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Detection and treatment of dust and dirt on photovoltaic panels

Updated: Jan 9

Dry seasons in several regions of the world are associated with large amounts of dust and dirt that come from deserts. This is correct to large sections of North America, including Mexico and the US states of California and Texas. And of course in southern Europe, Eastern Mediterranean and North Africa, which are affected by the deserts of Sahara, Egypt and Arabia. The soiling extensively covers every exposed surface including, of course, photovoltaic panels.

Photovoltaic system with soiling and after cleaning
Fig 1. Solar systems in Eastern Mediterranean: a system with soiling and a cleaned solar system (2018).

The phenomenon of dirt and dust of course occurs throughout the year, but is especially annoying in the dry season, when the amounts of dust are particularly large and there is no rain. Furthermore, the spring and summer periods in the Northern Hemisphere are characterized by a particularly high output of solar PV systems. Thus, the performance impairment is particularly noticeable. How much dust and dirt can impact the performance of a solar system? The answer is quite significant - a PV system that is not cleaned for a long period of time during the dry season drops by 10-15% in output, and even more when it is also combined with chemical or organic soiling factors such as bird droppings. Dealing with the phenomenon is simply to clean - between at least once a year (low tariff and low soiling systems) and 3-6 times a year (high tariff and/or high soiling impact systems). Systems that are washed three times a year lose on average about 3-5% of the annual output. For high-tariff and high-soiling impact PV systems, there are also automatic robotic cleaners and splash cleaning solutions, thanks to which a solar system loses only 0.5-2.0% of its maximum performance potential.


It is interesting to note that the timing of cleaning plays an important role in dealing with the problem of soiling accumulation - on one hand relying on rain for natural cleaning of a solar system is less ideal unless it is heavy rain, while on the other hand repeated daily system washing with water sprinklers can increase metal corrosion over the years and increase the degradation rate of panels (if carried out during solar hours). The common method for determining the cleaning schedule is making the washing on fixed dates - once a month, once a quarter or once every six months for those who perform manual washing and alternatively daily or once every few days for automatic and robotic washing. The disadvantage of running cleaning at predetermined times is the lack of adjustment to the amount of soiling on the system.

Accurate soiling measurement with Soltell's Sensorless technology. (2018).
Fig 2. Accurate soiling measurement with Soltell's Sensorless technology.

If there was an accurate measure of the amount of soiling - the timing of cleaning would be much more beneficial to productivity and overall cost-efficiency. Soltell's Sensorless technology accurately quantifies real-time dust and dirt levels on solar photovoltaic systems, facilitating precise scheduling of cleaning based on the specific accumulation thresholds. This happens at a precise timing that will optimize cleaning and improve usefulness, and all this without installing any additional sensor hardware on a system.


Solar solution providers - interested in advanced Sensorless technology for measuring the soiling on PV systems with no extra hardware? Fill details to receive a demo or contact us.

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