Deye SUN Hybrid F35 — No AC Grid (No Utility Detected)

What it means: The inverter cannot see the utility supply. Deye's single-phase manual lists F35 as "No AC grid" with the description "No Utility". During load shedding, or any outage, this is the inverter correctly reporting that the grid has gone — it is a status, not a breakdown. F35 only becomes a fault worth chasing when it shows while your neighbours clearly have power, or while your own meter is live.

Why does Deye show F35?

The Pakistan factor

In Pakistan F35 is mostly not a fault at all: it is what a Deye-platform hybrid displays every time load shedding starts, and the correct response is to do nothing. The trouble is that panic-restarting a healthy system during an outage is how people damage them, and a lot of "my inverter is showing an error during load shedding" calls are this code behaving exactly as designed. Two local patterns are worth separating from that. On weak end-of-line feeders the supply can be nominally present but so far out of range that the inverter will not connect, which shows up alongside grid-voltage codes rather than as F35 alone. And where the house has been rewired around a generator or a manual changeover switch, F35 that persists after the grid returns is usually the changeover left in the wrong position, not an inverter fault. Note also that F35 appears in Deye's single-phase SG04LP1 fault table; the three-phase SG04LP3 manual we checked does not list it, so a three-phase unit showing something else for a lost grid is not a contradiction.

How to fix it (safe to try yourself)

  1. First, confirm whether the grid is actually gone. Deye's own step 1 is "please confirm grid is lost or not". Check a light or socket that is fed directly from the utility rather than through the inverter, or ask a neighbour on the same feeder. If the area is out, F35 is correct and nothing needs fixing.
  2. Check the schedule. If F35 tracks your area's load-shedding hours, the code is doing its job. It should clear on its own within a minute or two of the supply returning.
  3. Look at the switch between the meter and the inverter. Deye's step 3 is to check that the switch between inverter and grid is on. Resetting a tripped breaker at your distribution board once is a normal homeowner action — but if it trips again immediately, leave it off and call an electrician. A breaker that will not stay in is reporting a fault, not asking to be pushed harder.
  4. Note whether the grid light comes back when mains returns. If the utility is clearly on and F35 stays, write down the time and how long it lasts. That log is what a technician needs.
  5. From here it is an electrician's or installer's job. Deye's step 2 is to check the grid AC connection, which means opening the inverter's terminal compartment on an isolated system — not something to do with the unit energised. Do not open the inverter, the meter box or the main distribution board yourself. A loose or burnt grid terminal is a fire risk and it is exactly what this check is looking for.
  6. If the wiring checks out and F35 still latches with a healthy supply present, Deye's manual ends at "seek help from us" — the grid-sensing side of the inverter needs service.

References