Embedded Cavity Reflector Structure for Solar Backsheet Light Redirection
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Solution Overview
Problem
Conventional solar panel backsheet structures suffer from significant light reflection and absorption losses, leading to reduced energy efficiency due to isotropic reflectivity and internal light trapping, particularly in white and black backsheet configurations.
Innovation Solution
An optical structure with integrated, embedded cavity optics is introduced, comprising a flat, planar base element and a patterned carrier element with surface relief profiles, allowing for light redirection and reflection at angles exceeding the total internal reflection limit, thereby enhancing light capture and distribution within the solar panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional white backsheet is used, then light reflection is improved (about 80-90% reflectivity), but internal light trapping causes energy loss (more than 60% total loss including reflection out of panel)
Solution Approach 1:
The optical structure embeds cavity optics within the backsheet layer itself, creating nested functional elements where microlens arrays and reflective cavities are integrated into the backsheet structure. This nesting allows the backsheet to simultaneously provide structural support and advanced optical functionality, resolving the contradiction by enabling light redirection while maintaining high reflectivity without additional external components.
Solution Approach 2:
The invention transitions from conventional planar backsheet surfaces to three-dimensional cavity structures with microlens arrays. By adding vertical dimensionality through embedded cavities and lens profiles, the system redirects light at angles exceeding total internal reflection limits, converting the backsheet from a simple reflective surface to a multi-functional optical element that reduces energy loss while maintaining high illumination intensity.
2Illumination intensity
If a black backsheet is used, then light absorption is improved (about 95% absorption), but solar energy is lost without energy gain
Solution Approach 1:
The invention converts the harmful effect of light absorption by black backsheets into a beneficial function by embedding cavity optics that redirect absorbed and reflected light at angles exceeding total internal reflection. The black backsheet's high absorption property is transformed from an energy loss mechanism into a light-trapping feature that increases the optical path length and enhances energy capture by the photovoltaic cells.
Solution Approach 2:
The invention changes the optical parameters of the backsheet by integrating cavity structures with specific geometries and refractive indices. This parameter modification allows the backsheet to transition from a passive absorbing surface to an active light-redirection element, enabling black backsheets to achieve both high absorption and reduced energy loss simultaneously through controlled light path manipulation.
3Ease of manufacture
If conventional adhesive lamination is used, then manufacturing is simplified, but optical transparency and light distribution are limited
Solution Approach 1:
The optical structure integrates multiple functions into a single backsheet component: structural support, adhesive bonding, light reflection, light redirection, and optical transparency. By combining these functions into one multi-functional element, the invention maintains manufacturing simplicity while dramatically improving light distribution through embedded cavity optics that conventional single-function adhesives cannot provide.
4Ease of manufacture
If passive surface area with Lambertian reflectivity is used, then manufacturing is simplified, but energy losses occur due to light reflection and shading
Solution Approach 1:
The invention applies different optical properties to different regions of the backsheet through embedded cavity patterns. Specific areas contain microlens arrays and reflective cavities with tailored geometries that redirect light locally at angles exceeding total internal reflection, while other regions maintain simplified structures. This local differentiation reduces energy losses in critical areas without compromising overall manufacturing simplicity.
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 optical structure increases solar panel efficiency by 4.0-5.5% for white backsheets and 5.0-6.5% for black backsheets, optimizing material costs and spacing area, with gains of 25 W-35 W in PV modules, and achieving better light capture and distribution compared to conventional solutions.
Implementation Method 1
allowing for light redirection and reflection at angles exceeding the total internal reflection limit
Implementation Method 2
reflects about 44% of light incident (1) onto a solar panel
Implementation Method 3
a significant amount of energy is lost due to light reflection out of the panel
Data Source
AI summary
An thin and flat reflector solution is provided including an entirely flat, planar base element; and an at least one flat, planar carrier element provided with cavities arranged into an at least one pattern, wherein the carrier element(s) and optionally the base element are substantially optically transparent, wherein the at least one carrier element is laminated together with a base element such, that an at least one embedded, optically functional cavity pattern is established at an interface between the elements, and wherein the optical structure is rendered optically functional by adjusting cavity profiles within each the embedded pat-tern and/or within each the carrier element, wherein an optical function is selected from light reflection, light refraction and light redirection.