Backside Protective Sheet for Black Appearance and NIR Transmission
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Solution Overview
Problem
Existing backside protective sheets for solar cell modules that aim for a black appearance using carbon black reduce power generation efficiency due to near-infrared light absorption, leading to increased temperature and color unevenness.
Innovation Solution
A multilayered backside protective sheet design incorporating reflective and transparent layers with perylene pigments, including two black adhesive layers and intermediate transparent layers to reflect near-infrared light and minimize color unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If carbon black is used to produce a black appearance in the backside protective sheet, then the black density is improved, but the power generation efficiency deteriorates due to near-infrared light absorption and temperature increase
Solution Approach 1:
The backside protective sheet is divided into multiple functional layers: a first layer with near-infrared reflective function, colored layers (first and second) with black appearance function that transmit near-infrared light, and an optional second layer for structural support. This segmentation allows each layer to perform its specific function without interfering with others, resolving the contradiction between black appearance and near-infrared transmission.
Solution Approach 2:
Different layers are assigned different optical properties: the first layer has high near-infrared reflectivity, while the colored layers have high visible light absorption (black appearance) but high near-infrared transmittance. This local differentiation of material properties allows the sheet to simultaneously achieve black appearance and near-infrared light transmission for maintaining power generation efficiency.
2Illumination intensity
If carbon black is used to achieve black appearance, then the black density is improved, but color unevenness increases
Solution Approach 1:
The black appearance is achieved through multiple thin colored layers rather than a single thick carbon black layer. This segmentation of the coloring function across multiple layers reduces color unevenness while maintaining sufficient black density, as each thin layer can be more uniformly applied and their combined effect provides consistent appearance.
Solution Approach 2:
The patent uses composite material structures combining different colored layers with specific optical properties. The colored layers are composed of materials that provide black appearance in the visible range while transmitting near-infrared light, creating a composite structure that achieves uniform color appearance without the manufacturing issues associated with carbon black.
3Device complexity
If a single black layer is used to reduce layer count, then device complexity is reduced, but color unevenness and black density are insufficient
Solution Approach 1:
The coloring function is segmented across multiple thin layers (first colored layer and second colored layer) rather than concentrated in a single thick layer. This segmentation improves color uniformity and black density while keeping each individual layer thin and easy to manufacture, balancing complexity with performance.
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 enhances power generation efficiency by reducing near-infrared absorption, maintains a high black density with reduced color unevenness, and minimizes pigment migration impacts.
Implementation Method 1
a first layer configured to reflect near-infrared light
Implementation Method 2
the first colored layer being configured to transmit near-infrared light
Implementation Method 3
the first colored layer being configured to transmit near-infrared light
Data Source
AI summary
A backside protective sheet for solar cell modules includes a first layer configured to reflect near-infrared light, a first colored layer arranged closer to a light-receiving surface than the first layer and configured to transmit near-infrared light, and a second colored layer arranged closer to the light-receiving surface than the first colored layer and configured to transmit near-infrared light.