Back-Contact Cell String Layout for Edge Stress Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
During the lamination process of photovoltaic modules, stress concentration occurs at the edges of solar cells due to height differences between welding strips and cells, leading to hidden cracking or fragmentation, and the flow of molten adhesive exacerbates this issue.
Innovation Solution
A back contact solar cell string group is designed with specific distance ratios between welding strips to distribute stress evenly, reducing the risk of cracking and fragmentation by optimizing the arrangement of welding strips and chamfered edges, and ensuring proper spacing to avoid short circuits and adhesive flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If welding strips are arranged close to the edges of solar cells to improve current collection, then current collection efficiency is improved, but stress concentration occurs at the edges causing hidden cracking or fragmentation
Solution Approach 1:
The patent applies local quality by creating different structural characteristics at different locations. Specifically, chamfered edges are provided at the edges of solar cells, and welding strips are positioned at specific distances from these chamfered edges. This localized modification allows the edges to have different properties (chamfered vs. non-chamfered) to optimize both current collection and stress distribution, resolving the contradiction between improving current collection and preventing cracking.
Solution Approach 2:
The patent applies preliminary action by pre-forming chamfered edges on solar cells before the lamination process. This preliminary structural modification prepares the edges to better distribute stress during subsequent welding and lamination operations, preventing cracking before it occurs rather than addressing it after stress concentration happens.
2Object-affected harmful factors
If distance between end welding strips of adjacent solar cell strings is large to prevent adhesive flow, then adhesive-induced pressure is reduced, but the overall module size increases
Solution Approach 1:
The patent applies parameter changes by optimizing the distance parameter between end welding strips of adjacent solar cell strings. By setting this distance within a specific range (0.6≤d2/d1<1.0, where d2 is the distance between end welding strips and d1 is the distance between adjacent welding strips), the patent achieves the optimal balance that prevents excessive adhesive flow while minimizing module size. This quantitative parameter optimization resolves the contradiction between preventing adhesive-induced pressure and maintaining compact module dimensions.
3Strength
If welding strips are positioned to minimize stress concentration, then cracking is reduced, but current collection efficiency decreases
Solution Approach 1:
The patent applies segmentation by dividing the edge region of solar cells into different segments: chamfered edges and non-chamfered edges. This segmentation allows different parts of the edge to serve different functions - the chamfered edges provide stress relief while the non-chamfered edges maintain good electrical contact for current collection. The welding strips are then positioned to connect these segmented regions, achieving both stress distribution and current collection goals.
Data Source
AI summary
The present application discloses a back contact solar cell string group and a photovoltaic module. In one example, a back contact solar cell string group includes at least two solar cell strings. Each solar cell string includes: multiple solar cells arranged along a second direction; and multiple welding strips, where two adjacent solar cells in a solar cell string are electrically connected by corresponding welding strips of the multiple welding strips arranged along a first direction, and a distance between two welding strips adjacent to each other along the first direction is d1. In each solar cell string, welding strips adjacent to two edges of the multiple solar cells along the first direction are end welding strips. A distance between two end welding strips of two solar cell strings adjacent to each other along the first direction is d2, 0.6≤d2/d1<1.