Multi-axis torus ring segmented ellipsoid optical concentration device for CPV module

Abstract

The present invention discloses a multi -axis torus ring segmented ellipsoid optical concentration device (100) for CPV module that includes a primary optical element (104), a secondary optical element (108) and a multi -junction cell (112). The primary optical element (POE) (104) is an arcuate shaped structure that includes plurality of torus ring segments (204). The second optical element (SOE)(108) is a sphere that cut at a predefined position that encloses the multi¬ junction cell (112). The solar rays (124) fall incident onto the primary optical element (POE) (104) that reduces the focal length so that the fall incident onto the secondary optical element (SOE) (112) which is positioned at a closer distance. The device of the present invention leads to higher amount of energy generation with more Concentration ratio, more CAP and less f-number.

Description

[0001] “MULTI-AXIS TORUS RING SEGMENTED ELLIPSOID OPTICAL

[0002] CONCENTRATION DEVICE FOR CPV MODULE”

[0003] FIELD OF THE INVENTION:

[0004] The present invention relates to an optical concentration device for Concentrator Photovoltaic (CPV) module, more particularly to a multi-axis torus ring segmented ellipsoid optical concentration device for CPV module.

[0005] BACKGROUND OF THE INVENTION:

[0006] Fossil fuels are traditional sources of energy that are a result of animal and plant remnants buried deep within the Earth’s crust. Fossil fuels include conventionally opted fuels such as coal, oil and natural gas. However, these fossil fuels are non-renewal sources of energy, i.e, these are depleting at a rapid rate, while simultaneously causing great harm to the planet as a whole. Burning of fossil fuels result in release of carbon-dioxide, air and water pollution and is the main cause of global warming. In such a scenario, it is important to turn to other alternatives to the conventional fuel options.

[0007] Solar energy is the radiant energy from the sun, that is captured and converted into usable forms of energy like electricity or heat. It is a renewable and abundant resource, that offers a cleaner alternative to fossil fuels. Further, solar energy generates minimal greenhouse gas emissions, making solar energy a major source of non-conventional energy source that is promoted as a solution to the rapid depletion of conventional energy sources such as fossil fuels, petroleum, natural gas and the like.

[0008] Conventionally, solar energy is harnessed through photovoltaic (PV) panels, solar thermal collectors, and concentrated solar power (CSP). However, harvesting solar energy efficiently is a challenge. Photovoltaics (PVs) are commonly used to convert light energy to electricity through semiconductors that exhibit photovoltaic effect. These PVs currently used have a capacity to cross 1 Terawatt (TW) and are installed world-wide.

[0009] In this PV technology, there are few types of photovoltaics being currently used. First, the single-crystalline silicon (sc-Si)(single junction) solar cells normally have a laboratory efficiency between 25% to 27% and a commercial panel efficiency between 20% to 23%. These sc-Si solar cells have lesser efficiencies and they are able to convert only a narrow spectrum of solar rays from 400-1000nm. Further, in hot-climates, the power generation of sc-Si solar device is seen to have reduced by about 0.37% for every 1° cell temperature rise above the 25° C standard test condition. The second type of photovoltaics are the multi -junction solar cells (MJs). In MJs, multiple solar cell materials with different bandgaps are stacked to absorb a varied spectrum of light and increase efficiency of the cell. As of today, 4 junction solar cells have achieved an efficiency of 47.6%.

[0010] In regions with high direct sunlight such as India and other tropical climates, concentrator photovoltaics (CP Vs) are necessary to improve the efficiency of solar energy and make the system cost-effective as well. CPVs use various types of lenses or mirrors such as the Fresnel lens to focus sunlight onto a smaller area of high- efficiency solar cells, thereby reducing the amount of expensive solar cell material needed.

[0011] In terrestrial applications, these MJ solar cells are currently being utilized in concentrator photovoltaics (CPV) modules. These CPV modules are mounted on a precision 2-axis solar tracking device which continuously tracks the position of the sun and orients CPV module at a normal angle to the solar rays. Generally, Refractive Fresnel lens(es) of the CPV module is(are) used to concentrate sun rays from a wider aperture area onto a small expensive MJ solar cell(s), leading to the generation of electricity. However, these CPV devices are lagging behind the other photovoltaics due to various problems such as heat dissipation, optical losses, environmental factors such as dust and temperature as well as commercial viability issues.

[0012] The US patent application US2019071189A1 to Donald Bennett Hilliard, discloses thin-walled conical structures with a concentrator for providing high- concentration for irradiation of high-temperature solar-thermal receiver tubes. A photovoltaic (PV) module includes multiple multijunction photovoltaic (MJPV) arrays arranged on a faceted cylinder. However, this application includes two inverted frustum shaped concentration structures that require to be secured together for concentration with a heat mirror mechanism.

[0013] The US patent application US20090250095A1, to Brent Perry Thorley, et al; describes a low profile solar tracking module that includes a non-shadowing lens. This lens includes multiple prisms that provide uniform light distribution. However, this patent application fails to reduce the requirement of MJ solar cell as that of the present invention.

[0014] The Korean patent application KR20170142638A, to Oh Hyung Hee, describes a solar photovoltaic concentrator device that includes a Fresnel lens condensing unit that is dome shaped. However, this patent application focuses on concentration of light and fails to reduce the requirement of MJ solar cell as that of the present invention.

[0015] The currently available photovoltaics have disadvantages of being bulky, due to high focal length of the lenses. Further, the photovoltaics in the prior art are less energy efficient and have high costs leading to commercial viability issues.

[0016] Therefore, there is a need for a cost-efficient optical concentration device for CPVs that increases the efficiency of energy generation while reducing semiconductor requirement and reducing thickness of CPV module.

[0017] SUMMARY OF THE INVENTION:

[0018] The present invention discloses a multi -axis torus ring segmented ellipsoid optical concentration device for concentrator photovoltaic (CPV) modules, including a primary optical element (POE) that has an outer planar surface and an inner surface, the inner surface is formed of a plurality of torus ring segments arranged along independent axes with varying radii, slope angles, and draft angles. The said arrangement collectively defines a continuous ellipsoidal refractive profile that simultaneously reducing focal length and increasing concentration ratio of incident solar rays. The present invention also includes a secondary optical element (SOE) being positioned at the reduced focal length of the POE, the SOE being a spherical cap enclosing a multi-junction solar cell and configured to receive and redistribute refracted rays from the POE allowing widening the acceptance angle and stabilize optical efficiency under varying incidence angles. Further, the present invention includes a multi-junction solar cell that is positioned within the SOE to receive concentrated solar rays, thereby enabling high optical efficiency with reduced semiconductor area usage; wherein the synergistic interaction between the torus ring segmented ellipsoidal POE and the SOE provides an optical efficiency of >90% at normal incidence and maintains >85% efficiency at an incident angle of 0.8°. This achieves improved energy generation, reduced cost, and compact CPV module design that is not attainable by a mere aggregation of conventional optical elements.

[0019] The plurality of torus ring segments (204) of the present invention include different radii, slope angles, and draft angles and are arranged along independent axes thereby defining an ellipsoidal refractive profile providing multiple focal points converging at the secondary optical element. Further, the secondary optical element (SOE) is a crescent-shaped spherical cap that encloses the multi -junction cell thereby widening the acceptance angle and stabilising optical efficiency under tracking misalignment of up to 0.8°. Furthermore, the torus ring segments (204) are configured to reduce the focal length to less than 70 mm while maintaining a concentration ratio of at least 1600x.

[0020] The device has an optical efficiency of at least 91% at normal incidence (0°) and at least 85% at 0.8° incidence angle and the the Concentration Acceptance Product (CAP) of the device is at least 0.8, thereby providing higher reliability of energy generation in practical conditions. Further, the device has a f-number is less than 0.6, thereby reducing the thickness and cost of the CPV module. Further, the the primary optical element (POE) and the secondary optical element (SOE) are fabricated from glass, polymethyl methacrylate (PMMA), or equivalent optically transparent material.

[0021] The multi -junction cell of the present invention occupies less than 0.1% of the total aperture area, thereby reducing semiconductor usage and device cost. Further, the POE is arcuate and concave with an approximate height of 122.15 mm and diameter of 31.77 mm, and the SOE has an approximate height of 6 mm and diameter of 10.96 mm. Furthermore, the combination of POE and SOE enabling uniform illumination distribution across the multi -junction cell by generating multiple focal endpoints on the target area.

[0022] The POE of the present invention includes an aperture being covered by torus ring segments and an aperture point is visible from the outer surface of the POE defining an angular concentration axis of the POE. Further, the SOE is positioned concentrically away from the POE, particularly on the focal length of the POE, leading to maximal targeted delivery of the refracted solar rays. The torus ring segments reduce the focal length of the POE, thereby leading to incidence of the refracted solar rays onto the SOE at a closer distance. The approximate height and diameter of the POE is 122.15mm and 31.77 mm respectively and the approximate height and diameter of the SOE is 6mm and 10.96mm respectively. A method of concentrating solar radiation in a concentrator photovoltaic (CPV) module using a multi-axis torus ring segmented ellipsoid optical concentration device (100), the method includes various steps. First step including providing a primary optical element (POE) having a planar outer surface and an inner surface formed by a plurality of torus ring segments arranged along independent axes with varying radii and slope angles to define an ellipsoidal refractive profile. Second step including positioning a secondary optical element (SOE) at a reduced focal length of the POE, the SOE being a spherical cap configured to enclose a multi-junction cell (112). Third step of receiving incident solar rays on the planar outer surface of the POE. Fourth step of refracting and concentrating the received solar rays through the torus ring segmented inner surface of the POE to generate multiple focal endpoints at the SOE. Fifth step of redistributing the concentrated rays by the SOE across an increased acceptance angle while maintaining reduced focal length a last step of directing the redistributed rays onto the multi -junction cell, thereby generating electrical energy with an optical efficiency of at least 90% at normal incidence and at least 85% at an incidence angle of 0.8°.

[0023] A method of manufacturing a primary optical element (POE) for device (100) for concentrator photovoltaic (CPV) modules, the method including various steps. A first step of defining an ellipsoidal profile of the POE based on a predetermined focal length and concentration ratio. A second step of generating a plurality of torus ring segments with independent axes and varying radii, slope angles, and draft angles, the ratio between major and minor radii being selected to achieve a required aspect ratio. A third step of superimposing the torus ring segments onto an inner surface of the POE using methods selected from geometric transformation, parametric modeling, or computer-aided design (CAD) techniques, so as to form a continuous refractive ellipsoidal surface. A fourth step of forming an outer planar surface of the POE for receiving incident solar rays. A fifth step of trimming and polishing excess material to remove non-functional portions while preserving the concentration behavior of the torus ring segments; and a final step of fabricating the POE from an optically transparent material selected from glass, polymethyl methacrylate (PMMA), or equivalent material, thereby producing a lightweight and efficient primary optical element for integration into the device.

[0024] BRIEF DESCRIPTION OF DRAWINGS:

[0025] The objectives and advantages of the present invention will become apparent from the following description read in accordance with the accompanying drawings wherein,

[0026] FIG. A shows a prior art of a photovoltaic concentrator with an optical stepped lens; FIG. 1 shows a perspective view of a multi-axis torus ring segmented ellipsoid optical concentration device for CPV module in accordance with the present invention;

[0027] FIG. 2 shows a front perspective view of a primary optical element of the multiaxis torus ring segmented ellipsoid optical concentration device for CPV module of FIG. l; FIG. 3 shows a cross-sectional view of the primary optical element of the multiaxis torus ring segmented ellipsoid optical concentration device for CPV module of FIG. 1;

[0028] FIG. 4 shows a side view of the primary optical element of the multi-axis torus ring segmented ellipsoid optical concentration device for CPV module of FIG. 1;

[0029] FIG. 5 shows a perspective view of a secondary optical element of the multi-axis torus ring segmented ellipsoid optical concentration device for CPV module of FIG. 1;

[0030] FIG. 6 shows a sectional view of the secondary optical element of the multi-axis torus ring segmented ellipsoid optical concentration device for CPV module of FIG. 1; and

[0031] FIG. 7 shows a graph of optical efficiency against incidence angle of primary optical element and that of a combination of primary optical element and secondary optical element (112) in accordance with the present invention.

[0032] DESCRIPTION OF THE INVENTION:

[0033] References in the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.

[0034] References in the specification to “preferred embodiment” means that a particular feature, structure, characteristic, or function described in detail thereby omitting known constructions and functions for clear description of the present invention.

[0035] The foregoing description of specific embodiments of the present invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed and obviously many modifications and variations are possible in light of the above teaching.

[0036] The terminology used below is to be interpreted in its broadest reasonable manner, even though it is being used in conjunction with a detailed description of certain specific examples of the disclosure. Indeed, certain terms may even be emphasized below; however, any terminology intended to be interpreted in any restricted manner will be overtly and specifically defined as such in this Detailed Description section.

[0037] Optical efficiency (no): The optical efficiency is the ratio of the solar radiation flux that reaches the absorber to the incoming solar power that hits the collector's aperture area.

[0038] Concentration Ratio (C): The Concentration Ratio (C) is the ratio of the collector aperture area to the receiver area.

[0039] Incident angle (I): Angle between Normal to the CPV module and the angle of incident solar rays is referred as Incident angle (I). Ideally, I should be 0°.

[0040] Acceptance angle (a): Acceptance angle is the incident angle at which optical efficiency is typically 90% of its maximum value (or optical efficiency at incident angle of 0°). Focal length (f): Focal length is the distance from the first surface of the lens where sun light impinges to the receiver plane where the effective concentration ratio is maximum.

[0041] F-number: is the ratio of the focal length of the lens to the aperture diameter of the lens. A low f-number means a larger maximum aperture also called a fast lens which results in a higher light collecting ability.

[0042] CAP (Concentration Acceptance Product \C sin(a) - Product of square root of Concentration Ratio and sine of Acceptance Angle

[0043] FIG. A illustrates a prior art photovoltaic concentrator as described in European Patent Application No. EP2519978B1. The prior art device includes at least one solar cell and an operating device comprising an optical stepped lens. The stepped lens has a smooth front surface for receiving solar radiation and a rear surface with a stepped profile formed of multiple stepped structures. In crosssection, the slope portion between the first and second intercept points within each step defines a focalization region, thereby altering the focal length of the device. However, this prior art does not disclose or suggest an arcuate, torus ring segmented ellipsoidal primary optical element as in the present invention, which simultaneously reduces focal length and increases concentration ratio to achieve higher optical efficiency.

[0044] Referring to FIG. 1, a perspective view of the multi -axis torus ring segmented ellipsoid optical concentration device for a CPV module, hereinafter referred to as device (100), is shown. The device (100) includes a primary optical element (POE) (104), a secondary optical element (SOE) (108), and a multi - junction cell (112). The POE (104), positioned as the outermost element, includes an outer surface (116) for receiving incident solar rays (124) and an inner surface (120) configured with torus ring segments.

[0045] The incident solar rays (124) impinge upon the outer surface (116) of the POE (104) and are refracted through its inner surface (120). The refracted rays are then directed onto the SOE (108), which further concentrates and redistributes the light onto the multi -junction cell (112) for energy conversion.

[0046] The multi -junction cell (112) is positioned beneath the secondary optical element (SOE) (108), with the SOE (108) enclosing the cell. The SOE (108) is radially aligned along the X-axis relative to the primary optical element (POE) (104) and is concentrically spaced from the POE (104). The POE (104) thus encloses the SOE (108) at a defined distance. The SOE (108) is located substantially at the focal length of the refracted solar rays produced by the POE (104). The spacing between the POE (104) and SOE (108) may vary depending on factors such as the degree of refraction of incident rays, the curvature of the POE (104), or other optical design parameters.

[0047] The primary optical element (POE) (104) is preferably arcuate in shape, while the secondary optical element (SOE) (108) is preferably dome-shaped. Both the POE (104) and SOE (108) are fabricated from optically transparent materials such as glass, polymethyl methacrylate (PMMA), or equivalent alternatives. A person skilled in the art will recognize that other suitable materials may also be employed without departing from the scope of the invention. In operation, incident solar rays (124) impinge upon the outer surface (116) of the POE (104), are refracted and concentrated, and are subsequently directed onto the SOE (108). Together, the POE (104), SOE (108), and multi -junction cell (112) constitute the device (100).

[0048] Referring to FIGS. 3 and 4, the primary optical element (POE) (104) is shown. The POE (104) includes a plurality of torus ring segments (204) superimposed onto its inner surface (120). A torus, in general, is a surface generated by the revolution of a circle about an axis in three-dimensional space, and may exist in forms such as ring torus, horn torus, or spindle torus. In the present invention, the torus ring segments (204) are arranged with independent axes and superimposed upon one another to define the inner surface (120) of the POE (104). Each segment (204) includes facets with different slope and draft angles, which collectively form a continuous ellipsoidal refractive profile.

[0049] The torus ring segments (204) are superimposed sequentially so as to cover the entire aperture (208) of the primary optical element (POE) (104), thereby forming a continuous and smooth optical surface. Each segment (204) is defined by a major radius and a minor radius, with variations in radii, draft angles, and slope angles across different segments. The ratio between the major and minor radii establishes the aspect ratio of each segment, which in turn governs its shape. In alternative embodiments, the aspect ratio may be varied to produce different configurations of the POE (104), such as flat or circular optical profiles, depending on the intended application.

[0050] The torus ring segments (204) are arranged on the inner surface (120) of the primary optical element (POE) (104), while the outer surface (116) of the POE (104) is substantially planar to facilitate efficient reception of incident solar rays (124). The segmented arrangement on the inner surface (120) maximizes concentration of refracted rays onto the target area of the secondary optical element (SOE) (108), thereby increasing the Concentration Acceptance Product (CAP) and reducing the f-number.

[0051] This combination enhances illumination uniformity, raises the concentration ratio, and decreases the required semiconductor area. Furthermore, the segmented structure reduces the focal length of the device (100), enabling solar rays (124) to be focused more effectively onto the SOE (108), which results in higher energy generation and reduced cost of the CPV module.

[0052] Referring to FIGS. 3 to 5, the formation of the primary optical element (POE) (104) is described. In a first step, a plurality of torus ring segments (204) are superimposed onto the inner surface (120) of the POE (104). The superimposition may be carried out using methods such as geometric transformation, parametric modeling, or specialized optical modeling techniques. Geometric transformation may involve translating a torus segment to the desired location on the POE, rotating the segment about an axis, and scaling it to conform to the curvature of the POE.

[0053] In another approach, parametric modeling may be employed, wherein torus segments are defined by equations in terms of angular parameters and then mapped to the inner surface (120). Alternatively, specialized techniques such as computer- aided design (CAD) software, finite element analysis (FEA) tools, or additive manufacturing processes such as 3D printing may be used to generate and superimpose the torus segments onto the POE (104). The next step includes positioning of multiple torus ring segments as per an angular concentration axis drawn between outer aperture point (208) on the outer ellipsoid and point on the target. A next step includes drawing an ellipsoid by connecting tangents of the torus ring segments (204). In a next step, torus ring segments (204) are superimposed till the aperture on the POE (104) is covered and a smooth finish is achieved. In a final step, facets are cut and remaining material is chopped out to save optical material while at the same time demonstrating concentration behaviour. Each torus ring cut would become a torus segment. All of such torus segments put together would result in ellipsoid.

[0054] In accordance with the present invention, the POE (104) is a curved and concave ellipsoid structure that concentrates solar rays (124) onto the multi - junction cell (124) maximally. However, other embodiments of the present invention may include POE of different shapes such as a flat configuration, a curved configuration and the like. In the present embodiment of the present invention, the approximate height of the POE (104) is 122.15mm and the approximate diameter of POE (104) is 31.77mm. Further, the approximate height of the SOE (108) is 6mm and the approximate diameter of SOE (108) is 10 / 96mm.

[0055] Now referring to FIGS.5 and 6, the secondary optical element (SOE)(108) of the present invention is described. The cross-sectional view of secondary optical element (SOE)(108) is an approximate crescent shape that encloses the multi- junctional cell (112). In accordance with the present invention, the multi -junction cell (112) is positioned below the SOE (112) placed below it. It is noted that the solar rays (124) that are refracted from the primary optical element (POE) (104) are received onto the secondary optical element (SOE) (108) at an increased concentration ratio and increased CAP with increased acceptance angles.

[0056] Now referring to FIG. 5 and 6, the formation of the SOE (108) is described. In a first step, a hollow spherical cap of a selected material such as glass, polymethyl methacrylate (PMMA) or the like is produced through conventional means. In a next step, the spherical cap is cut by a spherical cap of a larger radius by methods such as conventional cutting, CNC machining and the like. The radii of the cut made onto the hollow spherical cap is such that a multi -junction cell (112) is positionable within the hollow spherical cap. In a final step, the hollow spherical cap is positioned onto the selected multi -junction cell (112).

[0057] Now referring to FIG. 1 to 6, the assembly of the device (100) is described. In a first step, the torus ring segments (204) are superimposed onto the POE (104). In a next step, the SOE (108) is positioned at the predefined focal length of the device (100). In a next step, the multi -junction cell (112) is positioned within the SOE (108) such that the SOE (108) encloses the multi -junction cell (112).

[0058] In accordance with the preferred embodiment, the concentration ratio is 1600x and the optical efficiency of the POE is approximately 91.91%. Further, the optical efficiency of the whole device is approximately 91.13% at an incident angle of 0 degrees. Further, the focal length of the device from the centre of the POE.is approximately 66.2. Furthermore, lens height of POE from the bottom of the lens surface is approximately 31.77mm. , the device (100) includes a combination of primary optical element and secondary optical element. In accordance with another embodiment of the present invention, the device (100) includes a primary optical element solely. In this embodiment, there is a single concentrator element POE. In another embodiment of the present invention, the POE was flat and not curved such that the concentration ratio is 111 lx and the optical efficiency for POE is approximately 93.96 %. In this particular embodiment, the total optical efficiency of the device is approximately 90.62 % and has an incident angle of 0 degrees. Further, in this embodiment, the focal length of the device is approximately 98.4mm and the f-number is 0.695 and the lens height is approximately 4.42mm.

[0059] In accordance with another embodiment of the present invention, the device (100) includes a POE that is flat and not curved such that the concentration ratio is 1600x and the optical efficiency for POE is approximately 91.02 %. In this particular embodiment, the total optical efficiency of the device is approximately 86.98 % and has an incident angle of 0 degrees. Further, in this embodiment, the focal length of the device is approximately 87.8mm and the f-number is 0.517 and the lens height is approximately 6.22mm.

[0060] In yet another embodiment of the present invention, the device (100) includes POE that is flat and not curved such that the concentration ratio is 1600x and the optical efficiency for POE is approximately 88.71 % at an incident angle of 0 degrees. Further, in this embodiment, the focal length of the device is approximately 125.0mm and the f-number is 0.736 and the lens height is approximately 2.93mm. FIG. 4 is a graphical illustration of the comparison of the optical efficiency obtained by the combination of primary optical element and secondary optical element in accordance with the first embodiment of the present invention; versus the optical efficiency obtained from primary optical element solely in accordance with the second embodiment of the present invention. The graph demonstrates optical efficiency along the X axis and the incident angle of the solar rays along the Y axis.

[0061] When the solar rays are incident on the primary optical element, they are expected to be normal to the POE. However, depending on the conditions of the tracking device or any other practical conditions, there could be a slight variation in the incident angle of the solar rays with respect to the POE. This variation leads to a difference in the optical efficiency. FIG. 4 demonstrates a steep decline in the optical efficiency when the primary optical element is employed solely in accordance with the second embodiment. However, the optical efficiency declines gradually when a combination of primary optical element and secondary optical element in accordance with the first embodiment is employed, and shows a steady decline for longer range of the variation in the incidence angle. Further, Fig. 4 shows a wider angle of acceptance of the variation in the incidence angle while maintaining optical efficiency.

[0062] It is noted that Fig. 4 demonstrates that at 0° incident angle, the optical efficiency of the device (100) is 91.13%. Further, at 0.8° incident angle, the optical efficiency of the device (100) in accordance with the first embodiment is 87%; and at 0.8° incident angle, the optical efficiency of device in accordance with the second embodiment is 44%. Also, the focal length of the lens of the device of the present invention is 66.2 + 30.77 mm.

[0063] In the preferred embodiment, the present invention includes the primary optical element and secondary optical element. From the graph, it is evident that the optical efficiency of the first embodiment that is the preferred embodiment is more than that of the second embodiment. As observed in the graph, the second embodiment is less efficient than that of the first embodiment.

[0064] TABLE 1 : Concentration ratio, Concentration Acceptance product (CAP) and f-number.

[0065] Table.1 describes the concentration ratio, Concentration Acceptance Product (CAP) and f-number of different embodiments of the present invention and that of the prior art. In accordance with the present invention, Concentration Ratio of the device (100) is high, the device therefore requires lesser Multi Junction cell usage, in turn leading to decreased capital cost of the CPV device. Furthermore, increased CAP means an increase in the Acceptance angle a, thus leading to a more reliable performance in practical conditions and more energy generation of the device. Lesser f-number leads to lesser thickness and reduced cost of the CPV module. As observed in Table 1, the Concentration ratio of the first embodiment and the second embodiment in accordance with the present invention is more than that of the prior art. Similarly, the CAP of both the embodiments is less than that of the prior art. It is to be noted that F-number of the present invention is less than that of the prior art. It is therefore evident that the embodiments of the present invention are more energy efficient, more reliable and more commercially viable than that of the prior art. Referring to FIGS 1 to 4, operational flow of the device in accordance with the present invention is described. In operation, the solar rays (124) are incident on the outer surface (116) of the POE (104). The received incident solar rays (124) are broad however, the multi-axis torus ring segments on the inner surface (120) of the POE (104) narrows the received solar rays (124) through refraction phenomenon. The POE (104) refracts the solar rays (124) at a reduced focal length so that the solar rays (124) are received on the SOE (108) that is positioned at a closer distance. Further, the received solar rays (124) are then transferred to the MJ cell (112) from the SOE (108). The MJ cell (112) then generates energy from the received solar rays. Further, as the concentration ratio of the incident light is more, the energy generated is more, making the device (100) energy efficient.

[0066] The device (100) of the present invention advantageously minimizes the Cost to energy ratio of Concentrated Photovoltaic devices. Further, the device (100) advantageously increases the solar efficiency leading to increased energy generation. The device (100) is advantageously made from lesser amount of metals leading to a lighter Concentrated Photovoltaic device (CPV) module that may be easily cleaned manually. Furthermore, the device (100) advantageously includes a semi-conductor area of only 0.06% and the remaining material used is either metal or glass. This advantageously allows for easy recycling of technology after the End of Life (EOL).

[0067] The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, to thereby enable others, skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated.

[0068] It is understood that various omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the scope of the present invention.

Claims

CLAIMS:

1. A multi-axis torus ring segmented ellipsoid optical concentration device(100) for concentrator photovoltaic (CPV) modules, comprising: a primary optical element (POE) (104) having an outer planar surface (116) and an inner surface (120), the inner surface being formed of a plurality of torus ring segments (204) arranged along independent axes with varying radii, slope angles, and draft angles, the said arrangement collectively defining a continuous ellipsoidal refractive profile that simultaneously reducing focal length and increasing concentration ratio of incident solar rays (124); a secondary optical element (SOE) (108) being positioned at the reduced focal length of the POE (104), the SOE being a spherical cap enclosing a multi -junction solar cell (112) and configured to receive and redistribute refracted rays from the POE (104) allowing widening the acceptance angle and stabilize optical efficiency under varying incidence angles; and the multi -junction solar cell (112) being positioned within the SOE (108) to receive concentrated solar rays (124), thereby enabling high optical efficiency with reduced semiconductor area usage; wherein the synergistic interaction between the torus ring segmented ellipsoidal POE (104) and the SOE (108) provides an optical efficiency of >90% at normal incidence and maintains >85% efficiency at an incident angle of 0.8°, thereby achieving improved energy generation, reduced cost, and compact CPV moduledesign not attainable by a mere aggregation of conventional optical elements.

2. The device (100) as claimed in claim 1, wherein the plurality of torus ring segments (204) including different radii, slope angles, and draft angles and being arranged along independent axes thereby defining an ellipsoidal refractive profile providing multiple focal points converging at the secondary optical element (108).

3. The device (100) as claimed in claim 1, wherein the secondary optical element (SOE) (108) being a crescent-shaped spherical cap enclosing the multi -junction cell (112) thereby widening the acceptance angle and stabilising optical efficiency under tracking misalignment of up to 0.8°.

4. The device (100) as claimed in claim 1, wherein the torus ring segments (204) being configured to reduce the focal length to less than 70 mm while maintaining a concentration ratio of at least 1600x.

5. The device (100) as claimed in claim 1 having an optical efficiency of at least 91% at normal incidence (0°) and at least 85% at 0.8° incidence angle.

6. The device (100) as claimed in claim 1, wherein the Concentration Acceptance Product (CAP) of the device is at least 0.8, thereby providing higher reliability of energy generation in practical conditions.

7. The device (100) as claimed in claim 1, wherein the f-number is less than 0.6, thereby reducing the thickness and cost of the CPV module.

8. The device (100) as claimed in claim 1, wherein the primary optical element (POE) (104) and the secondary optical element (SOE) (108) beingfabricated from glass, polymethyl methacrylate (PMMA), or equivalent optically transparent material.

9. The device (100) as claimed in claim 1, wherein the multi -junction cell (112) occupying less than 0.1% of the total aperture area, thereby reducing semiconductor usage and device cost.

10. The device (100) as claimed in claim 1, wherein the POE (104) being arcuate and concave with an approximate height of 122.15 mm and diameter of 31.77 mm, and the SOE (108) having an approximate height of 6 mm and diameter of 10.96 mm.

11. The device (100) as claimed in claim 1, wherein the combination of POE (104) and SOE (108) enabling uniform illumination distribution across the multi -junction cell (112) by generating multiple focal endpoints on the target area.

12. The device (100) as claimed in claim 1 wherein, the POE (104) including an aperture being covered by torus ring segments and an aperture point (208) being visible from the outer surface (116) of the POE (104) defining an angular concentration axis of the POE (104).

13. The device (100) as claimed in claim 1 wherein, the SOE (108) being positioned concentrically away from the POE (104), particularly on the focal length of the POE (104), leading to maximal targeted delivery of the refracted solar rays (124).

14. The device (100) as claimed in claim 1 wherein, the torus ring segments (204) reducing the focal length of the POE (104), thereby leading toincidence of the refracted solar rays (124) onto the SOE (108) at a closer distance.

15. The device (100) as claimed in claim 1 wherein, the approximate height and diameter of the POE (104) being 122.15mm and 31.77 mm respectively and the approximate height and diameter of the SOE (108) being 6mm and 10.96mm respectively.

16. A method of concentrating solar radiation in a concentrator photovoltaic (CPV) module using a multi-axis torus ring segmented ellipsoid optical concentration device (100), the method comprising the steps of: a. providing a primary optical element (POE) (104) having a planar outer surface (116) and an inner surface (120) formed by a plurality of torus ring segments (204) arranged along independent axes with varying radii and slope angles to define an ellipsoidal refractive profile; b. positioning a secondary optical element (SOE) (108) at a reduced focal length of the POE (104), the SOE (108) being a spherical cap configured to enclose a multi -junction cell (112); c. receiving incident solar rays (124) on the planar outer surface (116) of the POE (104); d. refracting and concentrating the received solar rays (124) through the torus ring segmented inner surface (120) of the POE (104) to generate multiple focal endpoints at the SOE (108);e. redistributing the concentrated rays by the SOE (108) across an increased acceptance angle while maintaining reduced focal length; and f. directing the redistributed rays onto the multi -junction cell (112), thereby generating electrical energy with an optical efficiency of at least 90% at normal incidence and at least 85% at an incidence angle of 0.8°.

17. A method of manufacturing a primary optical element (POE) (104) for a multi-axis torus ring segmented ellipsoid optical concentration device (100) for concentrator photovoltaic (CPV) modules, the method comprising the steps of: a. defining an ellipsoidal profile of the POE (104) based on a predetermined focal length and concentration ratio; b. generating a plurality of torus ring segments (204) with independent axes and varying radii, slope angles, and draft angles, the ratio between major and minor radii being selected to achieve a required aspect ratio; c. superimposing the torus ring segments (204) onto an inner surface (120) of the POE (104) using methods selected from geometric transformation, parametric modeling, or computer-aided design (CAD) techniques, so as to form a continuous refractive ellipsoidal surface;d. forming an outer planar surface (116) of the POE (104) for receiving incident solar rays (124); e. trimming and polishing excess material to remove non-functional portions while preserving the concentration behavior of the torus ring segments (204); and f. fabricating the POE (104) from an optically transparent material selected from glass, polymethyl methacrylate (PMMA), or equivalent material, thereby producing a lightweight and efficient primary optical element for integration into the device (100).

Images