Back-Contact Solar Cell String Assembly Without Soldering Warpage
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Solution Overview
Problem
The soldering of solder strips to back contact solar cells leads to warping and increased defect rates due to unsolved soldering stress, which is not applicable to back contact solar cells where both electrodes are on the rear surface.
Innovation Solution
Applying an insulating adhesive on the rear surface of the solar cells and curing it with a UV lamp to secure the solder strip, followed by applying a reinforcing adhesive to enhance stability and prevent warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If soldering is used to fixedly connect the solder strip to the solar cell, then the solder strip can be securely attached, but soldering stress causes warping of the back contact solar cell, increasing the defective rate
Solution Approach 1:
The patent replaces the thermal-mechanical soldering process with a chemical bonding process using adhesive. The adhesive is applied between the solder strip and the solar cell back contact, curing to form a strong bond without generating thermal stress that causes warping. This substitution of bonding mechanism eliminates the harmful thermal effects while maintaining connection strength.
Solution Approach 2:
The patent changes the bonding temperature parameter from high temperature (soldering) to room temperature or low temperature (adhesive curing). This parameter change prevents thermal stress accumulation that leads to solar cell warping, while still achieving adequate bond strength through chemical adhesion rather than metallurgical bonding.
2Reliability
If soldering is used to connect the solder strip, then electrical connection is achieved, but the process increases manufacturing complexity and defective rate
Solution Approach 1:
The patent merges the mechanical bonding function and electrical connection function into a single adhesive layer. The adhesive simultaneously provides structural support to prevent warping and ensures electrical conductivity for the back contact solar cell connection, eliminating the need for separate soldering operations and reducing process complexity.
Solution Approach 2:
The patent replaces the complex soldering process (requiring temperature control, flux application, precise timing) with a simpler adhesive application and curing process. This substitution maintains electrical connection reliability while significantly reducing manufacturing process complexity and the risk of soldering-related defects.
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 method stabilizes the connection between the solder strip and solar cells, reducing warping and improving the yield and reliability of the photovoltaic module by preventing hidden cracks and splits.
Implementation Method 1
curing the insulating adhesive by irradiation with an ultraviolet lamp
Data Source
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AI summary
A method for manufacturing a photovoltaic module, including: providing solar cells and a solder strip; applying an insulating adhesive on a rear surface of the solar cells; laying the solar cells along a first direction; placing the solder strip on the solar cells so that, along the first direction, one end of the solder strip abuts against a positive busbar of one of the solar cells, and the solder strip is bonded to the insulating adhesive on the solar cells; and the other end of the solder strip abuts against a negative busbar of another one of the solar cells adjacent thereto, and the solder strip is bonded to the insulating adhesive on the solar cells; curing the insulating adhesive by irradiation with an ultraviolet lamp, so that the plurality of solar cells are connected through the solder strip to form a solar cell string; arranging the solar cell strings along a second direction, and connecting two adjacent solar cell strings in series and/or in parallel to form a photovoltaic cell pack; providing a front packaging structure and a back packaging structure; and laminating the front packaging structure, the photovoltaic cell pack, and the back packaging structure to form the photovoltaic module, which can reduce the possibility of warping of the back contact solar cells during the arrangement of the solder strip.