SMA is one of the longest-standing string inverter manufacturers in the solar industry, and its Sunny Boy and Sunny Tripower lines remain in service on thousands of older residential systems. SMA reports faults as numbered codes on the inverter’s built-in display or through Sunny Portal monitoring.
Common SMA Error Codes
Error 3001-3005 (Grid Fault): The inverter has detected an issue with grid voltage or frequency outside acceptable range. Often transient and resolves on its own, but repeated occurrences point to a grid-side or utility connection issue worth having checked.
Error 4002 (Insulation Fault / Ground Fault): Similar to a ground fault on other platforms — a loss of insulation resistance in the DC wiring, frequently from moisture intrusion or damaged cabling.
Error 3501 (Arc Fault Detected): A safety-critical code. See our dedicated guide on arc fault errors for what this means and why it should not be dismissed.
Error 4003 / Fan Warning: Internal cooling fan fault. Left unaddressed, this leads to thermal throttling and eventually a full inverter shutdown from overheating.
Persistent Red LED, No Display: Common on Sunny Boy units 10+ years old — often points to failed internal power components rather than a wiring issue.
Repair or Replace?
SMA string inverters typically carry a 5-10 year standard warranty depending on model and year of purchase. Given how long SMA units have been in the field, many in service today are well past their original warranty window — which makes an accurate diagnosis (repair vs. full replacement) especially important before spending money on parts for an aging platform.
Related Reading
- Inverter Errors & Failures: Complete Troubleshooting Guide
- Solar Arc Fault Errors: Causes, Risks & What to Do
- Your String Inverter Is Failing: Repair, Replace, or Upgrade?
Get Your SMA System Diagnosed
ElectriCare technicians diagnose and service SMA Sunny Boy and Sunny Tripower systems, including units well outside their original warranty window.
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