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Fronius · Fronius Symo 3.0–20.0 (three-phase grid inverter, SnapINverter) · Procedure

How to switch a Fronius Symo inverter off and on safely

Summary (editorial)

The manual describes the order for disconnecting AC and DC and the waiting time before any work. Inside the inverter is for qualified staff only.

✎ editorial – written from the cited sources, not a manufacturer statement. Status: draft.

From the manufacturer's documentation (English source wording, with page)

  1. Turn off the automatic circuit breaker[1]
  2. Turn the DC disconnector to OFF[2]
  3. Turn the DC disconnector to ON[3]
  4. Switch on the automatic circuit breaker[4]
  5. Orange status LED lights up if STATE codes are shown on the display[5]
  6. Green operating LED lights up all the time while energy is fed into the grid[6]
  7. Status codes may appear briefly; if inverter continues working there was no fault[7]
  8. Before opening: disconnect input and output, wait 5 minutes for capacitors[8]

⚠ Work on refrigerant circuits, mains electricity and PV DC wiring is for qualified technicians only.

The Polish page has more detail (plain-language explanation, safe checks, guides): Read in Polish →

Sources

Every statement has a footnote to the document and PDF page. “Quote verified” means the quote was found automatically in the text of that page.

  1. [1] Fronius Symo 3.0-3 – 20.0-3, Fronius Eco 25.0-3 – 27.0-3 – Operating Instructions (42,0410,2028, ed. 044-12062025) (42,0410,2028 (044-12062025)) , p. 50 official manufacturer document quote verified Turn off the automatic circuit
  2. [2] Fronius Symo 3.0-3 – 20.0-3, Fronius Eco 25.0-3 – 27.0-3 – Operating Instructions (42,0410,2028, ed. 044-12062025) (42,0410,2028 (044-12062025)) , p. 50 official manufacturer document quote verified Turn the DC disconnector to the
  3. [3] Fronius Symo 3.0-3 – 20.0-3, Fronius Eco 25.0-3 – 27.0-3 – Operating Instructions (42,0410,2028, ed. 044-12062025) (42,0410,2028 (044-12062025)) , p. 50 official manufacturer document quote verified Turn the DC disconnector to the "ON" switch position.
  4. [4] Fronius Symo 3.0-3 – 20.0-3, Fronius Eco 25.0-3 – 27.0-3 – Operating Instructions (42,0410,2028, ed. 044-12062025) (42,0410,2028 (044-12062025)) , p. 50 official manufacturer document quote verified Switch on the automatic circuit breaker.
  5. [5] Fronius Symo 3.0-3 – 20.0-3, Fronius Eco 25.0-3 – 27.0-3 – Operating Instructions (42,0410,2028, ed. 044-12062025) (42,0410,2028 (044-12062025)) , p. 26 official manufacturer document quote verified If status codes (STATE Codes) are shown on the inverter display
  6. [6] Fronius Symo 3.0-3 – 20.0-3, Fronius Eco 25.0-3 – 27.0-3 – Operating Instructions (42,0410,2028, ed. 044-12062025) (42,0410,2028 (044-12062025)) , p. 26 official manufacturer document quote verified all the time while energy is being fed into the grid
  7. [7] Fronius Symo 3.0-3 – 20.0-3, Fronius Eco 25.0-3 – 27.0-3 – Operating Instructions (42,0410,2028, ed. 044-12062025) (42,0410,2028 (044-12062025)) , p. 51 official manufacturer document quote verified Status codes may sometimes appear briefly as a result of the in
  8. [8] Fronius Symo 3.0-3 – 20.0-3, Fronius Eco 25.0-3 – 27.0-3 – Operating Instructions (42,0410,2028, ed. 044-12062025) (42,0410,2028 (044-12062025)) , p. 10 official manufacturer document quote verified Wait for the capacitors to discharge (5 minutes).