One of the most commonly asked questions regarding module maintenance, is how to clean the panels. Dirty modules not only affect the overall aesthetic of your array, they can be less efficient as dust and debris block rays from reaching solar cells. There are companies that provide cleaning services for both residential and commercial solar arrays. If you worked with an installation company, they may offer free cleaning services, check with your installer to see if they offer cleaning or can recommend a company that does.

However, home and business owners can clean their modules without taking on additional costs. We recommend checking manufacturer installation and users guides for the best methods of cleaning modules. For this overview, we have looked specifically at Canadian Solar’s installation guide, which has a section dedicated to cleaning and maintenance. Most modules will follow similar procedures, however, checking specific requirements will assist in avoiding any damage or injury during cleaning.

Pre-Inspection and Safety

• Before cleaning, inspect modules thoroughly for any cracks, damage, or loose connections. Damaged solar panels represent electrical shock hazards.
• Disconnect the circuit before you begin cleaning.
• Disconnect the array from other active components (such as the inverter or combiner boxes).
• Wear protective clothing and gear.

Handling

• Use proper cleaning solutions and cleaning equipment.
  • Do not use degreasers
  • Do not use cleaning corrosive solutions containing acid, alkali, acetone, or industrial alcohol.
• Do not submerge the modules partially or completely, in water or any cleaning solution.
• Do not use abrasive or electric cleaners on the panels.
• Avoid using the rotating brush cleaning method, this can lead to the formation of micro-cracks.
• Do not scrape or scrub dirt when the modules are dry.

Cleaning Tips

• Noticeable dirt must be rubbed away by gentle cleaning tools such as a soft cloth, sponge or bush with soft bristles. Ensure that brushes are approved for cleaning glass.
• Avoid cleaning modules during the hottest hours of the day to avoid thermal stress on the panel.
• Water with low mineral content, near neutral pH levels, water pressure should be a maximum of 4MPa (40bar)

How do you know when/if your solar panels need to be cleaned? A visual inspection is the first method, if you see noticeable dirt, pollen, bird droppings or other debris on the panels, you should give them a clean. Some monitoring systems will alert you when you need to clean your modules, by informing you of any obstructions or loss in efficiency.

In order to clean your modules, you will need a hose and maybe some soap, whether or not you need soap largely depends on the amount of buildup on your panels. Do not put soap directly on the panels, put some soap into a bucket and use as needed. Laundry detergents and stronger chemicals will affect your panels negatively, dish soap is oftentimes the best and safest cleaning agent to use. To start, wash down your modules with water, and if there is still noticeable dirt use the soapy water at your discretion. Ensure any brushes or cloths you use to wash away any particularly troublesome dirt is approved for glass surfaces. Washing your panels is a lot like washing your car at home.

Solar panel cleaning is not too complicated, however safety precautions and proper cleaning solutions and tools are essential. Rain, snow and the tilt of your panels will keep the modules largely clean and you should not have to wash your modules too often. Recommendations range from washing your panels once a year to once every five years. The frequency of how often they should be washed is largely up to the end user. Efficiency loss typically sits at under 5% even on the dirtiest of modules, however, any efficiency loss is not ideal, and being aware of the state of your modules assists in consistent energy production.