Preventive Maintenance, Cleaning and Performance Monitoring
Planned maintenance
Preventive Maintenance, Cleaning and Performance Monitoring covers keeping a system safe and productive. A preventive schedule includes visual inspection, cleaning, checking connections for discoloration or heat, torque checks, cable gland inspection, battery water topping for flooded types, and inverter filter cleaning. Thermal imaging can reveal hot connectors, cells or diodes. Record every check so trends can be compared.
Cleaning and monitoring
Clean early morning or late afternoon when modules are cool, using soft brushes, plain water and no abrasive powder. Avoid high-pressure jets near connectors and junction boxes. In dusty regions, cleaning may be needed every 1–4 weeks; after cleaning, compare output before and after. Monitor daily yield, performance ratio (PR) and string currents. A sudden drop points to a fault; a gradual drop suggests soiling, degradation or shading.
Worked example
A 5 kW array should generate about 25 kWh on a day with 5 peak sun hours. It actually produces 20 kWh. The shortfall is 5 kWh, or 20 %. Check irradiance and temperature first, then compare string currents. If one string is 15 % low, inspect that string for soiling or a failed bypass diode rather than assuming the whole array has degraded.
Traps
Do not throw cold water on hot modules; thermal shock can crack glass. Do not clean with diesel, detergent or a hard brush. Do not ignore a 10 % persistent yield loss; it may be a connector heating up.