Hoymiles HM-250 User manual

Version 1.1 (June 2020)

© 2019 Hoymiles Converter Technology Co., Ltd. All rights reserved. 2
HM-250/HM-300/HM-350/HM-400
About Microinverter
This system is composed of a group of Microinverters that convert direct current (DC) into alternating
current (AC) and feeds it into the public grid. The system is designed for the incorporation of one
Microinverter for two photovoltaic modules. Each Microinverter works independently that guarantees the
maximum power generation of each photovoltaic module. This setup enables user to control the production
of a single photovoltaic module directly, consequently improving the flexibility and reliability of the system.
About the Manual
This manual contains important instructions for the HM-250/HM-300/HM-350/HM-400 Microinverter and
must be read in its entirety before installing or commissioning the equipment. For safety, only qualified
technician, who has received training or has demonstrated skills can install and maintain this Microinverter
under the guide of this document.
Other Information
Product information is subject to change without notice. User manual will be updated frequently, please
refer to Hoymiles official website at www.hoymiles.com for the latest version.

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HM-250/HM-300/HM-350/HM-400
Contents
1. Important Notes .................................................................................................................................................. 5
1.1 Product Range ............................................................................................................................................. 5
1.2 Target Group ................................................................................................................................................ 5
1.3 Symbols Used .............................................................................................................................................. 5
2. About Safety ........................................................................................................................
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2.1 Important Safety Instructions ..................................................................................................................... 5
2.2 Explanation of Symbols .............................................................................................................................. 6
2.3 Radio Interference Statement .................................................................................................................... 7
3. About Product ..................................................................................................................................................... 8
3.1 About Single Unit ......................................................................................................................................... 8
3.2 Highlights ...................................................................................................................................................... 8
3.3 Terminals Introduction ................................................................................................................................ 8
3.4 Dimension(mm) ............................................................................................................................................ 9
4. About Function ................................................................................................................................................... 9
4.1 Work Mode ................................................................................................................................................... 9
5. About Installation .............................................................................................................................................. 10
5.1 Accessories ................................................................................................................................................ 10
5.2 Installation Precaution ............................................................................................................................... 10
5.3 Space Distance Required ......................................................................................................................... 11
5.4 Preparation ................................................................................................................................................. 11
5.5 Installation Steps ....................................................................................................................................... 12
6. Troubleshooting ................................................................................................................................................ 16
6.1 Troubleshooting List .................................................................................................................................. 16
6.2 Status LED Indicator ................................................................................................................................. 19
6.3 On-site Inspection (For qualified installer only) ..................................................................................... 20
6.4 Routine Maintenance ................................................................................................................................ 20
6.5 Replace Microinverter ............................................................................................................................... 21
7. Decommissions ................................................................................................................................................ 22
7.1 Decommissions .......................................................................................................................................... 22
7.2 Storage and Transportation ..................................................................................................................... 22
7.3 Disposal ...................................................................................................................................................... 23
8. Compliance Consideration .............................................................................................................................. 23

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HM-250/HM-300/HM-350/HM-400
8.1 Earth Fault Alarm Notification .................................................................................................................. 23
8.2 Power Quality Response Modes ............................................................................................................. 23
8.3 DRM ............................................................................................................................................................. 23
9. Technical Data .................................................................................................................................................. 24
9.1 DC Input ...................................................................................................................................................... 25
9.2 AC Output ................................................................................................................................................... 25
9.3 Efficiency, Safety and Protection ............................................................................................................. 25
9.4 Mechanical Data ........................................................................................................................................ 25
9.5 Features ...................................................................................................................................................... 26
Appendix 1: ........................................................................................................................................................... 27
Installation Map ................................................................................................................................................ 27
Appendix 2: ........................................................................................................................................................... 28
WIRING DIAGRAM – 230VAC SINGLE PHASE: ....................................................................................... 28
WIRING DIAGRAM – 230VAC / 400VAC THREE PHASE: ....................................................................... 29

© 2019 Hoymiles Converter Technology Co., Ltd. All rights reserved. 5
HM-250/HM-300/HM-350/HM-400
1. Important Notes
1.1 Product Range
This manual describes the assembly, installation, commissioning, maintenance and failure search of
the following model of Hoymiles Microinverter:
l HM-250
l HM-300
l HM-350
l HM-400
*Note: “250” means 250W, “300” means 300W, “350” means 350W, “400” means 400W.
1.2 Target Group
This manual is only for qualified technician, who has been trained or has demonstrated skills can
install and maintain this Microinverter under the guide of this document for safety purpose.
1.3 Symbols Used
The safety symbols in this user manual are show as below.
2. About Safety
2.1 Important Safety Instructions
The HM-250/HM-300/HM-350/HM-400 Microinverter is designed and tested according to international
Symbol
Usage
Indicates a hazardous situation that can result in deadly electric shock
hazards, other serious physical injury, or fire hazards.
Indicates directions which must be fully understood and followed in
entirety in order to avoid potential safety hazards including equipment
damage or personal injury.
Indicates this points out that the described operation must not be carried
out. The reader should stop, use caution and fully understand the
operations explained before proceeding.

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HM-250/HM-300/HM-350/HM-400
safety requirements. However, certain safety precautions must be taken when installing and operating
this inverter. The installer must read and follow all instructions, cautions and warnings in this
installation manual.
Ø All operations including transport, installation, start-up and maintenance, must be carried out by
qualified, trained personnel.
Ø Before installation, check the unit to ensure free of any transport or handling damage, which could
affect insulation integrity or safety clearances. Choose installation location carefully and adhere to
specified cooling requirements. Unauthorized removal of necessary protections, improper use,
incorrect installation and operation may lead to serious safety and shock hazards or equipment
damage.
Ø Before connecting the Microinverter to the power distribution grid, contact the local power
distribution grid company to get appropriate approvals. This connection must be made only by qualified
technical personnel. It is the responsibility of the installer to provide external disconnect switches and
Over current Protection Devices (OCPD).
Ø Only one photo voltaic module can be connected to one input of the inverter. Do not connect
batteries or other sources of power supply. The inverter can be used only if all the technical
characteristics are observed and applied.
Ø Do not install the equipment in adverse environment conditions such as flammable, explosive,
corrosive, extreme high or low temperature, and humid. Do not use the equipment when the safety
devices do not work or disabled.
Ø Use personal protective equipment, including gloves and eye protection during the installation.
Ø Inform the manufacturer about non-standard installation conditions.
Ø Do not use the equipment if any operating anomalies are found. Avoid temporary repairs.
Ø All repairs should be carried out using only qualified spare parts, which must be installed in
accordance with their intended use and by a licensed contractor or authorized Hoymiles service
representative.
Ø Liabilities arising from commercial components are delegated to their respective manufacturers.
Ø Anytime the inverter has been disconnected from the public network, please be extremely caution
as some components can retain charge sufficient to create a shock hazard. Prior to touching any part
of the inverter please ensure surfaces and equipment are under touch safe temperatures and voltage
potentials before proceeding.
Ø Hoymiles accepts No liability for damage from incorrect or improper operation.
Ø Electrical Installation & Maintenance shall be conducted by licensed electrician and shall comply
with Local Wiring Rules.
2.2 Explanation of Symbols
Symbol
Usage
Treatment
To comply with European Directive 2002/96/EC on waste Electrical and
Electronic Equipment and its implementation as national law, electrical
equipment that has reached the end of its life must be collected separately and

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HM-250/HM-300/HM-350/HM-400
returned to an approved recycling facility. Any device no longer required must
be returned to an authorized dealer or approved collection and recycling facility.
Caution
Do not come within 8 inches (20cm) of the microinverter for any length of time
while it is in operation.
Danger of high voltages
Danger to life due to high voltage in the microinverter.
Beware of hot surface
The inverter can become hot during operation. Avoid contact with metal
surfaces during operation.
CE mark
The inverter complies with the requirements of the Low Voltage Directive for the
European Union.
Read manual first
Please read the installation manual first before installation, operation and
maintenance.
2.3 Radio Interference Statement
This microinverter has been tested and found to comply with the limits for CE EMC, which can provide
reasonable protection against harmful energy. However, if not installed according to the instructions,
the microinverter may cause harmful interference to radio equipment. There is no guarantee that the
interference will not occur in a particular installation.
To con fi rm that t he ra di o o r t el ev is io n r ec ep ti on is in te rf er ed by this equipment, you can turn the
equipment off and on. If this equipment does cause harmful interference to the radio or television
equipment, please try to correct the interference by one or more of the following measures:
1) Relocate the receiving antenna.
2) Increase the separation between the microinverter and the receiving antenna.
3) Place the shield between the microinverter and the receiving antenna, such as metal /
concrete roof.
4) Contact your dealer or an experienced radio/TV technician for help.

© 2019 Hoymiles Converter Technology Co., Ltd. All rights reserved. 8
HM-250/HM-300/HM-350/HM-400
3. About Product
3.1 About Single Unit
“The world’s First Daisy-Chain Single Unit Microinverter” with extremely wide DC input operating
voltage range (16-60V) and low start-up voltage (22V only).
Hoymiles Single unit Microinverter HM-250/HM-300/HM-350/HM-400 is the perfect selection for PV
system with uneven number of panels with world’s NO.1 CEC weighted efficiency – 96.50% (peak
efficiency 96.70%) in 2015.
3.2 Highlights
- Maximum output power up to 250W/300W/350W/400W; Adapted to 60 & 72 cells PV panels.
- Peak efficiency 96.70%; CEC weighted efficiency 96.50%.
- Static MPPT efficiency 99.80%; Dynamic MPPT efficiency 99.76% in overcast weather.
- Power factor (adjustable) 0.8 leading……0.8 lagging.
- External antenna for stronger communication with DTU.
- High reliability: NEMA6 (IP67) enclosure; 6000V surge protection.
3.3 Terminals Introduction
Object
Description
A
AC Connector (male)
B
AC Connector (Female)
C
DC Connectors

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HM-250/HM-300/HM-350/HM-400
3.4 Dimension(mm)
4. About Function
4.1 Work Mode
Normal: Under this mode, Microinverter is operating normally and convert DC power into AC power to
support the house loads and feed in to Public Grid.
Zero Export Control: Under this mode Microinverter’s generation is limit base on the current house
loads, there will be no extra power feed in to the Public Grid.
Stand by: There are several circumstance that Microinverter will stay in Standby mode:
- The current condition is contradicted with Microinverter operating requirement.
- No house loads or the Export control value has been set as “0” on the DTU under the Zero Export
Control mode.

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HM-250/HM-300/HM-350/HM-400
5. About Installation
5.1 Accessories
*Note: All accessories above are not included in the package, and need to be purchased separately. Please
contact our sales representative for the price. (M8 screws need to be prepared by installer-self.)
5.2 Installation Precaution
Please install the Microinverter and all DC connections under the PV module to avoiding direct sunlight,
rain exposure, snow layup, UV etc. Allow a minimum of 2 cm of space around the microinverter
enclosure to ensure ventilation and heat dissipation.
Object
Description
A
AC End Cable (Female), 2m 12AWG Cable
B
M8*25 screws
C
DC Extension Cable, 1m
D
AC Female End Cap, IP67

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HM-250/HM-300/HM-350/HM-400
*Note: For some countries the DTU will be required to meet the local grid regulation (e.g. G98/99 for UK
etc.)
5.3 Space Distance Required
If the microinverters are installed on a concrete roof or steel roof, the communication with the DTU
may be slightly affected. Under such installation conditions, it is better for the microinverters to be
installed 50cm above the roof. Otherwise, more DTUs may be required to ensure the communication
quality between the DTUs and the microinverters.
5.4 Preparation
Installation of the equipment is carried out based on the system design and the place in which the
equipment is installed.
The installation must be carried out with the equipment disconnected from the grid (power
disconnect switch open) and with the photovoltaic modules shaded or isolated.

© 2019 Hoymiles Converter Technology Co., Ltd. All rights reserved. 12
HM-250/HM-300/HM-350/HM-400
Referring to the Technical Data to make sure the environmental conditions fit the
microinverter’s requirement (degree of protection, temperature, humidity, altitude, etc.)
To avoi d powe r de-rating due to an increase in the microinverter internal temperature, do not
expose it to direct sunlight.
To av oi d ov er he at in g, a lw ay s make su re t he a ir f lo w ar ou nd t he i nv er ter is not blocke d.
Do not install in places where gasses or flammable substances may be present.
Avoid electromagnetic interference that can compromise the correct operation of electronic
equipment.
When choosing the position of installation, comply with the following conditions:
Install only on structures specifically conceived for photovoltaic modules (supplied by
installation technicians).
Install Microinverter underneath of the photovoltaic modules to make sure it works in
theshadow. If this condition cannot be met, might trigger the inverter production de-rating.
Fig.1 Installation position of microinverter
5.5 Installation Steps
Step 1. Fix Microinverter on the Rail
A) Mark the approximate center of each panel on the frame.
B) Fix the screw on the rail.
C) Hang the microinverter on the screw (shown as picture below), and tighten the screw. The silver
cover side of the microinverter should be facing the panel.

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HM-250/HM-300/HM-350/HM-400
*Note: Please install the microinverter at least 50cm above the ground/roof for better communication with
Hoymiles DTU.
Step 2. Connect AC Cables of Microinverter
A) Plug the AC connector of the first microinverter with the connector of the second microinverter, to
form a continuous AC branch circuit.
*Note: The length of AC cable on microinverter is around 1.23m. If the distance between two microinverters
is more than 1.21m, please use the AC extension cable between two inverters (As picture indicated below).
B) Install the AC end cap on the open AC connector of the last microinverter in the AC branch circuit.
Step 3. Connect AC End Cable
A) Make the end cable
1. Take the AC port apart into 3 parts:

© 2019 Hoymiles Converter Technology Co., Ltd. All rights reserved. 14
HM-250/HM-300/HM-350/HM-400
2. Insert the AC cable from Part 3 to Part 2, and complete the wiring for the L, N and Ground inside
Part 1 AC Port accordingly:
*Note: L: Brown wire N: Blue wire G: Yellow/Green wire
Please use 12 AWC cable as AC end cable
3. Plug the AC port Part 2 into Part 1 once complete the wiring, and screw the Part 3 on and complete
the AC extension cable:
B) Connect the AC End Cable to the AC Male connector from the first Microinverter to complete the
circuit.
C) Connect the other side of the AC End Cable to the distribution box, and wire it to the local grid
network.
Step 4. Create an Installation Map
A) Peel the removable serial number label from each microinverter (The position of the label is shown
as below.)

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HM-250/HM-300/HM-350/HM-400
B) Affix the serial number label to the respective location on the installation map.
Step 5. Connect PV Modules
A) Mount the PV modules above the microinverter.
B) Connect the PV modules’ DC cables to the DC input side of the microinverter.

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HM-250/HM-300/HM-350/HM-400
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.
Product information is subject to change without notice. (Please download reference manuals at
www.hoymiles.com.)
6. Troubleshooting
6.1 Troubleshooting List
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.
125
Grid configuration
parameter error
1.Check if the grid configuration parameter is correct and upgrade again.
2. If the fault still exists, contact your dealer or Hoymiles technical
support.
126
Software error code
126
1. If the alarm occurs accidentally and the microinverter can still work
normally, no special treatment is required.
2. If the alarm occurs frequently and cannot be recovered, contact your
dealer or Hoymiles technical support.
127
Firmware error
1.Check if the firmware is correct and upgrade again.
2.Check the communication between DTU and Hoymiles monitoring
system, the communication between DTU and microinverter. Then try
again.
3. If the fault still exists, contact your dealer or Hoymiles technical
support.
128
Software error code
128
1. If the alarm occurs accidentally and the microinverter can still work
normally, no special treatment is required.
2. If the alarm occurs frequently and cannot be recovered, contact your
dealer or Hoymiles technical support.

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HM-250/HM-300/HM-350/HM-400
129
Software error code
129
1. If the alarm occurs accidentally and the microinverter can still work
normally, no special treatment is required.
2. If the alarm occurs frequently and cannot be recovered, contact your
dealer or Hoymiles technical support.
130
Offline
1.Please make sure that the microinverter works normally.
2.Check the communication status between the DTU and hoymiles
monitoring system or between the DTU and the microinverter.If the
communication is poor, try to make some improvements.
3. If the alarm occurs frequently and cannot be recovered, contact your
dealer or Hoymiles technical support.
141
Grid overvoltage
1. If the alarm occurs accidentally, the grid voltage may be abnormal
temporarily. The microinverter can recover automatically after grid
voltage becomes normal.
2. If the alarm occurs frequently, check whether the grid voltage is within
the acceptable range. If no, contact the local power operator or change
the grid overvoltage protection limit via Hoymiles monitoring system with
the consent of the local power operator.
142
10 min value grid
overvoltage
1. If the alarm occurs accidentally, the grid voltage may be abnormal
temporarily. The microinverter can recover automatically after grid
voltage becomes normal.
2. If the alarm occurs frequently, check whether the grid voltage is within
the acceptable range. If no, contact the local power operator or change
the grid overvoltage protection limit via Hoymiles monitoring system with
the consent of the local power operator.
143
Grid undervoltage
1. If the alarm occurs accidentally, the grid voltage may be abnormal
temporarily. The microinverter can recover automatically after grid
voltage becomes normal.
2. If the alarm occurs frequently, check whether the grid voltage is within
the acceptable range. If no, contact the local power operator or change
the grid undervoltage protection limit via Hoymiles monitoring system
with the consent of the local power operator.
3. If the fault still exists, check the AC switch or AC wiring.
144
Grid overfrequency
1. If the alarm occurs accidentally, the grid frequency may be abnormal
temporarily. The microinverter can recover automatically after grid
frequency becomes normal.
2. If the alarm occurs frequently, check whether the grid frequency is
within the acceptable range. If no, contact the local power operator or
change the grid overfrequency protection limit via Hoymiles monitoring
system with the consent of the local power operator.
145
Grid underfrequency
1. If the alarm occurs accidentally, the grid frequency may be abnormal
temporarily. The microinverter can recover automatically after grid
frequency becomes normal.
2. If the alarm occurs frequently, check whether the grid frequency is
within the acceptable range. If no, contact the local power operator or

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HM-250/HM-300/HM-350/HM-400
change the grid underfrequency protection limit via Hoymiles monitoring
system with the consent of the local power operator.
146
Rapid grid frequency
change rate
1. If the alarm occurs accidentally, the grid frequency may be abnormal
temporarily. The microinverter can recover automatically after grid
frequency becomes normal.
2. If the alarm occurs frequently, check whether the grid frequency
change rate is within the acceptable range. If no, contact the local power
operator or change the grid frequency change rate limit via Hoymiles
monitoring system with the consent of the local power operator.
147
Power grid outage
Please check whether there is a power grid outage.
148
Grid disconnection
Please check whether the AC switch or AC wiring is normal.
149
Island detected
1. If the alarm occurs accidentally, the grid voltage may be abnormal
temporarily. The microinverter can recover automatically after grid
voltage becomes normal.
2. If the alarms occur frequently on all the microinverters in your station,
contact the local power operator to check whether there is a grid island.
3.If the alarm still exists, contact your dealer or Hoymiles technical
support.
205
Input port
overvoltage
1.Please make sure that the PV module open-circuit voltage is less than
or equal to the maximum input voltage.
2. If the PV module open-circuit voltage is within the normal range,
contact your dealer or Hoymiles technical support.
207
Input port
undervoltage
1.Please make sure that the PV module open-circuit voltage is less than
or equal to the maximum input voltage.
2. If the PV module open-circuit voltage is within the normal range,
contact your dealer or Hoymiles technical support.
209
Port No input
1. Please confirm whether this port is connected to the PV module;
2. If the PV module is connected, please check the DC cable connection
between this port and the PV module.
301
Hardware Error Code
301
1. If the alarm occurs accidentally and the microinverter can still work
normally, no special treatment is required.
2. If the alarm occurs frequently and cannot be recovered, contact your
dealer or Hoymiles technical support.
302
Hardware Error Code
302
1. If the alarm occurs accidentally and the microinverter can still work
normally, no special treatment is required.
2. If the alarm occurs frequently and cannot be recovered, contact your
dealer or Hoymiles technical support.
303
Hardware Error Code
303
1. If the alarm occurs accidentally and the microinverter can still work
normally, no special treatment is required.
2. If the alarm occurs frequently and cannot be recovered, contact your
dealer or Hoymiles technical support.
304
Hardware Error Code
304
1. If the alarm occurs accidentally and the microinverter can still work
normally, no special treatment is required.

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HM-250/HM-300/HM-350/HM-400
2. If the alarm occurs frequently and cannot be recovered, contact your
dealer or Hoymiles technical support.
305
Hardware Error Code
305
1. If the alarm occurs accidentally and the microinverter can still work
normally, no special treatment is required.
2. If the alarm occurs frequently and cannot be recovered, contact your
dealer or Hoymiles technical support.
306
Hardware Error Code
306
1. If the alarm occurs accidentally and the microinverter can still work
normally, no special treatment is required.
2. If the alarm occurs frequently and cannot be recovered, contact your
dealer or Hoymiles technical support.
307
Hardware Error Code
307
1. If the alarm occurs accidentally and the microinverter can still work
normally, no special treatment is required.
2. If the alarm occurs frequently and cannot be recovered, contact your
dealer or Hoymiles technical support.
308
Hardware Error Code
308
1. If the alarm occurs accidentally and the microinverter can still work
normally, no special treatment is required.
2. If the alarm occurs frequently and cannot be recovered, contact your
dealer or Hoymiles technical support.
6.2 Status LED Indicator
The LED flashes five times at start up. All green flashes (1s gap) indicate normal start up.
(1) Start-up Process
ü Flashing green five times (0.3s gap): Start-up success
ü Flashing Red five times (0.3s gap): Start-up failure
(2) Run Process
ü Flashing Fast Green (1s gap): Producing power.
ü Flashing Slow Green (2s gap): Producing power but one input is abnormal.
ü Flashing Slow Green (4s gap): Producing power but there is no communication with DTU.
ü Flashing Red (1s gap): Not producing power AC grid invalid (Voltage or frequency out of range).

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HM-250/HM-300/HM-350/HM-400
ü Flashing Red (0.5s gap): There is a fault except the abnormality of grid.
(3) Other Status
ü Flashing Red and Green alternately: Firmware is corrupted.
*Note: All the faults are reported to the DTU, refer to the local APP of the DTU or Hoymiles Monitoring Platform for more
information.
6.3 On-site Inspection (For qualified installer only)
To tr ou bl es ho ot a n in op er ab le microinver te r, follow t he s te ps i n th e order shown.
1. Verify the utility voltage and frequency are within ranges shown in the in appendix Technical Data
of this microinverter.
2. Check the connection to the utility grid. Verify utility power is present at the inverter in question by
removing AC, then DC power. Never disconnect the DC wires while the microinverter is producing
power. Re-connect the DC module connectors and watch for five short LED flashes.
3. Check the AC branch circuit interconnection between all the microinverters. Verify each inverter is
energized by the utility grid as described in the previous step.
4. Make sure that any AC breaker are functioning properly and are closed.
5. Check the DC connections between the microinverter and the PV module.
6. Verify the PV module DC voltage is within the allowable range shown in appendix Technical Data
of this manual.
7. If the problem persists, please call Hoymiles customer support.
Warning
Ø Do not try to repair the microinverter. 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
to report any anomalies.
2. Always use the personal protective equipment provided by the employer when carry out the
maintenance operation.
3. During normal operation, check that the environmental and logistic conditions are correct. Make sure