PV Module Bus Local Widening for Interconnection Reliability
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Solution Overview
Problem
Existing photovoltaic module manufacturing techniques face challenges in achieving reliable mechanical and electrical interconnections between metal strips and photovoltaic cells due to alignment issues, stress on collection fingers, and irregularities in metallization thickness, which affect performance and longevity.
Innovation Solution
Incorporating local widenings on the buses at the electrical connection zones with the collection fingers, allowing for a wider total width at these points to accommodate misalignments and reduce stress, while using techniques like 'Dual Print' or 'Double Print' to minimize material consumption and improve alignment precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the width of the bus is reduced to match the width of the metal strip, then material consumption is reduced and shading is minimized, but alignment precision deteriorates and stress concentration increases
Solution Approach 1:
The bus width is varied locally: it is narrow in most regions to minimize material consumption and shading, but locally widened at electrical connection zones to accommodate misalignment and reduce stress. This local quality variation resolves the contradiction by optimizing different regions for different functions.
Solution Approach 2:
The local widening of the bus at electrical connection zones is prepared in advance during the metallization process, before the interconnection step. This preliminary action ensures that sufficient contact area and alignment tolerance are already in place, preventing stress concentration and alignment issues during subsequent assembly.
2Manufacturing precision
If the width of the bus is increased to improve alignment tolerance, then alignment precision is improved and stress is reduced, but material consumption increases and shading increases
Solution Approach 1:
Instead of uniformly increasing the bus width, the invention applies local widening only at electrical connection zones where alignment tolerance is needed. This resolves the contradiction by providing alignment tolerance only where necessary, minimizing material consumption in non-critical regions.
Solution Approach 2:
The bus is segmented into different width zones: narrow sections for material efficiency and wide sections at electrical connection zones for alignment tolerance. This segmentation allows the system to achieve both low material consumption and sufficient alignment tolerance simultaneously.
3Loss of energy
If collection fingers are made narrower to reduce shading, then shading is reduced and light absorption is improved, but mechanical strength deteriorates and stress concentration increases
Solution Approach 1:
Collection fingers are made narrow in most regions to minimize shading and maximize light absorption, but are locally reinforced or widened at electrical connection zones where mechanical strength is critical. This local quality variation resolves the contradiction between minimizing shading and maintaining mechanical strength.
Data Source
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AI summary
A photovoltaic module comprises several photovoltaic cells each comprising at least one collection finger (2) oriented in a first direction of elongation (D1) and at least one bus (3) oriented in a second direction of elongation (D2) forming an angle with the first direction of elongation, in particular an angle of 90 degrees. The bus (3) comprises, at the level of a zone of electrical linking (4) between the bus (3) and the collection finger (2), at least one local widening (Le) of the width (Lb) of the bus (3) in the first direction of elongation (D1). The ratio of the length (We) along the second direction (D2) in which the local widening (Le) of the width (Lb) of the bus (3) is effected to the width (Wd) of the corresponding collection finger (2) along the second direction (D2) is strictly greater than one. The photovoltaic cells are electrically connected together by way of at least one metallic strip (5) which are interconnected with at least one bus (3) of the photovoltaic cells. The total width (Lt) of the bus (3) at the level of a local widening (Le) is strictly greater than the width (Lr) of the metallic strip (5) in the first direction (D1). The invention also relates to a method of fabricating the photovoltaic module.