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IEC Quality Assurance Task Group 5: 

UV, Temperature, and Humidity

NREL PV Module Reliability Workshop

David C. Miller* (*speaker, NREL, USA, David.Miller@nrel.gov), 

Jasbir Bath (SEMA, USA, jasbir_bath@yahoo.com),

Michael Köhl (Fraunhofer ISE, Germany, michael.koehl@ise.fraunhofer.de),

Tsuyoshi Shioda (Mitsui Chemical Co., Japan, Tsuyoshi.Shioda@mitsui-chem.co.jp)

Index #99, Wednesday, February 26, 4:40-4:50 pm

Golden, Colorado

-this presentation contains no proprietary informationNREL/PR-5200-61493
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Topics Covered Today

• Motivation: Goals and activities for QA TG5

• Ea interlaboratory experiment (TG5 US)

Motivation

Some details of the Ea experiment

• Timeline for TG5

• Mini-module experiment (TG5 Japan)

• SoPhia round-robin (TG5 Europe)
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Goal and Activities for QA TG5 (UV, T, RH)

• IEC qualification tests (61215, 61646, 61730-2) presently prescribe up to 137 days field 

equivalent (IEC 60904-3 AM 1.5) UV-B dose

• Goal: develop UV- and temperature-facilitated test protocol(s) that may be used to 

compare PV materials, components, and modules relative to a field deployment.

Core Activities:

1: Study weathering and climates (location-dependent information).

e.g., known benchmark locations...Miami, FL; Phoenix, AZ

2: Leverage existing standards, including other industries.

√ summary exists from Kurt Scott et al.

3: Improve understanding of existing PV UV tests. 

4: Improve understanding of module durability.

 4-1 Collect information about observed failure modes.

e.g., the literature, site inspections

 4-2 Confirm appropriate models for aging.

5: Verify suitable UV sources. 

√ summary of module capable equipment from David Burns et al.

6: Generate protocol for accelerated service testing.

7: Perform laboratory verification of proposed test standard/failure mode.

mini-module study, SoPhia round-robin, Ea interlaboratory study 
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Motivation for the Ea Interlaboratory Experiment (TG5 US)

• Knowing Ea (for rate of change in a characteristic) is critical to prescribing and 

interpreting a UV- and temperature-mediated test.

• Unfortunately, Ea is not known for the common UV-related PV degradation modes.

Critical unknowns

(Goals for the interlaboratory experiment):

1. Quantify Ea so that applied test conditions can be interpreted.

2. Provide a sense of the range of Ea that may be present by examining “known bad,” 

“known good,” and “intermediate” material formulations.

3. Determine if there is significant coupling between relevant aging factors, 

i.e., UV, temperature, and humidity.

What factors does TG5 need to consider?

4. Investigate the spectral requirements for light sources by comparing Ea for different 

sources, i.e., Xe-arc, UVA 340.

Is visible light required in addition to UV light?

The modified Arrhenius equation





 



 −





 





=

RT

n Ea

e

T

T k A

0
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Some Details of the Ea Methods and Experiment

Optical transmittance:

• (5) EVA + (1) TPU in 

encapsulation 

transmittance study. 

• (10) intermittent 

measurements will 

be performed. 

Transmittance will be examined 

using silica/polymer/silica samples.

A DCB wedge test will be used to 

examine the attachment of edge seals.

Marceau et. al., Adhesives Age, 1977, 28-34.

The CST will be used to examine 

the attachment of EVA.

Overlap shear will be used to examine 

the attachment of edge seals.

Photo courtesy Kempe et al.

Mechanical attachment:

• (1) EVA will be 

examined using the 

compressive shear test.

• (2) edge seals will be 

examined using shear 

and wedge tests.

• (5) intermittent 

measurements will be 

performed. 
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The Ea Interlaboratory Experiment Enables a Wider Range of Study

• Discoloration and adhesion will be studied in detail at different institutions using 

the same make and model of instrument (i.e., Ci5000, QUV).

• This overcomes the difficulty of limitedly available aging equipment.

• A standard condition (60°C in chamber) allows a broad variety of other instruments 

(light sources) to also be compared.

• Rate of degradation will be compared against field data to allow site-specific 

acceleration factors to be determined.

• Outdoor data will verify validity of the test.

• Separate experiment at NIST (same EVA’s) will determine action spectrum.

Summary of participating laboratories and test conditions
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Timeline and Goals for TG5
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The Mini-Module and SoPhia R-R TG5 Experiments

Mini-Module Experiment (TG5 Japan)

• Examines module performance (I/V), encapsulation durability, 

and backsheet durability after aging (UV, T, %RH).

• UV exposure can affect results of other tests, i.e., DH and TC.

• Will be examining adhesion within PV modules.

• See also PVMRW 2014 poster (index #85) by Shioda et al.

SoPhia R-R (TG5 Europe)

• Samples (7) backsheet vendors at (7) test labs. 

• Examines light sources (fluorescent, metal-halide, xenon) 

using 3 long-pass and 2 neutral-density filters.

• Examining test temperature (60°C and 80°C used in experiment).

• Refer to future work of Köhl et al.
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Acknowledgements

• There has been fantastic participation in TG5. 

Thank you - to the many participants! 

• If interested in TG5 or the experiments, please contact the 

corresponding regional TG5 leader. (See title slide)

• Let me know if you are interested in any of the related material 

standards? (encapsulation transmittance, encapsulation 

adhesion, edge-seal attachment)

• TG5 dinner meeting 

Wednesday, 2/26, 6:15 pm at

 Mimi’s Café (14265 W Colfax Ave)

NREL STM campus, Dennis Schroeder

This work was supported by the U.S. 

Department of Energy under Contract 

No. DE-AC36-08-GO28308 with the 

National Renewable Energy Laboratory.