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SolarEdge Hybrid Inverter Error 18xC0 Arc Fault Reset Required

Troubleshoot SolarEdge Error 18xC0: Arc Fault Interruption. Expert guide to reset, diagnose causes, and prevent future arc fault events in residential systems.

Frequently Asked Questions

•What are the NEC requirements for rapid shutdown systems in residential PV installations?

NEC 690.12 mandates rapid shutdown for PV systems on buildings. This requires the ability to de-energize PV conductors within a specified distance (typically 1 foot) of the array or inside the building within a short timeframe (e.g., 30 seconds) of initiating rapid shutdown.

•How do I test the functionality of the rapid shutdown system on my SolarEdge inverter?

The SolarEdge inverter has a built-in self-test function for the rapid shutdown system. Consult the installation manual for specific instructions on how to initiate the self-test and interpret the results. A successful test confirms proper operation of the rapid shutdown functionality.

•What is the recommended torque specification for DC connectors in SolarEdge PV systems?

Refer to the SolarEdge installation manual or the connector manufacturer's datasheet for the correct torque specification. Using the wrong torque can lead to loose connections, overheating, and potential arc faults.

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Marcus leads the technical research department at Storage Faults. Together with a team of systems analysts, he specializes in translating complex solar storage error codes into actionable diagnostic steps for the US market.

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Technical Background:

The SolarEdge hybrid inverter incorporates an Arc Fault Circuit Interrupter (AFCI) to detect and mitigate dangerous arc faults in the DC wiring of the PV system. The AFCI monitors the DC current for irregular patterns and high-frequency noise indicative of arcing. Upon detection, the inverter triggers a rapid shutdown and displays error 18xC0. Resetting the AFCI requires manual intervention and investigation to determine the cause of the arc fault.

Symptoms:

Inverter displays error code 18xC0, indicating an Arc Fault Interruption (AFI) event. The inverter shuts down AC output and may disconnect from the grid. The SolarEdge monitoring portal or app will also report the arc fault condition.

Possible Causes:

Loose DC connections: Improperly torqued or corroded DC connectors in the PV array or at the inverter terminals.
Damaged PV module wiring: Insulation degradation due to UV exposure, rodent damage, or physical stress leading to short circuits.
Water ingress: Moisture penetration into combiner boxes or module junction boxes creating conductive paths for arcing.
Improper grounding: Inadequate or missing grounding connections creating voltage potential differences.
Component failure: Degradation of DC optimizers or inverter AFCI circuitry.
External Electromagnetic Interference (EMI): Strong EMI can sometimes trigger false arc fault detections.

Solution:

1

*Safety First**: Ensure DC disconnect switch is in the OFF position to isolate the PV array. Verify rapid shutdown is activated according to NEC 690.12 requirements.
2

*Visual inspection**: Conduct a thorough visual inspection of all DC wiring, connectors, and PV modules for signs of damage, corrosion, or water ingress.
3

*String Testing**: Using a multimeter, measure the open-circuit voltage (Voc) and short-circuit current (Isc) of each PV string. Compare readings to manufacturer specifications and look for significant deviations.
4

*Insulation Resistance Testing**: Perform insulation resistance testing (Megger test) on DC conductors to identify compromised insulation. Follow manufacturer’s recommendations for test voltage and duration.
5

*Connector inspection**: Disconnect and inspect all DC connectors for proper seating, corrosion, and damage. Retorque connections to manufacturer specifications.
6

*AFCI Reset**: After addressing potential causes, attempt to reset the AFCI via the inverter's user interface or monitoring portal. Consult the SolarEdge system manual for specific reset procedures.
7

*Monitoring**: After resetting the AFCI, closely monitor the system for recurrence of the error. Use a clamp meter to monitor DC current in each string for unusual fluctuations.

Safety Warning:

High DC voltage is present in PV systems. Arc flash hazards exist. Only qualified electricians with proper PPE and training should perform diagnostic and repair work. Always de-energize the system and verify absence of voltage before working on any components. Strictly adhere to NEC Article 690 requirements.

Prevention:

• **Regular inspections**: Perform annual visual inspections of the PV system, including wiring, connectors, and modules.
• **Torque Verification**: Periodically verify the torque of all DC connectors and terminals.
• **Rodent Control**: Implement rodent control measures to prevent damage to wiring insulation.
• **Firmware Updates**: Ensure the inverter firmware is up to date to benefit from the latest AFCI algorithms and false-triggering mitigations.
• **Grounding Verification**: Verify grounding connections are intact and properly bonded.

Expert Tip:

SolarEdge inverters maintain an event log accessible through the monitoring portal or installer toolkit. Analyze the event log for historical arc fault events and any correlated data (e.g., time of day, environmental conditions) that may provide clues to the root cause.