General Specifications about Solar Encapsulant

Its main function:

–

Holds solar cells in place.

–

Isolates the cells from moisture, air, and environmental factors.

–

Efficiently transmits light to the cells while maintaining transparency.

–

Shock absorption and protects the cells from mechanical damage.

Most commonly used materials:

–

EVA (Ethylene Vinyl Acetate – most commonly used.

–

POE (Polyolefin Elastomer) – most commonly used in bifacial panels.

Distinctive properties:

–

High transparency.

–

Excellent UV resistance.

–

Long-term thermal stability.

–

Does not discolor or yellow over time.

Examples of specifications for some types of Solar Encapsulant

FY08P/ FY10P POE FILM

Technical Specification

Properties

Units

Test Method

Parameter

EPEU307

EPET306

Nominal Thickness

mm

ASTM F2251

0.45~0.75

Unit Weight

g/m2

FEIYU METHOD

±20

Roll Length

m/roll

100/150/200

Width

mm

Customization         +3

Density

g/cm3

ASTMD792

0.88

Density

Tensile

MD

Mpa

ASTM D882

22

TD

MPa

20

Elongation

MD

%

ASTM D882

500

TD

%

500

Shrinkage Rate(120℃,3min)

MD

%

ASTM D882

<3.0

TD

%

<1.5

UV-Cutoff Wave Length

nm

~~

250

360

Light Transmittance

1100nm-380nm

%

ASTM D1003

>90

>90

380nm-290nm

%

>80

<30

UV Resistance (32kWh/m2) Δb*

~

ASTM G154

1.4

0.5

UV Resistance (32kWh/m2) ΔT%

~

2

1

Damp Heat Resistance (85% RH, 85°C 1000h)

ΔY

IEC 61215

<2

<2

Damp Heat Resistance (85% RH, 85°C 1000h)

ΔY

<3

<3

Gel Content

%

>75

Gel Content

Volume Resistivity

Ω.cm

ASTM D257

>1*1017

Volume Resistivity

Peeling Strength from Glass

N/cm

ASTM D903

>80

Peeling Strength from Glass

Peeling Strength from BS

N/cm

ASTM D903

>80

Water Absorption

wt%

ASTM D570

0.12

Inner Packing & Shift Life

~

~

Plastic Bag, 9
months

Inner Packing & Shift Life

Nominal Temperature:145-150℃

Platen Tamperature:143-153℃

Vacuum Range:<60mba

Cure Time: 10-15 min

Evacuation Time:3-4min

Applied Bladder Pressure:910mbar

EPE (EVA-POE-EVA) FILM

EPEU307 & EPET306 GRADES

Technical Specification

Properties

Units

Test Method

Parameter

EPEU307

EPET306

Total Thickness (Tolerance: ±0.05%)

mm

UPS method

0.40 ~ 0.90

Total Width

mm

Scale

Up to 1300

Thermal Shrinkage (MD)

%

On solar glass (5 min, 125^OC)

≤ 3

≤ 3

Water Vapor Transmission

g/m² /24h

ASTM F1249

≤ 5

≤ 5

UV Resistance (120kWh/m2)

ΔYI

ASTM G154

≤ 5

≤ 5

Humidity and Heat Resistance

ΔYI

ASTM E313

≤ 5

≤ 5

Degree of Cross-linking (Gel Content)

%

Soxhlet Method Lamination (14 min,145^OC)

≥ 70

≥ 70

Adhesion to Glass (With Backsheet)

N/㎝

ASTM D 903

≥ 60

≥ 60

Adhesion to Backsheet

N/㎝

ASTM D 903

≥ 60

≥ 60

Ultimate Elongation (Cured)

%

ASTM D 638

≥ 500

≥ 500

Tensile Strength (Cured)

MPa

ASTM D 638

≥ 10

≥ 10

Optical Transmittance (380nm-1100nm)

%

ASTM D1003

≥ 90

≥ 90

UV Cut-off Wave Length (290nm-380nm)

%

ASTM D1003

≤ 30

≥ 70

Component Power Loss

%

IEC G2804

≤ 5

≤ 5

Dielectric Strength

kV/mm

ASTM D149

≤ 28

≤ 28

Volume Resistivity (Cured)

Ω*cm

ASTM D 257

≥ 1*10¹⁶

≥ 1*10¹⁶

Lamination Recipe

Lamination Parameters

Unit

Single Chamber

Double Chamber

Temperature

OC

145 – 150

145 – 150

Vaccum Time

min

4 – 6

4 – 6

Lamination Time

min

8 – 12

8 – 12

Comparison between EVA and POE in Solar
Panels

Feature

EVA (Ethylene Vinyl Acetate)

POE (Polyolefin Elastomer)

Market Presence

Very common, used in over 70% of modules

Less common, but gaining popularity

Transparency

High

High

Moisture Resistance

Moderate

Very high

Thermal Stability

Good

Better than EVA

Chemical Resistance

Acceptable

Excellent

Suitability for Bifacial Modules

Not ideal due to light absorption

Excellent, allows more light
transmission

Yellowing Over Time

Higher tendency

Lower tendency

Cost

Lower

Slightly higher