Folded Light Guide with Rotated Injectors for High Solar Concentration
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Solution Overview
Problem
Concentrated photovoltaic (CPV) systems face inefficiencies in light collection and emission due to interactions with light injection elements, leading to light loss through absorption, scattering, and étendue dilution, which hinders the effective concentration and propagation of solar radiation to PV cells.
Innovation Solution
A light guide apparatus with a dimple layer and a primary light concentrator array, where the dimple layer features transversely oriented light injection elements on both sides of a strip, rotated at an angle to redirect incident light along the z-direction, and a secondary concentrator for further concentration and out-coupling of light into a PV cell.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If light injection elements are used to concentrate solar radiation, then light concentration ratio is improved, but light loss through absorption and scattering increases
Solution Approach 1:
The patent extracts the light injection elements from the traditional planar light guide structure and reconfigures them into a folded light guide geometry. This extraction allows the light to bypass problematic interaction zones while maintaining concentration capability, reducing absorption and scattering losses at injection points.
Solution Approach 2:
The patent transitions from a two-dimensional planar light guide to a three-dimensional folded structure. By introducing the folding dimension, the light path is extended without increasing the footprint, and light injection elements are positioned in spatial zones that minimize harmful interactions, thereby reducing energy loss while maintaining concentration ratio.
2Quantity of substance
If light injection elements are added to concentrate light, then light concentration is improved, but device complexity increases
Solution Approach 1:
The patent merges the light concentration function and the light guiding function into a single integrated folded structure. The light injection elements are incorporated directly into the folds of the light guide rather than being separate components, reducing overall device complexity while maintaining high light concentration capability.
Solution Approach 2:
The folded light guide structure serves multiple functions simultaneously: it concentrates light through its geometric configuration, guides light along a compact path, and positions injection elements optimally. This multi-functionality reduces the need for separate components, simplifying the overall device while achieving high concentration ratios.
3Ease of manufacture
If traditional planar light guide structure is used, then manufacturing is simpler, but light propagation efficiency is reduced due to interactions with injection elements
Solution Approach 1:
The patent segments the light guide into multiple folded sections, each with optimized light injection characteristics. This segmentation allows light to propagate through distinct zones with minimized interactions between injection elements, improving overall efficiency while maintaining manufacturability through modular construction.
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 enhances light collection and concentration efficiency, achieving over 1000× geometric concentration with optical efficiencies above 70%, while being cost-effective and easier to manufacture, and adaptable for various lighting applications.
Implementation Method 1
Depending upon the tilt angle of the light injection element, the index of refraction of the light guide, and the index of refraction of the external interface of the injection surface, radiation may be totally internally reflected from the face of the light injection element
Implementation Method 2
The light thereafter propagates generally in the z-direction towards an exit end (edge) 6 of the light guide
Data Source
AI summary
A light guide apparatus includes a light guide layer having a top surface and a bottom surface, and a transversely oriented side-end surface that forms an output aperture of the light guide, characterized by an index of refraction, n1, and further characterized by a length dimension in an intended light propagation direction towards the output aperture, where the intended light propagation direction is a z-axis direction of a Cartesian coordinate system; and a plurality of light injection elements disposed in the form of at least one linear strip in at least one of the top and bottom surfaces of the light guide layer, wherein some of the plurality of light injection elements are disposed on one lateral side of the strip and some other of the plurality of light injection elements are disposed on an opposing lateral side of the strip, further wherein each light injection element is disposed outwardly at a rotation angle Δz about the y-axis.