The six kinds of inverter fault
Whatever the brand, a fault code points to one of six groups. Knowing the group tells you whether to wait, call an electrician, or call your installer.
| Group | Typical names on the screen | What to do first |
|---|---|---|
| Grid problem | Grid overvoltage, undervoltage, frequency fault, no grid, grid lost | Usually clears by itself when the grid recovers. If it repeats, have the grid voltage checked and talk to your electricity company |
| Insulation or earth fault | Low insulation resistance, isolation fault, leakage current, ground fault | Call a qualified technician: it can mean a damaged cable or a wet connector. On rainy mornings it can clear once panels dry |
| String or DC side | PV overvoltage, string reversed, string abnormal, PV string loss | Call a technician. DC wiring is dangerous; manufacturers say to wait until current is low and switch DC off before touching it |
| Overheating | Over temperature, ambient temperature high | Check ventilation and shade around the inverter; keep it out of direct sun |
| Communication | Meter communication fault, communication error, app shows offline | Usually not a production fault: check the meter cable or the Wi-Fi dongle and router |
| Device fault | Device abnormal, system fault, initialization fault | Switch AC and DC off, wait a few minutes, switch on. If it comes back, call service |
The same number means different things on each brand
People search for “fault 15”, “fault 52” or “fault 04” as if the numbers were universal. They are not. Read the brand and the exact text on the screen before you look anything up.
| Number | Sungrow | GoodWe (older units) | Growatt SPF (off-grid) |
|---|---|---|---|
| 03 | — | Grid frequency failure | Battery voltage too high |
| 04 | Grid undervoltage | — | Battery voltage too low |
| 15 | Grid overvoltage | Grid voltage failure | A warning, not a fault |
| 52 | — | — | Bus voltage too low |
Huawei (FusionSolar) alarm IDs
Huawei SUN2000 inverters show a 4-digit alarm ID with a name and a severity. On string alarms, the cause number tells you which PV input is affected.
- 2032 Grid Failed, 2033 Grid Undervoltage, 2034 Grid Overvoltage: grid problems.
- 2062 Low Insulation Resistance: insulation fault; the app can show where the short may be.
- 2001 String Voltage High, 2011 String Reverse Connection: DC-side wiring problems.
- 2013 String Power Abnormal and 2015 PV String Loss: a weak or lost string (Huawei is one of the few brands that flags this).
- 2063 Temperature High: overheating.
- 2064 Device Abnormal: internal fault; restart, then call service if it returns.
Growatt error and warning codes
Growatt uses different formats by series: grid-tied MIN, MOD and SPH units show “Error 2xx/3xx/4xx” and “Warning 2xx/4xx”; the large MAX series shows “Error 1xx”; SPF off-grid units show two-digit fault codes.
- Error 302 No AC connection, Error 300 AC voltage out of range, Error 304 AC frequency out of range: grid problems.
- Error 203 PV Isolation Low: insulation fault.
- Error 202 PV Voltage High: DC-side problem; switch DC off and have the strings measured.
- Warning 401 Meter communication abnormal: a communication fault, not a production fault.
- MAX series Warning 110 String abnormal: the only Growatt string alarm in the manuals we checked.
Solis, Sungrow and GoodWe
Solis shows short text alarms with a code, such as OV-G-V (grid overvoltage, 1010), NO-GRID (1015), PV ISO-PRO (insulation, 1033) and OV-TEM (over temperature, 1032). Sungrow shows numbers: 2, 3, 14 and 15 are grid overvoltage, 10 is a grid power outage, 39 is low insulation resistance, 37 is high ambient temperature, and a range of codes from 548 is the PV Abnormal Alarm, one code per string. Current GoodWe manuals show text messages, such as Utility Loss, Isolation Fail, PV Over Voltage and Over Temperature; older GoodWe units showed numbered errors.
The fault no code shows
In the manuals we checked, only Huawei, Sungrow and Growatt’s MAX series raise an alarm for a weak or dead string. Solis, GoodWe and Growatt’s MIN and SPH series do not. On those inverters a dead string simply produces nothing while the inverter keeps running on its other strings, the plant total looks normal, and no code appears.
That is the fault that costs owners most. Across the solar Wattey SPC monitors, 61% of inverters had a dead string or went silent within 60 days while the owner’s app still showed a working plant, and fixing a single dead string on a four-string inverter raised that inverter’s output by 31% over the next 8 days (as of 25 August 2026). Wattey SPC compares every string with its neighbours on any brand, so it finds the faults no code shows.
“Your inverter monitors. SPC inspects — string by string, across every brand — so a weak string can’t quietly bleed your output for months.”— Wattey Energy
