cSi Solar Panel Failures: From Chamber Testing to Field Installations

Shuying Yang/K Whitfield 4/7/2015 PVMC Workshop, Orland, FL

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Abstract Solar panels/modules are designed for 25 years’ warranty

(extending to 30 years for some ambitious module manufacturers). Extensive qualification is done at module component level and also extensive reliability/durability testing are performed on module level. Still significant field failures are experienced for the industry. This short presentation is meant to have a brief review on what might go wrong from the accelerated stress testing to field installations. This is also meant to stimulate the interest for the industry to look for what is the gap of the accelerated testing to the real field applications, and potentially to predict the field performance based on stress testing.

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Outlines §  What might go wrong §  Typical Accelerated Testing related failures

•  DH/TC/PID/MLT §  Typical Field Failures

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What Might Go Wrong: Module Components §  Glass: Corrosion/Yellowing/Cracking/PID* §  Encapsulant: Yellowing/Delam/Transmission Loss/Snail Trail*/PID* §  Cell: Corrosion/Cracking/Snail Trail/Hotspot/PID §  Conducting Ribbon: Corrosion/Poor Soldering §  Flux: Interaction to Cell (Cell Corrosion)/Poor Soldering §  Backsheet: Delamination/Cracking/Yellowing/Scratching/Burning §  Jbox: Diode, Cable, Connector, Sealing, Adhesion to JBox §  Sealant: Adhesion to Jbox/Backsheet/Frame §  Pottant: Compatibility with Jbox/Thermal Expansion §  Frame: Mounting integrity §  Labels/Ink: Delamination/Weatherability

*Contributing Factor

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Typical Accelerated Testing §  IEC61215/IEC61730/UL1703 and Industrial Requirements

•  Damp Heat (85°C/85%) •  Temperature Cycling (-40°C to 85°C) •  Humidity Freeze •  Mechanical Load Testing (MLT: 2400Pa or 5400Pa or other

loading) •  Potential Induced Degradation (PID)

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Typical DH (extended) Related Failures §  Cell Corrosion §  Connector Crack §  Backsheet Crack §  EVA/Glass Delam §  Bussing ribbon corrosion

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Typical DH Testing Failures §  Glass Corrosion

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Temperature Cycle Related Failures §  Ag Finger Defects §  Cell Cracks §  Ribbon/cell soldering defects

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Typical PID Testing Failures §  Dark Cells (Severe Pmax Drop)

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Mechanical Load Testing Failures §  Cell Crack §  Frame Failures (deformed/torn/permanent warpage)

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Observed Field Failures §  By 2014 Failure Summary:

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Field Failures §  Glass Shattering

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Ag Finger Corrosion §  Ag finger color change

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Backsheet Burning §  Backsheet Burning due to shunting cell hotspots:

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Backsheet Yellowing §  Wrong material choice

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Hotspot §  Poor Soldering Hotspot: Leads to glass shattering

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Jbox Detachment §  Wrong sealant material choice, ended with aged/delam

sealant to backsheet

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Cell Crack/ Module Delam §  Delam patterns along the crack lines §  Corrosion/Delam along the Ag fingers near cell edges

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Module Delam §  Cell side delam §  Backsheet side delam

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Jbox Related; Diode Failures §  Shorted diode: burned

Jbox §  Burning Connectors:

§  Jbox failure due to loose screw connection

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Fire Damage §  Roof Top Mounting

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ARC Coating Layer Degradation §  Uneven cell colors

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Mounting Sealant Failures §  12 years mounting

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Damaged Frame by Snow §  Frame Design: Strong enough for snow?

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Snail Trail §  Oxidation of the Ag

finger due to cell crack

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More Snail Trails – Cell crack

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Encapsulant Browning §  EVA browning in the middle of the cell, perimeter showed

photo bleaching

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Gaps: Chamber to Field §  Gaps Observed

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References §  Ref: IEA-

PVPS_T13-01_2014_Review_of_Failures_of_Photovoltaic_Modules

§  Internet §  Private Communication: “Disaster Deck” by Kent Whitfield §  Santa Rita Jail Field Trip (~10 years installation)

Thank You ! syang3@sunedison.com; kwhitfield@sunedison.com