Warning What does this mean?
Your system is down or running degraded, but this is not an immediate safety danger. Work through the safe steps below.
Solis Inverter DCinj-Fault — High DC Injection Explained
DCinj-FAULT means your Solis inverter measured too much DC current leaking into its AC output — “high DC injection current” in the manual’s words. Grid rules require that DC component to stay near zero, so the inverter shut down. Try one documented restart; if the code returns, your installer needs to check the PV string wiring and the inverter’s power stage.
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
Your inverter’s job is to output clean alternating current. A small DC offset on that AC output — called DC injection — is unavoidable in practice but tightly limited by grid standards, because even modest DC currents can saturate the transformers on the distribution network and cause overheating upstream.
DCinj-FAULT means the inverter’s monitoring measured DC injection above its protection threshold and stopped feeding power. In other words, the inverter caught itself producing non-compliant output and disconnected before it could affect the grid.
Solis’s own troubleshooting remedy for this code points first at the PV array wiring — specifically, checking the string polarity for reversely connected strings. Reversed polarity on a string can disturb the inverter’s operating point enough to drive DC onto the output. If the wiring checks out, the remaining suspect is the inverter’s own conversion stage, which is why a persistent DCinj-FAULT ends with professional diagnosis of the power electronics.
For a homeowner, the practical takeaway is simple: this code is about power quality on the AC side, not about your panels underperforming. A one-off trip after a grid disturbance is plausible; a repeating trip means something is systematically wrong — either in the array wiring or inside the inverter — and the manual’s remedy chain exists precisely to separate those two cases.
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
- A reversely connected PV string — Solis’s published remedy specifically calls for checking string polarity, making this the documented first suspect.
- A transient measurement glitch — the protection circuit tripped on a momentary disturbance and clears with a restart.
- An internal converter or power-board fault — if the wiring is correct and the fault persists, the inverter’s own power stage is producing the DC offset and needs professional service.
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
Call your solar installer if DCinj-FAULT appears again after one clean restart. Your installer needs to verify every string’s polarity and test the inverter’s power stage — the two causes Solis’s own remedy chain points to. String polarity checks and power-board diagnosis both involve live DC work that only qualified personnel may perform. Do not open the inverter or rewire any strings yourself.
Frequently asked questions
What is DC injection, in plain terms?
It is a small amount of direct current riding on top of the alternating current your inverter sends out. A trace is normal and harmless, but grid standards set a strict ceiling because DC current can overheat the transformers on the utility network. Your inverter watches this continuously and trips DCinj-FAULT if the ceiling is breached.
Can DC injection damage my home appliances?
Not from this event. The inverter detected the excess and disconnected itself before it could matter — and the amounts involved are small by appliance standards. The protection exists mainly to protect utility equipment, and it did its job.
Why would reversed string polarity cause this?
Reversed polarity forces parts of the inverter’s input stage to operate outside their designed range, which can unbalance the conversion and push a DC component onto the output. It is also simply dangerous wiring, which is why the manual flags it first and why only an installer should investigate.
Will a restart fix DCinj-FAULT?
Sometimes — if the trip was a transient measurement glitch, one clean restart clears it for good. But if reversed wiring or a failing power stage is the cause, the code will come straight back. One restart is the right test; repeated restarts are not a fix. And if the code returns even once after that single restart, stop testing — the manual’s next steps are string-polarity checks and power-board diagnosis, both strictly installer work.
Need a professional?
This fault may need professional diagnosis. Contact a qualified solar electrician in your area.
Sources: meaning and troubleshooting verified against the manufacturer's documentation — Solis S6-GC3P(37.5–60)K Installation and Operation Manual, Ver 1.0 (Ginlong Technologies, 2024), Table 8.1 Troubleshooting: DCinj-FAULT — High DC injection current; Solis Three Phase Inverter Manual 3P(215-255)K 5G ENX Ver 1.3 (ginlong.com): remedy references checking the inverters’ PV string polarity for reversely connected strings.