Rear-Side Bus Bar Layout in Photovoltaic Modules
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Solution Overview
Problem
The existing design of photovoltaic modules, where bus bars are arranged at the sides of cell strings, occupies significant space, reducing the area proportion of the cells and affecting efficiency.
Innovation Solution
The bus bar is positioned at the back surface of the cell, with a solder strip connecting it to the cell, featuring a bending section that is not parallel to the connecting section, allowing the bus bar to be partially within the cell string projection, reducing lengthwise space and misalignment to minimize stress and crack risks during lamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the bus bar is arranged at the sides of the cell string, then the bus bar can be easily connected to the cell, but the bus bar occupies significant space, reducing the area proportion of the cell
Solution Approach 1:
The bus bar is moved from a lateral arrangement (along the length direction) to a vertical arrangement (at the back surface), utilizing the thickness dimension. This dimensional transition allows the bus bar to occupy space in the thickness direction rather than the length direction, thereby increasing the cell area proportion while maintaining connectivity.
Solution Approach 2:
The bus bar is positioned within the projection of the cell string along the thickness direction, effectively nesting the bus bar within the spatial envelope of the cell assembly. This nested arrangement allows the bus bar to be integrated into the existing structure without adding lateral dimensions, thus preserving cell area.
2Device complexity
If the solder strip is arranged parallel to the cell edge, then the layout is simple, but stress concentration and crack risks increase during lamination
Solution Approach 1:
The solder strip is designed with a bending section that forms a curved or angled transition between the connecting section and the bus bar. This curved geometry distributes stress more evenly during lamination, avoiding the stress concentration that would occur with sharp corners or parallel arrangements, thereby reducing crack risks.
Solution Approach 2:
The solder strip's geometry is changed from a parallel straight configuration to an angled or bent configuration. This parameter change in the solder strip's shape allows for stress distribution during the lamination process, reducing the likelihood of hidden cracks while maintaining electrical connectivity.
Data Source
AI summary
Provided is a photovoltaic module, including a cell string, a bus bar, and at least one solder strip configured to connect the bus bar to a cell of the cell string. Along a thickness direction of the photovoltaic module, the bus bar is located at a side where a back surface of the cell is located, and at least part of a projection of the bus bar along the thickness direction Z of the photovoltaic module is located within a projection of the cell string. The solder strip includes a connecting section and a bending section, the connecting section is connected to the cell, the bending section bends towards the side where the back surface of the cell is located and is connected to the bus bar, and an extension direction of the bending section is not parallel to an extension direction of the connecting section.