Solar Cell Contact Sheet Interconnection With Embedded Conductors
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Solution Overview
Problem
The existing interconnection methods for solar cells, such as soldering tabbing wire, face challenges including microcracks in silicon wafers, lead usage issues, and increased power losses due to series resistance, especially with larger and more efficient solar cells.
Innovation Solution
A method involving the use of contact sheets with embedded structured electrically conductive elements, which are positioned and bonded to the solar cell components using a bonding material, eliminating the need for busbar contact regions and allowing for more flexible interconnection arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If soldering tabbing wire to metal busbar regions is used for interconnecting solar cells, then the interconnection process is well-established and reliable, but microcracks are formed in silicon wafers and power losses due to series resistance increase with larger cell areas
Solution Approach 1:
The patent extracts and eliminates the metal busbar regions from the solar cell surface, replacing them with conductive adhesive patterns directly applied to the cell. This removes the source of microcracks and reduces series resistance by providing multiple direct contact points across the cell surface, thereby resolving the contradiction between interconnection reliability and power losses.
Solution Approach 2:
The patent segments the interconnection approach by dividing the cell surface into multiple contact regions where conductive adhesive is applied in specific patterns. This segmentation allows current to be collected at multiple points rather than through large busbars, reducing series resistance while maintaining reliable connections without causing microcracks.
2Loss of energy
If the number of busbars on the cell is increased to reduce power losses due to series resistance, then power losses are reduced and metallization costs are lowered, but alignment complexity increases and adhesion is impacted due to reduced contact area
Solution Approach 1:
The patent merges the functions of busbars and interconnection material by using conductive adhesive that serves both purposes simultaneously. The conductive adhesive patterns are applied directly at the interconnection locations, eliminating the need for separate busbar formation and alignment processes, thereby reducing complexity while maintaining low series resistance through multiple contact points.
3Ease of manufacture
If conventional screen-printing of metal paste is used for cell metallization, then the process is well-established, but lead usage issues arise and metallization costs increase
Solution Approach 1:
The patent changes the material parameters of the metallization process by replacing traditional metal pastes containing lead and silver with conductive adhesives based on silver conductive epoxy or equivalent materials. This substitution maintains the screen-printing process simplicity while eliminating lead usage and reducing costly precious metal content, achieving both ease of manufacture and reduced material loss.
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 reduces power losses due to series resistance, lowers metallization costs, and eliminates the need for lead-based solders, while also providing a more flexible and cost-effective interconnection process for solar cells.
Implementation Method 1
activating the bonding material such that a bond and an electrically conductive coupling is formed between the at least one electrically conductive region and the exposed surface portion
Data Source
AI summary
This relates to a method of forming a device structure, including: providing at least one device component having front and rear device component surfaces and at least one electrically conductive region on the device component surfaces; providing at least one contact sheet including a polymeric material and at least one electrically conductive element with a non-circular cross-sectional shape and embedded in the polymeric material such that a surface portion of the electrically conductive element is exposed; applying a bonding material to one or both of the exposed surface portion and the electrically conductive regions on the device component surfaces; positioning the contact sheet relative to the device component such that the bonding material is located between the electrically conductive region and the exposed surface portion; activating the bonding material such that a bond and an electrically conductive coupling are formed between the electrically conductive region and the exposed surface portion.