An I leak is a current leakage to ground. This can happen on the AC or DC side of the inverter circuit.

Typically the I leak is a kind of ground fault that occurs when the inverter is in operation and CURRENT is flowing through the inverter circuit ( Parasitic Capacitance ). There are several things that can cause this fault listed below that we have found in the field so far. This is not a comprehensive list but ideas to use when troubleshooting. 

  1. The DC + or - input of a DC string is swapped with another string in a different position, or a different inverter. If the string is crossed with another inverter strange things can happen, and I-leak is probable. Also you may only have one inverter that runs. If its swapped at the same inverter, you may see under production, and odd behavior from the inverter. This may also be at an RSD level.
  2. Minor ground faults are also a cause of Ileaks, especially if the wire insulation is not broken but reduced in the case of abrasion, or some other action that may cause the insulation to be less in a critical point. Water in conduit or in junction boxes can also cause Ileaks. This can include High humidity depending on the conditions. 
  3. Running long wires to your array or to your transformer/Disconnect can cause an I-Leakage if your wires are undersized.  Be sure to do the appropriate analysis of your wire current capacity for the distance it's running. This may also indicate an issue with the transformer itself.
  4. Low quality AC conductors can cause this issue if the wire is not in good shape from the wire pull or has damaged insulation in multiple locations. 

Below is the meaning of each alarm code (pro1-pro4) This indicates how much current is leaking from the system. 








Dependent on inverter size in kW. mA threshold corresponds with kW size (for 125kW, ILeak-Pro4 setting is 1200 mA, for 60 kW, it is 600 mA, etc)

To test the integrity of AC conductor insulation using a megohmmeter, use the following procedure:

  1. The AC breaker must be OFF to isolate the conductors under test from AC voltage, as well as from other AC circuit components.  Ensure that the AC switch on the inverter is OFF before testing to isolate the inverter's AC circuitry from the high DC test voltage.  If the inverter does not have an AC switch, then the AC wires MUST be unlanded from their terminal blocks at the inverter prior to testing.
  2. We recommend a 1000 Vdc test voltage for 600 Vac rated conductors, measured line to ground and line to line.  The test voltage should applied for 30 seconds, or until the megohmmeter reaches its maximum resistance for the test voltage being used and holds the maximum resistance for 5 seconds ("pegs out").
  3. If any AC conductors test at 0 MOhms resistance or markedly lower insulation resistance than the others, then both ends of the conductor must be unlanded and the conductor re-tested to establish that the issue is confined to the conductor and no other system components.
Victor is the author of this solution article.

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