Thin Film Solar Cell Interconnection via Conductive Adhesive Lamination
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Solution Overview
Problem
The challenge in photovoltaic cell manufacturing lies in forming reliable series connections between thin-film cells without incurring high production costs, while minimizing the area covered by interconnection mechanisms to maintain efficiency and withstand mechanical stress, as traditional soldering methods damage thin-film coatings and adhesion issues lead to power losses.
Innovation Solution
The solution involves laminating multiple flexible thin-film photovoltaic cells in series to a transparent top sheet with a conductive grid pattern and a back sheet, using a conductive adhesive for interconnections, and employing a roll-to-roll process for efficient assembly, which includes cutting vias and applying dielectric material to prevent shorting and delamination, and integrating bypass diodes to manage shading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional soldering methods are used to form series connections between thin-film cells, then reliable electrical connections are achieved, but the thin-film coatings are damaged and production costs increase
Solution Approach 1:
The patent introduces a conductive adhesive as an intermediary material between the thin-film cells to establish electrical connections. This adhesive layer mediates the connection without requiring direct solder contact with the delicate thin-film coatings, thereby preventing coating damage while maintaining reliable electrical conductivity for series connections between cells
Solution Approach 2:
The patent replaces the traditional mechanical soldering process with a chemical bonding approach using conductive adhesive. Instead of using heat and mechanical pressure from soldering irons that can damage thin-film coatings, the adhesive chemically bonds to the cell surfaces and provides both mechanical attachment and electrical conductivity through its conductive properties
2Reliability
If traditional soldering methods are used to form series connections, then electrical connections are established, but production costs increase
Solution Approach 1:
The patent employs conductive adhesive as a low-cost alternative to expensive soldering materials and equipment. The adhesive can be applied through simple dispensing or printing processes that are much cheaper than soldering operations, and while the adhesive itself may have shorter-term stability characteristics, it provides sufficient reliability for the application at a fraction of the cost of traditional soldering
Solution Approach 2:
The patent changes the fundamental parameters of the connection process by transitioning from high-temperature soldering to room-temperature or low-temperature adhesive bonding. This parameter change eliminates the need for expensive soldering equipment, reduces energy consumption, and allows for simpler manufacturing processes that lower production costs while maintaining connection reliability
3Reliability
If interconnection mechanisms cover large areas of cells, then reliable connections are formed, but the efficiency is reduced due to increased shading
Solution Approach 1:
The patent segments the interconnection approach by using narrow conductive adhesive traces rather than large-area metal contacts. The adhesive is applied in thin lines or patterns that only cover the minimal necessary area to establish electrical connections between cells, leaving the majority of the cell surface exposed to light and maintaining high photosynthetic efficiency
Solution Approach 2:
The patent transitions from two-dimensional large-area metal contacts to one-dimensional narrow adhesive traces. By confining the conductive adhesive to linear paths that follow the cell edges or specific connection points, the interconnection mechanism occupies minimal surface area while still providing reliable electrical pathways, thereby reducing shading losses
4Loss of energy
If interconnection mechanisms are minimized, then shading is reduced, but mechanical stress resistance is compromised
Solution Approach 1:
The patent uses composite conductive adhesive materials that combine multiple functions in a single layer. These adhesives incorporate conductive fillers (such as metal particles or conductive polymers) within a flexible polymer matrix, providing simultaneous electrical conductivity, mechanical adhesion, and stress resistance. The composite structure allows thin adhesive traces to maintain mechanical integrity and withstand thermal and mechanical cycling despite covering minimal area
Solution Approach 2:
The patent changes the material parameters of the adhesive to achieve high mechanical strength at minimal thickness. By selecting adhesives with optimized viscosity, curing characteristics, and elastic modulus, the system achieves strong bonding and stress resistance in thin layers that minimize shading while maintaining the mechanical robustness needed to withstand installation and operational stresses
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 interconnection costs, minimizes the area covered by interconnection mechanisms, enhances mechanical stress resistance, and maintains high efficiency by establishing reliable electrical connections and preventing power losses due to shading or mechanical stress.
Implementation Method 1
using a conductive adhesive for interconnections
Implementation Method 2
The basic mechanism for this conversion is the photovoltaic effect, first observed by Antoine-Cesar Becquerel in 1839
Implementation Method 3
applying dielectric material to prevent shorting
Data Source
AI summary
Photovoltaic modules may include multiple flexible thin film photovoltaic cells electrically connected in series, and laminated to a substantially transparent top sheet having a conductive grid pattern facing the cells. Methods of manufacturing photovoltaic modules including integrated multi-cell interconnections are provided. Methods may include steps of coordinating, integrating, and registering multiple rolls of substrates in continuous processes.