NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

International PV QA Task Force 

(PVQAT)

Sarah Kurtz – representing many people

SOPHIA Workshop

Freiburg, Germany

June 3 – 4, 2014

NREL/PR-5J00-62136
2

Outline: Three-prong effort plus next steps

1. Qualification of durability of design of products for 

chosen climate and mounting

2. Guide for audit of 

 consistent manufacturing

 of products built to that 

 design

3. Certification process for 

 system verification to 

 ensure adequacy of design, 

 installation, and operation

Next goal: Service Life Prediction

Bankable PV

Consistent 

manufacturing

System 

verification

Standards

Durable 

design
3

Levels of Accelerated Testing

IEC Qualification Comparative Service Life

Purpose Minimum design 

qualification

Comparison of 

products

Reduction of cost 

while still meeting 

warranty

Quantification Pass/fail Relative Absolute

Climate or 

application

(mounting)

Not differentiated Differentiated Differentiated

Specificity Silicon, thin-film, 

CPV Package specific? Product specific

Chamber test times Modules: < 2 

months 6 months 3 years ?
4

Why Differentiate Durability?

• The reliability engineer prefers a single 

design

• The marketing department desires a product 

for every customer

• Differentiation is valuable:

o When it enables a lower cost design for a specific 

use environment

o When it quantifies the added value of higher 

durability (and quality)
5

1. Durable Design Proposal for Climate-specific rating

PVQAT is developing technical basis for:

IEC 60721-2-1 Climate 

Designation Mounting classes

Rack mount Close-roof mount

Moderate (Temperate) ✔ ✔

Warm Damp, Equable 

(Tropical) ✔ ✔

Extremely Warm Dry 

(Desert) ✔ ✔
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1. Durable Design – Climate-specific rating

Strawman proposal: details to be debated

IEC 60721-2-1 Climate 

Designation Mounting classes

Rack mount Close-roof mount

Moderate (Temperate)

Leg 1: 500 thermal cycles 

Leg 2: Increased UV exposure at 

60 °C followed by 10 cycles of 

HF and 500 hours of Damp Heat 

(85/85)

Leg 1: 500 thermal cycles 

Leg 2: Increased UV exposure at 

80 °C followed by 10 cycles of 

HF and 500 hours of Damp Heat 

(85/85)

Warm Damp, Equable 

(Tropical)

Leg 1: 500 thermal cycles 

Leg 2: Increased UV exposure at 

80 °C followed by 10 cycles of 

HF and 1000 hours of Damp Heat 

(85/85)

Leg 1: 500 thermal cycles 

Leg 2: Increased UV exposure at 

80 °C followed by 10 cycles of 

HF and 1000 hours of Damp Heat 

(85/85)

Extremely Warm Dry 

(Desert)

Leg 1: 500 thermal cycles 

Leg 2: Increased UV exposure at 

80 °C followed by 10 cycles of 

HF and 1000 hours of Damp Heat 

(85/40)

Leg 1: 500 thermal cycles 

Leg 2: Increased UV exposure at 

100 °C followed by 10 cycles of 

HF and 1000 hours of Damp Heat 

(85/40)
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Two Test Sequences - #1

Leg 1 – Thermal cycling

Most reports show #1 

cause of failures to be 

solder bonds and similar

What is the right 

number?
8

Two Test Sequences - #2

Leg 2 – Delamination and corrosion

Corrosion and 

delamination are observed 

to depend on climate

What are the right 

conditions?
9

Two Test Sequences – plus material tests

Materials tests 

may reduce 

expense
10

1. Durable Design – Climate-specific rating

IEC 60721-2-1 Climate 

Designation Mounting classes

Rack mount Close-roof mount

Moderate (Temperate) ✔ ✔

Warm Damp, Equable 

(Tropical) ✔ ✔

Extremely Warm Dry 

(Desert) ✔ ✔

Rating system considers three climates, two mounting classes, 

and additional stresses such as snow, wind, hail, salt, sand

Status: accepted as a proposal by IEC – many details still to be 

completed: we need your inputs!
11

2. Consistent Manufacturing – PV QMS

• Guide for PV Quality 

Management System 

http://www.nrel.gov/docs/fy13os

ti/58940.pdf

• Builds on Japanese standard*

• Status: Revised IEC draft to be 

discussed in Korea

• Goal: IEC Technical 

Specification in 2015

• Future vision: More detailed 

version to differentiate QMS

*JIS Q8901-2012 Terrestrial photovoltaic (PV) 

modules-Requirement for reliability assurance 

system (design, production, and product 

warranty) 

Technical work led by PVQAT
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3. System Verification – IECRE

®

IEC has formed IECRE for Renewable Energy 

System verification

- Component quality

- System 

- Design

- Installation

- Operation

- Training of personnel

IECRE

PV Standards for testing all aspects of PV 

Systems:

PVQAT has formed Task Group 11 to provide input into 

IECRE, especially as IECRE is getting started

WG3 will be discussing a cluster of documents in Korea
13

Service Life Prediction Standard?

• How would you write a standard for making a 

Service Life Prediction?

• The failure mechanisms that limit the life of a 

product may vary

• Current research is providing scientific basis, 

but we don’t have a draft standard yet
Steps to a Service Life Prediction:

1. Identify failure/degradation mechanisms that 

determine end of life

2. Quantify kinetic rates

3. For given use environment, apply kinetic rates 

within model to estimate expected lifetime

4. Verify model by comparing with field data

This step-by-step procedure is clear, 

but the actual tests are not

This procedure is similar to quality management
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Implement Service Life Prediction: QMS

• The best quality management 

systems assess whether the 

product can meet the warranty –

this is the best place to quantify 

Service Life

• A complete Service Life 

Prediction takes many years to 

create and verify – most aspects 

of the product design must be 

“frozen” first

• Propose (for example) to 

differentiate with ratings:

• New product

• Practiced

• Mature
16

Summary of PVQAT Efforts 

• Comparative Rating System:

o Three climates, two mounting classes; additional 

individual stresses

• Guide for Quality Management Systems

o Next steps could be more detailed

• Support IECRE: 

o System verification
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Summary of Questions 

• Comparative Rating System:

o Do we agree on the two legs?

o Which numbers are controversial?

• Guide for Quality Management Systems (QMS):

o Are we agreed to move to more detailed version that 

enables differentiation?

• IECRE: 

o What should be included?

o Do we want to define different requirements for utility, 

commercial and residential type systems?

• Service Life Prediction: 

o Should it be part of QMS, alongside of warranty 

documentation?
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Thank you to the PVQAT Task Leaders

• Task Group 1: PV QA guideline for manufacturing consistency — leaders Ivan Sinicco, Yoshihito 

Eguchi, Govind Ramu, Gunnar Brueggemann, Zhou Wei

• Task Group 2: PV QA testing for thermal and mechanical fatigue including vibration — leaders 

Nick Bosco, Tadanori Tanahashi

• Task Group 3: PV QA testing for humidity, temperature, and voltage — leaders John Wohlgemuth, 

Takuya Doi, Neelkanth Dhere

• Task Group 4: PV QA testing for diodes, shading and reverse bias — leaders Vivek Gade, Yasunori

Uchida, Paul Robusto

• Task Group 5: PV QA testing for UV, temperature, and humidity — leaders Michael Koehl, Tsuyoshi Shioda, Jasbir Bath, David Miller

• Task Group 6: Communication of PV QA ratings to the community — leaders David Williams and 

Sarah Kurtz

• Task Group 7: PV QA testing for snow and wind loading — previously, Joerg Althaus

• Task Group 8: PV QA testing for thin-film PV — leaders Neelkanth Dhere, Masayoshi Takani, Veronica Bermudez

• Task Group 9: PV QA testing for Concentrator PV (CPV) — leaders Nick Bosco, Itai Suez

• Task Group 10: Connectors — leader Juris Kalejs

• Task Group 11: QA for PV Systems — leader Sumanth Lokanath.

• George Kelly, and many others