Map morning and afternoon shadows using photos or shade analysis apps. Look for new obstructions: growing trees, vent pipes, antennas, or seasonal sun paths changing impact. Compare string outputs to spot localized issues. If one panel lags after a dust event, soiling is likely. Validate with a test clean on a single module, then decide whether a full wash is justified.
Loose MC4 connectors, water ingress in junction boxes, or deteriorating insulation can quietly erode performance. Watch for uneven string current, intermittent inverter faults, or ground fault warnings. Only qualified individuals should open enclosures or test live circuits. If under warranty, follow manufacturer procedures to preserve coverage. Photographs, thermal images, and serial numbers speed resolution and confirm permanent fixes.
All modules slowly decline, but abnormal drops demand attention. Compare measured performance against nameplate and warranty curves, adjusted for temperature and irradiance. Maintain a clear timeline with cleaning events, repairs, and weather notes. If thresholds are crossed, file a polite, evidence-rich claim. Manufacturers respond best to organized data, repeatable tests, and professional diagnostics supporting a fair, durable remedy.