Photovoltaic encapsulant system with glass spheres for enhanced light reflection and environmental protection

Abstract

A photovoltaic encapsulant system incorporates glass spheres within a polymer matrix to address light losses, water and oxygen diffusion, and brittleness in photovoltaic modules. Glass spheres ranging from 4 / 1000 to 25 / 1000 inch in diameter create refractive index interfaces that redirect reflected light back toward photovoltaic cells for additional energy conversion while establishing tortuous diffusion pathways that impede infiltration of degrading agents. The encapsulant exhibits light absorption of 6% or less compared to 10-11% for conventional glass fiber composites. The flexible system eliminates brittle glass top sheets, reducing the 5-10% failure rate from cracking during manufacturing and installation while providing enhanced optical efficiency and extended operational lifetime.

Description

PHOTOVOLTAIC ENCAPSULANT SYSTEM WITH GLASS SPHERES FOR ENHANCED LIGHT REFLECTION AND ENVIRONMENTAL PROTECTIONCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of United States Provisional Patent Application 63 / 739,206 filed on December 27, 2024, which is hereby incorporated by reference in its entirety.FIELD OF THE INVENTION

[0002] The present invention relates to encapsulant materials for photovoltaic devices and modules. More particularly, the present invention relates to encapsulant systems for enhancing the optical efficiency and environmental durability of photovoltaic modules while providing mechanical protection to the underlying photovoltaic cells.BACKGROUND OF THE INVENTION

[0003] Photovoltaic energy systems have become increasingly important as alternatives to traditional fossil fuel and nuclear power sources. However, conventional photovoltaic modules suffer from several significant efficiency and durability limitations that reduce their effectiveness and operational lifetime.

[0004] A primary problem with existing photovoltaic panels is that they lose substantial amounts of their potential energy through light reflection. When incident light strikes a photovoltaic cell, significant portion of the light that is not immediately absorbed by the cell is reflected back out of the panel and lost, rather than being recaptured for energy conversion. This reflected light represents wasted energy that could otherwise contribute to power generation.

[0005] Additionally, conventional photovoltaic modules experience degradation over time due to the diffusion of water and oxygen through the edge of their protective coatings and into the photovoltaic cells. This infiltration of oxidizing agents damages the electronic components and reduces the operational lifetime of the solar panels, affecting virtually every solar cell chemistry currently in use.

[0006] Current protective coating solutions that incorporate glass fibers create additional problems. These glass fiber composite coatings, such as those combining glass mat with EVA adhesive and ETFE (ethylene tetrafluoroethylene) plastic outer layers for flexible cells, and for EVA adhered rigid glass top sheet positioned over the photovoltaic cell are necessarily thick and absorb approximately 10-11% of the total incident light. This significant light absorption directly reduces the efficiency of the photovoltaic system.

[0007] Furthermore, many existing photovoltaic modules incorporate rigid glass top sheets to protect the fragile solar cel 1 s beneath. These glass layers are prone to cracking and shattering during manufacturing, installation, or from environmental impacts such as hail. Industry data indicates that 5-10% of all solar cell modules experience breakage due to cracking or shattering at some point during manufacturing or installation, representing substantial economic losses.

[0008] There exists a need in the art for a photovoltaic module encapsulant that can reduce light losses, improve durability against water and oxygen diffusion, minimize light absorption, and eliminate the brittleness problems associated with conventional glass protective layers.SUMMARY OF THE INVENTION

[0009] In accordance with embodiments of the invention, the problems of light losses, water and oxygen diffusion, and brittleness in photovoltaic modules are solved by incorporating glass spheres within an encapsulant material to create multiple light-redirecting interfaces while establishing tortuous diffusion pathways that enhance both optical efficiency and barrier properties.

[0010] This inventive approach fundamentally changes how reflected light is managed in photovoltaic systems. Rather than allowing reflected light from the solar cell surface to escape from the module as waste energy, the glass sphere encapsulant creates refractive index differences at the sphere-polymer interfaces that redirect this reflected light back toward the photovoltaic cell for additional energy conversion opportunities.

[0011] The glass spheres preferably range in size from approximately 4 / 1000 to 25 / 1000 inch in diameter in accordance with embodiments and are advantageously arranged in close-packed configurations using multiple sphere sizes to maximize packing density. Solid glass spheres are preferred over hollow spheres to optimize refractive index matching with the encapsulant material. The spheres may be manufactured through processes such as melting and spraying droplets to achieve nearly perfectly spherical shapes.

[0012] The encapsulant material in embodiments comprises various optically transparent UV resistant polymers, with silicone materials such as DOWSIL 6326 being particularly preferred for their excellent light transmission properties. Alternative materials such as optical urethanes or other silicone encapsulants may also be employed depending on the specific application requirements.

[0013] Beyond the optical benefits, the close-packed arrangement of glass spheres creates highly tortuous diffusion pathways that significantly impede the infiltration of water and oxygen through the atmosphere exposed edges into the photovoltaic cells. This tortuous path, combinedwith the reduced volume of organic polymer material, substantially enhances the barrier properties compared to conventional encapsulated systems.

[0014] The resulting encapsulant structure exhibits dramatically reduced light absorption compared to prior art systems - typically 6% or less versus the 10-11% absorption characteristic of conventional glass fiber composite coatings. This improvement directly translates to enhanced photovoltaic efficiency.

[0015] The invention also eliminates the need for rigid glass top sheets that are prone to cracking and shattering during manufacturing, installation, or environmental impacts such as hail. The flexible nature of the glass sphere encapsulant provides impact resistance while maintaining optical performance.

[0016] The encapsulant may be applied in various forms, including as a pre-formed tape or as a flowable coating that can be applied directly to photovoltaic modules. Manufacturing involves mixing the glass spheres with the encapsulant material using standard mixing methods, followed by degassing procedures to eliminate trapped air.

[0017] In particularly advantageous embodiments, the encapsulant may optionally incorporate glass fiber materials to provide additional structural reinforcement while maintaining the primary optical and barrier benefits of the glass sphere technology.BRIEF DESCRIPTION OF THE FIGURES

[0018] Figure 1 is a cross-sectional view of a photovoltaic module incorporating the glass sphere encapsulant system in accordance with an embodiment of the invention, showing photovoltaic cell, glass sphere encapsulant layer with glass spheres (distributed throughout polymer matrix, bus bars, top screen, and substrate layer, with light rays illustrating incident light and reflected light being redirected back to the cell.

[0019] Figure 2 depicts a magnified view of the light reflection mechanism in accordance with an embodiment of the invention, showing glass spheres at the photovoltaic cell interface with light ray paths illustrating incident light entering the encapsulant, light reaching the photovoltaic cell, reflected light from the cell intersecting sphere-polymer interfaces at reflection points, and redirected light returning to the photovoltaic cell for additional conversion.

[0020] Figure 3 is a perspective cutout view illustrating prior art photovoltaic module limitations, depicting glass fiber composite coating with plastic outer layer, light losses through absorption via light channels, straight diffusion pathways for water / oxygen, and brittle cracking points, further depicting how light enters through the coatings to interact with solar material, with some light reflected from the solar materials surface back outside of the system.

[0021] Figure 4 is a cross-sectional view of multiple comparative examples of glass sphere size distribution and close-packing arrangements in accordance with an embodiment of the invention, showing normal spheres, multimodal spheres, large spheres, and glass sphere encapsulant layer with variations in packing density ranging from approximately 4 / 1000 to 25 / 1000 inch in diameter (80-250 um).

[0022] Figure 5a is a cross-sectional view illustrating diffusion pathways in prior art encapsulant systems, showing direct, unimpeded diffusion routes for light and water / oxygen through continuous polymer layers with light distribution paths and light channels.

[0023] Figure 5b is a cross-sectional view illustrating tortuous diffusion pathways created by close-packed glass sphere arrangements in accordance with an embodiment of the invention, showing highly circuitous routes for water / oxygen diffusion through the atmosphere exposed edge, and light channels with reduced polymer volume between spheres and light distribution paths.

[0024] Figure 6a is a perspective view showing pre-formed tape application method in accordance with an embodiment of the invention, illustrating the old solar panel, roll of inventive tape, and top layer with the glass sphere encapsulant system applied as a pre-formed tape to photovoltaic modules with uniform glass sphere distribution throughout the tape structure with a contact surface having a substantially uniform structure with spheres placed proximally to the solar cell, and curved structure.

[0025] Figure 6b is a perspective view showing flowable coating application method in accordance with an embodiment of the invention, illustrating flowable coating being applied via nozzle and top layer, with the glass sphere encapsulant system being applied as a flowable coating by brushing or spraying directly onto photovoltaic modules, with lamination process using heated platens.

[0026] Figure 7a is a perspective view showing an application via stamping in accordance with an exemplary embodiment of the invention, illustrating heat press, silicon, old solar panel, and top layer, wherein a stamping plate coated with a silicone hump akin to a paint stamping system is used to eliminate intruded gas bubbles.

[0027] Figure 7b is a view showing an exemplary application configuration in accordance with the invention, illustrating top layer and internal spheres, demonstrating the potential for flexible photovoltaic applications, retrofit applications over existing modules, high-voltage system configurations, and optional glass fiber reinforcement integration.

[0028] Figure 8 is a detailed view showing comprehensive performance improvements achieved by the glass sphere encapsulant system in accordance with an embodiment of the invention,illustrating light, glass spheres, reflection points, and photovoltaic cell, demonstrating both the light reflection mechanism with quantified light absorption reduction and the elimination of brittle failure modes with enhanced barrier properties against water and oxygen diffusion through tortuous pathways.

[0029] Figure 9 is a performance benefits comparison chart quantifying the comprehensive improvements of the inventive glass sphere encapsulant system over conventional approaches, showing new invention table versus prior art with comparative data for light absorption (6% vs 10-11%), failure rates (cracking: 0% vs 5-10%), efficiency improvements from light redirection, and extended operational lifetime from reduced diffusion, demonstrating the inventive solution versus conventional methods.DETAILED DESCRIPTION

[0030] In accordance with an embodiment of the invention, a photovoltaic encapsulant system incorporating glass spheres within a polymer matrix fundamentally addresses the problems of light losses, water and oxygen diffusion life, and brittleness that have long plagued conventional photovoltaic modules. Rather than allowing reflected light from photovoltaic cells to escape as waste energy, embodiments of the present invention redirect this reflected light back toward the photovoltaic cell through strategically positioned refractive index interfaces created by the glass sphere-polymer boundaries. Simultaneously, the close-packed arrangement of glass spheres creates highly tortuous diffusion pathways that significantly impede the infiltration of degrading agents while reducing the volume of organic polymer material that can absorb incident light.

[0031] The following detailed description illustrates various embodiments of the invention with reference to the accompanying drawings. Additional figures demonstrate alternative configurations and manufacturing implementations of the inventive concept.

[0032] In accordance with embodiments of the invention, Figure 1 illustrates a cross-sectional view of photovoltaic module 200 incorporating the glass sphere encapsulant system, demonstrating the fundamental structure and light interaction mechanisms that enable the inventive solution. As shown in Figure 1, photovoltaic ceil 201 forms the central active component of the module, positioned to receive incident solar radiation. Glass sphere encapsulant layer 203 is disposed over the light-incident side of photovoltaic cell 201, with glass spheres 101 distributed uniformly throughout the encapsulant matrix. Bus bars 207a and 207b provide electrical connections to the photovoltaic ceil 201, while substrate layer 205 provides structural support for the entire assembly. Top screen 206 provides additional structural integrity. The figure demonstrates how incident light rays 210 enter the encapsulant system and howreflected light from the photovoltaic cell surface encounters the glass sphere-polymer interfaces, creating the refractive index differences that redirect the reflected light back toward the photovoltaic cell for additional energy conversion opportunities. This configuration eliminates the need for rigid glass top sheets while providing the optical efficiency enhancements and environmental protection that characterize the inventive approach.

[0033] In accordance with embodiments of the invention, Figure 2 provides a magnified detailed view of the light reflection mechanism that represents the core optical innovation of the glass sphere encapsulant system. The figure illustrates glass spheres 101 positioned at the interface with photovoltaic cell 201, showing the specific light ray paths that demonstrate how the inventive system captures and redirects reflected light. Incident light rays are shown entering the encapsulant system and reaching the photovoltaic cell surface, where a portion of the light is absorbed for energy conversion while the remainder is reflected back through the encapsulant. The critical inventive feature illustrated is how this reflected light encounters the curved surfaces of glass spheres 101, creating refractive index interfaces at reflection points 300 that redirect a portion of the reflected light back toward photovoltaic cell 201. Multiple light ray paths demonstrate the various angles at which reflected light can be captured and returned to the photovoltaic cell, illustrating the light-trapping effect that enhances overall photovoltaic efficiency. The spherical geometry of glass spheres 101 is shown to be critical for creating the multiple reflection opportunities that distinguish this invention from conventional encapsulant approaches.

[0034] In accordance with embodiments of the invention, Figure 3 provides a comparative cross-sectional view illustrating the limitations of conventional photovoltaic module construction that the present invention overcomes. The figure depicts a prior art photovoltaic system 400 showing the typical layered construction including glass fiber 402 composite coating with plastic outer layer 401. For flexible cells, and for EVA adhered rigid glass top sheet positioned over the photovoltaic cell. Light ray paths 210 in the conventional system demonstrate the 10-11% light absorption that occurs in the thick protective coatings before the light can reach the photovoltaically active portions of the solar cells. In accordance with examples, reflected light 220 from the solar material is representative of the inefficiency of the system. The figure also illustrates the straight, unimpeded diffusion pathways available for water and oxygen infiltration through light channels 404 of conventional systems, showing how these degrading agents can readily reach the photovoltaic cell surfaces. Critical failure points are indicated at cracking points 405 where the rigid glass top sheet is prone to cracking and shattering during manufacturing, installation, or environmental impacts, representing the 5-10% failure rate experienced byconventional systems. The comparative illustration emphasizes how conventional approaches suffer from the combined problems of high optical losses, poor barrier properties, and mechanical brittleness that the inventive glass sphere encapsulant system addresses comprehensively.

[0035] In accordance with embodiments of the invention, Figure 4 illustrates the glass sphere size distribution and close-packing arrangements that optimize both the optical performance and barrier properties of the encapsulant system. The figure demonstrates multiple sphere sizes ranging from approximately 4 / 1000 to 25 / 1000 inch in diameter (80-250 um) 80-250 um, showing how normal spheres 501, multimodal spheres 502, and large spheres 503 can be employed to achieve maximum packing density. Large spheres in the upper portion of the size range are shown positioned to create the primary structural framework, while smaller spheres are illustrated filling the interstitial spaces between larger spheres to approach theoretical maximum packing densities of 60-75% sphere volume fraction. The close-packed arrangement is depicted with glass sphere encapsulant layer 203 showing how the configuration maximizes the volume fraction occupied by the optically neutral glass spheres while minimizing the volume of light-absorbing polymer material required to bind the spheres together. Cross-sectional details illustrate how the multiple sphere sizes create a distribution that enhances both the light reflection interfaces and the tortuous path characteristics essential to the barrier properties, with polymer material occupying only the minimal interstitial spaces necessary for structural integrity.

[0036] In accordance with embodiments of the invention, Figure 5a illustrates the conventional diffusion pathways characteristic of prior art encapsulant systems 400, demonstrating the environmental degradation mechanisms that limit photovoltaic module longevity. The figure shows water and oxygen molecules following direct, unimpeded diffusion routes through continuous polymer layers of conventional encapsulant systems. In accordance with an example, reflected light 220 is lost from the system after reflecting from the solar material surface.Degrading species diffusion paths 310 and light rays 210 as the minor path in accordance with an example indicate how degrading agents can diffuse relatively easily through light channels 404 and the long, unobstructed pathways available in conventional organic polymer materials, reaching the photovoltaic cell surfaces where they create oxidation and degradation that progressively reduces operational lifetime and power output. The figure illustrates how conventional systems provide minimal resistance to the infiltration of water and oxygen, with diffusion occurring through continuous polymer phases that offer little impedance to the transport of small molecules.

[0037] In accordance with embodiments of the invention, Figure 5b illustrates the tortuous diffusion pathways created by the close-packed glass sphere arrangements that dramatically enhance the barrier properties of the inventive encapsulant system. The figure demonstrates how- glass spheres 101 create highly circuitous routes for water and oxygen diffusion, with multiple light ray paths 210 showing the complex, elongated pathways that diffusing molecules must navigate around the closely packed spheres. The tortuous path effect is illustrated showing how the necessity for diffusing molecules to navigate around the glass spheres creates much longer and more complex diffusion pathways through light channels 404 compared to conventional systems. The figure shows how the reduced polymer volume achieved through glass sphere packing provides a corresponding reduction in the available diffusion pathways for degrading agents, with the glass spheres effectively occupying space that would otherwise be filled with polymer material through which harmful agents could diffuse. The synergistic effect of increased path tortuosity and reduced polymer cross-sectional area is demonstrated, showing how this dualmechanism approach provides comprehensive protection against water and oxygen infiltration that causes degradation in photovoltaic cell chemistries.

[0038] In accordance with embodiments of the invention, Figure 6a illustrates the pre-formed tape appli cati on method that provides advantages in terms of handling, storage, and precise application to photovoltaic modules. The figure shows the glass sphere encapsulant system formed as roll of inventive tape 601 with glass spheres uniformly distributed throughout the tape structure, applied to old solar panel 600 with top layer 602 and curved structure 702, demonstrating how the degassed encapsulant mixture can be cast or formed into sheet form to achieve a handling consistency suitable for roll-to-roll or sheet-fed application processes. The tape configuration is shown being applied directly onto photovoltaic modules, with the uniform distribution of glass spheres maintaining the close-packed arrangements that optimize both the light reflection mechanism and the tortuous diffusion pathway characteristics, with a contact surface having a substantially uniform structure with spheres placed proximally to the solar cell.

[0039] In accordance with embodiments of the invention, Figure 6b illustrates the flowable coating application method that provides advantages in terms of conform ability to irregular surfaces and the ability to achieve uniform thickness over complex geometries. The figure depicts nozzle 604 applying flowable coating 603 as the glass sphere encapsulant system that can be brushed, sprayed, or otherwise applied directly to photovoltaic modules with top layer 602. The flowable application approach is shown enabling application to irregular surfaces and complex three-dimensional structures, with the fluid viscosity adjusted through temperature control or addition of compatible solvents to optimize application characteristics for specificphotovoltaic module configurations. Heated platens are illustrated for the lamination process that permanently bonds without bubbles the glass sphere encapsulated to the photovoltaic module while ensuring complete interpenetration with underlying structures such as bus bars. The figure demonstrates how both tape and fluid application methods achieve uniform distribution of glass spheres in close-packed arrangements essential to the inventive encapsulant system.

[0040] In accordance with embodiments of the invention, Figure 7a illustrates an application method utilizing stamping techniques for precise placement and formation of the glass sphere encapsulant system. The figure shows heat press 610, solar panel 600, and top layer 602 configured to apply controlled pressure and temperature to form the bubble free encapsulant system with optimal glass sphere distribution and packing density. The stamping process using a silicon mount surface 611 is illustrated creating uniform thickness and consistent sphere arrangement across the photovoltaic module surface, wherein a stamping plate coated with a silicone hump akin to a paint stamping system is used to eliminate intruded gas bubbles. This application method demonstrates the versatility of the inventive encapsulant system in accommodating various manufacturing processes while maintaining the critical glass sphere arrangements necessary for both optical performance and barrier properties enhancement.

[0041] In accordance with embodiments of the invention, Figure 7b illustrates various application configurations that demonstrate the broad applicability of the glass sphere encapsulant system across different photovoltaic technologies and installation requirements. The figure shows top layer 602 and internal spheres evenly sized 620 where the glass sphere encapsulant is formulated as a flexible system that can conform to curved surfaces or be applied in roll-to-roll photovoltaic manufacturing processes. The configuration demonstrates the potential for flexible photovoltaic applications, retrofit applications over existing modules, high-voltage system configurations optimized for photovoltaic systems operating at voltages exceeding 900V, and optional glass fiber reinforcement integration where the glass sphere encapsulant is combined with traditional glass fiber materials to provide supplementary structural reinforcement while maintaining the primary optical and barrier benefits of the glass sphere system.

[0042] In accordance with embodiments of the invention, Figure 8 provides a detailed illustration of the optical performance improvements achieved by the glass sphere encapsulant system, quantifying the light absorption reduction and efficiency enhancements. The figure demonstrates the light reflection mechanism showing how glass spheres 101 create refractive index interfaces at reflection points 300 that systematically redirect reflected light 210 from photovoltaic cell surface 201 back toward the cell for additional energy conversion opportunities.The multiple reflection events that can occur at different sphere-polymer interfaces before light is either absorbed by the photovoltaic cell or eventually escapes from the module are illustrated. The figure demonstrates both the light reflection mechanism with quantified light absorption reduction and the elimination of brittle failure modes with enhanced barrier properties against water and oxygen diffusion through tortuous pathways, showing how the inventive system exhibits approximately 6% or less light absorption compared to the 10-11% absorption characteristic of conventional glass fiber composite coatings.

[0043] In accordance with embodiments of the invention, Figure 9 provides a comprehensive performance benefits comparison chart 800 that quantifies the substantial improvements of the inventive glass sphere encapsulant system across multiple critical metrics compared to conventional photovoltaic encapsulation approaches. The chart displays the benefits associated with embodiments of the inventive solution table 810 as compared to prior art 820 with comparative data showing light absorption performance with the inventive system at 6% versus conventional systems at 10-11%, representing the significant optical efficiency improvements achieved through the light reflection mechanism and reduced polymer volume. Failure rate comparisons demonstrate the elimination of the 5-10% cracking failure rate experienced by conventional rigid glass protective layers during manufacturing, installation, and environmental impacts such as hail. Efficiency improvements from light redirection illustrate the additional gains provided by the light-trapping effect that extends beyond simple absorption reduction, showing how the multiple refractive index interfaces created by the glass spheres provide efficiency enhancements that compound with the reduced absorption benefits. Extended operational lifetime from reduced diffusion quantifies the durability improvements achieved through the tortuous diffusion pathways that dramatically reduce water and oxygen infiltration, demonstrating how the barrier enhancement effect significantly exceeds conventional encapsulant approaches and directly addresses degradation mechanisms affecting virtually all photovoltaic cell chemistries currently in use.

[0044] This description proceeds systematically through several key areas. First, the conventional problems affecting photovoltaic efficiency and durability are illustrated with reference to prior art configurations. Next, the inventive solution is presented in detail, beginning with a high-level overview of how glass spheres solve the identified problems, followed by comprehensive descriptions of the preferred embodiments. The discussion then covers the specific characteristics of the glass sphere component, including size ranges, packing arrangements, and manufacturing methods. The encapsulant material properties and alternatives are addressed, with particular attention to the light transmission and barrier enhancementmechanisms. Manufacturing and application methods are described, followed by alternative embodiments and performance benefits. Throughout this description, the invention is characterized in accordance with embodiments that demonstrate the versatility and broad applicability of the inventive concept across various photovoltaic technologies and configurations.

[0045] In accordance with an embodiment, conventional photovoltaic modules exhibit several fundamental limitations that restrict their efficiency and operational lifetime, as illustrated by examining the typical construction and performance characteristics of existing solar panel systems.

[0046] A conventional photovoltaic module cross-section reveals the structural elements that contribute to these performance limitations. In typical prior art configurations, photovoltaic cells are positioned between protective layers, including glass fiber composite materials combined with adhesive layers such as EVA (ethylene vinyl acetate), and often topped with rigid glass sheets or plastic films like ETFE (ethylene tetrafluoroethylene). While these protective layers serve important functions, they inherently introduce significant energy losses that directly impact the module's power generation capability.

[0047] Quantification of light losses in conventional systems demonstrates the magnitude of this efficiency problem. In accordance with embodiments of existing photovoltaic protection systems, glass fiber composite coatings that combine glass mat with EVA adhesive and ETFE plastic outer layers absorb approximately 10-11% of the total incident light. This substantial light absorption occurs before the photons can reach the photovoltaically active portions of the solar cells, representing a direct reduction in the system's energy conversion potential. The thickness required for these conventional protective coatings compounds this absorption problem, as thicker coatings necessarily absorb greater amounts of incident solar radiation.

[0048] Water and oxygen diffusion represents another critical degradation mechanism affecting conventional photovoltaic modules. In accordance with embodiments of typical solar panel construction, water and oxygen molecules diffuse through the adhesive coatings and penetrate to the edges and surfaces of the photovoltaic cells. This infiltration of oxidizing agents creates a degradation pathway that affects virtually every solar cell chemistry currently in commercial use. The water and oxygen mixture diffuses into the solar cells and progressively impacts the electronic components, reducing operational lifetime and power output over time. This diffusion process is facilitated by the relatively long, unobstructed pathways available through conventional organic polymer materials used in existing encapsulant systems.

[0049] Glass top sheet brittleness presents additional reliability concerns in conventional photovoltaic modules. In accordance with embodiments of prior art protective systems, many existing photovoltaic modules incorporate rigid glass layers positioned over the fragile solar cells to provide mechanical protection. However, these glass top sheets are prone to cracking and shattering during manufacturing processes, installation procedures, or from environmental impacts such as hail storms. Industry data indicates that 5-10% of all solar cell modules experience breakage due to cracking or shattering at some point during manufacturing or installation. This failure rate represents substantial economic losses and reliability concerns that affect the commercial viability of photovoltaic installations.

[0050] The combination of these three primary issues - optical losses from absorptive protective coatings, degradation from water and oxygen infiltration, and mechanical failure of brittle protective layers - creates a compelling need for improved photovoltaic module encapsulation approaches that can address these fundamental limitations while maintaining the protective functions required for long-term outdoor operation.

[0051] In accordance with the invention, the fundamental problems of light losses, water and oxygen diffusion, and brittleness affecting conventional photovoltaic modules are solved by incorporating glass spheres within an encapsulant material to create multiple light-redirecting interfaces while simultaneously establishing tortuous diffusion pathways that dramatically enhance both optical efficiency and barrier properties.

[0052] In accordance with an embodiment of the inventive solution, glass spheres ranging in size from approximately 4 / 1000 to 25 / 1000 inch in diameter are dispersed within a polymer encapsulant material to form a composite protective layer that fundamentally changes how light interacts with the photovoltaic system. The glass spheres are preferably solid rather than hollow to optimize refractive index matching with the encapsulant material, and are advantageously arranged in close-packed configurations using multiple sphere sizes to maximize packing density. The spheres may be manufactured through processes such as melting and spraying droplets to achieve nearly perfectly spherical shapes.

[0053] The inventive glass sphere encapsulant configuration is illustrated in the cross-sectional view of Figure 1, which depicts a photovoltaic module 200 incorporating the glass sphere encapsulant system. As shown in the figure, glass spheres 101 are distributed throughout the encapsulant layer 203, creating multiple refractive index interfaces that redirect reflected light back toward the photovoltaic cell 201 rather than allowing it to escape from the module as waste energy.

[0054] In accordance with embodiments of the invention, this glass sphere encapsulant approach solves each of the identified problems through distinct but complementary mechanisms:

[0055] First, the light loss problem that plagues conventional systems is addressed through the inventive light reflection mechani sm. Rather than allowing the significant portion of light reflected from the photovoltaic cell surface to escape from the module, the glass sphere-polymer interfaces create refractive index differences that redirect this reflected light back toward the photovoltaic cell for additional energy conversion opportunities. This multiple reflection capability within the encapsulant structure represents a fundamental departure from prior art approaches that simply attempt to minimize absorption without capturing reflected energy.

[0056] Second, the water and oxygen diffusion problem is solved through the tortuous diffusion pathways created by the close-packed arrangement of glass spheres. In accordance with embodiments of the invention, the spheres create highly circuitous paths that significantly impede the infiltration of water and oxygen into the photovoltaic cells. This tortuous path effect, combined with the reduced volume of organic polymer material that serves as the primary diffusion medium, substantially enhances the barrier properties compared to conventional encapsulant systems where water and oxygen can diffuse relatively unimpeded through continuous polymer pathways.

[0057] Third, the brittleness problem associated with conventional glass top sheets is eliminated by the flexible nature of the glass sphere encapsulant system. In accordance with embodiments of the invention, the encapsulant provides impact resistance while maintaining optical performance, eliminating the 5-10% failure rate experienced by conventional rigid glass protective layers during manufacturing, installation, or environmental impacts such as hail. The flexible polymer matrix between the glass spheres functions as a protective cushion that can absorb impacts without the catastrophic cracking failure mode characteristic of monolithic glass sheets.

[0058] Additionally, in accordance with embodiments of the invention, the overall light absorption of the system is dramatically reduced compared to conventional approaches. The glass sphere encapsulant exhibits approximately 6% or less light absorption versus the 10-11% absorption characteristic of conventional glass fiber or glass covered composite coatings. This improvement results from the reduced volume of organic polymer material, with the optically neutral glass spheres occupying space that would otherwise contain light-absorbing polymer, while the remaining polymer serves primarily to fill the interstitial spaces between spheres rather than forming thick, continuous absorptive layers.

[0059] In accordance with an embodiment of the invention, the glass sphere component represents the core element where the inventive concept is physically manifest, requiring detailed specification to enable one skilled in the art to practice the invention effectively.

[0060] In accordance with embodiments of the invention, the glass spheres preferably range in diameter from approximately 4 / 1000 of an inch to 25 / 1000 of an inch, which corresponds to a size range of approximately 80 to 600 micrometers (pm), or in various embodiments in the range of approximately 250 micrometers (pm). This size range has been determined to provide optimal performance characteristics for both the light reflection mechanism and the barrier properties enhancement functions of the inventive encapsulant system. The present inventor has observed in various embodiments that spheres smaller than 80 pm may not provide adequate light redirection interfaces, while spheres larger than 250 pm may create undesirable light scattering effects that reduce overall optical efficiency.

[0061] In accordance with embodiments of the invention, solid glass spheres are strongly preferred over hollow glass spheres for refractive index matching considerations. The solid construction eliminates potential refractive index discontinuities that could occur with hollow spheres containing air or other gases, which would create undesired light scattering at the internal sphere interfaces. Solid glass spheres provide consistent refractive index characteristics that optimize the light reflection mechanism at the sphere-polymer boundaries while maintaining structural integrity under processing and operational conditions.

[0062] In accordance with embodiments of the invention, the glass spheres are advantageously arranged in close-packed configurations using multiple sphere sizes to maximize packing density and optimize both optical and barrier properties. The close-packing arrangement utilizes spheres of at least two different sizes, with smaller spheres positioned to fill interstitial spaces between larger spheres. This configuration may achieve packing densities approaching theoretical maximums for sphere packing, typically ranging from approximately 60% to 75% sphere volume fraction within the encapsulant matrix. The multiple sphere sizes create a distribution that enhances both the light reflection interfaces and the tortuous path characteristics essential to the barrier properties.

[0063] In accordance with embodiments of the invention, the glass spheres are preferably manufactured through processes involving melting glass and forming droplets that are allowed to solidify into nearly perfectly spherical shapes. The spherical geometry is critical to the light reflection mechanism, as deviations from spherical shape can create unpredictable light scattering patterns that reduce the efficiency of the light redirection function. Manufacturing methods may include flame-forming processes where glass particles are fed through high-temperature flames, allowing surface tension forces to create the desired spherical geometry as the glass cools and solidifies.

[0064] In accordance with embodiments of the invention, the encapsulant material serves the dual function of binding the glass spheres together while providing the refractive index contrast necessary for the light reflection mechanism to operate effectively.

[0065] In accordance with a preferred embodiment of the invention, the encapsulant material comprises a silicone-based material, most preferably DOWSIL 6326, which has demonstrated superior light transmission properties during testing. In an embodiment, the encapsulant material is solar rated. DOWSIL 6326 represents an optimal balance of optical clarity, processing characteristics, and long-term stability under outdoor photovoltaic operating conditions. This material exhibits exceptional light transmission capabilities that contribute directly to the overall efficiency improvements achieved by the inventive encapsulant system.

[0066] In accordance with alternative embodiments of the invention, other encapsulant materials may be employed depending on specific application requirements, including optical urethanes and other silicone encapsulates. Optical urethanes may provide advantages in certain processing conditions or where specific mechanical properties are desired. Alternative silicone encapsulants may be selected based on factors such as processing temperature requirements, curing characteristics, or compatibility with specific photovoltaic cell chemistries. The selection criteria for encapsulant materials include optical transparency, refractive index characteristics relative to the glass spheres, processing compatibility, and long-term environmental stability.

[0067] In accordance with embodiments of the invention, the volume ratios of glass spheres to encapsulant material are optimized to achieve both the light reflection functionality and the barrier properties enhancement while maintaining processability. Preferred volume ratios typically range from approximately 1:1 to achieve optimal packing density while ensuring adequate encapsulant material to fill interstitial spaces and provide structural integrity. The encapsulant material volume is minimized to the extent necessary to bind the spheres together and fill void spaces, thereby maximizing the volume fraction occupied by the optically neutral glass spheres.

[0068] In accordance with embodiments of the invention, the light transmission properties of the inventive encapsulant system demonstrate significant improvements over prior art approaches, exhibiting light absorption of approximately 6% or less compared to the 10-11% absorption characteristic of conventional glass fiber or glass covered composite coatings. This improvement results directly from the reduced volume of organic polymer material, with the glass spheres occupying space that would otherwise contain light-absorbing polymer. The remainingencapsulant material serves primarily to fill interstitial spaces between spheres rather than forming continuous thick layers that would absorb incident light.

[0069] In accordance with embodiments of the invention, the light reflection mechanism represents a fundamental departure from prior art approaches by actively redirecting reflected light back toward the photovoltaic cell rather than allowing such light to escape as waste energy.

[0070] In accordance with embodiments of the invention, the light reflection mechanism operates through strategically positioned refractive index interfaces created at the boundaries between the glass spheres and the encapsulant polymer material. When light reflected from the photovoltaic cell surface encounters these sphere-polymer interfaces, the difference in refractive indices between the glass spheres and the encapsulant material causes a portion of the reflected light to be redirected back toward the photovoltaic cell. This redirection process provides additional opportunities for energy conversion that would otherwise be lost in conventional encapsulant systems.

[0071] In accordance with embodiments of the invention, the refractive index differences at the sphere-polymer interfaces create multiple reflection opportunities within the encapsulant structure. Light that is not initially absorbed by the photovoltaic cell and is reflected back through the encapsulant encounters numerous sphere-polymer interfaces, each providing a probability of redirection back toward the photovoltaic cell. The cumulative effect of these multiple interfaces significantly increases the probability that reflected light will be returned to the photovoltaic cell for additional energy conversion opportunities rather than escaping from the module.

[0072] In accordance with embodiments of the invention, the multiple reflection paths within the encapsulant structure create a light-trapping effect that enhances overall photovoltaic efficiency. Light entering the encapsulant system may undergo several reflection events at different sphere-polymer interfaces before either being absorbed by the photovoltaic cell or eventually escaping from the module. This multiple-reflection process effectively increases the optical path length of light within the photovoltaic system, thereby increasing the probability of photon absorption and energy conversion.

[0073] In accordance with embodiments of the invention, the barrier properties enhancement mechanism provides significant improvement in photovoltaic module longevity by dramatically reducing the diffusion of water and oxygen into the photovoltaic cells.

[0074] In accordance with embodiments of the invention, the close-packed arrangement of glass spheres creates highly tortuous diffusion pathways that significantly impede the infiltration of water and oxygen molecules into the photovoltaic cells. The tortuous path effect results from thenecessity for diffusing molecules to navigate around the closely packed spheres, creating a much longer and more complex diffusion pathway compared to conventional encapsulant systems where molecules can diffuse relatively unimpeded through continuous polymer layers. This increased path length corresponds to dramatically increased diffusion times, effectively providing enhanced barrier properties.

[0075] In accordance with embodiments of the invention, the reduced polymer volume achieved through the glass sphere packing arrangement provides a corresponding reduction in the available diffusion pathways for degrading agents. Since water and oxygen diffusion occurs primarily through the organic polymer phase rather than through the glass spheres themselves, the minimization of polymer volume directly reduces the cross-sectional area available for diffusion. The glass spheres effectively occupy space that would otherwise be filled with polymer material, thereby reducing the total volume of material through which harmful agents can diffuse to reach the photovoltaic cells.

[0076] In accordance with embodiments of the invention, the combination of increased diffusion path tortuosity and reduced polymer volume creates a synergistic barrier enhancement effect that significantly exceeds the protection provided by conventional encapsulant approaches. This dual¬ mechanism approach addresses both the path length and cross-sectional area factors that determine diffusion rates, providing comprehensive protection against the water and oxygen infiltration that causes degradation in virtually all photovoltaic cell chemistries currently in use.

[0077] In accordance with an embodiment of the invention, the disclosure of US Patent Application Publication No. 2006 / 0201545 Al to Ovshinsky et al., published September 14, 2006, and entitled " Fire Resistant Laminate and Photovoltaic Module Incorporating the Fire Resistant Laminate," (referred to herein as “the Ovshinsky reference” or “Ovshinsky”) is hereby incorporated by reference in its entirety for all purposes.

[0078] In accordance with embodiments of the invention, the Ovshinsky reference provides several foundational teachings that are useful to understanding and implementing the present inventive concept, while the present invention represents a significant departure from the disclosed approach both in terms of the problem addressed and the solution mechanism employed.

[0079] In accordance with embodiments of the invention, the Ovshinsky reference provides valuable teaching regarding the basic feasibility and implementation of glass sphere encapsulant systems for photovoltaic applications. Specifically, Ovshinsky teaches that glass spheres ranging in diameter from about 80 pm to about 250 pm may be successfully incorporated into photovoltaic module encapsulants. The reference demonstrates that solid glass spheres arepreferred over hollow glass spheres to avoid interference with refractive index characteristics, a teaching that proves useful in the present invention's implementation of the light reflection mechanism.

[0080] In accordance with embodiments of the invention, Ovshinsky further teaches useful manufacturing and implementation approaches for glass sphere encapsulant systems. The reference discloses that glass spheres may be mixed with various encapsulant materials and that multiple sphere sizes may be employed to achieve improved packing arrangements. Ovshinsky demonstrates that glass spheres may be incorporated at volume ratios approaching 1: 1 with the encapsulant material, and that the resulting composite may be applied as encapsulant layers in photovoltaic module construction.

[0081] In accordance with embodiments of the invention, the Ovshinsky reference provides important teaching regarding the basic structural arrangements suitable for glass sphere encapsulant systems. The reference illustrates various configurations in which glass spherecontaining encapsulants may be applied to photovoltaic cells, including encapsulation of the entire photovoltaic device and selective application to the light-incident surface. These structural teachings inform the implementation options available for the present inventive system.

[0082] In accordance with the invention, however, the present glass sphere encapsulant system represents a fundamental departure from the Ovshinsky disclosure in both the problem addressed and the solution mechanism employed. While Ovshinsky's primary focus was achieving fire resistance in photovoltaic modules through replacement of flammable organic materials with inert glass spheres, the present invention addresses an entirely different set of problems related to light losses, water and oxygen diffusion, and optical efficiency enhancement.

[0083] In accordance with an embodiment of the inventive departure, the present invention recognizes and exploits a previously unappreciated optical phenomenon wherein glass spheres create refractive index interfaces that redirect reflected light back toward the photovoltaic cell rather than allowing such light to escape as waste energy. Ovshinsky's disclosure contains no teaching or suggestion of this light reflection mechanism, nor does it recognize the potential for using glass spheres to capture and redirect reflected light for additional energy conversion opportunities. The present invention's recognition that reflected light from photovoltaic cells can be systematically redirected back to the cells through strategically positioned glass sphere interfaces represents a significant advance beyond Ovshinsky's fire-resistance-focused approach.

[0084] In accordance with an embodiment of the inventive departure, the present invention employs fundamentally different encapsulant materials to optimize the light reflection mechanism. While Ovshinsky teaches the use of EVA (ethylene vinyl acetate) and similarconventional photovoltaic encapsulants, the present invention preferably employs silicone-based materials such as DOWSIL 6326. This material selection is driven not by fire resistance considerations as in Ovshinsky, but by the need to optimize refractive index characteristics and light transmission properties to achieve maximum effectiveness of the light reflection mechanism. The present invention's encapsulant material choices result in light absorption of 6% or less compared to the 10-11% absorption characteristic of conventional approaches.

[0085] In accordance with an embodiment of the inventive departure, the present invention recognizes and exploits the tortuous diffusion pathway enhancement provided by close-packed glass sphere arrangements as a primary benefit for improving photovoltaic module longevity. While Ovshinsky mentions the presence of glass spheres in encapsulant materials, the reference does not recognize or teach the specific barrier enhancement mechanism achieved through the tortuous pathways created by close-packed sphere arrangements. The present invention's understanding that glass spheres can dramatically reduce water and oxygen diffusion rates by creating highly circuitous diffusion paths represents a significant advance in photovoltaic durability enhancement beyond the fire resistance focus of Ovshinsky.

[0086] In accordance with an embodiment of the inventive departure, the present invention addresses the problem of glass top sheet brittleness through a flexible encapsulant approach that eliminates the need for rigid protective layers. While Ovshinsky continues to contemplate the use of conventional rigid protective structures, the present invention recognizes that the glass sphere encapsulant itself can provide impact resistance while maintaining optical performance, thereby eliminating the 5-10% failure rate experienced by conventional rigid glass protective layers. This represents a fundamental shift from protective layer supplementation to protective layer replacement.

[0087] In accordance with embodiments of the invention, the present inventive approach therefore represents a comprehensive reconceptualization of photovoltaic encapsulant systems that departs significantly from Ovshinsky's fire-resistance-focused disclosure to address fundamental efficiency and durability limitations through novel optical and barrier enhancement mechanisms not taught or suggested in the prior art.

[0088] In accordance with embodiments of the invention, the glass sphere encapsulant system may be manufactured and applied through various processing methods that optimize both the optical and barrier properties of the inventive encapsulant while maintaining compatibility with standard photovoltaic module production techniques.

[0089] In accordance with embodiments of the invention, the manufacturing process begins with the preparation and mixing of the glass spheres with the encapsulant material to achieve optimaldispersion and packing characteristics. The glass spheres are preferably prepared by preheating to above 100°C for approximately 5 minutes in a vacuum environment greater than 25 inches Hg to remove moisture and air from the sphere surfaces that could interfere with bonding. The spheres are then allowed to cool in an inert gas atmosphere before incorporation into the encapsulant material.

[0090] In accordance with embodiments of the invention, the mixing process employs standard mixing methods to combine the glass spheres with the silicone encapsulant material, most preferably DOWSIL 6326 in accordance with the preferred embodiment. The mixing process is carefully controlled to achieve the desired volume ratios while preventing damage to the spherical geometry of the glass beads. Multiple sphere sizes are advantageously incorporated during the mixing process to optimize close-packing arrangements, with smaller spheres filling interstitial spaces between larger spheres.

[0091] In accordance with embodiments of the invention, the mixing parameters are selected to ensure uniform distribution of the glass spheres throughout the encapsulant matrix while maintaining the integrity of the sphere-polymer interfaces that are critical to the light reflection mechanism. The mixing process may employ various techniques including mechanical stirring, planetary mixing, or other methods suitable for viscous polymer systems containing solid particulate matter.

[0092] In accordance with embodiments of the invention, degassing procedures are implemented to eliminate entrapped air that could create voids or optical discontinuities within the encapsulant system. The degassing process is particularly important given the close-packed arrangement of glass spheres, which can trap air in interstitial spaces during the mixing process.

[0093] In accordance with embodiments of the invention, the degassing may be accomplished through vacuum degassing techniques wherein the mixed encapsulant material is subjected to reduced pressure conditions to allow entrapped gases to escape. The degassing process is continued until substantially all visible air bubbles have been eliminated from the encapsulant mixture. The degassing conditions are selected to be compatible with the encapsulant material properties while ensuring complete air removal without causing premature curing or other adverse effects.

[0094] In accordance with embodiments of the invention, the degassed encapsulant mixture exhibits improved optical clarity and enhanced structural integrity compared to non-degassed systems, contributing directly to the optical efficiency improvements achieved by the inventive encapsulant system.,0

[0095] In accordance with embodiments of the invention, the glass sphere encapsulant system may be applied to photovoltaic modules in various forms to accommodate different manufacturing processes and module configurations.

[0096] In accordance with a first embodiment of the application process, the encapsulant may be pre-formed as a tape that can be applied directly onto photovoltaic cells. The tape form provides advantages in terms of handling, storage, and precise application to photovoltaic modules. The tape may be manufactured by casting or forming the degassed encapsulant mixture into sheet form and allowing it to achieve a handling consistency suitable for roll-to-roll or sheet-fed application processes.

[0097] In accordance with an alternative embodiment of the application process, the encapsulant may be applied as a flowable coating that can be brushed, sprayed, or otherwise applied directly to photovoltaic modules. This fluid application approach provides advantages in terms of conformability to irregular surfaces and the ability to achieve uniform thickness over complex geometries. The fluid viscosity may be adjusted through temperature control or the addition of compatible solvents or thinning agents to optimize the application characteristics for specific photovoltaic module configurations.

[0098] In accordance with embodiments of the invention, both tape and fluid application methods are designed to achieve uniform distribution of the glass spheres in close-packed arrangements that optimize both the light reflection mechanism and the tortuous diffusion pathway characteristics essential to the inventive encapsulant system.

[0099] In accordance with embodiments of the invention, lamination processes are employed to permanently bond the glass sphere encapsulant to the photovoltaic module while ensuring complete interpenetration of the encapsulant material with any underlying structures such as bus bars or grid connections.

[0100] In accordance with embodiments of the invention, the lamination process may employ standard photovoltaic lamination equipment with process parameters optimized for the glass sphere encapsulant system. The lamination may be accomplished using heated platens with controlled pressure application to ensure uniform bonding while avoiding damage to the glass spheres or displacement of the close-packed sphere arrangements.

[0101] In accordance with embodiments of the invention, the lamination process parameters including temperature, pressure, and time are selected to achieve complete curing of the encapsulant material while maintaining the optical and barrier properties of the glass sphere system. The process may employ vacuum lamination techniques to ensure complete air removal and intimate contact between the encapsulant and photovoltaic cell surfaces.

[0102] In accordance with embodiments of the invention, special attention is given during lamination to ensure that the glass sphere encapsulant penetrates completely around bus bars and other three-dimensional structures on the photovoltaic cell surface, thereby providing comprehensive encapsulation without void formation. The lamination process may include sequential heating and cooling cycles to optimize the flow characteristics of the encapsulant material during processing while achieving final properties optimized for long-term photovoltaic module operation.

[0103] In accordance with embodiments of the invention, the completed lamination process results in a photovoltaic module wherein the glass sphere encapsulant provides both the optical efficiency improvements through light redirection and the enhanced barrier properties through tortuous diffusion pathways, while maintaining the mechanical protection and weather resistance required for outdoor photovoltaic applications.

[0104] In accordance with alternative embodiments of the invention, the glass sphere encapsulant system demonstrates remarkable versatility and adaptability across a broad range of photovoltaic applications, manufacturing approaches, and system configurations while consistently delivering the fundamental benefits of enhanced light reflection, improved barrier properties, and elimination of brittle failure modes,

[0105] In accordance with embodiments of the invention, various distributions of glass sphere sizes may be employed to optimize the close-packing characteristics and optical performance for specific photovoltaic applications. While the preferred size range encompasses spheres from approximately 4 / 1000 to 25 / 1000 inch in diameter (80-250 μm), alternative embodiments may utilize different size distribution strategies to achieve particular performance objectives.

[0106] In accordance with an embodiment, bimodal size distributions may be employed wherein large spheres in the upper portion of the size range (approaching 250 μm diameter) are combined with small spheres in the lower portion of the size range (approaching 80 μm diameter) to achieve maximum packing density. This approach maximizes the volume fraction occupied by the optically neutral glass spheres while minimizing the volume of light-absorbing polymer material required to bind the spheres together.

[0107] In accordance with alternative embodiments, trimodal or multimodal size distributions may be implemented to further optimize packing efficiency. Such distributions may include large spheres, intermediate spheres, and small spheres in carefully selected ratios that enable the smaller spheres to fill progressively smaller interstitial spaces, approaching theoretical maximum packing densities, and thus decreasing costs.

[0108] In accordance with embodiments adapted for specific optical requirements, narrow size distributions may be employed where the majority of spheres fall within a limited size range. Such embodiments may be particularly suited for applications where uniform light scattering characteristics or consistent refractive index interfaces are desired for specialized photovoltaic cell designs.

[0109] In accordance with embodiments of the invention, various encapsulant materials may be selected based on specific performance requirements, processing constraints, or cost considerations while maintaining the fundamental light reflection and barrier enhancement mechanisms.

[0110] In accordance with a preferred embodiment, silicone-based encapsulant materials provide superior optical and processing characteristics, with DOWSIL 6326 representing an optimal balance of light transmission, processing compatibility, and long-term stability. However, alternative silicone formulations may be selected based on specific curing requirements, temperature resistance, or adhesion characteristics needed for particular photovoltaic module designs.

[0111] In accordance with alternative embodiments, optical urethanes may be employed as the encapsulant material where specific mechanical properties or processing advantages are desired. Optical urethanes may provide enhanced flexibility, impact resistance, or chemical compatibility with certain photovoltaic cell materials or substrates. The refractive index characteristics of the selected urethane formulation should be optimized relative to the glass sphere refractive index to maximize the effectiveness of the light reflection mechanism.

[0112] In accordance with embodiments adapted for specialized applications, other optically transparent polymer systems may be employed including modified acrylics, specialized epoxies, or hybrid organic-inorganic materials. The selection criteria for such alternative encapsulant materials include optical clarity in the relevant wavelength ranges, appropriate refractive index relationships with the glass spheres, long-term environmental stability, and processing compatibility with the glass sphere incorporation methods.

[0113] In accordance with embodiments requiring enhanced barrier properties, encapsulant materials with inherently low permeability to water and oxygen may be selected to complement the tortuous path enhancement provided by the glass spheres. Such materials may include fluoropolymer-modified systems or materials incorporating additional barrier additives that work synergistically with the glass sphere tortuous path mechanism.

[0114] In accordance with embodiments of the invention, the glass sphere encapsulant system may be applied in numerous configurations to accommodate different photovoltaic module designs, manufacturing processes, and installation requirements.

[0115] In accordance with an embodiment optimized for flexible photovoltaic applications, the glass sphere encapsulant may be formulated as a flexible tape that can conform to curved surfaces or be applied to roll-to-roll photovoltaic manufacturing processes. The tape configuration provides advantages in terms of handling, storage, and precise application to photovoltaic modules with complex geometries.

[0116] In accordance with embodiments adapted for in-situ application, the glass sphere encapsulant may be formulated as a flowable coating that can be brushed, sprayed, or otherwise applied directly to photovoltaic modules during manufacturing or field installation. This approach enables application to irregular surfaces, complex three-dimensional structures, or photovoltaic installations where pre-formed encapsulant sheets would be impractical.

[0117] In accordance with embodiments designed for retrofit applications, the glass sphere encapsulant may be applied as a protective coating over existing photovoltaic modules to enhance their optical efficiency and extend their operational lifetime. Such retrofit applications may be particularly valuable for upgrading existing photovoltaic installations where the benefits of improved light capture and enhanced barrier properties can extend the economic life of the system.

[0118] In accordance with embodiments incorporating additional protective features, the glass sphere encapsulant may be combined with traditional glass fiber materials to provide supplementary structural reinforcement while maintaining the primary optical and barrier benefits. Such hybrid configurations may be particularly suitable for applications requiring exceptional mechanical strength or cut resistance while preserving the light reflection and diffusion barrier advantages of the glass sphere system.

[0119] In accordance with embodiments adapted for high-voltage photovoltaic systems, the glass sphere encapsulant thickness and composition may be optimized to provide enhanced dielectric breakdown resistance while maintaining optical performance. Such embodiments address the critical safety requirements for photovoltaic systems operating at voltages exceeding 900V where conventional encapsulant approaches may prove inadequate.

[0120] In accordance with embodiments of the invention, the glass sphere encapsulant system provides universal applicability across virtually all photovoltaic cell chemistries due to its fundamental mechanism of action and material compatibility characteristics.

[0121] In accordance with embodiments optimized for silicon-based photovoltaic technologies, including monocrystalline, poly crystalline, and amorphous silicon cells, the glass sphere encapsulant provides significant efficiency improvements through enhanced light capture and reduced parasitic light losses. The refractive index characteristics of the glass spheres and encapsulant materials may be specifically optimized for the optical properties of silicon-based photovoltaic materials to maximize light reflection effectiveness.

[0122] In accordance with embodiments adapted for compound semiconductor photovoltaic cells, including gallium arsenide, indium gallium phosphide, and other III-V semiconductor systems, the glass sphere encapsulant maintains its light reflection and barrier enhancement functions while providing compatibility with the processing requirements of these advanced photovoltaic technologies. The chemical inertness of the glass spheres ensures compatibility with the sensitive surface chemistries characteristic of compound semiconductor devices.

[0123] In accordance with embodiments designed for emerging photovoltaic technologies, including perovskite cells, organic photovoltaic devices, and dye-sensitized solar cells, the glass sphere encapsulant provides both optical enhancement and critical environmental protection. These emerging technologies often exhibit particular sensitivity to water and oxygen degradation, making the barrier enhancement provided by the tortuous diffusion pathways especially valuable for extending operational lifetime.

[0124] In accordance with embodiments optimized for thin-film photovoltaic technologies, including cadmium telluride, copper indium gallium selenide (CIGS), and other thin-film approaches, the glass sphere encapsulant provides mechanical protection for the fragile thin-film structures while enhancing optical performance. The flexible nature of the encapsulant eliminates the mechanical stress concentrations that can occur with rigid protective layers, thereby reducing the likelihood of thin-film cracking or delamination.

[0125] In accordance with embodiments adapted for concentrator photovoltaic applications where high light intensities are directed onto small, high-efficiency cells, the glass sphere encapsulant provides enhanced light management capabilities that can improve the uniformity of light distribution while providing thermal management benefits through improved heat dissipation. The multiple light reflection paths created by the glass sphere interfaces can help homogenize concentrated light beams and reduce hot-spot formation that could otherwise limit concentrator photovoltaic performance.

[0126] In accordance with embodiments tailored for specific wavelength ranges or spectral responses, the glass sphere size distribution and encapsulant material properties may be optimized to enhance light capture for particular portions of the solar spectrum that are mostefficiently converted by specific photovoltaic cell chemistries. This approach enables customization of the optical enhancement effects to match the spectral response characteristics of different photovoltaic technologies, thereby maximizing the efficiency improvements achieved through the inventive encapsulant system.

[0127] In accordance with embodiments of the invention, the glass sphere encapsulant system provides quantifiable and substantial performance improvements across multiple critical metrics compared to conventional photovoltaic encapsulation approaches, demonstrating the significant advantages achieved through the inventive light reflection and barrier enhancement mechanisms.

[0128] In accordance with embodiments of the invention, the optical efficiency improvements achieved by the glass sphere encapsulant system are both measurable and significant compared to conventional approaches. The inventive system exhibits light absorption of approximately 6% or less compared to the 10-11% absorption characteristic of conventional glass fiber or glass covered composite coatings that combine glass mat with EVA adhesive and ETFE plastic outer layers. This represents a reduction of approximately 40-50% in parasitic light losses, directly translating to improved photovoltaic power generation.

[0129] In accordance with embodiments of the invention, the light reflection mechanism provides additional efficiency gains beyond the reduced absorption losses. The multiple refractive index interfaces created by the glass spheres systematically redirect reflected light from the photovoltaic cell surface back toward the cell for additional energy conversion opportunities. This light-trapping effect effectively increases the optical path length within the photovoltaic system, providing efficiency improvements that compound with the reduced absorption benefits to deliver overall system performance enhancements that significantly exceed those achievable through absorption reduction alone.

[0130] In accordance with embodiments of the invention, the tortuous diffusion pathways created by the close-packed glass sphere arrangements provide substantial durability improvements by dramatically reducing the infiltration of water and oxygen into photovoltaic cells. The combination of increased diffusion path length and reduced organic polymer volume creates a barrier enhancement effect that significantly exceeds conventional encapsulant approaches, directly addressing the degradation mechanisms that affect virtually all photovoltaic cell chemistries currently in use.

[0131] In accordance with embodiments of the invention, the durability enhancements translate to extended operational lifetime for photovoltaic modules incorporating the glass sphere encapsulant system. By impeding the diffusion of oxidizing agents that progressively damage electronic components over time, the inventive encapsulant system maintains photovoltaicperformance over extended periods compared to conventional systems where water and oxygen infiltration causes steady degradation of power output.

[0132] In accordance with embodiments of the invention, the flexible nature of the glass sphere encapsulant system eliminates the brittleness problems associated with conventional rigid glass protective layers. The inventive approach eliminates the 5-10% failure rate experienced by conventional photovoltaic modules due to cracking or shattering of glass top sheets during manufacturing, installation, or environmental impacts such as hail.

[0133] In accordance with embodiments of the invention, the glass sphere encapsulant provides impact resistance through the flexible polymer matrix between the glass spheres, which functions as a protective cushion that can absorb impacts without the catastrophic cracking failure mode characteristic of monolithic glass sheets. This flexible protection mechanism maintains optical performance while providing mechanical resilience that extends module reliability throughout manufacturing, installation, and operational phases.

[0134] In accordance with embodiments of the invention, the replacement of flammable organic polymer material with inert glass spheres inherently improves the fire resistance characteristics of the encapsulant system. The glass spheres occupy space that would otherwise be filled with combustible polymer material, thereby reducing the total volume of flammable material within the encapsulant while maintaining structural and optical performance.

[0135] In accordance with embodiments of the invention, the fire resistance improvements are achieved without compromising the primary optical and barrier enhancement functions of the encapsulant system. The glass spheres serve the dual purpose of providing the light reflection and tortuous diffusion pathway benefits while simultaneously reducing fire propagation risk through displacement of organic material with inert glass content.

[0136] In accordance with the preferred embodiment of the invention, a photovoltaic encapsulant system comprises glass spheres ranging in diameter from approximately 4 / 1000 to 25 / 1000 inch (80-250 μm), preferably solid rather than hollow to optimize refractive index characteristics, arranged in close-packed configurations using multiple sphere sizes to maximize packing density. The glass spheres are advantageously manufactured through processes such as melting and spraying droplets to achieve nearly perfectly spherical shapes.

[0137] In accordance with the preferred embodiment, the glass spheres are dispersed within a silicone-based encapsulant material, most preferably DOWSIL 6326, which provides superior light transmission properties. The encapsulant material serves to bind the glass spheres together while providing the refractive index contrast necessary for the light reflection mechanism to operate effectively. The volume ratios of glass spheres to encapsulant material are optimized toachieve both light reflection functionality and barrier properties enhancement while maintaining processability, typically ranging from approximately 1:1 to maximize sphere volume fraction while ensuring adequate encapsulant material to fill interstitial spaces.

[0138] In accordance with the preferred embodiment, the manufacturing process involves mixing the glass spheres with the silicone encapsulant material using standard mixing methods, followed by degassing procedures to eliminate trapped air. The resulting encapsulant may be applied as a pre-formed tape or as a flowable coating that can be applied directly to photovoltaic modules, followed by lamination processes to permanently bond the encapsulant to the photovoltaic cell while ensuring complete interpenetration with underlying structures.

[0139] In accordance with the preferred embodiment, the completed glass sphere encapsulant system provides: (1) light absorption of 6% or less compared to 10-11% for conventional systems; (2) systematic redirection of reflected light back toward photovoltaic cells through refractive index interfaces at sphere-polymer boundaries; (3) enhanced barrier properties through tortuous diffusion pathways that significantly impede water and oxygen infiltration; (4) elimination of brittle failure modes associated with conventional glass top sheets; and (5) improved fire resistance through replacement of organic polymer material with inert glass spheres. These combined benefits represent a fundamental improvement in photovoltaic encapsulation technology that addresses the critical limitations of light losses, environmental degradation, mechanical failure, and fire safety that have long constrained the efficiency, durability, and reliability of conventional photovoltaic systems.

[0140] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.

Claims

CLAIMSWe claim:

1. A photovoltaic encapsulant system comprising:glass spheres dispersed within an encapsulant material to form a composite protective layer, wherein the glass spheres create refractive index interfaces that redirect reflected light from a photovoltaic cell surface back toward the photovoltaic cell for additional energy conversion opportunities while simultaneously establishing tortuous diffusion pathways that impede infiltration of water and oxygen into the photovoltaic cell.

2. The photovoltaic encapsulant system of claim 1, wherein the glass spheres range in diameter from approximately 4 / 1000 to 25 / 1000 inch.

3. The photovoltaic encapsulant system of claim 2, wherein the glass spheres range in diameter from approximately 80 to 600 micrometers.

4. The photovoltaic encapsulant system of claim 1, wherein the glass spheres are solid rather than hollow to optimize refractive index matching with the encapsulant material.

5. The photovoltaic encapsulant system of claim 1, wherein the glass spheres are arranged in close-packed configurations using multiple sphere sizes to maximize packing density.

6. The photovoltaic encapsulant system of claim 5, wherein smaller spheres are positioned to fill interstitial spaces between larger spheres.

7. The photovoltaic encapsulant system of claim 1, wherein the glass spheres are manufactured through processes involving melting glass and forming droplets that solidify into nearly perfectly spherical shapes.

8. The photovoltaic encapsulant system of claim 1, wherein the encapsulant material comprises a silicone-based material.

9. The photovoltaic encapsulant system of claim 8, wherein the silicone-based material is DOWSIL 6326.

10. The photovoltaic encapsulant system of claim 1, wherein the encapsulant material comprises optical urethanes.

11. The photovoltaic encapsulant system of claim 1, wherein volume ratios of glass spheres to encapsulant material are optimized to achieve both light reflection functionality and barrier properties enhancement while maintaining processability,12. The photovoltaic encapsulant system of claim 11, wherein the volume ratios range from approximately 1:1 to maximize sphere volume fraction while ensuring adequate encapsulant material to fill interstitial spaces.

13. The photovoltaic encapsulant system of claim 1, wherein the encapsulant system exhibits light absorption of approximately 6% or less compared to 10-11% absorption characteristic of conventional glass fiber or glass covered composite coatings.

14. A method of manufacturing a photovoltaic encapsulant system comprising:mixing glass spheres with an encapsulant material using standard mixing methods to achieve optimal dispersion and packing characteristics, and degassing the mixture to eliminate entrapped air.

15. The method of claim 14, further comprising preheating the glass spheres to above 100°C for approximately 5 minutes in a vacuum environment greater than 25 inches Hg to remove moisture and air from sphere surfaces.

16. The method of claim 14, wherein the mixing process incorporates multiple sphere sizes during mixing to optimize close-packing arrangements with smaller spheres filling interstitial spaces between larger spheres.

17. The method of claim 14, wherein the degassing is accomplished through vacuum degassing techniques wherein the mixed encapsulant material is subjected to reduced pressure conditions to allow entrapped gases to escape.

18. A method of applying a photovoltaic encapsulant system comprising:applying the encapsulant system of claim 1 to photovoltaic modules in the form of a pre-formed tape that can be applied directly onto photovoltaic cells.

19. A method of applying a photovoltaic encapsulant system comprising:applying the encapsulant system of claim 1 as a flowable coating that can be brushed, sprayed, or otherwise applied directly to photovoltaic modules.

20. The method of claim 19, wherein the fluid viscosity is adjusted through temperature control or addition of compatible solvents to optimize application characteristics for specific photovoltaic module configurations.

21. A photovoltaic module comprising:a photovoltaic cell and the photovoltaic encapsulant system of claim 1 positioned to cover a light incident side of the photovoltaic cell.

22. The photovoltaic module of claim 21, wherein the encapsulant system provides impact resistance through a flexible polymer matrix between the glass spheres that functions as a protective cushion.

23. The photovoltaic module of claim 21, wherein the encapsulant system eliminates need for rigid glass top sheets that are prone to cracking and shattering.

24. The photovoltaic module of claim 21, wherein the life of the ceil is improved by the tortuous diffusion pathways created by close-packed glass sphere arrangements significantly impede infiltration of water and oxygen into the photovoltaic cell.

25. The photovoltaic module of claim 21, wherein the photovoltaic cell comprises silicon-based photovoltaic technology.

26. The photovoltaic module of claim 21, wherein the photovoltaic cell comprises compound semiconductor photovoltaic technology.

27. The photovoltaic module of claim 21, wherein the photovoltaic cell comprises thin-film photovoltaic technology.

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