GoodWe Error 25 — Relay Check Failure

What it means: The inverter's grid relay failed its self-test, so the unit refuses to connect to the utility. GoodWe names two causes and neither of them is the relay — neutral and ground cables not well connected at the AC terminals, and loss of the utility ground. The self-test needs a sound neutral-earth reference to pass, so a bad earth reads as a bad relay. The ET-series manual adds the genuinely internal versions, an abnormal or short-circuited relay and an abnormal control circuit.

Why does GoodWe show 25?

The Pakistan factor

Error 25 and error 10 are the two codes that define GoodWe ownership in Pakistan, and both are earthing faults wearing an inverter's error number. A single corroded earth rod in dry Punjab or Sindh soil, a distribution board where neutral and earth were never bonded, and a back-up circuit run by the cheapest available hand will produce 25 for years. No firmware update fixes an earth electrode. Insist that your installer records the neutral-to-ground voltage and the back-up neutral-to-ground resistance at handover and again after any DB rework, because both numbers drift as connections corrode and as the soil around the electrode dries out over successive summers. If error 25 is present together with any tingle from earthed metal anywhere in the house, treat it as an emergency and switch off at the AC breaker before calling anyone.

How to fix it

  1. One controlled power cycle first. Switch the AC breaker off, switch the inverter's DC switch off, wait five minutes, then restore DC and finally AC. That order matters. If you are not comfortable operating the DC switch, leave the whole step to your installer — nothing is lost by waiting.
  2. If 25 returns, do not repeat the restart. GoodWe's next two steps are measurements and both are electrician work on live equipment. Ask your installer to take them and to write the numbers on the handover note.
  3. Measurement one — the voltage between ground and neutral on the grid side must be less than 10 V. Measurement two — the resistance between ground and neutral on the back-up output must be less than 10 ohms. These are pass or fail numbers from GoodWe, not opinions, and they turn an argument with your installer into a reading.
  4. If neutral-to-ground voltage comes back above 10 V, the fault is your earthing and bonding, not the inverter. Do not open the meter box or the distribution board yourself to chase it. A missing or floating neutral is a shock and fire hazard for the whole house and it needs a qualified electrician, not a screwdriver.
  5. If both measurements pass and 25 still latches, the relay or control circuit is faulty and it goes to the GoodWe service centre. Do not open the inverter. There is no owner-serviceable relay inside it.

References