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7 Troubleshooting
※ 7.1 Fault Messages
Sunways STH 4~12kW series three-phase hybrid inverter is designed in accordance with
grid operation standard, and conform to the requirements of the safety and EMC. The in-
verter had passed a series of rigorous tests to ensure it runs sustainably and reliably before
shipment. When a fault occurs, the corresponding fault messages will display on the OLED
display, and in this case, the inverter might stop feeding into grid.
The fault messages and their corresponding troubleshooting methods are listed below:
7 Troubleshooting
Error Message
Description
Solution
Mains Lost
Grid power outage, AC switch or
circuit is disconnected.
① Check whether the mains supply is lost.
② Check whether the AC breaker and terminal are
well connected.
Grid Voltage Fault
Grid overvoltage or undervolt-
age, the grid voltage is higher
or lower than the set protection
value.
① Check whether the impendence of the
AC cable is too high to lead the grid voltage
increased. Change a thicker AC cable if it is.
② Extend the voltage protection range if it is al-
lowed by the electricity company.
Grid Frequency
Fault
Grid over frequency or under-
frequency, the grid frequency
is higher or lower than the set
protection value.
① Check whether the AC cable is correct and well
connected.
② Change to another country with wider protec-
tion range if it's allowed by the local electricity
company.
DCI Fault
DC injection High. Inverter de-
tects a higher DC component in
AC output.
① Restart the inverter.
② Seek for help from the installer or manufacture.
Error Message
Description
Solution
ISO Over Limita-
tion
Low system insulation resis-
tance, which is generally caused
by poor insulation to ground of
the module/cable or by rainy and
damp environment.
① Restart the inverter.
② Check if the insulation of the wires in PV, bat-
tery, and AC is damaged.
Seek for help from the installer or manufacture.
GFCI Fault
Excessive leakage current.
① Restart the inverter.
② Check if the insulation of the wires in PV, bat-
tery, and AC is damaged.
③ Seek for help from the installer or manufacture.
PV Over Voltage
PV over voltage is too high.
① Reduce the number of PV panels to make sure
the open-circuit voltage of each string is lower
than the inverter max allowed input voltage.
Bus Voltage Fault
BUS voltage is over-high.
① Check whether the input voltage is over the lim-
itation.
② Seek for help from the installer or manufacture.
Inverter Over Tem-
perature
Temperature anomaly, the tem-
perature of the interior of the
inverter is excessively high and
out of the safe range.
① Check if the heat dissipation of the inverter is
normal.
② Seek for help from the installer or manufacture.
SPI Fault
Internal communication fails.
Caused by a strong external
magnetic field etc.
① Restart the inverter.
② Seek for help from the installer or manufacture.
E2 Fault
Internal storage anomaly.
Caused by a strong external
magnetic field etc.
① Restart the inverter.
② Seek for help from the installer or manufacture.
7 Troubleshooting