Growatt Error 420: GFCI Fault
Error 420 is a GFCI (Ground-Fault Circuit Interrupter) fault. The GFCI is the protection that watches for dangerous leakage to ground, so when it reports a fault, the inverter stops. Because it is a safety device, a persistent Error 420 should be checked rather than repeatedly reset.
What it usually means
- A real ground-leakage condition the GFCI caught (related to Error 201 and Error 203, often moisture-driven).
- A fault in the GFCI circuit or power board itself.
- A transient that a restart clears.
What to do, safely
- Restart the inverter. AC breaker off, then the DC isolator, wait 5 minutes, restart. A one-off Error 420 can clear, especially if morning moisture was the trigger.
- Note the pattern. If it appears with damp weather and clears as things dry, it leans toward a ground-leakage cause like Error 203.
- If it keeps returning, stop. Don't repeatedly override a ground-fault protection.
- Contact your installer or Growatt. They check for a real ground fault and confirm whether the GFCI circuit or power board needs service.
When to bring in a professional
Error 420 involves ground-fault protection, a safety function. A persistent fault should be inspected for a real ground leak or a board issue, not cleared and ignored.
Related Growatt codes
Sources
- Growatt inverter user manual and error-code reference (Error 420 = GFCI fault; restart, replace power board or contact Growatt if it continues).
- Growatt installer documentation.
⚠️ Safety disclaimer. Error 420 involves ground-fault protection. Solar inverters carry lethal DC and AC voltage. This guide covers a safe power cycle only. Ground-fault and board checks must be done by a licensed installer or Growatt technician.