Solar Cell Screen Printing Plate Segmented Bus Bar Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing screen printing methods for solar cells often result in breakage at the connection between bus bar electrodes and finger electrodes due to differences in film thickness and shrinkage, leading to reduced conversion efficiency and aesthetic issues.
Innovation Solution
A screen printing plate with a bus bar electrode opening that includes blocked zones to reduce pressure and prevent breakage, allowing for the formation of high-aspect-ratio electrodes without increasing shadow loss or compromising appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the finger electrode is made thin with high aspect ratio to reduce electrode area, then light-receiving surface efficiency is improved, but the connection between bus bar electrode and finger electrode becomes very thin and may break during firing
Solution Approach 1:
The bus bar electrode opening is divided into multiple segments by introducing blocked zones, creating a multi-section structure. This segmentation allows different regions to serve different functions: some regions permit paste flow for electrode formation while blocked zones prevent excessive paste accumulation and reduce shrinkage stress at critical connection points, thereby preventing breakage of thin finger electrodes during firing
Solution Approach 2:
Different regions of the bus bar electrode opening are given different properties through blocked zones. The blocked zones create local variations in paste distribution, allowing the connection regions to have reduced paste thickness and lower shrinkage stress, while other regions maintain adequate electrode formation. This local differentiation ensures the reliability of thin finger electrode connections without compromising overall electrode functionality
2Ease of manufacture
If conventional screen printing is used to form electrodes, then manufacturing process is simple and low cost, but breakage occurs at the connection between bus bar electrode and finger electrode due to film thickness differences and shrinkage
Solution Approach 1:
The bus bar electrode opening is segmented into multiple sections by blocked zones, creating a controlled paste distribution pattern. This segmentation modifies the conventional screen printing process to prevent excessive paste accumulation at finger electrode connections, reducing shrinkage stress and preventing breakage during firing while maintaining the simplicity and low cost of screen printing manufacturing
Solution Approach 2:
Blocked zones act as intermediary elements within the bus bar electrode opening, mediating the paste flow and distribution. These blocked zones control where paste can accumulate and where it must be restricted, serving as intermediaries that prevent direct excessive paste buildup at vulnerable connection points, thereby preventing breakage while maintaining conventional screen printing process
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 effectively prevents breakage at the connection between bus bar and finger electrodes, enhancing the manufacturing of solar cells with high conversion efficiency and productivity while maintaining a clean aesthetic appearance.
Implementation Method 1
The screen printing process uses a screen printing plate which is prepared by providing a mesh fabric 110 of orthogonally woven warp and weft filaments, coating the fabric with a photosensitive emulsion 111, exposure, and removing parts of the emulsion to define a substantially rectangular pattern hole
Implementation Method 2
A flexible blade known as printing squeegee 112 is traversed at a suitable squeegee hardness (60 to 80 degrees), squeegee angle (60 to 80 degrees), pressure or applied pressure (0.2 to 0.5 MPa), and printing speed (20 to 100 mm/s) for thereby transferring the print paste to the work to be printed
Implementation Method 3
A solar cell manufactured by the prior art technology is described with reference to its cross-sectional view (FIG. 1), front surface configuration (FIG. 2), and back surface configuration (FIG. 3). In general, the solar cell includes a p-type semiconductor substrate 100 of silicon or the like in which an n-type dopant is diffused to form an n-type diffusion layer 101 to define a p-n junction
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
The present invention relates to screen printing plate for a solar cell in which an electroconductive paste is used to simultaneously print a bus bar electrode and a finger electrode, the screen printing plate characterized in that the opening width of a finger electrode opening of the screen printing plate is less than 80 µm and a bus bar electrode opening of the screen printing plate has a closed section. The use of this screen printing plate makes it possible to reduce the cost of manufacturing solar cells, prevent the connecting section between the bus bar electrode and the finger electrode from breaking without causing an increase in shadow loss or compromising the aesthetic quality of the solar cells, and manufacture highly reliable solar cells with good productivity.