Goodwe Error Code 120 – Meaning, Causes & Solution -... | solardiagnostics.org

Technical Background:

Error 120 indicates a failure in the insulation resistance test, which is a critical safety feature of the inverter designed to detect ground faults. The inverter continuously monitors the insulation resistance (RISO) between the array and ground. If the insulation resistance falls below a predetermined threshold, typically due to moisture, physical damage, or degradation of the insulation material, the inverter triggers this fault to prevent potential electrical hazards. Ground fault detection is essential to avoid shock hazards and ensure the safe operation of the solar energy system.

Symptoms:

Users experiencing Goodwe error 120 will notice the inverter's LED indicator may flash red or display an error message on the monitoring app. Additionally, there may be a significant drop in energy production, with the inverter failing to operate normally or shutting down entirely.

Possible Causes:

Insulation resistance failure in the solar array due to moisture ingress or physical damage.
Ground fault within the inverter or string connections, indicating a breach in insulation.
Poor connections at the junction box or MC4 connectors leading to intermittent faults.
Overvoltage conditions due to excessive sunlight or inappropriate system configuration.
Internal inverter fault or malfunction of the isolation monitoring circuit.

Solution:

1

Disconnect the inverter from the grid and isolate the solar array using the MC4 disconnect tool.
2

Use a megohmmeter to perform an insulation resistance test on the solar array, ensuring readings are above the minimum threshold (typically 1 MΩ).
3

Inspect all connections at the junction box and MC4 connectors for signs of corrosion or damage; repair or replace as necessary.
4

Check for any moisture ingress in the array or junction box that could contribute to insulation failure; ensure proper sealing.
5

Reconnect the system and monitor the inverter status via the monitoring app for any reoccurrence of error 120.
6

If the error persists, consult the inverter manual for specific diagnostic procedures or contact Goodwe technical support for further assistance.

Safety Warning:

Always ensure that a licensed electrician or certified solar installer performs any troubleshooting or repairs to maintain compliance with safety regulations and the National Electrical Code (NEC).

Prevention:

To avoid future occurrences of error 120, ensure regular maintenance checks on the solar array and inverter, including visual inspections for moisture, physical damage, and tight connections. Additionally, consider using weatherproof junction boxes and connectors to minimize exposure to environmental factors.

Frequently Asked Questions

•What does Goodwe error code 120 indicate?

Error code 120 indicates a failure in the isolation test, which is crucial for safety. It suggests that the inverter has detected a potential fault in the electrical isolation.

•How can I troubleshoot isolation test failures?

To troubleshoot, check the wiring and connections for any faults or damage. Ensure that the inverter is properly grounded and that all components are functioning correctly.

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention:

Frequently Asked Questions

•What does Goodwe error code 120 indicate?

•How can I troubleshoot isolation test failures?

Related questions

Technical Background:

Symptoms:

Possible Causes:

Solution:

Safety Warning:

Prevention: