Professional solar panel cleaning in French-speaking Switzerland
Switzerland is experiencing a tremendous boom in solar energy. With the Energy Strategy 2050 and federal and cantonal incentives, the number of photovoltaic and thermal installations continues to grow on Swiss rooftops. By the end of 2025, the Confederation had more than 200,000 solar installations spread across the entire country, with a total capacity exceeding 7 GW. But installing solar panels is not enough: to ensure optimal output, regular maintenance is essential.
At SOS Nettoyage, we are the specialists in solar panel cleaning in French-speaking Switzerland. Our trained teams use professional techniques that are gentle on your equipment to maximise energy production from your installation and protect your investment.
Why do solar panels need cleaning?
Loss of output due to soiling
Solar panels are permanently exposed to the outdoor elements. Over time, various types of dirt accumulate on their glass surface:
- Dust and fine particles: carried by the wind, they form a film that reduces light transmission
- Pollen: particularly abundant in spring in Switzerland, it creates a very opaque yellowish film
- Bird droppings: not only opaque, they are also acidic and can damage the anti-reflective coating
- Dead leaves and plant debris: they can partially cover cells and create shaded areas
- Moss and lichen: on shaded or north-facing installations
- Air pollution: soot, combustion residues, microparticles
- Limescale deposits: left by the evaporation of rainwater or irrigation water
Scientific studies are unanimous: a dirty solar panel can lose between 15 and 25% of its output, or even more in extreme cases (concentrated bird droppings, moss build-up). On an average residential installation of 10 kWp producing around 10,000 kWh per year, this loss represents between 1,500 and 2,500 kWh lost, or a shortfall of 300 to 500 CHF per year at the current feed-in tariff.
The “hot spot” effect: a real risk
When a photovoltaic cell is partially obscured by dirt (typically a bird dropping or a stuck leaf), it no longer produces electricity but continues to absorb energy from neighbouring cells. This phenomenon, called the hot spot effect, causes localised overheating that can:
- Reduce the lifespan of the affected cells
- Irreversibly damage the photovoltaic module
- In extreme cases, cause a fire
Regular cleaning by SOS Nettoyage eliminates these risks and preserves the integrity of your installation.
Rain is not enough
Contrary to popular belief, rain is not enough to effectively clean solar panels. Rainwater may wash away the lightest dust, but it:
- Leaves limescale marks as it evaporates
- Does not remove dried bird droppings
- Does not dislodge embedded pollen
- Is ineffective against moss and lichen
- Can even worsen soiling by redistributing the dirt
Only professional cleaning with demineralised water and suitable tools guarantees a perfectly clean, streak-free surface.
Our solar panel cleaning techniques
Demineralised water: the key to a perfect clean
SOS Nettoyage uses demineralised water (or reverse osmosis water) for cleaning your solar panels. This water, purified by reverse osmosis, is completely free of minerals (limestone, magnesium, iron). Its advantages are considerable:
- No streaks after drying, unlike tap water
- Superior cleaning power: demineralised water acts like a dirt magnet
- No need for chemicals: pure water is enough to dissolve and lift dirt
- Total respect for the anti-reflective coating on panels, which is often fragile
Rotating brushes on telescopic poles
Our technicians use professional rotating brushes mounted on telescopic poles that can reach up to 12 metres in height. These brushes have several essential features:
- Soft nylon bristles that do not damage the glass surface or anti-reflective coating
- Gentle, even rotation that lifts dirt without applying excessive pressure
- Demineralised water fed directly through the pole for continuous rinsing
- Ergonomic design allowing work from the ground in most configurations
Ground-level cleaning: maximum safety
In the majority of cases, our technicians clean your solar panels from the ground using telescopic poles. This method offers major advantages:
- Safety: no climbing onto the roof, no risk of falling
- No pressure on the panels: no risk of cracking cells due to a person’s weight
- Speed of intervention: no need to set up and take down scaffolding
- Reduced cost: less labour and equipment required
For flat roof installations, large solar farms or complex configurations, we can work directly on the roof with safety equipment compliant with SUVA standards (harnesses, lifelines, non-slip footwear).
Special cases: moss and lichen
When moss or lichen have developed on the aluminium frames or between panels, specific treatment is required. SOS Nettoyage applies a biodegradable anti-moss treatment that eliminates the growth and prevents its return for several months. This treatment is safe for the panels, the roof and the environment.
When and how often should you clean your solar panels?
Recommended frequency
The optimal cleaning frequency depends on several factors:
| Situation | Recommended frequency |
|---|---|
| Standard residential installation | 1 to 2 times per year |
| Near deciduous trees | 2 times per year (spring + autumn) |
| Agricultural area (dust, pollen) | 2 to 3 times per year |
| Near a busy road | 2 times per year |
| Urban / industrial area | 1 to 2 times per year |
| Low tilt angle (< 15°) | 2 to 3 times per year |
| Steep tilt angle (> 30°) | 1 time per year |
| Significant bird presence | 2 to 3 times per year |
The ideal seasons
The best times to clean your solar panels in Switzerland are:
- Spring (March-April): after winter, panels are often covered with residues left by snow, rain and winter pollution. A clean at the start of spring allows you to maximise production during the sunniest months (May to September)
- Autumn (September-October): to remove pollen, summer residues and the first fallen leaves before winter arrives
SOS Nettoyage ideally recommends a clean in spring, just before the peak production period, to optimise your return on investment.
Monitoring to decide the right time
If your installation is equipped with a monitoring system (such as SolarEdge, Enphase or Fronius), you can track the output of your panels and detect an abnormal drop in performance that could indicate soiling. A production drop of more than 10% compared to the expected value (taking weather into account) is a clear signal that cleaning is needed.
Return on investment from cleaning
ROI calculation for a residential installation
Let us take the example of a typical residential photovoltaic installation in French-speaking Switzerland:
- Power: 10 kWp (approximately 25 panels)
- Theoretical annual production: 10,000 kWh
- Average feed-in tariff: 0.15 CHF/kWh (self-consumption + grid injection)
- Output loss without cleaning: 20% on average
- Lost production: 2,000 kWh = 300 CHF/year
- Annual cleaning cost: approximately 150 – 300 CHF
The cleaning pays for itself within the first year and often generates a net benefit of 50 to 150 CHF per year, not counting the preservation of the panels’ lifespan.
For commercial and industrial installations
For large installations (warehouse rooftops, ground-mounted solar farms, agricultural buildings), the financial stakes are even higher. A 100 kWp installation with a 20% output loss loses approximately 3,000 CHF per year. Professional cleaning, with economies of scale, typically costs 1,000 to 2,000 CHF for this size of installation, representing a very favourable ROI.
Solar panel cleaning prices in Switzerland
Indicative rates
| Service | Indicative price |
|---|---|
| Cleaning per panel (residential) | 3 – 8 CHF / panel |
| Flat rate residential installation (15-30 panels) | 200 – 600 CHF |
| Flat rate medium installation (30-60 panels) | 500 – 1,200 CHF |
| Large commercial installation (> 100 panels) | On request |
| Anti-moss treatment (supplement) | 50 – 150 CHF |
| Visual inspection + report | Included |
Prices vary depending on:
- Accessibility of the installation (height, roof pitch, obstacles)
- Number of panels to be cleaned
- Level of soiling (an initial clean after several years takes longer)
- Geographic location in French-speaking Switzerland
Request your free, no-obligation quote from SOS Nettoyage. We assess your installation and offer you a precise rate, with no surprises.
Safety: an absolute priority
Risks involved in solar panel cleaning
Solar panel cleaning presents specific risks that justify calling in a professional:
- Risk of falling: panels are on the roof, often several metres above ground. In Switzerland, falls from roofs are a major cause of domestic accidents
- Electrical risk: photovoltaic panels produce electricity as soon as they are exposed to light. A damaged panel or a poorly insulated cable can cause electrocution
- Risk of damage to panels: too much pressure, an unsuitable product or an abrasive tool can scratch the glass, damage the anti-reflective coating or crack the cells
- Risk to the roof: walking on a roof without precautions can damage tiles, metal sheeting or waterproofing
SOS Nettoyage safety measures
At SOS Nettoyage, safety is our absolute priority:
- SUVA training for all our technicians in working at height
- Personal protective equipment (PPE) compliant with Swiss standards
- Systematic risk assessment before every intervention
- Ground-level cleaning preferred in all possible cases
- Professional liability insurance covering any potential damage
- Strict prohibition on using high-pressure cleaners on solar panels
Why not use a high-pressure cleaner?
Using a high-pressure cleaner (Karcher or similar) is strongly advised against for solar panels. The water pressure can:
- Damage the waterproof seals between the frame and the glass
- Cause micro-cracks in the tempered glass
- Deteriorate the anti-reflective coating that optimises light capture
- Shift the fixings and compromise the stability of the installation
SOS Nettoyage exclusively uses low-pressure water with rotating brushes, the method recommended by all solar panel manufacturers.
Photovoltaic panels vs thermal panels
Cleaning photovoltaic panels
Photovoltaic panels convert sunlight into electricity. Their surface is made of tempered glass with an anti-reflective coating. Cleaning must be particularly gentle to preserve this coating. SOS Nettoyage adapts its techniques accordingly.
Cleaning thermal panels (solar thermal)
Solar thermal panels heat water using solar radiation. They often have a different glass surface (borosilicate glass) and may include vacuum tubes. Their cleaning requires particular attention to connection areas and fragile tubes. Our technicians are trained in the specific requirements of each type of panel.
Solar panel cleaning and the environment
Solar panel cleaning by SOS Nettoyage is an environmentally responsible approach:
- Demineralised water only: no chemicals flow into the environment
- Limited water consumption: approximately 5 litres per panel, far less than watering a garden
- Optimised green energy production: clean panels produce more renewable electricity
- Extended panel lifespan: less electronic waste in the long term
- Biodegradable anti-moss products when treatment is needed
By maintaining your solar panels, you maximise your contribution to Switzerland’s energy transition while optimising your return on investment.
Service areas in French-speaking Switzerland
SOS Nettoyage provides solar panel cleaning throughout French-speaking Switzerland:
- Geneva and surrounds: residential and commercial
- Lake Geneva region: Lausanne, Montreux, Vevey, Nyon, Morges
- Valais: Sion, Martigny, Sierre and resorts
- Neuchatel and Jura: Neuchatel, La Chaux-de-Fonds, Delemont
- Fribourg: Fribourg, Bulle, Morat
For large commercial installations, we also operate beyond French-speaking Switzerland. Contact us to find out more.
Legal framework and subsidies in Switzerland
In Switzerland, the maintenance of solar installations is encouraged by public authorities as part of the Energy Strategy 2050. Several French-speaking cantons offer support programmes for solar energy that may include maintenance recommendations. Furthermore, the one-off payment (PRU) disbursed by Pronovo for small photovoltaic installations is conditional on the proper functioning of the installation, which implies regular maintenance.
Solar installation owners also have an obligation to maintain their equipment in good condition under the general grid connection terms of their local electricity distributor (SIG in Geneva, Romande Energie in the canton of Vaud, Groupe E in Fribourg, etc.). An abnormally low output due to soiling may be considered a maintenance failure.
Tips to keep your panels clean for longer
- Cut back branches overhanging your panels to limit leaf and dropping deposits
- Install anti-pigeon devices if birds frequently nest on your roof
- Monitor your system to quickly detect any drop in output
- Schedule an annual clean in spring with SOS Nettoyage to start the peak season in optimal condition
- Never attempt to clean your panels yourself if your roof is difficult to access
Request your free quote
Want to optimise the output of your solar installation? SOS Nettoyage is the specialist in solar panel cleaning in French-speaking Switzerland. Contact us for your free, no-obligation quote. Our technicians assess your installation and offer you a rate tailored to your needs.
A clean panel is a productive panel. Trust SOS Nettoyage to get the most out of your solar investment.
Frequently asked questions about solar panel cleaning
Do solar panels really need to be cleaned?
Yes, solar panel cleaning is essential for maintaining optimal output. Contrary to popular belief, rain is not enough to remove all dirt. Bird droppings, pollen, pollution and limescale deposits accumulate and can reduce energy production by 15 to 25%. Studies conducted in conditions similar to those in French-speaking Switzerland confirm that regular cleaning significantly improves electricity production.
How often should solar panels be cleaned?
For a standard residential installation in French-speaking Switzerland, cleaning 1 to 2 times per year is recommended. The frequency can be increased to 2 to 3 times per year if your panels are located near trees, in an agricultural area, near a busy road or if your roof has a low pitch (less than 15°). SOS Nettoyage will advise you on the ideal frequency during the initial assessment.
How much does solar panel cleaning cost in Switzerland?
The price of solar panel cleaning ranges from 3 to 8 CHF per panel for a residential installation. As a flat rate, expect between 200 and 600 CHF for a typical installation of 15 to 30 panels. Large commercial installations benefit from economies of scale and receive a customised quote. Request your free, no-obligation quote from SOS Nettoyage to find out the exact rate for your installation.
Can I clean my solar panels myself?
Technically, it is possible to clean your panels yourself if the installation is easily accessible (flat roof, secure access). However, we strongly advise against it for several reasons: risk of falling, risk of damaging the panels with an unsuitable product or tool, and electrical risk. Moreover, without demineralised water, cleaning with tap water will leave limescale marks that reduce output. Using SOS Nettoyage guarantees optimal results and total safety.
Do you use chemicals to clean the panels?
No, SOS Nettoyage exclusively uses demineralised water (purified by reverse osmosis) for solar panel cleaning. This pure water has superior cleaning power compared to tap water and leaves no marks after drying. No chemicals are needed or used. The only case where a supplementary product may be applied is the biodegradable anti-moss treatment on aluminium frames, if necessary.
Can cleaning damage my solar panels?
Not when carried out by a professional like SOS Nettoyage. We use soft-bristled rotating brushes specially designed for delicate glass surfaces, combined with low-pressure demineralised water. We never use high-pressure cleaners, abrasive sponges or harsh chemicals. Our method complies with the recommendations of all major solar panel manufacturers.
What is the best season to clean solar panels in Switzerland?
Spring (March-April) is the ideal time. Cleaning at this time of year removes the dirt accumulated during winter and allows you to start the period of strong sunshine (May to September) with perfectly clean panels. A second clean in autumn (September-October) is recommended if your installation is particularly exposed to pollen, fallen leaves or bird droppings.
Do you also work on flat roof installations?
Yes, SOS Nettoyage works on all types of installations: pitched roofs, flat roofs, facades, ground-mounted or on special structures (solar carports, pergolas). Flat roof installations often require more frequent cleaning because the reduced tilt angle prevents partial self-cleaning by rain. Our technicians access the roof with regulatory safety equipment (SUVA standards) and clean each panel with care.