"Cleaning solar panels is nonsense, they will get clean by themselves due to rain." Have you heard that before? But is that true, is solar panel cleaning nonsense? And when it comes to large solar parks or company roofs with hundreds or even thousands of panels? In this blog, we set out the facts. Because when it comes to efficiency and sustainability, the truth is rarely that simple.
Why this topic is important
Solar panels are designed to generate energy for a long time - often more than 25 years. For an individual with a few panels on the roof, cleaning might not seem worthwhile. But for larger solar installations on farms, distribution centres, industrial roofs or solar parks, it's all about efficiency, reliability and recouping a serious investment.
Yet managers of these large numbers of solar panels also sometimes have the idea that it is a waste of money. A misconception, practice has shown time and again.
Common reasons for not cleaning - and why they don't apply
1. "The rain will clean them up"
We hear this most often. It sounds plausible, but rainwater is not a cleaning agent. It washes away loose dust, but leaves a thin, often invisible layer of dirt, pollen, air pollution and minerals. Just like your car window: it doesn't really get clean after a downpour either.
Especially at companies in the agricultural and industrial sector - where there is more pollution in the air - we see that pollution actually builds up. Think ammonia, fine dust, soot and bird droppings: these adhere to the glass and cause structural yield losses.
2. "The panels have a self-cleaning coating"
A technical claim that is partly true: many modern solar panels have a hydrophobic layer that repels water, allowing dirt to drain more easily. But this system is not perfect and certainly not permanent.
- In high-pollution areas, pollutants still adhere despite the coating.
- Bird droppings, resin, pollen and mud are not just washed away.
- The coating wears down over the years due to UV radiation, temperature changes and contact with airborne chemicals (such as ammonia or particulate matter).
- On roofs with a low pitch, water does not wash away as well, so dirt actually accumulates on the underside of the panel.
In short: a self-cleaning coating may contribute something, but it does not prevent pollution. Certainly not in installations of hundreds or thousands of panels, where every percent counts.
3. "Cleaning costs more than it yields"
It may seem so, if you only look at the cost of cleaning. But if you do the maths, it is often exactly the opposite.
Calculation example:
An installation of 10,000 panels produces 3 million kWh annually. At 5% efficiency loss (a conservative estimate), you will lose 150,000 kWh. At an electricity price of €0.10 per kWh, that's €15,000 a year. The cost of professional cleaning is usually significantly lower - resulting in direct profit.
And that's not to mention the longer lifespan and lower failure risks.
4. "Cleaning is risky for the panels"
This only applies when the wrong methods are used. Think of high-pressure cleaners, aggressive detergents or hard brushes. Then scratches, delamination or damage to wiring can indeed occur.
Professional cleaning - as we perform it - works with osmosis water (without minerals or lime), soft brushes and specially developed equipment. Safe for your panels, effective against dirt. Just no cleaning is often riskier: dirt can lead to hot spots, microcracks and higher working temperatures.
Why cleaning does pay off
1. More yield, less loss
A clean panel generates more power. It's as simple as that. Especially with large-scale systems, this quickly makes thousands of euros a year difference. And if you use subsidies (such as SDE++), every kilowatt hour counts.
2. Data does not lie
More and more plants have monitoring. We see time and again: after cleaning, daily yields shoot up. These figures are black and white. Not a feeling, but measurable results.
3. Longer life of your installation
Persistent dirt can cause damage over years. Accumulation at the lower edge leads to uneven heating, deformation or even short circuits. A clean installation not only continues to operate more efficiently, but also retains its technical condition longer.
4. Insurance and warranty conditions
Some installers, suppliers and insurers require periodic maintenance. Those who fail to do so run the risk of malfunctions or damage claims. Preventive cleaning prevents discussions and costs.
How often is cleaning needed?
It depends on your environment and type of installation:
- Agricultural: 1-2 times a year (fertilisers, dust, ammonia)
- Industrial: 1-2 times a year (particulates, exhaust fumes)
- Solar parks: annually or more frequently (algae, mud, sand)
- Urban locations: at least once a year (pollution, bird droppings)
In doubt? Have a visual inspection or have a test surface cleaned and compare yields.
What is really sensible?
Don't be fooled by assumptions like "rain will do the job" or "that coating will do". For installations of tens or hundreds of kilowatt peaks, or entire solar parks, keeping the panels clean is not a luxury but a strategic maintenance decision.
You don't let a truck run for years without checking its wash, oil level or tyre pressure, do you? The same applies to solar power: good maintenance means better performance, less risk and higher returns.
Curious what cleaning will do for your installation?
We like to think along with you and make a competitive, transparent offer based on location, type of installation and accessibility.
Frequently asked questions on solar panel cleaning nonsense or not
No. They help somewhat, but are not a substitute for maintenance. They work mainly for light, dry soiling - not for organic dirt, bird droppings or industrial deposits. Moreover, they wear out over the years.
Bird droppings, mud, moss, fine dust, pollen and air pollution are notorious. They block sunlight, cause uneven heating and lead to hotspots - resulting in yield loss or damage.
Osmosis water contains no minerals and dries without leaving streaks. As a result, it leaves no residues that attract dirt. Combined with soft brushes, it ensures safe and thorough cleaning.
This is precisely when periodic maintenance is recommended. After all, without monitoring, you will not see the losses immediately. By cleaning at least annually, you prevent yield losses from going unnoticed for years.
It depends on the type of installation, accessibility and the number of panels. But in almost all cases, cleaning pays for itself within a few months through higher yields. Would you like a cost indication?