Solar Cell Electrode with Triangular and Trapezoidal Finger Cross Sections

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Solution Overview

Problem

Existing solar cell electrode structures, while improving output by varying finger widths, face challenges in further increasing efficiency and reliability, particularly in reducing shading loss and optimizing light utilization.

Innovation Solution

The solar cell features a frontside electrode with bus bar and finger portions, where the first end portion has a triangular cross-section and the second end portion has a trapezoidal cross-section, with a constant height that gradually decreases from the bus bar, formed using a screen printing method, to reduce shading loss and enhance light usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the width of finger portions is increased to reduce shading loss, then light utilization improves, but the structural strength and stress distribution may be compromised

Engineering Contradiction:

Improvepower generation outputVSAvoidelectrode structural strength

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The finger portion is designed with varying cross-sectional shapes along its length: a triangular cross-section at the first end portion for optimal light transmission and reduced shading, and a trapezoidal cross-section at the second end portion for enhanced structural strength and stress distribution. This local differentiation allows each region to perform its specific function optimally without compromising overall performance.

Inventive Principle:

Principle #3Local quality

2Productivity

If the finger portion width is optimized for light transmission, then shading loss is reduced, but the connection reliability with bus bar may deteriorate

Engineering Contradiction:

Improvelight utilization efficiencyVSAvoidelectrode connection reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The finger portion employs different cross-sectional geometries at different locations: the triangular cross-section at the first end optimizes light transmission and reduces shading, while the trapezoidal cross-section at the second end enhances mechanical connection reliability with the bus bar through improved stress distribution and contact area.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If constant height is maintained across the finger portion, then manufacturing is simplified, but stress distribution under load becomes suboptimal

Engineering Contradiction:

Improveelectrode fabrication simplicityVSAvoidstress distribution performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The finger portion is designed with constant height in the central region for manufacturing simplicity, while the cross-sectional shape varies at the ends (triangular at first end, trapezoidal at second end) to optimize both light transmission and stress distribution. This localized variation achieves performance optimization without significantly complicating the manufacturing process.

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP2738816B1Solar cell, solar cell module, and method for producing solar cell

Publication Date: 2019.09.18 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

Figure 1(a)~2(c)
Figure 3~5
Figure 6

AI summary

A solar cell (1) includes bus bar portions (3b and 4b) and finger portions (3a and 4a). Each of the finger portions (3a and 4a) has a first end portion that extends in a longitudinal direction of the finger portion (3a or 4a), and a second end portion that is connected to the bus bar portion (3b or 4b). The first end portion has a triangular cross section, and the second end portion has a trapezoidal cross section.