A central factor for the performance of PV cleaning is the rotational speed (rpm – “rounds per minute”), which directly affects the mechanical action. Equally important is the circumferential speed (m/s), as it describes the actual relative movement of the bristles to the module surface.
Excessive circumferential speed can accelerate bristle wear and even cause micro-damage, while insufficient speed significantly reduces cleaning effectiveness. A balanced setting is therefore crucial: lower speeds are preferable for sensitive surfaces or delicate tasks, whereas higher speeds provide more efficiency for robust surfaces.
In practice, 300 rpm for the solarROBOT compact and 400 rpm for the solarROBOT pro have proven ideal for PV cleaning robots, as they ensure both efficiency and gentle solar cleaning.
The brush diameter also has a major impact on cleaning performance. With the same rotational speed, a larger diameter increases the peripheral speed and provides better surface coverage. At the same time, however, the weight increases, and with it the energy requirement. In photovoltaic cleaning, typical brush diameters range between 150 mm and 300 mm—depending on the drive system and module configuration. In high-quality systems, a combination of high rotation and large diameter is deliberately chosen to thoroughly remove even stubborn soiling. For example, the large PV cleaning robot solarROBOT pro has a diameter of 300 mm, and even its smaller brother, compact, still has an impressive diameter of 280 mm.
The bristle material significantly determines the performance of a PV cleaning brush. Commonly used are:
They are the first choice for gentle yet thorough cleaning of PV modules.
They are used for robust cleaning tasks and heavier soiling.
The choice of bristle material should always depend on the degree of soiling, the module coating, and the environmental conditions.
Not only the material itself, but also the arrangement, thickness, and length of the bristles influence cleaning performance.
Dense vs. loose – dense increases the contact surface, loose improves dirt absorption.
Helix/Spiral shape – consistent results, good self-cleaning, prevents dirt accumulation, ideal for uneven or sloped surfaces.
Segmented – targeted dirt removal through higher point load.
Thick and long – different bristle thicknesses allow for a combination of abrasive and gentle cleaning. Homogeneous bristle fields ensure even load distribution and facilitate maintenance.
The optimal photovoltaic cleaning brush combines the appropriate brush diameter, the correct speed, the suitable bristle material, and a well-thought-out arrangement with effective water guidance. Only when all these factors work together harmoniously is efficient, gentle, and sustainable cleaning of solar modules possible.
If you are unsure, you should conduct a PV cleaning brush test before purchasing or seek direct advice from the manufacturer. When buying a cleaning robot, it is worth taking a close look at the installed brush system, as it significantly influences the cleaning results.
Would you like to learn more about the possibilities of a cleaning robot or our cleaning systems? Then please contact us; we would be happy to advise you!
The hyCLEANER editorial team brings together internal subject matter experts from various company departments – from practical application and technical development to sales and customer consulting. Together, they pursue the goal of presenting complex topics related to the cleaning of photovoltaic systems, glass surfaces, and facades in an understandable, practical, and compact way. The content is based on many years of industry experience, technical expertise, and insights from daily use in the field.
PV cleaning | Glass and facade cleaning | Cleaning robotics | Industrial cleaning
Last technically reviewed: 2026-06-17
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