Maintenance: Preserving Safety and Yield
Maintenance covers planned inspections, condition monitoring, diagnostics, and corrective work over the system life. Exam items ask you to interpret trends, select tests, and choose safe corrective actions. IEC 62446-2 provides the maintenance framework; manufacturer instructions and NFPA 70E govern safe work.
Program rules
- Start from a baseline: commissioning IV curves, string Voc/Isc, insulation-resistance values, and PR. Trend against irradiance and temperature, not calendar dates.
- Scheduled visual inspection looks for cracked glass, backsheet damage, corrosion, rodent damage, loose connectors, and degraded signage.
- Thermal imaging under load finds hotspots, open bypass diodes, and high-resistance terminations. Confirm with IV curve tracing and string current measurements.
- Electrical checks include string current balance, Voc, insulation resistance, ground continuity, and torque verification after thermal cycling.
- Inverter maintenance: clean filters, inspect fans, download error logs, and verify firmware settings. For storage, check state of charge, thermal management, and ventilation.
- Record every finding in a work order with location, irradiance, temperature, meter, and corrective action.
Worked example
One string in a parallel group reads 7.2 A while sibling strings read 8.0 A at the same irradiance. The 10% deficit is beyond typical measurement error. Check for soiling or shading first, then connector heating, a blown fuse, or an open bypass diode. If Voc is normal but Isc is low, suspect a module substring or connection; a thermal image can localize it before module replacement.
Traps
Spraying cold water on hot modules; assuming low current always means a failed module; resetting an inverter without reading its fault log; cleaning without checking manufacturer restrictions; skipping torque checks after seasonal thermal cycling.