Solar Cell Back-Surface Flattening for Light Reflection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Crystalline silicon-based solar cells face inefficiencies in capturing light between cells in a modular setup, as incident light is not effectively reflected and utilized from the back surface, leading to reduced power generation in solar cell modules.
Innovation Solution
A crystalline silicon-based solar cell design with a textured substrate, differing conductivity-type thin-films, and patterned metal electrodes on both surfaces, including an end-portion flattening metal layer on the back surface to efficiently capture and reflect light between cells, is implemented. The end-portion flattening metal layer, formed by electroplating, moderates the texture irregularity and directs reflected light back into the solar cell, enhancing light utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If light is incident between cells in a modular solar cell setup, then light can potentially be captured and utilized, but the textured substrate causes light to be reflected away instead of being captured, reducing power generation efficiency
Solution Approach 1:
The patent applies different surface properties to different regions: the light-receiving surfaces maintain texture for light absorption, while the light-reflecting surfaces are flattened to effectively reflect incident light. This local differentiation resolves the contradiction by optimizing each surface for its specific function.
Solution Approach 2:
Instead of using textured surfaces for light reflection as might be intuitively expected, the patent inverts the approach by using flattened surfaces for reflection. This counterintuitive solution effectively redirects incident light between cells while maintaining texture on light-receiving surfaces for optimal light absorption.
2Reliability
If a back-side metal electrode is formed on the entire back surface by electroplating, then resistance is reduced and cost is reduced due to easy formation with large thickness, but light incident from the back surface cannot be effectively reflected and reused
Solution Approach 1:
The patent differentiates the back surface into two functional regions: a light-reflecting region with flattened surface for effective light reflection, and a light-receiving region with texture for light absorption. The metal electrode is selectively formed only on the light-reflecting region, optimizing both electrical conductivity and optical performance.
3Reliability
If a patterned metal electrode is formed on the light-receiving side by electroplating, then electrode resistance is reduced, but the complexity of the manufacturing process increases
Solution Approach 1:
The patent forms a metal seed layer on the transparent electrode layer before electroplating the metal electrode. This preliminary action provides a uniform base for electroplating, enabling patterned electrode formation with controlled resistance while managing manufacturing complexity through a systematic multi-step process.
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 solution significantly improves light capture and power generation in solar cell modules by efficiently reflecting and re-directing light from the back surface, increasing the module's power generation capacity.
Implementation Method 1
a texture is formed on each of the first principal surface and the second principal surface of the crystalline silicon substrate
Implementation Method 2
The metal electrode can be formed by printing an electroconductive paste etc., electroplating, or the like
Implementation Method 3
light which is incident to the cell and which is transmitted without being absorbed by a silicon substrate can be reflected at a metal electrode on the back side, and reused
Data Source
AI summary
A crystalline silicon-based solar cell includes a crystalline silicon substrate having a first principal surface, a second principal surface, and a lateral surface. On the first principal surface is arranged, in the following order, a first intrinsic silicon-based thin-film, a first conductive silicon-based thin-film, a light-receiving-side transparent electrode layer and a light-receiving-side metal electrode. On the second principal surface is arranged, in the following order, a second intrinsic silicon-based thin-film, a second conductive silicon-based thin-film, a back-side transparent electrode layer and a back-side metal electrode. The second conductive silicon-based thin-film has a conductivity-type different from that of the first conductive silicon-based thin-film. Both the first principal surface and the second principal surface are textured. Both the light-receiving-side metal electrode and the back-side metal electrode have a pattern shape. The back-side transparent electrode layer is not provided on a peripheral edge of the second principal surface.