On SMA Sunny Island battery inverters, this event means the inverter has found voltage on its AC1 output. The display shows it as F158 (level 2) when the event belongs to the unit itself. When a slave unit in a cluster reports it, the display shows warning W159, W160 or W161 (level 1) for slave 1, 2 or 3. The code number tells you which unit to check. The sources do not name a root cause for this event, so do not assume a failure mode from the code alone. Before you work on the AC terminals, do an absence-of-voltage check between each pair of AC phases with a meter, as the inverter instructions show.
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observed_asc1 drafted · lead Inverter fault code display
On the SMA Sunny Island, voltage on output AC1 shows as display number F158 (level 2) for the unit itself. For slave units 1, 2 and 3 it shows as W159, W160 and W161 (level 1).
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