Driving Solar Success COLLABORATION Sponsored by D882 / ASTM D5870 < = 2.0 > = 70 > = 70 No cracking or delamination 5MW ground mount installation — United Kingdom

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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

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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

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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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• 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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