Solar Cell Shading Loss Reduction via Segmented Bypass and Doped Regions
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Solution Overview
Problem
Conventional solar cell modules with bypass diodes suffer significant power generation performance loss when solar cells are shaded, as the entire string unit is bypassed, leading to reduced output from unshaded cells.
Innovation Solution
A solar cell design featuring a conductive-type silicon substrate with a low-doped region and a highly doped region, where the highly doped region has a higher dopant concentration, allowing electric current to flow to shaded cells at a lower voltage drop, thereby reducing power generation loss when cells are shaded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bypass diode is connected in parallel to a string unit, then the string unit can be bypassed when solar cells are shaded, but power generation performance of unshaded cells in the same string unit is lost
Solution Approach 1:
The patent divides the string unit into multiple independently controllable branches, where each branch contains a subset of solar cells. When shading occurs in one branch, only that branch is bypassed while other branches continue to generate power. This segmentation prevents the complete bypass of the entire string unit, thereby maintaining productivity while ensuring reliability under partial shading conditions.
Solution Approach 2:
The patent implements different bypass configurations for different regions within the string unit. By creating multiple bypass diodes corresponding to different branches, the system applies localized protection only where shading occurs. This allows unshaded regions to continue contributing to power generation, resolving the contradiction between reliability and productivity.
2Reliability
If the entire string unit is bypassed when one cell is shaded, then the shaded cell is protected, but all cells in the string unit fail to contribute to power generation
Solution Approach 1:
The string unit is segmented into multiple branches with individual bypass diodes. When one cell is shaded, only the specific branch containing that cell is bypassed, while other branches remain active. This segmentation minimizes energy loss by keeping unaffected cells operational, thus resolving the contradiction between protection and energy utilization.
Solution Approach 2:
Instead of bypassing the entire string unit (excessive action), the patent applies bypass protection only to the affected branch (partial action). This partial bypass approach provides sufficient protection against shading damage while minimizing the loss of power generation from unshaded cells.
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 design effectively suppresses power generation loss in solar cell modules by enabling electric current flow to shaded cells, ensuring that unshaded cells continue to contribute to power generation, thus maintaining performance even under shading conditions.
Implementation Method 1
a first main-surface side highly doped region provided between the low-doped region and the second conductive-type amorphous silicon layer and having a concentration of a first conductive-type dopant higher than that in the low-doped region, allowing electric current to flow to shaded cells at a lower voltage drop
Data Source
AI summary
An n-type low-doped region and a first main-surface side highly doped region, which has an n-type dopant concentration higher than that in the n-type low-doped region, are provided in an n-type crystalline silicon substrate. The first main-surface side highly doped region is arranged between the n-type low-doped region and a p-type amorphous silicon layer.