GoodWe Inverter VAC Fail: Troubleshooting and Fixes

Key Takeaways

• A VAC Fail error means the grid AC voltage is outside the inverter's acceptable range.
• Always check for grid power availability and the status of your AC breaker first.
• Before touching any internal components, disconnect all power sources and wait at least 5 minutes.
• If the fault persists after basic checks and restarts, contact a qualified service technician.

What does a GoodWe VAC Fail error mean?

A GoodWe inverter displaying a VAC Fail error signifies that the inverter detects the AC voltage from the utility grid is beyond the normal operating range required by the safety country. This condition prevents the inverter from connecting to or feeding power into the grid. The most common cause is an issue with the grid connection itself, such as a power outage or incorrect AC wiring.

The first step in troubleshooting is to verify grid power availability and inspect all AC connections and breakers.

IMPORTANT SAFETY WARNING: GoodWe inverters operate at high voltages. All physical inspections, checks, and interventions described below must only be performed by qualified electricians who have read and understood the 'Safety: Working with GoodWe Inverters' section of this article and the inverter's official manual. Failure to do so can result in severe injury or death, and may void your warranty.

Diagnosing a GoodWe VAC Fail

Follow these steps to diagnose the cause of a VAC Fail error on your GoodWe inverter:

1. Check Grid Power Availability:

• • Action: Look for power in your home or facility. Check if other appliances are working or if neighbours have power.
  • Meaning: If there is a general power outage, the inverter cannot detect a stable grid voltage and will report a VAC Fail or Utility Loss.

2. Inspect the AC Breaker:

• • Action: Locate the AC breaker connected to your inverter. Ensure it is in the "on" position.
  • Meaning: A tripped AC breaker will cut off the inverter's connection to the grid, leading to a VAC Fail or Utility Loss (Code 09). Reset the breaker if it is tripped.

3. Examine AC Wiring and Connections:

• • Action: Visually inspect all AC cables connected to the inverter and the main electrical panel. Look for any loose, damaged, or corroded connections.
  • Meaning: Loose or faulty wiring can cause intermittent or incorrect voltage readings, triggering a VAC Fail. Ensure all connections are tight.

4. Verify Inverter Display or App for Specific Codes:

• • Action: Check the inverter's display screen or the GoodWe PV Master/SolarGo app for specific error codes.
  • Meaning: While "VAC Fail" is a general symptom, specific codes like 23 ("Vac Consistency Failure"), 09 ("Utility Loss"), 17 ("ac Failure"), or 29 ("FAC Failure") provide more precise information about the fault.

5. Perform an Inverter Restart:

• • Action: If the grid is active and connections appear secure, try restarting the inverter. First, turn off the AC breaker, then any DC isolators (PV and battery). Wait for 5 minutes for internal capacitors to safely discharge, then turn them back on in reverse order (DC, then AC).
  • Meaning: A simple restart can sometimes clear temporary communication glitches or minor inconsistencies that trigger a VAC Fail.

WARNING: All physical checks and interventions in this table involve high voltage and must only be performed by qualified electricians after consulting the 'Safety: Working with GoodWe Inverters' section and the inverter's manual. Ensure all power sources are disconnected and wait 5 minutes for capacitor discharge before touching any components. Unauthorized modifications may void your warranty.

Cause and Fix Table for GoodWe VAC Fail

Inverter-Side vs. Grid-Side Checks

When troubleshooting a VAC Fail, it is important to distinguish between issues originating from the utility grid and those within your inverter system.

Grid-Side Checks: These checks focus on the quality and presence of the AC power supplied by your utility.

• Grid Power Availability: Confirm that there is no general power outage in your area.
• AC Breaker Status: Ensure the main AC breaker for your inverter is not tripped. An external AC breaker is needed for on-grid connection to isolate the inverter from the utility grid. Absence of an AC breaker will lead to inverter damage if an electrical short circuit happens on the grid side.
• AC Cable Integrity: Verify that all AC cables connecting your inverter to the grid are securely fastened and free from damage.
• Grid Voltage and Frequency: While you may not have tools to measure these precisely, the inverter's display or monitoring app (PV Master or SolarGo) will often indicate if voltage or frequency is out of range, leading to errors like "VAC Failure" or "FAC Failure".

Inverter-Side Checks: These checks focus on the inverter's internal components and settings.

• Error Codes: Pay attention to specific error codes displayed. Codes like 23 ("Vac Consistency Failure"), 06 ("GFCI - Consistency Failure Device check failure"), or 22 ("Fac Consistency Failure") often point to internal inverter issues that may require professional attention.
• Firmware: Ensure your inverter's firmware is up to date. While not a direct fix for VAC Fail, outdated firmware can sometimes lead to stability issues.
• Restart Procedure: A controlled restart of the inverter can resolve transient internal faults.

Safety: Working with GoodWe Inverters

Always prioritize safety when working with solar inverters. GoodWe inverters, like the ET, A-ES, and ES series, operate at high voltages.

• Qualified Personnel Only: Installation, operation, and maintenance must be performed by qualified electricians.
• High Voltage/Electric Shock: There is a danger of high voltage and electric shock. Always wait at least 5 minutes after disconnecting all power (PV, battery, and AC) before touching internal parts. This allows internal capacitors to discharge.
• Hot Surface: The inverter surface can exceed 60℃ during operation. Ensure it has cooled down before touching.
• Unauthorized Modifications: Do not open the inverter cover or change components without the manufacturer's authorization, otherwise the warranty is invalid.
• Disconnect All Power: Before any inspection or work on AC connections, ensure the AC breaker is off, and all DC power sources (PV and battery) are disconnected.

When to call a technician instead

While basic troubleshooting can resolve many issues, certain situations require professional intervention to ensure safety and proper system function. You should call a qualified technician if:

• The VAC Fail error persists after you have performed all the recommended basic checks and restarts.
• The inverter displays internal consistency failure codes such as Code 23 ("Vac Consistency Failure"), Code 06 ("GFCI - Consistency Failure Device check failure"), or Code 22 ("Fac Consistency Failure"). These often indicate an internal hardware fault.
• You are unsure about checking electrical connections or feel uncomfortable working with high voltage.
• The issue is intermittent and difficult to diagnose.
• Any physical damage is observed on the inverter or its wiring.

Attempting unauthorized repairs or modifications can void your warranty. GoodWe states that unauthorized modifications will invalidate the warranty. For issues beyond simple external checks, contacting a GoodWe authorized service centre is the safest and most effective course of action.