Zero output is the most urgent issue. Start with the simplest causes first before escalating to electrical diagnostics.

• Check inverter — is it powered on? Look for error code on display or app
• Verify AC main breaker and DC array breaker are both in ON position
• Check for grid outage — grid-tied inverters shut down automatically during outages (anti-islanding)
• Inspect rapid shutdown device (RSD) — ensure it is activated and not tripped
• Check for extreme shading from seasonal tree growth, snow cover, or bird nests
• Verify monitoring shows same day-of-week/season as last year for weather-adjusted comparison
• If microinverters: use string-level monitoring to identify failed individual units

Gradual decline over weeks or months usually points to soiling, shading, or a failing component in one string.

• Schedule professional panel cleaning — dust accumulation causes 5–25% production loss
• Review string-level monitoring: is one string consistently underperforming vs others?
• Check for new shading sources: grown trees, new neighbor construction, satellite dishes
• Inspect for cracked panels or delamination (visible bubbling or yellowing of encapsulant)
• Test MC4 connections with thermal camera to identify resistive hot spots
• Verify inverter clipping: system may be undersized for panel array (MPPT range exceeded)
• Check bypass diodes — failed diode eliminates one-third of a panel’s cells

Inverters are rated for operation up to 40–55°C ambient temperature. Hot climates or poor ventilation cause thermal throttling.

• Relocate inverter away from direct sunlight — north-facing wall or shaded area is ideal
• Ensure minimum 6-inch clearance on all sides for air circulation
• Clean inverter cooling fins/fan intake — dust buildup greatly reduces cooling
• Replace inverter cooling fan if seized or running intermittently
• Check that ventilation louvers in inverter enclosure are not blocked by insulation or debris
• Consider adding a shade panel above outdoor-mounted inverters

Battery system issues are often configuration or BMS-related. Physical battery failure is less common in the first 5 years.

• Check BMS error codes: cell imbalance, over-temperature, or low state of health (SoH)
• Verify charge and discharge setpoints in inverter configuration match battery spec
• Test battery with calibration cycle: full charge → full discharge → full charge to reset SoC reading
• Check communication cable between inverter and battery (CAN bus or RS485 disconnection is common)
• Verify battery is within operating temperature range (most Li batteries: 0–45°C)
• For lead-acid: measure specific gravity of each cell — replace cells with reading below 1.15

Roof leaks from solar installations are rare but serious. Always use flashing, not just sealant alone, for roof penetrations.

• Identify leak source by running a hose test (one zone at a time) rather than assuming the penetration is the cause
• Replace split or cracked butyl tape on flashings — do not just apply more sealant over old failed sealant
• Check that flashing slides under the uphill shingle (correct waterfall-style install)
• Ensure no standing water can pool on flat or low-pitch sections around mounts
• If asphalt shingles are granular-depleted around penetrations, consider shingle replacement before re-sealing
• Document all penetration locations for roofer reference and warranty purposes

Monitoring outage does not necessarily mean the system stopped producing — it may just be a communication issue.

• Check home WiFi router — monitoring gateways lose connection after router password change
• Re-pair monitoring gateway to WiFi network using manufacturer app/instructions
• Power-cycle the monitoring gateway (unplug for 60 seconds)
• Verify inverter is still producing by checking LED status and display reading
• Update monitoring app — outdated app versions sometimes lose server compatibility
• Check if cloud monitoring server is down (most manufacturers have status pages)
• For cellular monitoring: check cellular data plan renewal and signal strength at install location