Guidelines for qualifying PV modules, components and materials for operation at high temperatures

IEC TS 63126:2020 defines additional testing requirements for modules deployed under conditions leading to higher module temperature which are beyond the scope of IEC 61215-1 and IEC 61730-1 and the relevant component standards, IEC 62790 and IEC 62852. The testing conditions specified in IEC 61215-2 and IEC 61730-2 (and the relevant component standards IEC 62790 and IEC 62852) assumed that these standards are applicable for module deployment where the 98th percentile temperature (T98th), that is the temperature that a module would be expected to equal or exceed for 175,2 h per year, is less than 70 °C.
This document defines two temperature regimes, temperature level 1 and temperature level 2, which were designed considering deployment in environments with mounting configurations such that the T98th is less than or equal to 80 °C for temperature level 1, and less than or equal to 90 °C for temperature level 2.

General Information

Status
Published
Publication Date
21-Jun-2020
Current Stage
PPUB - Publication issued
Completion Date
22-Jun-2020
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IEC TS 63126
Edition 1.0 2020-06
TECHNICAL
SPECIFICATION
colour
inside
Guidelines for qualifying PV modules, components and materials for operation
at high temperatures
IEC TS 63126:2020-06(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TS 63126
Edition 1.0 2020-06
TECHNICAL
SPECIFICATION
colour
inside
Guidelines for qualifying PV modules, components and materials for operation
at high temperatures
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.160 ISBN 978-2-8322-8396-7

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TS 63126:2020 © IEC 2020
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms and definitions ...................................................................................................... 8

4 Modifications to IEC 61215-2 ........................................................................................... 9

4.1 General ................................................................................................................... 9

4.2 Hot-spot endurance test (MQT 09) .......................................................................... 9

4.3 UV preconditioning test (MQT 10) ........................................................................... 9

4.4 Thermal cycling test (MQT 11) ................................................................................ 9

4.5 Bypass diode testing (MQT 18) ............................................................................... 9

5 Modifications to IEC 61730 ............................................................................................ 10

5.1 IEC 61730-1 ......................................................................................................... 10

5.2 IEC 61730-2 ......................................................................................................... 10

5.2.1 General ......................................................................................................... 10

5.2.2 Hot spot endurance test (MST 22) ................................................................. 10

5.2.3 Bypass diode thermal test (MST 25) .............................................................. 10

5.2.4 Materials creep test (MST 37) ........................................................................ 10

5.2.5 Thermal cycling test (MST 51) ....................................................................... 11

5.2.6 UV test (MST 54) ........................................................................................... 11

5.2.7 Dry heat conditioning (MST 56) ..................................................................... 11

6 Modifications to component standards ........................................................................... 11

6.1 Polymeric packaging material testing requirements ............................................... 11

6.1.1 Test procedures for durability of polymer packaging materials ....................... 11

6.1.2 Polymeric back sheets and front sheets ......................................................... 11

6.2 Junction boxes according to IEC 62790 ................................................................ 11

6.3 Connectors for DC application in photovoltaic systems according to

IEC 62852 ............................................................................................................. 12

6.4 Electric cables for photovoltaic systems with a voltage rating of 1,5 KV DC

according to IEC 62930 ......................................................................................... 12

7 Test modification summary ............................................................................................ 12

8 Reporting....................................................................................................................... 12

Annex A (informative) Determination of temperature level .................................................... 13

A.1 General ................................................................................................................. 13

A.2 Modelling .............................................................................................................. 13

A.3 98 -percentile temperatures (T ) ..................................................................... 14

98th

A.4 Guidance on module temperature for several locations ......................................... 15

Bibliography .......................................................................................................................... 18

Figure A.1 – Histogram and CDF of module temperature for Riyadh, Saudi Arabia................ 15

Figure A.2 – Time series from the model for Riyadh .............................................................. 15

Figure A.3 – 98 -percentile temperature for an open-rack, or thermally unrestricted,

glass superstrate, polymer backsheet module ....................................................................... 16

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IEC TS 63126:2020 © IEC 2020 – 3 –

Figure A.4 – 98 -percentile temperature for a close-roof mounted glass superstrate,

polymer backsheet module ................................................................................................... 16

Figure A.5 – 98 -percentile temperature for insulated-back glass superstrate, polymer

backsheet module ................................................................................................................. 17

Table 1 – Test modification summary .................................................................................... 12

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– 4 – IEC TS 63126:2020 © IEC 2020
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GUIDELINES FOR QUALIFYING PV MODULES, COMPONENTS
AND MATERIALS FOR OPERATION AT HIGH TEMPERATURES
FOREWORD

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IEC TS 63126, which is a Technical Specification, has been prepared by IEC technical

committee 82: Solar photovoltaic energy systems.
---------------------- Page: 6 ----------------------
IEC TS 63126:2020 © IEC 2020 – 5 –
The text of this Technical Specification is based on the following documents:
Draft TS Report on voting
82/1662/DTS 82/1706A/RVDTS

Full information on the voting for the approval of this Technical Specification can be found in

the report on voting indicated in the above table.

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---------------------- Page: 7 ----------------------
– 6 – IEC TS 63126:2020 © IEC 2020
INTRODUCTION

The IEC 61215 series, IEC 61730 series, IEC 62790 and IEC 62852 are considered suitable for

an environmental temperature range of at least -40 °C to + 40 °C and for modules operating in

such conditions that a 98 percentile module operational temperature of 70 °C or less applies.

This environmental temperature range encompasses many locations and installation styles in

these locations. As an example, it has been determined that thermally unrestricted, or open-

rack-style structures, in most cases do not result in 98 percentile module operational

temperatures exceeding 70 °C and as such, the originating standards are suitable as written.

percentile
Module operating temperatures exceeding 70 °C, on the other hand, at the 98

typically will occur with roof-parallel or building-integrated roof top applications in climates with

local environmental temperatures that exceed 40 °C.

This document is written for two purposes: to provide modified testing conditions for modules

that will be deployed in climates that have a higher environmental air temperature than 40 °C

and/or for module installation methods that restrict cooling, resulting in higher operational

temperatures than anticipated in the originating standards. This work will also aid in providing

an alternative definition of “rack mount” in the context of IEC 61215 series and IEC 61730

series. This term was initially used as a place holder to restrict the scope of PV module type

testing for those installation styles that permit open and unrestricted cooling from all surfaces

of a PV module. Now that the testing has matured there is a desire to refine definitions for the

range of applicability of these standards.

This document is intended to be used as an intermediate step to define high temperature

environment use requirements. These requirements are planned to be incorporated into

standards in the future. It is not necessarily cost effective for module materials to comply with

level 1 or level 2 requirements defined in this document, unless the module temperature is

expected to exceed 70 °C at the 98 percentile. Module materials capable of temperature level

1 or temperature level 2 are expected to impose higher expectations of endurance and cost

than normal modules.

Component standard IEC 62930 is considered to be adequate for modules operating at high

temperatures without modification due to requiring cable to have a 120 °C or greater thermal

endurance at a 20 000 h correlation lifetime. Similarly, IEC 62979 is considered adequate for

bypass diode thermal runaway determination due to testing temperatures of 90 °C for roof-

mounted modules and 75°C for “rack mounted” modules.

Similar to electric cables, IEC 61730-1 requires a RTI, TI, or RTE of 90 °C or larger. A module

operating in an environment and installation style resulting in a 98 percentile temperature of

70 °C requires a RTI, TI, or RTE safety factor of +20 °C to establish a 25-year lifetime when

the polymer has a minimum activation energy of 46 kJ/mol and the correlation lifetime is

20 000 h. This work applies that safety factor of +20 °C for polymer RTI, TI, or RTE when the

98 percentile operating temperature is above 70 °C.

Finally, data from PV modules in hot climates and modelling were used to understand operating

temperatures and resulted in two categories of high temperature operation, temperature level 1

and temperature level 2. These categories are defined within this document and it is relevant

to indicate that level 2 temperatures were not found in field data, but may result from insulated

substrate modules on pitched roofs facing the sun when ambient air temperature exceeds

40 °C. This may be most consistent with building-integrated PV module roofs and to allow for

this possibility, the temperature level 2 category remains in this document.
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IEC TS 63126:2020 © IEC 2020 – 7 –
GUIDELINES FOR QUALIFYING PV MODULES, COMPONENTS
AND MATERIALS FOR OPERATION AT HIGH TEMPERATURES
1 Scope

This document defines additional testing requirements for modules deployed under conditions

leading to higher module temperature which are beyond the scope of IEC 61215-1 and

IEC 61730-1 and the relevant component standards, IEC 62790 and IEC 62852. The testing

conditions specified in IEC 61215-2 and IEC 61730-2 (and the relevant component standards

IEC 62790 and IEC 62852) assumed that these standards are applicable for module

deployment where the 98 percentile temperature (T ), that is the temperature that a module

98th
would be expected to equal or exceed for 175,2 h per year, is less than 70 °C.

NOTE 175,2 h represents 2 % of a total year as some thermal failure modes are a function of time at temperature

and not sensitive to day-only or night-only exposure.

This document defines two temperature regimes, temperature level 1 and temperature level 2,

which were designed considering deployment in environments with mounting configurations

such that the T is less than or equal to 80 °C for temperature level 1, and less than or equal

98th

to 90 °C for temperature level 2. This document provides recommended additional testing

conditions within the IEC 61215 series, IEC 61730 series, IEC 62790 and IEC 62852 for module

operation in temperature levels 1 and 2.
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 61215-2:2016, 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 TS 61836, Solar photovoltaic energy systems – Terms, definitions and symbols

IEC 62788-1-7, Measurement procedures for materials used in photovoltaic modules – Part 1-

7: Encapsulants – Test procedure of optical durability

IEC TS 62788-2:2017, Measurement procedures for materials used in photovoltaic modules –

Part 2: Polymeric materials – Frontsheets and backsheets

IEC TS 62788-7-2, Measurement procedures for materials used in photovoltaic modules –

Part 7-2: Environmental exposures – Accelerated weathering tests of polymeric materials

IEC 62790, Junction boxes for photovoltaic modules – Safety requirements and tests

---------------------- Page: 9 ----------------------
– 8 – IEC TS 63126:2020 © IEC 2020

IEC 62852, Connectors for DC-application in photovoltaic systems – Safety requirements and

tests
IEC 62930, Electric cables for photovoltaic s
...

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