Solar Encapsulant Polyolefin Composition for Fast Curing Resistivity
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Solution Overview
Problem
Current polymeric encapsulants for photovoltaic modules, such as EVA and POE, face issues with low volume resistivity, moisture barrier properties, and premature crosslinking, leading to degradation and reduced power output, while attempting to balance properties like crosslinking rate and volume resistivity remains a challenge.
Innovation Solution
A polyolefin composition comprising ≥60.0 wt. % ethylene alpha-olefin co-polymer with specific melting temperature and vinyl unsaturation, ≥1.0 wt. % ethylene-alpha-olefin-diene terpolymer, and ≥0.1 wt. % crosslinking agent, optimized for high volume resistivity and short curing time, is developed, incorporating a crosslinking agent and silane coupling agents to enhance processability and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If crosslinking is performed to increase thermal creep resistance and shorten curing time, then thermal creep resistance improves, but material corrosion occurs due to residual peroxides and premature crosslinking happens
Solution Approach 1:
The patent introduces a silane coupling agent as an intermediary substance between the polyolefin and crosslinking agent. The silane coupling agent has both organophilic groups that interact with polyolefin and inorganic hydrolyzable groups that react with moisture to form crosslinks, thereby mediating the crosslinking process to avoid direct contact between peroxides and sensitive materials, reducing corrosion while maintaining thermal creep resistance
Solution Approach 2:
The patent changes the crosslinking mechanism from direct peroxide-initiated crosslinking to a two-stage process: first silane grafting onto polyolefin chains, then hydrolysis and condensation of silane groups to form crosslinks. This parameter change in the crosslinking pathway allows controlled crosslinking without the harmful effects of residual peroxides, achieving both thermal creep resistance and material stability
2Ease of manufacture
If EVA copolymer is used to improve processability, then ease of manufacture improves, but volume resistivity decreases and moisture barrier properties worsen
Solution Approach 1:
The patent creates a composite material system combining polyolefin (for high volume resistivity and moisture barrier), silane coupling agent (for crosslinking capability), and crosslinking agent (for thermal creep resistance). This composite approach allows each component to contribute its strengths: polyolefin provides electrical and moisture resistance, while the silane-crosslinking system provides processability and thermal stability without compromising the inherent advantages of polyolefin
3Reliability
If polyolefin elastomer is used to maintain high volume resistivity, then volume resistivity improves, but crosslinking rate decreases
Solution Approach 1:
The silane coupling agent serves as an intermediary that enables crosslinking in polyolefin without requiring high-energy peroxide initiation. The silane groups graft onto polyolefin chains during processing, then hydrolyze and condense at lower temperatures to form crosslinks, thereby achieving fast crosslinking rates while preserving the high volume resistivity characteristic of polyolefin
Solution Approach 2:
The patent replaces the traditional peroxide-based chemical crosslinking mechanism with a silane-based crosslinking mechanism. This substitution changes the crosslinking chemistry from radical-based (peroxide) to condensation-based (silane hydrolysis), enabling faster crosslinking rates at lower temperatures while maintaining the electrical properties of polyolefin
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 polyolefin composition achieves high volume resistivity, improved processability, and reduced curing time, effectively addressing the limitations of existing encapsulants by maintaining thermal stability and preventing degradation, making it suitable for photovoltaic module encapsulants.
Implementation Method 1
A possible way of increasing thermal creep resistance, is by subjecting the polymeric material to conditions of crosslinking in presence of organic peroxide initiators
Implementation Method 2
incorporating a crosslinking agent and silane coupling agents to enhance processability and thermal stability
Data Source
AI summary
A crosslinkable polyolefin composition includes: a) ≥60.0 wt. % and ≤99.0 wt. % of an ethylene alpha-olefin co-polymer; b) ≥1.0 wt. % and ≤35.0 wt. % of an ethylene-alpha-olefin-diene terpolymer; c) ≥0.1 wt. % and ≤5.0 wt. % of a crosslinking agent; with regard to the total weight of the polyolefin composition. A film includes the polyolefin composition. An encapsulated solar cell is encapsulated by at least two sealing layers each including such a film. In addition, a cured solar cell is obtained by subjecting the encapsulated solar cell under conditions of curing the sealing layers, a photovoltaic module includes the cured solar cell.