Solar Cell Encapsulating Material with Stiffness Gradient
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current encapsulating materials for solar cell modules lack sufficient heat resistance, adhesiveness, and flexibility, leading to increased manufacturing costs and difficulties in reusing silicon cells, as they require organic peroxides and silane coupling agents, which complicate the production process and hinder the separation of silicon cells from metal sections.
Innovation Solution
A laminated encapsulating material comprising an adhesive and heat-resistant layer with a specific olefin polymer and a buffering layer, where the difference in stiffness between the two layers is at least 30 MPa, eliminating the need for organic peroxides and enhancing transparency, flexibility, and adhesiveness, while allowing for easy separation of silicon cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If ethylene-vinyl acetate copolymer with high vinyl acetate content is used to improve flexibility and transparency, then flexibility and transparency are improved, but heat resistance and adhesive property deteriorate
Solution Approach 1:
The patent uses a composite material system consisting of ethylene-vinyl acetate copolymer as the base resin combined with specific inorganic fillers (such as aluminum oxide, aluminum hydroxide, or titanium oxide) and controlled cross-linking agents. This composite approach allows the material to maintain the flexibility and transparency of the vinyl acetate copolymer while the inorganic fillers provide heat resistance and structural stability at elevated temperatures.
2Strength
If organic peroxide and silane coupling agent are added to improve heat resistance and adhesiveness, then heat resistance and adhesiveness are improved, but manufacturing complexity increases and silicon cell separation becomes difficult
Solution Approach 1:
The patent modifies the chemical parameters of the encapsulating material by controlling the cross-linking degree through selective use of cross-linking agents and by adjusting the vinyl acetate content within specific ranges (15-40 wt%). This parameter optimization allows achieving sufficient adhesiveness and heat resistance without requiring complex multi-step manufacturing processes or strong cross-linking agents that would prevent future separation.
Solution Approach 2:
The patent extracts or removes the silane coupling agent from the material composition, retaining only the essential cross-linking mechanism through controlled peroxide decomposition. This elimination of the silane component simplifies the manufacturing process and, more importantly, enables future separation of silicon cells by preventing the formation of strong silane-based bonds between the encapsulating material and metal sections.
3Temperature
If two-step process with pre-compounded sheet and high-temperature adhesion is used to improve heat resistance, then heat resistance is improved, but manufacturing time and cost increase
Solution Approach 1:
The patent merges the encapsulation and adhesion functions into a single integrated material layer, eliminating the need for separate pre-compounding and adhesion steps. The encapsulating material is designed to provide both mechanical encapsulation and sufficient adhesion in one component, allowing for a simplified one-step manufacturing process that reduces both time and cost while maintaining heat resistance through the material's inherent properties and controlled cross-linking.
Solution Approach 2:
The patent incorporates heat resistance properties directly into the base material composition through the selection of thermally stable polymers and inorganic fillers, rather than relying on post-application heat treatment processes. This preliminary incorporation of heat resistance into the material design eliminates the need for subsequent high-temperature adhesion steps, thereby reducing manufacturing time and process complexity.
4Strength
If cross-linked encapsulating material is used to improve adhesiveness, then adhesiveness is improved, but silicon cell reuse becomes impossible
Solution Approach 1:
The patent carefully controls the cross-linking parameter by using specific cross-linking agents in limited quantities and by optimizing the vinyl acetate content to achieve moderate cross-linking density. This controlled parameter adjustment provides sufficient adhesiveness for normal operation while maintaining the possibility of future separation, as the cross-links are not overly strong or extensive.
Solution Approach 2:
The patent extracts or removes the silane coupling agent that would create permanent, strong bonds between the encapsulating material and metal sections. By eliminating this component, the material maintains adequate adhesiveness through other mechanisms (van der Waals forces, mechanical interlocking) while preventing the formation of irreversible chemical bonds that would make silicon cell reuse impossible.
Data Source
AI summary
An encapsulating material for solar cell containing a laminated adhesive and heat resistant layer (A) and a buffering layer (B), wherein a difference in flexural modulus between the heat resistant layer (A) and the buffering layer (B) is at least 30 MPa or more, is provided. The adhesive and heat resistant layer (A) is preferably an olefin polymer (a) having a melting point (according to JIS K7121) of 75° C. or higher and having a storage elastic modulus at 150° C. of 103 Pa or more and the buffering layer (B) is preferably an olefin polymer (d) having a stiffness of 100 MPa or less. The encapsulating material for solar cell can provide superior transparency, flexibility, heat resistance and adhesiveness and can remarkably improve production efficiency of a solar cell module even when no organic peroxide is used. The encapsulating material can also exhibit a performance capable of corresponding to the thickness reduction of the solar cell element even when an organic peroxide is used. A solar cell module containing the encapsulating material is also provided.