Integrated Metal Foil Back Contact for Solar Cell Interconnection
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Solution Overview
Problem
Existing photovoltaic solar cell interconnection methods are costly and lack mechanical stability, requiring external connectors and rigid metallic structures that can cause series resistance losses and mechanical stress in solar cell modules.
Innovation Solution
A method involving a metal foil that projects beyond the edges of solar cells for electrical connection, acting as both a back-side contacting structure and a cell connector, providing a flexible and cost-effective solution that eliminates the need for external connectors and reduces series resistance by using point contacts and an insulating layer to prevent unwanted electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external metallic cell connectors are used to interconnect solar cells, then electrical connection is achieved, but device complexity and cost increase
Solution Approach 1:
The patent combines the back-side contacting function and the cell connector function into a single integrated metal foil structure. The metal foil extends from the back side of the solar cell and directly connects to the adjacent cell, eliminating the need for separate external connectors. This integration reduces device complexity while maintaining reliable electrical connection.
Solution Approach 2:
The metal foil serves multiple functions simultaneously: it provides back-side contacting for charge carrier collection and acts as the cell connector for interconnecting adjacent solar cells. This multi-functionality reduces the number of components needed and simplifies the overall module structure.
2Reliability
If rigid metallic structures are used for cell connection, then electrical conductivity is achieved, but mechanical stability decreases due to stress and series resistance losses
Solution Approach 1:
The patent employs a flexible metal foil instead of rigid metallic connectors. The foil's flexibility allows it to accommodate mechanical stress and thermal expansion without causing damage or increasing series resistance. This thin film structure reduces mechanical stress on the solar cells while maintaining effective electrical connection.
3Ease of operation
If metal foil projects beyond solar cell edges by at least 200 μm, then cell connection capability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The metal foil is designed to extend beyond the solar cell edges during the manufacturing process, creating a pre-formed connection structure. This preliminary extension facilitates subsequent alignment and connection operations, as the foil already provides the necessary overlap and contact area with adjacent cells, reducing the precision demands during assembly.
Data Source
AI summary
A method for producing a photovoltaic solar cell, including the method steps: A. providing at least one solar cell precursor having at least one base and at least one emitter; B. providing a metal film on a back side of the solar cell precursor, so that the metal film is electrically conductively connected to the base or the emitter, the metal film being formed as an integral component of the back side contact and the solar cell being terminated on the back side. The at least one cell connection region on at least one side of the metal film overhangs the edge of the solar cell precursor by at least 1 mm, preferably by at least 3 mm.