Photovoltaic Cell Wrap-Through Connection Short Circuit Prevention
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Solution Overview
Problem
Photovoltaic cells with metal wrap through connections (MWT) face issues of short circuits due to unintended current paths and local flaws, requiring complex additional processing measures to prevent these problems.
Innovation Solution
The solution involves providing an emitter layer on the back surface of the photovoltaic cell, with electrical isolation around the via connections to prevent short circuits, allowing for simpler manufacturing processes and reduced output impedance by applying electrode material on a supporting surface that is electrically isolated from lateral current, thereby reducing the risk of short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If metal wrap through connections (MWT) are used to provide terminals on the same surface, then the device complexity is reduced and ease of operation is improved, but short circuit risks increase due to unintended current paths through the via walls and local flaws
Solution Approach 1:
The harmful conductive material is extracted from the via walls by removing it before applying the emitter layer. This extraction eliminates the source of potential short circuits while preserving the beneficial MWT terminal configuration on the same surface.
Solution Approach 2:
The emitter layer is applied in advance to cover the via walls before the conductive paste is applied. This preliminary protective action prevents unintended current paths from forming, addressing the short circuit risk before it can manifest during subsequent processing steps.
2Reliability
If complex additional processing measures such as trenches and localized emitter layers are implemented to prevent short circuits, then reliability is improved, but manufacturing complexity and processing time increase
Solution Approach 1:
The manufacturing process is segmented into distinct sequential steps: removing conductive material, applying emitter layer, then applying conductive paste. This segmentation simplifies each individual step while ensuring reliable short circuit prevention through the systematic application of the emitter layer as a protective barrier.
3Reliability
If the emitter layer is applied on the back surface covering the via connections, then reliability is improved by preventing short circuits, but manufacturing precision requirements increase to ensure proper coverage and alignment
Solution Approach 1:
The emitter layer is applied in advance to cover the via walls and connections before any conductive paste or terminal structures are formed. This preliminary coverage ensures that even with variations in alignment, the via connections are protected from short circuits, as the emitter layer serves as a preventive barrier during subsequent processing steps.
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 approach simplifies the manufacturing process, reduces the risk of short circuits, and improves the electrical efficiency of the photovoltaic cell by ensuring that the emitter layer covers the via connections, leading to enhanced performance and reduced manufacturing complexity.
Implementation Method 1
a photovoltaic cell (e.g. a solar cell) wherein light excites free charge carriers, which give rise to an output voltage and current between and through output terminals of the cell
Data Source
Figure 1
Figure 2
Figure 3~8
AI summary
Known photovoltaic cells with wrap through connections have output terminals of both polarities on its back surface, one of which is coupled to the front surface via the wrap through connections. The invented solar cell is manufactured by creating an emitter layer on the back surface. Electrode material is applied in mutually separate first and second areas on the back surface. The electrode material in the first area contacts the emitter. The second area covers a surrounding of a hole that provides for the connection on the back surface. The electrode material in the second area lies on the emitter and around the second area the emitter is interrupted by a trench. On the front surface a further area of electrode material is applied over the hole. If necessary the electrode material in the second area on the back surface is applied on a supporting surface that is substantially electrically isolated from current flowing laterally through the emitter layer underneath the first area.