High-Concentration Solar Cell Trapezoid Electrode Current Distribution
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Solution Overview
Problem
High-concentration solar cells face issues with current crowding and local overheating due to uneven current distribution, which reduces photocurrent transmission and photoelectric conversion efficiency.
Innovation Solution
The design of a high-concentration solar cell chip features a primary grid composed of isosceles trapezoid structures with evenly distributed secondary grid connections, along with a four-layer upper patterned electrode structure for optimized ohmic contact and conductivity, preventing current crowding and enhancing illumination area utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional rectangular primary grid structure is used, then manufacturing is simple, but current distribution becomes uneven causing current crowding
Solution Approach 1:
The primary grid structure is changed from a traditional symmetric rectangular shape to an asymmetric isosceles trapezoid shape. The trapezoid's longer base is positioned at the lead soldering region while the shorter base is at the opposite side. This asymmetric geometry creates multiple current flow paths with different lengths and resistances, naturally distributing current more uniformly across the grid and preventing current crowding at specific locations.
2Device complexity
If secondary grid connects only to one side of primary grid, then structure is simple, but current flow paths become uneven
Solution Approach 1:
The secondary grid is designed to connect to both the left and right sides of the isosceles trapezoid primary grid, creating locally optimized current collection points at both ends. This local quality enhancement ensures that current from different regions of the cell is collected more uniformly, preventing localized current crowding while maintaining overall structural simplicity.
3Productivity
If high concentration factor is used, then photoelectric conversion efficiency is improved, but current density increases causing overheating
Solution Approach 1:
The primary grid is segmented into multiple isosceles trapezoid units with secondary grids connecting at different positions. This segmentation divides the current collection into multiple parallel paths, reducing the current density in any single path. By segmenting the grid structure, the patent successfully manages the high current densities generated under high concentration factors while maintaining high photoelectric conversion efficiency.
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 design effectively distributes current, reduces resistive loss, and improves photocurrent size and conversion efficiency without increasing current crowding or resistive loss, thereby enhancing the solar cell's performance under high-concentration conditions.
Implementation Method 1
solar cells for concentrated photovoltaics normally use a gallium arsenide (GaAs)-based multi-junction solar cell
Data Source
AI summary
A high-concentration solar cell includes an epitaxial layer structure, an upper patterned electrode on the top surface, and a back electrode on the back surface. The upper patterned electrode includes a primary pattern and a secondary pattern, where the primary pattern is composed of a series of small metal isosceles trapezoids around the perimeter of the cell. The narrower base of each metal trapezoid points toward an interior of the cell. A lead soldering pad is located within each metal trapezoid for being soldered to an external conductor for carrying the solar cell current. The secondary pattern consists of thin spaced conductors that connect to the angled sides and base of each trapezoid and spread current across the top surface of the cell. The current along the angled sides of each trapezoid is well-distributed to all the spaced conductors connected to the angled sides to avoid current crowding.