Solar Cell Electrode Overlap Structure for Better Paste Contact
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Solution Overview
Problem
The existing solar cell manufacturing process results in poor contact between firing-through and non-firing-through pastes due to limitations in printing accuracy and adhesion characteristics, leading to reduced open-circuit voltage and conversion efficiency.
Innovation Solution
A solar cell design featuring a silicon substrate with a passivation layer, a first electrode conductor with protruding portions, and a second electrode conductor that overlap to form a local metallized structure, where the first electrode conductor penetrates the passivation layer and contacts the substrate, while the second electrode conductor is isolated, optimizing contact area and reducing recombination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If firing-through paste and non-firing-through paste are printed on the silicon substrate surface, then local-contact metallized structure is formed to conduct electricity, but poor contact between pastes reduces open-circuit voltage and conversion efficiency
Solution Approach 1:
The invention transitions from a planar contact structure to a three-dimensional structure by adding protruding portions that extend vertically from the passivation layer. This dimensional change allows the first electrode conductor to make contact with the second electrode conductor at multiple levels, compensating for printing accuracy limitations and ensuring reliable electrical connection despite variations in paste placement precision.
Solution Approach 2:
The protruding portions are pre-formed on the first electrode conductor before the final assembly, anticipating potential misalignment issues. This preliminary structural preparation ensures that even if the printing process has accuracy limitations, the protruding portions will extend far enough to guarantee contact with the second electrode conductor, thereby maintaining reliable electrical connection.
2Ease of manufacture
If printing process is used to apply pastes, then electrode conductors are formed on passivation layer, but adhesion characteristics and screen printing limitations cause poor contact
Solution Approach 1:
The invention changes the geometric parameters of the first electrode conductor by adding protruding portions with specific dimensions (width of 5-20 μm, length extending beyond the body portion). This parameter modification ensures that even with variations in printing adhesion and screen printing characteristics, the protruding portions maintain sufficient contact area with the second electrode conductor, guaranteeing reliable electrical connection.
Solution Approach 2:
The first electrode conductor is segmented into a body portion and protruding portions, with each serving distinct functions. The body portion provides the main conductive path, while the protruding portions specifically engage with the second electrode conductor. This segmentation allows the structure to compensate for printing process limitations while maintaining ease of manufacture through standard screen printing techniques.
3Reliability
If protruding portions are added to increase contact area, then open-circuit voltage improves, but overlapping area must be controlled to optimize performance
Solution Approach 1:
The invention optimizes the overlapping area between the first and second electrode conductors by controlling it to be 5%-25% of the total area of the first electrode conductor. This parameter optimization ensures sufficient contact for reliable electrical connection while minimizing unnecessary complexity in the electrode structure, achieving the right balance between contact quality and structural simplicity.
Data Source
AI summary
Provided are a solar cell and a photovoltaic module. The solar cell includes: a silicon substrate; a passivation layer provided on a surface of the silicon substrate; a first electrode conductor at least partially arranged on the passivation layer and including a body portion and protruding portions located on two ends of the body portion; and a second electrode conductor at least partially arranged on the passivation layer and at least partially overlapping with the protruding portions. A length of each of the protruding portions in a width direction of the body portion is greater than a width of the body portion.