Solar Cell Sheet Edge Thickening to Reduce Warpage and Micro-Cracks
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Solution Overview
Problem
Existing solar cell manufacturing processes face issues with stress-related defects such as warpage, micro-cracks, and fragmentation due to mismatched thermal expansion coefficients and etching processes, which compromise the structural integrity and reliability of the solar cell sheet.
Innovation Solution
A solar cell sheet design with a thicker edge portion relative to the middle portion, combined with selective laser and wet etching techniques, to optimize stress distribution and enhance structural strength, reducing the risk of warping and impact damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If uniform thickness etching is applied across the entire silicon wafer, then the polysilicon layer is effectively removed from the non-grid-line region, but the edge portion becomes too thin and prone to warpage and micro-cracks
Solution Approach 1:
The patent applies different etching depths to different regions of the silicon wafer: the middle portion undergoes deeper etching to completely remove the polysilicon layer, while the edge portion undergoes shallower etching to preserve structural strength. This local differentiation resolves the contradiction by allowing precise polysilicon removal where needed while maintaining edge integrity.
Solution Approach 2:
The silicon wafer is segmented into two distinct regions for etching purposes: the middle portion and the edge portion. Each region receives a tailored etching depth (first etching depth for middle, second etching depth for edge), enabling simultaneous achievement of complete polysilicon removal and structural strength preservation.
2Manufacturing precision
If the entire non-grid-line region is etched by 2-3 μm, then the polysilicon layer is removed, but the thin cell sheet becomes vulnerable to warpage and fragmentation during high-temperature processing
Solution Approach 1:
The patent implements location-specific etching depths where the middle portion is etched deeper (first etching depth) to ensure complete polysilicon removal, while the edge portion is etched shallower (second etching depth) to maintain structural integrity during subsequent high-temperature processes, thus resolving the contradiction between removal uniformity and processing reliability.
3Manufacturing precision
If deep etching is applied to remove all polysilicon, then the non-grid-line region is clean, but the edge portion suffers from reduced thickness and increased susceptibility to impact damage
Solution Approach 1:
The patent applies differentiated etching depths: the middle portion receives deeper etching to achieve complete polysilicon removal, while the edge portion receives shallower etching to preserve thickness and impact resistance. This local quality approach resolves the contradiction between removal completeness and impact resistance.
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 enhanced structural strength improves product yield, reliability, and service life of the solar cell sheet by minimizing warpage, micro-cracks, and edge damage, facilitating better processing and assembly into photovoltaic modules.
Implementation Method 1
irradiating the doped polysilicon layer in the non-grid-line region with a laser; and removing the doped polysilicon layer and the portion of the silicon wafer in the non-grid-line region by a wet etching process
Implementation Method 2
removing the doped polysilicon layer and the portion of the silicon wafer in the non-grid-line region by a wet etching process
Data Source
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AI summary
The present invention provides a solar cell sheet and a preparation method therefor and a photovoltaic module, relating to the technical field of photovoltaics. The solar cell sheet comprises a silicon wafer, a doped polysilicon layer, and grid lines, and a thickness of the silicon wafer at a non-grid-line region in an edge portion of the silicon wafer is greater than a thickness of the silicon wafer at a non-grid-line region in a middle portion. In embodiments of the present invention, since the non-grid-line region of the edge portion has a greater thickness relative to the non-grid-line region of the middle portion, structural strength thereof is better than that of the middle portion. This makes the silicon wafer and the solar cell sheet not prone to warping, micro-cracking, or fragmenting, and not prone to being damaged due to impact. In processing of the solar cell sheet, in assembly of a photovoltaic module, and in subsequent use of the photovoltaic module, a silicon wafer having better reliability can enable the solar cell to have a higher product yield, better performance, and a longer service life.