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Hoymiles Error Codes

Expert reference guide covering all Hoymiles microinverter diagnostic codes with comprehensive troubleshooting procedures and professional repair guidance

Quickly identify problems with your Hoymiles solar system and learn the correct response procedures

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Hoymiles Microinverter Models

Hoymiles produces an extensive lineup of premium microinverter systems for residential and commercial solar installations. The HM series represents standard microinverter technology with high efficiency, while HMS series models provide enhanced features and performance. HMT series offers three-phase solutions for larger installations. These diagnostic codes are applicable to the majority of Hoymiles microinverter systems sold in the United States. Error indicators typically manifest as status messages in the monitoring app, LED status indicators on microinverters, and system alerts in the monitoring portal.

How to Read Error Codes

• Check monitoring app for system alerts and status messages
• Review microinverter LED status indicators
• Check data logger status and connection
• Review system status in monitoring portal
• Consult Hoymiles documentation for your specific model

Hoymiles Product Series

• HM Series - Standard high-efficiency microinverters
• HMS Series - Enhanced microinverters with advanced features
• HMT Series - Three-phase microinverters for larger systems
• Data Logger - System monitoring and communication
• Monitoring App - Mobile and web-based monitoring platform

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Understanding Diagnostic Codes

Hoymiles microinverter systems incorporate sophisticated diagnostic capabilities that automatically detect operational issues. When a problem is identified, the system communicates through status messages in the monitoring app, LED indicators on microinverters, and system alerts in the monitoring portal. This intelligent diagnostic framework enables rapid problem identification and helps determine the appropriate response. All Hoymiles microinverter series (HM, HMS, HMT) utilize continuous performance monitoring with real-time error detection. Status messages may appear as informational (requiring no action), warnings (requiring attention), or errors (requiring immediate action). Always reference your specific system's documentation for precise message definitions.

Grid Connection Errors

Problems with AC grid voltage, frequency, and connection.

Code	Meaning	Possible Causes	Solutions
Grid Overvoltage	Grid voltage exceeds maximum limit - System shutdown for safety	•Utility grid voltage too high •Grid voltage fluctuations •Transformer tap settings •Grid instability •Voltage regulation issue	Do not attempt to override safety shutdown Check utility grid voltage with multimeter Contact utility company to report voltage issues Wait for grid voltage to return to normal range System will automatically reconnect when voltage stabilizes Contact certified installer if voltage issues persist
Grid Undervoltage	Grid voltage below minimum limit - System shutdown for safety	•Utility grid voltage too low •Grid voltage fluctuations •Transformer issues •Grid instability •Voltage drop in distribution	Do not attempt to override safety shutdown Check utility grid voltage with multimeter Contact utility company to report voltage issues Wait for grid voltage to return to normal range System will automatically reconnect when voltage stabilizes Contact certified installer if voltage issues persist
Grid Frequency Out of Range	Grid frequency deviation from allowable range - System shutdown	•Grid frequency too high •Grid frequency too low •Grid instability •Frequency fluctuations •Grid synchronization issue	Check grid frequency (should be 50Hz or 60Hz depending on region) Verify frequency is within allowable limits Microinverter will automatically attempt to reconnect when frequency returns to normal Wait for grid frequency to stabilize Contact utility company if frequency is consistently out of range Contact installer if problem persists
Grid Disconnected	System has lost connection to utility grid	•Grid power outage •Main breaker tripped •Utility disconnect •Grid failure •Anti-islanding protection	Verify grid power is actually lost Check main breaker for system This is normal safety behavior during grid outage Wait for grid power to be restored System will automatically reconnect when grid is restored If grid is normal, contact installer to check grid connection

DC Voltage and Isolation Errors

Problems with DC input voltage and electrical isolation.

Code	Meaning	Possible Causes	Solutions
DC Overvoltage	DC input voltage exceeds maximum limit	•Too many modules per microinverter •Module voltage exceeds maximum •Cold weather voltage rise •Incorrect module configuration •Module mismatch	Check module voltage with multimeter Verify module specifications match microinverter requirements Account for cold weather voltage rise in calculations Verify module voltage is within microinverter specifications Contact certified installer to verify module configuration
DC Undervoltage	DC input voltage below minimum operating threshold	•Too few modules •Shading on panel •Faulty module •DC wiring losses •Module configuration error	Check module voltage with multimeter Verify minimum module voltage requirements Inspect panel for shading Check for faulty module Verify DC wiring connections Review module configuration Contact certified installer if voltage remains low
Isolation Fault	Isolation error detected between PV module and ground	•Damaged module insulation •Water ingress in junction box •Damaged DC wiring insulation •Ground fault in module •Faulty microinverter isolation monitoring	Immediately shut down the system Do not attempt to restart until fault is resolved Inspect module connections and junction box Check DC wiring for damage or water ingress Test isolation resistance with megohmmeter Contact certified Hoymiles installer immediately This is a serious safety condition requiring professional diagnosis

Microinverter Communication Errors

Problems with microinverter communication and data transmission.

Code	Meaning	Possible Causes	Solutions
Microinverter Not Reporting	Microinverter is not sending data to data logger - Communication lost	•Microinverter power loss •Communication wire break •Data logger communication issue •Network connectivity problem •Microinverter failure	Check microinverter LED status (should indicate normal operation) Verify microinverter is receiving DC power from solar panel Inspect communication wire connections Check data logger device status Verify network connection between microinverter and data logger Restart data logger device if multiple microinverters are not reporting Contact Hoymiles support if issue persists after troubleshooting
Some Microinverters Not Reporting	Multiple microinverters not sending data - Partial communication failure	•Communication wire break in string •Data logger communication issue •Network segment failure •Power loss to multiple microinverters	Identify which microinverters are not reporting in monitoring app Check if non-reporting units are on same communication string Inspect communication wire for breaks or damage Verify all microinverters are receiving DC power Check data logger device status and network connection Restart data logger device to refresh communication Contact certified installer if multiple units fail simultaneously
Data Logger Offline	Data logger device is not communicating with monitoring portal	•Data logger device offline •Internet connection failure •Network configuration issue •Data logger device failure •Power loss to data logger	Check data logger device power and LED status Verify data logger has internet connection (check network cable or WiFi) Restart data logger device by unplugging for 30 seconds Check router and network configuration Verify data logger can reach Hoymiles servers Check monitoring portal for system status Contact Hoymiles support if data logger cannot establish connection

Production and Performance Errors

Problems with energy production and system performance.

Code	Meaning	Possible Causes	Solutions
Production Problem	Energy production below threshold or serious hardware problem detected	•Low solar irradiance •Shading on panel •Microinverter failure •Panel failure •DC wiring issue •Production below expected threshold	Check weather conditions and solar irradiance levels Inspect panel for shading from trees, buildings, or debris Review production data in monitoring app for patterns Check individual microinverter status in Devices tab Verify DC connections at panel and microinverter Inspect panel for physical damage or soiling Compare current production to historical averages Contact certified installer if production is consistently low
Zero Production	No energy production from microinverter - Complete production failure	•Grid outage •All microinverters offline •Main breaker tripped •System shutdown •DC disconnect open	Check grid power status Check main AC breaker for system Inspect data logger device status Verify system is not in maintenance mode Check for utility grid issues or outages Review monitoring app for system alerts Contact certified installer if grid is normal but production is zero
Low Production	Energy production significantly below expected levels	•Shading on panel •Dirty or soiled panel •Panel degradation •Microinverter derating •DC wiring losses •Mismatched modules	Clean solar panel to remove dirt, dust, or debris Check for shading throughout the day Inspect panel for physical damage or hot spots Verify microinverter is operating (check monitoring app) Compare production to expected values for current conditions Check DC wiring for loose connections or damage Review panel specifications and microinverter compatibility Contact certified installer for production analysis

Temperature and Overheating Errors

Problems with microinverter temperature and thermal protection.

Code	Meaning	Possible Causes	Solutions
Overtemperature	Microinverter temperature exceeds maximum limit	•Insufficient ventilation •Direct sunlight on microinverter •High ambient temperature •Blocked air vents •Faulty cooling system	Improve ventilation around microinverter Ensure microinverter is not in direct sunlight Check that air vents are not blocked Verify adequate clearance around microinverter Allow microinverter to cool down before restart Contact installer if temperature remains high after improving ventilation
Temperature Sensor Error	Temperature sensor fault or communication error	•Faulty temperature sensor •Sensor wiring issue •Internal sensor failure •Communication error	Check temperature sensor connections Verify sensor is functioning Contact Hoymiles support for sensor diagnostics May require microinverter service or replacement

Internal Microinverter Errors

Problems with microinverter internal systems and hardware.

Code	Meaning	Possible Causes	Solutions
Internal Microinverter Error	Internal microinverter fault or hardware error	•Internal microinverter fault •Control board issue •Hardware failure •Component malfunction	Attempt microinverter restart by cycling DC power If error persists, contact Hoymiles support Do not repeatedly restart if error continues Note error details and contact certified installer May require microinverter replacement or repair
Power Stage Error	Microinverter power stage fault	•Power stage failure •DC/AC conversion issue •Hardware malfunction •Component failure	Contact Hoymiles support immediately This requires professional diagnosis Microinverter may need repair or replacement Do not attempt to repair yourself

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Critical Safety Notice

Do not attempt DIY repairs on your Hoymiles solar system. The majority of diagnostic codes relate to high-voltage DC and AC electrical systems, battery storage, grid connection safety mechanisms, or critical communication components. Specific codes requiring immediate professional intervention include: Isolation Fault, Power Stage Error, and any internal microinverter errors. Upon encountering these codes, immediately shut down the system if safe to do so and contact a certified Hoymiles installer without delay.

Professional service is mandatory—contact a licensed solar installer or reach out to Hoymiles technical support for expert assistance.

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Maintenance Guidelines

Scheduled Service Requirements

✓Professional inspection and service annually by certified Hoymiles installer
✓Monthly visual inspection of solar panels for damage or soiling
✓Clean panels quarterly or as needed based on local conditions
✓Monitor system performance daily through monitoring app
✓Check data logger status and internet connection monthly
✓Verify all microinverters are reporting in monitoring app

Proactive Maintenance Strategies

✓Keep panels clean to maximize energy production
✓Trim trees and vegetation to prevent shading
✓Inspect DC wiring and connections for damage or corrosion
✓Monitor production trends for early problem detection
✓Keep monitoring app updated for latest features
✓Review system alerts and notifications promptly

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Frequently Asked Questions

How do I check if my microinverters are working?

Check microinverter status in the monitoring app. Each microinverter should show normal operation status. Verify microinverters are receiving DC power from solar panels and are communicating with the data logger. Review production data to ensure all microinverters are generating power. Check microinverter LED indicators if accessible.

What should I do if my microinverter is not reporting?

If your microinverter is not reporting, check microinverter LED status, verify the microinverter is receiving DC power from the solar panel, inspect communication wire connections, check data logger device status, verify network connection, and restart data logger if needed. Contact Hoymiles support if the issue persists after troubleshooting.

What does "Isolation Fault" mean?

Isolation Fault indicates an isolation error detected between the PV module and ground. Immediately shut down the system and do not attempt to restart until the fault is resolved. Inspect module connections and junction box, check DC wiring for damage or water ingress, and test isolation resistance. This is a serious safety condition requiring professional diagnosis. Contact a certified Hoymiles installer immediately.

What should I do if my data logger is offline?

If your data logger is offline, check data logger device power and LED status, verify data logger has internet connection, restart data logger device by unplugging for 30 seconds, check router and network settings, and verify data logger can reach Hoymiles servers. Contact Hoymiles support if the data logger cannot establish connection.

Can I repair my Hoymiles system myself?

High-voltage DC and AC electrical work must exclusively be performed by licensed professionals to ensure safety compliance. Homeowners can safely perform basic tasks like cleaning panels and monitoring the app, but all technical repairs require certified Hoymiles installers. Unauthorized work on electrical systems poses extreme danger and violates building codes.

What does "Production Problem" status mean?

Production Problem status appears when energy production falls below a threshold or a serious hardware problem is detected. Check weather conditions, inspect panel for shading, review production data patterns, check individual microinverter status, verify DC connections, and inspect panel for physical damage. Compare current production to historical averages and contact a certified installer if production is consistently low.

What should I do if I see "Grid Frequency Out of Range"?

Grid Frequency Out of Range indicates that the grid frequency is outside allowable limits. Check grid frequency (should be 50Hz or 60Hz depending on region), verify frequency is within allowable limits, wait for grid frequency to stabilize, and contact the utility company if frequency is consistently out of range. The microinverter will automatically attempt to reconnect when frequency returns to normal.

How often should I clean my solar panels?

Solar panels should be cleaned quarterly or as needed based on local conditions. Panels in dusty areas or areas with heavy pollen may need more frequent cleaning. Keep panels clean to maximize energy production. Inspect panels monthly for damage or excessive soiling that may require immediate cleaning.

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Summary

Proper interpretation of diagnostic codes is essential for effective Hoymiles solar system troubleshooting. This comprehensive reference enables quick problem identification and guides appropriate response actions. Hoymiles systems utilize status messages in the monitoring app, LED indicators on microinverters, and system alerts in the monitoring portal to indicate specific sensor and system malfunctions. HM, HMS, and HMT series microinverters provide diagnostic information through the monitoring app and monitoring systems for convenient diagnosis.

⚠️Complex diagnostic situations, especially those involving high-voltage DC and AC electrical systems, grid connection safety, and microinverter communication, require immediate professional evaluation. Critical codes demanding urgent response include: Isolation Fault, Power Stage Error, and any internal microinverter errors. These indicators represent serious safety hazards requiring certified Hoymiles installer response. Adherence to scheduled maintenance protocols and immediate attention to diagnostic codes extends equipment service life and minimizes long-term operational costs. Note that some status messages may vary by system configuration—always consult your specific system's documentation for precise interpretations.