Xantrex Solar Inverter Problems? Here’s What to Check

Xantrex GT Speaks in Plain English — Read the LCD First

Xantrex GT grid-tie inverters (now under the Schneider Electric umbrella) do not use numeric error codes the way many brands do. Instead, the front-panel LCD shows plain-language fault messages — “DC Voltage Fault,” “AC Voltage Fault,” “Ground Fault” — that alternate with the default “Inverter Offline” screen until the condition clears. That makes diagnosis straightforward: read the message, note the numbers beside it, and follow the manual’s fault table.

Quick Answer

If the LCD shows a DC, AC, or frequency fault, the condition is usually self-clearing: the inverter resumes automatically once the measured value returns to the allowable range (for example, DC between the model’s specified limits, typically 165–600 Vdc on early GT models, or 240–600 Vdc on later ones). A ground fault is the exception — the red LED comes on, the ground-fault fuse blows, and the manual requires a full shutdown, fuse replacement, and inspection by qualified personnel before restart. Aps1Off or DCUVSD1 faults at dawn and dusk are normal low-light behavior.

Diagnostic Checklist, in Order

1. Read the exact fault screen. The LCD shows the fault name and often a measured value (e.g. AC Voltage Fault with 280 V, Over Temp Fault with 81.4 °C). Write both down. Fault screens appear within seconds of the condition being detected.
2. Check the LEDs. Green means the unit is operating; the red fault LED means a fault is active. If only the red LED is lit and the display reads “Ground Fault,” stop here and call an electrician — this is a mandated professional repair, including fuse replacement.
3. For DC Voltage Fault: check the DC side externally. Confirm the DC disconnect is on and any external DC fuses are intact. The manual’s remedy: turn on DC breakers, check DC fuses, and verify connections at the positive and negative DC terminals are sound. If the inverter stops shortly after input current rises above 1 A, shut the unit off and have the ground-fault fuse inspected by a certified electrician before restarting.
4. For AC Voltage Fault or Frequency Fault: suspect the utility. These are utility faults per the manual — the inverter waits and reconnects automatically when voltage and frequency return to the specified range. Check your main-panel breakers are on; beyond that, the correct action is to wait, not to adjust anything.
5. For Over Temp Fault: check ventilation. The unit shuts down above 80 °C internally and restarts below 70 °C. Make sure nothing is blocking the inverter’s airflow and that it is not baking in direct afternoon sun with no clearance. This fault clears itself when the temperature drops.
6. For blank LEDs in sufficient sunlight: check breakers. Per the troubleshooting table, dark unit + no operation usually means the utility service panel AC and DC breakers are off. Turn them on in the commissioning sequence (DC first, then AC), and confirm AC voltage is within the model’s specified range.

For Unit Shutdown via Remote, check for external control. This message means the inverter was shut down by a computer connected to the RS-232 port, for example a monitoring or control system. If nobody in the household did this intentionally, check whether a third-party monitoring box or installer remote session is attached, and confirm with your installer before re-enabling the unit.

When to Call a Professional

Call a certified electrician or solar technician for any ground fault (fuse replacement and system inspection are explicitly required), for “Protection uP Not Responding,” for persistent DC voltage faults after breakers and fuses check out, for repeated over-temperature shutdowns, and for anything requiring the inverter to be opened. The homeowner boundary is the LCD, the LEDs, the breakers, and the external disconnects — all probing and fuse work inside the unit is qualified-personnel territory.

Frequently Asked Questions

What does “Aps1Off” mean on my Xantrex GT?

It means the auxiliary power supply in the inverter is off, usually during periods of insufficient PV power — dawn, dusk, or heavy cloud. It is self-clearing and requires no action; it recovers when the array produces power again.

Why does the inverter show a fault every evening?

Evening faults like DCUVSD1 and Aps1Off are normal low-light behavior as array voltage drops at night. They appear first at dusk and clear automatically at sunrise. Only daytime faults need investigation.

Can I replace the ground-fault fuse myself?

No. The Xantrex manual states the system must be shut down completely, the fault corrected, and the fuse replaced before restart — and that troubleshooting a grounding fault should be performed by qualified personnel. A blown ground-fault fuse means current took an unintended path, which is exactly the situation that warrants a professional.

My Xantrex shows “Neutral Loss Detected.” What is that?

On North American configurations, it means the phase-to-neutral voltage is outside the allowable range — either a utility fault or a phase-to-neutral line that is not connected properly. Check with your utility first, then have an electrician verify the wiring.

Related Error Codes

• Fronius STATE 208 — Mains Relay Does Not Close
• SolarEdge 8×58 — Isolation Fault
• Sungrow 039 — Low Insulation Resistance