Application of PPO, PC, PA in PV Junction Box

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The photovoltaic junction box is a connector between the solar cell array composed of solar cell modules and the solar charge control device. It is a cross-disciplinary comprehensive design that combines electrical design, mechanical design and material science.

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1. Requirements for photovoltaic junction box

 

Due to the particularity of the use of solar cell modules and their expensive value, the solar junction box must have the following characteristics:

 

1) It has good anti-aging and UV resistance;

2) Can be used in harsh outdoor environments;

3) It has an excellent heat dissipation mode and a reasonable inner cavity volume to effectively reduce the internal temperature to meet electrical safety requirements;

4) Good waterproof and dustproof function.

 

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2. Regular inspection items of junction box

 

Sealing test

Weather resistance test

Fire performance test

Fixing performance test of end feet

Connector plug-in reliability test

Diode junction temperature detection

Contact resistance detection

 

For the above test items, we recommend PPO materials for junction box body/cover parts; PPO and PC materials for connectors; PA66 for nuts.

 

3. PV junction box body/cover material

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1) Performance requirements for junction box body/cover

Have good anti-aging and UV resistance;

Lower bulk resistance;

Excellent flame retardant performance;

Good chemical resistance;

Resistance to various impacts, such as the impact of mechanical tools, etc.

 

2) Several factors for recommending PPO materials

PPO has the smallest proportion among the five major engineering plastics, and it is non-toxic and meets FDA standards;

Outstanding heat resistance, higher than PC in amorphous materials;

The electrical properties of PPO are the best among general engineering plastics, and temperature, humidity and frequency have little effect on its electrical properties;

PPO/PS has low shrinkage and good dimensional stability;

PPO and PPO/PS series alloys have the best hot water resistance among general engineering plastics, the lowest water absorption rate, and little dimensional change when used in water;

PPO/PA series alloys have good toughness, high strength, solvent resistance, and can be sprayed;

Flame retardant MPPO generally uses phosphorus and nitrogen flame retardants, which have the characteristics of halogen-free flame retardant and meet the development direction of green materials.

 

3) The physical properties of the recommended PPO material for the box body

 

 

Property

Standard

Conditions

Unit

Reference

Density

ASTM D792

23

g/cm3

1.08

Melt Index

ASTM D1238

275 /5KG

g/10min

35

Tensile   Strength

ASTM D638

50mm/min

Mpa

60

Elongation at   break

ASTM D638

50mm/min

%

15

Flexural   strength

ASTM D790

20mm/min

Mpa

100

Flexural   modulus

ASTM D790

20mm/min

Mpa

2450

Izod impact   strength

ASTM D256

1/8",23

J/M

150

UV light   exposure test

UL 746C



f 1

Surface Resistivity

IEC 60093


ohms

1.0E+16

Volume   resistivity

IEC 60093


ohms·cm

1.0E+16

HDT

ASTM D648

1.8 Mpa

120

Flame   retardant

UL94

0.75 mm


V0

 

4. Cable connector material

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1) Key requirements for connector materials

 

Have good flame retardant performance, and the flame retardant requirements are UL94 V0

The connectors generally have to be inserted and pulled out many times, so the strength and toughness of the material are required to be higher;

The outer insulating layer has excellent anti-aging and anti-ultraviolet functions, and can be used for a long time in harsh environments.

Insulation performance (insulation breakdown strength and surface resistivity) requirements are high

Low hygroscopicity, minimal impact on electrical and dimensional stability

 

2) Physical properties of recommended cable connector material PPO material

 

Property

Standard

Conditions

Unit

Reference

Density

ASTM D792

23

g/cm3

1.09

Melt Index

ASTM D1238

275 /5KG

g/10min

30

Tensile   Strength

ASTM D638

50mm/min

Mpa

75

Elongation at   break

ASTM D638

50mm/min

%

10

Flexural   strength

ASTM D790

20mm/min

Mpa

110

Flexural   modulus

ASTM D790

20mm/min

Mpa

2600

Izod impact   strength

ASTM D256

1/8",23

J/M

190

UV light   exposure test

UL 746C



f 1

Surface Resistivity

IEC 60093


ohms

1.0E+16

Volume   resistivity

IEC 60093


ohms·cm

1.0E+16

HDT

ASTM D648

1.8 Mpa

130

Flame   retardant

UL94

1.0 mm


V0

 

3) Physical properties of recommended cable connector material PC material

 

Property

Standard

Conditions

Unit

Reference

Density

ASTM D792

23

g/cm3

1.18

Melt Index

ASTM D1238

275 /5KG

g/10min

15

Tensile   Strength

ASTM D638

50mm/min

Mpa

60

Elongation at   break

ASTM D638

50mm/min

%

8

Flexural   strength

ASTM D790

20mm/min

Mpa

90

Flexural   modulus

ASTM D790

20mm/min

Mpa

2200

Izod impact   strength

ASTM D256

1/8",23

J/M

680

UV light   exposure test

UL 746C



f 1

Surface Resistivity

IEC 60093


ohms

1.0E+16

Volume   resistivity

IEC 60093


ohms·cm

1.0E+16

HDT

ASTM D648

1.8 Mpa

128

Flame   retardant

UL94

1.5 mm


V0

 

5. Nut material

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1) Key requirements for nut material

 

Flame retardant requirements UL 94 V0;

Insulation performance (insulation breakdown strength and surface resistivity) requirements are high;

Low hygroscopicity, little influence on electrical and dimensional stability;

Good surface, good gloss.

 

2) The physical properties of the recommended nut PA66 material

 

Property

Standard

Conditions

Unit

Reference

Density

ASTM D792

23

g/cm3

1.16

Melt Index

ASTM D1238

275 /5KG

g/10min

22

Tensile   Strength

ASTM D638

50mm/min

Mpa

58

Elongation at   break

ASTM D638

50mm/min

%

120

Flexural   strength

ASTM D790

20mm/min

Mpa

90

Flexural   modulus

ASTM D790

20mm/min

Mpa

2800

Izod impact   strength

ASTM D256

1/8",23

J/M

45

UV light   exposure test

UL 746C



f 1

Surface Resistivity

IEC 60093


ohms

1.0E+13

Volume   resistivity

IEC 60093


ohms·cm

1.0E+14

HDT

ASTM D648

1.8 Mpa

85

Flame   retardant

UL94

1.5 mm


V0

 


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