IBC Solar Cell Edge Busbar Layout for Lower Stress and Recombination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional interdigitated back contact (IBC) solar cells face issues with stress concentration at the edges due to edge busbars, leading to cracks and reduced photoelectric conversion efficiency due to long-distance carrier transport and recombination loss.
Innovation Solution
The solar cell design includes alternating conductive doped portions with varying dopant concentrations and sub-fingers connected via doped portions, ensuring even distribution of N-type and P-type regions, reducing recombination loss and stress concentration by preventing edge busbars from being excessively close to the edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If edge busbars are placed close to the edges to improve electrical contact, then electrical conductivity is improved, but stress concentration increases leading to cracks and reduced reliability
Solution Approach 1:
The edge busbar structure is segmented into multiple sub-busbars spaced apart from each other and from the cell edges. This segmentation distributes the mechanical stress that would otherwise concentrate at single points, reducing crack formation while maintaining adequate electrical contact through the distributed contact points along the edge
Solution Approach 2:
Different regions of the cell edge are assigned different functions: sub-busbars provide electrical contact at specific locations while leaving gaps between them to reduce stress concentration. The doped regions are also locally optimized with varying dopant concentrations to balance electrical performance and mechanical stability at different positions
2Device complexity
If carriers are transported over long distances to reach central electrodes, then electrode simplification is achieved, but recombination loss increases reducing photoelectric conversion efficiency
Solution Approach 1:
The electrode collection path is extended from the front surface to the back surface of the cell. Carriers generated throughout the cell volume are collected via back-contact electrodes, utilizing the third dimension (cell thickness) to provide collection paths that avoid long lateral transports while maintaining structural simplicity
Solution Approach 2:
Heavily doped intermediary regions are introduced between the intrinsic cell regions and the metal electrodes. These doped regions act as carrier collection channels that facilitate efficient carrier transport to electrodes while minimizing recombination losses through their high carrier concentration and improved conductivity
3Ease of manufacture
If uniform dopant concentration is used in doped portions, then manufacturing simplicity is maintained, but carrier collection efficiency decreases due to insufficient conductivity variation
Solution Approach 1:
Different dopant concentrations are applied to different regions: heavily doped regions near electrodes provide high conductivity for efficient carrier collection, while lightly doped regions maintain good optical and electrical properties. This local differentiation optimizes carrier collection efficiency without requiring complex multi-step doping processes
Solution Approach 2:
The dopant concentration parameter is varied systematically across different regions of the cell. By changing the dopant concentration from high near electrodes to low in bulk regions, the patent optimizes the balance between electrical conductivity for carrier collection and optical properties for light absorption, improving overall cell efficiency
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 design enhances the photoelectric conversion efficiency by minimizing recombination loss, reducing series resistance, and improving the reliability of the solar cell by mitigating cracks during soldering.
Implementation Method 1
A solar cell is an apparatus that converts light energy of the sun into electric energy. The solar cell generates carriers by using a photovoltaic effect principle
Implementation Method 2
First conductive doped portions and second conductive doped portions are arranged in the edge region and are alternatingly arranged in the first direction. The first conductive doped portions have a conductivity type different from the second conductive doped portions.
Data Source
AI summary
Disclosed are a solar cell and a photovoltaic module. In the solar cell, first and second conductive doped portions are arranged in an edge region of a first surface of a substrate. Each first conductive doped portion includes a first doped portion and second doped portions disposed on two opposite sides of the first doped portion, and a dopant concentration of the first doped portion is greater than that of the second doped portions. A passivation layer is disposed on the first surface. The second edge fingers are disposed on the second conductive doped portions respectively. Each first edge finger includes a first sub-finger and a second sub-finger, disposed on the second doped portions respectively. The second sub-finger is connected to the first sub-finger via the first doped portion. An edge busbar disposed on the passivation layer and on the first doped portion is connected to the second edge fingers.