Bifacial Solar Cell Back Sheet with Segmented Reflective and Absorptive Layers
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Solution Overview
Problem
Conventional solar cell modules face inefficiencies in light absorption and energy conversion due to the limitations of existing back sheet materials, which fail to effectively reflect and absorb light across the entire visible and infrared spectrum, leading to reduced solar cell efficiency and output.
Innovation Solution
A back sheet comprising a base layer and multiple sheet layers with varying transmittance and reflectance properties, including a white first sheet layer with high reflectance and a black second sheet layer with perylene-based organic pigment, strategically positioned to enhance light absorption and reflection across the 300 nm to 1200 nm wavelength range, improving energy conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional back sheet with uniform structure is used, then the manufacturing process is simple, but the light absorption efficiency is insufficient
Solution Approach 1:
The back sheet is divided into multiple functional layers: a base layer, a first sheet layer with white pigment for light scattering, and a second sheet layer with black pigment for light absorption. This segmentation allows each layer to perform its specific function, collectively improving light absorption efficiency while maintaining manufacturing feasibility through layer-by-layer construction.
Solution Approach 2:
Different regions of the back sheet are assigned different optical properties: the first sheet layer contains white pigment for scattering light in the visible range, while the second sheet layer contains black pigment for absorbing light in the infrared range. This local differentiation of material properties enables optimized light management across different wavelength ranges.
2Productivity
If a single-layer back sheet is used, then the manufacturing cost is low, but the energy conversion efficiency is reduced
Solution Approach 1:
The back sheet employs a composite structure combining materials with different optical characteristics: a base layer provides structural support, the first sheet layer uses white pigment particles for light scattering, and the second sheet layer uses black pigment particles for light absorption. This composite material approach enables enhanced energy conversion efficiency by capturing light across multiple wavelength ranges.
3Productivity
If the back sheet uses uniform transmittance, then the material selection is simple, but the short-circuit current is limited
Solution Approach 1:
The back sheet implements spatially varying transmittance characteristics: the first sheet layer with white pigment provides high scattering and low transmittance in the visible range, while the second sheet layer with black pigment provides selective absorption and different transmittance in the infrared range. This local quality differentiation maximizes short-circuit current by optimizing light interaction at different positions and wavelengths.
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 proposed back sheet design significantly increases the short-circuit current and maximum output of solar cell modules by ensuring light is absorbed in both the front and back surfaces, enhancing energy conversion efficiency and output compared to traditional designs.
Implementation Method 1
a white first sheet layer with high reflectance
Implementation Method 2
a black second sheet layer with perylene-based organic pigment, strategically positioned to enhance light absorption and reflection across the 300 nm to 1200 nm wavelength range
Implementation Method 3
A solar cell, to which a principle of the solar power generation is applied, is a semiconductor device converting solar light into electric energy
Data Source
AI summary
Discussed is a solar cell module including a plurality of bi-facial solar cells having a front surface and a back surface, a light transmission protection part positioned on the front surfaces of the plurality of bi-facial solar cells, a front protection part positioned between the light transmission protection part and the front surfaces of the plurality of bi-facial solar cells, a back sheet positioned on the back surfaces of the plurality of bi-facial solar cells, wherein the back sheet includes a first area overlapping the plurality of bi-facial solar cells, and a second area being a remaining portion except the first area and a back protection part positioned between the back sheet and the back surfaces of the plurality of bi-facial solar cells, wherein the back sheet includes a base layer, a first sheet layer, and a second sheet layer.