Solar Cell Encapsulant Sheet with Silane Crosslinking
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Solution Overview
Problem
Ethylene-vinyl acetate copolymer-based sheets for solar cell encapsulants face challenges with increased moisture permeability, reduced transparency and flexibility, and the need for a crosslinking process, which affects durability and productivity in solar cell modules.
Innovation Solution
A sheet comprising an ethylene-based polymer with a melting point of 90° C or higher, an ethylene-vinyl acetate copolymer with a vinyl acetate content ratio of 19% to 40% by mass, and a silane coupling agent with an amino group, which enhances adhesiveness and stability without requiring a crosslinking treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the vinyl acetate content ratio in ethylene-vinyl acetate copolymer is increased to improve transparency and adhesiveness, then transparency and adhesiveness are improved, but moisture permeability increases
Solution Approach 1:
The patent uses a composite material system consisting of ethylene-vinyl acetate copolymer combined with silane coupling agent and peroxide. The silane coupling agent forms a crosslinked network structure that reduces moisture permeability while maintaining the transparency and adhesiveness provided by the vinyl acetate units in the copolymer.
Solution Approach 2:
The patent optimizes the vinyl acetate content ratio within a specific range (20-40%) rather than using high ratios, and combines this with controlled crosslinking degree parameters. This parameter optimization achieves the balance between transparency/adhesiveness and moisture barrier properties.
2Temperature
If a crosslinking process is applied to obtain heat resistance, then heat resistance is improved, but production time increases and productivity decreases
Solution Approach 1:
The silane coupling agent is incorporated into the copolymer matrix during sheet formation in advance, so that the crosslinking reaction can proceed rapidly during the lamination process without requiring separate prolonged crosslinking treatment. This preliminary incorporation enables fast in-situ crosslinking.
Solution Approach 2:
The patent replaces traditional prolonged thermal crosslinking processes with a rapid crosslinking system using silane coupling agent and peroxide that activates during lamination. This substitution reduces crosslinking time from hours to minutes, significantly improving productivity while maintaining heat resistance.
3Object-affected harmful factors
If the vinyl acetate content ratio is decreased to reduce moisture permeability, then moisture permeability is reduced, but transparency and flexibility decrease
Solution Approach 1:
The patent creates a composite where silane coupling agent molecules form a three-dimensional crosslinked network within the copolymer matrix. This network structure provides the moisture barrier function, allowing the copolymer to maintain higher vinyl acetate content (20-40%) for transparency and flexibility without excessive moisture permeability.
4Object-affected harmful factors
If the vinyl acetate content ratio is decreased to reduce moisture permeability, then moisture permeability is reduced, but adhesiveness decreases
Solution Approach 1:
The silane coupling agent forms crosslinked structures that enhance adhesion between the encapsulant and solar cell surfaces. The crosslinked network provides mechanical interlocking and chemical bonding, compensating for the reduced adhesiveness that would result from lower vinyl acetate content, while simultaneously providing moisture barrier protection.
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 solution provides excellent transparency, flexibility, and adhesiveness, improving the durability and productivity of solar cell modules while maintaining stability and reducing the need for heating treatments.
Implementation Method 1
a silane coupling agent having an amino group
Implementation Method 2
an ethylene-based polymer having a melting point of 90° C. or higher
Data Source
AI summary
Provided is a sheet for a solar cell encapsulant containing (A) an ethylene-based polymer having a melting point of 90° C. or higher and containing an ethylene-derived constituent unit as a main component; (B) an ethylene-vinyl acetate copolymer having a vinyl acetate-derived constituent unit at a content ratio of from 19% to 40% by mass; and (C) a silane coupling agent having an amino group. The sheet for solar cell encapsulant has the excellent transparency and flexibility possessed by an ethylene-vinyl acetate copolymer. Furthermore, a crosslinking treatment is substantially unnecessary, and adhesiveness and adhesion stability that are appropriate for practical use are obtained.