Studies proof efficiency losses of solar power plants due to soiling. The data ranges from three to six percent in Europe and up to 35 % in the Middle East of efficiency to be lost because of less light coming through to the solar cells.
SOLARBRUSH is the global pioneer in robots for solar power plants, as the inventor, Ridha Azaiz, developed the first robot back in 1997 (see first tv presentation from 1999 below). Other systems have been developed upon this idea and add to the available solutions.
MANUAL CLEANING: There are different approaches of cleaning solar cells. One is manual cleaning with a telescope brush that reaches high altitude. Sometimes this is combined with a lift on a car and a water supply. When choosing this option, consider costs for utilities, labour and water. The results using this option can be very good.
- SPRINKLERS: Another approach is an installation where sprinklers water the plant occasionally to wash the dirt off the field. The water is either lost or recycled with a catching tank below the field. Sometimes the water comes with pressure for better results. Costs for installation and water apply, but less for labour as the process is automated. The video seems to show good achievements.
- INSTALLATIONS: There have been presentations with installed devices, e.g. brushes, sprinklers, covers and sponges, that are moved over solar modules to get rid of deposits. These usually require separate chains and drives around the solar field. While the solutions are automated, the technology is exposed to the weather. This makes the effort for maintenance questionable as errors might be hard to locate. Maintenance costs apply. These are static solutions that might be hard to relocate. Interrupted PV fields might therefore require multiple investments, e.g. on each array.
- SPRINKLER CARS: There have been converted fire engine cars or utility cars that have sprinkler arms that drive through the solar fields. Consider labour and investment for the car when choosing this option.
- NANO COATINGS: Less light coming through to the cells, abrasion by deposits in the wind and low temperature resistance make it hard for nano coatings to become available.
EXPLANATION FOR EFFICIENCY LOSSES ON PV FIELDS
A single cell in a solar panel produces about half a volt. To get a usable output, the cells are switched together in a row that adds the voltage up to e.g. 12. The cell with deposits produces less current than the surrounding ones. The shadow caused by the deposits let it act as a resistor, scaling the total output according to its very own down and causing heat. To prevent that cell from damage, the manufacturers of the modules install diodes into each string. This means that if only one cell within a string is covered, the whole string will detach, leading to disproportional losses. A diode consumes more power than a single cell would produce, so the manufactures compromise in installing only one diode into a string. The same problem again applies to several solar panels switched together, becoming a so called row or array.