General Specifications about Solar Backsheet

The backsheet in solar panels is the layer covering the back of the solar panel and is an important part of its structure, protecting the solar cells and internal components.

The most important functions of the backsheet

–

Electrical insulation to protect the system from electrical leaks.

–

Prevents moisture penetration to protect the solar cells.

–

Withstands ultraviolet radiation for extended periods without deteriorating.

–

Improves the long-term efficiency of the solar panel.

Common types of backsheet:

–

White backsheet: Popular because it reflects heat.

–

Black backsheet: Used for aesthetic purposes but absorbs more heat.

–

Transparent backsheet: Used in some bifacial module designs.

Examples of specifications for some types of Solar Encapsulant

Back sheet of solar panel (TYPE: RO-PET)

Technical Specification

Properties

Units

Parameter

Color

White or Black

Thickness

mm

320 ± 20

Length

m/roll

150

Width

mm

Customization0/+7

Tensile strength

Mpa

MD ≥100, TD≥ 100

Elongation at break

Mpa

MD ≥100, TD≥ 80

Heat shrink 150℃, 30Min)

% <

1.5

PVDF film/PET film peeling force

≥ 4.0 N/cm

BS/EVA peel strength ≥

60N/1.5cm

Inner reflectance

≥ 80%

Falling sand test

≥160L

Water vapor transmission rate 38 ℃, 90% RH

1.5g/m2

Breakdown voltage

≥ 20KV

Partial discharge

≥ 1500 VDC

CTI

≥ 600V

Thermal index TI

120 ℃

Testing environment conditions: temperature 23 ± 2 ℃ ,
humidity 50 ± 15% RH

Excellent properties

–

Designed with a PVDF/Adh/PET/Coating Structure

–

Tensile Strength of ≥100 MPa and Elongation at Break ≥80%

–

High Breakdown Voltage of ≥18 kV and Exceptional Partial Discharge Voltage of 1000V or 1500V

–

Excellent Light Transmittance (≥85%) and Reflectivity (≥75%)

–

Outstanding Weather and Thermal Stability

Back sheet of solar panel (TYPE: PET-KPC)

Technical Specification

Model

Colors

Aggregate thickness

Breadth

Structure

Thickness of each layer (Standard thickness)

Inshine 301Y (1000V)

White, black

287.5µm (0, +5%)

≤1300mm

PVDF//Adh//PET//Coating

22. 5µm//10µm//250µm //5µm

Inshine 301H (1500V)

White, black

312.5µm (0, +5%)

≤1300mm

PVDF//Adh//PET//Coating

22. 5µm//10µm//250µm //5µm

Inshine301Y-T (1000V)

Transparent

287.5µm (0, +5%)

≤1300mm

PVDF//Adh//PET//Coating

22. 5µm//10µm//250µm //5µm

Inshine301H-T (1500V)

Transparent

312.5µm (0, +5%)

≤1300mm

PVDF//Adh//PET//Coating

22. 5µm//10µm//250µm //5µm

Test project

Unit

Quoted standard

Specification value

Appearance

—

—

Without impurities, bubble, fold, etc.

Tensile strength

MPa

GB/T 13542.2-2009

TD≥100; MD≥100

Elongation at break

%

GB/T 13542.2-2009

TD≥80; MD≥100

Hot-shrinkage rate (150°C-30min)

%

GB/T 13542.2-2009

-0.2 ≤TD ≤0.2; MD ≤0.6

Coating adhesion

Grade

GB/T 9286-1998

Lv. 0

Peel strength with EVA

N/cm

GB/T 2790-1995

≥60

Breakdown voltage

KV

GB/T 1408.1-2016

≥18

Partial discharge voltage

VDC

IEC 60664-1-2007

Inshine301Y: 1000V

Inshine301H: 1500V

Water vapor transmittance 38°C-90%RH

g/(m² day)

GB/T 26253-2010

<2.0

Volume resistivity

Ω.CM

GB/T 31838-2-2019

≥1.0*10¹⁵

Reflectivity(400nm-1100nm)

%

ASTM E424-2015

≥75% (Write KPC)

Light transmittance (400nm-1100nm)

%

ASTM E424-2015

≥85% (Transparent KPC)

Boiling water treatment

Appearance detection

—

GB/T 17748-2008

No delamination, no foaming, no cracking

Peel strength with EVA

N/cm

≥40

Cold and heat cycle test

Appearance detection

—

IEC 61215-2-2016

No delamination, no foaming, no cracking