Back-Contact Cell String Layout to Prevent Bonding Material Leakage
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Solution Overview
Problem
The material of the bonding layer easily overflows into the gap between positive and negative electrode fingers in busbar-free back contact solar cells, causing electric leakage in the photovoltaic module.
Innovation Solution
A solar cell string design with first and second doped layers alternately arranged along different directions, featuring first connecting members connected to first fingers and second insulating blocks that extend into isolation regions, preventing short-circuits and ensuring reliable connections by blocking the first connecting members from the second fingers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bonding layer is used to connect the soldering strip to the positive electrode fingers, then the connection reliability is improved, but the bonding material overflows into the gap between electrodes causing electric leakage
Solution Approach 1:
An insulating layer is introduced as an intermediary between the bonding layer and the negative electrode fingers. This insulating layer prevents the bonding material from contacting the negative electrode fingers while still allowing the bonding layer to maintain electrical connection with the positive electrode fingers, thus resolving the contradiction between connection reliability and preventing electric leakage
Solution Approach 2:
The space between adjacent positive and negative electrode fingers is divided into separate regions: a bonding region where the bonding layer connects the soldering strip to positive electrode fingers, and an isolation region where the insulating layer prevents material overflow. This spatial segmentation allows the bonding material to be contained within its designated area, preventing electric leakage while maintaining connection reliability
2Reliability
If the positive and negative electrode fingers are alternately arranged to improve photoelectric conversion, then the photoelectric conversion efficiency is improved, but the gap between adjacent fingers becomes smaller increasing the risk of material overflow
Solution Approach 1:
Different regions of the solar cell structure are assigned different functional qualities: the bonding region between soldering strip and positive electrode fingers has high bonding material affinity, while the isolation region between positive and negative electrode fingers has high insulating properties. This local differentiation allows the alternating finger arrangement to maintain photoelectric conversion efficiency while preventing material overflow through the insulating layer in critical gap areas
Solution Approach 2:
The insulating layer serves as a mediator that fills and seals the gaps between alternately arranged positive and negative electrode fingers. This intermediary structure prevents bonding material from bridging the small gaps created by dense alternating arrangements, thus maintaining both photoelectric conversion efficiency and manufacturing precision
Data Source
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AI summary
The present application discloses a solar cell string and a photovoltaic module, belonging to the field of photovoltaic technologies. The solar cell string includes a solar cell and first connecting members. The solar cell includes a substrate and a plurality of first doped layers and a plurality of second doped layers formed on a first surface of the substrate. The first doped layers and the second doped layers all extend along a first direction and are alternately arranged along a second direction. A first isolation region is provided between the first doped layer and the adjacent second doped layer. First fingers are disposed on the first doped layers. Second fingers are disposed on the second doped layers. The first fingers and the second fingers all extend along the first direction. The second direction intersects with the first direction. The first connecting members extend along the second direction. The first connecting members are connected to the first fingers. In a first region of the first surface, intersections of the first connecting members and the second fingers are provided with a plurality of second insulating blocks in a one-to-one correspondence with the second fingers. Along the second direction, at least a part of the second insulating blocks extends into the first isolation regions adjacent thereto.