Back Contact Solar Cell String Insulation and Bus Bar Design
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Solution Overview
Problem
Conventional back contact solar cell strings face challenges in accurate cell alignment and complex manufacturing processes due to the small wire widths and large quantity of emitter and base contact electrodes, leading to potential short circuits during serial connection.
Innovation Solution
A back contact solar cell string design featuring insulation layers covering non-electrically connected electrode regions, with first bus bars connected to uncovered electrode regions, and optional conductive adhesives or solder pastes for electrical connection, simplifying alignment and reducing the risk of short circuits, while reflection structures on bus bars enhance light utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional back contact solar cells are serially connected to form a cell string, then the solar cell module can be assembled, but accurate cell alignment is required during welding which makes the process complex
Solution Approach 1:
The patent introduces an insulation layer as an intermediary element between adjacent cell pieces. This insulation layer extends beyond the electrode regions to create isolation zones, serving as a mediator that prevents short circuits between adjacent cells. The insulation layer acts as a buffer that compensates for alignment deviations, allowing the welding process to tolerate certain positioning errors without causing electrical short circuits.
Solution Approach 2:
The patent applies insulation layers to the cell pieces before the serial connection and welding process. This preliminary action of pre-isolating the electrode regions ensures that even if alignment deviations occur during subsequent welding, the insulation layers are already in place to prevent short circuits. The insulation structure is prepared in advance to accommodate potential positioning errors.
2Reliability
If the emitter and base contact electrodes are connected during cell alignment for welding, then electrical connection is achieved, but short circuit of the cell piece is caused due to small wire widths and large quantity of electrodes
Solution Approach 1:
The insulation layer serves as a protective intermediary that physically separates adjacent electrode regions. By extending the insulation layer beyond the electrode boundaries, it creates a safety margin that prevents unintended electrical contact between adjacent cells. This intermediary structure reduces the harmful effect of short circuits caused by alignment deviations or electrode contact during welding.
Solution Approach 2:
The patent employs insulation layers as a preventive measure that cushions against potential short circuit risks before they can occur. The insulation layers are applied in advance to cover not only the electrode regions but also the areas where short circuits might occur due to alignment errors. This beforehand cushioning protects the cell string assembly from the harmful effect of short circuits during the welding process.
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
The solution simplifies the manufacturing process by reducing the need for precise cell alignment, prevents short circuits, and increases light utilization through secondary reflection, thereby enhancing the energy conversion efficiency and power output of the solar cell module.
Implementation Method 1
the reflection structures are disposed on the first bus bars, so that light can be reflected back to glass in a manufactured cell module, and then reflected to an adjacent cell piece through the glass
Data Source
AI summary
A back contact solar cell string includes: at least two cell pieces, where each cell piece comprises positive electrode regions and negative electrode regions alternately disposed with each other; insulation layers, covering the positive electrode regions on one side of the cell piece and the negative electrode regions on another side of the cell piece; and a first bus bar, connected to two adjacent cell pieces and electrically connected to the positive electrode regions and the negative electrode regions in the two adjacent cell pieces that are not covered by the insulation layers.