ABB sold its solar inverter division to Fimer in 2020, which affects how support and replacement parts are sourced today. If you own an ABB-branded UNO-DM, TRIO, or legacy PVI-series inverter (also sold under the ABB Aurora name), here’s what common fault codes mean and what your service options look like now that the platform has changed hands.
Common ABB / Fimer Error Codes
| Display Message / Code | What It Means | Severity |
|---|---|---|
| Grid Fault Codes | Inverter detected grid voltage or frequency outside its operating range. Usually transient; frequent recurrence warrants inspection. | Low – usually self-clears |
| Ground / Insulation Fault | Reported as a specific fault code on the display – indicates reduced insulation resistance in the DC wiring, often from moisture or connector degradation. | Safety hazard |
| Arc Fault Detected (varies by model, often a dedicated LED pattern) | Inverter’s arc-fault protection detected a potential DC arc condition. | Safety hazard |
| Internal Fault / Fan Fault | Broad hardware category, common on units 8+ years old, often related to internal cooling or power components. | Moderate |
| No Display, No Output | Full hardware failure – common on older UNO-DM and PVI-series units where components are aging out. | Moderate-High |
This covers the fault categories homeowners encounter most often. Exact display behavior varies across the UNO-DM, TRIO, and legacy PVI platforms – if your unit shows a message not listed here, note it exactly and a technician can look it up for your specific model.
Ground Fault and Arc Fault: Why These Codes Are Different
Most inverter fault codes affect performance – annoying, but not dangerous. Ground/insulation fault and arc fault codes are different. Both are safety detections built into the inverter specifically to catch conditions that can cause electric shock or start a fire, and both deserve a faster response than a typical production drop.
A ground/insulation fault means current is leaking outside its intended path, most often through damaged wire insulation, water intrusion, or a compromised connector. An arc fault means the inverter’s protection circuitry detected current jumping across a gap instead of flowing through an intact conductor – arc-fault protection has been required on residential PV systems since 2011 under NFPA 70, Article 690.11.
Resetting the inverter will often clear either code and let the system restart production. That reset does not fix anything – it only clears the fault flag. If the underlying wiring damage, moisture intrusion, or failed connector is still there, the condition can recur, sometimes without being safely detected and interrupted the next time. Repeatedly resetting a system that keeps throwing a ground fault or arc fault, instead of having it inspected, is how a manageable wiring issue turns into a safety event. If your system displays either of these codes, treat it as a signal to schedule a diagnostic inspection – not a nuisance to click through.
Why the ABB-to-Fimer Transition Matters for Repairs
Because ABB’s solar business was acquired by Fimer, replacement parts and warranty support for ABB-branded units now route through Fimer’s channels – and availability has narrowed over time. For many older ABB units, sourcing an exact replacement part is no longer practical, which shifts the repair-vs-replace decision toward full inverter replacement sooner than it would for an actively-supported platform.
Repair or Replace?
If your ABB or Fimer inverter is still within its original warranty window, replacement is typically covered – documentation from a licensed technician is required. Outside of warranty, and especially for units on the older PVI platform, full replacement is usually the more practical and cost-effective path given parts availability.
Important Safety and Liability Notice
This article is provided for general informational purposes only and does not replace a professional, on-site diagnosis. Solar inverters operate at high DC and AC voltages and involve real fire and shock hazards; do not open, probe, or attempt to repair internal inverter components yourself. ElectriCare, Inc. makes no warranty as to the completeness or current accuracy of manufacturer error codes referenced here, which vary by model, firmware version, and installation, and assumes no liability for property damage, injury, or system damage resulting from actions taken based on this content. If your system displays a ground fault, arc fault, or any code you’re unsure about, do not repeatedly reset the inverter to clear it – contact a licensed technician for evaluation.
Related Reading
- Inverter Errors and Failures: Complete Troubleshooting Guide
- Solar Arc Fault Errors: Causes, Risks and What to Do
- Your String Inverter Is Failing: Repair, Replace, or Upgrade?
- Help for Orphaned Solar Systems
Get Your ABB / Fimer System Diagnosed
ElectriCare diagnoses and services ABB and Fimer inverters, including systems left without manufacturer support due to the ABB-to-Fimer transition. Ground fault and arc fault calls are treated as priority service.
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Sources and Further Reading
- Fimer Official Product & Support Documentation
- NFPA 70, Article 690 – Solar Photovoltaic Systems
- CALSSA – California Solar and Storage Association