Polymeric Backsheet for Bifacial PV Modules
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Solution Overview
Problem
Bifacial photovoltaic modules face challenges with high PID degradation, mechanical stability, and cost issues due to glass-glass designs, and existing polymeric transparent backsheets have limitations in interlayer adhesion, hydrolytic stability, and environmental concerns.
Innovation Solution
A layer element comprising a polyethylene-based layer with silane-containing units and a polypropylene-based layer, providing high total transparency and improved mechanical and thermal stability, is used as an integrated backsheet in bifacial photovoltaic modules, enhancing power output from the rear side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If glass-glass design is used for bifacial PV modules, then transparency and power output from rear side are improved, but weight increases and handling becomes difficult
Solution Approach 1:
The patent changes the material parameter from glass to polymeric materials (specifically polyethylene and polypropylene layers), maintaining optical transparency while significantly reducing weight. The polymeric backsheet achieves comparable transparency to glass but with much lower density, directly resolving the weight-transparency contradiction.
Solution Approach 2:
The patent employs polymeric materials that are cheaper and lighter than glass, sacrificing some perceived durability for significant gains in weight reduction and cost. The polymeric backsheet provides sufficient service life for PV applications while being much easier to handle and install.
2Illumination intensity
If glass-glass design is used for bifacial PV modules, then transparency is improved, but mechanical stability and PID resistance deteriorate
Solution Approach 1:
The patent uses a composite structure with multiple polymeric layers (polyethylene layer with silane groups, polypropylene layer) that work together to provide both transparency and mechanical stability. The composite polymeric structure mimics the protective functions of glass while adding flexibility and PID resistance through material selection.
Solution Approach 2:
The polymeric backsheet acts as an intermediary material between the PV cells and the external environment, providing protection against PID degradation while maintaining optical transparency. The polymeric material mediates between the electrical sensitivity of the cells and environmental exposure, preventing ion migration issues associated with glass.
3Weight of moving object
If conventional polymeric transparent backsheet is used, then weight is reduced, but interlayer adhesion and hydrolytic stability deteriorate
Solution Approach 1:
The patent modifies the chemical parameters of the polyethylene layer by incorporating silane groups, which fundamentally change the adhesion properties. This chemical modification enables strong interlayer bonding and hydrolytic stability while maintaining the weight advantages of polymeric materials over glass.
Solution Approach 2:
The patent applies different functional properties to different layers: the polyethylene layer provides adhesion through silane groups, the polypropylene layer provides transparency and mechanical properties. Each layer is optimized for its specific function, creating a composite structure that overcomes the limitations of single-material solutions.
4Weight of moving object
If conventional polymeric transparent backsheet is used, then weight is reduced, but environmental concerns increase
Solution Approach 1:
The patent changes the chemical composition parameters by using silane-modified polyethylene and specific polypropylene formulations that are more environmentally stable and resistant to degradation. These material parameter changes reduce environmental concerns while maintaining the lightweight advantage.
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 layer element achieves high transparency and mechanical stability, increasing power output from the rear side of bifacial photovoltaic modules while addressing PID degradation and cost concerns associated with glass-glass designs.
Implementation Method 1
Layer (A) comprises a polyethylene composition (PE-A) comprising (PE-A-a) a copolymer of ethylene, which bears silane group(s) containing units
Data Source
AI summary
The invention relates to a layer element comprising at least two layers (A) and (B), wherein layer (B) has a has a total luminous transmittance of at least 80.0%, an article, preferably abifacial photovoltaic module, comprising said layer element, a process for preparing said layer element, a process for preparing a photovoltaic module comprising said layer element and the use of said layer element as integrated backsheet element of a bifacial photovoltaic module.