Symptoms:
The EI Inverter log reports the following message: Error Code 201 - Residual Current High
Cause
The inverter has detected a high residual current indicating that there is an issue with DC wiring, possibly due to:
- Chafed, exposed, or pinched wiring.
- Moisture ingress- connectors, j-box, switchgear
There may be unfamiliar terms in this procedure. It is highly recommended that you read this article before proceeding: PV Array Ground Fault Troubleshooting
Troubleshooting should be performed by qualified personnel
Resolution
Step 1. Turn off power to the system.
| 1. Turn off EI Battery. |  |
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2. Turn off EI Inverter power switch and external DC disconnect (if applicable). |
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| 3. Turn off EI Inverter AC disconnect. |  |
Verify the system is de-energized
We want the installer to be safe while conducting these tests. Use a multimeter to verify the following:
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1. Inverter GRID/BACKUP terminals L1 and L2 measurement read 0V AC. |
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2. Inverter GRID/BACKUP terminals L1 to N and L2 to N read 0V AC. |
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3. Inverter battery positive to negative terminal reads 0V DC. |
Step 2. Check inverter grounding conductor torque.
| Ensure the inverter EGC is properly torqued on the internal grounding bar: 1.0 Nm. |  |
| Verify proper inverter EGC torque in the main service entrance. Check panel specs. |  |
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Verify proper torque on inverter external GEC screw (if used): TBD |
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Did the EI Inverter torque spec ratings match the installer terminal torque checks?
YES - Continue to Step 3.
NO - If torque was corrected, then proceed to Step 6 - System Turn On.
Step 3. Check PV grounding conductor integrity.
WARNING: Although the PV DC disconnect is off, there is still lethal voltage in the array DC wiring. These next steps are a visual inspection only. It is recommended that the installer initiate rapid shutdown, so that there is no potentially lethal voltage on the DC conductors.
| Hand-over-hand each PV array EGC |  |
| Look for chafing, cracks, blisters, exposed copper |    |
Did the installer find any wiring issues?
NO - If wiring inspection passes, continue to Step 4.
YES - If faulty wiring is found, correct the wiring, and then proceed to Step 6 - System Turn On.
Step 4. Check for moisture ingress.
This is a tricky procedure, as moisture that may have caused the fault could evaporate before the installer is on site. Note the time of day when the error is recorded. If it always happens in the morning, but clears by the afternoon, then moisture is probably the cause.
Have the installer look for discoloration or corrosion. These are tattletales for moisture ingress. Check the following areas:
| PV module connections |  |
| Conduit |  |
| Junction Box |  |
| Inverter | |
Did the installer find evidence of moisture intrusion?
NO - Continue to Step 5.
YES - If moisture was found, correct the issue. then proceed to Step 6 - System Turn On.
Step 5. Perform Megger test.
If the installer has a Megger, then ask them to perform a Megger test on all the modules and the DC wiring, starting with the homeruns. See videos below.
Reference: Megger and Insulation Tests
If the installer does not have a Megger, proceed to Step 7.
Did the Megger test find the fault?
YES - Continue to Step 6.
NO - Proceed to Step 7.
Step 6. Perform System Turn On.
- Turn on Battery
- Turn on Inverter DC power switch
- Turn on inverter AC disconnect
Step 7. If the fault still exists, call Tigo Support for further troubleshooting.
Additional Reading:
PV Array Ground Fault Troubleshooting
Videos: