Back-Contact Cell Electrode Layout for Lower Paste Use and Stress
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Solution Overview
Problem
Existing back contact solar cells face challenges such as high production costs, low reliability, and poor photoelectric conversion performance due to issues with electrode pattern design, including the use of low-temperature pastes, high paste consumption, and stress concentration during module assembly.
Innovation Solution
The proposed electrode structure for a back contact cell includes first and second fingers, a first busbar, first pad points, and first connection electrodes, with bent fingers that are not in contact with the busbar or pad points, allowing for efficient current collection without the need for extensive insulation paste, thereby reducing costs and improving reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If metal layers are removed from the front surface of the solar cell, then light absorption is improved and optical losses are reduced, but the cell requires a completely different contact structure that increases manufacturing complexity
Solution Approach 1:
The patent inverts the conventional solar cell structure by moving all metal contacts to the rear surface instead of having them on the front surface. This inversion allows the front surface to be fully optimized for light absorption without any metal obstructions, while the rear surface houses all electrical contacts. The inverted T-shaped contact structure integrates multiple functions (emitter contact, base contact, and rear surface field) into a unified rear-contact architecture.
Solution Approach 2:
The patent transitions from a planar front-contact layout to a three-dimensional rear-contact structure with vertical and horizontal components. The T-shaped contact structure extends vertically from the rear surface into the semiconductor substrate, creating multiple contact regions at different depths and positions. This dimensional transformation allows efficient electrical collection while maintaining optimal optical properties.
2Reliability
If a selective emitter is formed in a first region and a rear surface field is formed in a second region, then electrical contact is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent divides the rear surface into distinct functional regions: a first region with selective emitter for one polarity contact, a second region with rear surface field for the opposite polarity contact, and intermediate regions for additional electrical connections. This segmentation allows each region to be optimized for its specific electrical function while maintaining a unified manufacturing process that forms all regions simultaneously through selective doping and deposition techniques.
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 electrode structure enhances the reliability and reduces costs by eliminating the need for high-paste consumption and improving photoelectric conversion efficiency by minimizing recombination losses and series resistance.
Implementation Method 1
The back contact cell comprises a substrate, an n-type semiconductor layer formed on the substrate, a p-type semiconductor layer formed on the n-type semiconductor layer
Data Source
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AI summary
The disclosure provides an electrode structure of a back contact cell, a back contact cell, a back contact cell module, and a back contact cell system. The electrode structure includes: first fingers, configured to collect a first polarity region; second fingers, configured to collect a second polarity region; a first busbar, disposed on a side of the back contact cell close to a first edge and connected to the first fingers; first pad points; and first connection electrodes, respectively connected to the first busbar and the first pad points. A distance between each of the first pad points and the first edge is greater than a distance between the first busbar and the first edge. The electrode structure can improve the reliability, reduce the costs, increase the product yield, and ensure excellent photoelectric conversion efficiency.