Solar Panel Cleaning Tip Sheet

While cleaning solar panels is no rocket science and can be equated with regular washing of your car. There are certain things that need to be remembered to guarantee the elongated service life and efficiency of the system. Wrong cleaning practices, bad quality water, and use of inappropriate cleaning agents may damage modules and other array components and lower system performance as well. It is also essential to train the cleaning personnel on proper cleaning methods and the use of appropriate cleaning tools.

Safety of personnel:

• Solar modules are connected in series and it generates upto 800V DC. Cracks in modules or damaged cable or joints in a string are extremely dangerous for cleaning person particularly when the modules are wet. Even during low level of sunlight the array will generate lethal voltage and current. Therefore, it is important to inspect modules thoroughly for cracks, damage, and loose connections before cleaning. Cleaning personnel shall wear appropriate electrically insulating Personal Protective Equipment (PPE) during cleaning.

Cleaning time:

• The recommended time for cleaning modules is during low light conditions when production is lowest. However, when sun shines during the day, the panels also get heated up and cleaning solar panels with cold water in evening may result in thermal shock for panel which can permanently damage them. Hence, the best time to clean Solar Panels is early mornings, when the plant is not in operation, risk of electrical shock hazard is minimum and also temperature of solar panels is not high.

Quality of water:

• De-ionized water should be used to clean the modules. If de-ionized water is not available, rainwater or tap water can be used. Tap water must be of low mineral content with total hardness less than 75ppm.  Water must be free from grit and physical contaminants that could damage the panel surface.

Use of cleaning agent:

• A mild, non-abrasive, non-caustic detergent with deionized water may be used. Abrasive cleaners, Acid or alkali detergent must not be used.
• Don’t use metal objects or harsh abrasive products for removing caked on materials – scratching the glass on a solar panel can affect its performance as scratches will cast shadows.

Removing stubborn marks:

• To remove stubborn dirt such as birds dropping, dead insects, tar etc., use a soft sponge, micro-fiber cloth. Rinse the module immediately with plenty of water.

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. Cleaning should be carried out when the modules are cool to avoid thermal shock which can potentially cause cracks on the modules.