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SolarEdge•Unknown

Analysis by Marcus & Team

SolarEdge Inverter DC Injection High Error

Diagnose and resolve SolarEdge DC Injection High errors in residential hybrid inverters. Causes, solutions, prevention, and safety tips.

Frequently Asked Questions

•What is the typical lifespan of the filter capacitors inside a SolarEdge inverter?

The lifespan of filter capacitors can vary, but typically ranges from 5 to 10 years, depending on operating temperature and load conditions.

•How do I check for DC leakage from the PV array?

Use an insulation resistance tester (megohmmeter) to measure the insulation resistance between the PV array conductors and ground. Refer to the inverter's manual for specified testing procedures.

•What NEC code sections are relevant to DC injection issues in solar inverters?

NEC 690 covers solar photovoltaic (PV) systems, and specific sections related to grounding, overcurrent protection, and disconnect requirements are relevant.

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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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Possible Causes:

Failed or degraded output filter capacitors within the inverter.
Asymmetrical switching of the inverter's IGBTs or MOSFETs.
Issues with the inverter's DC offset correction circuitry.
Grounding problems or neutral-ground voltage issues in the AC wiring.
DC leakage current from the PV array due to damaged panels or insulation faults.
External DC sources injecting current into the AC grid.

Critical Safety Precautions:

Working with solar inverters involves high DC voltages, posing a risk of electric shock and arc flash. Always disconnect both AC and DC power before servicing the inverter. Follow NEC 690 guidelines for safe system and maintenance of PV systems. Only qualified electricians should perform repairs on solar inverters.

Expert Tip:

Access the SolarEdge inverter's service menu (refer to the system manual for the key combination) and check the DC injection levels reported by the inverter's internal sensors. Compare these readings with the manufacturer's specifications to determine if the DC injection is within acceptable limits.

Technical Overview:

DC injection refers to the presence of a DC current component on the AC output of the inverter. Ideally, the AC output should be purely alternating current with zero DC component. DC injection can occur due to asymmetrical switching in the inverter's DC-AC conversion stage, malfunctioning filter capacitors, or issues in the MPPT circuitry. Hybrid inverters, which integrate battery storage, are particularly sensitive to DC injection problems since battery charge/discharge processes involve DC currents.

Symptoms:

The SolarEdge inverter displays a "DC Injection High" error, potentially leading to grid instability or inverter shutdown.

Solution:

1

Disconnect the AC power to the inverter using the AC disconnect switch. Verify absence of voltage with a calibrated multimeter.
2

Disconnect the DC power to the inverter using the DC disconnect switch. Verify absence of voltage with a calibrated multimeter.
3

Using a clamp meter, measure the AC current on each phase at the inverter output to check for excessive DC current. A qualified electrician must perform this step.
4

Inspect the inverter's output filter capacitors for bulging, leakage, or other signs of physical damage. Replace faulty capacitors.
5

Test the inverter's IGBTs or MOSFETs for proper switching behavior using an oscilloscope. A qualified electrician must perform this step.
6

Check the grounding connections of the inverter and the PV array. Ensure proper grounding according to NEC 250.
7

If the issue persists, contact SolarEdge support for further troubleshooting or inverter replacement under warranty.

Prevention:

Regularly inspect the inverter's cooling system to prevent overheating, which can degrade components
Perform periodic insulation resistance tests on the PV array to detect DC leakage
Ensure the inverter firmware is up to date
Monitor the inverter's performance data via the SolarEdge monitoring portal to detect anomalies early