IEC TS 63202-4:2022

IEC TS 63202-4 ®
Edition 1.0 2022-06
TECHNICAL
SPECIFICATION
colour
inside
Photovoltaic cells –
Part 4: Measurement of light and elevated temperature induced degradation of
crystalline silicon photovoltaic cells
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Secretariat Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
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 IEC Products & Services Portal - products.iec.ch
The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the
variety of criteria (reference number, text, technical publications previews. With a subscription you will always have
committee, …). It also gives information on projects, replaced access to up to date content tailored to your needs.
and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 300 terminological entries in English
details all new publications released. Available online and once
and French, with equivalent terms in 19 additional languages.
a month by email.
Also known as the International Electrotechnical Vocabulary

(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc

If you wish to give us your feedback on this publication or need
further assistance, please contact the Customer Service
Centre: sales@iec.ch.
IEC TS 63202-4 ®
Edition 1.0 2022-06
TECHNICAL
SPECIFICATION
colour
inside
Photovoltaic cells –
Part 4: Measurement of light and elevated temperature induced degradation of

crystalline silicon photovoltaic cells

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-3924-7

– 2 – IEC TS 63202-4:2022 © IEC 2022
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Apparatus . 6
5 Sampling . 6
6 Measurement . 7
7 Report . 8
Annex A (informative) LETID behaviour . 9
Bibliography . 10

Figure A.1 – Dependence of ΔP on cumulative irradiation dose . 9
max
Table A.1 – Summary of the LETID behaviours for the curves in Figure A.1 . 9

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTOVOLTAIC CELLS –
Part 4: Measurement of light and elevated temperature induced
degradation of crystalline silicon photovoltaic cells

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.
IEC TS 63202-4 has been prepared by IEC technical committee 82: Solar photovoltaic energy
systems. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
82/1994/DTS 82/2043/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.

– 4 – IEC TS 63202-4:2022 © IEC 2022
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at https://www.iec.ch/members_experts/refdocs. The main document types developed by IEC
are described in greater detail at https://www.iec.ch/standardsdev/publications.
A list of all parts in the IEC 63202 series, published under the general title Photovoltaic cells,
can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under 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.
IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it
contains colours which are considered to be useful for the correct understanding of its
contents. Users should therefore print this document using a colour printer.

PHOTOVOLTAIC CELLS –
Part 4: Measurement of light and elevated temperature induced
degradation of crystalline silicon photovoltaic cells

1 Scope
This part of IEC 63202 describes procedures for measuring the light and elevated temperature
induced degradation (LETID) of crystalline silicon photovoltaic (PV) cells in simulated sunlight.
The requirements for measuring initial light induced degradation (LID) of crystalline silicon PV
cells are covered by IEC 63202-1, where LID degradation risk of PV cells under moderate
-2
temperature and initial durations within termination criteria of 20 kWh·m are evaluated.
Energy yield of PV modules is significantly affected by the inherent LETID performance of the
PV cells, which are used in it. This LETID performance includes LID and other degradation
mechanisms. The procedures described in this document are to evaluate the degradation
behaviour of PV cells under elevated temperature and longer duration of light irradiation. The
degradation rate, maximum degradation ratio and possible regeneration are determined by
comparing the cell maximum power, Pmax, at Standard Test Conditions (STC) during the light
irradiation process with respect to the initial P . A P degradation profile with respect to
max max
cumulative irradiation is presented, which helps cell manufacturer to judge whether the cells
are prone to LETID before being assembled into modules.
Different from some other standards which separate boron-oxygen induced LID from LETID or
are limited to charge carrier injection induced degradation [1] , the overall degradation under
light irradiation at elevated temperature is included in the procedures described in this
document. The overall degradation, determined using this procedure, is more relevant to
various degradation mechanisms under field condition and gives a better evaluation of LETID
-2
risk. For cells with strong initial degradation within around 20 kWh·m , the procedures to
measure initial light induced degradation (LID) in IEC 63202-1 can be applied. Compared with
module LETID detection method described in IEC TS 63342, higher injection level under open-
circuit condition is used to shorten the test duration, while the temperature is identical.
The procedures described in this document can be used to detect the LETID risks of PV cells
[2],[3] and to judge the effectiveness of LETID mitigation measures, e.g. quick test for
production monitoring, thus helping improve the energy yield of PV modules.
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 60904-1, Photovoltaic devices – Part 1: Measurement of photovoltaic current-voltage
characteristics
IEC 60904-2, Photovoltaic devices – Part 2: Requirements for photovoltaic reference devices
___________
Numbers in square brackets refer to the Bibliography.

– 6 – IEC TS 63202-4:2022 © IEC 2022
IEC 60904-9, Photovoltaic devices – Part 9: Classification of solar simulator characteristics
IEC TS 61836, Solar photovoltaic energy systems – Terms, definitions and symbols
IEC 63202-1:2019, Photovoltaic cells – Part 1: Measurement of light-induced degradation of
crystalline silicon photovoltaic cells
IEC TS 63202-2:2021, Photovoltaic cells – Part 2: Electroluminescence imaging of crystalline
silicon solar cells
IEC TS 63342, Light and elevated temperature induced degradation (LETID) test for c-Si
Photovoltaic (PV) modules: Detection
3 Terms and definitions
For the purposes of this document, the terms and definitions in IEC TS 61836 and IEC 63202-1
apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
4 Apparatus
The following apparatus are required to perform the LETID test defined in this document.
a) A light soaking apparatus with temperature controller that meets following requirements:
1) one or more irradiance sensors (meeting the requirements of IEC 60904-2) to monitor
the cumulative irradiance;
2) the means to mount test cells co-planar with the irradiance sensors;
o
3) the capability to control cell temperature in the range of (75 ± 2) C during the light
-2
irradiation with an irradiance of (1 000 ± 50) W·m ;
4) relative humidity ≤ 50 %;
5) internal air shall
...