A grid connection failure means the inverter tried to connect to the utility grid and did not succeed, so it is not feeding power. On FIMER/ABB string inverters this shows as warning W046 'Grid conn. fault', with the yellow or alarm LED lit. The manuals list three causes: no grid present, DC input undervoltage, or someone manually disconnecting the inverter during the connection sequence. SMA inverters report similar events ('Waiting for grid voltage' or 'Grid connection installation failure') and tell you to check the grid and fuses. To tell the causes apart, measure the AC grid voltage and frequency and compare them with the connection thresholds, and check the DC input voltage for an undervoltage condition. The inverter retries on its own. If the fault persists after several attempts, switch the inverter off and on again, and contact customer assistance if it still does not connect.
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observed_asc1 verified · fact Inverter fault indicator light
The yellow LED on PVS models, or the alarm LED on UNO-DM models, comes on with W046.
tbl=52.r1 h=9205e4e0b34btbl=45.r6 h=a8b1ee8ba45ctbl=38.r2 h=89f7284ff292tbl=36.r2 h=89f7284ff292verified by: review-workflowverified on: 2026-10-23
c2 drafted · lead Zero AC grid voltage
One logged cause of W046 is a missing grid during the connection sequence. SMA inverters report a similar event as waiting for grid voltage.
tbl=52.r1 h=9205e4e0b34btbl=45.r6 h=a8b1ee8ba45ctbl=38.r2 h=89f7284ff292tbl=36.r2 h=89f7284ff292review note: support check: partial - Missing grid is a logged cause of W046, but the passages give no voltage/power signal patterns or SMA 'waiting for grid voltage' link (that's in other passages not cited here).; review: partial - The rows support Missing grid as a logged cause of W046, but nothing in the cited passages backs the SMA 'waiting for grid voltage' sentence.
c3 verified · fact Low DC input voltage
An input undervoltage (Input UV) error during the grid connection sequence also logs W046.
tbl=52.r1 h=9205e4e0b34btbl=45.r6 h=a8b1ee8ba45ctbl=38.r2 h=89f7284ff292tbl=36.r2 h=89f7284ff292verified by: review-workflowverified on: 2026-10-23
c4 drafted · lead Grid voltage outside limits
SMA: the connection is refused when the grid voltage or frequency is outside the valid country-specific thresholds.
review note: support check: partial - Passages say voltage outside valid thresholds prevents connection and grid failure includes country-specific voltage/frequency deviation, but don't explicitly say SMA refuses connection or tie to this fault's frequency.; review: partial - The SMA passage says connection is not possible when the voltage is outside the valid thresholds, but the cited passages don't tie the frequency part of the note, or the word 'country-specific', to refusing connection; those words only appear in…
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