Polyvinyl Acetal Encapsulation for Photovoltaic Cells
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Solution Overview
Problem
The existing encapsulation materials for photovoltaic solar cell modules, such as EVA, degrade under intense sunlight and heat, leading to a significant loss in power output over time, necessitating the development of a more stable and efficient encapsulation method.
Innovation Solution
A method using a polyvinyl acetal resin combined with ethylenically unsaturated monomers or oligomers, cured in the presence of thermal free radical initiators or photoinitiators, which can be processed at ambient pressure and temperature, offering improved cure speed and stability compared to traditional EVA encapsulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If EVA is used as encapsulant, then processability and low cost are achieved, but progressive darkening occurs under intense sunlight leading to greater than 30% loss in power output after four or more years
Solution Approach 1:
The patent changes the chemical composition parameters of the encapsulant material from conventional EVA to a fluorinated polymer composition containing fluorocarbon groups. This parameter change fundamentally alters the material's resistance to UV degradation and yellowing while maintaining ease of processing through established lamination techniques.
Solution Approach 2:
The invention uses a composite polymer system combining fluorinated vinylidene copolymer with other fluorinated polymer components. This composite material structure provides synergistic effects that enhance both the optical stability and electrical performance while maintaining manufacturability through conventional processes.
2Ease of manufacture
If EVA is used as encapsulant, then commercial acceptance and cost effectiveness are achieved, but discoloration results from chemical degradation under ultraviolet light
Solution Approach 1:
The patent modifies the chemical structure by incorporating fluorinated groups into the polymer backbone, which fundamentally changes the material's interaction with ultraviolet radiation. The fluorinated bonds have higher energy requirements for breaking, providing inherent UV resistance while maintaining compatibility with commercial lamination processes.
Solution Approach 2:
The invention replaces the short-lived conventional EVA material with a long-lasting fluorinated polymer that maintains its optical and electrical properties over extended periods. This substitution eliminates the need for premature module replacement due to encapsulant degradation.
3Power
If conventional encapsulation materials are used, then initial power output is achieved, but significant power loss occurs over time due to degradation
Solution Approach 1:
The patent changes the encapsulant material composition to fluorinated polymers that maintain high light transmittance and electrical insulation properties over time. This parameter change ensures that the module's power output is preserved throughout the extended service life without significant degradation.
Solution Approach 2:
The invention provides encapsulation properties that exceed the minimum requirements for initial power output by incorporating materials with superior long-term stability. The fluorinated polymer system delivers more than adequate electrical insulation and optical clarity, ensuring sustained high performance well beyond typical module lifetimes.
4Reliability
If polyvinyl acetal resin with ethylenically unsaturated monomers is used, then improved durability and light transmittance are achieved, but additional processing steps are required
Solution Approach 1:
The patent modifies the resin composition by incorporating ethylenically unsaturated monomers into the polyvinyl acetal structure, enabling crosslinking that enhances durability. The formulation is designed to cure under standard lamination conditions, adding minimal complexity to the manufacturing process while delivering superior long-term performance.
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 new encapsulation method provides enhanced durability and light transmittance, with minimal shrinkage and haze, maintaining high power output over extended periods while being recyclable and environmentally friendly.
Implementation Method 1
curing a composition comprising a polyvinyl acetal resin and one or more ethylenically unsaturated monomers, oligomers, or a combination thereof, in the presence of a photoinitiator
Implementation Method 2
curing a composition comprising a polyvinyl acetal resin and one or more ethylenically unsaturated monomers, oligomers, or a combination thereof, in the presence of a thermal free radical initiator
Data Source
AI summary
The invention relates to a method of encapsulating a photovoltaic cell comprising curing an encapsulation composition comprising (i) a polyvinyl acetal resin/polymer, (ii) one or more ethylenically unsaturated monomers, oligomers, or a combination thereof, and (iii) at least one thermal free radical initiator and/or at least one photoinitiator. The resin/polymer is either a polyvinyl acetate derivative or a polyvinyl acetate copolymer such as EVA derivative, and comprises vinyl acetal units. The invention also relates to a photovoltaic cell encapsulated according to the method and to the encapsulation curable composition.