Reflective Secondary Optic for Solar Concentrator Thermal Management

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing secondary optics in concentrator photovoltaics face issues such as light absorption leading to heating and destruction, reflections due to refractive index differences, high production costs, and difficulties in assembly and heat dissipation, particularly in highly concentrating systems.

Innovation Solution

The development of reflective and refractive secondary optics with a projection surrounding the reflector, made from materials like aluminum or aluminum alloys, featuring a highly reflective coating and an optically transparent cavity filled with materials of higher refractive index, along with a fastening element for secure attachment to a semiconductor element or chip carrier, enhancing reflection, thermal management, and assembly efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If refractive secondary optics are used to focus light onto solar cells, then light concentration is achieved, but light absorption by the optics material causes heating and potential destruction

Engineering Contradiction:

Improvelight concentration efficiencyVSAvoidoptics temperature

Core Design Contradiction:

Use of energy by moving objectVSTemperature

Solution Approach 1:

The patent replaces refractive optics (which absorb light and heat up) with reflective optics made of highly reflective metal surfaces. The reflective principle redirects light without significant absorption, eliminating the heating problem while maintaining light concentration functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses composite structures combining highly reflective metal surfaces with protective coatings and mounting materials to create secondary optics that reflect light efficiently while managing thermal loads through the composite material properties.

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If refractive secondary optics are used, then light concentration is achieved, but reflections occur at the entrance surface due to refractive index differences

Engineering Contradiction:

Improvelight concentration efficiencyVSAvoidreflection loss

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The patent substitutes refractive surfaces with reflective surfaces. Reflection from metal surfaces can achieve >95% reflectivity, whereas refractive surfaces suffer from Fresnel reflections at air-material interfaces. This substitution eliminates the refractive index mismatch problem.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If simple reflective secondary optics are used, then production costs are reduced, but assembly and heat dissipation become difficult

Engineering Contradiction:

Improveproduction costVSAvoidassembly ease

Core Design Contradiction:

Ease of manufactureVSEase of operation

Solution Approach 1:

The patent divides the secondary optics into modular segments or standardized components that can be independently manufactured and then assembled. This segmentation maintains manufacturing simplicity while enabling systematic assembly procedures and improved heat dissipation through distributed structures.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent designs universal mounting interfaces and standardized connection elements that work across different optical configurations. This universality simplifies assembly procedures while allowing the same basic structure to serve both optical and thermal management functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Loss of energy

If reflective layers are applied before forming, then reflection is increased, but the sheets become difficult to form and assemble

Engineering Contradiction:

Improvereflection efficiencyVSAvoidforming difficulty

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The patent applies the reflective coating after the forming process rather than before. This sequence allows the metal sheet to be formed into the desired optical shape first, then coated with the reflective layer. This preliminary action ordering resolves the conflict between formability and reflectivity.

Inventive Principle:

Principle #10Preliminary action

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

This design improves light absorption efficiency, reduces thermal stress, lowers production costs, and facilitates easier assembly, while maintaining long-term stability and resistance to corrosion, effectively addressing the limitations of previous secondary optics in concentrator photovoltaic systems.

Implementation Method 1

the reflector (3) essentially consists of a metallic base material that has a particularly high reflection of light on the inside

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

an optically transparent cavity (7) filled with materials of higher refractive index

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 3

reduces thermal stress

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 4

the cavity (7) filled with materials of higher refractive index

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 5

light absorption efficiency

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentEP2235756B1Reflective secondary optic, semiconductor assembly and method for the fabrication thereof

Publication Date: 2018.08.22 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

Figure 1a~1b
Figure 2a~2c
Figure 3a~3b

AI summary

The present invention relates to a reflective and/or refractive secondary optics for focusing sun light onto semiconductor components, wherein according to the invention the secondary optics is characterized by a projection that is arranged around the base body forming the secondary optics. The present invention further relates to a semiconductor assembly comprising the secondary optics according to the invention, and to a method for producing said semiconductor assembly. In particular, said semiconductor assembly is a focusing solar cell module.