Solar Module Back Contact Foil Cut-Outs for Stronger Bonding
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Solution Overview
Problem
The bonding between the middle encapsulant and the copper of the back contact foil, and the copper to the polymer of the back contact foil, is weak, leading to delamination issues in solar modules.
Innovation Solution
The back contact foil is modified with cut-outs through which the back encapsulant layer bonds directly to the middle encapsulant layer and/or the solar cells, enhancing the bonding strength, and a re-enforcement layer with a thermal expansion coefficient matching the transparent surface is added for improved rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the middle encapsulant layer bonds to the back contact foil using conductive glue through cut-outs, then electrical connection is achieved, but the bonding strength between layers is weak leading to delamination
Solution Approach 1:
The back contact foil is segmented with cut-outs that align with electrodes, creating discrete bonding zones. This segmentation allows the encapsulant to bond directly to both the foil and solar cells at specific locations, distributing stress and improving overall bonding strength while maintaining electrical connectivity through the cut-out regions.
Solution Approach 2:
The back contact foil is nested between the middle and back encapsulant layers, with cut-outs allowing the encapsulants to interlock with the solar cell electrodes. This nested arrangement creates multiple bonding interfaces (encapsulant-to-foil and encapsulant-to-cell), reinforcing the layer structure and preventing delamination.
2Strength
If a re-enforcement layer is added to improve rigidity, then structural strength is enhanced, but device complexity increases
Solution Approach 1:
A re-enforcement layer composed of glass fibers embedded in resin is added to the back encapsulant layer. This composite material provides enhanced rigidity and structural strength to the module while maintaining flexibility. The glass fiber reinforcement distributes mechanical stresses and prevents cracking, significantly improving module durability.
Solution Approach 2:
The re-enforcement layer is strategically positioned at the back of the module where structural support is most needed. The glass fiber orientation and density can be optimized locally to provide maximum rigidity in critical areas while minimizing overall weight and complexity. This localized reinforcement approach enhances strength without unnecessarily increasing device complexity throughout the entire structure.
Data Source
AI summary
The invention relates to a solar module with improved bonding. The solar module (100) comprises a front encapsulant layer (104), solar cells (106), a middle encapsulant layer (108), a back contact foil (210b) with a patterned copper pattern (210b) thereon, and a back encapsulant layer (112). Inventors found that, when producing such a solar module, the bonding between the middle encapsulant layer and the copper side of the back contact foil was insufficient. A solution is found in providing cut-outs in the back contact foil through which the back encapsulant layer can bond to the middle encapsulant layer and/or the solar cells.