Solar mirrors having improved properties
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Solar mirrors used in concentrated solar thermal power and photovoltaic systems face challenges in maximizing solar light reflection and extending their usable life due to issues with reflectance and thermal stability, leading to inefficiencies and frequent replacements.
Innovation Solution
A solar reflective coating is developed with a multilayer structure, including sublayers separated by parting layers to inhibit crystal growth and enhance optical stability, and an encapsulated coating stack with a lead-free corrosion inhibitor to protect the reflective coating from environmental degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-layer reflective coating is used to simplify the structure, then the manufacturing process is easier and device complexity is reduced, but the thermal stability and optical performance deteriorate due to uncontrolled crystal growth
Solution Approach 1:
The reflective coating is divided into multiple sublayers (e.g., Ag, Al, or other metallic layers) separated by parting layers (e.g., TiO2, SiO2, or other dielectric materials). This segmentation prevents continuous crystal growth across the entire coating thickness while maintaining high reflectivity, thereby improving thermal stability without significantly increasing manufacturing complexity
Solution Approach 2:
The coating structure uses composite materials combining metallic reflective layers with dielectric parting layers. This composite structure leverages the high reflectivity of metals and the thermal stability of dielectrics to achieve both optical performance and thermal resistance
2Device complexity
If the reflective coating is exposed directly to the environment to reduce device complexity, then manufacturing is simpler, but the durability and usable life decrease due to environmental degradation
Solution Approach 1:
The reflective coating stack is nested within an encapsulant matrix that fully encapsulates the coating. This nested structure protects the sensitive metallic layers from environmental factors such as moisture, oxygen, and pollutants, significantly improving durability and usable life while adding only one manufacturing step
Solution Approach 2:
A thin film encapsulant layer is applied over the reflective coating to provide environmental protection. This thin film barrier prevents direct contact between the coating and harsh environmental conditions, enhancing reliability without substantially increasing device complexity
3Reliability
If lead-based corrosion inhibitors are used to improve protection against environmental degradation, then reliability improves, but harmful factors increase due to lead toxicity
Solution Approach 1:
The encapsulant composition is modified by replacing lead-based corrosion inhibitors with lead-free alternatives such as calcium carbonate, magnesium hydroxide, or other environmentally friendly additives. This parameter change maintains the corrosion protection function while eliminating toxic effects
Solution Approach 2:
The formulation transitions from using toxic lead compounds to employing benign materials that provide equivalent or superior protection. The harmful lead-based approach is converted into a beneficial lead-free solution that maintains reliability while eliminating environmental and health hazards
4Productivity
If high reflectance is prioritized to maximize solar light reflection, then energy efficiency improves, but thermal stability deteriorates due to increased light absorption and heat generation
Solution Approach 1:
The coating is segmented into multiple thin sublayers rather than a single thick layer. This segmentation reduces the overall absorption path for incident light, maintaining high reflectance while distributing thermal stress across multiple interfaces, thereby improving thermal stability
Solution Approach 2:
The composite structure combines highly reflective metallic layers with thermally stable dielectric parting layers. This composition optimizes optical performance by maximizing reflection from metal layers while the dielectric layers provide thermal stability and reduce heat accumulation
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 the thermal stability and reflectance of solar mirrors, reducing specular-excluded reflectance and extending the usable life of the mirrors while maintaining high reflectivity, thus enhancing the efficiency and durability of solar energy concentration systems.
Implementation Method 1
sublayers separated by parting layers to inhibit crystal growth and enhance optical stability
Implementation Method 2
solar mirrors reflect and concentrate solar light onto a receiving surface on the tower
Implementation Method 3
an encapsulated coating stack with a lead-free corrosion inhibitor to protect the reflective coating from environmental degradation
Data Source
Figure 1~3
Figure 2~4
Figure 5~6
AI summary
An article for reflecting solar energy, comprising a coating stack comprising solar reflecting films and metal oxide films, the coating stack applied on a major surface of a glass substrate; and a protective overcoat; and a polymer encapsulant over outer wall surfaces of the coating stack, the outer surface of the protective overcoat and over peripheral edges of the coated article, the encapsulant comprising a base layer, a top layer and metallic corrosion-inhibitive material in the base layer.