There are two methods for cleaning solar PV modules:
- Dry Cleaning
- Wet Cleaning
In this method of cleaning, a brush, sponge or a cloth is used to clean the surface of the modules without using water or any other liquid. The brush or cloth must not be rubbed vigorously as it may can result in scratches on the surface of the PV module. Dry cleaning may not be suitable for tough strains such as bird-droppings, dead insects, tar etc.
In this method of cleaning, water is used to eliminate dirt from the surface of the solar PV module. It is done by using a soft cloth, brush, detergent(non-abrasive) and clean water.
Few recommendations for wet-cleaning of solar modules:
- Cleaning time: The recommended time for cleaning modules is during low light conditions when production is lowest. The best time to clean modules is from dusk to dawn when the plant is not in operation and risk of electrical shock hazard is minimum.
- Quality of water: The water must be free from any suspended particles that could damage the module surface. De-ionized water is preferable for cleaning the modules. If de-ionized water is not available, tapwater or rainwater can also be used
- Use of cleaning agent: A mild, non-abrasive, non-caustic detergent with water may be used. De-greasers, Acid or alkali detergent should not be used
- Removing stubborn marks: To remove stubborn dirt such as birds dropping, dead insects, tar etc., use a soft sponge, micro-fiber cloth or non-abrasive brush. Rinse the module immediately with water
- Drying: Modules should be dried after rinsing using a chamois or rubber wiper with a plastic frame on an extension pole. Wipe the module surface from top to bottom to remove any residual water from the module
- Water pressure: Water pressure should not exceed 35 bar at the nozzle. Use of high pressure hoses for cleaning may exert excess pressure and damage the modules
- Water temperature: Temperature of water used for cleaning should be same as ambient temperature at the time of cleaning.
- Do not sprinkle water on the back surface of the module