Understanding Error Codes
When your inverter encounters an issue, it displays an error code to help diagnose the problem. Some errors are temporary and resolve on their own, while others require professional attention. Below are the most common codes you might encounter.
Before You Panic
Many error codes are caused by temporary grid conditions or weather events and clear automatically. If you see an error code, note it down and check again after 30 minutes. If it persists, try a power cycle before calling for help.
Fronius Error Codes
Fronius calls them state codes, and the first digit tells you most of what you need to know. That is the thing worth learning, because there are hundreds of individual codes and only five families.
| First digit | What it means | Do you need to do anything? |
|---|---|---|
| 1xx | The grid is outside the range your inverter is allowed to work in. Voltage or frequency, and it is the network's side, not yours. | Usually no. It reconnects by itself. Tell us if it is constant. |
| 2xx | Messages from the grid-monitoring device built into the inverter, again about the public mains. | Usually no. |
| 3xx | Status during feed-in. Not damage, but the inverter may drop off the grid for a while. | Often no, but 3xx codes that stay are worth a call. |
| 4xx | A hardware or software fault inside the inverter. | Yes. These need a technician. |
| 5xx | Information and warnings. Production usually continues. The message sits on the screen until you acknowledge it. | Read it, then decide. |
1xx: the grid, not your system
These are the most common codes in Australia by a wide margin, and they are the ones people most often mistake for a broken inverter.
State 102: AC voltage too high.
The grid voltage where you live has gone above the range the inverter is
permitted to feed into, so it stops and waits. This is a network condition. It
is very common in parts of South East Queensland, especially in the middle of
the day in streets with a lot of solar.
State 103: AC voltage too low.
The reverse, and usually a local grid event that clears on its own.
State 105: AC frequency too high.
Again the network's side. The inverter is required to disconnect.
If 102 keeps coming back
Repeated 102s are worth reporting to Energex, because the fix is on their side of the meter. Note the times of day it happens before you call them, and if you would rather we did it, get in touch and we will look at your production data first.
3xx: feed-in states
State 301: Overcurrent (AC).
An AC current peak on the grid side. Usually clears after a restart.
State 302: Overcurrent (DC).
Too much current coming in from the panels.
State 306: PV power low.
The intermediate circuit voltage is too low to feed the grid. Normal at dawn
and dusk. Not normal at midday.
State 307: DC input voltage too low.
Same family as 306, same reasoning.
4xx: these need a technician
State 401: Communication fault.
The inverter's control board has lost internal communication with its power
stage. This is not something to keep resetting.
State 407: Heat sink temperature sensor faulty.
A failed sensor rather than an overheating inverter, but it still needs
attention.
State 443: Intermediate circuit voltage too low or asymmetric.
State 475: Insulation fault (PE conductor).
Safety-critical, and the same family as the isolation faults below.
State 502: Isolation fault (DC).
The inverter has detected a potential earth fault in the DC wiring.
Isolation and insulation faults: do not ignore
State 475 and State 502 can both mean damaged wiring or moisture getting in. Do not reset the inverter repeatedly to clear them. Book a professional inspection.
5xx: warnings
State 509: No feed-in for 24 hours.
The inverter has produced nothing for a full day. Sometimes that is heavy
soiling or shading. Often it is a genuine fault that has been sitting there
unnoticed, which is exactly why this code exists.
State 522 and 523: DC input voltage too low.
State 516: No grid connection.
The inverter cannot see the grid at all. Check your switchboard for a tripped
breaker. If the power is out in your street, this is expected.
This list is not complete
Fronius publishes hundreds of state codes and this covers the ones we see most often on Brisbane roofs. If your code is not here, it does not mean it is serious, and it does not mean it is not. Note the number and send it to us.
Sungrow Error Codes
Common Fault Codes
Fault 001: Grid Over-Voltage.
Grid voltage exceeds limits. The inverter will reconnect automatically when voltage returns to normal. If frequent, report to Energex.
Fault 002: Grid Under-Voltage.
Grid voltage too low. Usually temporary and self-resolving.
Fault 003: Grid Over-Frequency.
Grid frequency is above 50.25Hz. A temporary grid condition that resolves automatically.
Fault 009: No Utility (Grid Lost).
Grid connection lost. Check for local power outages and tripped breakers.
Fault 014: Isolation Resistance Low.
Similar to Fronius Error 502: a potential earth fault in the DC system. Requires professional inspection.
Fault 039: Inverter Over-Temperature.
The inverter has shut down to prevent heat damage. Ensure adequate ventilation around the inverter. It will restart once it cools down.
Keep a Log
If you're seeing recurring error codes, keep a simple log: date, time, error code, and weather conditions. This information is invaluable for your installer when diagnosing intermittent issues.
When to Call Your Installer
Self-resolving (wait and monitor):
- Grid voltage and frequency codes: Fronius 102, 103 and 105, and Sungrow Fault 001 to 003
- Over-temperature warnings on very hot days
- Fronius 306 and 307 first thing in the morning and last thing at night
Power cycle then monitor:
- Fronius 301 (AC overcurrent): if it comes back after a restart, call us, as it may indicate a wiring issue
- Communication errors
- Startup sequence codes that have not cleared by mid-morning
Call immediately:
- Isolation and insulation faults: Fronius 475 and 502, Sungrow Fault 014
- Anything in the Fronius 4xx family, which means a fault inside the inverter
- Fronius 509, which means a full day with no production at all
- Persistent codes that do not clear after a power cycle
- Any code accompanied by unusual smells, sounds, or visible damage
For all UV Power installations, call 1300 887 140 or email admin@uvpower.com.au with the error code and a photo of the display. We can often diagnose the issue remotely.
