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Linkage to Previous International PV QA Task Force Workshops; Proposal for Rating System

NREL PV ModWorkshopFeb. 26, 2013Sarah Kurtz, NJohn WohlgemTony Sample, Masaaki YamaMichio KondoNREL/PR-5200-58373
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Outline

• History of International PV Module Q

Force

• How do we do something useful with

doing something harmful?

• Opportunity for Rating System to pro

value over current qualification tests

• Technical basis for Rating System• Next steps for creating Rating Syste

2
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Motivation: the question on the s

“How do I predict lifetime of PV mo

• Reliability engineer: How do I test to 

determine the number of years for thwarranty?

• PV customer: How do I choose the P

module that will last longer?

• PV investor: How do I know that I’m 

a safe investment of $1 billion (if the fail after 10 yr, the warranty may be worthless if the company is gone)?

• Insurance company: How do I deter

rates for insuring PV installations?

3
International PV Module Qu

Assurance Forum 

San Francisco, July, 2011 Goals: 

1. Create a QA Rating System to differentiate the relat

module designs1) Compare module designs2) Provide a basis for manufacturers’ warranties 3) Provide investors with confidence in their investm4) Provide data for setting insurance rates

2. Create a guideline for factory inspections of the QA 

during manufacturing.

Hosted by

NREL

AIST

PVTEC

SupporteMETIJRCUS DOESEMI PV 

A little history
The PV QA Task Force was formed at the conclusion of the F

consisted of five Task Groups:Task Group 1: PV QA Guideline for Manufacturing Consiste

(leaders Ivan Sinicco, Alex Mikonowicz, YoshWei Zhou, G. Breggemann)

Task Group 2: PV QA Testing for Thermal and mechanical fa

vibration (leader Chris Flueckiger, Tadanori T

Task Group 3: PV QA Testing for Humidity, temperature, and 

(leaders John Wohlgemuth, Neelkanth Dhere, 

Task Group 4: PV QA Testing for Diodes, shading and rever

(leaders Vivek Gade, Paul Robusto, Yasunori 

Task Group 5: PV QA Testing for UV, temperature and humi

(leader Michael Köhl, Kusato Hirota, Jasbir Ba

A little history

These groups began meeting by teleconference in summer oSince then, four other task groups have been added.
The PV QA Task Force was formed at the conclusion of the F

consisted of five Task Groups:Task Group 1: PV QA Guideline for Manufacturing Consiste

International meeting in parallel with mduring next two days

Task Group 2: PV QA Testing for Thermal and mechanical fa

vibration (leader Chris Flueckiger, Tadanori Ta

Task Group 3: PV QA Testing for Humidity, temperature, and 

(leaders John Wohlgemuth, Neelkanth Dhere, 

Task Group 4: PV QA Testing for Diodes, shading and rever

(leaders Vivek Gade, Paul Robusto, Yasunori 

Task Group 5: PV QA Testing for UV, temperature and humi

(leader Michael Köhl, Kusato Hirota, Jasbir Ba

These groups began meeting by teleconference in summer oSince then, four other task groups have been added.
The PV QA Task Force was formed at the conclusion of the F

consisted of five Task Groups:Task Group 1: PV QA Guideline for Manufacturing Consiste

(leaders Ivan Sinicco, Alex Mikonowicz, YoshWei Zhou, G. Breggemann)

Task Group 2: PV QA Testing for Thermal and mechanical fa

vibration (leader Chris Flueckiger, Tadanori)

Task Group 3: PV QA Testing for Humidity, temperature, and 

(leaders John Wohlgemuth, Neelkanth Dhere

Task Group 4: PV QA Testing for Diodes, shading and rever

(leaders Vivek Gade, Paul Robusto, Yasunori 

Task Group 5: PV QA Testing for UV, temperature and humi

(leader Michael Köhl, Kusato Hirota, Jasbir Ba

A little history

These groups began meeting by teleconference in summer oSince then, four other task groups have been added.

These four groups are meeting today and tomface-to-face regional meeting, with some inteparticipationGoal: Share technical studies that will guide most useful tests. Where appropriate: propostructure
Additional Task Groups:

Task Group 6: Communication of PV QA Ratings to the 

(leaders David Williams, Sarah Kurtz)

Rest of this talk

Task Group 7: PV QA Testing for Wind and Snow Loads

(leader Joerg Althaus)

Task Group 8: Thin Film Testing

(leaders: Neelkanth Dhere, Veronica Bermudez, Tobias Rosche

Kick off Feb. 28 – March 1, Golden, CO

Task Group 9: CPV Testing

(leaders: Itai Suez, Nick Bosco)
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Need for Rating System

Task Groups develop accelerated tests to predict expe

How do we communicate the 

Rating System

Task Group 2: Testing for Thermal and mechanical fatigueTask Group 3: Testing for Humidity, temperature, and voltageTask Group 4: Testing for Diodes, shading and reverse bias

Task Group 5: Testing for UV, temperature and humidity

Task Group 7: Testing for Snow and Wind Loading
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• Must be predictive & relevant

• (correlate with decades of field experience, not 

• Must be communicated in useful ways 

• (both simple and detailed for different audiences

• Must be cost and time effective

• (manufacturers must bring the product to marke

• Must be beneficial to PV community

• (use wisdom of community to identify good choi

Principles for creating tests/ratin
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To Define the Rating System, Fir

When are failures slipping p

Qualification testing?

What are we missing?
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Prioritize two types of wear-out mechanisms threported:• Broken interconnections, solder bonds, diodes• Encapsulant discoloration and/or delaminationWe choose to focus first on these; later we’ll adlonger list of wear-out mechanisms.Rating System – What are we missincurrent qualification tests?
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1. In response to:• Broken interconnections, solder bonds, diodesAdd:- Additional thermal cycling or mechanical stre

bypass diode/shading testing

2. In response to:• Encapsulant discoloration and/or delaminationAdd:- Additional UV stressRating System – First address wear is slipping past the qualification test
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Need to apply additional stress to detect early wear 

Level Humidity High Temperature Thermal cycling and diode testing 

Qualificationtest No new No new No new Wear out comparative test

No new No new New 

To gain confidence in long-term performance in almost all clim

add tests related to thermal cycling, diodes, and UV e
NATIONAL RENEWABLE ENERGY LABORATORY

Need to apply additional stress to detect early wear 

Level Humidity High Temperature Thermal cycling and diode testing 

Qualificationtest No new No new No new Wear out comparative test

No new No new New 

To gain confidence in long-term performance in almost all clim

add tests related to thermal cycling, diodes, and UV e

What about for extreme climates?

Marine ✔(salt spray)

Snow loads ✔ (mechanical loads

Hail ✔ (hail impact)

Heat

Humidity

✔Note: We already have comparative tests for marine, hail, 

can include these test results in the rating 
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Additional stress may be needed for extreme climat

New Tests Will Require Additional Stress Target

Failure types, loosely grouped

Thermal 

cycling & 

diode

testing

UV High Temperature High humidity Proposed labels ★or “C” 

Infantmortality

-- - -

Qualification 

test

- 

Interconnects, discoloration, delamination

✔ ✔ - - Hot-cold Better tha

qualification 

Heat-induced failures ✔✔ ✔ - Hot-dry Better tha

qualification 

Humidityinduced failures

- ✔ ✔ ✔ Hot-humid Better tha

qualification 

The two primary extremes that have not yet been address

Heat

Humidity

So add additional stress for these, indicated by ✔
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New Tests Will Require Additional Stress Target

Failure types, loosely grouped

Thermal 

cycling & 

diode

testing

UV High Temperature High humidity Proposed labels ★or “C” 

Infantmortality

-- - -

Qualification 

test

- 

Interconnects, discoloration, delamination

✔ ✔ - - Hot-cold Better tha

qualification 

Heat-induced failures ✔✔ ✔ - Hot-dry Better tha

qualification 

Humidityinduced failures

- ✔ ✔ ✔ Hot-humid Better tha

qualification 

Rating System – Targets for defining the min/max mea

With these ranges, we can address the full range from today’s 

harshest environments on earth

A few climate zones may not be well represented; can we postpone a
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Rating System Proposal – Communicate four ways:1. Nameplate:2. Report:

Pmax 205 WDurability rating: .Hot-cold

★★★

Hot-dry ★★Hot-humid not ratedSnow/wind 2400 PaSalt sprayetc.

A high level summary on the naresearchers to correlate tested rexperience 20 y from now.

A detailed report can be used by engineers to more closely compare specific products

Test resultsBy Test Lab X

Standards

3. Interpretive maps

4. Climate charts th

stresses (n
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Next Steps

• A New Work Item Proposal has been 

submitted to IEC Technical CommitteWorking Group 2 as a starting point discussion 

• Some countries will identify individua

participate in rewriting this draft

• Each Task Group will create tests th

connected by this proposal

• International discussion and voting w

determine details.

19
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Summary

• The International PV Module QA Task F

developing comparative accelerated testandards

• A Rating System is necessary for the s

the QA Task Force

• The Rating System must be developed 

parallel with the Test Protocols

• The New Work Item Proposal will serve 

starting point for discussion within WG2

• All of you are welcome to join ongoing 

international discussion (~ once per mo

20

Thank you for your attention!

Sarah.Kurtz@nrel.gov
NATIONAL RENEWABLE ENERGY LABORATORY

Use

environment

“Hot‐

dry”

“Hot‐humid” “Hot‐cold” 

Cfa/open rack ★ ★ ★★★★ 

Geneva/open 

rack

★★ ★ ★★★★★ 

Tropical/rooftop BC A 

Choose your

favorite use

environment

?? ?

Climate charts – similar to the interpmaps: define relationship between czones and stress testing needed in t

Communicate meaning of tests for all climate zones, locations, 

Chart can define:• 25 years estimated service life• retention of 80% power and safe operation of 90% of module