- Wear rubber sole shoes with good traction to prevent slips and falls.
- Never walk on the modules. Use non-conductive extended reach broom and hose handles to reach modules.
- A lift may be needed to access the array. Follow aerial lift safety procedures, including wearing a harness if required.
Checklist before Washing
- Walk the site to confirm that there are no broken modules (shattered glass). Never spray broken modules with water. Perform a safety evaluation of the site looking for safety hazards such as trip hazards or areas that will become excessively slippery when wet.
- Plan for water runoff. If the site has a storm water prevention plan in place, determine how the used water will be collected and disposed of. If harmful chemicals are not used during the cleaning process, drain guards can be used to filter out sediments.
- Be aware of trip hazards introduced by having hoses spread throughout the property, cone off area if needed.
- Determine whether the module cover glass is too hot and will be damaged by coming into contact with cool water. Depending on the local climate and time of year, it may be best to limit washing activities to the morning or evening hours.
- Identify the water source to be used. Ideally, there will be a source of water near the array. If not, it may be necessary to bring in water from an outside source, which will involve a tank or water truck.
- Determine the best method of getting water to the modules. Typically, a ¾-inch garden hose is used to connect to a spigot near the array.
- Set up hoses and tools.
- If required, block or install drain guards for filtration or water capture purposes.
- Take a baseline production reading of the system, noting both kilowatt-hour (kWh) output of each of the inverters and weather conditions including temperature and irradiance.
How to Wash if required
- De-ionized water is preferred to prevent spotting and calcium buildup.
- Normal water pressure of 50 to 70 pounds per square inch is recommended; do not use high pressure washers.
- If high pressure washers are necessary, hold the pressure source far enough away from the modules to prevent damage. As a rule of thumb, if the stream is too strong to comfortably hold one’s hand in, it is too much pressure for the modules.
- Spray the modules with water.
- Use a soft-bristled brush to get stubborn dirt off.
- If needed, use a non-damaging soap.
- Use extensions with tools to be able to reach extended distances.
- If needed, squeegee modules dry.
After Washing Modules
- After the system returns to steady-state temperature (i.e., there is no remaining impact from the cooling effect of wash water), take another production reading of the system, noting both kWh output of each of the inverters and weather conditions including temperature and irradiance.
- Clean up tools.
- Remove any drain guards or blocks.
- Record the washing in the maintenance log.
- Compare production of the clean system to the previous production values.
*Note – Above steps are taken from the Solar ABC guide. The guide can be further looked upon for the other equipment used in the solar photovoltaic system.
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