Micro-Lens Array Design for Tracking-Free Solar Concentration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current solar technologies face limitations in photon conversion efficiency due to quantum-physics and optical constraints, leading to reduced power generation, and conventional concentrated photovoltaics are large, heavy, and restricted to specific geographical locations, while solar thermal systems experience inefficiencies in energy production and heat loss.
Innovation Solution
The development of micro-lenses using nano-scale fabrication methods and zero contrast grating designs for improved angular efficiency, reduced heat loss, and elimination of tracking systems in solar assemblies, enabling more compact and flexible solar cell designs that can operate under various climatic conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional concentrated photovoltaics use large lenses or curved mirrors to focus sunlight, then photon conversion efficiency is improved, but system size and weight increase significantly
Solution Approach 1:
The patent divides the large concentrating lens into multiple small microlenses arranged in an array. Each microlens focuses light onto a corresponding small photovoltaic cell. This segmentation maintains the light concentration function while dramatically reducing the overall size and weight of the optical components and supporting structure.
Solution Approach 2:
The patent transitions from using large two-dimensional lens surfaces to a three-dimensional array of numerous small microlenses. This dimensional reorganization allows the system to maintain total light-gathering area while reducing the footprint and weight of individual components and their mounting structures.
2Productivity
If conventional CPV systems use tracking mechanisms to follow the sun, then power generation is improved, but device complexity and cost increase
Solution Approach 1:
Each microlens in the array is designed with specific optical properties optimized for its position and orientation. The microlenses have varying focal lengths and optical characteristics tailored to their local requirements, allowing the system to maintain high efficiency across different sun positions without mechanical tracking.
Solution Approach 2:
The patent varies the focal length and optical parameters of individual microlenses within the array to compensate for angular changes in incident sunlight. By changing the optical parameters of the microlens array rather than the physical orientation of the system, tracking is eliminated while maintaining power generation efficiency.
3Productivity
If solar thermal systems use large collector areas to produce energy, then energy production is improved, but heat loss increases
Solution Approach 1:
The patent segments the solar thermal collector into multiple small focal points, each created by individual microlenses. This segmentation allows for more efficient heat concentration at each focal point, reducing the overall collector area needed and thereby reducing total heat loss to the environment.
Solution Approach 2:
The patent employs selective surface coatings and composite material structures at the focal points to enhance heat absorption and reduce radiative heat loss. These composite material solutions improve the thermal efficiency of each focal point, allowing smaller collector areas with reduced overall heat loss.
4Productivity
If conventional solar technologies are optimized for direct normal incident radiation, then conversion efficiency is improved, but adaptability to diffuse radiation and various climatic conditions deteriorates
Solution Approach 1:
The microlens array design provides multiple functions: it concentrates direct sunlight efficiently while also being effective with diffuse radiation. The system can operate in various climatic conditions including cloudy days and different geographical locations, making it a universal solution that maintains adaptability while preserving conversion efficiency.
Solution Approach 2:
The patent creates a dynamic optical system where light can enter the microlens array from various angles and still be effectively focused. This dynamic optical design allows the system to adapt to changing radiation conditions and climatic variations without mechanical adjustment, maintaining efficiency across diverse environments.
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 solution enhances angular efficiency, reduces heat loss, and allows solar systems to function effectively in diverse conditions, making them more compact, lightweight, and cost-competitive, expanding their application beyond traditional sun belt regions.
Implementation Method 1
The micro-lens is configured to receive radiation energy and focus the radiation energy at a focusing region
Implementation Method 2
photovoltaic cells that generate power from sunlight
Data Source
AI summary
A design for a micro-lens (i.e., a lens on the scale of micrometers) incorporates existing nanofabrication techniques and can be incorporated into High Concentrating Photovoltaic (HCPV), solar thermal collectors, and traditional flat PV systems. Using the theory of wave optics, the design is able to achieve a high numerical aperture, i.e., it can receive light over a wider range of angles. The design also reduces the distance the focal point shifts as the light source shifts; this eliminates the need for a tracking system in CPV and PV applications. Reducing the lens size also facilitates smaller, lightweight CPV systems, which makes CPV attractive for additional applications. Finally, these concentrators reduce the exchanging area of a typical flat solar thermal system where heat is received, which improves the overall system's efficiency and allows its use also during rigid winter time.