SIST-TS CLC/TS 51643-32:2020

Low-voltage surge protective devices - Part 32: Surge protective devices connected to the DC side of photovoltaic installations - Selection and application principles

This document describes the principles for selection, installation and coordination of SPDs intended for use in Photovoltaic (PV) systems up to 1500 V DC and for the AC side of the PV system rated up to 1000 V rms 50/60 Hz.
The photovoltaic installation extends from a PV array or a set of interconnected PV-modules to include the associated cabling and protective devices and the converter up to the connection point in the distribution board or the utility supply point.
This document considers SPDs used in different locations and in different kinds of PV systems:
-   PV systems located on the top of a building;
-   PV systems located on the ground like free field power plants characterized by multiple earthing and a meshed earthing system.
The term PV installation is used to refer to both kinds of PV systems. The term PV power plant is only used for extended free-field multi-earthed power systems located on the ground.
For PV installations including batteries additional requirements could be necessary.
NOTE 1   The HD 60364 series, EN 62305 series and CLC/TS 61643 12 also apply.
NOTE 2   This document deals only with SPDs and not with surge protective components integrated inside equipment (e.g. inverters, (PCE) power conversion equipment).

Überspannungsschutzgeräte für Niederspannung – Teil 32: Überspannungsschutzgeräte für den Einsatz auf der Gleichstromseite von Photovoltaik-Installationen – Auswahl und Anwendungsgrundsätze

Parafoudres basse tension - Partie 32 : Parafoudres connectés au côté courant continu des installations photovoltaïques - Principes de choix et d’application

Nizkonapetostne naprave za zaščito pred prenapetostnimi udari - 32. del: Naprave za zaščito pred prenapetostnimi udari, priključene na enosmerno stran fotonapetostnih inštalacij - Izbira in načini uporabe

General Information

• Status: Published
• Publication Date: 19-Aug-2020
• ICS: 27.160 - Solar energy engineering
• ICS: 29.120.50 - Fuses and other overcurrent protection devices
• Technical Committee: POD - Surge aresters
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 31-Jul-2020
• Due Date: 05-Oct-2020
• Completion Date: 20-Aug-2020
• Ref Project: CLC/TS 51643-32:2020 - Low-voltage surge protective devices - Part 32: Surge protective devices connected to the DC side of photovoltaic installations - Selection and application principles

Relations

• Replaces: SIST-TS CLC/TS 50539-12:2014 - Low-voltage surge protective devices - Surge protective devices for specific application including d.c. -- Part 12: Selection and application principles - SPDs connected to photovoltaic installations
• Effective Date: 01-Sep-2020

Overview

CLC/TS 51643-32:2020 provides selection and application principles for surge protective devices (SPDs) used with photovoltaic (PV) installations. It covers SPDs on the DC side of PV arrays (systems up to 1500 V DC) and on the AC side of the PV system rated up to 1000 V rms (50/60 Hz). The Technical Specification addresses rooftop PV and ground-mounted free‑field PV power plants (including multi‑earthed, meshed earthing systems) and gives guidance for installation, coordination and maintenance of SPDs used to protect PV equipment from induced and direct lightning effects.

Key topics and requirements

• Scope & system boundaries: Applies from the PV array and associated cabling to the converter and point of connection in the distribution board or utility supply.
• SPD selection principles: Guidance on choosing SPD type and ratings based on PV source characteristics and system topology.
• Electrical parameters: Consideration of nominal discharge current (In), impulse current (Iimp), voltage protection level (Up), leakage current and rated impulse voltages for PV equipment.
• Installation & coordination: Recommended locations for SPDs on DC and AC sides, connection schemes (Y, D, U, L, I), and conductor cross‑sections for bonding conductors.
• Earthing arrangements: Requirements for equipotential bonding, multi‑earthed PV power plants and cases where separation distance to external LPS cannot be maintained.
• Special cases: Advice for installations that include communication/signalling circuits and PV systems with batteries (noting additional requirements may apply).
• Annexes & examples: Simplified methods to determine impulse discharge currents, PV source characteristics, and practical wiring/earthing diagrams.

Practical applications

This specification is practical for:

• PV system designers and electrical engineers selecting overvoltage protection for inverters, PV strings and combiners.
• Installers and EPC contractors implementing coordinated SPDs and earthing/bonding on rooftops and utility‑scale plants.
• Asset owners, O&M teams and safety assessors specifying maintenance, inspection and replacement criteria for SPDs.
• SPD manufacturers and component suppliers aligning product data (In, Iimp, Up, leakage) with PV‑specific requirements.

Related standards

• HD 60364 series (earthing/equipotential bonding)
• EN 62305 series (lightning protection)
• CLC/TS 61643‑12 (SPD selection principles for LV distribution)
• EN 61643‑31 (requirements/tests for SPDs for PV installations)

CLC/TS 51643‑32:2020 is a practical, system‑focused resource for ensuring reliable surge protection and coordinated installation of SPDs in modern PV installations.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2020
Nadomešča:
SIST-TS CLC/TS 50539-12:2014
Nizkonapetostne naprave za zaščito pred prenapetostnimi udari - 32. del: Naprave
za zaščito pred prenapetostnimi udari, priključene na enosmerno stran
fotonapetostnih inštalacij - Izbira in načini uporabe
Low-voltage surge protective devices - Part 32: Surge protective devices connected to
the DC side of photovoltaic installations - Selection and application principles
Ta slovenski standard je istoveten z: CLC/TS 51643-32:2020
ICS:
27.160 Sončna energija Solar energy engineering
29.120.50 Varovalke in druga Fuses and other overcurrent
nadtokovna zaščita protection devices
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

TECHNICAL SPECIFICATION CLC/TS 51643-32

SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
July 2020
ICS 27.160; 29.120.50 Supersedes CLC/TS 50539-12:2013
English Version
Low-voltage surge protective devices - Part 32: Surge protective
devices connected to the DC side of photovoltaic installations -
Selection and application principles
Parafoudres basse tension - Partie 32 : Parafoudres Überspannungsschutzgeräte für Niederspannung - Teil 32:
connectés au côté courant continu des installations Überspannungsschutzgeräte für den Einsatz auf der
photovoltaïques - Principes de choix et d’application Gleichstromseite von Photovoltaik-Installationen - Auswahl
und Anwendungsgrundsätze
This Technical Specification was approved by CENELEC on 2020-05-25.

CENELEC members are required to announce the existence of this TS in the same way as for an EN and to make the TS available promptly
at national level in an appropriate form. It is permissible to keep conflicting national standards in force.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.

European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2020 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. CLC/TS 51643-32:2020 E

Contents Page
European foreword . 5
Introduction . 6
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 8
4 Systems and equipment to be protected . 11
5 Overvoltages in a PV installation . 12
6 Selection and erection of SPDs. 12
6.1 General . 12
Table 1 — Selection of SPD type and cross section of bonding conductor . 13
6.2 Requirements for different PV installations . 13
6.2.1 General . 13
6.2.2 PV installation without an external LPS . 14
Figure 1 — Installation of SPDs in the case of a building without an external LPS . 14
6.2.3 PV installation with an external LPS when the separation distance (s) is
maintained (excluding multi-earthed solar systems, such as PV power plants) . 14
Figure 2 — Installation of SPDs in the case of a PV installation with an external LPS where the
separation distance (s) is maintained . 15
6.2.4 PV installation with an external LPS where the separation distance (s) cannot
be maintained (including multi-earthed systems, such as PV power plants) . 16
Figure 3 — Installation of SPDs in the case of a PV-installation with an external LPS where the
separation distance (s) cannot be maintained . 16
6.2.5 PV installation including communication and signalling circuits . 16
6.3 Selection and erection of SPDs installed on the AC side . 17
6.3.1 General . 17
6.3.2 Selection of SPDs with regard to nominal discharge current I and impulse
n
current I . 17
imp
6.3.3 Selection of SPDs with regard to voltage protection level U . 17
p
6.3.4 Installation of SPDs on the AC side . 17
Figure 4 — Installation of SPDs on the AC side with a short distance between the origin of the
installation and the PV inverter (E < 10 m) . 18
Figure 5 — Installation of SPDs on the AC side with a long distance between the origin of the
installation and the PV inverter (E ≥ 10 m) . 18
6.4 Selection and erection of SPDs installed on the DC side . 19
6.4.1 General . 19
6.4.2 Selection of SPDs with regard to nominal discharge current I and impulse
n
current I . 19
imp
6.4.3 Selection of U of SPDs on the DC side . 19
CPV
6.4.4 Selection of SPDs with regard to its leakage current I . 19
PE
6.4.5 Selection of SPDs with regard to voltage protection level U . 19
p
Table 2 — Rated impulse voltage U for equipment between PV array and inverter (where no
W
other information is available) . 20
6.4.6 Installation of SPDs on the DC side . 20
Figure 6 — Example of overvoltage protection on the DC side of a PV installation . 21
6.4.7 Cross-sections of connecting conductors for SPDs on the DC side . 21
6.4.8 Connection schemes of assemblies of SPDs on the DC side. . 22
Figure 7 — Example of connections (Y, D and U) on the DC side of a PV source. . 23
Figure 8 — Example of connections (L and I) on the DC side of a reliable earthed PV source
when distance between SPDs and the reliable earthing is less than 1 m. . 23
6.4.9 Selection of I of SPDs on the DC side . 23
SCPV
6.5 Coordination of SPDs . 24
7 Earthing Arrangement . 24
8 Requirements for the installation of surge protective devices (SPDs) in a PV system . 25
9 Maintenance . 25
Annex A (normative) Determination of the value of I or I for SPDs according to the
imp n
simplified approach for different structures protected by an LPS . 26
A.1 Introduction . 26
A.2 Building with a PV installation on the roof according to 6.2.4 . 27
Figure A.1 — Example of a structure with two external down conductors to determine the value
of the discharge current for the selection of SPDs . 29
Table A.1 — Values of I (I ) and I (I ) for voltage limiting SPDs on the DC side of
imp 10/350 n 8/20
a PV installation mounted on the roof of a building with an external LPS if the separation
distance is not maintained. . 29
Table A.2 — Values of I (I ) for voltage switching SPDs on the DC side of a PV
imp 10/350
installation mounted on the roof of a building with an external LPS, if the separation
distance is not maintained. . 30
A.3 Free- field PV power plant . 30
Figure A.2 — Example of the structure of an extended PV installation — A PV power plant with
multiple earthing and a meshed earthing system. 32
Table A.3 — Values of I (I and I (I ) for SPDs used on the DC side in PV
imp 10/350) n 8/20
power plants with a central inverter, multiple earthing and a meshed earthing system. 33
A.4 Selection of Type 1 SPDs impulse current I when A.2 or A.3 cannot be applied. . 34
imp
Annex B (informative) Characteristics of a PV source . 35
B.1 PV source characteristics . 35
Figure B.1 — Equivalent circuit diagram of a PV current source . 35
Figure B.2 — I/U characteristics of a PV source at different conditions . 36
Figure B.3 — Comparison of I/U characteristics of a PV source at different radiation conditions
and linear DC sources for SPD testing. . 37
B.2 Calculation of U . 38
OC MAX
B.3 Calculation of I . 38
SC MAX
Annex C (informative) Additional information to Clause 6: Selection and erection of SPDs and
to Clause 7: Earthing Arrangement . 39
C.1 PV installation including communication and signalling circuits . 39
Figure C.1 — Example of SPDs installed on a PV system protected by an external LPS where
the separation distance (s) is maintained – Installation includes data acquisition and
control system . 40
C.2 PV installation and dimensions of equipotential bonding conductors . 41
Figure C.2 — Example of a building with an external LPS – Dimensions of equipotential
bonding conductors when the separation distance (s) is maintained, or an isolated LPS is
used . 41
Figure C.3 — Example of a building with an external LPS – Dimensions of equipotential
bonding conductors when the separation distance (s) is not maintained. . 42
Bibliography . 43

European foreword
This document (CLC/TS 51643-32:2020) has been prepared by CLC/TC 37A ”Low-voltage surge
protective devices".
This document supersedes CLC/TS 50539-12:2013 and all of its amendments and corrigenda (if any).
CLC/TS 50539-12:2013:
 slight restructuring without impact on the content (such as changing the title of a clause by changing
the text of one clause to another),
 deletion of the current branch concept of an SPD,
 referring to EN 61634-11:2019 instead of EN 50539-11:2013,
 referring to OCFM, SCFM instead of acronyms and concepts SCM and OCM,
 deletion of Annex C relating to the simplified risk assessment A,
 addition of a new annex dealing with telecommunication circuits.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Introduction
This document provides useful information for the selection of SPDs connected to photovoltaic
installations.
This document does not address the fundamentals of SPDs that are addressed in CLC/TS 61643-12
which are necessary for its correct understanding and application.
This document provides information to evaluate, with reference to the documents listed in Clause 2, the
additional needs for surge protective devices (SPDs) to be installed on the DC side and on the AC side
of a photovoltaic (PV) system, to protect against induced and direct lightning effects. It gives guidance
for selection, operation and installation of SPDs, including the selection of SPD type, surge current
values and cross sections of bonding conductors.
The specific electrical parameters of a PV array or a PV source require specific SPDs on the DC side.
This document considers SPDs used in different locations and in different kinds of PV systems. It gives
examples and provides a simplified and common approach to determine impulse discharge current
values for the DC side of different PV installations.
1 Scope
This document describes the principles for selection, installation and coordination of SPDs intended for
use in Photovoltaic (PV) systems up to 1500 V DC and for the AC side of the PV system rated up to
1000 V RMS 50/60 Hz.
The photovoltaic installation extends from a PV array or a set of interconnected PV-modules to include
the associated cabling and protective devices and the converter up to the connection point in the
distribution board or the utility supply point.
This document considers SPDs used in different locations and in different kinds of PV systems:
— PV systems located on the top of a building;
— PV systems located on the ground like free field power plants characterized by multiple earthing
and a meshed earthing system.
The term PV installation is used to refer to both kinds of PV systems. The term PV power plant is only
used for extended free-field multi-earthed power systems located on the ground.
For PV installations including batteries additional requirements could be necessary.
NOTE 1 The HD 60364 series, EN 62305 series and CLC/TS 61643-12 also apply.
NOTE 2 This document deals only with SPDs and not with surge protective components integrated inside
equipment (e.g. inverters, (PCE) power conversion equipment).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
HD 60364-5-534:2016, Low-voltage electrical installations - Part 5-53: Selection and erection of
electrical equipment - Isolation, switching and control - Clause 534: Devices for protection against
transient overvoltages (IEC 60364-5-53:2001/A2:2015, modified)
EN 60664-1:2007, Insulation coordination for equipment within low-voltage systems - Part 1: Principles,
requirements and tests (IEC 60664-1:2007)
EN 61000-4-5, Electromagnetic compatibility (EMC) - Part 4-5: Testing and measurement techniques -
Surge immunity test (IEC 61000-4-5)
CLC/TS 61643-12, Low-voltage surge protective devices - Part 12: Surge protective devices connected
to low-voltage power distribution systems - Selection and application principles (IEC 61643-12)
EN 61643-31:2019, Low-voltage surge protective devices - Part 31: Requirements and test methods for
SPDs for photovoltaic installations (IEC 61643-31:2018)
ITU-T K.20, Resistibility of telecommunication equipment installed in a telecommunications centre to
overvoltages and overcurrents
ITU-T K.21, Resistibility of telecommunication equipment installed in customer premises to overvoltages
and overcurrents
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
PV array
assembly of electrically interconnected PV modules, PV strings or PV sub-arrays
Note 1 to entry: For the purposes of this document, a PV array is all components up to the DC input terminals
of the PCE or other power conversion equipment or DC loads. A PV array does not include its foundation, tracking
apparatus, thermal control and other such components.
Note 2 to entry: A PV array may consist of a single PV module, a single PV string, or several parallel-
connected strings, or several parallel-connected PV sub-arrays and their associated electrical components. For the
purposes of this standard, the boundary of a PV array is the output side of the PV array disconnecting device.
[SOURCE: HD 60364-7-712:2016, 712.3.3]
3.2
PV module
smallest complete environmentally protected assembly of interconnected cells
[SOURCE: HD 60364-7-712:2016, 712.3.1]
3.3
PV string
circuit of one or more series-connected modules
[SOURCE: HD 60364-7-712:2016, 712.3.2]
3.4
PV installation
erected equipment of a PV power supply installation
[SOURCE: HD 60364-7-712:2016, 712.3.14]
3.5
origin of the installation
point at which the electric energy is delivered to the electrical installation
[SOURCE: IEC 60050-826:2004, 826-10-02]
3.6
lightning protection system
LPS
complete system used to reduce physical damage due to lightning flashes to a structure
Note 1 to entry: It consists of both external and internal lightning protection systems.
[SOURCE: EN 62305-1:2011, 3.42]
3.7
external LPS isolated from the structure to be protected
LPS with an air-termination system and down conductor system installed in such a way that the path of
the lightning current has no contact with the structure to be protected
Note 1 to entry: In an isolated LPS, dangerous sparks between the LPS and the structure are avoided
[SOURCE: EN 62305-3:2011, 3.3]
3.8
surge protective device
SPD
device that contains at least one nonlinear component that is intended to limit surge voltages and divert
surge currents
Note 1 to entry: An SPD is a complete assembly, having appropriate connecting means.
[SOURCE: EN 61643-11:2012, 3.1.1]
3.9
separation distance
s
distance between two conductive parts at which no dangerous sparking can occur
[SOURCE: EN 62305-3:2011, 3.28]
3.10
bonding bar
metal bar on which metal installations, external conductive parts, electric power and telecommunication
lines, and other cables can be bonded to an LPS
[SOURCE: EN 62305-3:2011, 3.24]
3.11
bonding conductor
conductor connecting separated conductive parts to LPS
[SOURCE: EN 62305-3:2011, 3.25]
3.12
standard test conditions
STC
standard set of reference conditions used for the testing and rating of photovoltaic cells and modules
Note 1 to entry: See product standards (e.g. EN 61215).
Note 2 to entry: The standard test conditions given in EN 61215 for PV modules are:
a) PV cell temperature of 25 °C
b) Irradiance in plane of the PV cell or module of 1000 W/m2
c) Light spectrum corresponding to an atmospheric air mass of 1,5
[SOURCE: HD 60364-7-712:2016, 712.3.13]
3.13
open-circuit voltage under standard test conditions
U
OC STC
voltage under standard test conditions across an unloaded (open) PV module, PV string or PV array, or
on the DC side of the PV-inverter or power conversion equipment
[SOURCE: HD 60364-7-712:2016, 712.3.14, modified (addition of “-inverter or power conversion
equipment”)]
3.14
open-circuit maximum voltage
U
OC MAX
maximum voltage across an unloaded (open) PV module, PV string or PV array, or on the DC side of
the PV-inverter or power conversion equipment
Note 1 to entry: Calculation of U is performed in Annex B.
OC MAX
[SOURCE HD 60364-7-712:2016, 712.3.15 MOD]
3.15
short-circuit current under standard test conditions
I
SC STC
short-circuit current of a PV module, PV string or PV array under standard test conditions
[SOURCE: HD 60364-7-712:2016, 712.3.16]
3.16
short-circuit maximum current
I
SC MAX
maximum short-circuit current of a PV module, PV string or PV array
Note 1 to entry: Calculation of I is performed in Annex B.
SC MAX
[SOURCE: HD 60364-7-712:2016, 712.3.17]
3.17
maximum continuous operating voltage for PV application
U
CPV
maximum DC voltage which may be continuously applied to the SPD´s mode of protection
Note 1 to entry: The U values covered by this standard may exceed 1 500 V.
CPV
[SOURCE: EN 61643-31:2019, 3.1.10 modified (Notes to entry)]
3.18
short-circuit current rating of the SPD
I
SCPV
maximum prospective short-circuit current from the power system for which the SPD, in conjunction with
the disconnector specified, is rated
Note 1 to entry: This value is equal to or greater than I
SC MAX.
[SOURCE: EN 61643-31:2019, 3.1.25]
3.19
open-circuit failure mode
OCFM
failure behaviour whereby an SPD changes to a permanent high impedance or open circuit state under
certain conditions
Note 1 to entry: A low impedance intermediate state is possible for a limited time until the final failure mode is
reached.
[SOURCE: EN 61643-31:2019, 3.1.40]
3.20
short-circuit failure mode
SCFM
failure behaviour whereby an SPD changes to a permanent low impedance or short circuit state under
certain conditions
[SOURCE: EN 61643-31:2019, 3.1.41]
3.21
rated impulse voltage
U
w
impulse withstand voltage value assigned by the manufacturer to the equipment or to a part of it,
characterizing the specified withstand capability of its insulation against transient overvoltages
Note 1 to entry: For the purpose of this standard only withstand voltages between live conductors and earth
is considered.
Note 2 to entry: U is measured with a 1,2/50 µs voltage impulse wave shape.
W
Note 3 to entry: In some other standards also called U
imp.
[SOURCE: EN 60664-1:2007, 3.9.2, modified (addition of Notes to entry)]
3.22
total discharge current
I
Total
current which flows through the earth conductor of a multipole SPD during the total discharge current
test
Note 1 to entry: The aim is to take into account cumulative effects that occur when multiple modes of protection
of a multipole SPD conduct at the same time.
Note 2 to entry: I is particularly relevant for SPDs tested according to the Type 1 SPD test, and is used
Total
for the purpose of lightning protection equipotential bonding according to EN 62305 series.
[SOURCE: EN 61643-11:2012, 3.1.44, modified (“PE or PEN conductor” replaced by “earth conductor”)]
4 Systems and equipment to be protected
Equipment within a PV installation that may require protection includes:
— The inverter, i.e. both the AC interface with the AC LV power system and the DC interface;
— The PV array;
— The wiring (installation itself);
— Components installed between the inverter and the PV array;
— Equipment for controlling and monitoring the PV installation.
Overvoltages can destroy or degrade a PV installation or can cause malfunction, therefore PV
installations should be protected.
The evaluation of the need for protection and the proper selection of protective measures requires
information from the manufacturer concerning the withstand voltage of the equipment. If such
information is not readily available, the rated impulse voltage U for the equipment provided in 6.4.5
w
and in Table 2 can be used as a guide. Partial lightning currents can cause uncontrolled flashovers and
trigger fires. Surge protection measures may help to reduce the risk of fire (see the EN 62305 series).
5 Overvoltages in a PV installation
Several conditions may cause overvoltages in a PV installation. These include:
— direct strikes to the external lightning protection system (LPS) of the building or lightning flashes
near to the buildings and/or PV installation,
— direct strikes and lightning induced currents distributed into the electrical network,
— overvoltages created by the distribution network, e.g. those due to switching operations
Repetitive switching overvoltages (spikes) on the AC voltage created by electronic inverter / converter
technology may require special consideration for the selection of SPDs. For more information see
IEC/TR 62066.
The protection requirements in this document are based on the assumption that the cables
interconnecting the DC components of the PV installation are sufficiently protected from direct lightning
flashes, either by appropriate routing or by shielding (e.g. the use of an appropriate cable management
system).
6 Selection and erection of SPDs
6.1 General
According to CLC/TS 61643-12 and the EN 62305 series, selection and installation of SPDs for
protection of PV systems depend on many factors, but primarily:
— the lightning ground flash density N (flashes / km / year) or ground strike-point density N (strike-
g sg
point / km / year) of the location,
— the characteristics of the low-voltage power system (e.g. overhead lines or underground cables)
and of the equipment to be protected,
— whether the PV installation needs to be protected against direct lightning with an external LPS.
When installations are protected by an external LPS, the requirements for SPDs depend on:
— the selected class of the LPS (see simplified method in Annex A),
— whether the separation distance (s) is maintained between the LPS and the PV installation (isolated
LPS) or not maintained (non-isolated LPS).
For optimum inverter overvoltage protection, a direct earthing connection between the SPD and the
inverter is recommended.
The selection of SPD type and minimum cross section of bonding conductors should be done according
to Table 1.
Table 1 — Selection of SPD type and cross section of bonding conductor
Type of SPD and corresponding bonding cross sectional
areas
Situation SPD at Location SPD at Location SPD at Location
and
Type 1 SPD Type 2 SPD Type 2 SPD
according to
according to according to
a a a
EN 61643-11 EN 61643-11 EN 61643-31
2 2 2
16 mm 6 mm 6 mm
Installation of SPDs in case of
or
PV installation without external
LPS (see 6.2.2)
Type 2 SPD
according to
a
EN 61643-11
6 mm
Installation of SPDs in case of a Type 2 SPD Type 2 SPD
Type 1 SPD
building with external LPS when according to according to according to
separation distance s is kept EN 61643-11 EN 61643-11 EN 61643-31
2 2 2
16 mm 6 mm 6 mm
(see 6.2.3)
Installation of SPDs in case of a Type 1 SPD Type 1 SPD Type 1 SPD
building with external LPS when according to according to according to
separation distance s is not kept EN 61643-11 a EN 61643-31
EN 61643-11
2 2
16 mm 2 16 mm
(see 6.2.4 and Annex A) 16 mm
a
if necessary
NOTE The minimum cross sectional requirements of conductors differ in some countries. The European
foreword in EN 62305-3 explains these differences.
SPDs according to EN 61643-31 are marked with a PV sign.
6.2 Requirements for different PV installations
6.2.1 General
The general arrangements are shown in 6.2.2 to 6.2.5,
6.2.2 PV installation without an external LPS

Key
A Type 1 or Type 2 SPD according to EN 61643-11
B Type 2 SPD according to EN 61643-11
C Type 2 SPD according to EN 61643-31
D Type 2 SPD according to EN 61643-31
MDB Main Distribution Board
MEB Main Earthing Bar
ETSB Earth Termination System of Building
Grid Grid
Figure 1 — Installation of SPDs in the case of a building without an external LPS
In general, two SPDs on the DC side (location C and D) and two SPDs on the AC side of the inverter
(location A and B) should be installed as shown in Figure 1.
NOTE When a shielded DC power cable is used, the equipment interfaces with the cable are inherently
protected from induced overvoltages.
The SPD in location B is not required (see 6.3.2) if the distance between the SPD in the main distribution
board and the inverter is less than 10 m, and the PE conductor is routed with the AC power conductors.
In this case a single SPD should be installed in the main distribution board at location A.
The SPD in location B is also not required when the inverter and the main distribution board are
connected to the same earthing bar with a cable length each less than or equal to 0,5 m (e.g. the inverter
is located inside the main distribution board).
The SPD in location D is not required if:
— The distance between the inverter and the PV array is less than 10 m and the protection level (U )
p
of the SPD installed in location C is less than or equal to 0,8 U of the PV array’s withstand voltage
w
(see 6.4.5),
or
— The protection level (U ) of the SPD installed in location C is less than or equal to 0,5 U of the PV
p w
array’s withstand voltage and the PE conductor is routed close to the DC conductors.
6.2.3 PV installation with an external LPS when the separation distance (s) is maintained
(excluding multi-earthed solar systems, such as PV power plants)
This is a preferable solution compared to the case where the separation distance s is not maintained.
Measures to reduce the separation distance (s) (e.g. multiple or meshed down conductors) or use of an
external LPS isolated from the structure (the PV system being part of that structure) to be protected, are
preferred in comparison to the measures required in 6.2.3.
An external LPS isolated from the structure to be protected may be used only in the vicinity of the PV-
system (partly isolated LPS).
Key
A Type 1 SPD according to EN 61643-11
B Type 2 SPD according to EN 61643-11
C Type 2 SPD according to EN 61643-31
D Type 2 SPD according to EN 61643-31
x LPS air termination system
y LPS down conductor
MDB Main Distribution Board
MEB Main Earthing Bar
ETSB Earth Termination System of Building
Grid Grid
Figure 2 — Installation of SPDs in the case of a PV installation with an external LPS where the
separation distance (s) is maintained
In general, two SPDs on the DC side (location C and D) and two SPDs on the AC side of the inverter
(location A and B) should be installed, as shown in Figure 2. The SPD in location B is not required if the
distance between the SPDs in the main distribution board and the inverter is less than 10 m and the
induced voltage due to lightning current flowing in the down conductor can be ignored (see EN 62305-4).
The SPD in location B is not required when the inverter and the main distribution board are connected
to the same earthing bar with a cable of length less than or equal to 0,5 m (e.g. the inverter is located
inside the main distribution board).
The SPD in location D is not required if:
— The distance between the inverter and the PV array is less than 10 m and the protection level (U )
p
of the SPD installed in location C is less than or equal to 0,8 U of the PV array’s withstand voltage
w
(see 6.4.5),
or
— The protection level (U ) of the SPD installed in location C is less than or equal to 0,5 U of the PV
p w
array’s withstand voltage and the PE conductor is routed close to the DC conductors.
6.2.4 PV installation with an external LPS where the separation distance (s)
cannot be maintained (including multi-earthed systems, such as PV power plants)

Key
A Type 1 SPD according to EN 61643-11
B Type 1 SPD according to EN 61643-11 (see exception below)
C Type 1 SPD according to EN 61643-31
D Type 1 SPD according to EN 61643-31
E Equipotential bonding (separation distance is not maintained = non-isolated LPS)
x LPS air termination system
y LPS down conductor system
MDB Main Distribution Board
MEB Main Earthing Bar
ETSB Earth Termination System of Building
Grid Grid
Figure 3 — Installation of SPDs in the case of a PV-installation with an external LPS where the
separation distance (s) cannot be maintained
When protected by SPDs, other parts of the installation connected to the same bars may require Type
1 SPDs.
In this configuration the AC and the DC conductors act as parallel conductors to the equipotential
bonding conductors. Figure A.1 and Tables A.1 and A.2 provide further information relating to the
selection of the SPDs.
Type 1 SPDs are required for locations A, B, C and D. SPDs for location B and C should be installed as
close as possible to the inverter, as shown in Figure 3. The SPD in location D should be installed as
close as possible to the PV array.
In general, SPDs in location B and A are required, except where the inverter and the main distribution
board are connected to the same earthing bar with a cable length less than or equal to 0,5 m (e.g. the
inverter is located inside the main distribution board). In such a case the SPD in location B is not
required.
6.2.5 PV installation including communication and signalling circuits
Where SPDs are required for the power circuits, SPDs should also be considered for the
telecommunication and signalling circuits. An example is shown in Figure C.1.
6.3 Selection and erection of SPDs installed on the AC side
6.3.1 General
The selection and installation of SPDs for the protection of the AC side of PV installations should follow
the rules of HD 60364-5-534:2016, Clause 534, CLC/TS 61643-12 and EN 62305-4. The present
document takes into account only some specific details for the protection of the equipment on the AC
side of the PV installation.
The voltages between the AC conductors and earth depend on the inverter technology and are not
always purely sinusoidal AC voltages. Selection of SPDs on the AC side should take into consideration
the voltage waveform distortion, e.g. if significant spikes are expected.
6.3.2 Selection of SPDs with regard to nominal discharge current I and impulse current I
n imp
The minimum nominal discharge current I for each mode of protection should be 5 kA 8/20 for Type 2
n
SPDs. A higher value may result in a longer lifetime.
If a Type 1 SPD is required at the connection point between the PV installation and the public network
(usually at the main distribution board), this SPD should have a minimum impulse current I as
imp
required by HD HD 60364-5-534:2016, Clause 534 and CLC/TS 61643-12.
Higher values of I as defined by the EN 62305 series may be required. A simplified approach to
imp,
define the value of I depending on the risk according to the Lightning Protection Level (LPL) is given
imp
in CLC/TS 61643-12.
6.3.3 Selection of SPDs with regard to voltage protection level U
p
In order to select an SPD with the appropriate voltage protection level, the rated impulse voltage U of
w
the equipment and its EMC immunity level as defined by EN 61000-4-5 should be determined:
— for power lines and corresponding equipment terminations as defined by EN 61000-4-5,
HD 60364-4-443:2016, Clause 443 and EN 60664-1;
— for signalling lines and corresponding equipment terminations as defined by EN 61000-4-5,
ITU-T K.20 and ITU-T K.21.
To ensure effective protection of the equipment, the voltage protection level U should be lower than
p
the rated impulse voltage U of the equipment to be protected. In general a safety margin of at least
W
20 % between the rated impulse voltage of the equipment and U ≤ 0,8 times U should be maintained
p W
(see CLC/TS 61643-12 and EN 62305-4). See HD HD 60364-5-534:2016, Clause 534 for possible
exceptions. If not otherwise specified, the acceptable overvoltage category is category II. The maximum
impulse voltage expected to reach the equipment is then 2,5 kV for 230/400 V AC systems. This
generally requires a protection scheme with a number of coordinated SPDs. The manufacturers of SPDs
may provide the necessary information for such coordination.
6.3.4 Installation of SPDs on the AC side
For the case described in Clause 6.2.2 and 6.2.3 an SPD should be installed as close as possible to the
origin of the installation, e.g. at the connection point of the PV installation in the main distribution board
(Figure 4). If the length of the wiring between this SPD and the inverter (distance E) is equal to or greater
than 10 m, it is recommended that the inverter be protected with an additional SPD adjacent to that
inverter (Figure 5). In addition, the PE conductor should be routed close to the AC conductors.
For the case described in 6.2.4, the second SPD at the inverter should be installed.
If the total wire length as defined in Figure 4 and Figure 5 exceeds 0,5 m the requirements given in
HD HD 60364-5-534:2016, Clause 534.4.8 may apply.
Key
E Distance between origin of installation and inverter
L1, L2 and L3 Length of connecting cable
D external SPD disconnector
Figure 4 — Installation of SPDs on the AC side with a short distance between the origin of the
installation and the PV inverter (E < 10 m)

Key
E Distance between origin of installation and inverter
L1, L2 and L3 Length of connecting cable
D external SPD disconnector
Figure 5 — Installation of SPDs on the AC side with a long distance between the origin of the
installation and the PV inverter (E ≥ 10 m)
6.4 Selection and erection of SPDs installed on the DC side
6.4.1 General
The selection and installation of SPDs for the protection of the DC side of PV installations should follow
the rules of HD 60364-7-712. The present document gives additional information.
For SPDs installed on the DC side of PV systems the specific I/U-characteristic is considered for testing.
6.4.2 Selection of SPDs with regard to nominal discharge current I and impulse current I
n imp
The minimum nominal discharge current I should be 5 kA 8/20 per mode of protection for the Type 2
n
SPDs. A higher value may result in a longer SPD lifetime.
The selection of impulse current I for Type 1 SPDs should be made according to Annex A.
imp
6.4.3 Selection of U of SPDs on the DC side
CPV
The maximum continuous operating voltage U for all SPD modes of protection (±, +/earth and -
CPV
/earth) should be higher than or equal to the maximum open circuit voltage U of the PV array
OC MAX
under all service conditions (further information is given in Annex B).
6.4.4 Selection of SPDs with regard to its leakage current I
PE
Leakage current can be a selection parameter of the SPD when the installation required several SPDs
in parallel on the DC side and the sum of the leakage currents can reach values able to interact with the
good function of the inverter.
The voltage wave shape between the DC conductors and earth depends on the inverter technology and
are not always smooth DC. Selection of SPDs on the DC side should consider of the leakage current
resulting of this wave shape.
6.4.5 Selection of SPDs with regard to voltage protection level U
p
In order to identify the required protection level, it is necessary to determine the rated impulse voltage
U of the equipment or the equipment level immunity (see EN 61000-4-5) at the:
W
— power terminals according to EN 60664-1 and EN 61000-4-5,
— signalling and telecommunication ports according to EN 61000-4-5, ITU-T K.20 and ITU-T K.21.
One way to ensure effective protection of the equipment is to use SPD with a voltage protection level
U lower than the rated impulse voltage U of the equipment to be protected. In general a safety margin
p W
of at least 20 % between the rated impulse voltage of the equipment and U ≤ 0,8 times U should be
p W
maintained (see EN 62305-4).In addition, the PE conductor should be routed close to the DC
conductors. If no further information is given, the rated impulse voltage U for the equipment can be
W
selected from Table 2.
For circuits with SPDs consisting of a combination of single protection mode SPDs (Y, D, U, L, and I as
shown in Figure 7 and Figure 8), or for multipole SPDs, where not all possible modes of protection are
declared by the manufacturer, the voltage protection level of the individual SPDs should be added to
get t
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