© 2022 Hoymiles Power Electronics Inc. All rights reserved.
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Single-phase Microinverter HMS-350/400/450/500-1T-NA
6.3 On-site Inspection (For qualified installer only)
Troubleshoot a malfunctioning microinverter according to the following steps.
1
Check if the utility voltage and frequency are within the respective range shown in Technical Data
section of this manual.
2
Check the connection to the utility grid.
Disconnect the AC and the DC power. Please note that when the inverter is in operation, disconnect
the AC power first to de-energize the inverter, and then disconnect the DC power.
Re-connect the PV modules to the microinverter. LED will flash red to indicate normal DC connection.
Re-connect the AC power. LED will flash green for five times to indicate normal DC and AC connection.
Never disconnect the DC wires while the microinverter is producing power. Re-connect the DC
module connectors and wait for five short LED flashes.
3
Check the interconnection between all the microinverters on the AC branch circuit. Confirm that
each inverter is energized by the utility grid as described in the previous step.
4
Make sure that every AC breaker is functioning properly and is closed.
5
Check the DC connection between the microinverter and the PV module.
6
Make sure that PV modules’ DC voltage is within the allowable range shown in the Technical Data
section of this manual.
7
If the problem persists, please call Hoymiles customer support.
Do not try to repair the microinverter by yourself. If the troubleshooting fails, please return it to
the factory for replacement.
6.4 Routine Maintenance
1. Only authorized personnel are allowed to carry out the maintenance operations and are responsible for
reporting any anomalies.
2. Always use personal protective equipment provided by the employer during maintenance operation.
3. During normal operation, check the environmental conditions regularly to make sure that the conditions
have not changed over time and that the equipment is not exposed to adverse weather conditions and has
not been obstructed.
4. DO NOT use the equipment if any problems are detected. Restore its working conditions after the fault is
fixed.
5. Conduct annual inspections on various components, and clean the equipment with a vacuum cleaner or
special brushes.
Do not attempt to dismantle or repair the microinverter! No user-serviceable parts inside for the
safety and insulation reasons!
The AC output wiring harness (AC drop cable on the microinverter) cannot be replaced. The
equipment should be scrapped if the cord is damaged.
Maintenance operations must be carried out with the equipment disconnected from the grid (power
switch open) and the PV modules shaded or isolated, unless otherwise indicated.
Never clean the equipment with rags made of filamentary or corrosive materials to avoid corrosion
and electrostatic charges.
Do not attempt to repair the product. All repairs should be done using only eligible spare parts.
If all the microinverters are connected to the DTU-Pro-S, the DTU can limit the output power
imbalance of all the microinverters between phases to below 3.68 kW if required. Please refer to
“Hoymiles Technical Note Limit Phase Balance” for more details.
