Backplane Reinforcement for Thin Solar Cell Substrates
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Solution Overview
Problem
Back-contact solar cells face challenges such as mechanical support and electrode positioning accuracy due to their thin substrate thickness, leading to cracking and shunting issues, which affect manufacturing yield and efficiency.
Innovation Solution
A method involving a backplane structure with interdigitated patterns of base and emitter electrodes, forming conductive plugs, and attaching a backplane with a similar pattern to create electrical interconnects, providing mechanical reinforcement and improved conductivity for solar cell substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the substrate thickness is reduced to minimize material usage and cost, then the mechanical strength and rigidity deteriorate, causing substrate cracking during processing
Solution Approach 1:
The substrate is divided into a thin active layer and a separate support structure (backplane with reinforcement ribs). The thin silicon layer (1-100 μm) provides photovoltaic function while the backplane with ribs provides mechanical support, allowing material reduction without sacrificing strength.
Solution Approach 2:
The invention uses a composite structure combining thin silicon substrate with a rigid backplane (glass or plastic) featuring reinforcement ribs. This composite design allows the thin substrate to maintain mechanical integrity during processing while minimizing material usage.
2Productivity
If the substrate thickness is reduced to increase light absorption efficiency, then the manufacturing precision deteriorates due to substrate cracking and handling difficulties
Solution Approach 1:
The backplane with reinforcement ribs acts as an intermediary support structure between the thin substrate and the handling equipment. This mediator provides the necessary mechanical support during manufacturing processes, enabling precise handling of thin substrates without cracking.
Solution Approach 2:
The backplane structure is prepared in advance with reinforcement ribs before the thin substrate is attached. This preliminary action ensures mechanical support is already in place, preventing substrate cracking during subsequent processing steps and enabling high manufacturing precision.
3Reliability
If the electrode width is increased to reduce series resistance, then the manufacturing precision deteriorates due to co-planar interconnection requirements and electrode positioning accuracy
Solution Approach 1:
The invention transitions from planar electrode layouts to three-dimensional co-planar interconnections with vertical plugs. This dimensional change allows electrodes to be positioned with higher precision in the vertical dimension while maintaining wide horizontal traces for low resistance, resolving the conflict between electrode width and positioning accuracy.
Solution Approach 2:
Conductive plugs are formed in advance within the substrate before the backplane is attached. This preliminary action establishes precise vertical alignment features that guide the backplane electrodes, ensuring accurate positioning even with wide electrode traces required for low series resistance.
Data Source
AI summary
Fabrication methods and structures relating to backplanes for back contact solar cells that provide for solar cell substrate reinforcement and electrical interconnects are described. The method comprises depositing an interdigitated pattern of base electrodes and emitter electrodes on a backside surface of a semiconductor substrate, forming electrically conductive emitter plugs and base plugs on the interdigitated pattern, and attaching a backplane having a second interdigitated pattern of base electrodes and emitter electrodes at the conductive emitter and base plugs to form electrical interconnects.