Critical What does this mean?
A safety-rated fault — there may be a risk of electric shock, fire, or equipment damage. Do not try to fix this yourself. Call a qualified electrician.
Solis Inverter ILeak-Pro and ILeak-Fault — Leakage Current Alarms
Solis inverters raise two related leakage-current alarms. ILeak-PRO 01–04 means the leakage-current protection has staged up through four escalating levels; ILeak-FAULT means the inverter has detected a hard leakage current fault and stopped feeding the grid. Both mean unwanted current is finding a path to earth somewhere in your AC or DC cabling — a genuine electrical safety issue. Solis's official manuals give the same first response for both: check the AC and DC connections, then call your installer if it persists.
What should I do first?
Two quick questions — we'll point you to the right starting point.
Is this code still showing on your inverter's display?
Is your system producing power right now?
What this code means
Every transformerless inverter continuously watches for current leaking where it should not go. Solis splits this job into two alarms, and the distinction matters. ILeak-PRO 01/02/03/04 is the staged protection: as measured leakage climbs through four thresholds, the inverter escalates its response — the higher the number, the more serious the leakage it has seen. ILeak-FAULT is the blunt instrument: a leakage current fault confirmed, feed-in stopped. Solis's official RS485 Modbus protocol document names them plainly — "Leakage current protection = ILeak-PRO" and "Leakage current fault = ILeak-FAULT" — and the 4G series user manuals describe ILeak-PRO 01/02/03/04 as "Leakage current protection" and ILeak-FAULT 01/02/03/04 as "High Grid leakage current."
In practice these alarms are the AC-side cousins of the DC isolation faults other brands report (GoodWe's Error 14, SolarEdge's isolation fault). Moisture is the usual suspect: damp junction boxes, aging cable insulation, condensation inside connectors, or a nicked cable lying in a wet cable tray. Because leakage grows with dampness, the classic signature is faults on wet mornings or after rain that vanish by afternoon — the same weather-following pattern as isolation faults, because the underlying physics is nearly identical.
Take these alarms seriously. Leakage current means electricity is already traveling outside its intended conductors, which is how shocks happen and how smoldering cable faults start. The inverter stopping is the protection doing its job. Unlike a grid-voltage fault, this one does not fix itself with better weather in any lasting sense — the damaged insulation or connection that let the current leak is still there when things dry out.
What is this downtime costing you?
Rough estimate while your system isn't producing. Adjust the numbers to match your setup.
≈ – kWh of lost production per day.
Estimate only — assumes ~80% real-world output vs. nameplate. Actual losses depend on weather, shading, panel direction, and your tariff.
Common causes
- Moisture ingress in DC connectors (MC4), junction boxes, or the AC connection area after rain or heavy dew.
- Aged, cracked, or rodent-damaged cable insulation on either the DC or AC side.
- A loose or corroded earth/ground connection, reducing the system's ability to drain leakage safely.
- Water pooling in cable trays or conduits, submerging a damaged cable section intermittently.
- Incorrect AC wiring (neutral/earth mix-ups) confusing the inverter's leakage measurement.
- A failing panel or inverter component leaking current internally — rare, but the reason persistent faults need professional diagnosis.
Safe steps to try
Work top to bottom, ticking off each step as you complete it. 0 of 5 done.
Is your inverter still under warranty?
Before paying for a repair, check — your installer may fix this free.
Based on typical standard warranty terms — always confirm with your warranty card or installer paperwork, as terms vary by model, region, and purchase date.
When to call an electrician
Leakage current is a shock and fire risk — this is electrician territory, not DIY. Call a qualified solar electrician immediately if ILeak-FAULT appears, if any ILeak alarm persists in dry conditions, if you smell burning or see discolored connectors, or if the alarm returns right after a restart. Finding the leak requires insulation-resistance testing on live DC circuits and opening connection boxes — never open the inverter or disconnect strings yourself.
Frequently asked questions
What is the difference between ILeak-PRO and ILeak-FAULT?
ILeak-PRO is the staged leakage-current protection (levels 01–04, escalating with the measured leakage). ILeak-FAULT is a confirmed leakage current fault that stops grid feed-in. PRO is the warning ladder; FAULT is the trip.
The alarm only appears on rainy mornings. Can I ignore it?
No. Moisture-driven leakage still means damaged insulation or a compromised connection, and it worsens over time. It also means leakage current is real whenever it is wet — exactly when someone might touch a panel frame or railing.
Does a higher stage number (03, 04) mean more danger?
It means the inverter measured higher leakage before responding. Treat 03/04 and any ILeak-FAULT as urgent and get an electrician out promptly.
Can I reset it by turning the inverter off and on?
A single restart is reasonable to see whether it was transient. If the alarm comes back, stop resetting and call your installer — repeated resets on a leakage fault achieve nothing and the underlying hazard remains.
Need a professional?
This fault is a safety risk — do not attempt to fix it yourself. Contact a qualified solar electrician in your area.
Sources: meaning and troubleshooting verified against the manufacturer's documentation — Solis (Ginlong) 4G series user manuals, official Ginlong documentation (ginlong.com) — alarm tables: ILeak-PRO 01/02/03/04 = "Leakage current protection", ILeak-FAULT 01/02/03/04 = "High Grid leakage current"; official solution: "1. Check AC and DC connection. 2. Check inverter inside cable connection." Confirmed in the official Solis RS485 Modbus protocol document: "Leakage current fault = ILeak-FAULT" / "Leakage current protection = ILeak-PRO".