Warning What does this mean?
Your system is down or running degraded, but this is not an immediate safety danger. Work through the safe steps below.
Growatt Inverter Auto Test Failed — Why It Happens and What to Do
If your Growatt shows “Auto Test Failed” (Error 407), the inverter’s Italy-only protection self-test did not pass. This automatic test exists only on inverters configured for the Italian grid standard (CEI 0-21) — it proves the inverter’s anti-islanding and protection trips work before the unit is allowed to feed power into the grid. It is almost never a hardware failure: the usual reasons are an unstable grid during the test or the wrong country setting at commissioning. Restart the inverter and run the auto test again. If it fails a second time, call your installer or Growatt service.
What should I do first?
Two quick questions — we'll point you to the right starting point.
Is this code still showing on your inverter's display?
Is your system producing power right now?
What this code means
Every grid-tied inverter sold for the Italian market has to prove, on demand, that its protection functions trip at exactly the voltages and frequencies the CEI 0-21 standard requires. Growatt builds this proof into the firmware as the “auto test”: the inverter deliberately nudges its own trip thresholds and checks that it disconnects when it should. It normally runs once, at commissioning, and then stays quiet for the life of the system.
Error 407 is simply the record that this self-examination did not complete cleanly — “Auto test didn’t pass,” in the manual’s words. On the Growatt Modbus protocol it appears as fault type 24. The important thing to understand is what the code does not say: it does not say a protection component is broken, and it does not say your panels or wiring are faulty. It says the test itself could not be finished under the conditions at the time.
Why would a self-test fail on a healthy inverter? Because the test needs a calm, steady grid — if voltage or frequency wobbles during network switching, after an outage, or on a weak feeder, the measurements won’t line up with the expected trip points and the test aborts. The other classic reason is configuration: the auto test only runs on units set for Italy, so a wrong country setting at commissioning can produce a failure with nothing wrong with your hardware. While 407 shows, the inverter holds itself off the grid as a precaution; your home keeps running on grid power.
What is this downtime costing you?
Rough estimate while your system isn't producing. Adjust the numbers to match your setup.
≈ – kWh of lost production per day.
Estimate only — assumes ~80% real-world output vs. nameplate. Actual losses depend on weather, shading, panel direction, and your tariff.
Common causes
- An unstable grid while the test ran — utility switching, a recent outage, or a weak feeder can make the measurements drift.
- Wrong country or grid-standard setting selected at commissioning — the auto test is an Italy-only function, and a mismatched setting is a common reason for a spurious failure.
- The test was started too soon after a grid disturbance — protection self-tests need a settled grid; running one minutes after the power came back is asking for a failure.
- A firmware or configuration mismatch after a software update — rare, but a re-flash can leave protection settings out of step.
- A genuine internal measurement problem — the least likely cause, worth suspecting only after grid and settings are ruled out.
Safe steps to try
Work top to bottom, ticking off each step as you complete it. 0 of 5 done.
Is your inverter still under warranty?
Before paying for a repair, check — your installer may fix this free.
Based on typical standard warranty terms — always confirm with your warranty card or installer paperwork, as terms vary by model, region, and purchase date.
When to call an electrician
Call your installer or Growatt service if the auto test fails a second time, if your site is outside Italy (which means the country setting itself is wrong and must be corrected by a professional), or if 407 appears after a firmware update. Growatt’s official remedy for this error is short and final: restart the inverter, repeat the auto test, and if the problem still exists, contact Growatt. Only a qualified installer should touch country and protection settings — older Growatt documentation is explicit that cancelling or overriding the test is a decision for the power company, not the homeowner.
Frequently asked questions
I’m not in Italy — why is my inverter running an Italian test?
Then the country/grid-standard setting is almost certainly wrong, and that alone can explain the failure. Your installer needs to set the correct grid standard for your country; the auto test should not be running at all on a non-Italian configuration.
Does Auto Test Failed mean my inverter is broken?
Very unlikely. The manual lists no hardware remedy for 407 beyond a restart and a re-test. It is a test-procedure failure, not a component failure — the inverter is protecting itself by staying off the grid until the test passes.
Can I just skip the test and force the inverter online?
No. The self-test is a grid-code requirement, and older Growatt manuals state plainly that only the power company decides whether it may be manually cancelled. Forcing past it would put you offside with your grid connection terms.
Will it clear by itself?
No — the test has to be re-run deliberately from the menu. It won’t retry on its own, so a failed test sits on the display until someone addresses it.
Need a professional?
This fault may need professional diagnosis. Contact a qualified solar electrician in your area.
Sources: meaning and troubleshooting verified against the manufacturer's documentation — Growatt MIN 7000TL-X User Manual, §11.2 Inverter fault — “Auto Test Failed Error: 407 — Auto test didn’t pass. Restart inverter, repeat Auto Test, if problem still exist, contact Growatt.”; Growatt Troubleshooting for TL&MTL (Ver 1.2), Part I §1 — “Auto test function is only activated in model for Italy. Please make sure the grid (voltage and frequency) is normal. Restart the inverter and redo it.”