MALAYSIAN MS 1837:2018
STANDARD
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(PV) system
(Second revision)
ICS: 27.160
Descriptors: installation, grid-connected, photovoltaic, system
© Copyright 2018
DEPARTMENT OF STANDARDS MALAYSIA
DEVELOPMENT OF MALAYSIAN STANDARDS
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standards and accreditation body of Malaysia.
The main function of STANDARDS MALAYSIA is to foster and promote standards,
standardisation and accreditation as a means of advancing the national economy, promoting
industrial efficiency and development, benefiting the health and safety of the public,
protecting the consumers, facilitating domestic and international trade and furthering
international cooperation in relation to standards and standardisation.
Malaysian Standards (MS) are developed through consensus by committees which comprise
balanced representation of producers, users, consumers and others with relevant interests,
as may be appropriate to the subject at hand. To the greatest extent possible, Malaysian
Standards are aligned to or are adoption of international standards. Approval of a standard
as a Malaysian Standard is governed by the Standards of Malaysia Act 1996 [Act 549].
Malaysian Standards are reviewed periodically. The use of Malaysian Standards is voluntary
except in so far as they are made mandatory by regulatory authorities by means of
regulations, local by-laws or any other similar ways.
For the purposes of Malaysian Standards, the following definitions apply:
Revision: A process where existing Malaysian Standard is reviewed and updated which
resulted in the publication of a new edition of the Malaysian Standard.
Confirmed MS: A Malaysian Standard that has been reviewed by the responsible
committee and confirmed that its contents are current.
Amendment: A process where a provision(s) of existing Malaysian Standard is altered. The
changes are indicated in an amendment page which is incorporated into the existing
Malaysian Standard. Amendments can be of technical and/or editorial nature.
Technical corrigendum: A corrected reprint of the current edition which is issued to correct
either a technical error or ambiguity in a Malaysian Standard inadvertently introduced either
in drafting or in printing and which could lead to incorrect or unsafe application of the
publication.
NOTE: Technical corrigenda are not to correct errors which can be assumed to have no consequences in the application
of the MS, for example minor printing errors.
STANDARDS MALAYSIA has appointed SIRIM Berhad as the agent to develop, distribute
and sell Malaysian Standards.
For further information on Malaysian Standards, please contact:
Department of Standards Malaysia OR SIRIM Berhad
Ministry of Science, Technology and Innovation (Company No. 367474 - V)
Level 1 & 2, Block 2300, Century Square 1, Persiaran Dato’ Menteri
Jalan Usahawan Section 2, P. O. Box 7035
63000 Cyberjaya 40700 Shah Alam
Selangor Darul Ehsan Selangor Darul Ehsan
MALAYSIA MALAYSIA
Tel: 60 3 8318 0002 Tel: 60 3 5544 6000
Fax: 60 3 8319 3131 Fax: 60 3 5510 8095
http://www.jsm.gov.my http://www.sirim.my
E-mail: [email protected] E-mail: [email protected]
MS 1837:2018
Contents
Page
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Foreword ..........................................................................................................................iv
1 Scope.......................................................................................................................... 1
2 Normative references................................................................................................... 1
3 Terms and definitions................................................................................................... 3
4 Abbreviations............................................................................................................... 8
5 General requirements .................................................................................................. 9
6 Protection requirements............................................................................................. 16
7 Wiring requirements................................................................................................... 19
8 Component requirements........................................................................................... 22
9 Earthing..................................................................................................................... 25
10 Marking requirements ................................................................................................ 25
11 Documentation .......................................................................................................... 27
12 Commissioning .......................................................................................................... 27
Annex A Characteristics of PV arrays ............................................................................. 30
Annex B Examples of signs ............................................................................................ 32
Annex C Maintenance requirements ............................................................................... 37
Bibliography ........................................................................................................................ 39
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Committee representation
The Industry Standards Committee on Generation, Transmission and Distribution of Energy (ISC E) under whose
authority this Malaysian Standard was developed, comprises representatives from the following organisations:
Association of Consulting Engineers Malaysia
Department of Standards Malaysia
Federation of Malaysian Manufacturers
Jabatan Kerja Raya Malaysia
Malaysia Nuclear Power Corporation
Malaysian Association of Standards Users
Malaysian Cable Manufacturers Association
Malaysian Electrical Appliances and Distributors Association
Malaysian Green Technology Corporation
Persatuan Kontraktor Elektrikal dan Mekanikal Melayu Malaysia
Sabah Electricity Sdn Bhd
Sarawak Energy Berhad
SIRIM Berhad (Secretariat)
SIRIM QAS International Sdn Bhd
Suruhanjaya Komunikasi dan Multimedia Malaysia
Suruhanjaya Tenaga
Sustainable Energy Development Authority Malaysia
Tenaga Nasional Berhad
The Electrical and Electronics Association of Malaysia
The Institution of Engineers, Malaysia
Universiti Malaya
The Technical Committee on Renewable Energies which supervised the development of this Malaysian Standard
consists of representatives from the following organisations:
Association of Consulting Engineers Malaysia
Bank Pembangunan Malaysia Berhad
Department of Environment
Felda Palm Industries Sdn Bhd
Forest Research Institute Malaysia
Independent
Jabatan Pengurusan Sisa Pepejal Negara
Malaysian Association of Standards Users
Malaysian Photovoltaic Industry Association
Sabah Electricity Sdn Bhd
Sarawak Energy Berhad
Sime Darby Plantation Sdn Bhd
SIRIM Berhad (Industrial Centre of Innovation - Energy management)
SIRIM Berhad (Secretariat)
Suruhanjaya Tenaga
Sustainable Energy Development Authority Malaysia
Tenaga Nasional Berhad
The Institution of Engineers, Malaysia
TNB Research Sdn Bhd
Universiti Teknologi MARA
Universiti Tenaga Nasional
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Committee representation (continued)
The Working Group on Solar Photovoltaic Systems which developed this Malaysian Standard consists of
representatives from the following organisations:
Jabatan Kerja Raya Malaysia
Malaysian Photovoltaic Industry Association
Malaysian Solar Resources
Manipal University
Sabah Electricity Sdn Bhd
Sarawak Energy Berhad
SIRIM Berhad (Industrial Centre of Innovation - Energy management)
SIRIM Berhad (Secretariat)
Suruhanjaya Tenaga
Sustainable Energy Development Authority Malaysia
The Electrical and Electronics Association of Malaysia
TNB Energy Services Sdn Bhd
TNB Research Sdn Bhd
Universiti Malaya
Universiti Teknologi Malaysia
Universiti Teknologi MARA
Universiti Tenaga Nasional
Universiti Tunku Abdul Rahman
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Foreword
This Malaysian Standard was developed by the Working Group on Solar Photovoltaic
Systems under the authority of the Industry Standards Committee on Generation,
Transmission and Distribution of Energy.
Major modifications in this revision are as follows:
a) incorporation of new requirement on “Scope” in Clause 1;
b) incorporation of new clauses on “Normative references” in Clause 2;
c) incorporation of new clauses on “Terms and definitions” in Clause 3;
d) incorporation of new clauses on “Abbreviations” in Clause 4;
e) incorporation of new figures on “General requirements” in Clause 5;
f) incorporation of new requirement on “Protection requirements” in Clause 6;
g) incorporation of new requirement on “Wiring requirements” in Clause 7;
h) incorporation of new requirement on “Component requirements” in Clause 8;
i) incorporation of new requirement on “Component requirements” in Clause 9;
j) incorporation of new requirement on “Marking requirements” in Clause 10;
k) incorporation of new requirement on “Commissioning” in Clause 12; and
l) incorporation of new figures in “Annex B”.
This Malaysian Standard cancels and replaces MS 1837:2010, Installation of grid-connected
photovoltaic (PV) system (First revision).
Compliance with a Malaysian Standard does not of itself confer immunity from legal
obligations.
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MS 1837:2018
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1 Scope
This Malaysian Standard sets out the general installation requirements for grid-connected
photovoltaic (PV) arrays with direct current (DC) open circuit voltages up to 1 500 V between
positive and negative conductors or up to ± 1 500 V with respect to earth.
NOTES:
1. This includes the following PV array configurations:
a) single string of modules;
b) multi-string PV array; and
c) PV array divided into several sub-arrays.
2. DC systems and photovoltaic systems in particular, pose some hazards in addition to those derived
from conventional alternate current (AC) power systems, including the ability to produce and sustain
electrical arcs with currents that are not much greater than normal operating currents. This standard
addresses the safety requirements arising from the particular characteristics of photovoltaic systems.
Those characteristics are presented in Annex A.
The objective of this standard is to provide guidelines on grid-connected PV system
installation, electrical safety and fire protection requirements for:
a) uninformed persons, including owner(s)/occupier(s) and users of the premises where
photovoltaic arrays are installed;
b) informed PV service providers and workers (e.g. electricians) working on these systems;
and
c) emergency workers.
2 Normative references
The following normative references are indispensable for the application of this standard. For
dated references, only the edition cited applies. For undated references, the latest edition of
the normative reference (including any amendments) applies.
MS 589 (series), Specification for 13 A plugs, socket-outlets, adaptors and connection units
MS 982, Specification for fire safety signs, notices and graphic symbols
MS 2558, Safety and health signage used in the workplace - Specification
MS IEC 60529, Degrees of protection provided by enclosures (IP code)
MS IEC 61000-6-3, Electromagnetic compatibility (EMC) - Part 6-3: Generic standards -
Emission standard for residential, commercial and light-industrial environments
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MS IEC 61000-6-4, Electromagnetic compatibility (EMC) - Part 6-4: Generic standards -
Emission standard for industrial environments
MS IEC 61215, Crystalline silicon terrestrial photovoltaic (PV) modules - Design qualification
and type approval
MS IEC 61643-12, Low voltage surge protective devices - Part 12: Surge protective devices
connected to low voltage power distribution systems - Selection and application principles
MS IEC 61646, Thin-film terrestrial photovoltaic (PV) modules - Design qualification and type
approval
IEC 60364-6, Low voltage electrical installations - Part 6: Verification
IEC 60364-7-712, Electrical installations of buildings - Part 7-712: Requirements for special
installations or locations - Solar photovoltaic (PV) power supply systems
IEC 61000-3-2, Electromagnetic compatibility (EMC) - Part 3-2: Limits - Limits for harmonic
current emissions (equipment input current ≤ 16 A per phase)
IEC 61215-1 (series), Terrestrial photovoltaic (PV) modules - Design qualification and type
approval - Part 1: Test requirements
IEC 61215-2, Terrestrial photovoltaic (PV) modules - Design qualification and type approval -
Part 2: Test procedures
IEC 61730-1, Photovoltaic (PV) module safety qualification - Part 1: Requirements for
construction
IEC 61730-2, Photovoltaic (PV) module safety qualification - Part 2: Requirements for testing
IEC 62305, Protection against lightning - ALL PARTS
IEC 62305-2, Protection against lightning - Part 2: Risk management
IEC 62305-3, Protection against lightning - Part 3: Physical damage to structures and life
hazard
IEC 62548, Photovoltaic (PV) arrays - Design requirements
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3 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
3.1 AC module
Combination of a PV module with an integrated micro inverter.
3.2 AC side
Part of the PV system from the AC terminals of the inverter until the grid connection to the
mains.
3.3 accessible, readily
Capable of being reached quickly and without climbing over or removing obstructions,
mounting upon a chair, or using a movable ladder, and in any case not more than 2.0 m
above the ground, floor or platform.
3.4 available, readily
Capable of being reached for inspection, maintenance or repairs without necessitating the
dismantling of structural parts, cupboards, benches or the like.
3.5 by-pass diode
Diode that is connected in parallel with a number of PV cells or the whole PV module.
3.6 cable
Single cable core, or two or more cable cores laid up together, either with or without fillings,
reinforcements, or protective coverings.
3.7 cable, shielded
Cable with surrounding earthed metallic layer to confine the electric field within the cable
and/or to protect the cable from external electrical influence.
NOTE. Metallic sheaths, armours and earthed concentric conductors may also serve as shields.
3.8 cable core
Conductor with its insulation but not including any mechanical protective covering.
3.9 Class II equipment
Equipment in which protection against electric shock does not rely on basic insulation only,
but in which additional safety precautions such as double insulation or reinforced insulation
are provided, there being no provision for protective earthing or reliance upon installation
conditions. Such equipment may be one of the following types:
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a) Equipment having durable and substantially continuous enclosures of insulating material
which envelops all metal parts, with the exception of small parts, such as nameplates,
screw and rivets, which are isolated from live parts by insulation at least equivalent to
reinforced insulation; such equipment is called insulation-encased Class II equipment.
b) Equipment having a substantially continuous metal enclosure, in which double insulation
is used throughout, except for those parts where reinforced insulation is used, because
the application of double insulation is manifestly impracticable; such equipment is called
metal-encased Class II equipment.
c) Equipment that is a combination of the types described in 3.9 a) and 3.9 b).
NOTES:
1. The enclosure of insulation-encased Class II equipment may form part of the whole of the
supplementary insulation or of the reinforced insulation.
2. If the equipment with double insulation or reinforced insulation throughout has an earthing terminal
or earthing contact, it is considered to be of Class I construction.
3. Class II equipment may be provided with means for maintaining the continuity of protective circuits,
insulated from accessible conductive parts by double insulation or reinforced insulation.
4. Class II equipment may have parts operating at SELV (separated extra low voltage).
3.10 connection box
Enclosure where cables are joined and/or connected to electrical equipment and/or protective
devices.
3.11 DC power optimiser
Module level DC-DC converter with maximum power point tracker (MPPT). Its role is to
extract optimum DC power from PV module.
3.12 DC side
Part of the PV system from the PV cell to the DC terminals of the inverter.
3.13 installation earthing
When a PV array is installed on a building, the installation earthing is the earthing bar or
earthing rod of the building.
3.14 inverter
System that converts the electrical power delivered by the PV array into the appropriate
frequency and/or voltage to be delivered to the load, and/or injected into the electricity grid.
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MS 1837:2018
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Short circuit current of a PV module or PV string at standard test conditions (STC), as
specified by the manufacturer on the product specification plate.
NOTE. As PV strings are a group of PV modules connected in series, the short circuit current of a string
is equal to ISC STC MOD.
3.16 ISC STC S-ARRAY
Short circuit current of a PV sub-array at STC, and is equal to:
ISC STC S-ARRAY = ISC STC MOD X NP SA
where
NP SA is the number of parallel-connected PV strings in the PV sub-array.
3.17 ISC ARRAY
Short circuit current of the PV array at STC, and is equal to:
ISC STC ARRAY = ISC STC MOD x NP A
where
NP A is the total number of parallel-connected PV strings in the PV array.
3.18 live part
Conductor or conductive part intended to be energised in normal use.
3.19 micro inverter
Inverter mounted on the back of or located very close to a PV module. Its role is to convert
the DC electricity produced by a single PV or by a combination of few, small capacity PV
modules into the appropriate AC electricity.
3.20 PARRAY STC
Nominal power of the PV array calculated as the sum of the nameplate power ratings of all
the PV modules that constitute the array.
3.21 PV array
Electrically integrated assembly of PV modules, and other necessary components, to form a
DC power supply unit. A PV array may consist of a single PV string, or several parallel-
connected strings, or several parallel-connected PV sub-arrays and their associated electrical
components. The boundary of a PV array is the connection of the PV array cable to a piece of
equipment that forms part of the inverter and which is dedicated to that particular PV array.
Two or more PV arrays, which are not interconnected in parallel on the generation side of the
inverter, is to be considered as independent PV arrays.
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3.22 PV array cable
Output cable of a PV array that connects the PV array connection box to the inverter.
3.23 PV array, isolated
PV array where there is electrical separation between the PV array output circuit and the AC
system.
NOTE. Electrical separation of power circuits is usually achieved by means of a power transformer.
3.24 PV array connection box
Enclosure where all the PV strings of a PV array or all the PV sub-arrays of a PV array are
electrically connected in parallel and where protection devices may be located, if necessary.
3.25 PV array open circuit voltage
PV array open circuit voltage is considered to be equal to VOC STC ARRAY (see 3.41).
NOTE. The open circuit voltage is dependent on the cell temperature.
3.26 PV cell
Basic unit of photovoltaic conversion; a semiconductor device that can convert light directly
into electrical energy.
3.27 PV kWh meter
kWh meter which records kWh units of AC electricity generated by a PV system.
3.28 PV module
Assembly of several PV cells electrically connected to form a larger photovoltaic conversion
device, and which are encapsulated together to protect them from the environment. A PV
module is the smallest ready-to-use photovoltaic conversion device.
3.29 PV module connection box
Enclosure affixed to a PV module, where the electrical connections to the PV module are
made.
3.30 PV string
Circuit formed by one or more series connected PV modules. The series connection of PV
modules to form a PV string is intended to provide the required circuit voltage.
3.31 PV string cable
Cable connecting the modules in a PV string, or connecting the string to a junction box or to
the DC terminals of the inverter.
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3.32 PV sub-array
Group of PV strings connected in parallel, that comprise a partial section of the PV array,
where the output current of that group of strings is carried by a dedicated output cable before
being connected in parallel with other sub-arrays.
NOTE. Not all PV arrays are divided into sub-arrays.
3.33 PV sub-array cable
Output cable of a PV sub-array that carries only the output current of its associated sub-array
in normal operation, and that connects the PV sub-array with the other PV sub-array that
constitute the PV array.
NOTE. PV sub-array cables are only relevant for PV arrays that are divided into sub-arrays.
3.34 PV sub-array connection box
Enclosure where all the PV strings of a PV are electrically connected in parallel and where
protection devices may be located if necessary.
NOTE. PV sub-array junction boxes are only relevant for PV arrays that are divided into sub-arrays.
3.35 PV system
Electrically integrated assembly of PV array, inverter (or power conditioning unit) and other
necessary components to form a power generation unit.
3.36 residual current device (RCD)
Device that instantly breaks an electric circuit to prevent serious harm from an ongoing
electric shock. RCD should be located close to point of interconnection and is accessible.
3.37 ripple-free DC
Sinusoidal ripple voltage, a ripple content not exceeding 10 % r.m.s.
NOTE. Therefore the maximum peak value does not exceed 140 V for a nominal 120 V ripple-free DC
system and 70 V for a nominal 60 V ripple-free DC system.
3.38 separated extra-low voltage (SELV)
Extra-low voltage system which is electrically separated from earth, and from other systems,
in such a way that a single fault cannot give rise to the risk of electric shock.
3.39 surge protective device
Device that is intended to limit transient over-voltages and divert surge currents. It contains at
least one non-linear component.
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MS 1837:2018
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Standard set of reference conditions used for the testing and rating of photovoltaic cells and
modules. The standard test conditions are:
a) PV cell temperature of 25 °C;
b) irradiance in the plane of the PV cell or module of 1 000 W/m2; and
c) light spectrum corresponding to an atmospheric air mass of 1.5.
3.41 VOC STC MOD
Open circuit voltage of a PV module at STC, as specified by the manufacturer in the product
specification.
3.42 VOC STC ARRAY
Open circuit voltage at STC of a PV array, and is equal to:
VOC STC ARRAY = VOC STC MOD x Ns
where
Ns is the number of series-connected PV modules in any PV string of the PV array.
NOTE. This standard assumes that all strings within a PV array are connected in parallel; hence the
open circuit voltage of PV sub-arrays and PV strings is equal to VOC STC ARRAY.
3.43 voltage
Differences of potential normally existing between conductors and between conductors and
earth are as follows:
a) extra-low voltage (ELV) - Not exceeding 50 V AC or 120 V ripple-free DC; and
b) low voltage (LV) - Exceeding extra-low voltage, but not exceeding 1 000 V AC or 1 500 V
DC.
NOTE. When calculating the voltage of a PV array, VOC STC ARRAY is to be used.
4 Abbreviations
MPPT maximum power point tracker
RCD residual current device
SPD surge protective device
STC standard test conditions
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MS 1837:2018
5 General requirements
The installation of a grid-connected PV system shall be in accordance with Figures 1 until 6.
These figures shall be extensively referred to throughout this standard.
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Circuit diagram w
Figure 1. Schematic diagram of a singl
with single MPPT inverter MS 1837:2018
le-phase grid-connected PV system with single MPPT inverter
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Circuit diagram w
Figure 2. Schematic diagram of a three-phase grid-co
with single MPPT inverter MS 1837:2018
onnected PV system with single MPPT inverter
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Circuit diagram with mu
Figure 3. Schematic diagram of a single-phase
ultiple MPPT inverter MS 1837:2018
grid-connected PV system with multiple MPPT inverter
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Circuit diagram with mu
ultiple MPPT inverter
MS 1837:2018
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Figure 4. Schematic diagram of a three-phase g
Circuit diagram
Figure 5. Schematic diagram of a single-phase
grid-connected PV system with multiple MPPT inverter MS 1837:2018
m with micro-inverter
grid-connected PV system with micro-inverter
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Circuit diagram with
Figure 6. Schematic diagram of a single-phase grid-
DC power optimiser MS 1837:2018
-connected PV system with DC power optimiser
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6 Protection requirements
6.1 General
The installation of grid-connected PV systems shall comply with the requirements of IEC
60364-7-712. The provisions of this section are aimed at ensuring that these requirements
are met, taking into account a range of system topologies and earthing arrangements.
6.2 By-pass diodes
In the case where by-pass diodes are needed but are not embedded in the PV module
encapsulation, they shall comply with all the following requirements:
a) have a voltage rating at least 2 x VOC STC MOD of the protected module;
b) have a current rating of at least 1.3 x ISC STC MOD;
c) be installed according to the module manufacturer’s recommendations;
d) be installed so no live parts are exposed; and
e) be protected from degradation due to environmental factors.
6.3 Over-current protection
6.3.1 Discrimination
Over-current protection within the PV string shall be graded in such a way that lower level
protection trips first in the event of fault currents flowing from higher current sections to lower
current sections of the PV array.
NOTE. When circuit breakers with over-current protection elements are used, they also provide the
disconnecting means required in 6.4.
6.3.2 PV strings
In cases where it applies (see Figures 1 until 6), all PV strings shall be protected with an over-
current protection device with load breaking disconnecting facilities. These over-current
protection devices shall be installed in positive active conductors. Strings overcurrent
protection shall be provided if more than two strings are connected to a single MPPT. Refer
IEC 62548.
The DC voltage rating and DC rated trip current (ITRIP) of over-current protection devices for
PV strings shall be as specified by the PV module manufacturer. In the case where they are
not specified the following formula shall be used:
For DC rated trip current: 1.5 x ISC STC MOD ITRIP 2 x ISC STC MOD
For the DC voltage rating: ≥1.2 x VOC STC ARRAY
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6.3.3 PV array and PV sub-arrays
Over-current protection device is not required for PV array and PV sub-arrays.
6.4 Disconnecting means
6.4.1 General
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array from the inverter and vice versa and to allow for maintenance and inspection tasks to be
carried out safely.
NOTES:
1. The PV array DC main switch shall be installed externally and closest to inverter.
2. This clause does not apply to AC module or micro inverters or where the inverter is an integral part
of the PV module.
6.4.2 Selection and installation
Only device with DC rating which is able to extinguish electrical arc shall be used.
Suitably rated circuit-breakers used for over-current protection may also provide load
breaking disconnecting facilities.
Other disconnection and isolation devices having the characteristics described in 8.4 may be
used as a disconnection means.
Fuse systems used for string over-current protection are acceptable non-load breaking
disconnecting means if they have removable fusing elements, preferably with a disconnection
mechanism (fuse-combination unit).
6.4.2.1 PV strings and PV sub-arrays
No separate disconnection device is required if suitably rated circuit-breakers are used for the
over-current protection which also provides load breaking disconnecting facilities.
6.4.2.2 PV array
A readily available load-breaking disconnection device, which interrupts both positive and
negative conductors, shall be installed in the PV array cable. This device shall be secured in
the off position.
6.4.2.3 Inverter
A suitably AC rated and readily available load-breaking disconnection device, which interrupts
both live and neutral conductors, shall be installed in the cable connected to the inverter AC
terminal. This device shall be secured in the off position.
6.5 Emergency switching device
The PV array (DC) load-breaking disconnection device and the inverter (AC) load-breaking
disconnection device shall be used as the emergency switching devices, and therefore shall
be readily accessible and be clearly identified.
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6.6 Earth fault protection
All metal casings and frames shall be earthed according to IEC 60364-7-712.
6.7 Lightning protection
Lightning protection measures may be required or modified in cases where it involves PV
installations. The need for lightning protection shall be assessed in accordance with
IEC 62305-2.
For ground mounted or freestanding PV arrays, the need for a lightning protection system
shall be assessed in accordance with IEC 62305-2, and if required, it shall be installed in
compliance with that standard.
The installation of a PV array on a building has a negligible effect on the probability of direct
lightning strikes and therefore it does not necessarily imply that a lightning protection system
shall be installed if none is already present. However, if the physical characteristics or
prominence of the building do change significantly due to the installation of the PV array, it is
required that the need for a lightning protection system be assessed in accordance with
IEC 62305-2, and if required, it shall be installed in compliance with that standard.
If a lightning protection system is already installed on the building, it shall be verified that the
PV array and associated equipment are within the protection zone of the system in
accordance with IEC 62305-3. If the PV array is not within the protection zone of the existing
lightning protection system, additional air termination(s) shall be provided in accordance with
IEC 62305-3.
When a PV array is protected by a lightning protection system, the metal structure of the PV
array shall be bonded to the lightning protection system, unless the minimum safety
clearances as specified in IEC 62305-3, can be achieved.
6.8 Over-voltage protection
Over-voltage protection measures include:
a) equipotential bonding;
b) avoidance of wiring loops;
c) installation of SPDs; and
d) shielding.
6.8.1 Wiring loops
To reduce the magnitude of lightning induced over-voltages, the PV array wiring shall be laid
in such a way that the area of conductive loops is minimum (see example in Figure 7).
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6.8.2 Surge protective device
Refer to MS IEC 61643-12.
6.8.3 Shielding
When the PV array frame is bonded to a lightning protection system, the PV array cable shall
be shielded by one of the following methods, and the shielding conductor shall be connected
to earth at both ends:
a) with a metallic cable armour or shield with an equivalent cross-sectional area of
10 mm2 Cu; or
b) with a metallic conduit suitable as a bonding conductor; or
c) with an equipotential bonding conductor with a cross-sectional area of at least 6 mm2 .
NOTE. 6 mm2 Cu should be able to withstand 20 kA for 1 ms.
7 Wiring requirements
7.1 Wiring standards
The PV systems shall be wired according to IEC 60364-7-712 requirement.
NOTE. Particular attention needs to be given to the protection of wiring systems against external
influences.
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7.2 System voltage
VOC STC ARRAY shall not exceed the maximum allowed system voltage of the PV modules (as
specified by the manufacturer).
7.3 Wiring installation
7.3.1 General
Wiring of PV arrays shall be laid in such a way that the possibility of line to line and line to
earth faults occurring is minimised.
All connections shall be verified for tightness and polarity during installation to reduce the risk
of faults and possible arcs occurring during commissioning and operation.
7.3.2 Wiring loops
The PV array wiring should be laid in such a way that the area of conductive loops is
minimised (e.g. by laying cables in parallel as shown in Figure 7).
7.3.3 String, sub-array and array wiring
The wiring of PV strings, sub-arrays and array shall satisfy the following requirements:
a) Double insulated, DC rated, UV resistant, flex type and fire retardant shall be used.
b) Cables shall be protected from mechanical damage.
c) Cables shall be clamped (to relieve tension and to prevent conductors coming free from
the connection).
7.3.4 Wiring installation in connection boxes
The following provisions apply to the installation of wiring systems in connection boxes:
a) Where conductors enter a connection box without conduit, a tension relief system shall be
used to avoid cable disconnections inside the connection box (for example, by using a
gland connector).
b) All cable entries, when installed, shall maintain the IP rating of the enclosure.
NOTE. Water condensation inside connection boxes may be a problem in some locations and
provision may need to be provided to drain water build-up.
c) The wiring and its insulation particularly through the connection box including terminal
points shall maintain double insulation status over its entire length.
7.3.5 Location of PV array and PV sub-array connection boxes
PV array and PV sub-array connection boxes, where installed, shall be readily available.
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7.4.1 Cable size
7.4.1.1 General
Cable sizes for PV string cables, PV sub-array cables and PV array cables shall not be less
than 2.5 mm2 and shall be determined with regard to both, the minimum current capacity (see
7.4.1.2) and maximum voltage drop requirements (see 7.4.1.3). The larger cable size
obtained from these two criteria shall be applied.
7.4.1.2 Current carrying capacity (CCC)
The minimum cable sizes for PV array wiring, based on CCC, shall be based upon a current
rating according to Table 1.
Table 1. Current rating of PV array circuits
Type of cable Minimum current upon which cable cross-sectional
area should be chosen
PV string cable 2 x ISC STC MOD
PV sub-array and array 1.3 x ISC STC S-ARRAY or ARRAY (of relevant array)
cable
NOTE. The operating temperature of PV modules and consequently their associated wiring can be
significantly higher than the ambient temperature. A minimum temperature rise above maximum
expected ambient temperature of + 40 C should be considered for cables installed near or in contact
with PV modules.
7.4.1.3 Voltage drop
The voltage drop between the PV array and the inverter shall be less than 3 %.
NOTE. Voltage drop in cables is a measure of the losses in PV array wiring, hence affects the efficiency
of the PV power system.
7.4.2 Insulation
The insulation of cables used within the PV array shall:
a) have a voltage rating of at least 1.2 x VOC STC ARRAY;
NOTE. The use of double insulated cable, and in the case if shielded cable is required, for wiring of
PV arrays, VOC STC ARRAY 120 V DC, to minimise the risk of faults within the wiring.
b) have a temperature rating according to the application; and
NOTE. PV modules frequently operate at temperatures of the order of 40 C above ambient
temperature. Cable insulation of wiring installed in contact with, or near, PV modules needs to be
rated accordingly.
c) be UV resistant, or be protected from UV light by appropriate protection (e.g. installed in
UV resistant conduit).
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7.5 Wiring identification
Appropriate identification shall be provided for PV array cabling where it can be confused with
other wiring systems.
7.6 Wiring insulation test
Wiring insulation test shall be carried out after each PV installation which shall follow the
methods described in IEC 60364-6.
8 Component requirements
8.1 PV modules
8.1.1 Reliability
PV modules shall comply with MS IEC 61215 or IEC 61215-1 (series) and IEC 61215-2.
In cases where PV modules are exposed to particular environmental conditions, standards
such as IEC 62716 and IEC 61701 shall apply.
8.1.2 Equipment class
PV modules shall be Class II. PV modules shall comply with IEC 61730-1 and IEC 61730-2.
8.1.3 Reverse current
PV modules shall be capable of conducting continuously a reverse current as per module
manufacturer.
8.2 Inverter requirements
Inverters shall comply with requirements in accordance to MS IEC 61000-6-3,
MS IEC 61000-6-4, IEC 60364-7-712, IEC 61000-3-2. Inverters shall be isolated in the event
of mains supply failure.
8.2.1 Maximum input voltage
The maximum input DC voltage at the lowest possible module temperature shall not exceed
the maximum input voltage of the inverter.
8.2.2 Operating voltage
The operating DC voltage shall be within the MPPT voltage range of the inverter.
8.2.3 Maximum input power
The maximum input power shall follow recommendations from the manufacturer.
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8.3.1 Environmental effects
PV array and PV sub-array connection boxes exposed to the environment shall be at least
IP 65 compliant in accordance with MS IEC 60529, and shall be UV resistant.
8.4 Switching devices
8.4.1 General
All switching devices shall comply with the following requirements:
a) be rated for AC side as AC and be rated for DC side as DC use and able to extinguish
electrical arcs;
b) have minimum rated current: 1.3 x ISC STC MOD;
c) have minimum rated voltage: 1.2 x VOC STC ARRAY;
d) do not have exposed metallic live parts in connected or disconnected state;
e) interrupt all poles; and
f) be independent and closest possible to the inverter(s) both for PV DC main switch, PV
DC switch(es) and PV AC switch(es).
8.4.2 Current breaking devices
In addition to the requirements of 8.4.1, circuit-breakers and any other load breaking
disconnection devices used for protection and/or disconnecting means shall comply with the
following requirements:
a) are not polarity sensitive (as fault currents in a PV array may flow in the opposite direction
of normal operating currents);
b) be rated to interrupt full load and prospective fault currents from the PV array and any
other connected power sources such as batteries, generators and the grid, if present; and
c) when over-current protection is incorporated, the trip current shall be rated according to
6.3.
8.4.3 Plugs, sockets and couplers
Plugs, sockets and couplers shall comply with all the following requirements:
a) be rated for AC side for AC use and be rated for DC side for DC use;
b) have a voltage rating greater than 1.2 x VOC STC ARRAY ;
c) be protected from contact with live parts in both the connected and disconnected state
(i.e. be shrouded);
d) have a current rating equal to, or greater than, the cable to which they are fitted;
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e) require a deliberate force to disconnect;
f) have a temperature rating suitable for their installation location;
g) if multipolar, be polarised;
h) comply with Class II; and
i) if exposed to the environment, be rated for outdoor use, be UV resistant and be at least
IP 65 compliant.
Plugs and socket outlets normally used for connection to AC mains power as described in
MS 589 (series) shall not be used in PV arrays wiring.
8.5 Fuses
Fuses used in PV arrays shall comply with all the following requirements:
a) be rated for AC for AC use and be rated for DC for DC use;
b) have a voltage rating equal to, or greater than 1.2 x VOC STC ARRAY;
c) be rated to interrupt full load and prospective fault currents from the PV array and
connected power sources such as batteries, generators and the grid, if present; and
d) for rated trip current: 1.5 x ISC STC MOD ITRIP 2 x ISC STC MOD.
NOTE. When fuses are provided for over-current protection, the use of fused load break switch-
disconnectors (fuse-combination units) is recommended.
8.5.1 Fuse holders
Fuse holders shall comply with all the following requirements:
a) have a voltage rating equal to, or greater than open circuit string voltage;
b) have a current rating equal to, or greater than, the corresponding fuse; and
c) provide a degree of protection not less than IP 2X.
8.6 PV kWh meter
The PV kWh meter is used to record kWh units of AC generated electricity by a PV system.
The meter shall be connected between the AC switch and the AC grid isolator main switch
(AC load breaking disconnection device).
The PV kWh meter shall be suitable to record kWh units of AC electricity. The meter shall
comply with the requirements of the local regulatory body (ies).
8.7 Operating temperatures
The operating temperatures of all components shall follow the manufacturer specifications.
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9.1 General
There are three possible reasons for earthing a PV array:
a) to achieve equipotential bonding to avoid uneven potentials across ground installation;
b) to provide a path for fault currents to flow; and
c) to provide lightning protection.
An earth conductor may perform one or more of these functions in an installation. The
dimensions and location of the conductor are very dependent on its function.
9.2 Earthing electrode
If a separate earthing electrode is provided for the PV array, this electrode shall be bonded to
the installation earthing.
9.3 Equipment earthing
9.3.1 Earthing of module
Earthing PV modules shall comply with manufacturer’s requirement.
9.3.2 Earthing of equipment
Equipment earthing refers to the bonding to earth of inverters and all metal parts including
structural metalwork. Equipment earthing shall be done with at least a 10 mm2 earthing
conductor.
9.3.3 Earthing conductors
All PV array earthing conductors shall comply with the material, type, identification, installation
and connection requirements as specified in IEC 62305-3.
10 Marking requirements
10.1 General
All signs required by 10.2 to 10.5 shall:
a) comply with MS 982 and MS 2558;
b) be indelible;
c) be legible from at least 0.8 m unless otherwise specified in the relevant clauses; and
d) be constructed and affixed to remain legible for the life of the equipment it is attached or
related to.
NOTE. Examples of signs are given in Annex B (see Figure B.1 to B.9).
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10.2 PV array and PV sub-array connection boxes
A sign containing the text 'PV DC' shall be attached to PV array and PV sub-array connection
boxes.
10.3 Disconnection devices
10.3.1 General
Disconnection devices shall be marked with an identification name or number in accordance
with the PV array wiring diagram.
All switches shall have the ON and OFF positions clearly indicated.
10.3.2 PV DC main switch
10.3.2.1 PV array DC main switch
The PV DC main switch (DC load breaking disconnection device) shall be provided with a
sign affixed in a prominent location with the following text: ‘PV DC MAIN SWITCH’ (see
Figure B.1).
10.3.2.2 PV DC switch
The PV DC switch (DC load breaking disconnection device) shall be provided with a sign
affixed in a prominent location with the following text: ‘PV DC SWITCH’ (see Figure B.2).
10.3.3 Inverter switch
The inverter switch (AC load breaking disconnection device) shall be provided with a sign
affixed in a prominent location with the following text: ‘PV AC SWITCH’ (see Figure B.3).
10.3.4 PV AC main switch
The PV AC main switch (AC load breaking disconnection device) shall be provided with a sign
affixed in a prominent location with the following text: ‘PV AC MAIN SWITCH’ (see Figure B.4).
10.4 Fire emergency information
10.4.1 General
For PV arrays that are installed on buildings and have a rated power greater than 500 W or
with VOC STC ARRAY greater than 50 V, a sign next to the building main switchboard shall be
provided. This sign shall specify the procedure for the fire brigade to enter the building without
the risk of electric shock from the PV array and the operation of the emergency switching
device, if relevant. This sign shall be legible from at least 1.5 m. The signage see Figure B.5.
10.4.2 Manually operated emergency switching device
When a manually operated switching device is used, the means of operating such device,
such as handles or push-buttons for emergency switching, shall be clearly indicated. The
signs to identify the switching devices (see 10.3.2 to 10.3.4) shall be placed next to them and
shall be legible from at least 1.5 m.
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A sign, that contains shutdown instructions for the PV system, shall be located in a prominent
location. The sign shall include the name and location of the relevant disconnection devices.
The sign shall also include the following PV array information:
a) open circuit voltage at STC; and
b) short circuit current at STC.
11 Documentation
The PV system installer shall prepare the following documents and a copy shall be handed to
the PV system owner:
a) a basic circuit diagram that includes the electrical ratings of the PV array, including the
information required by 10.4;
b) a copy of the emergency shutdown procedure including the location of relevant switching
devices;
c) as-built drawing that includes the PV array, the inverter and the major components;
d) PV system or parts certification as required by relevant authorities and provided by
manufacturer;
e) all specifications of the PV array, the inverter and the system components; and
f) PV system maintenance requirements (see Annex C).
12 Commissioning
12.1 General
Commissioning tests are required to ensure that the PV system complies with the safety
requirements of this standard and the requirement of the local authority (ies).
12.2 Wiring and installation integrity
The PV array wiring shall be inspected for compliance with the wiring requirements of
IEC 60364-7-712, and the wiring requirements Clause 7 and corrected if necessary.
12.3 Open circuit voltage
12.3.1 General
This test is intended to ensure that wiring polarity and continuity of the PV array are correct.
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12.3.2 Procedure
The open circuit voltage of every string shall be measured before connecting to other strings.
All PV string open circuit voltages shall be within 5 % variation; otherwise the connections
shall be verified for polarity, continuity and possible faults and repaired. Once the verification
is complete and satisfactory, the PV strings can be connected in parallel.
The same procedure shall be carried out to verify PV sub-array open circuit voltages (if
relevant) and PV array open circuit voltage before connecting the PV array to the inverter.
NOTE. It is recommended that all measurements are made under irradiance conditions (during the
daytime with no rain).
12.4 Short circuit current
12.4.1 General
This test is intended to ensure that the module is performing as per manufacturer
specification and design.
12.4.2 Procedure
The short circuit current of every string shall be measured before connecting to other strings.
All PV string short circuit current shall be within 5 % variation; otherwise the connections shall
be verified for performance, continuity and possible faults and repaired. Once the verification
is complete and satisfactory, the PV strings can be connected in parallel.
NOTE. It is recommended that all measurements are made under irradiance conditions of at least
350 Wm-2 (during the daytime with no rain).
12.5 PV kWh meter
The meter shall be tested for functionality and the initial value shall be recorded.
12.6 Commissioning records
The following commissioning records shall be given to the owner, and if necessary to the
relevant authorities:
a) a certificate stating that the work done on the installation meets the requirements of this
standard;
b) a record of the final open circuit voltage measurements;
c) a record of the short circuit current measurements;
d) a record of cable insulation test for all DC and AC cables;
e) a record of the acceptance test of power for each inverter (where applicable);
f) a record of the performance ratio test of the system;
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g) a record measured values of current and/or resistance before and after any adjustments
to the earth fault protection system (if relevant); and
h) a record of the initial value of the PV kWh meter.
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Annex A
(informative)
Characteristics of PV arrays
A.1 PV arrays
A.1.1 DC versus AC behavior
One of the most important characteristics of direct current (DC) in relation to safety is that DC
arcs, caused by switching or faults, are much more difficult to extinguish than AC arcs. This
implies that all switchgear and over-current protection devices in the PV array need to be
rated for use in DC circuits (DC switchgear is less readily available and its cost increases
significantly, as the DC operating voltages increase).
A.1.2 Series parallel configuration
To reduce mismatch and improve PV array yield, all PV strings within a PV array should be of
the same technology and have the same number of series connected PV modules. Also, all
PV modules within the PV array should have similar rated electrical characteristics including
short circuit current, open circuit voltage, maximum power current, maximum power voltage
and rated power (all at STC).
A.1.3 Low fault levels
PV cells (and consequently PV arrays) behave like current sources under low impedance
faults. Thus, in PV arrays without battery storage, currents much greater than normal full load
currents will not flow even under short circuit fault conditions, making short circuit detection
impossible. Therefore, electric arcs can be formed in a PV array with fault currents that will
not trip an over-current device. The implications for PV array design that arise from these PV
array characteristics are:
a) the chances of line to line faults, earth faults and inadvertent wire disconnections in the
system need to be minimised; and
b) earth fault detection and disablement could be required as part of the system protection
functions depending on the array size and location, to eliminate the risk of fire.
A.1.4 Operating temperature
PV modules can operate well above ambient temperature under normal operating conditions.
A common steady state temperature rise for silicon modules operating at the maximum power
point under 1 000 W/m2 solar irradiance and with adequate ventilation is 25 C. This
temperature rise can go up by 35 C when modules are open circuited (i.e. the PV array has
been put out of operation due to grid failure in the case of grid connected systems). The
temperature rise can be even higher when irradiance levels are greater than 1 000 W/m2 and
when modules have poor ventilation. The following are two main requirements on the PV
array design derived from this operating characteristic of PV modules:
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a) PV module efficiency reduces as their operating temperature increases (for crystalline
silicon solar cells the maximum power decreases between 0.4 % and 0.5 % per each
degree C rise in operating temperature). Therefore, adequate ventilation of the PV array
should be a design goal, in order to ensure optimum performance for both modules and
associated components.
b) All the components and equipment that may be in direct contact or near the PV array
(conductors, inverters, connectors, etc.) need to be capable of withstanding the expected
maximum operating temperature of the PV array.
A.2 Grid-connected photovoltaic (PV) systems
The systems have the following characteristics.
a) Generally, grid-connected photovoltaic (PV) systems do not use batteries for energy
storage because the grid behaves as an infinite bus that can receive or supply power.
b) PV arrays in these systems tend to be low voltage.
c) A wide range of inverter topologies can be found on the market. Some include an
isolation transformer, some are transformer less; some require the PV array to be earthed
and some require it not to be earthed.
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Annex B
(informative)
Examples of signs
B.1 Overview
This annex provides examples of appropriate signs as specified in Clause 10.
PV DC
MAIN SWITCH
Figure B.1. Example of sign required on PV DC main switch connection box
PPVVDDCC
MAISNWSIWTCITHCH
Figure B.2. Example of sign required adjacent to PV DC switch
PV AC
SWITCH
Figure B.3. Example of sign required adjacent to inverter main switch
PV AC MAIN
SWITCH
Figure B.4. Example of sign required adjacent to PV AC main switch
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THIS PREMISE IS
INSTALLED WITH SOLAR
PV SYSTEM
Figure B.5. Signage for metering area
FIRE EMERGENCY
INFORMATION
DISCONNECT ALL PV
SWITCHES
FOLLOW THE PV SYSTEM
SHUTDOWN PROCEDURE
Figure B.6. Signage for metering area
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PROCEDURE
STEP 1: Turn off the ‘PV AC MAIN
SWITCH’ located next to the PV
meter.
STEP 2: Turn off all ‘PV AC SWITCHES’
located next to the AC terminals
of the inverter.
STEP 3: Turn off all ‘PV DC SWITCHES’
located next to the DC terminals
of the inverter.
Warning:
Do not disconnect any fuses or
connectors during operation
PV Array Open Circuit Voltage at STC: VDC
PV Array Short Circuit Current at STC: ADC
Figure B.7. Signage for string inverter shutdown procedure
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PV SYSTEM SHUTDOWN
PROCEDURE
STEP 1: Turn off the ‘PV AC MAIN
SWITCH’ located next to the PV
meter.
STEP 2: Turn off all ‘PV AC SWITCHES’
located next to the AC terminals
of the inverter.
STEP 3: Turn off all ‘PV DC SWITCHES’
located next to the DC terminals
of the inverter.
Warning:
Do not disconnect any fuses or
connectors during operation
Maximum PV Array AC Voltage (ON condition):________Vac
Maximum PV Array AC Voltage (OFF condition):________Vac
Maximum PV Array AC Current (ON condition):________Aac
Figure B.8. Signage for micro inverter shutdown procedure
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PV SYSTEM SHUTDOWN
PROCEDURE
STEP 1: Turn off the ‘PV AC MAIN
SWITCH’ located next to the PV
meter.
STEP 2: Turn off all ‘PV AC SWITCHES’
located next to the AC terminals
of the inverter.
STEP 3: Turn off all ‘PV DC SWITCHES’
located next to the DC terminals
of the inverter.
Warning:
Do not disconnect any fuses or
connectors during operation
Maximum PV Array DC Voltage (ON condition):________Vdc
Maximum PV Array DC Voltage (OFF condition):________Vdc
Maximum PV Array DC Current (ON condition):________Adc
Figure B.9. Signage for DC power optimiser shutdown procedure
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Annex C
(informative)
Maintenance requirements
C.1 Safety
Attention should be given in the maintenance procedures to the following safety requirements:
a) follow emergency shutdown procedure;
b) obey all warning signs;
c) shut system down and interrupt PV array according to the manual shutdown procedure;
d) split strings into extra low voltage sections (if relevant); and
e) warn of the live parts that cannot be de-energised during daylight.
C.2 Periodic maintenance
The following maintenance activities should be considered for inclusions in the maintenance
procedures, according to the location, size and design of the PV array.
a) Cleaning of the PV array might be periodically required in locations where it is likely to
collect dust or other shading materials.
b) Periodic inspections should be carried out to check wiring integrity, electrical connections,
corrosion and mechanical protection of wiring.
c) Verify open circuit voltage, and if possible short circuit current values.
d) Verify functioning of earth fault protection (if relevant).
e) Measure wet insulation resistance.
f) Check PV array mounting structure(s).
g) Test operation of switches regularly.
h) Check for module defects (fracture, moisture penetration, browning, etc.).
i) Verify status of SPDs (if relevant).
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C.3 Operation and maintenance procedures
Operation and maintenance procedures should include the following:
a) a short description of the function and operation of all installed equipment. More detailed
information should be available from the manufacturer’s documentation [see C.3 d)];
b) emergency and maintenance shutdown procedures;
c) periodic maintenance requirements including procedures and schedule; and
d) equipment manufacturer’s documentation (data sheets, handbooks, etc.) for all
equipment supplied.
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