DuPont Photovoltaic Solutions Risk mitigation measures to help protect solar

assets for the long-term

5 June 2018, PV Magazine webinar

Dr. Lucie Garreau-iles, Technical Manager, EMEA

DuPont Photovoltaic Solutions

Lucie.garreau-iles@dupont.com

For over 40 years

our material innovations have led the photovoltaics industry

forward, and helped our clients transform the power of the Sun

into power for us all. Today we offer a portfolio of solutions

that deliver proven power and lasting value over the long term.

Whatever your material needs, you can count on quality

DuPont Photovoltaic Solutions to deliver the performance,

efficiency and value you require, day after day after day…

DuPont™ Tedlar®

PVF Films for Backsheet

Protecting PV

modules

DuPont™ Solamet® Metallization Pastes

Driving higher energy

conversion efficiency

DuPont Photovoltaic Materials Portfolio

© DuPont 2018 2

Over 50% of panels installed in the field since 1975 contain DuPont materials

PV LCOE

•System Lifetime

• Reliability

• Durability • System Efficiency

• Insolation

• Shading / Dusting

• Low-light Performance

÷

System

Revenue

Return

Lifetime Power

Output (kWh)

System

Cost ($)

Levelized Cost of Energy (LCOE)

• Modules

• BoS

• Installation

• Financing

Initial Cost

Operating

Cost • O&M

• Interest

© DuPont 2018 3

The Backsheet is Critical for Protecting the PV Panel

Ultra Violet (UV)

• Transmitted

• Reflected

Physical Protection

• Abrasion

• Impact

Corrosive Environment

• Atmospheric chemicals

• Ammonia

• Marine environment

Stress Environment

• Peak

• Cycling

Temperature

• Humidity

• Precipitation

• Condensation

Moisture

Backsheet must provide reliable electrical protection of module

over the expected lifetime (and beyond)

Inner Layer

Middle Layer

Outer Layer

Backsheet structure

© DuPont 2018 4

Global DuPont Field Surveys (2017)

Source: DuPont Field Module Program 2017 analysis

Note: All percentage numbers are based on MW

• Surveyed: 286 Installations in North America, Europe & Asia Pacific

• Figures reported below: 45 module manufacturers, 1,047 MW > 4.2 MM modules

• Range of exposure: from newly commissioned modules to 30 years in service

• From multiple climates

Backsheet is one of the main components affected

5

22.5% of panels affected

© DuPont 2018

Climatic Sensitivity vs. Polymer Degradation

Source: DuPont Field Module Program 2017

Note: All percentage numbers are based on MW

Higher temperature seems to accelerate degradation rates of the

encapsulant and backsheet

Temperature

6

-

5,0

10,0

15,0

20,0

25,0

Hot Tropical Temperate

Def

ects

in %

Backsheet

Encapsulant

© DuPont 2018

Material Sensitivity vs. Backsheet Defect Rates

Defect rate as a function of backsheet used

PA = Polyamide

PVDF = Polyvinylidene Difluoride

PET = Polyethylene Terephthalate

FEVE – Fluoroethylene Vinyl Ether

* No field data available

© DuPont 2018 7

Types of Degradation Affecting the Backsheet

Source: DuPont Field Survey 2016

© DuPont 2018 8

Cracking and delamination represent serious threats to the

electrical protection of the panel (59% of defects).

Yellowing is an indicator that the polymer has started to degrade

5%

54%

3%

38%

Delamination Cracking

Air side yellowing Front side Yellowing

DuPont Sequential Stress Test (MAST) vs. Field

IEC 6125 MAST (DuPont)

9 © DuPont 2018

Sequential tests correlate better with degradation seen in the field • Combine most important stress factors

• Use stress levels / dosages that match field exposures

• Accelerate with highest temperature but • Do NOT produce degradation not found in the field

Stress PET PVDF PA Tedlar® Comment

Field Yellowing

Mech Prop Loss

Cracking

Cracking

Front Side

Yellowing

Yellowing

Mech Prop Loss

Cracking

Low

defects

Effects of simultaneous

and sequential stresses

Damp Heat (1000 hrs) Slight Yellowing No Change Mech Prop Loss No Change Misses UV degradation

UV (4000 hrs) Yellowing

Mech Prop Loss No Change Mech Prop Loss No Change

Misses hydrolysis and

moisture

DH/UV/TC (MAST

Sequential Test)

Yellowing

Mech Prop Loss Cracking

Cracking

Front Side Yellowing

Yellowing

Mech Prop Loss Cracking

No Change Combines key stresses Gives best correlation

-25%

-20%

-15%

-10%

-5%

0%

5%

10%

15%

20%

25%

30%

20% 22% +10% +20% 20 y

30 y

Efficiency (18%)

Power Output (1500kWh/kWp)

Lifetime (25 years)

LCOE Sensitivity

• Irradiation

• Bifacial

• Tracking

• PERC

• HTJ

• Panel packaging

• BoS components

• Materials

2.5 USD cents/kWh

LCOE

Variation

© DuPont 2018 10

Summary

Think in terms of EUR/kWh rather than EUR/Wp - reliability & durability are key

IEC certification is not designed to predict the long-term performance of the panels

Consider alternative sequential testing approach (MAST) to better simulate the field

stress conditions and mimic actual defects observed

Consider field-proven materials and panel construction, UV and thermal resistant –

especially in harsh climatic and temperature-sensitive environments

Work with trusted partners up and down the value chain who have a proven field track

record.

© DuPont 2018 11

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