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SolarEdge Error 35: AC Frequency Low Diagnosis

Troubleshoot SolarEdge Error 35 (AC Frequency Low) in residential hybrid inverter systems. Diagnose grid issues, inverter faults, and maintain system reliability.

Frequently Asked Questions

•What is the typical voltage range for a SolarEdge residential inverter?

The DC input voltage range for SolarEdge residential inverters is typically between 380V and 850V, while the AC output voltage is usually 240V split-phase.

•How do I check the firmware version on my SolarEdge inverter?

You can check the firmware version of your SolarEdge inverter using the SolarEdge SetApp on your smartphone or tablet. Connect to the inverter via Wi-Fi and navigate to the 'Status' or 'Inverter Info' section.

•What are the recommended surge protection devices for a SolarEdge system?

SolarEdge recommends using both AC and DC surge protection devices (SPDs) that meet UL 1449 or IEC 61643-11 standards. The SPD should be properly sized for the system's voltage and current ratings.

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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 synchronizes with the AC grid frequency to inject power. The inverter's control system continuously monitors the grid frequency using a Phase-Locked Loop (PLL). If the measured frequency deviates beyond the pre-defined limits for a sustained period, the inverter triggers Error 35 and disconnects to prevent damage or grid instability. AC coupling of battery energy storage system (ESS) and rapid shutdown (RSD) are functional during error state if DC sources are available.

Symptoms:

The SolarEdge hybrid inverter displays Error 35, indicating that the AC grid frequency is outside the allowable range (typically 59.3Hz - 60.5Hz in North America) as measured at the inverter's AC output terminals. This can lead to the inverter disconnecting from the grid.

Possible Causes:

Utility grid frequency fluctuations outside the inverter's operating range.
Loose or corroded AC connections at the inverter, service panel, or grid interconnection point.
Inverter internal frequency sensing circuit malfunction.
Incorrect grid profile setting within the inverter configuration.
External interference on the AC lines affecting frequency measurement.
Failure of components within the inverter's AC frequency regulation circuitry.

Solution:

1

Visually inspect all AC wiring connections from the inverter to the service panel and grid interconnection point. Tighten any loose connections and clean any corrosion. Use a torque wrench to ensure proper torque values.
2

Use a calibrated multimeter to measure the AC frequency at the inverter's output terminals. Compare this reading with the utility grid frequency using a separate frequency meter or a power quality analyzer. Note: A qualified electrician is required for this step.
3

Verify the inverter's grid profile settings. Ensure the selected profile matches the local utility grid standards (e.g., UL 1741 SA for North America). Use the SolarEdge SetApp to access and adjust these settings. Review the inverter's system manual for detailed instructions.
4

If the grid frequency is unstable or consistently outside the acceptable range, contact the local utility company to report the issue. Provide them with the measured frequency data and any error logs from the inverter.
5

If the inverter is suspected to be faulty, perform a thorough diagnostic test using the SolarEdge monitoring portal or SetApp. Check for any other error codes or abnormal readings. Contact SolarEdge technical support for further assistance.
6

Check for external interference. If possible, disconnect non-essential electrical loads within the home to see if that improves frequency stability.
7

As a last resort, if the inverter is under warranty, contact SolarEdge for repair or replacement options. Do not attempt to repair the inverter yourself.

Safety Warning:

This diagnosis involves working with AC and DC high voltage electrical systems. Only qualified electricians with proper personal protective equipment (PPE) should perform these procedures. Always disconnect the AC and DC power sources before working on the inverter or any associated wiring. Follow NEC rapid shutdown requirements to de-energize the PV system before maintenance. Adhere to all local electrical codes and safety regulations.

Prevention:

• Schedule regular system maintenance with a qualified electrician, including AC connection inspections.
• Periodically review the inverter's performance data in the SolarEdge monitoring portal to identify any potential issues early on.
• Keep the inverter's firmware updated to the latest version to ensure optimal performance and bug fixes.
• Ensure proper ventilation around the inverter to prevent overheating, which can affect electronic components.

Expert Tip:

Use the SolarEdge SetApp to access the inverter's service menu (requires installer access). Check the real-time grid frequency reading and compare it to the internal frequency reference. A significant difference indicates a potential issue with the inverter's frequency sensing circuit. Also, review the inverter's event log for any recurring frequency-related alarms.