UV Curable Encapsulant for Photovoltaic Cells
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Solution Overview
Problem
Current encapsulant compositions for photovoltaic cells, such as EVA, face issues with adhesion to protective layers, durability under solar radiation, and compatibility with transparent plastics like PMMA, leading to corrosion and reduced module efficiency.
Innovation Solution
A UV-curable liquid encapsulant composition based on acrylic or methacrylic block copolymers, combined with acrylic or methacrylic monomers and photoinitiators, offering improved adhesion to plastics and ceramics, and resistance to UV radiation and heat, with a glass transition temperature below 0°C to minimize stress and maintain transparency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If EVA-based encapsulant is used, then transparency is good, but adhesion to protective layers is insufficient and requires coupling agents
Solution Approach 1:
The invention changes the chemical composition parameters by using acrylic and/or methacrylic copolymers with specific Tg ranges (-50°C to 0°C) instead of EVA, achieving both good transparency and inherent adhesion to protective layers without requiring additional coupling agents
Solution Approach 2:
The invention uses composite encapsulant formulations combining acrylic/methacrylic copolymers with specific monomers (acrylates, methacrylates) and photoinitiators to achieve synergistic effects that provide both transparency and strong adhesion properties
2Ease of manufacture
If EVA-based encapsulant is used, then manufacturing is simple, but durability under solar radiation is poor leading to yellowing and corrosion
Solution Approach 1:
The invention changes the chemical structure parameters by selecting acrylic/methacrylic copolymers with low Tg values and specific compositional ratios that inherently resist UV degradation and yellowing, while maintaining ease of processing through photopolymerization
Solution Approach 2:
The invention uses photoinitiators that enable complete curing of the encapsulant material under UV light, creating a durable, long-lasting protective layer that prevents the degradation issues seen in EVA materials
3Stress or pressure
If encapsulant modulus of elasticity is reduced for thin PV cells, then stress at low temperatures is reduced, but adhesion strength may be compromised
Solution Approach 1:
The invention changes the viscoelastic parameters by using acrylic/methacrylic copolymers with specifically controlled Tg values (-50°C to 0°C) that provide low modulus of elasticity for stress relief while the chemical composition ensures strong adhesion through molecular interactions with protective layers
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 encapsulant composition provides excellent transparency, adhesion, and durability, maintaining performance over a broad temperature range and resisting aging, making it suitable for photovoltaic cells and modules, especially for CPV applications, with improved resistance to water, oxygen, and thermal stress.
Implementation Method 1
UV curable encapsulant compositions based on acrylic and/or methacrylic block copolymers
Implementation Method 2
the encapsulant must offer optimal and durable transparency to the solar radiation
Data Source
Figure 1
AI summary
The present invention relates to UV curable encapsulant compositions based on acrylic and/or methacrylic block copolymers, to structures containing these compositions especially photovoltaic cells and to the use of these compositions in photovoltaic cells. The liquid encapsulant composition according to the invention comprises: an acrylic or methacrylic block copolymer, at least one acrylic or methacrylic monomer and/or oligomer, and at least one photo initiator. wherein said acrylic or methacrylic block copolymer is of the general formula B- (A)n, wherein: n is a natural integer greater than or equal to 1, B represents an acrylic or methacrylic polymer block composed of a sequence of monomer units which may be polymerized by the radical route, the overall Tg of which is less than 0°C, A is an acrylic or methacrylic polymer block composed of a sequence of monomer units which may be polymerized by the radical route, the overall Tg of which is greater than 0°C, block B represents at least 50%, and preferably from 60% to 95% w/w of the block copolymer.