Growatt Inverter Error Codes Guide — 18 Faults and How to Fix Them

Every Growatt inverter — MIC, MIN, MID, MAX, SPH, SPA, and the new Noah — speaks the same fault language across firmware revisions. This guide unpacks the 18 error codes our service desk sees most often across the MIN 2500-6000TL-X X2 Pro, the MIN 2500-6000TL-XH hybrid, the SPH 4000-10000TL3-BH-UP commercial bank, and the MAX 100-150KTL3-X large utility platform. For each fault you get: what triggers it, the order in which to diagnose, and the fix that has actually cleared the code in the field.

How Growatt Error Codes Are Displayed

On a fault, the inverter LCD blinks red, sounds a soft buzz, and shows one of:

• Error: XXX — a numbered fault. The full list lives on page 38–44 of the model-specific manual.
• Warning: XXX — non-fatal alarm; the inverter keeps running but derates.
• Fault Code: 4XX — internal hardware error, usually requires Growatt service.

ShinePhone mirrors the same codes under Plant → Devices → inverter → "Event log". The export-to-CSV button is the fastest way to send a full history to Growatt warranty support.

1. Error: PV Reverse (Error 105 / "DC Reverse")

Cause: the PV+ and PV− leads are swapped on at least one MPPT input. Most common during initial commissioning.

Diagnose: on the LCD, the MPPT showing 0 V is the one with reversed polarity. Cover the panels, wait 5 minutes, then unplug the MC4 connectors and verify polarity with a multimeter.

Fix: swap the positive and negative MC4 connectors on the affected MPPT. Power-cycle the inverter. The error clears within 30 seconds.

2. Error: ISO Error (Error 502 / "Insulation Fault")

Cause: ground insulation resistance below the safe threshold (typically < 100 kΩ for transformerless models). Triggered by wet PV connectors, frayed cable insulation, or a panel with damaged backsheet.

Diagnose: the inverter measures PV+ to earth and PV− to earth on every power-up. Open the array DC isolator, disconnect MPPT strings one at a time, and reconnect after each reboot to identify the offending string.

Fix: inspect MC4 connectors for moisture ingress (most common after heavy rain in unsealed connectors). Re-crimp suspect terminals. If a panel backsheet is cracked, replace the panel.

3. Error: GFCI Fault (Error 503 / "Residual Current Detection")

Cause: leakage current to earth exceeds the safety limit (30 mA on most Growatt residential firmware, 300 mA on commercial). Often confused with ISO Error, but GFCI is a dynamic leakage event whereas ISO is a static insulation check.

Diagnose: common triggers — moisture in a junction box after rain, an MC4 connector seated proud of its housing, a cracked roof-side conduit drinking water.

Fix: dry the suspect connectors with a heat gun (low setting), re-seal with self-amalgamating tape, and replace any waterlogged junction boxes. Power-cycle. If the fault returns within hours, megger-test the string at 500 V — expect ≥ 1 MΩ to earth.

4. Error: Grid Loss (Error 410 / "No AC Connection")

Cause: the grid voltage on the AC side has dropped to zero or AC contactor has tripped. Frequent after utility outages, building-side breaker trips, or a loose terminal cooking under load.

Diagnose: check the AC breaker in the distribution board. Measure L-to-N voltage with a multimeter at the inverter's own AC terminal block — expect 230 V ±10%.

Fix: reset the upstream breaker. If it trips again, the cause is downstream — disconnect the inverter and check the breaker without the inverter load. A breaker that holds without the inverter usually means a loose AC terminal in the inverter — re-torque to 1.8 Nm.

5. Error: Grid Volt Fault (Error 411 / "Vac > Vmax")

Cause: grid voltage outside the allowable window for the country code (typically 184–264 V for single-phase 230 V codes). The inverter disconnects to comply with anti-islanding rules.

Diagnose: monitor the AC voltage trend in ShinePhone — short voltage spikes on a long, undersized AC cable run are the #1 cause. A 6 kW inverter on a 1.5 mm² cable can push the local voltage above 253 V during high export.

Fix: if the trend shows export-induced overvoltage, upgrade the AC cable to 6 mm² minimum or reduce the inverter export limit in ShinePhone's grid-code menu. If it's a genuine utility issue (real, sustained 250+ V), report to the DNO — they may need to retap the local transformer.

6. Error: Grid Freq Fault (Error 412 / "Fac out of range")

Cause: grid frequency outside the allowable window (typically 47.5–51.5 Hz on EU 50 Hz codes, 59.3–60.5 Hz on US 60 Hz codes). Usually a brief utility event.

Diagnose: check the event log for repeating Fac excursions. Persistent excursions point to a weak grid (rural Africa, remote farms) where local frequency drifts under load.

Fix: if isolated events, no action needed — the inverter recovers automatically within 60 seconds. If persistent, contact the DNO. As a temporary measure, switch to a wider grid code (e.g. "Australia A" instead of "Germany VDE") only with utility approval.

7. Error: BUS Voltage Fault (Error 405 / "BUS Overvoltage")

Cause: the internal DC link capacitor voltage exceeds the design limit. Most common cause is a transient surge from the PV side combined with a brief grid outage that prevented the inverter from dumping energy.

Diagnose: check whether the fault correlates with grid blips (storms, brownouts). One-off events are usually transient; repeating events suggest oversized PV input pushing the bus.

Fix: verify string voltage stays well under the max DC limit (550 V for X2 Pro/XH, 1000 V for 7000-10000TL-X, 1100 V for MAX). Add a DC surge protection device (SPD Type 2) between array and inverter if the site is in a lightning-prone area. Persistent Error 405 may indicate a failed capacitor — return for service.

8. Error: BUS Soft Start Fault (Error 406 / "BUS Voltage Low")

Cause: the bus capacitor fails to reach operating voltage during start-up. Typically a hardware fault, but sometimes triggered by very low PV input on a partly shaded morning start.

Fix: if irradiance is the cause, the error clears once the array reaches start voltage (60 V on MIN-X). If irradiance is good and the error persists, contact Growatt service.

9. Error: PV Voltage High (Error 102)

Cause: open-circuit string voltage exceeds the inverter's DC input ceiling. Most often a string sized for warm-weather operation that climbs above spec on a cold winter morning.

Diagnose: measure Voc at the inverter input on a cold morning before sunrise. Compare against the cold-temperature-corrected max: Voc(min ambient) = N × Voc(STC) × (1 + β × ΔT).

Fix: reduce panels per string by one if Voc exceeds the limit. If the array can't be physically reconfigured, swap to a higher-voltage inverter (e.g. MAX 100-150KTL3-X at 1100 V DC).

10. Error: PV Voltage Low (Error 103)

Cause: string voltage below the MPPT start window (60 V on MIN). Triggered by heavy panel shading, end-of-day low sun, or a partly disconnected string.

Fix: if morning/evening only, no action needed. If during full sun, check for a broken MC4 lead halving the string length, or a shaded panel pulling the string MPP voltage down.

11. Error: Over Temperature (Error 401 / "Inverter Overheat")

Cause: inverter heatsink exceeds 75 °C (residential) or 85 °C (commercial). Triggered by inadequate ventilation, west-facing wall mounting, or a clogged dust filter on MID/MAX commercial units.

Fix: check clearances — 50 cm above, 30 cm sides, 50 cm below on residential units. For MID/MAX, vacuum the dust filters. If the inverter is in direct sun, install a sun shade to drop ambient by 5–10 °C. The MAX 100-150KTL3-X derates linearly above 50 °C ambient — install in a ventilated shelter for full output.

12. Error: Fan Fault (Error 402)

Cause: one of the internal cooling fans is stalled. Often dust accumulation after 2–3 years of dusty-region operation (GCC, North Africa).

Fix: de-energise the inverter, open the fan access cover (model-specific), vacuum the blades, and verify free rotation. If a fan is seized, order a Growatt replacement kit — fans are field-serviceable on most residential models.

13. Error: Battery Fault (Error 601 / "BMS Comm Loss")

Cause: on hybrid SPH, MIN-XH, MID-XH: BMS communication cable between battery and inverter is broken or unseated.

Fix: check the BMS CAN cable — it must connect from the BAT-BOX BMS port to the inverter's BMS COM port (not "RS485" or "Parallel"). Reseat both ends. If reseating doesn't clear, swap the cable for a known-good one — bent RJ45 pins are common after a few service visits.

14. Error: Battery Reverse (Error 602)

Cause: battery cables wired with reversed polarity. The inverter refuses to connect to prevent damage.

Fix: de-energise everything, swap BAT+ and BAT− on the inverter terminals (or at the battery — both ends must match). Verify with a multimeter before re-energising.

15. Error: Battery OverVolt (Error 603)

Cause: battery DC voltage exceeds the inverter input range. Common after a non-Growatt battery with a different chemistry has been wired into an SPH or MIN-XH.

Fix: confirm the battery model is on the Growatt-approved list. Growatt ARK HV stacks (3.75–30 kWh) and APX HV 2.0 are the safe defaults. Lead-acid configuration requires a lower voltage profile — set via ShinePhone.

16. Error: Battery LowVolt (Error 604)

Cause: battery has discharged below the cutoff threshold. Often after a long grid outage with the inverter in EPS mode running a heavy load.

Fix: let the PV charge the battery during the next day, or temporarily allow grid AC charging (Battery → "AC Charge Enable" in ShinePhone). Raise the minimum SOC cutoff to 15–20% to prevent the same flat-battery event.

17. Error: Relay Check Fault (Error 414)

Cause: the inverter's internal AC contactor failed its self-test on startup.

Fix: power-cycle the inverter (AC off, DC off, wait 5 minutes, AC on, DC on). If the fault persists on three consecutive starts, the AC contactor needs replacement — return to Growatt service.

18. Warning: SPI Comm Fault (Warning 109)

Cause: internal SPI bus communication error between the MPPT controller and the main DSP. Non-fatal — the inverter continues running but logs a warning.

Fix: usually clears with a power-cycle. If the warning repeats, a firmware update via ShinePhone (Device Settings → Firmware Upgrade) clears it in 90% of cases.

When to Call Growatt Service vs Self-Service

• Self-service: PV Reverse, Grid Loss, Grid Volt/Freq Fault, PV Voltage Low/High, Battery Reverse, Fan Fault. All clear with simple field action.
• Investigate then call: ISO Error, GFCI Fault, Battery Fault, repeated BUS Voltage Fault, repeated Over Temperature.
• Service immediately: Relay Check Fault on repeat, internal capacitor errors (Fault 4XX), SPI Comm Fault that survives firmware update.

Filing a Growatt Warranty Claim

1. Export the event log from ShinePhone (last 30 days minimum).
2. Photograph the LCD showing the active fault.
3. Note inverter serial number (from the side label or under "About" in ShinePhone).
4. Send to your Growatt distributor with the install date and a brief description of the field checks already performed.
5. Most regional service desks respond within 24 business hours.