Busbar-Free PV Module Stringing for Pre-Lamination Solder Inspection
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Solution Overview
Problem
The current photovoltaic module manufacturing process using low-temperature solder ribbons to replace busbars in heterojunction solar cells faces challenges with unreliable ohmic contacts and quality risks due to undetectable defects like cold solder joints and over-soldering, leading to low mass production yield rates.
Innovation Solution
A method is introduced to form a reliable ohmic contact between electrical connecting members and solar cell fingers before lamination, allowing for defect detection and repair, using high-temperature resistant materials and protective members to ensure stable connections and improve yield rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If low-temperature solder ribbons are used to replace busbars and ohmic contact is formed during lamination, then metal paste consumption is reduced, but soldering quality cannot be detected before encapsulation and defects cannot be repaired
Solution Approach 1:
The patent performs soldering and quality detection before encapsulation rather than during lamination. The electrical connecting members are soldered to the solar cell fingers, then the battery string is detached for quality testing, allowing defects to be identified and repaired before final encapsulation.
Solution Approach 2:
The manufacturing process is divided into separate stages: soldering stage, detachment stage, quality detection stage, and encapsulation stage. This segmentation allows quality testing to be performed on the battery string before encapsulation, enabling defect detection and repair.
2Ease of manufacture
If low-temperature solder ribbons are used to replace busbars, then manufacturing cost is reduced, but mass production yield rate decreases due to undetectable defects
Solution Approach 1:
Quality detection is performed before encapsulation to identify defects early in the manufacturing process. This preliminary quality control allows defective products to be repaired or discarded before final assembly, improving the overall yield rate.
Solution Approach 2:
The patent implements a feedback mechanism where quality检测结果 is used to guide repair actions. Defects such as cold solder joints and over-soldering are detected, and repair measures are taken based on the detection results before final encapsulation.
3Reliability
If electrical connecting members are fixed to solar cell fingers before lamination, then ohmic contact can be formed, but defects like cold solder joints and over-soldering occur without detection
Solution Approach 1:
The battery string is detached from the encapsulation structure after soldering but before final encapsulation, allowing quality testing to be performed on the electrical connecting members and their contact with solar cell fingers. This preliminary detection enables identification of defects before they are enclosed.
4Device complexity
If quality test is performed after encapsulation, then manufacturing process is simplified, but defects cannot be repaired and yield rate decreases
Solution Approach 1:
The manufacturing process is segmented into distinct stages with quality testing performed at an intermediate stage before encapsulation. The battery string is detached for quality testing, allowing defects to be identified and repaired before final assembly, improving yield rate despite increased process complexity.
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 approach enhances the reliability and mass production yield of photovoltaic modules by enabling direct quality testing and repair of defects, using high-temperature resistant materials and eliminating light shading, thus improving electrical conductivity and reducing production costs.
Implementation Method 1
forming an effective ohmic contact between the low-temperature solder ribbons and the fingers of the heterojunction solar cells by utilizing heat generated during lamination
Data Source
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AI summary
The present disclosure discloses a photovoltaic module manufacturing method and a photovoltaic module. The manufacturing method comprises: step a1, fixing a plurality of cells by means of electrical connecting members to form a battery string structure, wherein the cells comprise a first surface and a second surface which are opposite to each other, and the first surface and the second surface of the cells are each provided with a plurality of fingers and no busbar, step b1, constructing an electrical connection between the cells and the electrical connecting members in the battery string structure to form a battery string; and step c1, performing quality test on the battery string, and manufacturing a photovoltaic module by using a qualified battery string.