© 2019 Hoymiles Power Electronics Inc. All rights reserved.
16
MI-300N/MI-350N/MI-400N
Step 6. Energize the System
A) Turn on the AC breaker of the branch circuit.
B) Turn on the main AC breaker of the house. Your system will start to generate power after about
two-minute wait time.
Step 7. Set Up the Monitoring System
Refer to the DTU User Manual or DTU Quick Install Guide, and Quick Installation Guide for HMP
Online Registration to install the DTU and set up your monitoring system.
6. Troubleshooting
Hoymiles updated the interactive performance of the microinverter system in the middle of 2020. If
you use the microinverter of serial number “1022xxxxxxxx”, please refer to chapter 6.1 and chapter
6.3. If you use the microinverter of serial number “1020xxxxxxxx” and “1021xxxxxxxx”, please refer to
chapter 6.2 and chapter 6.4.
*Note: The microinverter of serial number “1062xxxxxxxx” can only work with the new Hoymiles gateway, DTU-Pro
(SN: 10F7xxxxxxxx, 10F8xxxxxxxx), DTU-G100 (SN: 10D2xxxxxxxx) and DTU-W100 (SN: 10D3xxxxxxxx).
6.1 Troubleshooting List (SN: 1022xxxxxxxx)
Alarm
Code
Alarm Name
Suggestion
121
Over temperature
protection
1. Check the ventilation and ambient temperature at the microinverter
installation position.
2. If the ventilation is poor or the ambient temperature exceeds the limit,
improve the ventilation and heat dissipation.
3. If both the ventilation and ambient temperature meet the
requirements, contact your dealer or Hoymiles technical support.