Solar mirrors and methods of making solar mirrors having improved properties
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Solution Overview
Problem
Solar mirrors in existing technologies face challenges in maximizing solar light reflection and extending their usable life, particularly in concentrated solar thermal power and photovoltaic applications, where frequent replacement due to reduced reflectance and stability issues is a concern.
Innovation Solution
The development of a solar mirror with a coating stack comprising multiple metal solar reflecting films separated by parting layers and a polymer encapsulant, including a base layer with metallic zinc flakes, applied on a glass substrate to enhance optical stability and thermal resistance, thereby improving reflectance and longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single reflective coating is applied to the substrate, then the manufacturing process is simple, but the reflectance and thermal stability are insufficient
Solution Approach 1:
The reflective coating is divided into multiple discrete layers (first reflective layer, second reflective layer) separated by a parting layer. This segmentation allows each layer to contribute to reflectance while the parting layer provides thermal isolation, resolving the contradiction between simple manufacturing and improved stability by creating a modular structure that can be applied using standard vacuum deposition techniques.
Solution Approach 2:
The coating system uses composite material structure combining different reflective materials (such as silver and aluminum) with a parting layer material. This composite approach enables the system to achieve both high reflectance from the metallic layers and thermal stability from the parting layer, overcoming the limitations of single-material coatings.
2Adaptability or versatility
If the mirror is exposed to high temperature conditions, then the operational flexibility is improved, but the reflectance decreases and service life is reduced
Solution Approach 1:
The parting layer acts as an intermediary between the two reflective layers, providing thermal isolation that prevents heat from degrading the reflective properties. This intermediary layer allows the mirror to operate at higher temperatures while maintaining reflectance, as the parting layer absorbs and distributes thermal stress without allowing it to compromise the reflective surfaces.
Solution Approach 2:
The invention changes the thermal parameters of the coating system by introducing the parting layer with specific thermal properties. This parameter change enables the coating system to withstand higher temperatures without degradation, transforming the system's thermal response from vulnerable to resilient while maintaining optical performance.
3Reliability
If frequent replacement of mirrors is performed, then the system can maintain optimal performance, but the productivity and cost increase
Solution Approach 1:
The multi-layer coating structure with parting layer is designed in advance to prevent reflectance degradation before it occurs. By building in thermal protection and reflectance stability from the outset, the mirror maintains optimal performance for extended periods, eliminating the need for frequent replacements and maintaining high system availability without compromising performance optimization.
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 increases the specular reflectance and thermal stability of solar mirrors, reducing non-specular reflectance and extending their service life, even under high-temperature conditions, while minimizing the need for frequent replacements.
Implementation Method 1
a base layer with metallic zinc flakes... significantly increases the specular reflectance
Implementation Method 2
a polymer encapsulant... improving reflectance and longevity... thermal stability
Data Source
AI summary
An article for reflecting solar energy includes a coating stack having solar reflecting films and metal oxide films, the coating stack applied on a major surface of a glass substrate, and a protective overcoat comprising a first and a second surface, wherein the first surface of the protective overcoat is disposed toward the solar reflective films and metal oxide films; and a polymer encapsulant over outer wall surfaces of the coating stack, the second surface of the protective overcoat and over peripheral edges of the coated article, the encapsulant having a base layer, a top layer and metallic corrosion-inhibitive material in the base layer.