IEC 62788-1-7:2020

Measurement procedures for materials used in photovoltaic modules - Part 1-7: Encapsulants - Test procedure of optical durability

IEC 62788-1-7:2020 is designed as a more rigorous qualification test, using accelerated UV exposure at elevated temperature to determine whether polymeric encapsulants can suffer loss of optical transmittance. IEC 61215-2 already includes a UV preconditioning test (MQT 10), however, the parameters for that test only represent a limited level of exposure (~weeks of UV dose). This test procedure is intended for representative coupon specimens, applying stress at a greater intensity (designed relative to Phoenix, AZ), using a radiation spectrum that is more similar to the terrestrial solar spectrum, and using a duration of exposure that is more relevant to the PV application (i.e., equivalent to several years of outdoor exposure). This test quantifies the degradation rate of encapsulants so that the risk of the materials losing optical transmittance during operation in the terrestrial environments can be managed. The quantitative correlation between climate (or location of use), a specific application (utility installation, residential-installation, roof-mount, rack-mount, use of a tracker, the system electrical configuration and its operation), and the test can be established for each specific encapsulant material, but is beyond the scope of this document.

Procédures de mesure des matériaux utilisés dans les modules photovoltaïques - Part 1-7: Encapsulants - Procédure d’essai de la durabilité optique

l’IEC 62788-1-7:2020 est conçue comme un essai de qualification plus rigoureux, qui utilise une exposition aux UV accélérée à température élevée destinée à déterminer si les encapsulants polymérisés peuvent présenter une perte de facteur de transmission optique. L’IEC 61215-2 comprend déjà un essai de préconditionnement aux UV (MQT 10), toutefois, les paramètres de cet essai ne représentent qu’un niveau limité d’exposition (~semaines de dose d’UV). La présente procédure d'essai concerne les éprouvettes de coupon représentatives et applique des contraintes d’une plus grande intensité (conçues par rapport à Phoenix, AZ), en utilisant un spectre de rayonnement qui est plus proche du spectre lumineux solaire terrestre et une durée d'exposition plus pertinente pour l’application PV (c’est à dire équivalente à plusieurs années d'exposition en extérieur). Cet essai quantifie la vitesse de dégradation des encapsulants de manière à pouvoir gérer le risque de perte de facteur de transmission optique des matériaux au cours du fonctionnement dans l’environnement terrestre. La corrélation quantitative entre le climat (ou le lieu d'utilisation), une application spécifique (installation de service public, installation résidentielle, montage sur toit, montage sur châssis, utilisation d'un traqueur, configuration électrique du système et son fonctionnement) et l’essai peut être établie pour chaque matériau d’encapsulation spécifique mais n’entre pas dans le domaine d’application du présent document.

General Information

• Status: Published
• Publication Date: 20-Apr-2020
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 27.160 - Solar energy engineering
• Technical Committee: TC 82 - Solar photovoltaic energy systems
• Drafting Committee: WG 2 - TC 82/WG 2
• Current Stage: PPUB - Publication issued
• Start Date: 17-Apr-2020
• Completion Date: 21-Apr-2020

Standards Content (Sample)

IEC 62788-1-7 ®
Edition 1.0 2020-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measurement procedures for materials used in photovoltaic modules –
Part 1-7: Encapsulants – Test procedure of optical durability

Procédures de mesure des matériaux utilisés dans les modules
photovoltaïques –
Partie 1-7: Encapsulants – Procédure d’essai de la durabilité optique

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IEC 62788-1-7 ®
Edition 1.0 2020-04
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Measurement procedures for materials used in photovoltaic modules –

Part 1-7: Encapsulants – Test procedure of optical durability

Procédures de mesure des matériaux utilisés dans les modules

photovoltaïques –
Partie 1-7: Encapsulants – Procédure d’essai de la durabilité optique

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.160 ISBN 978-2-8322-8035-5

– 2 – IEC 62788-1-7:2020 © IEC 2020
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Principle . 7
5 Apparatus . 7
5.1 Spectrophotometer for transmittance measurements . 7
5.2 Environmental chamber for weathering . 7
6 Test specimens . 8
6.1 Specimen components and general considerations for all material types . 8
6.2 Test specimens for datasheet reporting . 8
6.3 Use of alternate superstrate and substrate materials . 8
6.4 Witness specimens and experimental control . 9
7 Measurement procedure . 9
8 Artificial accelerated weathering . 9
9 Calculation and expression of results . 9
10 Test procedure . 10
11 Pass/fail criteria . 10
12 Test report . 11
Bibliography . 13

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEASUREMENT PROCEDURES FOR
MATERIALS USED IN PHOTOVOLTAIC MODULES –

Part 1-7: Encapsulants –
Test procedure of optical durability

FOREWORD
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International Standard IEC 62788-1-7 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
82/1669/FDIS 82/1704/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.
A list of all parts in the IEC 62788 series, published under the general title Measurement
procedures for materials used in photovoltaic modules, can be found on the IEC website.

– 4 – IEC 62788-1-7:2020 © 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.
INTRODUCTION
IEC 61215-2 (covering module design qualification and type approval) specifies a UV
-2 -2
preconditioning of 54 MJ⋅m (15 kWh⋅m ), which would be encountered after ~40 ideal sunny
days of exposure to the AM1.5G UV spectrum in IEC 60904-3. IEC 61730-2 presently specifies
4x the same UV exposure, i.e., 5 months UV dose. The International PV Quality Assurance
Task Force (PVQAT) leads global efforts to craft quality and reliability standards for solar
energy technologies. These standards will allow stakeholders to quickly assess a solar
photovoltaic (PV) module's performance and ability to withstand weather stresses, thereby
reducing risk and adding confidence for those developing products, designing incentive
programs, and determining private investments. As developed in conjunction with PVQAT, this
part of IEC 62788-1 is intended to supplement module qualification, which typically covers
reliability issues related to infant mortality, i.e., the first months of field use. This part of
IEC 62788-1 may also facilitate the pre-qualification of encapsulation materials using coupon
specimens, because long term weathering is not practical for larger module specimens. This
part of IEC 62788-1 also importantly uses high fidelity UV irradiation (relati
...