June 16, 2025, 10:40 am | Read time: 3 minutes
To ensure solar panels on the roof maintain full performance over the years, they must be cleaned regularly. Here’s what to consider and how effective cleaning really is.
Over the years, solar panels accumulate a lot of dirt: pollen, leaves, dust, sand, bird droppings, moss, lichen, or even Saharan dust. Systems along highways or on farms are even more affected. This reduces the performance of the solar panels. If they are installed at an angle, rain can help. It removes at least surface dirt. However, not all dirt is washed away by rain. Therefore, solar panels should be cleaned regularly.
When Cleaning Solar Panels Makes Sense
Many people are not necessarily aware that solar panels also need to be cleaned regularly–the misconception is that snow and rain will take care of the dirt. However, snow and rain can only partially assist in cleaning. If the solar panels are exposed to few environmental influences, cleaning every five years is sufficient, according to the German Solar Industry Association. Nevertheless, the system should be checked for dirt at least once a year.
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However, if the location frequently has leaves covering the modules or a lot of dirt from the road, cleaning must be done more often. Otherwise, the solar panels cannot perform at full capacity. We’re talking about losses of up to 20 percent.
If a solar panel is installed with a tilt angle of less than twelve degrees, it needs to be cleaned even more regularly. This is because there is no natural cleaning effect from rain or snow.
By the way: Solar panels should be regularly maintained by a professional. They can also determine if cleaning is necessary to maintain full performance.
Can You Clean Your Own Solar Panels?
In theory, you can handle simple cleaning tasks yourself. Removing leaves or light dirt doesn’t necessarily require a professional. However, it’s crucial to ensure that you don’t put yourself in danger while cleaning the solar panels.
It’s also important that cleaning is always done with cold water, according to the German Solar Industry Association speaking to myHOMEBOOK. Warm water can damage the modules. Ideally, you should clean the solar panels on a rainy or at least overcast spring day, it is advised.
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When to Have a Professional Clean Your Solar Panels
For many rooftops, a professional service must be hired to clean the solar panels. This can be for various reasons. One is that the system on the roof is not easily accessible, and it would be life-threatening for a layperson to work there.
Additionally, the components must be disconnected from the power before cleaning, and extreme caution is required as the modules can be damaged. Under no circumstances should high-pressure cleaners or strong cleaning agents be used.
What does it cost to have a professional clean a photovoltaic system? Prices vary greatly by region. It also depends on the system, the roof, and the provider. Generally, you pay per square meter.