Low MFR Silane EVA Encapsulant for PV Module Lamination
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Solution Overview
Problem
The production of rigid photovoltaic (PV) modules faces challenges due to the high melt flow rate (MFR) of conventional ethylene vinyl acetate (EVA) encapsulant materials, leading to material flow-out and stress on fragile solar cells during lamination, which increases production costs and complexity.
Innovation Solution
A polymer composition for PV modules comprising ethylene with polar comonomers and silane groups, having a melt flow rate of less than 20 g/10 min, is used without silanol condensation catalysts, allowing for reduced flow and improved shear thinning behavior, enabling better handling and integrity of glass layers during lamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional EVA with high VA content is used as encapsulant material, then flowability and processability are improved, but substantial flow-out and shifting of solar cells occur during lamination
Solution Approach 1:
The patent changes the chemical composition parameters of the encapsulant by replacing vinyl acetate comonomers with polar comonomers (acrylates, methacrylates) and incorporating silane groups. This parameter change reduces MFR from >15 g/10min to <10 g/10min, thereby reducing flow-out while maintaining adequate flowability for lamination processability.
Solution Approach 2:
The patent creates a composite polymer system combining ethylene backbone with polar comonomer units and silane functional groups. This composite structure integrates the benefits of reduced flow-out (from lower MFR) with maintained processability (from polar groups) and potential crosslinking capability (from silane groups), resolving the contradiction between flow control and manufacturability.
2Reliability
If high MFR encapsulant material is used, then surface wetting and stress reduction on solar cells are improved, but material flow-out increases
Solution Approach 1:
The patent optimizes the MFR parameter to a specific range (<10 g/10min) through compositional changes, balancing surface wetting capability with flow-out prevention. The polar comonomers maintain wetting properties while the overall lower MFR prevents excessive flow.
Solution Approach 2:
The patent introduces polar comonomer units at specific locations within the polymer chain structure. These localized polar groups provide surface wetting and adhesion properties without requiring high overall MFR, thus preventing flow-out while maintaining local wetting quality at the encapsulant-solar cell interface.
3Object-generated harmful factors
If peroxide crosslinking is applied during lamination, then flow-out is prevented, but lamination cycle time and production complexity increase
Solution Approach 1:
The patent extracts the crosslinking function from the lamination process by incorporating pre-reacted silane groups into the encapsulant polymer structure. The crosslinking capability is built into the material itself rather than being applied as a separate process step, thereby preventing flow-out without adding process complexity.
Solution Approach 2:
The silane groups are pre-incorporated into the polymer chain during encapsulant manufacturing, before lamination. This preliminary preparation enables the material to self-crosslink or self-stabilize during lamination without requiring external peroxide addition or extended crosslinking cycles, thus preventing flow-out while simplifying the lamination process.
4Object-generated harmful factors
If low MFR polymer is used, then flow-out is reduced, but film extrusion processability deteriorates
Solution Approach 1:
The patent changes the chemical structure parameters by introducing polar comonomer units that enhance processability through improved melt rheology and adhesion, allowing low MFR materials to be successfully extruded into films. The polar groups facilitate better polymer-chain interactions that improve extrusion behavior despite low MFR.
Solution Approach 2:
The patent creates a composite polymer structure where the ethylene backbone provides low MFR (flow-out prevention) while polar comonomer units and silane groups provide processability. This composite material combines properties that individually would be contradictory, achieving both low flow-out and good extrusion 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
This solution minimizes material flow-out, reduces mechanical stress on solar cells, and allows for optimal film extrusion conditions, resulting in higher-quality PV modules with improved mechanical integrity and reduced production time.
Implementation Method 1
improved shear thinning behavior, enabling better handling and integrity of glass layers during lamination
Data Source
Figure 1
AI summary
The present invention relates to a photovoltaic (PV) module and to a lamination process for producing said PV module.