top tips for solar PV module cleaning

Do you know how much dirty solar modules reduce energy yield and performance? Read this article to find out Greensolver top tips for cleaning solar PV modules.

Issue 

Photovoltaic (PV) modules, especially in dry and dusty areas, can lose a significant amount of energy yield and performance if they aren’t cleaned regularly enough. On-site issues, which are usually overlooked, such as bird droppings, deposition of dusts and water stains, can also significantly reduce solar panel efficiency. In Europe, there is between 1%-8% efficiency reduction due to module soiling. 

Prevention 

To prevent dust-based and other soiling power losses, PV systems require frequent cleaning. The frequency of such cleaning depends on the geographical location, PV integration scheme, and scale of the PV power plant. 

Geographical location of solar plants, such as desert, grassy, plain or mountainous regions and height of the installed system from the ground can all impact the level and regularity of module cleaning. Weather conditions, such as humidity and wind speed, can also affect the regularity in which modules need to be cleaned. These all impact adhesion of dust particles to the surface of PV modules. 

PV Module cleaning options 

In order to decide which PV module cleaning option is right for your assets, Greensolver recommend evaluating the best method and conditions. This takes into consideration the risk of damage to the modules that may occur during cleaning activities, as well as potential risk of electric shocks.  

The method used will depend on many factors, such as types of modules, installation, distance between arrays and water availability. Methods most commonly used are: manual, machine or robot cleaning.  

Greensolver recommendations 

Once we’ve identified any potential risks and have established the cleaning method right for your assets, based on all the factors mentioned above, it’s time to start cleaning! 

The recommended time to clean PV modules is from dusk to dawn, when production is not affected and the risk of electrical shock is minimised. Greensolver have a number of recommendations before this final step can begin: 

  1. For Uncoated Modules Wet Cleaning : 
  • Fresh water 
  • If needed, a mild, non-abrasive, non-caustic detergent with a final fresh water and detergent solution  
  • Water must be free of floating oil or other immiscible liquids, floating debris, excessive turbidity 
  • Do not use cleaning solutions containing hydrochloric acid, D-Limonene, ammonia, or sodium hydroxide 
  • Water pressure must not exceed 35 bar  
  • Do not apply water that is more than 20°C warmer or colder than module surface temperature. 

      2. For Anti-Reflective Coated (ARC) Modules 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 localised cleaning only. 
  • Use of hard water is prohibited on ARC Modules. 

Next steps…

It is important to calculate the performance of the modules before and after the cleaning, but also to follow up this KPI over time to evaluate how long the cleaning is efficient for. If you require advice and support on top tips for cleaning solar PV modules, please contact us.

In addition to module cleaning, we are able to provide many technical asset management services in order to increase energy output of your assets. Find out more about our comprehensive scope of operations services.

Written by Alberto Ruiz Santos, Asset Manager.

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