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Fielded PV Module Condit

27th EU PVSEC and IEA PVPS Task 13 Subtask 3.2 

Corinne E. Packard

Colorado School of Mines/National Renewable Energy LaboratoryJohn H. Wohlgemuth, Sarah R. Kurtz, Ulrike Jahn,Karl Berger, Thomas Friesen, Marc KoentgesNREL/PR-5200-56781

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Allia
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Cataloging Module Condition by Visua

The NeedUnderstanding PV module aging in 

different climate zones is crucial for predicting lifetime, but no accepted 

tool for the collection of largescale, consistent data on module degradation exists

The ChargeIEA PVPS Task 13: Performance and Reliability of PV Subtask 3.2: Collecting Failures and Adapting Testing Failure Mechanism for PV Modules (Lead: Marc KoenNREL’s Role- Create an inspection tool for documvisually observable defects in PV modules

NREL/PIX 11060, N
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Connecting visually observed defects to 

• Important for prediction of lifetime and setting 

Visual 

Observations

Electrical 

Measuremen

Establish Causality

Mono-Si 639

IV Par

Pmax Isc 

632 

Degradation Rate (%/year)

Dirk Jordan, Thursd
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Quantification and standardization are n

Describe the problems 

with this module

• Brown with one spot worse 

than others

• One cell is orange• Minor and major discoloration• Overheating over the junction 

box

• Severe encapsulant yellowing• ...etc.
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Overview of Visual Inspection DaCollection Tool

• Uses IEC/UL standard terminology• Attempts to balance collection of sufficient det

failure mode evaluation against minimizing rectime per module

• Consists of 14 sections- based on module com

• Long form & short form evaluations

Development of a Visual Inspection Data Collection Tool for Evaluation of Fielded PV Module ConditionC.E. Packard, J.H. Wohlgemuth, S.R. Kurtz

Additional detail can be found in the 

full NREL report TP-5200-56154
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Development of the Inspection 

• Developed by members of NREL’s PV Reliab

(led by Sarah Kurtz) with input from IEA Colla

• Ulrike Jahn (TÜV Rheinland Immissionsschutz und Ene

Germany), Karl Berger (Austrian Institute of Technology(Scuola Universitaria Professionale della Svizzera Italian

(Institut fuer Solarenergieforschung GmbH Hameln/Emm

• Evaluated with a total of >60 modules from 3 

• Broad range of technologies, vintages, and field exposu

• Based on SYMPTOMS, not DIAGNOSES

• Unexpected degradation can’t be captured if you don’t k

looking for
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1. System Data
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2. Module Data

As indicated on nameplate
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3. Rear-side Glass

Chips >10, module edge
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4. Backsheet

LargeBubble

Wavy (Delamina

Major Discoloration Peeling Texture (record as delamination)
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4. Backsheet- Detail on Damage Type
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5. Wires/ Connectors

Cracked/disintegrated ins

Animal bites/marks

http://www.gutachten.streib.de/bilder/index.html
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5. Wires/ Connectors

Tyco Electronics

MC3 MC4

Tyco Solarlok
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6. Junction Box
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7. Frame Grounding
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8. Frame

Frame joint separation
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9. Frameless Edge Seal

White o

Sealan

Edge 

Bead of Silicone Around Module Edges

Not an Edge Seal- NOT Applicable
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9. Frameless Edge Seal
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10. Glass/Polymer (front)

L(
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10. Glass/Polymer (front)

Lightly soiled 

Sanchez-Friera et a
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11. Metallization- Clarification of Termi

Up to 4 levels of metallization and interconnects considered:1. Gridlines/Fingers- finest level of metallization, <1mm thick2. Busbars- connect gridlines/fingers within a single cell; often ob

interconnect ribbon

3. Cell Interconnect Ribbon- connects multiple cells into a string4. String Interconnect- connects multiple strings of cells

On an individual silicon cell

Gridlines

Busbars Cell Interconnect R

String Interconnect

On a silicon module

Note: The condition of the busbars 

due to the overlap of the cell int

For thin film modulesConsider function of metallization; generally will not use all 
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11. Metallization

Gridli
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11. Metallization

Dark Discoloration on S
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12. Silicon Module: Cells
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12. Silicon Module: Discoloration

Dark discoloration at cell edges, between cells, and over gridlines and busbars Light discoloration at cell center Light and 

one indivothers
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12. Silicon Module: Discoloration

No discoloration Discoloration over Center Of Cells
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PHOTOVOLTAIC POWER SYSTEMS PROGRAMME12. Silicon Module: Damage

Worm ma
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12. Silicon Module: Delamination

Semiconductor/Encapsulant delamination

near edges

Sanchez-Friera et al. Prog. Photovolt: Res. Appl. 2011

Semiconductor/Encap

near b
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Major discoloration

Mi

Major discoloration/spotted degradation/no pattern
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PHOTOVOLTAIC POWER SYSTEMS PROGRAMME13. Thin Film Module

SmaPoss

Absorber delamination
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14. Electronic Records
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Preliminary Data

Site 1: Tempe, Arizona, USA

49 modules

83% Silicon (mono + multi)

18% Thin film

Site 2: New D

14 mod

17% Silicon (m

83% Th
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Summary & Conclusion

• Data collection tool has been created and 

available for use

• Long form and short form data collection to

available, along with report detailing intendcollection procedures

• Collection of uniform, detailed data from m

climate zones is one part of understanding degradation and failure

Development of a Visual Inspectiofor Evaluation of Fielded PV ModuC.E. Packard, J.H. Wohlgemuth, S.R

Additional detail can be fo

full NREL report TP-520