Solar Cell Encapsulant Composition for PID-Resistant Insulation
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Solution Overview
Problem
Existing encapsulating materials for solar cells, particularly those based on polyolefin compositions, fail to achieve a balanced combination of transparency, adhesiveness, flexibility, heat resistance, appearance, crosslinking properties, and extrusion moldability, leading to potential deformation, cracking, and increased risk of potential-induced degradation (PID) due to high voltage applications.
Innovation Solution
A specific ethylene/α-olefin copolymer composition is developed, with controlled ethylene and α-olefin content, melt flow rate, density, and aluminum content, ensuring volume resistivity within a specific range, to enhance crosslinking and electrical properties, thereby reducing deformation and PID.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyolefin based material is used as encapsulating film material, then insulation properties are improved, but transparency and adhesiveness deteriorate
Solution Approach 1:
The patent uses ethylene/α-olefin copolymer as a composite material that combines the insulation properties of polyolefin with improved transparency and adhesiveness. The copolymer structure allows for balanced performance across multiple properties that cannot be achieved with homopolymers alone.
Solution Approach 2:
The patent changes the chemical composition parameters by controlling the α-olefin content (5-30 mol%) and molecular weight characteristics to achieve optimal balance between transparency, adhesiveness, and insulation properties. This parameter optimization resolves the contradiction by finding the sweet spot in material composition.
2Temperature
If crosslinking agent is added to improve crosslinking properties, then heat resistance is improved, but deformation and cracking occur
Solution Approach 1:
The patent optimizes the crosslinking degree parameter within a specific range (5-50%) to achieve sufficient heat resistance while preventing excessive crosslinking that would cause deformation and cracking. This controlled parameter change resolves the contradiction between heat resistance and shape stability.
Solution Approach 2:
The patent uses silane coupling agents as intermediaries that provide gradual and controlled crosslinking, preventing sudden structural changes that lead to deformation. The silane acts as a mediator between the polymer chains, enabling controlled crosslinking that maintains shape integrity while improving heat resistance.
3Strength
If EVA composition is used to improve adhesiveness, then film-forming properties are improved, but harmful gases are generated
Solution Approach 1:
The patent extracts and eliminates the harmful decomposition products (acetic acid gas) by replacing EVA composition with ethylene/α-olefin copolymer. This substitution removes the source of harmful gases while maintaining the desired adhesiveness and film-forming properties through controlled composition parameters.
4Strength
If rigidity is increased to improve structural stability, then heat resistance is improved, but extrusion moldability deteriorates
Solution Approach 1:
The patent changes the molecular weight and composition parameters of the ethylene/α-olefin copolymer to achieve optimal balance between rigidity and processability. By controlling the α-olefin content and molecular characteristics, the material achieves sufficient structural stability while maintaining good extrusion moldability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The encapsulating material achieves improved balance of properties, preventing deformation and significantly reducing PID occurrences even under high voltage conditions, ensuring long-term reliability and efficiency of solar cell modules.
Implementation Method 1
a film made of an ethylene/vinyl acetate (EVA) copolymer has been widely used because it is excellent in transparency, flexibility and adhesiveness... a resin composition for an encapsulating material for solar cell using an ethylene/α-olefin copolymer excellent in a balance between rigidity and crosslinking properties
Implementation Method 2
there has been proposed the use of a polyolefin based material, particularly an ethylene based material, as an encapsulating film material, because it is also excellent in insulation properties... volume resistivity within a specific range, to enhance crosslinking and electrical properties, thereby reducing deformation and PID
Data Source
Figure 1
Figure 2(A)~2(B)
AI summary
Disclosed is an encapsulating material for solar cell comprising a resin composition, wherein the volume resistivity is from 1.0×1013 to 1×1018 Ω·cm as measured at a temperature of 100 degrees centigrade with an applied voltage of 500V in accordance with JIS K6911.