the efficiency of the solar system.
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Long-term damage: Lichens can damage the surface of the solar panels, especially if they grow on them for long periods of time. Their rhizines can penetrate the surface pores and break them open, which can lead to permanent damage. This can shorten the service life of the solar panels and cause repair costs. Particularly in the case of panels with a visible frame profile, lichen can also cause the frame to bend upwards slightly in the edge area, resulting in dents. The water it contains expands when it freezes and generates an extreme force that can even bend the metal of the frame profiles.
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Aesthetic reasons: In some cases, lichens on solar installations can also be a problem for aesthetic reasons. Especially in residential areas or public facilities, people often want to see clean and well-maintained solar installations, which interferes with the growth of lichens.
For these reasons, it is important to remove lichens from solar installations and take measures to prevent their re-growth to ensure maximum efficiency and performance of the solar installation and to keep cleaning and removal of lichens within the "feasible range".
4. how to remove lichens - small spoiler: There is only one solution and it comes from Cleantecs!
The cleaning methods available on solar systems are severely limited for various reasons. These can be of a practical or ecological nature. In some cases, processes such as dry ice blasting or cleaning with hot water are hampered by economic aspects or the panel manufacturers' safety data sheets.
Even the increasingly available cleaning agents for lichen removal, some of which are approved by panel manufacturers and work perfectly well, are not a solution for tradespeople in the vast majority of cases. Why is this the case? The reason is that in almost 100% of cases, it is not possible to collect the dirt in the solar cleaning process. Even biodegradable cleaning agents - a very popular misconception - must not simply be discharged into the roof drainage system or possibly into the ground on open-air systems or seep away there.
Even if this is done again and again in practice, it must be noted: This is prohibited and can be punished.
The small-scale treatment of solar installations with pads, scrapers etc. is often a safe solution for removing lichen.
If the service provider takes a clear position here and has it confirmed in writing that no liability is assumed for micro-scratches and holograms that could be caused by this work, the service would be feasible. However, this is often not affordable! Depending on the type and size of the system, the necessary height access or cherry picker alone (solar systems are not accessible) can cause immense costs. In addition, this technology can only achieve negligible performance values per employee and hour. This often leads to horrendous costs.
5 . How can lichens be removed - small spoiler: There is only one solution and it comes from Cleantecs!
For over a month now, Cleantecs, a manufacturer that has been active in the field of solar cleaning and slat cleaning for many years, has been offering a new system.
It is a lichen remover that can be guided over the panels on the Cleantecs modular poles or on various Gardiner poles on a small trolley and uses special nozzles to break up and cut off the lichen. The nozzle operates at a moderate 120 bar and already generates immense cleaning performance, which we have also documented in the video above. In this pressure range and due to the predefined distance to the panel that can be maintained with the lichen remover, we see no risk of damage to the structure, surface and technology of the solar system.
The highly developed special nozzles show us once again what a unique position Cleantecs has in the market for cleaning technology in the area of nozzles and high-pressure gearboxes. In our opinion, this is the only professional, economical and easy-to-use solution for the safe removal of lichen.
The only better way is to prevent lichens from forming in the first place....
Here, too, we strongly recommend the use of clean water to operate the lichen cleaner and its special nozzles, although the requirement here is expressly 600 liters of clean water per hour. We will be happy to advise you on how you can achieve the required liter capacity. In regions with soft water below 10° DH and cool temperatures on the day of use (so that the cleaning liquor does not dry out), city water can also be used if necessary, as long as it is rinsed with pure water afterwards.
6 What do I have to pay attention to as a service provider when cleaning a solar system with lichen?
Basically, it is important to recognize lichen infestation before cleaning and preferably already in the offer phase and to sensitize the customer to the issue.
In this way, annoying and sometimes expensive problems for the service provider can be avoided, in which the customer also demands the removal of the lichens after the simple (successful) solar cleaning and may even be in the right here if you have not properly delimited yourselves in advance and in the quotation phase.
The removal of lichens is not always necessary / desired anyway and is in any case a more time-consuming and slower process than the actual, extensive cleaning of the system.
Accordingly, we advise you to include a small note in the quotation stating that the removal of impurities such as lichens, tree resin etc. cannot be guaranteed with the "simple solar cleaning" offered (although some lichens do simply disappear). This means that in the 2nd step or in a further offer item in advance, a supplement can be easily designed and calculated which also ensures the cleaning of the lichens in a separate course. If it works out organizationally, this should be done before the actual cleaning. There may also be cases in which cleaning with the lichen remover is completely sufficient. In this case, we strongly recommend cleaning directly and exclusively with clean water. We will be happy to advise you on how this can work with a water requirement of 600 liters per hour! We recommend the Cleanctes lichen remover described above as a tool for this. This is an extremely good solution. When calculating the work, however, please note that we have to work much more slowly here than with normal solar cleaning. We assume 20-40 square meters per hour, although this value may be lower or higher depending on the conditions on site (degree of soiling, reach, cherry picker, inclination of the roof). In addition, there may also be cases where the actual cleaning still works from the ground without a cherry picker, scaffolding, etc., but a cherry picker, scaffolding or similar may have to be used to apply the lichen remover.
This can have a major impact on the overall costs!
