Shingled Solar Cell Interconnects With Flexible Adhesive Joints
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Solution Overview
Problem
Traditional solar cell module designs require gaps between cells for interconnects, reducing the active power generation area and potentially causing stress on interconnects, which can lead to efficiency losses and mechanical issues.
Innovation Solution
The design features a string of solar cells arranged in a shingled manner with electrically conductive interconnects sandwiched between cells, and flexible joints made of cured liquid polymeric adhesive that are electrically insulating and have a Shore A hardness of less than 80, to reduce stress on interconnects and eliminate gaps between cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If traditional solar cell module designs are used with gaps between cells for interconnects, then interconnects can be properly positioned and electrically connected, but the active power generation area is reduced and stress on interconnects increases
Solution Approach 1:
The interconnect is nested within the flexible joint material, which is applied to the rear surface of the first solar cell. The flexible joint material completely encloses the interconnect, protecting it from environmental damage and mechanical stress while eliminating the need for gaps between cells. This nesting approach allows the interconnect to be embedded within the adhesive material rather than exposed between cells.
Solution Approach 2:
The flexible joint material serves as an intermediary substance that simultaneously provides electrical insulation, mechanical protection, and stress distribution for the interconnect. This mediator material allows the interconnect to be positioned and protected while eliminating gaps between solar cells, thus increasing the active power generation area.
2Reliability
If interconnects are exposed between solar cells, then electrical connection is achieved, but mechanical stress and potential damage to interconnects increases
Solution Approach 1:
The flexible joint material performs multiple functions simultaneously: it provides electrical insulation, mechanical protection, stress distribution, and structural bonding between cells. This multi-functional approach eliminates the need for separate protective structures around the interconnect, simplifying the overall device complexity while improving reliability.
Solution Approach 2:
The flexible joint material undergoes parameter changes from liquid to cured solid state, transforming from an application state to a protective state. This parameter change allows the material to be easily applied in liquid form and then provides rigid protection when cured, protecting the interconnect without adding complex structural elements.
3Strength
If rigid adhesive is used to bond solar cells, then strong mechanical bonding is achieved, but stress on interconnects and inability to withstand thermal cycling increases
Solution Approach 1:
The flexible joint material utilizes parameter changes in its physical properties, specifically its Shore A hardness being less than 80, indicating a soft, flexible state that can accommodate thermal expansion and contraction. This parameter specification ensures the material maintains bonding strength while providing the flexibility needed for thermal cycling resistance.
Solution Approach 2:
The flexible joint material acts as a flexible film or layer between solar cells, providing mechanical bonding while accommodating dimensional changes due to thermal cycling. This flexible layer absorbs stress that would otherwise be transmitted to the rigid interconnect and solar cell structures, enabling the assembly to withstand repeated thermal cycles.
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 configuration enhances the mechanical performance and efficiency of solar modules by reducing stress on interconnects, minimizing power losses due to gaps, and improving the module's ability to withstand thermal cycling and mechanical loads.
Implementation Method 1
The flexible joint is in contact with the rear surface of the first solar cell, with the front surface of the second solar cell, and with the electrically conductive interconnect
Implementation Method 2
The cured liquid polymeric adhesive from the flexible joint is electrically insulating
Implementation Method 3
The soft adhesive material of the flexible joint reduces stress in the solar cell overlap region
Implementation Method 4
solar radiation impinging on the surface of, and entering into, the substrate of a solar cell creates electron and hole pairs in the bulk of the substrate. The electron and hole pairs migrate to p-doped and n-doped regions in the substrate, thereby creating a voltage differential between the doped regions
Data Source
AI summary
A string of shingled solar cells is disclosed. The string of shingled solar cells has flexible joints connecting the solar cells made from cured liquid polymeric adhesive. An electrically conductive interconnect passes through the flexible joint. The string of shingled solar cells also has interconnect reinforcements made from cured liquid polymeric adhesive to improve interconnect adhesion to the front surface of the solar cells.