SIST EN IEC 62938:2020
(Main)Non-uniform snow load testing for photovoltaic (PV) modules
Non-uniform snow load testing for photovoltaic (PV) modules
This document provides a method for determining how well a framed PV module performs
mechanically under the influence of inclined non-uniform snow loads. This document is
applicable for framed modules with frames protruding beyond the front glass surface on the
lower edge after intended installation and as such creates an additional barrier to snow sliding
down from modules. For modules with other frame constructions, such as backrails formed in
frames, on the side edges, on the top edge and on the lower edge not creating an additional
snow slide barrier, this document is not applicable.
The test method determines the mechanical non-uniform-load limit of a framed PV module.
The loads specified in this document apply exclusively to natural snow load distributions. Any
expected artificial accumulations (e.g. from snow removal or redistribution) are considered
separately.
Methods to eliminate or counteract the occurence of inhomogeneous snow accumulation, such
as a steep installation angle (more than 60°), are not included in this document. This document
assumes a relationship between ground snow-cover and module snow-cover which may not be
applicable in locations where the snow does not completely melt between snow falls. This
document does not consider the effect of snow cover on power generation.
While the test method includes a wait time between load steps, the document does not provide
a complete assessment of the fatigue behaviour of the materials of the module, such as front
glass.
Because typical field failures of PV modules caused by snow load show glass breakage and
frame bending, the test method aims at reproducing the load under which such failures occur.
Ungleichmäßige Schneelastprüfung von Photovoltaikmodulen
Modules photovoltaïques (PV) - Essais de charges de neige non uniformes
l'IEC 62938:2020 fournit une méthode pour déterminer le comportement mécanique d'un module photovoltaïque (PV) encadré sous l'effet de charges de neige non uniformes. Le présent document s'applique aux modules encadrés dont les cadres dépassent de la façade vitrée avant au niveau du rebord inférieur lorsqu'ils se trouvent dans la position de montage prévue, ce qui crée une barrière supplémentaire contre les glissements de neige accumulée sur les modules. Le présent document ne s'applique pas aux modules reposant sur d'autres constructions de cadre, par exemple les rails arrière qui sont mis en œuvre dans les cadres, sur les rebords latéraux, sur le rebord supérieur et sur le rebord inférieur, mais qui n'empêchent pas les glissements de neige. La méthode d'essai détermine la limite mécanique d'un module photovoltaïque encadré aux charges de neige non uniformes.
Obremenilni preskus fotonapetostnih (PV) modulov pri neenakomerni snežni odeji
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN IEC 62938:2020
01-oktober-2020
Obremenilni preskus fotonapetostnih (PV) modulov pri neenakomerni snežni odeji
Non-uniform snow load testing for photovoltaic (PV) modules
Ta slovenski standard je istoveten z: EN IEC 62938:2020
ICS:
27.160 Sončna energija Solar energy engineering
SIST EN IEC 62938:2020 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN IEC 62938:2020
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SIST EN IEC 62938:2020
EUROPEAN STANDARD EN IEC 62938
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2020
ICS 27.160
English Version
Photovoltaic (PV) modules - Non-uniform snow load testing
(IEC 62938:2020)
Modules photovoltaïques (PV) - Essais de charges de neige Ungleichmäßige Schneelastprüfung von
non uniformes Photovoltaikmodulen
(IEC 62938:2020) (IEC 62938:2020)
This European Standard was approved by CENELEC on 2020-06-18. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
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. EN IEC 62938:2020 E
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SIST EN IEC 62938:2020
EN IEC 62938:2020 (E)
European foreword
The text of document 82/1670/FDIS, future edition 1 of IEC 62938, prepared by IEC/TC 82 "Solar
photovoltaic energy systems" was submitted to the IEC-CENELEC parallel vote and approved by
CENELEC as EN IEC 62938:2020.
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2021-03-18
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2023-06-18
document have to be withdrawn
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.
Endorsement notice
The text of the International Standard IEC 62938:2020 was approved by CENELEC as a European
Standard without any modification.
2
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SIST EN IEC 62938:2020
EN IEC 62938:2020 (E)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available here:
www.cenelec.eu.
Publication Year Title EN/HD Year
IEC/TS 60904-13 2018 Photovoltaic devices - Part 13: - -
Electroluminescence of photovoltaic
modules
IEC 61215-1 2016 Terrestrial photovoltaic (PV) modules - EN 61215-1 2016
Design qualification and type approval -
Part 1: Test requirements
IEC 61215-2 2016 Terrestrial photovoltaic (PV) modules - EN 61215-2 2017
Design qualification and type approval -
Part 2: Test procedures
EN 61215-2:2017/AC 2017-
07
IEC/TS 61836 - Solar photovoltaic energy systems - - -
Terms, definitions and symbols
IEC/TS 62915 - Photovoltaic (PV) modules - Type - -
approval, design and safety qualification -
Retesting
3
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SIST EN IEC 62938:2020
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SIST EN IEC 62938:2020
IEC 62938
®
Edition 1.0 2020-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Photovoltaic (PV) modules – Non-uniform snow load testing
Modules photovoltaïques (PV) – Essais de charges de neige non uniformes
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.160 ISBN 978-2-8322-8074-4
Warning! Make sure that you obtained this publication from an authorized distributor.
Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
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SIST EN IEC 62938:2020
– 2 – IEC 62938:2020 IEC 2020
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Sampling . 6
5 Prerequisites . 7
6 Testing . 7
6.1 General . 7
6.2 Projections of the test results . 7
6.3 Test plan . 7
7 Test procedures . 9
7.1 Visual inspection . 9
7.2 Maximum power determination . 9
7.3 Insulation test . 9
7.4 Wet leakage current test . 9
7.5 Humidity-freeze test . 9
7.6 Electroluminescence imaging . 9
7.7 Non-uniform snow load test . 9
7.7.1 Purpose . 9
7.7.2 Load specification . 9
7.7.3 Apparatus . 11
7.7.4 Procedure . 13
8 Fail criteria . 15
9 Verification of the test results . 15
10 Statistical analysis . 15
10.1 General . 15
10.2 5 % fractile value with Student's distribution . 16
10.3 Safety factor . 16
10.4 Example. 16
10.5 Quantiles of the t distribution (Student's distribution) . 16
11 Test report . 17
12 Modifications . 18
Annex A (informative) Use of determined values . 19
A.1 Estimated snow loads and use of the determined resistance . 19
A.2 Calculate the bearable loads for different angles . 19
Bibliography . 20
Figure 1 – Test plan for inhomogeneous snow load test . 8
Figure 2 – Distribution of load on the test specimen at inclination . 10
Figure 3 – Simplified cross-sectional view of module width along bottom frame . 12
Figure 4 – Test procedure for the snow load test . 14
Figure 5 – Different deflection graphs under static load . 14
Table 1 – Applicable load in relation to angle of pitch of roof . 10
Table 2 – Quantiles of the t distribution (Student's distribution) . 17
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SIST EN IEC 62938:2020
IEC 62938:2020 IEC 2020 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC (PV) MODULES –
NON-UNIFORM SNOW LOAD TESTING
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence between
any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62938 has been prepared by IEC technical committee 82: Solar
photovoltaic energy systems.
The text of this International Standard is based on the following documents:
FDIS Report on voting
82/1670/FDIS 82/1705/RVD
Full information on the voting for the approval of this International Standard can be found in the
report on voting indicated in the above table.
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
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SIST EN IEC 62938:2020
– 4 – IEC 62938:2020 IEC 2020
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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SIST EN IEC 62938:2020
IEC 62938:2020 IEC 2020 – 5 –
PHOTOVOLTAIC (PV) MODULES –
NON-UNIFORM SNOW LOAD TESTING
1 Scope
This document provides a method for determining how well a framed PV module performs
mechanically under the influence of inclined non-uniform snow loads. This document is
applicable for framed modules with frames protruding beyond the front glass surface on the
lower edge after intended installation and as such creates an additional barrier to snow sliding
down from modules. For modules with other frame constructions, such as backrails formed in
frames, on the side edges, on the top edge and on the lower edge not creating an additional
snow slide barrier, this document is not applicable.
The test method determines the mechanical non-uniform-load limit of a framed PV module.
The loads specified in this document apply exclusively to natural snow load distributions. Any
expected artificial accumulations (e.g. from snow removal or redistribution) are considered
separately.
Methods to eliminate or counteract the occurence of inhomogeneous snow accumulation, such
as a steep installation angle (more than 60°), are not included in this document. This document
assumes a relationship between ground snow-cover and module snow-cover which may not be
applicable in locations where the snow does not completely melt between snow falls. This
document does not consider the effect of snow cover on power generation.
While the test method includes a wait time between load steps, the document does not provide
a complete assessment of the fatigue behaviour of the materials of the module, such as front
glass.
Because typical field failures of PV modules caused by snow load show glass breakage and
frame bending, the test method aims at reproducing the load under which such failures occur.
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.
IEC TS 60904-13 :2018, Photovoltaic devices – Part 13: Electroluminescence of photovoltaic
modules
IEC 61215-1:2016, Terrestrial photovoltaic (PV) modules – Design qualification and type
approval – Part 1: Test requirements
IEC 61215-2:2016, Terrestrial photovoltaic (PV) modules – Design qualification and type
approval – Part 2: Test procedures
IEC TS 61836, Solar photovoltaic energy systems – Terms, definitions and symbols
IEC TS 62915, Photovoltaic (PV) modules – Type approval, design and safety qualification –
Retesting
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SIST EN IEC 62938:2020
– 6 – IEC 62938:2020 IEC 2020
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC TS 61836 and the
following 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 http://www.iso.org/obp
3.1
characteristic snow load
S
K
characteristic value of snow on the ground
2
Note 1 to entry: S is expressed in kN/m .
k
2
Note 2 to entry: The lowest value for S used in this document is 2,4 kN/m .
k
3.2
characteristic value of snow load
angle dependent snow load
S
A
product of the characteristic snow load on the ground and the snow load shape coefficient
2
Note 1 to entry: The lowest value for S used in this document is 1,47 kN/m .
A
3.3
snow load shape coefficient
µ
i
ratio of the snow load on the roof or PV module to the undrifted snow load on the ground
3.4
specific snow weight
γ
weight per unit volume of snow
3
Note 1 to entry: The specific snow weight γ is considered to be 3 kN/m .
3.5
snow load of the overhang
S
E
load vertical to the eaves applied in addition to the uniform load on a roof
3.6
fractile value
lower or upper bounds of a distribution function (Student's distribution, normal distribution, log
normal distribution, etc.) which represents, in construction, strenghts or impacts
4 Sampling
At least seven PV modules are used for testing. Five or more modules are used to determine
the maximum load bearing; one is used for determination of electrical degradation at a load
below the determined maximum load bearing and one is used as a control module.
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SIST EN IEC 62938:2020
IEC 62938:2020 IEC 2020 – 7 –
5 Prerequisites
The PV module type shall have passed the static mechanical load test (MQT 16) according to
IEC 61215-2 with a minimum positive test load of 5 400 Pa.
6 Testing
6.1 General
These test specifications describe a test method for determining the direct load-bearing
capability of framed PV modules under the effects of inhomogeneous snow loads.
6.2 Projections of the test results
Failure of the (adhesive) bond between module frame and glass/laminate can lead to
• deformation of the module rail or frame,
• glass breakage,
• displacement of rail or frame parts,
• fracture of rail or frame parts,
• loss of adh
...
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