Polyolefin Encapsulant and PVDF Back Sheet for Moisture Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Photovoltaic modules using EVA-based encapsulants are vulnerable to moisture, leading to delamination, yellowing, and electrode corrosion, which reduces their lifespan and efficiency, especially in humid environments, and generates acidic wastewater causing environmental pollution.
Innovation Solution
A photovoltaic module with a polyolefin-based encapsulant, specifically low-density polyethylene (LDPE), and a back sheet structure of sequentially laminated polyethylene (PE), polyethyleneterephthalate (PET), and polyvinylidene fluoride (PVDF) layers, enhancing bonding force and moisture resistance, and coated with UV absorbents to prevent yellowing and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If EVA-based encapsulant is used, then bonding force between solar cells and materials is strong, but moisture resistance is poor leading to delamination and yellowing
Solution Approach 1:
The patent changes the chemical composition parameter of the encapsulant from EVA to polyolefin (specifically LDPE), which fundamentally alters the material's interaction with moisture. This parameter change maintains bonding capability while eliminating the chemical reaction with moisture that causes yellowing and delamination in EVA-based systems.
Solution Approach 2:
The patent employs a composite back sheet structure consisting of multiple layers (PVF, PET, PVF) to achieve both moisture barrier properties and bonding compatibility with polyolefin encapsulant. This composite approach allows the system to overcome the limitations of single-material solutions.
2Illumination intensity
If EVA film is used as encapsulant, then light transmission is enhanced, but acetic acid generation causes yellowing and electrode corrosion
Solution Approach 1:
The patent eliminates the harmful chemical reaction pathway by replacing EVA with polyolefin encapsulant. The polyolefin material does not undergo hydrolysis to produce acetic acid, thereby converting a chemically reactive system into a chemically stable one while maintaining optical performance.
3Reliability
If polyolefin encapsulant is used, then moisture resistance is improved, but bonding force with conventional back sheet is reduced
Solution Approach 1:
The patent modifies the back sheet material composition parameter by selecting PVF (polyvinyl fluoride) and PET (polyethyleneterephthalate) layers that are chemically compatible with polyolefin encapsulant. This parameter change ensures adequate bonding force while maintaining the moisture resistance benefits of the polyolefin material.
4Reliability
If PVF-PET-PVF back sheet structure is used with polyolefin encapsulant, then moisture resistance is achieved, but surface roughness increases
Solution Approach 1:
The patent applies different material properties to different layers of the back sheet. The PVF layers provide moisture barrier and chemical compatibility, while the PET layer provides structural stability and surface smoothness. This local differentiation of material functions resolves the contradiction between moisture resistance and surface quality.
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 solution significantly increases moisture resistance and structural stability, prevents yellowing and electrode corrosion, and reduces lamination time, allowing the module to maintain high efficiency in humid conditions and minimize environmental impact.
Implementation Method 1
coated with UV absorbents to prevent yellowing and corrosion
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A photovoltaic module according to the present disclosure includes at least one solar cell, an encapsulant laminated to encapsulate upper and lower surfaces of the at least one solar cell, a transparent insulating substrate laminated on an upper surface of the encapsulant, and a back sheet laminated on a lower surface of the encapsulant, wherein the encapsulant is formed of a polyolefin-based material, and the back sheet is formed by sequentially laminating polyethylene (PE) layer, polyehthyleneterephthalate (PET) layer, and polyvinylidene fluoride (PVDF) layer, starting from the lower surface of the encapsulant, whereby yellowing and corrosion due to moisture permeation can be prevented and a melting time for bonding materials of the laminated module can be reduced, which may result in enhancing productivity, improving a bonding force of the back sheet with respect to the polyolefin-based encapsulant, and preventing surface roughness, thereby enhancing structural stability of the photovoltaic module.