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.
SMA Inverter Fac-Bfr or Fac-Srr — What the Grid Frequency Error Means
Fac-Bfr or Fac-Srr means the AC grid frequency is outside the allowable range. Your Sunny Boy assumes the utility grid is down and disconnects to prevent islanding — feeding power into a dead grid. The 'Bfr' or 'Srr' part is an internal SMA message with no meaning for you; you can ignore it.
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
SMA's manual defines these disturbance messages plainly: the AC grid frequency is exceeding the allowable range. For reasons of safety, the Sunny Boy disconnects from the grid so it never energizes lines that utility workers may believe are dead — this anti-islanding behavior is legally required, not a malfunction.
It appears during genuine outages, but also when the breaker feeding the inverter trips or a fuse blows, because from the inverter's perspective the grid has vanished either way. SMA's guidance confirms the logic: check the grid frequency and the grid connection, and if the frequency is within tolerance yet the message persists, look for intermittent connections.
Most residential SMA inverters monitor frequency continuously and will only reconnect after the grid has held steady inside the permitted band for a defined reconnection period. That waiting time is intentional — it keeps the inverter from rapidly cycling on and off while the grid is still settling, which would stress both the unit and the network.
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 utility power outage in your area — the most common cause by far.
- A tripped AC breaker or blown fuse on the solar circuit — the inverter sees no grid at all.
- A genuine grid frequency excursion, which is rare and usually tied to major grid disturbances.
- Intermittent AC wiring connections making and breaking contact.
- An incorrect country data set narrowing the permitted frequency window.
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 installer or electrician if Fac-Bfr or Fac-Srr persists while your home has normal power, if it appears repeatedly on clear calm days, or if you suspect loose AC wiring. SMA's guidance is explicit: when the grid frequency lies within the tolerance range yet the message keeps appearing, check for possible intermittent connections — that means a professional inspection of the AC wiring and the country data set settings. Do not open the inverter or touch its AC terminals yourself.
Frequently asked questions
What do 'Bfr' and 'Srr' actually mean?
Nothing you need to act on — SMA's own manual says they are internal messages with no meaning for the user. They only indicate which internal measurement channel raised the flag.
Is my inverter broken?
Almost certainly not. Fac-Bfr/Fac-Srr is the inverter doing its safety job during a grid problem. If it clears when power returns, the inverter is healthy.
Can I reset the message myself?
There is nothing to reset — the inverter reconnects automatically once it sees stable grid frequency for the required time. Just make sure your breaker is on.
Why does it appear briefly when power comes back after an outage?
The inverter waits and watches the grid for a stability period before reconnecting. During that window the frequency may still be settling, so the message can flash briefly. That is normal.
How long until my system produces power again?
Once the grid is stable and within the permitted frequency range, the inverter reconnects on its own — typically within minutes of a stable grid returning.
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 — SMA SB3800U User Manual (SMA America, Inc.) — Section 8 Error Messages: Fac-Bfr / Fac-Srr ('The AC grid frequency is exceeding the allowable range')