Clean the solar system yourself regularly?

Hello! Is it true that solar systems need to be cleaned regularly, otherwise they lose performance? If yes, what is the best way to proceed? Clean them yourself or get external help? And how often would that be necessary?

Hello Nordlicht

I can only give you a rule of thumb regarding photovoltaic systems. But I suppose a similar assumption can be made for solar thermal systems. Generally, you can assume that the system cleans itself when it rains if you have a (roof) slope of at least 30° and live in a village or a town. Problems could occur with lower slope angles or if there is unusually high pollution in your area. For example, in agricultural areas, a dry, dusty field near the system can lead to extreme contamination. Or emissions from older industrial facilities / coal power plants or the like. If none of this applies to you, then the effort / cost of cleaning would likely be much higher than the minimal loss in yield due to contamination.

An alternative is: you live in a bungalow and can clean the system with your garden hose. Then you have hardly any costs or effort...

Best regards Micha

Yes, solar systems lose performance if they are not cleaned. We always have this done professionally twice a year. The costs are still manageable. For 50sqm, you should budget around 70 to 100 euros.

That's exactly what I wanted to ask now. What kind of solar systems are meant? Solar thermal collectors or photovoltaics? In solar thermal, one also differentiates between flat-plate collectors and tube collectors. But basically, the surfaces of the collectors are designed to repel dirt. However, cleaning them every now and then definitely doesn't hurt! It's best to clean once in the spring and then once in the fall, or have them cleaned. It also depends a lot on accessibility.

Hello, I am new here in the forum and we are also planning to build, currently still waiting for offers. I would also like to install a solar/photovoltaic system on the roof and am wondering about cleaning. I have already read up on this and opinions vary greatly, but almost everyone comes to the conclusion that cleaning increases efficiency again. Friends of ours have had a nano-sealing applied to their system and I have also looked into it, but have not received an answer on whether it is good and what to use.

Hello

I find it always interesting that many people worry about cleaning the system, put a lot of effort into increasing the yield (Nanosealing is something I haven't even heard of yet...) and spend a lot of money on it, but when it comes to building / having built a technically safe system, safety is considered too expensive. Best example: many customers find a simple protection against surges already too expensive...
Or they prefer to take the cheapest Chinese modules because quality modules (which are not only available from Germany) are way too expensive...

@Harry: The absolute value of 70-100 euros unfortunately doesn't say much... How big is the system?

If I now assume an average system for a single-family house of about 4 kWp, that's 25 euros per kWp per year. With the current feed-in tariff of about 19 cents, the system would have to produce about 130 kWh/kWp more yield after cleaning for the cleaning to pay off at all.
With an average irradiation in the Ruhr area of 850 kWh/kWpa, that is an increase of about 15%. Even in southern Germany with 1100 kWh/kWpa, that is still around 12%.

I know systems that lie in the middle of fields and are therefore extremely dirty - the loss in yield here is about 5-6%...

My tip is very simple: better invest a little more money in a decent system and find a good solar technician who installs a technically and craft-wise good system, then normally you don't have to worry about dirt...

Regards
Micha