ᐅ Should you regularly clean your solar panels yourself?

Hello!
Is it true that solar panels need to be cleaned regularly because they lose efficiency otherwise? If so, what is the best way to do this? Should you clean them yourself or hire professional help? And how often is this necessary?

Hello Nordlicht

I can only give you a general rule of thumb regarding photovoltaic systems. However, I assume something similar applies to solar thermal systems.
As a rule, you can expect the system to clean itself during rain if you have a (roof) pitch of at least 30° and live in a village or town.
Problems may arise with lower angles or if there is unusually high pollution in your area.
For example, in agricultural regions, a dry, dusty field near the system can cause significant soiling. Or emissions from older industrial plants, coal power stations, or similar.
If none of this applies to you, then the effort and cost of cleaning will likely be much higher than the minimal loss in energy yield caused by dirt.

Another option is if you live in a bungalow and can clean the system with your garden hose. In that case, you will have hardly any cost or effort…

Best regards
Micha

Yes, solar panels lose efficiency if they are not cleaned. We always have them professionally cleaned twice a year. The costs are still reasonable. For 50m² (540 sq ft), you can expect to budget around 70 to 100 euros.

That's exactly what I wanted to ask. What type of solar systems are being referred to? Solar thermal collectors or photovoltaic panels?
With solar thermal systems, there is also a distinction between flat-plate collectors and evacuated tube collectors.
In general, the surfaces of the collectors are designed to repel dirt. However, cleaning them occasionally definitely doesn't hurt! Ideally, clean them once in spring and again in autumn, or have them cleaned. It also depends on how accessible they are.

Hello, I am new to the forum and we are also planning to build a house; we are currently still waiting for quotes. I would like to install a solar / photovoltaic system on the roof and have questions about cleaning. I have already done some research, and opinions vary widely, but almost everyone agrees that cleaning improves efficiency. Some friends of ours have applied a nano-coating to their system, and I looked into it as well, but I haven’t found a clear answer about whether it is beneficial and which product to use.

Hello

I find it interesting that many people put a lot of effort into cleaning their system and invest heavily to increase yield (I hadn’t even heard of nano-coatings until now...), but when it comes to building or having a technically safe system installed, safety is considered too expensive. A good example is that many customers find even a simple surge protection too costly...
Or they prefer to buy the cheapest modules from China, since quality modules (which don’t only come from Germany) are supposedly much too expensive...

@Harry: The absolute amount of 70–100 euros doesn’t say much by itself... How large is the system?

If I assume an average residential system of about 4 kWp, that would be 25 euros per kWp per year. At the current feed-in tariff of around 19 cents, the system would need to generate roughly 130 kWh/kWp more output after cleaning for the cleaning to pay off at all.
With an average irradiation in the Ruhr area of 850 kWh/kWp per year, that equals about a 15% increase. Even in southern Germany, with 1100 kWh/kWp per year, that’s still around 12%.

I know systems located in the middle of fields that get very dirty, where the loss in yield is only around 5–6%...

My simple advice: It’s better to invest a bit more money in a well-designed system and find a good solar installer who delivers a technically and professionally sound installation. Then, under normal conditions, you usually don’t have to worry about dirt accumulation...

Best regards
Micha