Refu sol 20K-2T User manual

REFUSOL 20K-2T
Installation and
operating manual
Version 01 | June 2023
English

REFUsol 20K-2T (853P020.200) User manual
REFUsol 20K-2T (853P020.200)
I
Table of Content
Preface ....................................................................................................................... III
1. Basic Safety Information .....................................................................................- 1 -
1.1. Requirement for Installation and Maintenance ................................ - 1 -
1.2. Symbols and signs .............................................................................. - 4 -
2. Product Characteristics .......................................................................................- 7 -
2.1. Intended Use ...................................................................................... - 7 -
2.2. Function Description ........................................................................- 11 -
2.3. Electrical block diagram ................................................................... - 12 -
2.4. Efficiency and derating curve ...........................................................- 12 -
3. Inverter Storage ................................................................................................- 14 -
4. Installation ........................................................................................................ - 15 -
4.1. Installation Process .......................................................................... - 15 -
4.2. Checking Before Installation ............................................................ - 15 -
4.3. Tools ..................................................................................................- 18 -
4.4. Determining the Installation Position ..............................................- 19 -
4.5. Moving of inverter ........................................................................... - 21 -
4.6. Installation ........................................................................................- 22 -
5. Electrical Connection ........................................................................................- 24 -
5.1. Electrical Connection ....................................................................... - 25 -
5.2. Grounding Connection (PE) ............................................................. - 25 -
5.3. Connect grid side of inverter (AC-Output) .......................................- 26 -
5.4. Connect PV side of inverter (DC-Input) ........................................... - 30 -
5.5. Communication Connection ............................................................ - 32 -
6. Commissioning of inverter ............................................................................... - 38 -
6.1. Cable Connection Inspection ........................................................... - 38 -
6.2. Start Inverter .................................................................................... - 38 -
7. Operation interface .......................................................................................... - 40 -
7.1. Operation and Display Panel ............................................................- 40 -
7.2. Standard Interface ............................................................................- 41 -
7.3. Main Interface ..................................................................................- 43 -
7.4. Updating Inverter Software ............................................................. - 51 -
8. Trouble shooting and maintenance ..................................................................- 54 -
8.1. Troubleshooting ............................................................................... - 54 -
8.2. Maintenance .................................................................................... - 66 -
8.3. Fan Maintenance ..............................................................................- 66 -
9. Technical Data ...................................................................................................- 68 -
10. Quality Assurance ...........................................................................................- 72 -

REFUsol 20K-2T (853P020.200) User manual
REFUsol 20K-2T (853P020.200)
II
Preface
Notice
The products, services or features you purchased shall be subject to the company's
commercial contracts and terms. All or part of the products and services described
in this document may not within the scope of your purchase. Unless additional
terms and conditions in your contract, the company does not make any statement
or guarantee on the contents of this document.
Save this Instruction
This manual must be considered as an integral part of the equipment. Customer
can print the electronic version to hard copy and keeping properly for future
reference. Anyone who operates the device at any time must operate in
accordance with the requirements of this manual.
Copyright Declaration
The copyright of this manual belongs to REFU Elektronik GmbH. Any corporation or
individual should not plagiarize, partially cope, or fully copy (including software,
etc.), not allow to duplication and publishment in any form and any way. All rights
reserved, REFU ELEKTRONIK reserves the right of final interpretation. This manual
subject to modify according to user's or customer's feedback. Please check our
website at http://www.refu.com for lasted version
Document Updates
V2.0 2023-2-23
REFU Elektronik GmbH
Marktstraße 185
72793 Pfullingen, GERMANY
www.refu.com/en/solar-solutions
Email：[e-mail]

REFUsol 20K-2T (853P020.200) User manual
REFUsol 20K-2T (853P020.200)
III
Outline
This manual is an integral part of REFUSOL 20K-2T (853P020.200). It describes the
assembly, installation, commissioning, maintenance and failure of the product.
Please read it carefully before operating.
Scope of Validity
This manual contains important instructions for REFUSOL 20K-2T (853P020.200).
Target Group
This manual is for qualified electricians. The tasks described in this manual only can
be performed by qualified electricians.
Symbols Used
The following types of safety instruction and general information appear in this
document as described below:
“Danger ”indicates a hazardous situation which, if not
avoided, will result in death or serious injury.
Danger
“Warning ”indicates a hazardous situation which, if not
avoided, could result in death or serious injury
Warning
“Caution ”indicates a hazardous situation which, if not
avoided, could result in minor or moderate injury
Caution
“Attention ”indicates there are potential risks, if fail to
prevent, may lead to equipment cannot normally or property
damage.
Attention
“Note ”provides additional information and tips that are
valuable for the optimal operation of the product.
Note

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1.Basic Safety Information
Outlines of this Chapter
Please read the instruction carefully. Faulty operation may cause serious injury or
death.
Safety Instruction
Introduce the safety instruction during installation and operation of REFUSOL
20K-2T (853P020.200)
Symbols Instruction
This section gives an explanation of all the symbols shown on the inverter and on
the type label.
1.1. Requirement for Installation and Maintenance
Installation of REFUSOL 20K-2T (853P020.200) on-grid inverter must conform with
laws, regulations, codes, and standards applicable in the jurisdiction.
Before installing and adjusting the produce, please read all of instructions, cautions
and warnings in this manual.
Before connecting the product to the electrical utility grid, contact the local utility
company for allowance. Also, this connection must be made only by qualified
electrician.
If the failure persists, please contact the nearest authorized maintenance center. If
you don't know which service center is closest to you, please contact your local
distributor. Don't repair the product by yourself, which may lead serious injury or
damage.
If you have any question or problem when you read the
following information, please contact REFU Elektronik GmbH.
Note

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Qualified Person
When inverter is working, it contains lethal voltages and went hot in some area.
Improper installation or maloperation could cause serial damage and injury. To
reduce the risk of personal injury and to ensure the safe installation and operation
of the product, only a qualified electrician is allowed to execute transportation,
installation, commissioning, and maintenance. REFU Elektronik GmbH does not
take any responsibility for the property destruction and personal injury because of
any incorrect use.
Label and Symbols
REFUSOL 20K-2T (853P020.200) has type label attach the side of product which
contact important information and technical data, the type label must permanent
attached to the product.
REFUSOL 20K-2T (853P020.200) has warming symbol attached the product which
contact information of safety operation. The warming symbol must permanent
attached to the product.
Installation location requirement
Please install the inverter according to the following section. Place inverter in an
appropriate bearing capacity object (such as solid brick wall, or strength equivalent
mounting surface, etc.) and make sure inverter vertical placed. A proper
installation location must have enough space for fire engine access for
maintenance if faulty occur. Ensure the inverter is installed in a wall ventilated
environment and have enough air-cooling cycle. Air humidity should less than 90%.

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Transportation Requirement
Inverter is in the good electrical and physical condition when it ship out from
factory. During transport, inverter must be placed in its original package or other
proper package. Transportation company should be responsible for any damage
during transport period.
If you find any packing problems that may cause the damage of inverter or any
visible damage, please notice the responsible transportation company immediately.
You can ask your installer or REFU ELEKTRONIK for help if necessary.
Electrical Connection
Please comply with all the current electrical regulations about accident prevention
in dealing with the current inverter.
Before the electrical connection, use opaque material to cover the
PV modules or disconnect PV string DC switch. PV arrays will
produce dangerous voltage if it is exposure under sun
Danger
All operation must accomplish by certified electrical engineer.
Must be trained.
Completely read the manual operation and understand all
information
Warming
Must get permission by local utility company before connecting to
grid and the connection must be done by certified electrical
engineers
Attention
Operation
Touching the utility grid or the terminal conductors can lead to
lethal electric shock or fire!
Do not touch non-insulated cable ends, DC conductors and any live
components of the inverter.
Attention to any electrical relevant instruction and document.
Danger
Enclosure or internal components may get hot during operation.
Do not touch hot surface or wear insulated gloves.
Attention

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Maintenance and repair
Before any repair work, turn OFF the AC circuit breaker between
the inverter and electrical grid first, then turn OFF the DC switch.
After turning OFF the AC circuit breaker and DC switch wait for at
least 5 minutes before carrying any maintenance or repair work.
Danger
Inverter should not work again until removing all faults. If any
repair work is required, please contact local authorized service
center.
Should not open the inverter cover without authorized permit,
REFU ELEKTRONIK does not take any responsibility for that.
Attention
EMC/Noise Level
Electromagnetic compatibility (EMC) refers to that on electrical equipment
functions in a given electromagnetic environment without any trouble or error and
impose no unacceptable effect upon the environment. Therefore, EMC represents
the quality characters of an electrical equipment.
The inherent noise-immune character: immunity to internal electrical noise
External noise immunity: immunity to electromagnetic noise of external
system
Noise emission level: influence of electromagnetic emission upon
environment
Electromagnetic radiation from inverter may be harmful to health!
Please do not continue to stay away from the inverter in less than
20cm when inverter is working
Danger
1.2. Symbols and signs
High voltage of inverter may be harmful to health!
Only certified engineer can operate the product.
Juveniles, Disable, should not use this product.
Keep this product out of the reach of children.
Danger
Caution of burn injuries due to hot enclosure!
Only touch the screen and pressing key of the inverter while it is
working
Caution

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PV array should be grounded in accordance to the requirements
of the local electrical grid company
Attention
Ensure the maximum DC voltage input is less than the maximum
inverter DC voltage (including in low temperature condition).
Any damage cause by overvoltage, REFU ELEKTRONIK will not
take the responsibility including warranty
Warning
Signs on the Product and on the Type Label
REFUSOL 20K-2T (853P020.200) has some safety symbols on the inverter. Please
read and fully understand the content of the symbols before installation.
Symbols
Name
Explanation
This is a residual voltage in
the inverter!
After disconnecting the DC side,
there is a residual voltage in the
inverter, operator should wait for 5
minutes to ensure the capacitor is
completely discharged.
Caution of high voltage and
electric shock
The products operate at high
voltages. Prior to performing any
work on the product, disconnect the
product from voltage sources. All
work on the product must be carried
out by qualified persons only.
Caution of hot surface
The product can get hot during
operation. Avoid contact during
operation. Prior to performing any
work on the product, allow the
product to cool down sufficiently
Comply with the
Conformity European (CE)
Certification
The product complies with the CE
Certification
Grounding Terminal
This symbol indicates the position
for the connections of an additional
equipment grounding conductor

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Observe the
documentation
Read all documentation supplied
with the product before install
Positive pole and negative
pole
Positive pole and negative pole of
the input voltage (DC)
Temperature
Indicated the temperature
allowance range
RCM logo
RCM (Regulatory Compliance Mark)
The product complies with the
requirements of the applicable
Australian standards.

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2.Product Characteristics
Outlines of this Chapter
Product Dimensions
Introduce the field of use and the dimensions of the product.
Function Description
Introduce working principle and internal components of the product.
Efficiency Curves
Introduce the efficiency curves of the product.
2.1. Intended Use
Field of use
REFUSOL 20K-2T (853P020.200) is a transformer-less on grid PV inverter, that
converters the direct current of the PV panels to the grid-compliant, three-phase
current and feeds into the utility grid.
Figure 2-1 PV Grid-Tied System
REFUSOL 20K-2T (853P020.200) may only be operated with PV arrays
(photovoltaic module and cabling) for on grid condition. Do not use this product
for any other or additional purposes. Any damage or property loss due to any use
of the product other than described in this section, REFU ELEKTRONIK will not take
the responsibility. DC input of the product must be PV module, other source such

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like DC sources, batteries will against the warranty condition and REFU
ELEKTRONIK will not take the responsibility.
Intended grid types.
REFUSOL 20K-2T (853P020.200) configurations. For the TT type of electricity
grid，the voltage between neutral and earth should be less than 30V. inverters are
compatible with TN-S, TN-C, TN-C-S, TT, IT grid.
Figure2-2: Overview of the grid configurations.
REFUsol Inverters
REFUsol Inverters
REFUsol Inverters
REFUsol Inverters
REFUsol Inverters

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Product Dimensions
The choice of optional parts of inverter should be made by a qualified
technician who knows the installation conditions clearly.
Dimensions Description
L×W×H=520*430*189mm
Figure 2-3 Front, side and back of the inverter
Figure 2-4a Bottom view
Note: REFUsol 20K-2T supports 4-channel PV string input.
Figure 2-5 bracket dimensions

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Function description of inverter box bottom
1. DC Switch
5. Breather valve
2. DC negative poles connecters
6. COM Port (for RS485
communication)
3. DC positive poles connecters
7. AC output
4. USB Port (for WIFI or Ethernet communication)
8. Fans
Figure 2-6 Bottom view of the REFUSOL 20K-2T (853P020.200)
Labels on the equipment
Note: label must NOT be hidden with objects and extraneous parts (rags, boxes, equipment,
etc.,); they must be cleaned regularly and always kept visible.
Figure 2-7 Product label
8
1 2 3 4 5 6 7

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2.2. Function Description
DC power generated by PV arrays is filtered through Input Board then enter Power
Board. Input Board also offer functions such as insulation impedance detection and
input DC voltage/ current detection. DC power is converted to AC power by Power
Board. AC power is filtered through Output Board then AC power is fed into the
grid. Output Board also offer functions such as grid voltage/ output current
detection, GFCI and output isolation relay. Control Board provides the auxiliary
power, controls the operation state of inverter, and shows the operation status by
Display Board. Display Board displays fault code when inverter is abnormal
operation conditions. At the same time, Control Board can trigger the replay to
protect the internal components.
Function Module
A. Energy management unit
Remote control to start/ shunt down inverter through an external control.
B. Feeding reactive power into the grid
The inverter can produce reactive power thus to feed it into the grid through
the setting of the phase shift factor. Feed-in management can be controlled
directly by APP or through a RS485 interface.
C. Limited the active power fed into grid.
If enable the limited of active power function, inverter can limit the amount of
active power fed into the grid to the desired value (expressed as percentage)
D. Self-power reduction when grid is over frequency.
If grid frequency is higher than the limited value, inverter will reduce the
output power to ensure the grid stability.
E. Data transmission
Inverter or a group of inverters can be monitored remotely through an
advanced communication system based on RS485 interface or via USB port.
F. Software update
USB interface for uploading the firmware, remotely uploading by using USB
acquisition stick (WIFI or Ethernet) is also available.

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2.3. Electrical block diagram
Figure 2-8 Schematic diagram
2.4. Efficiency and derating curve
Figure 2-9 Power efficiency curve

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Figure 2-10 Rated Power ratio vs Grid Voltage

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3.Inverter Storage
If inverter is not installed immediately, storage condition need to meet below
requirements:
Place inverter into the original package and leave desiccant inside, sealed
tight with taps.
Keep the storage temperature around -40℃～70℃, Relative humidity 0 ～
95%, no condensation.
Figure 3-1 Storage temperature and humidity
The maximum stacking layer number cannot exceed 4 layers.
If the inverter be storage for more than half years, the inverter needs to be
fully examined and tested by qualified service or technical personnel before
using.

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4.Installation
Outlines of this Chapter
This topic describes how to install this product, please read carefully before install.
Do NOT install the product on flammable material.
Do NOT store this product in potentially explosive
atmospheres
Dangers
The enclosure and heat sink will get hot during operation,
please do not mount the product at a easy to reach location
Caution
Consider the weight of this product when doing transport
and moving.
Choose an appropriate mounting position and surface.
At least two persons for installation
Attention
4.1. Installation Process
4.2. Checking Before Installation
Checking Outer Packing Materials
Before unpacking, please check the condition of the outer package materials if any
damaged found, such as holes, cracks, please not unpack the product, contact your
distributor immediately. Recommend installing the product within 24 hours after
unpacking the package.