Symptom
Ground fault alarm or trip
- ID
symptom:ground-fault- IRI
https://solarlattice.org/kb/symptom/ground-fault- Status
- active
- Also known as
- insulation fault, leakage current high, Insulation resistance low, GFCIErr, IsolationErr
A ground fault happens when current leaks to ground through an unexpected connection or weakened insulation. This lowers efficiency and creates a safety hazard. It usually shows up at the inverter as a low insulation resistance alarm, a high leakage current alarm or a red fault light, and the inverter opens the circuit. If an inverter shows a ground fault light, put on the right PPE before touching any metal on the system. To find the faulted string, isolate all strings at the fuse holders. Then add one string at a time and restart the inverter until the alarm comes back. Trace that string for leakage to earth. Common causes are damaged cable insulation, a wire pinched between the module and the racking, or wire rubbing on a rough conduit edge as it expands and contracts. Connector defects can also cause it, especially poorly crimped or mismatched connectors. Check these by visual and tactile inspection, IR imaging under load and insulation resistance testing. Broken module glass or a cracked backsheet can also cause ground faults. With broken glass, the fault can be intermittent and appear mostly on rainy days. A clamp-meter check showing different current on the positive and negative conductors also points to a fault.
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- sentence 2: support check: partial - The alarms (IsolationErr, GFCIErr) and red light are in the evidence, and u13 says the inverter opens the circuit, but 'usually shows up' as these is a mild generalization.
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Claims
observed_as
c1 verified · fact
Low insulation resistance alarm
Inverter protection code IsolationErr (insulation resistance low); the advised response is to isolate strings and add them back one at a time until the alarm returns, then trace that string for leakage to earth.
verified by: joshuahamsaverified on: 2026-10-20review note: support check: partial - IsolationErr and the add-one-string-at-a-time procedure are stated, but nothing says the inverter stops exporting (model_103.W) while the alarm is active.
c2 verified · fact
High leakage current alarm
Inverter codes GFCIErr (leakage current high) and Fault0090 (dynamic leakage current high); found by the same one-string-at-a-time procedure.
verified by: joshuahamsaverified on: 2026-10-20review note: support check: partial - GFCIErr and Fault0090 with the one-string-at-a-time procedure are stated, but output dropping to zero on trip is not stated.
c3 verified · fact
Inverter fault indicator light
A red light on the inverter can mean a ground fault may be present. Do not touch metal parts until the right PPE is on.
verified by: joshuahamsaverified on: 2026-10-20
c4 verified · fact
Unequal positive and negative current
Clamp-meter readings on the positive and negative conductors should match. A difference points to a possible fault.
verified by: joshuahamsaverified on: 2026-10-20
c5 verified · fact
Abrupt DC power and voltage change
Ground faults were detected as sequential changes in the mean DC power and voltage at the array output.
verified by: joshuahamsaverified on: 2026-10-20review note: support check: partial - The paper monitors mean DC power and voltage to detect ground faults as sequential changes, but the evidence does not say ground faults specifically showed abrupt changes in both quantities.
Referenced by
Data