SOP for PV Module Cleaning

Cleaning of Solar PV Modules is a very important O&M practice to keep the module efficiency up and ensure high output from the plant, here is the SOP for PV Module cleaning:

1. Safety Precautions: Before starting any cleaning activity, ensure to take necessary safety precautions to avoid any hazards. Wear protective equipment, such as gloves and safety glasses.
2. Identify the cleaning schedule: The cleaning schedule can vary based on the site location, weather conditions, and the level of soiling. Develop a cleaning schedule based on the site-specific needs and environmental factors.
3. Water quality: The quality of water is crucial when cleaning solar modules. High mineral content water may cause mineral deposits on the glass surface, reducing the module's performance. Water must be free from grit and physical contaminants that could damage the panel surface. Use deionized, or reverse osmosis and natural pH water to prevent mineral deposits. If RO is not available, rainwater or tap water with low mineral content and a total hardness that is less than 75mg/L may be used. As per various research the TDS should not be greater than 30mg/L.
4. Cleaning solution/agents: Dilute a non-abrasive cleaning solution in water according to the manufacturer's instructions. The cleaning solution should be specifically designed for solar modules and should not contain any harsh chemicals.
5. Equipment Preparation: Before cleaning the modules, ensure that all the cleaning equipment, including brushes, sponges, and squeegees, are clean and free of dirt, debris, and other contaminants. 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.
6. Cleaning Time: The recommended time for cleaning modules is?during low light conditions?when generation is lowest. However, when sun shines during the day, the temperature of the PV panel rises and cleaning solar panels with cold water in evening may result in thermal shock/crack for panel which can permanently damage them. Hence, the best time to clean Solar Panels is early morning, when the plant is not in operation, risk of electrical shock hazard is minimum and also temperature of solar panels is not high. i.e. the temperature difference of cleaning water and the panel is less.
7. 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.
8. Module Cleaning: Start cleaning from the top row and work downwards. Use a soft-bristled brush or sponge to remove loose dirt, debris, or bird droppings. Wet the surface of the modules with water and then apply the cleaning solution using a soft-bristled brush or sponge. Allow the solution to soak for a few minutes, then scrub the surface lightly. Finally, rinse the modules with water.
9. Drying the modules: After rinsing the modules, use a squeegee or a lint-free cloth to remove excess water from the surface. Let the modules air dry completely before reconnecting them.
10. Inspection: Once the modules are dry, visually inspect them for any damages, cracks, or scratches. Repair or replace any damaged modules as needed.
11. Documentation: Maintain a record of the cleaning schedule, the cleaning solution used, and any damages observed during the cleaning process.

By following this SOP, you can effectively maintain and clean your solar modules, thus improving their performance and extending their lifespan.