Solar panels are installed outside where they can get maximum sunlight. Since they are outside, they are prone to outside dust, dirt, leaves, bird droppings etc. All these parameters reduce the output of the solar panels and in long run also reduces solar panel efficiency. With dust, dirt etc the output of solar panels falls by 30% to 40%. Regular cleaning of Solar panel is one of the main obstacles or the only drawback in this zero-maintenance system.

Solar installations come in different shapes and sizes, so the following steps are meant as a guide only and the installation should be assessed for safety and access before commencing cleaning. If in doubt at any time when cleaning the panels, stop and obtain professional advice.

When working at heights, use fall and personal protection measures throughout the cleaning process.

Remember: Never at any point stand on, walk on, lean on or apply pressure to the panels as this can cause both visible and non-visible damage to the panel.

Various types of soft foams, non-woven fabrics, brooms, soft sponges and soft brushes are permitted.

The nylon brushes which have the wire diameters from 0.06-0.1 mm are recommended to use.

Glass cleaner, alcohol and methyl alcohol are only allowed to use in case of the water cannot clean properly.

The use of pressure or steam cleaners and high pressure hoses, knives, blades and metallic sponges is not permitted on panels and will invalidate the warranty.

Do not use cleaning agents which contains hydrochloric acid, D-Limonene, ammonia, sodium hydroxide, benzene, nitrite diluents, acids or alkalis products.

Panel cleaning should be carried out before reaching working temperature i.e., early morning or night times and must only be cleaned with water at ambient temperature to avoid thermal shock.

Cleaning of panels should only be carried out when the panels are cool to avoid thermal shock. During the day, ambient temperature rises and the panels heat up as they produce energy, usually to around 20°C above the surrounding conditions. Applying cool, cold or lukewarm water to hot panels can cause components (e.g., glass) to shrink rapidly, potentially causing cracks and breakages. Inversely, the application of hot or boiling water to cold panels may cause rapid expansion of components and similar breakage. Therefore, only water at ambient temperature should be used.

Normally, the accumulated dust can be washed with water, but in some instances some maintenance is recommended to clean the surface of the glass with water and a soft cloth or sponge to remove layer of dirt. A mild non-abrasive detergent may be applied to remove persistent dirt from both the sides of module.

A standard flexible garden hose with domestic water pressure may be used to apply as much water to the panel or array as necessary, allowing the water to run down the entire surface.

Also, water spraying systems or equipment whose Pressure do not exceed 35 BAR (500 PSI) at Nozzle output can be used.

Make sure the panels are not drilled, mechanically altered or heavily loaded with equipment to perform Automatic / Semi-Automatic Cleaning.

If the panels require more cleaning effort to remove stubborn marks, use a soft sponge, microfiber cloth or a soft and non-abrasive brush and lightly wipe over the affected area. This may be mounted on an extension pole for an extended reach. Treatment in this manner should remove any loose soiling from the panel glass.

If marks still remain on the panels, a mild biological and biodegradable washing-up liquid may be used on the panels. The panel must be immediately rinsed with plenty of water. IPA (Isopropyl Alcohol) with a concentration of less than 10% may be be used. Acid or Alkali detergent must not be used.

Fresh water (TDS < 1500 mg/L) may be used to clean the modules. If needed, a mild, non-abrasive,

non-caustic detergent with a final fresh water and detergent solution mix between 6.5 < pH < 7.5 at 25°C may be used.

Water must be free of floating oil or other immiscible liquids, floating debris, excessive turbidity, and objectionable odors.

When using hard water, RO water provides the best results. When RO water is not available, tap water with low mineral content (total hardness <75 mg/L) or deionized water may be used. Calcium should not exceed: 75 mg/ml.

When using hard water (75 mg/L < total hardness < 180 mg/L), the water must be squeegeed off to prevent scale buildup.

Chlorides should not exceed 250 mg/ml and water conductivity should be < 250 mS/cm

The best way to dry panels is to leave them to dry naturally in the air.

If for some reason this is not possible, they can alternatively be wiped dry with a chamois or by use of a rubber squeegee with a plastic frame on an extension pole. Wipe the panel surface from the top downwards to remove any residual water from the panel glass, but pay attention that any leftover grains of dirt or sand do not scratch the surface of the panel.

When using hard water (75 mg/L < total hardness < 180 mg/L), the water must be squeegeed off to prevent scale buildup.

Wet Cleaning

The wet spray cleaning techniques for uncoated modules above may be used for ARC modules.

Wet contact cleaning (squeegees, sponges, cloths, etc.), which includes any simultaneous combination of water and scrubbing/wiping is prohibited for ARC modules.

Excessively soiled spots on modules (i.e. bird droppings) may be spot-cleaned with soft cloth or mop and water, if necessary, for localized cleaning only.

Use of hard water (75 mg/L < total hardness < 180 mg/L) is prohibited on ARC Modules.

 Dry Cleaning

Generally Dry Cleaning is risky for ARC Modules.

 NOTE: Spinning or Rotating Brushes should not be used on ARC Modules.