SMA SUNNY ISLAND 6.0H User guide

SI44M-80H-13-MC-IA-en-10 | Version 1.0ENGLISH
System Description
Multicluster Systems with Stand-Alone Grid or
Increased Self-Consumption and Battery-Backup
Function
SunnyIsland 6.0H / 8.0H and Multicluster-Box 12 / Grid-Connect-Box 12

Legal Provisions SMA Solar Technology AG
System DescriptionSI44M-80H-13-MC-IA-en-102
Legal Provisions
The information contained in these documents is the property of SMA Solar Technology AG. No part of this document
may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, be it electronic,
mechanical, photographic, magnetic or otherwise, without the prior written permission of SMA Solar Technology AG.
Internal reproduction used solely for the purpose of product evaluation or other proper use is allowed and does not
require prior approval.
SMA Solar Technology AG makes no representations or warranties, express or implied, with respect to this
documentation or any of the equipment and/or software it may describe, including (with no limitation) any implied
warranties of utility, merchantability, or fitness for any particular purpose. All such representations or warranties are
expressly disclaimed. Neither SMA Solar Technology AG nor its distributors or dealers shall be liable for any indirect,
incidental, or consequential damages under any circumstances.
The exclusion of implied warranties may not apply in all cases under some statutes, and thus the above exclusion may
not apply.
Specifications are subject to change without notice. Every attempt has been made to make this document complete,
accurate and up-to-date. Readers are cautioned, however, that product improvements and field usage experience may
cause SMA Solar Technology AG to make changes to these specifications without advance notice, or per contract
provisions in those cases where a supply agreement requires advance notice. SMA Solar Technology AG shall not be
responsible for any damages, including indirect, incidental or consequential damages, caused by reliance on the
material presented, including, but not limited to, omissions, typographical errors, arithmetical errors or listing errors in
the content material.
SMA Warranty
You can download the current warranty conditions from the Internet at www.SMA-Solar.com.
Trademarks
All trademarks are recognized, even if not explicitly identified as such. Missing designations do not mean that a
product or brand is not a registered trademark.
SMA Solar Technology AG
Sonnenallee 1
34266 Niestetal
Germany
Tel. [phone]
Fax [phone]
www.SMA.de
Email: [email protected]
Status: 9/12/2019
Copyright © 2019 SMA Solar Technology AG. All rights reserved.

Table of Contents
SMA Solar Technology AG
System Description 3SI44M-80H-13-MC-IA-en-10
Table of Contents
1 Information on this Document..................................................................................................... 4
1.1 Validity ............................................................................................................................................................. 4
1.2 Target Group ................................................................................................................................................... 4
1.3 Content and Structure of this Document......................................................................................................... 4
1.4 Levels of Warning Messages.......................................................................................................................... 4
1.5 Symbols in the Document................................................................................................................................ 5
1.6 Typographies in the Document....................................................................................................................... 5
1.7 Designation in the document .......................................................................................................................... 5
1.8 Additional Information..................................................................................................................................... 6
2 Safety ............................................................................................................................................ 7
2.1 Intended Use.................................................................................................................................................... 7
2.2 IMPORTANT SAFETY INSTRUCTIONS......................................................................................................... 8
2.3 Battery Safety Information............................................................................................................................... 11
3 Functions and Design................................................................................................................... 14
3.1 Design of a Multicluster-Box ........................................................................................................................... 14
3.2 Structures of a Multicluster System................................................................................................................. 15
3.2.1 Structures for Off-Grid Systems ....................................................................................................................... 15
3.2.2 Structure for Systems with Increased Self-Consumption and Battery-Backup Function................................ 17
3.3 Off-Grid System............................................................................................................................................... 17
3.3.1 Off-Grid System Functions............................................................................................................................... 17
3.3.2 Off-Grid System Requirements ........................................................................................................................ 18
3.3.3 Optional Devices and Functions ..................................................................................................................... 18
3.4 Multicluster System with Increased Self-Consumption and Battery-Backup Function.................................. 19
3.4.1 Principle of a System with Increased Self-Consumption and Battery-Backup Function................................ 19
3.4.2 Requirements of VDE Application Guide 2510-2.......................................................................................... 20
3.4.3 Requirements for Systems with Increased Self-Consumption and Battery-Backup Function........................ 20
4 Circuitry of Multicluster Systems ................................................................................................. 21
4.1 Connecting the Master in the Main Cluster................................................................................................... 21
4.2 Connecting Slave 1 in the Main Cluster ........................................................................................................ 23
4.3 Connecting Slave 2 in the Main Cluster ........................................................................................................ 25
4.4 Connecting the Sunny Island Inverters in Extension Clusters........................................................................ 26
5 Commissioning ............................................................................................................................. 27
5.1 Commissioning Procedure............................................................................................................................... 27
5.1.1 Commissioning Procedure for an Off-Grid System ........................................................................................ 27
5.1.2 Procedure when Commissioning a System with Increased Self-Consumption and Battery-Backup
Function............................................................................................................................................................. 28
5.2 Testing Communication in the Multicluster System........................................................................................ 29
5.3 Commissioning an Off-Grid System ............................................................................................................... 30
5.3.1 Commissioning the Multifunction Relays ........................................................................................................ 30
5.3.2 Testing the Load Shedding .............................................................................................................................. 30
5.4 Commissioning a System With Increased Self-Consumption and Battery-Backup Function ....................... 30
5.4.1 Adjusting the Configuration of the Sunny Island............................................................................................ 30
5.4.2 Adjusting the Configuration of the PV Inverters.............................................................................................. 31
5.4.3 Commissioning the System with Increased Self-Consumption and Battery-Backup Function...................... 31
5.4.4 Registering the Multicluster System in Sunny Portal....................................................................................... 32
6 Contact .......................................................................................................................................... 33

1 Information on this Document SMA Solar Technology AG
System DescriptionSI44M-80H-13-MC-IA-en-104
1 Information on this Document
1.1 Validity
This document is valid for multicluster systems with stand-alone grid or increased self-consumption and battery-backup
function, in which the following device types are used:
• SI6.0H-13 (SunnyIsland 6.0H) from firmware version 1.04.xx.R
• SI8.0H-13 (SunnyIsland 8.0H) from firmware version 1.04.xx.R
• MC-BOX-12.3-20 (Multicluster-Box 12)
• GRID-BOX-12.3-20 (Grid-Connect-Box 12)
1.2 Target Group
The tasks described in this document must only be performed by qualified persons. Qualified persons must have the
following skills:
• Knowledge of how an inverter works and is operated
• Knowledge of how batteries work and are operated
• Training in the installation and commissioning of electrical devices and installations
• Knowledge of all applicable laws, standards and directives
• Knowledge of and compliance with this document and all safety information
• Knowledge of and compliance with the documents of the battery manufacturer with all safety information
1.3 Content and Structure of this Document
This document summarizes the specific information on multicluster systems with SunnyIsland inverters and Multicluster-
Box12. The structure of the document specifies the chronological sequence for configuration and commissioning.
This document supplements the documents that are enclosed with each product and does not replace any locally
applicable codes or standards. Read and observe all documents supplied with the product.
Illustrations in this document are reduced to the essential information and may deviate from the real product.
1.4 Levels of Warning Messages
The following levels of warning messages may occur when handling the product.
DANGER
Indicates a hazardous situation which, if not avoided, will result in death or serious injury.
WARNING
Indicates a hazardous situation which, if not avoided, could result in death or serious injury.
CAUTION
Indicates a hazardous situation which, if not avoided, could result in minor or moderate injury.
NOTICE
Indicates a situation which, if not avoided, can result in property damage.

1 Information on this Document
SMA Solar Technology AG
System Description 5SI44M-80H-13-MC-IA-en-10
1.5 Symbols in the Document
Symbol Explanation
Information that is important for a specific topic or goal, but is not safety-relevant
☐
Indicates a requirement for meeting a specific goal
☑
Desired result
✖
A problem that might occur
Example
This information is relevant for systems which are to be operated in parallel with utility grid.
(e.g. SMAFlexibleStorageSystem).
Content is relevant for off-grid systems.
Section in which the installation and commissioning process is illustrated graphically.
1.6 Typographies in the Document
Typography Use Example
bold • Messages
• Terminals
• Elements on a user interface
• Elements to be selected
• Elements to be entered
• Connect the insulated conductors
to the terminals X703:1 to
X703:6.
• Enter 10 in the field Minutes.
>• Connects several elements to be
selected • Select Settings > Date.
[Button]
[Key]
• Button or key to be selected or pressed • Select [Enter].
# • Placeholder for variable components
(e.g., parameter names) • Parameter WCtlHz.Hz#
1.7 Designation in the document
Complete designation Designation in this document
Grid-Connect-Box 12 Grid-Connect-Box
Multicluster-Box 12 Multicluster-Box

1 Information on this Document SMA Solar Technology AG
System DescriptionSI44M-80H-13-MC-IA-en-106
Complete designation Designation in this document
Multicluster system with increased self-consumption, bat-
tery-backup function or increased self-consumption and
battery-backup function
Multicluster system with increased self-consumption and
battery-backup function
Multicluster system with stand-alone grid Off-grid system
Sunny Boy, Sunny Tripower PV inverter
SunnyIsland 6.0H / 8.0H Sunny Island, battery inverter
1.8 Additional Information
For more information, please go to www.SMA-Solar.com.
Title and information content Type of information
Mounting, installation, commissioning, operation, configuration, troubleshooting
and decommissioning of the inverter Operating manual
"Parameters and Measured Values"
Overview of all inverter operating parameters and their configuration options
Technical Information
MULTICLUSTER-BOX 12 Installation – circuitry overview
MULTICLUSTER-BOX 12 Operating manual
SUNNYISLAND 4.0M / 6.0H / 8.0H Operating manual
GRID-CONNECT-BOX 12 Operating manual

2 Safety
SMA Solar Technology AG
System Description 7SI44M-80H-13-MC-IA-en-10
2 Safety
2.1 Intended Use
The multicluster system forms an AC grid and is made up of several three-phase clusters. Three SunnyIsland are
connected in parallel on the DC side of each cluster. The multicluster system can be set up as an off-grid system or as a
system with increased self-consumption and battery-backup function.
The Multicluster-Box and Grid-Connect-Box do not replace the distribution board for the loads or the PV system. In
addition to the Multicluster-Box and Grid-Connect-Box, you must install the necessary protective devices for the loads
and the PV system.
Loads connected to the SunnyIsland must have an CE, RCM or UL identification label.
The product is not suitable for supplying life-sustaining medical devices. A power outage must not lead to personal
injury.
Only device types with the same output power may be installed in a cluster. This means that the device types, such as
SI6.0H-12 and SI6.0H-13, may be combined within a cluster. In contrast, device types with different outputs (e.g.
SI6.0H-13 and SI8.0H-13) may not be combined. The cluster master must always be an SI6.0H-13 / SI8.0H-13. It
must be equipped with the latest firmware version.
An utility grid connected to the multicluster system must be a TN or TT grid configuration. The technical connection
requirements of the grid operator and the local standards and directives must be fulfilled. When connecting the
multicluster system to the utility grid, all information in this quick reference guide and the instructions provided in the
enclosed documentation must be observed.
Generators must be suitable for TN systems and must always be connected to the Multicluster-Box.
The entire battery voltage range must be completely within the permissible DC input voltage range of the SunnyIsland.
The maximum permissible DC input voltage of the SunnyIsland must not be exceeded. A battery fuse must be installed
between the battery and the SunnyIsland.
With lead-acid batteries, the battery room must be ventilated in accordance with the requirements of the battery
manufacturer and with the locally applicable standards and directives (see documentation of the battery
manufacturer).
The following conditions must be satisfied for lithium-ion batteries:
• The lithium-ion battery must comply with the locally applicable standards and directives and must be intrinsically
safe.
• The battery management of the lithium-ion battery used must be compatible with the SunnyIsland (see the
technical information at “List of Approved Batteries”).
• The lithium-ion battery must be able to supply enough current at maximum output power of the SunnyIsland (for
technical data see the SunnyIsland operating manual).
An DC supply grid may not be established with the SunnyIsland.
The AC sources in the multicluster system must be suitable for stand-alone mode with SunnyIsland (for PV inverters see
planning guidelines "Design of Off-Grid Systems with SunnyIsland Devices" at www.SMA-Solar.com). The maximum
output power of the AC sources in a stand-alone grid must be observed (see the operating manual of the
SunnyIsland).
For a multicluster system with increased self-consumption and battery-backup function, the connected PV system must
be suitable for both stand-alone mode and utility grid operation (see the planning guidelines
"SMAFlexibleStorageSystem with Battery Backup Function" at www.SMA-Solar.com). The maximum output power of
the PV system depends on the installation site (see Section3.4.3, page20).
DC charge controllers may not be included in a multicluster system connected to the utility grid.
With the internal measuring device of the Multicluster-Box, the multicluster system detects the electricity fed into and
purchased from the grid at the grid connection point of the Grid-Connect-Box. The internal measuring device of the
Multicluster-Box does not replace the energy meter of the electric utility company.

2 Safety SMA Solar Technology AG
System DescriptionSI44M-80H-13-MC-IA-en-108
For PV system monitoring, only the SMAClusterController is used in multicluster systems.
Use SMA products only in accordance with the information provided in the enclosed documentation and with the
locally applicable laws, regulations, standards and directives. Any other application may cause personal injury or
property damage.
Alterations to the SMA products, e.g., changes or modifications, are only permitted with the express written permission
of SMA Solar Technology AG. Unauthorized alterations will void guarantee and warranty claims and in most cases
terminate the operating license. SMA Solar Technology AG shall not be held liable for any damage caused by such
changes.
Any use of the product other than that described in the Intended Use section does not qualify as the intended use.
The enclosed documentation is an integral part of this product. Keep the documentation in a convenient, dry place for
future reference and observe all instructions contained therein.
This document does not replace and is not intended to replace any local, state, provincial, federal or national laws,
regulations or codes applicable to the installation, electrical safety and use of the product. SMA Solar Technology AG
assumes no responsibility for the compliance or non-compliance with such laws or codes in connection with the
installation of the product.
2.2 IMPORTANT SAFETY INSTRUCTIONS
SAVE THESE INSTRUCTIONS
This section contains safety information that must be observed at all times when working.
The product has been designed and tested in accordance with international safety requirements. As with all electrical
or electronical devices, there are residual risks despite careful construction. To prevent personal injury and property
damage and to ensure long-term operation of the product, read this section carefully and observe all safety
information at all times.
DANGER
Danger to life due to electric shock when live components or cables are touched
High voltages are present in the conductive components or cables of the product. Touching live parts and cables
results in death or lethal injuries due to electric shock.
• Do not touch non-insulated parts or cables.
• Disconnect the system from voltage sources and make sure it cannot be reconnected before working on the
device.
• Observe all safety information on components associated with the product.
• Wear suitable personal protective equipment for all work on the product.
DANGER
Danger to life due to electric shock in case of overvoltages and if surge protection is missing
Overvoltages (e.g. in the event of a flash of lightning) can be further conducted into the building and to other
connected devices in the same network via the network cables or other data cables if there is no surge protection.
Touching live parts and cables results in death or lethal injuries due to electric shock.
• Ensure that all devices in the same network and the battery are integrated into the existing surge protection.
• When laying the network cables or other data cables outdoors, it must be ensured that a suitable surge
protection device is provided at the transition point of the cable from the product or the battery outdoors to the
inside of a building.

2 Safety
SMA Solar Technology AG
System Description 9SI44M-80H-13-MC-IA-en-10
DANGER
Danger to life due to electric shock in case of overvoltages and unsuitable loads
Overvoltages of up to 1500V can occur in the stand-alone grid and in the battery-backup grid. If the loads are not
suitable for these overvoltages or are not safe to operate, a voltage that poses a danger to life may be present on
accessible parts or cables. Touching live parts and cables results in death or lethal injuries due to electric shock.
• Only connect loads that have a CE, RCM or UL designation. These loads are suitable for overvoltages of up to
1500V.
• Operate the loads only when they are technically faultless and in an operationally safe state.
• Check the loads regularly for visible damage.
DANGER
Danger to life due to electric shock when operating a damaged product
Operating a damaged product can lead to hazardous situations since high voltages can be present on accessible
product parts. Touching live parts and cables results in death or lethal injuries due to electric shock.
• Only operate the system when it is in a flawless technical condition and safe to operate.
• Check the system regularly for visible damage.
• Make sure that all external safety equipment is freely accessible at all times.
• Make sure that all safety equipment is in good working order.
• Wear suitable personal protective equipment for all work on the product.
WARNING
Danger to life due to fire or explosion
In rare cases, an explosive gas mixture can be generated inside the inverter under fault conditions. In this state,
switching operations can cause a fire inside the inverter or explosion. Death or lethal injuries due to hot or flying
debris can result.
• In the event of a fault, do not perform any direct actions on the inverter.
• Ensure that unauthorized persons have no access to the inverter.
• Disconnect the battery from the product via an external disconnection device.
• Disconnect the AC circuit breaker, or keep it disconnected in case it has already tripped, and secure it against
reconnection.
• Only perform work on the inverter (e.g., troubleshooting, repair work) when wearing personal protective
equipment for handling of hazardous substances (e.g., safety gloves, eye and face protection, respiratory
protection).
WARNING
Risk of injury due to toxic substances, gases and dusts.
In rare cases, damages to electronic components can result in the formation of toxic substances, gases or dusts
inside the inverter. Touching toxic substances and inhaling toxic gases and dusts can cause skin irritation, burns or
poisoning, trouble breathing and nausea.
• Only perform work on the inverter (e.g., troubleshooting, repair work) when wearing personal protective
equipment for handling of hazardous substances (e.g., safety gloves, eye and face protection, respiratory
protection).
• Ensure that unauthorized persons have no access to the inverter.

2 Safety SMA Solar Technology AG
System DescriptionSI44M-80H-13-MC-IA-en-1010
WARNING
Danger to life from electric shock due to circuit breakers that cannot be tripped
In off-grid systems and battery-backup systems, the SunnyIsland can only trip circuit breakers up to a certain
tripping characteristic. Circuit breakers with a higher operating current cannot be tripped. Under fault conditions, a
voltage that poses a danger to life may be present on accessible parts for several seconds. Touching live
components can result in death or serious injury due to electric shock.
• SI6.0H-13 and SI8.0H-13: Check whether a circuit breaker has a higher trip characteristic than B16 (B16A) or
C6 (C6A).
• If a circuit breaker has a higher trip characteristic than the specified circuit breakers that can be tripped, you
should also install a residual-current device of type A.
WARNING
Risk of crushing injuries due to moving PV array parts
A generator can be started automatically by the SunnyIsland. Moving parts in the PV array can crush or sever
body parts.
• Operate the generator only with the specified safety equipment.
• Carry out all work on the generator in accordance with the manufacturer's specifications.
CAUTION
Risk of burns due to short-circuit currents on the disconnected inverter
The capacitors in the DC input area of the inverter store energy. After the battery is isolated from the inverter,
battery voltage is still temporarily present at the DC terminal. A short circuit at the DC terminal of the inverter can
lead to burns and may damage the inverter.
• Wait 15minutes before performing any work at the DC terminal or on the DC cables. This allows the
capacitors to discharge.
CAUTION
Risk of burns due to hot enclosure parts
Some parts of the enclosure can get hot during operation.
• Mount the inverter in such a way that it cannot be touched inadvertently during operation.
NOTICE
Damage to the system due to sand, dust and moisture ingress
Sand, dust and moisture penetration can damage the system and impair its functionality.
• Only open the product if the humidity is within the thresholds and the environment is free of sand and dust.
• Do not open the product during a dust storm or precipitation.
NOTICE
Damage to the inverter due to electrostatic discharge
Touching electronic components can cause damage to or destroy the inverter through electrostatic discharge.
• Ground yourself before touching any component.

2 Safety
SMA Solar Technology AG
System Description 11SI44M-80H-13-MC-IA-en-10
NOTICE
Damage to the enclosure seal in subfreezing conditions
If you open the product when temperatures are below freezing, the enclosure seals can be damaged. Moisture can
penetrate the product and damage it.
• Only open the product if the ambient temperature is not below -5°C.
• If a layer of ice has formed on the enclosure seal when temperatures are below freezing, remove it prior to
opening the product (e.g. by melting the ice with warm air).
NOTICE
High costs due to inappropriate Internet tariff
Depending on use, the data volume of the product transferred via the Internet may vary in size. The data volume
depends, for example, on the number of inverters in the system, the frequency of device updates, the frequency of
data transfer to SunnyPortal or the use of FTP push. High costs for the Internet connection can be the result.
• SMA Solar Technology AG recommends using an Internet flat rate.
The inverter supports different firmware versions that are suitable for different systems.
Inverters using firmware version ≤2.99.99.R are suitable for off-grid systems and systems that are not subject to
the European grid connection conditions in accordance with Regulation (EU) 2016/631 for establishing a
network code (also known as RfG). In addition, inverters with firmware version ≤2.99.99.R may be used in
systems that have been commissioned before April 27, 2019, and that are subject to the grid connection
conditions of VDE-AR-N 4105:2011-08.
Inverters using a firmware version ≥3.00.00.R are only suitable for systems that are operated in parallel with the
utility grid (e.g. SMAFlexibleStorageSystem). The firmware version ≥3.00.00.R complies with VDE-AR-N
4105-11:2018, EN50549-1:2018, C10/11:2018 and EREC G98:2018/G99:2018 of the European grid
connection conditions in accordance with Regulation (EU) 2016/631 for establishing a network code (also
known as RfG), valid from April 27, 2019 within the EU.
Inverters with a firmware version ≤2.99.99.R can be identified by the imprint 2:Off-Grid on the box label.
Invertes with a firmware version ≥3.00.00.R can be identified by the imprint 1:On-Grid on the box label.
• Ensure that the inverter is equipped with a firmware version that are suitable for the respective system.
Change to the names and units of grid parameters to comply with the grid-connection
requirements in accordance with Regulation (EU) 2016/631 (valid from April 27, 2019)
To comply with the EU grid-connection requirements (valid from April 27, 2019) the names and units of grid
parameters were changed. The change is valid from firmware version ≥3.00.00.R. Names and units of grid
parameters for inverters with firmware version ≤2.99.99.R are not affected by this change and remain valid.
2.3 Battery Safety Information
This section contains safety information that must be observed at all times when working on or with batteries.
To prevent personal injury or property damage and to ensure long-term operation of the batteries, read this section
carefully and observe all safety information at all times.

2 Safety SMA Solar Technology AG
System DescriptionSI44M-80H-13-MC-IA-en-1012
WARNING
Danger to life due to incompatible lithium-ion battery
An incompatible lithium-ion battery can lead to a fire or an explosion. With incompatible lithium-ion batteries, it is
not ensured that battery management is intrinsically safe and will protect the battery.
• Ensure that the lithium-ion batteries are approved for use with the SunnyIsland (see technical information “List
of Approved Batteries” at www.SMA-Solar.com).
• If no lithium-ion batteries approved for the inverter can be used, lead-acid batteries can be used.
• Verify that the battery complies with locally applicable standards and directives and is intrinsically safe.
WARNING
Danger to life due to explosive gases
Explosive gases may escape from the battery and cause an explosion.
• Protect the battery environment from open flames, embers and sparks.
• Install, operate and maintain the battery in accordance with the manufacturer’s specifications.
• Do not burn the battery and do not heat it beyond the permitted temperature.
• Additional measures for lead-acid batteries: Ensure that the battery room is sufficiently ventilated.
WARNING
Chemical burns due to battery electrolyte
If handled inappropriately, battery electrolyte can leak from the battery and cause irritation to the eyes, respiratory
system and skin.
• Install, operate, maintain and dispose of the battery according to the manufacturer’s specifications.
• Whenever working on the battery, wear suitable personal protective equipment such as rubber gloves, an
apron, rubber boots and goggles.
• Rinse acid splashes thoroughly for a long time with clear water, and consult a doctor immediately.
• If acid fumes have been inhaled, consult a doctor immediately.
WARNING
Danger to life due to burns caused by electric arcs through short-circuit currents
Short-circuit currents in the battery can cause heat build-up and electric arcs. Heat build-up and electric arcs may
result in lethal injuries due to burns.
• Remove watches, rings and other metal objects prior to carrying out any work on the battery.
• Use insulated tools for all work on the battery.
• Do not place tools or metal parts on the battery.
• Observe all safety information of the battery manufacturer.

2 Safety
SMA Solar Technology AG
System Description 13SI44M-80H-13-MC-IA-en-10
CAUTION
Risk of burns due to hot battery components
Improper battery connection may result in excessively high transition resistances. Excessive transition resistances
give rise to localized heat build-up.
• Ensure that all pole connectors are connected with the connecting torque specified by the battery
manufacturer.
• Ensure that all DC cables are connected with the connecting torque specified by the battery manufacturer.
NOTICE
Damage to the battery due to incorrect settings
The set battery parameters influence the charging behavior of the inverter. The battery can be damaged by
incorrect settings of the battery type, nominal voltage and capacity parameters.
• Set the correct battery type as well as the correct values for nominal voltage and battery capacity when
configuring.
• Ensure that the values recommended by the manufacturer are set for the battery (refer to the technical data of
the battery in the manufacturer documentation).

3 Functions and Design SMA Solar Technology AG
System DescriptionSI44M-80H-13-MC-IA-en-1014
3 Functions and Design
3.1 Design of a Multicluster-Box
5
3
MULTICLUSTER-BOX
GRID-CONNECT-
BOX
5
5
55
3 3
3
3 3
3
PV INVERTER
GENERATOR
LOADS
DC--
Communication
5-wire cable
DC+
3-wire cable
Extension Cluster
Main Cluster
UTILITY
GRID
optional
Figure 1: Principle of a multicluster system with Multicluster-Box and Grid-Connect-Box
The Multicluster-Box is the main AC distribution board in a multicluster system. The multicluster system forms an AC grid
and is made up of several three-phase clusters. Three Sunny Island inverters are connected in parallel on the DC side
of each cluster. The multicluster system can be set up as an off-grid system or as a system with increased self-
consumption and battery-backup function.
The maincluster is the leading cluster in the multicluster system. The extensionclusters are subordinate to the
maincluster.
PV arrays used as an external energy source must be connected only to the Multicluster-Box. To connect the utility grid
to the multicluster system, a Grid-Connect-Box must be installed.

3 Functions and Design
SMA Solar Technology AG
System Description 15SI44M-80H-13-MC-IA-en-10
3.2 Structures of a Multicluster System
3.2.1 Structures for Off-Grid Systems
Multicluster-Box only with Generator
MAIN
CLUSTER
EXTENSION
CLUSTER 1
EXTENSION
CLUSTER 3
MULTICLUSTER-BOX GENERATOR
LOAD
PV SYSTEM
Figure 2: Principle of a multicluster system with Multicluster-Box and generator
If only the generator as external energy source is connected to the Multicluster-Box, the multicluster system must be
configured via the installation assistant for Island mode.
Multicluster-Box with Grid-Connect-Box, Utility Grid and Generator
MAIN
CLUSTER EXTENSION CLUSTER 1 EXTENSION CLUSTER 3
GRID-CONNECT-
BOX
MULTICLUSTER-BOX
GENERATOR
LOAD
PV SYSTEM UTILITY GRID
Grid-connection point
with energy meter
of the
electric utility company
TN or TT system
Figure 3: Principle of a multicluster system with Multicluster-Box, GridConnect Box, utility grid, and generator

3 Functions and Design SMA Solar Technology AG
System DescriptionSI44M-80H-13-MC-IA-en-1016
The Grid-Connect-Box enables the connection of a multicluster system to utility grids and generators. Multicluster
systems with Grid-Connect-Box may not be connected to utility grids that require compliance with the European gird
connection conditions in accordance with Regulation (EU) 2016/631 establishing a network code (also known as
RfG).
If the utility grid only supports the generator function and no increased self-consumption is to be achieved, the
multicluster system with Grid-Connect-Box must be configured via the installation assistant for Island mode.
Multicluster-Box only with Utility Grid
MAIN
CLUSTER
EXTENSION
CLUSTER 1
EXTENSION
CLUSTER 3
MULTICLUSTER-BOX
LOAD
PV SYSTEM
UTILITY GRID
Figure 4: Principle of a multicluster system with Multicluster-Box and utility grid
If the utility grid is directly connected to the Multicluster-Box, no generator is to be installed in the multicluster system.
When connecting the utility grid to the Multicluster-Box, the Multicluster-Box terminal provided for the generator must
be used (see operating manual of the Multicluster-Box). The installer bears sole responsibility for the grounding
configuration and the grid disconnection required for instances of grid failure. Grounding and grid disconnection must
be carried out in accordance with local standards and directives and approved by the grid operator.
If the utility grid is used as the only external energy source and directly connected to the Multicluster-Box as well, the
multicluster system must be configured via the installation assistant for Island mode

3 Functions and Design
SMA Solar Technology AG
System Description 17SI44M-80H-13-MC-IA-en-10
3.2.2 Structure for Systems with Increased Self-Consumption and Battery-
Backup Function
MAIN
CLUSTER EXTENSION CLUSTER 1 EXTENSION CLUSTER 3
GRID-CONNECT-
BOX
MULTICLUSTER-BOX
GENERATOR
LOAD
PV SYSTEM UTILITY GRID
Grid-connection point
with energy meter
of the
electric utility company
TN or TT system
Figure 5: Principle of a multicluster system with Multicluster-Box, GridConnect Box, utility grid, and generator
The Grid-Connect-Box enables the connection of an utility grid and a generator to one multicluster system. In doing so,
the Grid-Connect-Box may only be used where the VDE-AR-N4105 application guide for utility grids is not required.
If increased self-consumption is required, the multicluster system with Grid-Connect-Box must be configured via the
installation assistant for Grid mode.
3.3 Off-Grid System
3.3.1 Off-Grid System Functions
Multicluster systems set up as off-grid systems can form self-sufficient utility grids fed with energy from multiple AC
sources in the stand-alone grid (e.g. PV inverter) and from grid-forming AC sources (e.g. a generator). The
SunnyIsland forms the stand-alone grid as a AC voltage source. The SunnyIsland regulates the balance between the
energy that is fed in and the energy that is used and features a battery, PV array and load management system.
Battery Management
Exact determination of the state of charge is a basic requirement for the correct operation of lead-acid batteries.
The SunnyIsland battery management system for lead-acid batteries is based on an exact determination of the state of
charge. By combining the three most common methods for recording the state of charge, the SunnyIsland reaches a
measuring accuracy of more than 95%. This way, battery overcharge and deep discharge are avoided.
Another advantage of the battery management system is the very gentle charging control. Depending on the battery
type and situation, it selects automatically the optimum charging strategy. This means that overcharging can be reliably
prevented and that the battery can be fully charged regularly. The available charge energy is used optimally at all
times (see technical information "Battery Management" at www.SMA-Solar.com).
Generator Management
The SunnyIsland can synchronize with a generator and connect directly, if necessary. When the stand-alone grid is
connected to the PV array, the voltage and frequency in the stand-alone grid are regulated by the PV array.

3 Functions and Design SMA Solar Technology AG
System DescriptionSI44M-80H-13-MC-IA-en-1018
The SunnyIsland generator management allows for uninterruptible connection of the stand-alone grid to the generator
and uninterruptible isolation from the generator. The generator management controls the generator via a start and stop
signal. A generator current control ensures that the generator always remains at the optimum operating point. The
generator management allows the use of generators that have a low output power in proportion to the nominal load
(see technical document "Sunny Island Generator - Whitepaper" at www.SMA-Solar.com)
Load Control
The load control enables control of the AC sources in stand-alone grids, control of a generator, and the specific
disconnection of loads.
The AC sources in the off-grid system are limited in their power output by the stand-alone grid frequency. In case of
excess energy, the load control system increases the power frequency of the stand-alone grid. This limits the output
power of the PV inverters, for example.
If there is not enough energy available for all loads or the battery is to be preserved, load control can request energy
from a generator by means of the generator management. The generator management starts the generator and the off-
grid system is supplied with sufficient energy.
If no generator is present in the off-grid system or the energy is not sufficient despite the generator being available,
load control turns the loads off using load shedding. All loads are shed simultaneously with one-stage load shedding.
A load shedding contactor sheds the noncritical loads during the first stage with two-stage load shedding. The
remaining loads are shed during the second stage only when the state of charge declines further. This can further
increase the availability of the stand-alone grid for critical loads.
3.3.2 Off-Grid System Requirements
Utility grid connection via Grid-Connect-Box
The utility grid can support or assume the function of a PV array in, for example, areas with a weak grid structure.
To connect the utility grid and generator in parallel to an off-grid system, a Grid-Connect-Box must be installed.
The Grid-Connect-Box may be used only in areas where VDE-AR-N4105 application guide does not apply.
The Grid-Connect-Box is always delivered with all-pole disconnection. If, during a grid failure, the technical
connection requirements of the grid operator or the locally applicable standards and directives prohibit
disconnection of the neutral conductor, you must deactivate the all-pole disconnection in the Grid-Connect-Box
(see operating manual of the Grid-Connect-Box).
Utility grid connection to the Multicluster-Box
If the utility grid is directly connected to the Multicluster-Box, no generator is to be installed in the multicluster
system. When connecting the utility grid to the Multicluster-Box, the Multicluster-Box terminal provided for the
generator must be used (see operating manual of the Multicluster-Box).
The installer bears sole responsibility for the grounding configuration and the grid disconnection required for
instances of grid failure. Grounding and grid disconnection must be carried out in accordance with local
standards and directives and approved by the grid operator.
3.3.3 Optional Devices and Functions
The following devices can be used optionally in an off-grid system:
Component Description
External load-shedding contactor Contactor controlled by the SunnyIsland for isolation of loads in the multicluster
system during two-level load shedding.
SMA Cluster Controller Remote monitoring and system configuration of the off-grid system

3 Functions and Design
SMA Solar Technology AG
System Description 19SI44M-80H-13-MC-IA-en-10
The SunnyIsland inverter offers the following functions for multicluster systems with stand-alone grid via two
multifunction relays (see installation manual of the SunnyIsland inverter):
Function Description
Controlling PV arrays A multifunction relay activates if a PV array request is received from the SunnyIs-
land inverter's generator management system. With the multifunction relay, you
can control PV arrays with an electrical remote-start function or connect a signal
generator for PV arrays with no autostart function.
Controlling load-shedding con-
tactors A multifunction relay is activated depending on the state of charge of the battery. Depending on the configuration, you can install a one-level load shedding with
one multifunction relay or a two-level load shedding with two multifunction relays.
You can also adjust the thresholds for the state of charge of the battery depend-
ing on the time of day.
Time control for external pro-
cesses External processes can be time-controlled with a multifunction relay.
Display of operating states and
warning messages You can connect message devices to the multifunction relays to allow operating states and warning messages from the SunnyIsland inverter to be output. One of
the following operating states and warning messages can be displayed for each
multifunction relay:
• The PV array is running and is connected.
• A SunnyIsland displays an error message of level 2 or higher. Only the
error messages within a cluster are evaluated here.
• A SunnyIsland displays a warning. Only the warnings within a cluster are
evaluated here.
Control of a battery-room fan The multifunction relay is activated when the charging current causes the battery
to emit gasses. A connected battery room fan is switched on for at least one
hour.
Control of an electrolyte pump Depending on the nominal energy throughput, the multifunction relay is activated
at least once a day.
Use of excess energy During the constant voltage phase, a multifunction relay is activated and thus
controls additional loads that can put any excess energy of AC sources in the
stand-alone grid (e.g., of a PV system) to good use.
3.4 Multicluster System with Increased Self-Consumption and Battery-
Backup Function
3.4.1 Principle of a System with Increased Self-Consumption and Battery-Backup
Function
Multicluster systems with increased self-consumption and battery-backup function (battery-backup systems) are
connected to the utility grid via a Grid-Connect-Box.
When the system with increased self-consumption and battery-backup function is connected to the utility grid,
SunnyIsland inverters can use the batteries for intermediate storage of PV energy. The stored PV energy can then be
used by your appliances during the evening and nighttime hours. With this, electricity purchased from the grid can be
reduced and self-consumption or internal power supply optimized.

3 Functions and Design SMA Solar Technology AG
System DescriptionSI44M-80H-13-MC-IA-en-1020
The GridConnectBox disconnects the system with increased self-consumption and battery-backup function from the
utility grid during grid failure. The loads are supplied with power via the battery-backup grid without interruption. The
PV system can synchronize with the system with increased self-consumption and battery-backup function and feed in.
When the utility grid is available again, the system with increased self-consumption and battery-backup function
synchronizes with the utility grid. Following successful synchronization, the GridConnectBox connects the system with
increased self-consumption and battery-backup function to the utility grid.
3.4.2 Requirements of VDE Application Guide 2510-2
The requirements below apply only for systems for which the following properties are all applicable:
• The system is a system with increased self-consumption (SMAFlexibleStorageSystem) or a system with increased
self-consumption and battery-backup function (battery-backup system).
• The grid operator or the locally applicable standards and guidelines require compliance with the above-
mentioned Application Guide.
Currently, only the grid operators in Germany require compliance with the above-mentioned Application Guide.
In accordance with the scope of VDE application guide 2510-2, a manufacturer's system is regarded as a complete
energy storage system only if products are used that have been approved by the manufacturer (see the technical
information “List of Approved Batteries” at www.SMA-Solar.com). If products are used that have not been approved
by SMASolarTechnologyAG, the installer is deemed to be the manufacturer of the system.
The requirements of VDE application guide 2510-2 are fulfilled if the installation is carried out in the accordance with
the technical documentation of the battery inverter.
3.4.3 Requirements for Systems with Increased Self-Consumption and Battery-
Backup Function
Utility grid connection via Grid-Connect-Box
The Grid-Connect-Box may be used only in areas where VDE-AR-N4105 application guide does not apply.
The Grid-Connect-Box is always delivered with all-pole disconnection. If, during a grid failure, the technical
connection requirements of the grid operator or the locally applicable standards and directives prohibit
disconnection of the neutral conductor, you must deactivate the all-pole disconnection in the Grid-Connect-Box
(see operating manual of the Grid-Connect-Box).
Electricity supply of communication devices
During a grid failure, only the devices in the battery-backup grid are supplied with current.
• Connect the electricity supply of communication devices to the battery-backup grid.