Solar Cell Electrode Layout for Warpage and Finger Disconnection
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Solution Overview
Problem
Solar cells face issues with warpage and reduced adhesive strength of finger electrodes, leading to electrical conduction failures and decreased conversion efficiency due to material expansion differences and inadequate adhesive strength, which affects long-term reliability and high output.
Innovation Solution
The introduction of auxiliary electrodes that connect adjacent finger electrodes to bus bar electrodes, reducing line resistance and enhancing adhesive strength, while maintaining a minimal light-receiving area, thereby improving fill factor and conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If finger electrodes are shortened to reduce warpage, then warpage is reduced, but adhesive strength decreases and disconnection occurs
Solution Approach 1:
An auxiliary electrode layer is introduced as an intermediary between the finger electrode and the bus bar electrode. This auxiliary electrode serves as a mediator that enhances adhesive strength and provides alternative current pathways, resolving the contradiction between reducing warpage by shortening electrodes and maintaining reliable electrical connection.
Solution Approach 2:
The invention changes the structural parameters of the electrode system by adding an auxiliary electrode layer with specific thickness (5-50 μm) and conductivity properties. This parameter change allows the finger electrode to be shorter while maintaining overall adhesive strength and electrical connectivity through the auxiliary layer.
2Area of stationary object
If line width of finger electrodes is reduced to minimize substrate area, then light-receiving area increases, but skipping and breakage occur
Solution Approach 1:
The electrical conduction path is segmented into multiple pathways by introducing the auxiliary electrode layer. This segmentation allows current to flow through multiple routes (direct path through finger electrode or alternative path through auxiliary electrode), preventing complete failure even if the narrow finger electrode breaks or skips.
Solution Approach 2:
The auxiliary electrode layer acts as a pre-established backup pathway that cushions against potential failures of the narrow finger electrode. By providing alternative current paths in advance, it prevents electrical conduction failures even when the thin finger electrodes experience breaking or skipping during manufacturing or operation.
3Ease of manufacture
If conductive paste is printed and sintered to form electrodes, then electrode formation is achieved, but warpage occurs due to expansion coefficient difference
Solution Approach 1:
The invention uses a composite electrode structure consisting of multiple layers (finger electrode, auxiliary electrode, bus bar electrode) with different material properties. The auxiliary electrode layer acts as a buffer zone that compensates for the thermal expansion coefficient difference between the silicon substrate and the aluminum electrode, reducing warpage while maintaining ease of manufacture through screen printing.
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 effectively mitigates warpage, increases adhesive strength, and maintains high conversion efficiency and output retention, even under thermal stress, by ensuring continuous current flow and reducing peeling failures, thus enhancing the solar cell's long-term reliability and manufacturing yield.
Implementation Method 1
auxiliary electrodes that connect adjacent finger electrodes to bus bar electrodes, reducing line resistance
Implementation Method 2
a solar cell which has long-term reliability and high conversion efficiency
Data Source
Figure 1~3
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Figure 7~8
AI summary
Provided is a solar cell that includes: a semiconductor substrate on which at least pn junctions are formed; a multiplicity of finger electrodes that are formed in a comb-like shape on at least one surface of the semiconductor substrate; and a plurality of bus bar electrodes that are arranged so as to be orthogonal to the lengthwise direction of the finger electrodes and are connected with the finger electrodes. This solar cell is configured so that the finger electrodes connected with one of the bus bar electrodes are separated from the finger electrodes connected with another bus bar electrode that is arranged so as to be parallel to this one of the bus bar electrodes, and ends in the lengthwise direction of adjacent two or more of the finger electrodes connected with each bus bar electrode are electrically connected with one another by auxiliary electrodes. With this configuration, while disadvantage due to disconnection is solved, a high fill factor, a high conversion efficiency, and small cell warpage are achieved, whereby the manufacturing yield is improved. Further, this does not involve increases in costs, and high long-term reliability is achieved. Thus, a solar cell module made up of the solar cells maintains high output.