IEC TS 63126:2025

IEC TS 63126 ®
Edition 2.0 2025-10
TECHNICAL
SPECIFICATION
REDLINE VERSION
Guidelines for qualifying PV modules, components and materials for operation
at high temperatures
ICS 27.160 ISBN 978-2-8327-0787-6
IEC TS 63216:2025-10 RLV(en)
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CONTENTS
FOREWORD . 3
INTRODUCTION . 1
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 9
3.1 Terms and definitions. 9
3.2 Sheet-related definitions . 11
4 Modifications to IEC 61215-2 the IEC 61215 series . 12
4.1 General . 12
4.2 Hot-spot endurance test (MQT 09) . 12
4.3 UV preconditioning test (MQT 10) . 12
4.4 Thermal cycling test (MQT 11) . 12
4.5 Bypass diode testing (MQT 18) . 13
5 Modifications to the IEC 61730 series . 13
5.1 IEC 61730-1 . 13
5.2 IEC 61730-2 . 14
5.2.1 General . 14
5.2.2 Hot-spot endurance test (MST 22) . 14
5.2.3 Bypass diode thermal test (MST 25) . 14
5.2.4 Materials creep test (MST 37) . 14
5.2.5 Thermal cycling test (MST 51) . 14
5.2.6 UV test (MST 54) . 14
5.2.7 Dry heat conditioning (MST 56) . 14
6 Modifications to component standards . 14
6.1 Polymeric packaging material testing requirements . 14
6.1.1 Test procedures for optical durability of polymer packaging materials . 14
6.1.2 Polymeric backsheets and frontsheets . 14
6.2 Junction boxes according to IEC 62790 . 16
6.3 Connectors for DC application in photovoltaic systems according to
IEC 62852 . 16
6.4 Electric cables for photovoltaic systems with a voltage rating of 1,5 kV DC
according to IEC 62930 . 17
7 Test modification summary . 18
8 Reporting . 20
Annex A (informative) Determination of temperature level . 21
A.1 General . 21
A.2 Modelling . 21
th
A.3 98 percentile temperatures (T T ) . 25
98th 98
A.4 Guidance on module temperature for locations worldwide . 28
A.5 Guidance to system design specific modifications . 31
A.6 Site specific concerns . 32
A.7 Guidance on module temperature for several locations . 26
Bibliography . 36

Figure A.1 – Open-rack or rack-mounted configuration (open) . 23
Figure A.2 – Close-roof configuration . 23
Figure A.3 – Insulated-backsheet configuration . 24
Figure A.4 – Variety of standoff distances [3] . 24
Figure A.5 – Exponential decay fit to data from Fuentes [11], Formula (A.2) . 25
Figure A.6 – Histogram and cumulative distribution function (CDF) of module
temperature for Riyadh, Saudi Arabia . 27
Figure A.7 – Time series from the temperature model for Riyadh, Saudi Arabia . 28
th
Figure A.8 – Minimum standoff distance for a module estimated to achieve a 98
percentile temperature of 70 °C and to qualify for Level 0 . 30
th
Figure A.9 – Minimum standoff distance for a module estimated to achieve a 98
percentile temperature of 80 °C and to qualify for Level 1 or Level 0 . 30
th
Figure A.10 – 98 percentile temperature for an open-rack, or thermally unrestricted,
glass superstrate, polymer backsheet module . 33
th
Figure A.11 – 98 percentile temperature for a close-roof mounted glass superstrate,
polymer glass backsheet module . 34
th
Figure A.12 – 98 percentile temperature for insulated-back glass superstrate,
polymer backsheet module . 35

Table 1 – UV and thermal exposure conditions for backsheets and frontsheets. 16
Table 2 – Test modification summary . 18
Table 3 – Parameters for module temperature model according to Formula (A.1) . 22

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Guidelines for qualifying PV modules, components
and materials for operation at high temperatures

FOREWORD
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shall not be held responsible for identifying any or all such patent rights.
This redline version of the official IEC Standard allows the user to identify the changes made
to the previous edition IEC TS 63126:2020. A vertical bar appears in the margin wherever a
change has been made. Additions are in green text, deletions are in strikethrough red text.

IEC TS 63126 has been prepared by IEC technical committee 82: Solar photovoltaic energy
systems. It is a Technical Specification.
This second edition cancels and replaces the first edition published in 2020. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition.
a) Updated the Introduction and Scope to clarify the appl
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