|
IEC TR 63225
Edition 1.0 2019-11
TECHNICAL
REPORT
Incompatibility of connectors for DC-application in photovoltaic systems
your local IEC member National Committee for further information.
IEC Central Office Tel.: +41 22 919 02 11
3, rue de
CH-1211 Geneva 20
Switzerland
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.
About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigendum or an amendment might have been published.
IEC publications search - webstore.iec.ch/advsearchform Electropedia - www.electropedia.org
The advanced search enables to find IEC publications by a The world's leading online dictionary on electrotechnology,
variety of criteria (reference number, text, technical containing more than 22 000 terminological entries in English
committee,…). It also gives information on projects, replaced and French, with equivalent terms in 16 additional languages.
and withdrawn publications. Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Just Published - webstore.iec.ch/justpublished
Stay up to date on all new IEC publications. Just Published IEC Glossary - std.iec.ch/glossary
details all new publications released. Available online and 67 000 electrotechnical terminology entries in English and
once a month by email. French extracted from the Terms and Definitions clause of
IEC publications issued since 2002. Some entries have been
IEC Customer Service Centre - webstore.iec.ch/csc collected from earlier publications of IEC TC 37, 77, 86 and
If you wish to give us your feedback on this publication or CISPR.
need further assistance, please contact the Customer Service
.
IEC TR 63225
Edition 1.0 2019-11
TECHNICAL
REPORT
Incompatibility of connectors for DC-application in photovoltaic systems
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-7534-4
– 2 – IEC TR 63225:2019 © IEC 2019
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Background . 5
5 Observations . 7
6 Affected stakeholders . 7
7 Proposed course of action . 8
7.1 General . 8
7.2 Long-term aim . 8
7.3 Interim measures . 8
8 Conclusion . 9
Bibliography . 10
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INCOMPATIBILITY OF CONNECTORS FOR
DC-APPLICATION IN PHOTOVOLTAIC SYSTEMS
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.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a Technical Report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 63225, which is a Technical Report, has been prepared by IEC technical committee 82:
Solar photovoltaic energy systems.
The text of this Technical Report is based on the following documents:
Draft TR Report on voting
82/1499/DTR 82/1552A/RVDTR
Full information on the voting for the approval of this Technical Report 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.
– 4 – IEC TR 63225:2019 © IEC 2019
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.
A bilingual version of this publication may be issued at a later date.
INCOMPATIBILITY OF CONNECTORS FOR
DC-APPLICATION IN PHOTOVOLTAIC SYSTEMS
1 Scope
This document highlights the problem of incompatibility of connectors for DC-application in
photovoltaic systems (DC connectors) produced by different manufacturers. It addresses four
particular issues in that context:
• background information on incompatibility of DC connectors from different manufacturers;
• observations and challenges concerning the handling of DC connectors from different
manufacturers;
• stakeholders concerned by the incompatibility of DC connectors;
• recommendations for long-term standardization and interim measures to address
incompatibility of DC connectors.
2 Normative references
IEC 62852, Connectors for DC-application in photovoltaic systems – Safety requirements and
tests
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 62852 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
DC connector
connector designed for use in DC circuits of photovoltaic systems, as defined in IEC 62852.
Note 1 to entry: This document generally refers to connectors of type MC4 or similar, and particularly products that
are often referred to as “MC4-compatible”.
3.2
compatible DC connectors
interoperable DC connectors
intermateable DC connectors
components which terminate conductors for the purpose of providing
connection to and disconnection from a suitable mating component under supervision of one
quality management system
4 Background
In the early years of terrestrial photovoltaics, a range of different DC connectors were available
on the market. They were of distinctly different designs and could not be connected between
– 6 – IEC TR 63225:2019 © IEC 2019
each other. In the early 2000s the connector type MC4 became more and more popular.
Manufacturers started to adapt their connectors to the MC4 type. However, no international or
consortia-based interface technical specifications for this connector type are available.
IEC 62852, often referred to in this context, is a product safety standard and is not intended to
test intermateability.
Several countries report that problems with DC connectors are a major cause for failure such
as fire hazards in PV systems. Reports from different testing laboratories have shown that DC
connectors from different manufacturers may not be safe to interconnect. Even if they meet
basic quality requirements in the short term, they may derate when connected to products from
different manufacturers.
Disregarding these circumstances, DC connectors are often declared by manufacturers as
being compatible with each other. This claim of compatibility is potentially misleading as it
suggests a safe interoperability of DC connectors from different manufacturers.
The reasons for the incompatibility of DC connectors from different manufacturers over the
intended lifetime of the connectors are as follows.
• Different metal alloys are used. This results in a high risk of increased resistance between
the DC connectors, for example because of contact corrosion and/or thermal expansion
differences.
• Different contact designs are used. This results in a high risk of increased resistance.
• Mechanical tolerances are not specified. This can lead to both material stress and loose
contacts risking an increased resistance between the DC connectors. This increased
resistance can also result from products under the same quality management system over
the intended lifetime of the connectors if the tolerances are not sufficiently defined by the
manufacturer.
• The material used for the polymeric parts of the DC connector is not specified. This creates
a risk of chemical incompatibility and different thermal expansion behaviour resulting in
accelerated ageing of the components and increased resistance, and exacerbating the
points previously mentioned during long-term implementation on a PV installation. In
addition, degradation and corrosion of the polymeric parts from external factors is a risk that
could lead to ingress of dust and water.
• Even if a pair of connectors from different manufacturers have been declared compatible at
one point in time, the quality management system or materials used by one brand might
change in the interim, meaning that later batches of the same connector are in fact no longer
compatible.
IEC 61730-1 tackles the safe electrical operation of PV modules, but does not tackle the topic
of connecting DC connectors from different manufacturers. However, IEC 62548 and
IEC 60364-7-712:2017 are installation standards and they explicitly do not allow the connection
of DC connectors from different manufacturers. IEC 62852 is not intended to be used for DC
connectors produced by different manufacturers and does
...