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Growatt Error 408: Over Temperature

Updated June 2026 · Reviewed for technical accuracy · ~3 min read

Error 408 means the temperature inside your Growatt rose above its safe operating limit, so the inverter throttled down or shut off to avoid damage. It is a protective response, and almost always about cooling and airflow rather than a broken part. Help it run cooler and it usually goes away.

Why a Growatt overheats, most common first

  • Poor ventilation or direct sun. It is in a hot, enclosed spot or taking direct sunlight on the casing.
  • Dust or blockage. The vents or cooling fan are clogged with dust, lint or insects.
  • Midday heat at full output. Peak sun plus a hot day plus maximum power pushes it over the limit.
  • Something covering the unit. Items leaning against it or stored on top trap heat.

How to fix it safely

Let it cool first The casing can be hot during a thermal fault. All steps are external; don't open the unit.
  1. Power it down to cool. Turn the inverter off and leave it for at least 10 minutes so the temperature drops back to a safe level.
  2. Make sure nothing is covering it and clear at least 30 cm (12 in) of space around it, so air can move freely.
  3. Get it out of the sun. If sunlight hits the unit, shade it or plan to relocate it somewhere cool and ventilated.
  4. Clean the vents. With it off, gently clear dust from the external air vents and fan grille. Don't open the case.
  5. Restart and watch. If Error 408 stays away through the next hot part of the day, it is solved.

Quick decision flowchart

Error 408 appears
↓ cool down, uncover, improve airflow, clean vents
✅ Stays clear through midday heat → solved. Keep it ventilated and shaded.
❌ Returns with good airflow and a clean, shaded unit → fan or sensor fault.
↓
If it keeps returning despite good cooling, contact your installer or Growatt.

Stop it coming back

Error 408 is often a siting problem. The lasting fix is a cool, shaded, well-ventilated location with clear space around the unit. A shaded garage or exterior wall beats a sun-baked spot every time.

Related Growatt codes

Error 404, DC bus sampling Error 405, Relay failure Error 300, AC voltage

FAQ

Error 408 only happens around midday.

That is the classic sign of marginal cooling: peak sun, peak output and peak ambient heat all at once. Improve ventilation and shade. If it persists at midday, the location or the fan is the limit.

Is Error 408 dangerous?

The fault itself is the inverter protecting itself, which is good. The long-term risk is that running hot repeatedly shortens component life, so fix the cooling rather than ignoring it.

Sources

  • Growatt inverter user manual and error-code reference (Error 408 = over temperature; restart, ensure the unit is not covered).
  • Growatt installer documentation.
⚠️ Safety disclaimer. Solar inverters carry lethal DC and AC voltage even when "off", and the casing can be hot during a thermal fault. This guide covers external steps only. Never open the unit or work on wiring unless qualified. When in doubt, call a licensed installer or electrician.