It was originally said that cleaning and maintenance of photovoltaic systems was not necessary. However, it has become apparent that weather and air pollution do leave their mark. The energy crisis in South Africa has seen proliferating numbers of solar panel installations in order to keep the lights on and maintain productivity in facilities. In order to use solar power as efficiently as possible and to keep the electricity yield at the highest possible level, regular professional cleaning with the correct equipment is necessary, according to Kärcher, a global leader in cleaning technology.
Cleaning and maintenance of photovoltaic systems
All types of photovoltaic systems should capture sunlight for as many hours as possible and withstand external influences. These include rain, storms, and hail, and, depending on the location, soot, pollen, dust from road traffic, leaves, needles or bird droppings.
Why should solar panels be cleaned?
Clean the panels regularly, not only because of their appearance. Contamination can reduce the electricity yield by up to 30 per cent. Thorough, professional cleaning is necessary, and this does not only apply to the surfaces of the solar collectors. Deposits build up at the junctions between the glass and the frame, which over time can lead to the formation of moss and lichen over a wide area.
Proper cleaning of the solar panels requires the correct cleaning technique due to heavy soiling. The modules are often mounted on roofs at a steep angle of 45°, so take measures to ensure operator safety.
When should you clean photovoltaic panels?
Solar systems should be cleaned using the right technology and, depending on the location, using professional service providers. Panels that are exposed to less pollution from the environment can be cleaned once a year or every two to three years. In this case, green electricity can be generated even more sustainably – a topic that will become increasingly important in the future.
The correct tools for cleaning solar panels
A professional high-pressure cleaner in combination with a brush attachment or a roller brush and a telescopic lance are among the best ways to clean solar panels efficiently and ergonomically. With the correct cleaning technique, it is possible to clean a solar panel area of up to 1500 m2 per day.
Kärcher recommend an attachment with two disc brushes that reach a working width of 800 mm. The effort required is reduced because the system neutralises the drifting movement with the help of the counter-rotating movements of the two brushes.
In addition, the large working width ensures a high area output, which reduces the amount of work required for solar cleaning. The disc brushes have ball bearings and are driven by the water from the high-pressure cleaner. Low-pressure operation with cold water and a delivery rate of 700 to 1000 l/hr is sufficient.
A nylon bristle ensures scratch-free cleaning to protect the sensitive surfaces of the solar panels during cleaning. Models with harder bristles on the outside of the plates also ensure very good cleaning results on the module frames.
It should be possible to control the amount of water comfortably via a lever on the lance while the brushes are guided in paths over the solar modules. Turning the water up a little at the beginning creates a sliding layer that makes it easier to move the brushes on the surface. A self-adjusting articulated joint to which the brush head is attached can help compensate for different working angles.
Choose the length of the telescopic lance to match the size of the system or use an infinitely extendable lance. Longer lances made of carbon or carbon composite are lighter and, therefore, more comfortable to handle.
If you value more flexibility and have to clean large façades in addition to photovoltaic systems, you are better off with a variable lance system. Pole systems that are suitable for vertical and horizontal surfaces are available and can be combined with different attachments. Use a high-pressure nozzle for spot cleaning, an attachment with disc brushes for working on horizontal PV elements or a rotating high-pressure roller brush, which is also suitable for vertical façades.
The advantage of roller brushes is that they are driven by high pressure and work their way up independently – meaning you need to be holding them with significantly less force. The roller brushes can work with water flow rates from 350 l/hr. Brushes with soft or hard bristles are available for different surfaces. It is recommended to use soft brushes for cleaning photovoltaic systems.
Use cleaning agents and a water softening system for the best results
When using cleaning agents, these should be suitable for removing stubborn, greasy soiling and mineral residues. If the water film breaks down quickly, streak-free drying without limescale stains is possible. Soaking time and rinsing, therefore, shouldn’t be needed, facilitating the cleaning process. In order to clean the photovoltaics sustainably, Kärcher recommend a cleaning agent that prevents further soiling.
Water softening system
If the water hardness range is greater than medium, Kärcher recommend a water softening system. This prevents staining despite the high lime and mineral content of the tap water. The water softener contains a resin filter with an ion exchanger that retains limescale and minerals.
The position of a system determines from where and with which tools the solar panels can best be cleaned in a way that ensures the safety of the employees. On roofs that are difficult to access, use a cherry picker. If the roof is easily accessible, work from the roof ridge or with the help of fall protection attached to the roof. The prerequisite for this is that the necessary safety hooks are located on the roof ridge. The fall protection consists of a harness around the pelvis and shoulders that is connected to a core rope. In an emergency, the harness immediately hooks on and safely catches the user. Some safety systems also include a strap fall absorber to reduce the impact in the event of a fall.