Solar Inverter Issues

Important! Maintenance or electrical work in Australia can only be performed by a competent licensed electrician.

Solar inverters are the heart of any solar power system. They convert DC electricity from solar panels into usable AC power. Like any electrical device, they can develop faults over time. Understanding how to troubleshoot and fix common inverter issues is essential for electricians and solar installers.

This guide will cover the most frequent solar inverter problems, their causes, and how to resolve them effectively.

Safety Precautions Before Troubleshooting

Before working on any solar inverter, it’s crucial to follow these safety precautions to prevent electrical hazards:

• Turn off power: Shut down the inverter and isolate the system from both AC and DC power sources before performing any checks.
• Use proper PPE: Wear insulated gloves, safety glasses, and appropriate footwear to protect against electric shocks and arc flashes.
• Follow lockout/tagout (LOTO) procedures: Ensure the system cannot be accidentally re-energized while performing maintenance.
• Avoid working in wet conditions: Ensure that hands, tools, and the working area are dry to prevent electrical hazards.
• Verify voltage levels: Use a multimeter or a test lamp to confirm that no live voltage is present before touching any electrical components.
• Refer to manufacturer guidelines: Always consult the inverter’s manual before attempting repairs or troubleshooting.

1. No Power or Inverter Not Turning On

Causes:

• Disconnected or faulty wiring
• Tripped circuit breakers or blown fuses
• Faulty inverter or internal component failure
• Insufficient sunlight (for daytime startup issues)

Troubleshooting Steps:

• Check both the DC and AC connections for disconnected or loose wires.
• Inspect the main switchboard for tripped breakers or blown fuses and reset or replace them if necessary.
• Ensure the inverter is correctly mounted and adequately ventilated.
• Test the inverter’s input voltage with a multimeter; check panel connections if there’s no input.
• If the issue persists, refer to the manufacturer’s manual or contact technical support.

Example Manuals:

• Fronius Inverter Manual
• SMA Manuals and Guides
• Huawei Solar Support

2. Error Codes or Fault Lights

Common Causes:

• Overvoltage or undervoltage issues
• Grid connection problems
• Internal component failure
• Overheating

Troubleshooting Steps:

• Check the inverter’s display for error codes and refer to the user manual for their meaning.
• Ensure the grid voltage and frequency are within the acceptable range.
• Inspect cooling fans and ventilation to ensure the inverter is not overheating.
• Reset the inverter by turning it off and on again after a few minutes.
• If the issue persists, contact the manufacturer’s service line, a firmware update or component replacement may be needed.

Brand-Specific Issues:

• Fronius: “State 107” error often indicates high grid voltage; consult the energy provider.
• Sungrow: “Grid Fault” errors can occur due to voltage fluctuations; check wiring and settings.
• Growatt: “Error 116” relates to insulation resistance issues; verify grounding.

3. Low or No Power Output

Causes:

• Shading on solar panels
• Dirty or faulty panels
• DC cable degradation
• Inverter efficiency issues

Troubleshooting Steps:

• Inspect solar panels for dirt, debris, or shading and clean if necessary.
• Test the DC voltage at the inverter input; if it’s low, check for damaged cables or faulty panels.
• Compare actual power output to expected levels using the system’s monitoring software.
• If the inverter is underperforming, consult the manufacturer or replace it if necessary.

Brand-Specific Issues:

• SMA: “Derating” – This warning on the display indicates overheating; check cooling.
• Enphase: Microinverters may fail due to individual panel issues; inspect module connections.

Recommended Manuals:

• Enphase Microinverter Guide
• SMA Manuals and Guide

4. Frequent Inverter Shutdowns

Causes:

• High grid voltage
• Overheating
• Poor ventilation
• Loose connections

Troubleshooting Steps:

• Measure the grid voltage; consult the energy provider to adjust voltage settings if it is too high.
• Ensure the inverter is in a well-ventilated area and not exposed to direct sunlight.
• Tighten all electrical connections to prevent fluctuations.
• Restart the inverter and monitor performance.

Brand-Specific Issues:

• Sungrow: Tends to shut down due to high-temperature warnings; if so improve its ventilation.
• Goodwe: Reports “AC Freq High” shutdowns; adjust grid frequency max and min tolerance settings.

Recommended Manuals:

• Goodwe Inverter Manual
• Sungrow Technical Support

5. Wi-Fi or Monitoring System Not Working

Causes:

• Weak or lost internet connection
• Incorrect Wi-Fi settings
• Outdated firmware

Troubleshooting Steps:

• Restart the router and check if the inverter reconnects.
• Ensure the inverter is within Wi-Fi range.
• Reconfigure the network settings in the inverter’s app.
• Check and apply firmware updates when available.

Brand-Specific Issues:

• Fronius: Wi-Fi modules may need a reset or reconfiguration.
• SolarEdge: Some models require a LAN connection instead of Wi-Fi.
• Huawei: Connection stability improves with firmware updates.

Recommended Manuals:

• SolarEdge Troubleshooting
• Fronius Support

Preventive Maintenance Tips

• Perform regular inspections of wiring, connections, and components.
• Clean solar panels periodically to maintain efficiency.
• Keep the inverter in a cool, dry, and ventilated space.
• Monitor system performance through the inverter’s app or dashboard.
• Schedule annual professional inspections to ensure long-term reliability.

Conclusion

Troubleshooting solar inverter issues requires a methodical approach to identify and resolve problems efficiently. Electricians and solar technicians can ensure optimal system performance and longevity by following the above steps. Regular maintenance and monitoring can help prevent most inverter failures before they become significant problems.

For professional solar training and certifications, visit AUSINET to enhance your solar installation and troubleshooting skills.

Last reviewed date: 11/07/2025