Fronius Fronius String Control 250/25 USA Operating Instruction [EN]

/ Battery Charging Systems / Welding Technology / Solar Electronics

Fronius String Control 250/25

Operating Instructions

Data Communication

EN-US

42,0426,0082,EA 005-12042012

Dear Fronius Customer,

Introduction

Thank you for choosing Fronius - and congratulations on your new, high-quality, high­tech Fronius product. This introduction should provide you with general information
about the equipment. Please read it carefully to learn about the many great features of
your new Fronius product. This is the best way to get the most out of all the advantages
that it has to offer.

Please also note the safety information and the safety precautions for the product
installation location. Following all product instructions will ensure long-lasting quality and
reliability. And these are the essential ingredients for outstanding results.

EN-US

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IMPORTANT SAFETY

INSTRUCTIONS

SAVE THESE INSTRUCTIONS

General This manual contains important instructions for the Fronius String Control

250/25, that must be followed during installation and maintenance.

The Fronius String Control 250/25 is designed and tested according to
international safety requirements, but as with all electrical and electronic
equipment, certain precautions must be observed when installing and/or
operating the Fronius String Control 250/25.
To reduce the risk of personal injury and to ensure the safe installation
and operation of the Fronius String Control 250/25, you must carefully
read and follow all instructions and safety instructions in this manual.

EN-US

Safety Instruc­tions

Electrical
installations

The following section “Safety Instructions“ contains different warnings. A
warning describes a hazard to equipment or personnel. It calls attention to
a procedure or practice, which, if not correctly performed or adhered to,
could result in damage to or destruction of part or all of the Fronius string
Control 250/25 and/or other equipment connected to the Fronius String
Control 250/25 or personal injury.

All electrical installations must be made in accordance with the National
Electrical Code, ANSI/NFPA 70, and any other codes and regulations
applicable to the installation site.

For installations in Canada the installations must be done in accordance
with applicable Canadian standards.

2

Safety Instructions

Explanation of
Safety Warnings!

General

„DANGER!“ Indicates an immediate danger. Death or serious injury may

result if appropriate precautions are not taken.

EN-US

„WARNING!“ indicates a potentially dangerous situation. Death or serious
injury may result if appropriate precautions are not taken.

„CAUTION!“ Indicates a situation where damage or injury could occur. Minor
injury or damage to property may result if appropriate precautions are not
taken.

NOTE! Indicates a situation which could adversely affect work results and may
cause damage to equipment.

„Important“ Highlights tips for correct operation and other particularly useful
information. It does not indicate a potentially damaging or dangerous situation.

If you see any of the symbols depicted in the „Safety Rules,“ special care is required.

This equipment has been manufactured using state-of-the-art technology
and in accordance with general safety regulations. However, incorrect
operation or misuse may endanger:

- the life and well-being of the operator or third parties

- the equipment and other property of the owner/operator

- the efficient operation of the equipment.

All persons involved with equipment startup, service and maintenance must:

- be suitably qualified

- be familiar with electrical installations

- have completely read and followed these operating instructions

The operating instructions must be available at the equipment location at all
times. In addition to the operating instructions, all applicable local rules and
regulations regarding accident prevention and environmental protection must
also be followed.

All safety instructions and warning signs on the equipment itself:

- must be maintained in legible condition

- must not be damaged

- must not be removed

- must not be covered or painted over

For information about where the safety instructions and warning signs are
located on the equipment, please refer to the “General“ section of your
equipment’s operating instructions.

Any equipment malfunctions which might impair safety must be remedied
immediately before the device is turned on.

Your safety is at stake.

I

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Intended Use

The equipment may only be operated in compliance with its intended use.

Any other purpose does not constitute intended use. The manufacturer is not
responsible for any damages resulting from unintended use.

Intended use also includes:

- reading and complying with all general information as well as safety
information and warnings from the operating instructions

- compliance with all inspection and maintenance requirements

- installation as per operating instructions

Where appropriate, the following guidelines should also be applied:

- Utility company regulations regarding grid feed-in

- Information from solar module manufacturer

Ambient Conditi­ons

Qualified Person­nel

Operation and/or storage of the device outside of the stipulated range does
not constitute intended use. The manufacturer is not responsible for any
damages resulting from unintended use.

Please refer to the technical data in your operating instructions for informati­on about permitted ambient conditions.

The servicing information contained in these operating instructions is intended
only for the use of qualified service engineers. An electric shock can be fatal.
Please do not perform any actions other than those described in the docu­mentation. This also applies to qualified personnel.

All cables and wires must be secured, undamaged, insulated and adequately
dimensioned. Loose connections, scorched, damaged or under-dimensioned
cables and wires must be repaired immediately by an authorized specialist.

Maintenance and repair may only be carried out by an authorized specialist.

The use of third-party parts does not guarantee that they were designed and
manufactured according to operational demands and safety requirements.
Use only original spare parts (also applies to standard parts).

Safety Precauti­ons at Equipment
Location

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Do not carry out any alterations, installations or modifications to the device
without first obtaining the manufacturer’s permission.

Immediately replace any components that are not in perfect condition.

When installing devices with air vents, make sure that cool air can flow freely through the
vents unobstructed. The device should only be operated in accordance with the protec­tion class listed on the rating plate.

II

Information on
Noise Emission
Values

The inverter generates a maximum sound power level of <80dB(A) (ref.
1pW) at full-load operation according to IEC 62109-1.

The cooling of the device takes place via an electronic temperature control
system at the lowest possible noise level and depends on the power used,
ambient temperature and the soiling level of the device, etc.

A workplace-related emissions value cannot be provided for this device
because the actual noise level that occurs depends strongly on the installati­on situation, the grid quality, the surrounding walls and the general properties
of the space.

EMC Device
Classifications

Devices in emission class A:

- Are only designed for use in industrial settings

- Can cause grid-bound and radiated interference in other areas

Devices in emission class B:

- Satisfy the emissions criteria for residential and industrial areas.
This is also true for residential areas in which the energy is
supplied from the public low-voltage grid.

EMC device classification as per the rating plate or technical data

EMC Precautions In special cases, there may still be interference for the specified application

area despite maintaining standardized emission limit values (e.g. when
sensitive equipment is located at the setup location or when the setup
location is near radio or television receivers).
In this case, the operator is obliged to take proper action to rectify the
situation.

EN-US

Grid connection

Devices with a high output (> 16 A) can influence the voltage quality of the
grid due to a high current input into the main supply.
This can affect several device types in the form of:

- Connection limitations

- Requirements regarding permitted mains impedance

- Requirements regarding minimum required short circuit power

*)

for each interface to the public grid

*)

*)

See technical data

In this case, the operator or the user of the device must make sure whether
or not the device may be connected, if necessary by contacting the power
supply company.

III

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Electrical Installa­tions

Electrical installations may only be carried out in accordance with relevant
national and local standards and regulations.

ESD Precautions

Safety Precauti­ons in Normal­Operation

Safety Markings

Danger of damage to electronic components due to electrostatic discharge.
Take appropriate ESD precautions when replacing and installing compon­ents.

The device should only be operated when all safety equipment is fully func­tional. If safety equipment is not fully functional, there is a danger to:

- the life and well-being of the operator or third parties

- the equipment and other property of the owner/operator

- the efficient operation of the equipment

Safety equipment that is not fully functional must be repaired by an authori­zed specialist before the device is turned on.

Never bypass or disable safety equipment.

Equipment with the CE marking fulfils the basic requirements of the Guideli­ne Governing Low-Voltage and Electromagnetic Compatibility. (For more
information, please see the attachment and/or the “Technical Data“ section in
your documentation).

Disposal

Data Security

Copyright

This device should not be disposed of in residential waste.
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 returned to an approved recycling facility. Any device that you no longer
require must be returned to your dealer or you must find an approved collec­tion and recycling facility in your area.
Ignoring this EU Directive may have adverse affects on the environment and
your health.

The user is responsible for backing up data relating to changes made to
factory settings. The manufacturer will not accept liability if personal settings
are deleted.

The manufacturer maintains the copyright to these operating instructions.

Text and illustrations are technically correct at the time of going to print. The
right to make modifications is reserved. The contents of the operating in­structions shall not provide the basis for any claims whatsoever on the part
of the purchaser. We would be grateful for any comments or suggestions
regarding improvements and/or error corrections for the operating instruc­tions.

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IV

Contents

General ............................................................................................................................... 3

Functional Principle ........................................................................................................ 3

Other System Requirements ........................................................................................... 3

Device Concept .............................................................................................................. 3

FCC Compliance ........................................................................................................... 4

Standards and Regulations ............................................................................................. 4

Intended Use .................................................................................................................. 4

Abbreviations and Descriptions Used ............................................................................. 4

Product listings and compliance ..................................................................................... 4

Components Supplied .................................................................................................... 4

Product Description ............................................................................................................ 5

Safety ............................................................................................................................. 5

Fronius String Control 250/25 - Housing.......................................................................... 5

Fronius String Control 250/25 - Connection Area ............................................................ 6

Selecting a Location ....................................................................................................... 8

Fronius String Control 250/25 Installation ............................................................................. 8

Wall anchors and Screws ................................................................................................ 8

Recommended Screws for Mounting .............................................................................. 8

Installation Position ......................................................................................................... 8

Safety ............................................................................................................................. 8

Drilling Pattern ................................................................................................................9

Attaching the Fronius String Control 250/25 to a Concrete or Brick Wall .......................... 9

Attaching the Fronius String Control 250/25 to a Wooden Wall ...................................... 10

Attaching the Fronius String Control 250/25 to a Metal Carrier ..................................... 10

Knocking out Cable Input Openings and Mounting Conduits on the Fronius String Control

250/25 ............................................................................................................................... 11

General ......................................................................................................................... 11

Cable Input Areas .......................................................................................................... 11

Maximum Conduit Size ................................................................................................. 12

Recommendation for Inserting Cables .......................................................................... 12

Preparation .................................................................................................................. 12

Knocking out Cabel Input Openings on the Fonius String Control 250/25 ....................... 13

Mounting Conduits on the Fronius String Control 250/25 .............................................. 13

Connecting Solar Module Strings to the Fronius String Control 250/25 .............................. 14

General Information About Solar Modules ..................................................................... 14

Safety ........................................................................................................................... 14

Necessary Inside Cable Length of the Fronius String Control 250/25............................. 15

Notes for Connecting Solar Module Strings to the Fronius String Control 250/25 ........... 16

Terminal Assignment with Grounded Solar Modules ...................................................... 16

Connecting Solar Module Strings to the Fronius String Control 250/25 .......................... 17

Connecting the Fronius String Control 250/25 to the Inverter .............................................. 18

Safety ........................................................................................................................... 18

Cable Lugs for DC Cable ‘OUT’ ................................................................................... 19

Preparation .................................................................................................................. 19

Connecting DC Cable ‘OUT’ to the Fronius String Control 250/25 ................................. 20

Connecting the Fronius String Control 250/25 to the Inverter.......................................... 20

EN-US

1

Criteria for the Proper Selection of String Fuses................................................................ 22

General ........................................................................................................................ 22

Criteria for the Proper Selection of String Fuses ........................................................... 22

Effects of Using Underrated Fuses ............................................................................... 22

Fuse Recommendations ............................................................................................... 22

Fuses ...........................................................................................................................23

Application Example ..................................................................................................... 23

Inserting String Fuses........................................................................................................ 24

Selecting String Fuses .................................................................................................. 24

Inserting String Fuses ................................................................................................... 24

Safety ........................................................................................................................... 24

Connecting Data Communication Cables to the Fronius String Control 250/25.................. 25

Connection Options ...................................................................................................... 25

Additional Insulation for Data Communication Cables ................................................... 25

Configuration example .................................................................................................. 26

Safety ........................................................................................................................... 26

Connecting RJ 45 Data Communication Cables to the Fronius String Control 250/25 ... 27

Connecting Unterminated Multi-core Data Communication Cables to the Fronius String

Control 250/25 .............................................................................................................. 27

Terminal assignments ................................................................................................... 28

Connecting an External Power Supply ............................................................................... 29

General ........................................................................................................................ 29

Safety ........................................................................................................................... 29

Connecting an External Power Supply........................................................................... 29

Setting the Address........................................................................................................... 30

Safety ........................................................................................................................... 30

General ........................................................................................................................ 30

Setting the Address - Examples .................................................................................... 30

Installing the Protection Against Contact and Closing the Fronius String Control 250/25 .... 31

Safety ........................................................................................................................... 31

Installing Protection Against Contact ............................................................................. 31

Closing the Fronius String Control 250/25 ..................................................................... 31

Settings ............................................................................................................................ 32

General ........................................................................................................................ 32

Initial Steps ...................................................................................................................32

Possible Settings for the Fronius String Control 250/25................................................. 32

Strings per Measuring Channel ..................................................................................... 33

Max. Energy Deviation .................................................................................................. 33

Threshold...................................................................................................................... 33

Display of Data and Status Messages ............................................................................... 34

Data Display................................................................................................................. 34

Status Messages .......................................................................................................... 34

Replacing String Fuses ..................................................................................................... 35

Safety ........................................................................................................................... 35

Preparation .................................................................................................................. 35

Replacing String Fuses................................................................................................. 35

Finally... ........................................................................................................................ 36

Technical Data ..................................................................................................................37

Input data ...................................................................................................................... 37

Output data (to the inverter) ........................................................................................... 37

General Data ................................................................................................................ 38

2

General

Device Con­cept

The Fronius String Control 250/25
is designed for use in grid-con­nected photovoltaic systems with
several solar module strings.

Up to 25 solar module strings can
be integrated at the input of the
Fronius String Control 250/25 to
reduce these at the output to one
DC+ and DC- main line.
The Fronius String Control 250/25
monitors the incoming solar module
strings to detect errors in the solar

Fronius String Control 250/25 (open)

Status messages can be sent via e-mail or SMS when using the “Fronius
Solar.access“ software together with the “Fronius Datalogger.“
This allows a defective solar module to be detected quickly.

module field.

EN-US

Functional
Principle

Other System
Requirements

- Each set of 5 incoming solar module strings is grouped into one
measuring channel.

- 5 measuring channels record the total current of the respective con­nected solar module strings over the entire charging day.

- In the evening, the Fronius String Control 250/25 calculates an ave­rage value for all measuring channels.

- The Fronius String Control 250/25 compares the current of each
measuring channel with the average value of all measuring channels.

- If the Fronius String Control 250/25 detects that one of the measuring
channels deviates too much from the average, a status message is
sent to the Fronius Datalogger.

- The permitted deviation from the average is freely definable.

- Fronius Datalogger

- PC with Fronius Solar.access software installed

3

Intended Use

The device is intended solely for use as a collector and measuring device
for the solar module DC strings.
The device may be operated only with the following inverters:

- Fronius CL 33.3 DELTA / 44.4 DELTA / 55.5 DELTA

- Fronius CL 36.0 WYE 277 / 48.0 WYE 277 / 60.0 WYE 277

Any other purpose does not constitute intended use.
The manufacturer shall not be liable for any damage resulting from such
improper use.

Intended use also includes following all information from the operating
instructions.

Components
Supplied

FCC Compli­ance

Standards and
Regulations

- 1 Fronius String Control 250/25

- 1 silicone tube

This device complies with Part 15 of the FCC Rules. Operation
is subject to the following conditions:
(1) This device may not cause harmful interference, and
(2) this device must accept any interference received, including
interference that may cause undesired operation.

Your Fronius String Control 250/25 complies with the requirements for the
following standards "Inverters, converters and controllers for use in inde­pendent power systems":

- UL1741-2005

- ANSI / IEEE C62.41

- C22.2 No. 107.1-01 (Sep. 2001)

Product lis­tings and
compliance

Abbreviations
and Descripti­ons Used

The respective conformity declarations can be found in the appendix to
these operating instructions.

DC cable ‘OUT’ DC output cable from Fronius String Control 250/25

to inverter.
The polarity of the DC cable ‘OUT’ depends on how
the solar module strings are connected to the Fronius
String Control 250/25.

DC cable ‘IN’ Solar module strings from the solar modules to the

Fronius String Control 250/25.
Each solar module string has one DC+ cable and one
DC- cable.

4

WARNING! Operating the device incorrectly can cause serious
injury and damage. The following documentation should be
read and understood in its entirety before the described func­tions are carried out:

- These operating instructions

- All system component operating instructions including
safety instructions

Product Description

Safety

EN-US

Fronius String
Control 250/25

- Housing

(1)

(2)

(3)

Item Description

(1) Cover screws (4 x)

(2) Cover

(3) Membrane

(4) Lower mounting clip

(6)
(5)

(4)

(5) Housing ground (inside the housing)

(6) Upper mounting clip

Sides for possible cable input openings

5

Fronius String
Control 250/25

- Connection

Area

(1)

(15)

(14)

(2)

(3)

(4)

(5)

(6)

(7)

(13)

(12)

(11)

(10)

(8)

(9)

Item Description

(1) Address switches

(2) Measuring channel 5

(3) Measuring channel 4

(4) Measuring channel 3

(5) 25 Terminals with fuse holders for DC cable ‘IN’

cable cross section AWG 14 - AWG 8

(6) Measuring channel 2

(7) Measuring channel 1

(8) Connection 2 x M12 for DC cables ‘OUT’

(9) Connection 2 x M12 for DC cables ‘OUT’

(10) Connection 2 x M12 for grounding

(11) 2 x 8 Pressure type terminals for data communication cable

cable cross section max. AWG 14

(12) 25 Terminals for DC cable ‘IN’

cable cross section AWG 14 - AWG 8

(13) 13 Grounding terminals (e.g. for grounding of max. 25 solar

module frames)
cable cross section max. AWG 6

6

Fronius String
Control 250/25

- Connection

Area

(continued)

Item Description

(14) 2 RJ 45 connections for data communication cable

(15) Connection for external 12 V DC power supply

EN-US

7

Fronius String Control 250/25 Installation

CAUTION! Danger of injury by falling objects.

When working on elevated workplaces make sure that no
objects like housing cover, tools or other components of the
system can fall down. If necessary, install a wire mesh, a safe­ty net or suitable protection devices.

Wall anchors
and Screws

Recommen­ded Screws
for Mounting

Installation
Position

Selecting a
Location

Depending on the surface, different wall anchors and screws may be
required for installing the Fronius String Control 250/25. Therefore, these
wall anchors and screws are not included with the Fronius String Control
250/25. The installer is responsible for selecting the proper wall anchors
and screws.

In most cases, you should use 1/4 in. or 5/16 in. stainless steel or alumini­um screws capable of supporting 46.26 lbs.

The Fronius String Control 250/25 can be installed in any position from
horizontal to vertical. However, the cable inputs and outputs should point
downwards as much as possible.

When selecting the location, please observe the following criteria:

- Install on a solid and planar surface; the housing must not be distorted
when screwing it down.

- The ambient temperature may not fall below -13 °F (-25 °C) nor exceed
+ 140 °F (+60 °C).

- NEMA 3R protection means that the Fronius String Control 250/25 is
not susceptible to water spray from any direction. However, the ma­nufacturer recommends, if possible, that the String Control 250/25 not
be exposed to direct moisture or to a direct water jet (e.g., from sprink­lers).

- Protect from direct sunlight and direct exposure to the elements.

- Install under the solar modules where possible.

Safety

8

Drilling Pat­tern

(a)

(a)

(a) = 8.86 in (225 mm)

(b) = 28.86 in. (733 mm)

(c) = 29.4 in. (746 mm)

Attaching the
Fronius String
Control 250/25
to a Concrete
or Brick Wall

(b)

(c)

(d) = 9.84 in. (250 mm)

EN-US

(d)

1

2

1

1

3

4

2

2

3

4

5

5

3

1

4 x

3

2

4

5

9

Attaching the
Fronius String
Control 250/25
to a Wooden
Wall

1

1

1

2

2

1

Attaching the
Fronius String
Control 250/25
to a Metal
Carrier

3

2

1

1

4 x

2

3

4

10

Knocking out Cable Input Openings and Moun­ting Conduits on the Fronius String Control
250/25

EN-US

General

Cable Input
Areas

Required cable input openings have to be knocked out of the Fronius
String Control 250/25 housing with a proper knock out tool.
Take care that safety notes and rating plates located on the housing are
not damaged when knocking out cable input openings.

Generally cables can be lead into the Fronius String Control 250/25 from
below or sidwise.
The following figure shows all possible cable input areas and the approp­riate measurements. On grey marked areas cable input openings can be
knocked out on the Fronius String Control 250/25.

DC OUT

GROUNDING OUT

= Cable input areas

DC OUT

GROUNDING OUT

11

DC OUT

GROUNDING OUT

Maximum
Conduit Size

The Fronius String Control 250/25 is designed for a maximum conduit
size of 4 in.

Recommenda­tion for Inser­ting Cables

Preparation

Fronius recommends inserting all cables from below into the Fronius
String Control 250/25.
The following working steps refer to inserting cables from below. Connec­ting sidewise inserted cables is similar and will not be described in these
operating instructions.

1

4x

1

2

1

3

2

3

1

1

1

2

2

2

12

Knocking out
Cabel Input
Openings on
the Fonius
String Control
250/25

CAUTION! Danger of short circuit by loose metal parts from

knockouts. Loose metal parts in the Fronius String Control 250/
25 may cause short circuits when the Fronius String Control
250/25 is powered up. When removing knockouts, make sure
that:

- no loose metal parts fall into the fronius string Control 250/
25

- any metal pieces that do fall into the Fronius String Control
250/25 are removed immediately

3/4 in.

EN-US

Mounting
Conduits on
the Fronius
String Control
250/25

DATCOM

Example of possible cable input openings

1. Knock out the required cable input openings using a proper knock out

1

DC INDC IN

3 in.

4 in.3 in.

DC OUT

tool

Consider safety notes of the knock out tool manufacturer

NOTE! Only use water tight conduit fittings and conduits for
outdoor installations.
Conduit fittings and conduits are not included with the Fronius
String Control 250/25.

1

1. Mount conduits and conduit fittings according to the cable input ope­nings

13

Connecting Solar Module Strings to the Fronius
String Control 250/25

General Infor­mation About
Solar Modules

Safety

In order to select suitable solar modules and get the most efficient use out
of the inverter, please note the following points:

- The open circuit voltage of the solar modules increases at constant
irradiance and when temperature decreases. The open circuit voltage
should never rise above the admissible inverter voltage, assuming an
irradiance of 1000 W/m² and a temperature of 14 °F (-10 °C).
Whenever the open circuit voltage of the solar modules exceeds the
admissible inverter voltage, the inverter may be damaged, and all
warranty rights will become null and void.

- More exact data for sizing the solar array for the particular location
can be obtained using calculation tools such as the Fronius Configura­tion Tool (available on http://www.fronius-usa.com).

- See NEC table 690.7 for the appropriate code-related voltage adjust­ment factor for crystalline silicon modules, or use the manufacturer’s
specified voltage coefficient.

WARNING! An electrical shock can be fatal. Danger from DC
voltage from solar modules.

- Make sure that the input and output sides in front of the
device are not charged before connecting anything.

- Any and all connections should only be carried out by quali­fied electricians.

- Follow the safety rules in these operating instructions.

WARNING! An electric shock can be fatal. Inadequately sized
electrical components can cause serious injuries to persons
and damage to (or loss of) property.

- All electrical installations must be in accordance with the

National Electrical Code, ANSI/NFPA 70, and any other
codes and regulations applicable to the installation site.

- For installations in Canada the installations must be done in

accordance with applicable Canadian standards.

- Use minimum AWG 12, min. 194 °F (90 °C), copper wire for

all grounding wires .

- For appropriate grounding see NEC table 250.122.

- Use minimum AWG 12 to maximum AWG 8, min. 194 °F

(90 °C), copper or aluminium wire for all DC wiring connec­tions to the Fronius String Control 250/25. Voltage drop and
other considerations may dictate larger size wires be used.

- Use only solid or stranded wire. Do not use fine stranded

wire.

14

Safety

(continued)

CAUTION! Danger of damaging the Fronius String Control 250/
25 from improperly connected terminals. Improperly connected
terminals can cause thermal damage to the Fronius String
Control 250/25 and may cause a fire. When connecting all DC
‘IN’ and DC ‘OUT’ cables, make sure that all terminals are
tightened securely using the proper torque.

EN-US

Necessary
Inside Cable
Length of the
Fronius String
Control 250/25

To ensure problem-free DC cable connections to the terminals, all DC
cables inside the Fronius String Control 250/25 must have a certain mini­mum length.
Depending on which side the DC cables are inserted from into the Fronius
String Control 250/25, different minimum lengths of the DC cables are
needed.

For the minimum inside cable length of the Fronius String Control 250/25:

- consider the guidelines in the following figure

- consider the mandatory forming of a min. 4 in. wire loop

25.16 in.

639 mm

7.83 in.

199 mm

3.98 in. 3.90 in.

101 mm

15

99 mm

20.08 in.

25.47 in.

647 mm

12.05 in.

306 mm

306 mm

Notes for
Connecting
Solar Module
Strings to the
Fronius String
Control 250/25

NOTE! Connecting the DC wiring with the

wrong polarity may cause damage to the
Fronius String Control 250/25.
Check both the polarity and the open
circuit voltage.

The DC Voltage must not exceed 600 V, regard­less of temperature.

NOTE! When connecting fewer than 25 solar module strings, we
recommend assigning an equal number of DC cables to the
measuring channels as much as possible.
For example: When connecting 15 solar module strings, connect
3 DC cables per measuring channel. If possible, leave individual
terminals free between the DC cables.

NOTE! When connecting Aluminium cables:

- consider national and international rules for connecting Alumi­nium cables

- consider technical information of the cable manufacturer

Terminal Assi­gnment with
Grounded
Solar Modules

With grounded solar modules, the ungrounded poles of the solar module
strings must be connected to the fused terminals (A).

Negative Grounding

Positive Grounding

DC- DC+

B (in) B‘ (out) A‘ (out) A (in)

DC+ DC-

B (in) B‘ (out) A‘ (out) A (in)

16

Connecting
Solar Module
Strings to the
Fronius String
Control 250/25

CAUTION! Danger of damaging the Fronius String Control 250/

25 by overload. Connect a maximum of 20 A to any DC input
terminal, maximum 50 A per measuring channel.

1 2

Tightening torque

1.48 ft lb.

10mm

*)

1

4

3

2

4

Tightening torque

0.39 in.
10 mm

1.48 ft lb.

5

1

2

3

*) Connect grounding cables (e.g. from solar module frame) if available.

The third grounding terminal from top can only be connected from the
side near the housing.

3

EN-US

Tightening torque

1.48 ft lb.

2

NOTE!

Form a min. 4 in. wire loop using all wires.

3

0.39 in.
10 mm

4

1

17

Connecting the Fronius String Control 250/25 to
the Inverter

Safety

WARNING! An electrical shock can be fatal. Danger from DC

voltage from solar modules.

- Make sure that the input and output sides in front of the
device are not charged before connecting anything.

- Any and all connections should only be carried out by quali­fied electricians.

- Follow the safety rules in these operating instructions.

WARNING! An electric shock can be fatal. Inadequately sized
electrical components can cause serious injuries to persons
and damage to (or loss of) property.

- All electrical installations must be in accordance with the
National Electrical Code, ANSI/NFPA 70, and any other
codes and regulations applicable to the installation site.

- For installations in Canada the installations must be done in
accordance with applicable Canadian standards.

- Use minimum AWG 12, min. 194 °F (90 °C), copper wire for
all grounding wires .

- For appropriate grounding see NEC table 250.122.

- Use maximum 250 MCM for cable input from below and
350 MCM for sidewise cable input, min. 194 °F (90 °C),
copper wire for all DC wiring connections to the inverter.
Voltage drop and other considerations may dictate larger
size wires be used.

- Use only solid or stranded wire. Do not use fine stranded
wire.

WARNING! An electric shock can be fatal. Normally grounded
conductors may be ungrounded and energized when a ground
fault is indicated. The ground fault has to be repaired before
operation is resumed.

NOTE! Do not connect the ground to the negative DC line at any
point! This is already done within the inverter. If negative DC lines
are connected to the DC terminals or prior to this to the ground,
this will circumvent the GFDI protection system, preventing your
inverter from properly detecting a fault current. Additionally, tur­ning the DC disconnect to the off/open-circuit condition will not
disconnect the array from ground, as it only disconnects the DC
positive.

18

Safety

(continued)

Consider the maximum inverter current, when sizing the DC cables ‘OUT’.

For the required cable cross section you can also use 2 cables. In this
case the cable cross section of both cables should be approximately of
the same size.

Cable Lugs for
DC Cable
‘OUT’

CAUTION! Danger of damaging the Fronius String Control 250/

25 from improperly connected terminals. Improperly connected
terminals can cause thermal damage to the Fronius String
Control 250/25 and may cause a fire. When connecting all DC
‘IN’ and DC ‘OUT’ cables, make sure that all terminals are
tightened securely using the proper torque.

For DC cables ‘OUT’ single hole and 2-hole cable lugs according the
following specification can be used:

Dx

x

max

x

max

0.47 in. 1.14 in. 1.50 in.

max

(M12) (29 mm) (38.1 mm)

D

D

Cable lugs must comply with natio­nal regulations and guide lines.

h

EN-US

h

Preparation

D

1

2

1

DC cable ‘OUT’

4

3

2

1

2

2x

1

2

2x

19

Connecting
DC Cable
‘OUT’ to the
Fronius String
Control 250/25

1

3

2

1

2x

4

2

3

2

1

2x

4

Tightening torque 20.65 ft lb. Tightening torque 20.65 ft lb.

NOTE! Label the DC cables ‘OUT’ according to their designated
polarity.

3

3

2

1

2x

5

Tightening torque 20.65 ft lb.

1

2

1

2

*

1
2

Connection of 1 or 2 cables per DC output

* Important! When connecting 2 cables with a 2-hole cable lug consi-

der, that both cable lugs may only be put together on their flat side.

1

2

NOTE!

Form a min. 4 in. wire loop using all wires.

20

Connecting
the Fronius
String Control
250/25 to the
Inverter

1. Connect the DC cable ‘OUT’ to the inverter as per the inverter opera-

1

ting instructions.

NOTE! Note the following points when connecting:

- String fuses must always be in the ungrounded conductor

- Connect the DC cable ‘OUT’ to the inverter with the correct
polarity.

NOTE! Connecting the DC wiring with the
wrong polarity may cause damage to the
inverter.
Check both the polarity and the open
circuit voltage.

The DC Voltage must not exceed 600 V, regard­less of temperature.

EN-US

21

Criteria for the Proper Selection of String Fuses

General The use of string fuses in the Fronius String Control 250/25 US also adds

fuse protection to the solar modules.
A crucial factor for the fuse protection of solar modules is the maximum
short circuit current ISC of the respective solar module.

Criteria for the
Proper Selec­tion of String
Fuses

Effects of
Using Under­rated Fuses

The following criteria must be fulfilled for each solar module string when
using fuse protection:

-IN > 1.8 x I

-IN < 2.4 x I

SC

SC

-VN ≥ max. input voltage of inverter being used:

FRONIUS CL....................................... 600 V DC

IN....... Nominal current rating of fuse

ISC..... short circuit current for standard test conditions (STC) according to

solar module data sheet

VN..... Nominal voltage rating of fuse

NOTE! The string fuse size must not be greater than the maxi­mum fuse current rating of the PV module as provided on the PV
module manufacturers data sheet. If no maximum fuse size is
indicated, please contact the PV module manufacturer.

If the fuses are underrated, the nominal current rating of the fuse can be
lower than the short circuit current of the solar module.
Negative effect:
The fuse may open under high irradiance conditions.

Fuse Recom­mendations

NOTE Only select fuses whose nominal voltage is higher or

equal to the max. input voltage of the inverter being used.

You should only use the following fuses, which have been tested by Froni­us, to ensure problem-free fuse protection:

- Littelfuse KLKD fuses

Fronius shall not be liable for any damage or other incidents resulting
from the use of other fuses. In addition, all warranty claims are forfeited.

22

Application
Example

Example: Maximum short circuit current (ISC) of the solar module = 5.75 A

According to the criteria for selecting the correct fuse, the fuse must have
a nominal current greater than 1.8 times and less than 2.4 times the short
circuit current:

- 5.75 A x 1.8 = 10.35 A

- 5.75 A x 2.4 = 13.8 A

The fuse that should be selected according to the „Fuses“ table: KLK D12
with 12.0 A nominal current and nominal voltage 600 V AC / DC.

EN-US

Fuses

Nominal Fuse
current value

4.0 A KLK D 4

5.0 A KLK D 5

6.0 A KLK D 6

7.0 A KLK D 7

8.0 A KLK D 8

‘Fuses’ table: Excerpt of suitable fuses, e.g. Littelfuse fuses

Nominal Fuse
current value

9.0 A KLK D 9

10.0 A KLK D 10

12.0 A KLK D 12

15.0 A KLK D 15

20.0 A KLK D 20

23

Inserting String Fuses

Safety

Selecting
String Fuses

WARNING! An electrical shock can be fatal. Danger from DC

voltage from solar modules.

- Make sure that the input and output sides in front of the
device are not charged before connecting anything.

- Any and all connections should only be carried out by quali­fied electricians.

- Follow the safety rules in these operating instructions.

Only use fuses for solar modules that meet the proper requirements for
string fuses from the solar module manufacturer or as per the „Criteria for
the Proper Selection of String Fuses“ section:

- max. 20 A per fuse holder

- max. 25 solar module strings

- max. 50 A per measuring channel

- max. 250 A of total input current

- Fuse dimensions: Diameter 0.41 x 1.38 - 1.50 in. (10.3 x 35 - 38 mm)

Important

- Please follow solar module safety instructions

- Follow all solar module manufacturer requirements

Inserting
String Fuses

NOTE Insert string fuses in the fuse holders corresponding to the

number of available solar modules.

1

1

2

2

3

24

Connecting Data Communication Cables to the
Fronius String Control 250/25

Connection
Options

There are two options for connecting the Fronius String Control 250/25 to
Solar Net:

- Via connection-ready data communication cables with RJ 45 plugs
Recommended cable size: CAT 5

- Via unterminated multi-core data communication cables
Max. cable cross section 2.5 mm²

(1) Terminals for unterminated

multi-core data communication
cables

(2) RJ 45 connections

(2)

(1)

EN-US

Additional
Insulation for
Data Commu­nication Ca­bles

Important! A silicone tube is included with the Fronius String Control 250/

25 for additional data communication cable insulation.
When laying the data communication cables on the inside of the Fronius
String Control 250/25, the data communication cables must be fed
through the silicone tube.

25

Configuration
example

Inverter
with Fronius Com Card

Fronius
String Control 250/25

IN

Fronius Datalogger Web

IN

OUT

IN 1 +12V

2 GND
3 Tx+
4 Rx+
5 Rx­6 Tx­7 GND
8 +12V

OUT 1 +12V

2 GND
3 Rx+
4 Tx+
5 Tx­6 Rx­7 GND
8 +12V

OUT

*)

Line/ISDN

OUTIN

*)

IN 1 +12V

2 GND
3 Tx+
4 Rx+
5 Rx­6 Tx­7 GND
8 +12V

OUT 1 +12V

2 GND
3 Rx+
4 Tx+
5 Tx­6 Rx­7 GND
8 +12V

IN 1 +12V

2 GND
3 Tx+
4 Rx+
5 Rx­6 Tx­7 GND
8 +12V

OUT 1 +12V

2 GND
3 Rx+
4 Tx+
5 Tx­6 Rx­7 GND
8 +12V

Safety

*) Termination plug

WARNING! An electrical shock can be fatal. Danger from DC
voltage from solar modules.

- Make sure that the input and output sides in front of the
device are not charged before connecting anything.

- Any and all connections should only be carried out by quali­fied electricians.

- Follow the safety rules in these operating instructions.

26

Connecting RJ

1

2

2

OUT

IN

IN

OUT

3

45 Data Com­munication
Cables to the
Fronius String
Control 250/25

1

*

*

2

EN-US

1

* Silicon tube

NOTE! Procedure when only 1 data communication cable is
being connected to the Fronius String Control 250/25 (e.g., when
the Fronius String Control 250/25 is the last component in a Solar
Net):

- Insert the termination plug in the free RJ 45 connection. The
termination plug is included with the Fronius Datalogger.

Connecting
Unterminated

1

Strip approx. 2 - 3 in. (50 - 70 mm) of insulation from the end of the
data communication cables

Multi-core
Data Commu-

2

nication Ca­bles to the
Fronius String
Control 250/25

*

3

2

0.39 in.

2

10 mm

1

IN

OUT

1

2

3

1

3

**

*

* Silicon tube
** Fixing lug

Important! You must know the assignment of each individual wire when
connecting the wires to the terminals.

Fix the data communicaton cables to the fixing lug using cable ties

27

Connecting
Unterminated
Multi-core
Data Commu­nication Ca­bles to the
Fronius String
Control 250/25

(continued)

NOTE! Procedure when only 1 unterminated multi-core data
communication cable is being connected to the Fronius String
Control 250/25 (e.g., when the Fronius String Control 250/25 is
the last component in a Solar Net):

- If the data communication cable is connected to the „IN“
terminals, connect the termination plug to the „OUT“ RJ 45
connection.

- If the data communication cable is connected to the „OUT“
terminals, connect the termination plug to the „IN“ RJ 45
connection.

The termination plug is supplied with the Fronius Datalogger.

Terminal
assignments

IN

OUT

+12 V
GND
TX­RX­RX+
TX+
GND
+12 V

+12 V
GND
RX­TX­TX+
RX+
GND
+12 V

28

Connecting an External Power Supply

2

1

General The Fronius String Control 250/25 is supplied power through Solar Net.

The power supply from Solar Net, however, may not be sufficient when
combined with additional DATCOM components or when data communi­cation cables exceed a length of 66 m.
In this case, an external power supply is available. (Fronius part number
43,0001,1211)

For reasons of access, Fronius recommends that the external power
supply be plugged into another DATCOM component rather than the
Fronius String Control 250/25 whenever possible.

If there is no other easier connection option, the following describes the
work steps involved in connecting the external power supply to the Froni­us String Control 250/25.

EN-US

Safety

Connecting an
External Po­wer Supply

WARNING! An electrical shock can be fatal. Danger from DC

voltage from solar modules.

- Make sure that the input and output sides in front of the
device are not charged before connecting anything.

- Any and all connections should only be carried out by quali­fied electricians.

- Follow the safety rules in these operating instructions.

1

Feed the power supply cable into the Fronius String Control 250/25
(e.g. together with data communication cables within the silicon tube)

*

* Silicon tube

29

Setting the Address

Safety

General

WARNING! An electrical shock can be fatal. Danger from DC

voltage from solar modules.

- Make sure that the input and output sides in front of the

device are not charged before connecting anything.

- Any and all connections should only be carried out by quali-

fied electricians.

- Follow the safety rules in these operating instructions.

Solar Net allows up to 200 Fronius String Control 250/25’s to operate
simultaneously. The individual Fronius String Controls are assigned
addresses to distinguish them from one another.
The address switch is used to set the address (0 to 199):

Setting the
Address ­Examples

1XX

0XX

(1)

(2)

(3)

(1) Jumper for the hundreds’ place
(2) Setting dial for the tens’ place
(3) Setting dial for the ones’ place

Fronius String Control 250/25
No. 1

Fronius String Control 250/25
No. 37

Fronius String Control 250/25
No. 123

0XX

1XX

010

0XX

1XX

370

0XX

1XX

231

30

Installing the Protection Against Contact and
Closing the Fronius String Control 250/25

Safety

Installing
Protection
Against Con­tact

WARNING! An electrical shock can be fatal. Danger from DC

EN-US

voltage from solar modules.

- Make sure that the input and output sides in front of the

device are not charged before connecting anything.

- Any and all connections should only be carried out by quali-

fied electricians.

- Follow the safety rules in these operating instructions.

1

3

3

2

2

3

2

1

1

1

Closing the
Fronius String
Control 250/25

Tightening torque 1.11 ft lb.

1

4

1

2

4x

3

2

1

31

Settings

General

Initial Steps - Install Fronius Solar.access software on a PC

Settings for the Fronius String Control 250/25 are made in the “Fronius
Solar.access“ software.

- Administration / Create PV System

- PV Systems / [System Name] / Settings / String Control

(1)

(2)

Possible Set­tings for the
Fronius String
Control 250/25

(3)

(1) Select the number (address) of the Fronius String Control 250/25 to

be set
(2) Strings per Measuring Channel
(3) Limit Values:

- Max. Energy Deviation in %

- Threshold Value in Ah per String

32

Strings per
Measuring
Channel

Max. Energy
Deviation

Enter the number of solar module strings for each measuring channel.
This results in automatic compensation of measuring channel deviations,
which would only be required if there were a different number of strings
per channel.

EN-US

The 5 measuring channels record the total current of the respective con­nected solar module strings over the entire charging day. In the evening,
the Fronius String Control 250/25 averages all measuring channels and
compares the current of each measuring channel with the average value
of all channels.
If the Fronius String Control 250/25 detects that one of the measuring
channels deviates too much from the average, a status message is sent
to the Fronius Datalogger.

The percentage deviation above which a measuring channel is conside­red faulty is defined in the “Max. Energy Deviation“ input field.

Standard value for max. energy deviation: 5 - 10 %

Threshold

If applicable, observe information from the solar module manufacturer.

The average electric charge (Ah) of all strings at which evaluation of
“Max. Energy Deviation“ is to start. This prevents possible status mes­sages in bad weather.

33

Display of Data and Status Messages

Data Display

Current data from the Fronius String Control 250/25 are displayed in:
PV Systems / [System Name] / Real-time / String Control

Status Mes­sages

Status messages generated by the Fronius String Control 250/25 are sent
to the datalogger. The datalogger processes this as it would a status
message generated by the inverter. Status messages can be sent as an
SMS, fax or e-mail. For further details please refer to the DATCOM opera­ting instructions.

The Fronius String Control 250/25 service codes are states 901 to 905.
These service codes indicate an excessive deviation in measuring chan­nels 1 to 5.

We recommend that you activate the earnings comparison in the “Set­tings - General“ menu. This provides you with a list of service messages
each time data are downloaded from the datalogger to the PC. This list
provides a quick overview of all the messages from the inverter and the
Fronius String Control 250/25.

34

Replacing String Fuses

Safety

Preparation

WARNING! Operating the equipment incorrectly can cause

serious injury and damage. The following activities must only
be carried out by trained and qualified personnel. Follow the
safety rules in these operating instructions.

WARNING! An electrical shock can be fatal. Danger from DC
voltage from solar modules.

- Make sure that the input and output sides in front of the
device are not charged before conducting maintenance
work.

- Never remove a fuse while it is under load.

1

Disconnect AC power at the inverter

2

Attach a clearly legible and easy-to-understand warning sign to prevent
anyone from switching it back on or from reconnecting any open or
interrupted connections

EN-US

Replacing
String Fuses

3

Check to make sure that solar module strings are deenergized

Short circuit solar module strings

5

Remove the cover

Test the fuse holder at the terminals for continuity

6

NOTE! Only use fuses for solar modules that meet the proper
requirements for string fuses.
Fuse dimensions: Diameter 0.41 x 1.38 - 1.50 in. (10.3 x 35 - 38
mm)

35

Replacing
String Fuses

(continued)

1

1

2

2

1

3

3

Find out and correct the cause of the defective fuse

Reattach the coverFinally...

1

Remove the short circuit to the solar module strings

2

Reconnect solar module strings to the Fronius String Control 250/25

3

Reestablish the connection to the AC supply lines

36

Technical Data

Input data

DC input voltage range 0 - 600 V

Max. input voltage 600 V
(at 1000 W/m² / 14°F in open circuit operation)

Max. array short circuit current 12.5 A
per string (1.25 * Imax)

Max. number of strings (with solar module fuse) 25

Admissible cable cross section min. AWG 12 - max. AWG 8
(for DC cable ‘IN’) Copper

solid and stranded conductors

Number of measuring channels 5

Max. current per measuring channel 50 A

Max. input current per fuse holder 20 A

Max. fuse size (10 x 38 class CC fuse) 20 A, 600 V

Number of grounding terminals 25

Admissible cable cross section min. AWG 12 - max. AWG 6
for grounding cables Copper

solid and stranded conductors

EN-US

Output data
(to the inver­ter)

Max. continuous DC current 250 A

Admissible cable cross section for DC cables ‘OUT’

cable outlet from below 250 MCM
cable outlet from side 350 MCM

Copper

solid and stranded conductors

Number of DC+ output terminals 1

Number of DC- output terminals 1

Number of grounding terminals 1

Connection possibilities per output pole or 2 x M12 (0.47 in.)
grounding terminal

Max. number of cables per output pole or 2
grounding terminal

Cable lugs for output poles or single hole cable lug
grounding terminal or 2-hole cable lug

37

General Data

Protection type NEMA 3R

Protection class Type 1 (grounded)

Ambient conditions -13°F - +140°F

-25°C - +60°C

Dimensions w x h x d (without mounting clips) 27.56 x 19.53 x 5.00 in.

700 x 496 x 127 mm

Dimensions w x h x d (with mounting clips) 30.63 x 19.53 x 5.00 in.

778 x 496 x 127 mm

Weight 26.46 lbs.

12 kg

Relative humidity 0 - 95 %

(non condensing)

Housing material Aluminium

Power supply via Solar Net

optional UL listed Class 2 (12V DC)

communication protocol SolarNet, RS 485

Connectors for data communication 2 x RJ 45

or 2 x 8 pressure type terminals

38

EN-US

39

40

Fronius Worldwide - www.fronius.com/addresses

Fronius International GmbH

4600 Wels, Froniusplatz 1, Austria
E-Mail: [e-mail]
http://www.fronius.com

Under http://www.fronius.com/addresses you will find all addresses of our sales branches and partner firms!

Fronius USA LLC Solar Electronics Division

USAA

10421 Citation Drive, Suite 1100, Brighton, MI 48116
E-Mail: [e-mail]
http://www.fronius-usa.com

ud_fr_se_so_00913 012011