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Copyright © 2015 DuPont. All rights reserved. The DuPont Oval Logo, DuPont™ and Tedlar® are trademarks or registered trademarks of E.I. du Pont de Nemours and Company or its affiliates.
340/335/330/320 Wp
Heliene 72M
PV Module Backsheet Component Safety and Performance
Items Test Methods Specification
Tensile Strength (MPa) ASTM D882> = 100 (TD) > = 100 (MD)
Elongation at Break (percent) ASTM D882> = 100 (TD) > = 100 (MD)
Dimensional Stability (percent, 150 degrees C, 0.5h) ASTM D882< = 1.0 (TD) < = 1.0 (MD)
Breakdown Voltage (kV) ASTM D257 > = 20
WVTR (g/m² day, 37.8 degrees C, 100% RH) ASTM F1249 < = 2.5
Interlayer Peeling Strength (N/cm) ASTM D1876 > = 4
Peeling Strength with EVA (N/cm) ASTM D903 > = 40
Damp Heat (85 degrees C, 85%RH, 1000hrs) – Color Change delta b – Elongation Retention (%) – Appearance
ASTM E1171 ASTM E308 / ASTM D2244
ASTM D882 / ASTM D5870
< = 2
> = 70 No cracking or delamination
UV Exposure Irradiance of 0.55 W/m² at 340nm (61 W/m²) using a xenon lamp with a daylight filter (outer layer). Exposure is 4200 hours (260 kWh/m² total UV (300-400 nm)) – Color Change delta b – Elongation Retention (%) – Tensile Retention (%) – Appearance
ASTM G155
ASTM E308 / ASTM D2244 ASTM D882 / ASTM D5870 ASTM D882 / ASTM D5870
< = 2.0 > = 70 > = 70
No cracking or delamination
5MW ground mount installation — United Kingdom
600kW rooftop installation – Peterborough, Ontario, Canada
600kW rooftop installation — Toronto, Canada
Heliene Inc. is the leading manufacturer of solar photovoltaic modules in Canada. The facility in Sault Ste. Marie, Ontario, located at the heart of the Great Lakes, was the first of its kind to have started in Canada in 2010. Incorporating highly robotized equipment with the ingenuity of Canadian talent has allowed Heliene to prosper as one of the most prevalent solar module manufacturers in Canada.
BAA/ARRA Compliant
All Heliene modules manufactured in the Ontario, Canada and St. Paul, Minnesota facilities comply with the Buy American Act and the American Recovery and Reinvestment Act.
2015 U.S. Army PV Module Backsheet Specifications
Establishing a new, higher quality standard for improved module safety, performance and durability
Heliene modules are approved by the U.S. Corps of Engineers for their commercial and utility scale solar projects
Product Preview
• Full range of products• 36-96 cell for off-grid or
grid-tie applications• Power output range:
160Wp – 450Wp• 36 cell Class 1 Division
2 products for off-grid applications and hazardous locations
• 40mm double-walled anodized aluminum alloy frame for the most rigid and robust product on the market
• Full product traceability, automated manufacturing process can track material and labour inputs into every module
• ISO 9001 approved
First U.S. Military Installation Underway
• 2.5MW ground mount installation in Dugway, Utah• Military requirements:
– 320W power output – Adherence to new, higher quality backsheet
specification criteria• Desert environment conditions• Heliene 72M modules selected for installation• Tedlar® PVF film-based backsheets specified
– Tedlar® film is the only backsheet material proven to protect solar modules for 30+ years in all weather conditions
Installations
Tried, Tested and True
Rated as Tier One manufacturer by Bloomberg New Energy Finance
Projects with Heliene have been funded by large financial institutions:
Several third-party audits on products and facilities:
Meeting Quality Requirements for U.S. Military PV Installations
Overview
Heliene collaborated with DuPont to perform field investigations and failure mode effect analysis.
Initial year of operation 2011• Modules Heliene• Service time 4 years• Location North America• # of modules 48 x 4• System size 4 x 10kW• Mounting configuration Ground mounted• Date of inspection May 15, 2015• Fixed tilt or tracking 2 axis• Backsheet single sided PVDF-based• Technology mono
Site Inspection Summary • Four systems exhibited PVDF-based backsheet cracking and delamination at various stages of
degradation (average 57% after 4 years of operation)
• Cracking appears to be uniform and consistent in the vertical or longitudinal direction of the module
• The machine direction of backsheets are typically aligned in the vertical direction of a module
• PVDF films have inherent weak TD elongation strength
• Processing or service environments may highlight
inherent TD weakness in PVDF film manifested as
a crack in the film's MD direction
Module Vertical Direction Backsheet Film Machine Direction
DuPont Confidential © DuPont 2015 6
Site Inspection Summary
• Four systems exhibited PVDF-based backsheet cracking and delamination at various stages of degradation (average 57% after 4 years of operation)
• Cracking appears to be uniform and consistent in the vertical or longitudinal direction of the module
• The machine direction of backsheets are typically aligned in the vertical direction of a module
• PVDF films have inherent weak TD elongation strength
• Processing or service environments may highlight inherent TD weakness in PVDF film manifested as a crack in the film’s MD direction
4 Identical 10kW Installations
Backsheet/Cracking Delamination Percentage
System 1 85.4System 2 41.7System 3 20.8System 4 33.3Average 57.2
PVDF-Based Backsheet Cracking and Delamination
• Occurs consistently in the vertical direction• Initial crack formation followed by tear propagation and subsequent
backsheet delamination
PVDF Based Backsheet Cracking and Delamination • Occurs consistently in the vertical direction
• Initial crack formation followed by tear propagation and subsequent backsheet delamination
Initial Crack
DuPont Confidential
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Final Delamination
Propagation Tear
Initial Crack
% Elongation After DH (85°C, 85%RH)
Literature Reference
• Effect of TiO2 on Morphology and Mechanical Properties of PVDF/PMMA Blend Films Prepared by Melt Casting Process J. AAPL. POLYM. SCI. 2014
• The publication indicates PVDF/PMMA polymer chains can readily separate in the TD direction and break
Summary
• Four 10kW istallations surveyed had 21% to 85% (average 57%) of modules with PVDF-based backsheet cracking & delamination after 4 years.
• PVDF film has been found to have poor mechanical properties (low elongation) in the transverse direction (TD) of the manufactured film. The low TD elongation is attributed to the alignment of the polymer chains during film manufacturing.
• The poor mechanical properties were found in our testing of seven commercial PVDF films used in commercial PV backsheets.
• Poor mechanical properties have led to cracking of the outer PVDF-based backsheet layers in sequential stress testing and observed in the field.
Single sided PVDF/PET/EVA backsheet shows cracking in sequential mini module accelerated testing and outdoor exposure
• •
• 0 2x(DH1000/TC200)
DuPont Confidential
4 years outdoors
• PVDF/PET/EVA outer layer shows cracking in sequential accelerated test consistent with full size module outdoors
• The Tedlar®-based backsheet control shows no cracking in either test
11 © DuPont 2015
2x(DH1000/TC200)
4 years outdoors
• PVDF/PET/EVA outer layer shows cracking in sequential accelerated test consistent with full size module outdoors
• The Tedlar®-based backsheet control shows no cracking in either test
Module Analysis - EL & Thermal Images Unexposed Exposed
• El image of exposed module identifies several cells from edge of wafer brick, no cracks • Thermal image of exposed module indicates some thermal non-uniformities • EL of unexposed module indicates a few fine line interruptions possible from soldering
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Module Analysis
Both modules passed wet leakage >23.8 MOhms.
99.76 MOhms Unexposed
81.91 MOhms Exposed
FTIR spectroscopy confirms PVDF outer surface
Exposed module has significant delamination of PVDF outer surface
DuPont Confidential
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Module Analysis—EL & Thermal Images
• El image of exposed module identifies several cells from edge of wafer brick, no cracks
• Thermal image of exposed module indicates some thermal non-uniformities• EL of unexposed module indicates a few fine line interruptions possible
from soldering
Unexposed Exposed
Module Analysis
• FTIR spectroscopy confirms PVDF outer surface• Exposed module has significant delamination of PVDF outer surface
Sequential Test Results Consistent with Field Failure Observations
Single sided PVDF/PET/EVA backsheet shows cracking in sequential mini module accelerated testing and outdoor exposure
• PVDF/PET/EVA outer layer shows cracking in sequential exposure tests consistent with outdoor exposure
• The Tedlar®-based backsheet control shows no cracking in either test
*1000th UVA = 65kWh/m²
Single sided PVDF/PET/EVA backsheet shows cracking in sequential mini module accelerated testing and outdoor exposure
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DuPont Confidential
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• PVDF/PET/EVA outer layer shows cracking in sequential exposure tests consistent with outdoor exposure.
• The Tedlar®-based backsheet control shows no cracking in either test.
• 1000h UVA= 65 kWh./n1' 12 © DuPont 2015
4 years outdoors
DH1000/UVA1000*/TC200
Key Learnings from Heliene Site Inspections
Buy American Act / ARRA Compliant
About Heliene
: COLLABORATIONDriving Solar Success
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