For the photovoltaic panel to look (and produce) like the first day, it is essential to clean its surface from time to time. Proper maintenance and cleaning can increase the efficiency of the panel and its life span.
As time goes by, and due to bad weather, dust in suspension in the environment, etc, solar panels accumulate a layer of dirt on their surface. This dirt considerably reduces the efficiency of the panel, in terms of the electricity it generates, and can even create so-called hot spots, which negatively affect the life of the panel. For this reason, the cleaning of photovoltaic panels is essential.
This cleaning should be done periodically, but does not have to be complicated: it can be done with everyday materials without too much effort. You can remove the dirt from the surface of the panel as if it were the glass of a window, with warm water and a drop of soap or dishwasher and rubbing with a cotton cloth that does not release fibers, or a polyester brush with thick bristles, so as not to scratch the panel. Care should be taken not to use any soap or abrasive cleaning product to avoid damaging the surfaces. It is recommended to carry out this cleaning with a periodicity appropriate to the air quality and the climate of the area, although in many cases, rain is usually enough to remove the dirt.
However, the main difficulty in carrying out this cleaning yourself lies in whether the installation is on a rooftop, in which case the problem is difficult access and dangerousness. A recommendable and safe option is to take advantage of the periodic maintenance of the photovoltaic installation by experts to also give the panels a professional cleaning.
The picture shows a clear example of the difference between a dirty panel, in operation for months, (right) and a clean panel just placed (left). This is a 50 kW installation in a pig farm.