Dedicated section for you to find answers to the questions we are most often asked. If yours is not on the list, or if you would like to discuss it in depth, please feel free to contact us directly here, we will be happy to go into the details of your facilities & cleaning needs
There is no single answer to that question, as it depends on the exact localization of the PV structure to be cleaned. Even in desertic areas without industrial or agricultural pollution, water-based cleaning may be necessary (occasionally), for instance to clean sand that has been cemented over the PV surface by dew overnight making dry cleaning ineffective or at least less relevant than in "normal" sandy conditions.
Again, no homogeneous answer can be given, as the combination of influencing factors on the cleaning frequency can be unlimited since one has to take into account:
Most often, the financials of a PV project are based on the LCOE (Levelized Cost Of Energy) which represents the total costs of production throughout its life cycle... As the today, cases where soiling (or non-cleaning) costs are integrated are rare, although awareness of these issues is changing the approach. So, in theory, one could instead decide to integrate the costs of non-cleaning and decide to make the financial decisions that follow. But that would involve a long list of prerequisites that are not so easy to integrate financially:
Studies have demonstrated that flat PV modules are much more prone to the effects of soiling when compared directly to high angle structures. As mentioned above, other key dimensions such as the type of fouling material, wind direction, frequency of rain events, etc., must be taken into consideration when defining the cleaning procedure for a specific PV installation.
Let's take the example of your car windshield: in the absence of rain, without the mechanical contribution of water and the simultaneous action of the windshield wipers, it can quickly become clogged. More seriously, all studies done on the effects of clogging on PV production take into account "one-off" weather events such as rain, which have a positive (but limited) impact on cleaning, since it lacks the mechanical action of the brush.
Solar farms are built with an average lifetime of 20-30 years; not only will production losses be greater over time without a cleaning procedure in place, but the risk of hot spots will also be multiplied, rapidly damaging the panels, sometimes to the point of requiring complete panel replacement.
Our WetSlider dedicated to the automatic cleaning of narrow-spaced tracker solar farms uses water both for its motion and for cleaning of the modules at the same time. To accomplish both tasks, only 0.5 L of water/m² is needed: unlimited movement and clean solar panels is no longer a utopia!
Solar parks using tracking systems are often equipped with several (tens of) thousands of solar panels, to be multiplied by an average of 1.5-2.5 m2 per module... the math is both simple and eloquent when calculating the total surfaces to be cleaned. Our hydraulic movement technology ensures that no battery limits will prevent the cleaning operations from running smoothly, while also offering the possibility of having several robots working in parallel, thus increasing the efficiency of the operations. The average roof area is more limited, and although we are seeing a rapid expansion in the average size of roofs, the Rider on its lithium batteries has enough range to clean them.
Our Rider, which is primarily designed for rooftop applications, can operate at maximum inclinations of 25°/47%, which is already a high-end operational feature. However, the same robot can be equipped with a lateral guidance system that will allow operation on ground-mounted solar panels at an inclination of more than 25°.
As for our WetSlider, dedicated to the cleaning of photovoltaic systems on tracker, its design allows operations at any angle of inclination, from -55 to +55°: a real advantage because it is not necessary to stop the tracking for cleaning operations, ensuring that the gains in cleaning production are not mitigated by stopping the tracking as is often the case!