KR20150048841A - Photovoltaic system including light trapping filtered optical module - Google Patents

Abstract

The present invention relates to a photoregulated dielectric slab having a first side and a second side; A first battery adjacent to the first surface of the slab, the first battery having a bandgap of energy lower than the absorption start energy of the dielectric slab; At least one filter component in optical contact with a second surface of the dielectric slab; And a sub-cell array comprising a plurality of photovoltaic cell sub-cells, wherein at least one of the sub-cells comprises a first side in optical contact with the at least one filter component, And more particularly to a photovoltaic system for converting incident light into electrical energy, including a light trapping optical module including a light trapping optical module.

Description

TECHNICAL FIELD [0001] The present invention relates to a photovoltaic system including a light trapping and filtering optical module,

The present invention relates to a photovoltaic device for converting incident light into electrical energy. More specifically, the invention relates to a photoelectric device comprising a light trapping optical module comprising a dielectric slab connected to a sub-cell array.

preference

This patent application is a continuation-in-part of US Provisional Patent Application No. 61 / 695,216 filed on August 30, 2012 entitled " Optical Element for Full Spectrum, Ultra High Efficiency Solar Energy Conversion & Filed on January 25, 2013, entitled " Photovoltaic System Including Modules, " filed on January 25,2003, which is incorporated herein by reference in its entirety.

Photovoltaic cells, which may also be referred to as solar cells or PV cells, are useful for converting incident light such as sunlight into electrical energy. Such cells can be provided, for example, as a single junction cell, which typically provides a specifically defined bandgap with essentially low conversion efficiency. This is because only photons having energy higher than the single band gap of the cell can be used to produce useful work and essentially all of the energy of the photons greater than the bandgap of the cell is thermally neutralized by heat thermalize). Thus, a single junction is photoelectrically responsive to only a portion of the spectrum, and is not very efficient for most of the wavelengths it reacts to. Therefore, many methods for increasing the efficiency of solar cells have been used and proposed.

One common method used to achieve higher photovoltaic efficiency is to provide sunlight to multiple junction solar cells rather than single junction solar cells. The multi-junction cell allows higher energy photons to be converted by a cell having a higher band gap, thereby allowing the intermediate wavelength to go to a cell having an intermediate band gap while minimizing thermal neutronization. Multijunction cells expand the overall spectral response by providing a lower bottom junction in terms of energy than the best single junction cell provides. Such a multi-junction solar cell is composed of a specific semiconductor material whose band gap energy is selected to encompass the solar spectrum. Photons with energies greater than the highest band gap are first collected by the highest energy gap sub-cell. The lower energy photons pass through the highest energy band gap sub-cell and then to the sub-cell with the highest energy band gap. This pattern continues to a sub-cell having the lowest energy bandgap. In this way, the energy of the absorbed photons, which is greater than the bandgap of the absorbing cell, which is the energy that is thermally neutronized and lost as heat, is minimized. In addition, a greater number of band gaps generally means that, when optimized, a larger portion of the total solar spectrum can be absorbed by the multiple junction cell compared to a single junction cell.

Although multiple junction solar cells provide advantages over single junction solar cells, additional efficiency improvements can be achieved through the use of a photomultiplier optical product that is used to split incident solar light and direct the light to a different solar cell. Narrower bands of light are directed to sub-cells having different band gaps, and / or to multiple junction cells having different sets of band gaps. Each targeted sub-cell is designed to have a bandgap tailored to the excitation spectrum to assist in optimizing energy conversion. That is, the split optical element divides incident light into segments or slices, and then allows the slices to independently point toward a photovoltaic sub-cell having an appropriate bandgap.

Photovoltaic systems using spectrally-split optical elements to improve solar conversion efficiency are described in the patent and technical literature. Examples include U.S. Patent Application Publication No. 2011/0284054 (Wanlass); Gu, et al., Renewable Energy and Environment Technical Digest, "Common-Plane Spectrum-Splitting Concentrating Photovoltaic Module Design and Development," 1-3 (2011); Imenes et al., "Solar Energy Materials and Solar Cells," Spectral Beam Splitting Technology for Increased Conversion Efficiency in Solar Concentrating Systems, A Review, 84: 19-69 (2004); Optics Express, "Organic Photovoltaic Cell in Lateral-Tandem Configuration Employing Continuously-Tuned Microcavity Sub-Cells," 16 (24) 19987-19994 (2008); Solar Energy Materials and Solar Cells, "Light Trapping, a New Approach to Spectrum Splitting," 92 (12) 1570-1578 (2008); And Peters (Ian Marius, "Photonic Concepts for Solar Cells" (2009), Dissertation, Fraunhofer Institute for Solar Energy Systems).

A photovoltaic system using a solar cell spectral resolution technique improves the conversion efficiency of incident light into electrical energy, but there is a continuing need to provide a system that allows for higher efficiency.

The present invention relates to a photovoltaic system for converting incident light into electrical energy, which may be referred to as a light trapping and collecting device. Such a system can be used to improve the performance of a solar cell to achieve higher conversion efficiency. Embodiments of the present invention generally include an optical capture optical module having a plurality of photovoltaic sub-cells arranged in an array, and a dielectric slab for capturing incident light and transporting the captured light to the photovoltaic sub-cells. The dielectric slab is composed of a material having a relatively high refractive index, for example at a wavelength of 550 nm, such as above 2.0. In addition, there is provided a filter element or array that may be patterned or deposited on the bottom of the dielectric slab, and the sub-cells may be attached to such a filter element or array. In other words, the slab bottom can be configured in a specific manner to act as a filter. Alternatively, the filter component or array may be formed on or grown on top of the sub-cell. In any case, the filter component is disposed between the plurality of sub-cells and the dielectric slab, so that the light can be filtered as desired before the light reaches the sub-cell. The filter component may be a photonic crystal that may be patterned on the bottom surface of the slab in one or more dimensions. In one example, the photonic crystal may be patterned in three dimensions to provide interference in all directions. The optical capture optical module may include an antireflective coating on the top surface of the battery and / or dielectric slab disposed over the dielectric slab.

The light is randomized inside the dielectric slab and can be scattered in all directions. Randomization can occur on the top side of the slab and / or inside the slab material itself. The sub-cell of the system may be a single junction or multiple junction cell, for example a triple junction cell. In an embodiment of the present invention, multiple sub-cells for a system include a first group of sub-cells having a first set of band gaps and a second group of sub-cells having a second set of band gaps And the filter array includes first and second filter regions corresponding to the first and second groups of sub-cells, respectively. In an exemplary embodiment, the first and second filter regions are arranged in a pattern of an oblong plate type so that the first set of sub-cells is aligned with the first set of filters and the second set of sub- ≪ / RTI >

The photovoltaic system may optionally include an optical condensing module, which may include a single optical condensing component or multiple optical condensing components, wherein the system comprising multiple components is configured to condense at relatively high levels, May be arranged in series to provide modules. For example, the optical condensing module may comprise a combination of a Fresnel lens, which is a first optical element, and a compound parabolic concentrator, which is a second optical element. The output of the optical condensing module may be a relatively small perforation, for example it may be a relatively small perforation aligned with the area of the optical capturing optical module that accommodates this output.

In one specific embodiment, a photovoltaic system is provided for converting incident light into electrical energy. The system includes a light capturing optical module comprising a photoregulated dielectric slab having a first side and a second side, and a first battery adjacent the first side of the dielectric slab, wherein the first cell is a dielectric slab And has a bandgap of energy lower than the energy of initiation of absorption. The system further includes a sub-cell array comprising one or more filter components and a plurality of photovoltaic sub-cells in optical contact with a second side of the dielectric slab, wherein one or more of the sub- And a first surface in optical contact with the filter component.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be further elucidated with reference to the accompanying drawings, wherein like structure throughout the several figures are represented by like numerals.
1 is a perspective view of a portion of a photovoltaic system of the present invention, including an optical focusing component;
Figure 2 is an enlarged perspective view of a light trapping and filtering light concentrating device of the type shown with the optical focusing component of Figure 1;
Figure 3 is an enlarged perspective view of the photovoltaic cell of the type shown in Figure 2;
Fig. 4 is an enlarged perspective view of a light trapping and filtering light condensing device which does not include an upper absorption cell.
5 is a perspective view of a light trapping and filtering light concentrating device of the present invention which can be introduced into a printed circuit board.
6 is a three-dimensional graph showing a design space for maximizing optical efficiency with respect to the refractive index of the dielectric light trapping slab and the number of cells.
Fig. 7 is a graph showing the efficiency of an exemplary apparatus as a light collecting function, using the concept and apparatus of the present invention. Fig.

The embodiments of the present invention described below do not intend to limit or complete the present invention in the specific form disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may understand and appreciate the principles and practice of the invention. All patents, pending patent applications, patent publications, and technical literature cited throughout this specification are herein incorporated by reference in their entirety for all purposes.

Referring to the drawings, there is shown an exemplary embodiment of a photovoltaic system 10 of the present invention, first of all with reference to Figures 1 to 3, which generally includes an optional light focusing device or optical condensing module 12, Capture optical module 14. The system 12 can be used to photoelectrically convert incident light into electrical energy, as will be described in further detail below. If a light concentrator is provided, the system 10 may alternatively be referred to as a light trap filtration concentrator.

The optical module 14 can generally capture the light provided (e.g., by an optical condensing module or directly by the sun) and transport the light to a plurality of photovoltaic cells or sub-cells 22, 22 ' And a dielectric slab or layer (24). The sub-cells used herein may vary in their architectural aspects, but generally include a band that accepts light of a certain range of wavelengths from the optical spectrum-splitting or filtering component and matches a certain range of wavelengths affecting it Gaps, or a series of band gaps. In one example, the red wavelength is directed to a sub-cell having a bandgap optimized for red light, and the green wavelength is directed to a sub-cell optimized for green light. Filters can be selectively used in the case of bandgap cells, but can provide improved efficiency in accordance with parasitic absorption in the cell.

In an embodiment of the present invention, the sub-cells are in optical contact with the other side of the dielectric slab 24, while the top cell 26 is provided in contact with one side of the dielectric slab 24. [ In general, when the components of the module 14 are in optical contact with one another, they are in intimate physical contact, and preferably any spacing is much smaller than the wavelength of light, which is often referred to herein as an " operative contact Quot;). In any case, it may be desirable to use multiple layers of coating to minimize refraction index differences or spacing between various surfaces and / or reduce reflections.

One embodiment of the dielectric slab 24 is a solid material, such as GaP or titania, that is electrically non-conductive and has a high index of refraction (i.e., greater than 2.0 at 550 nm, or preferably greater than 3.0 at 550 nm) Other materials are also considered. In general, the material for the dielectric slab 24 is transparent to the wavelength of interest (i. E., A lower wavelength in terms of energy relative to the wavelength absorbed by the top cell and converted into electrical energy) over most of the sunlight spectrum Lt; RTI ID = 0.0 > refractive index. ≪ / RTI > This high index of refraction will assist in capturing the light introduced into the slab 24 before light is absorbed by one of the sub-cells. The dielectric slab 24 includes texturing on the top surface and / or the spawner within the slab to randomize the incident light so that the incident light is scattered in all directions. This texturing may be provided as a physical texture on the surface of the slab where the texture itself may be irregular or even more reflective, such as may be achieved with a microreplicated surface (e.g., an etched and micro-replicated surface) You can order - order. In addition to those specifically described herein, many types of structures and arrangements can be used to provide randomization of light.

The thickness of the dielectric slab may be selected to have characteristics that allow it to achieve certain performance characteristics. For example, it may be desirable to provide a slab having a thickness at least equal to the width of the sub-cells. In one example, the system includes a sub-cell of about 1 mm on each side, and a dielectric slab having a thickness of about 1 mm. For relatively thin slabs, the fraction of light rays striking the same cell type twice in a given row is relatively high compared to the thicker slab.

As described herein, optical efficiency is generally determined by dividing the number of photons that have passed through the spectral division component and deposited in a particular sub-cell by the total number of photons photons affecting the top layer of the optical capture optical module Lt; / RTI > The system efficiency can be characterized by the amount of electrical energy generated by the apparatus divided by the total amount of solar energy entering the apparatus. For example, under direct daylight illumination of 1000 W / m ² , the total efficiency of the device producing 500 W of electrical energy is 50%.

The top surface 20 of the dielectric slab 24 may be adjacent to the layer 25 and / or the adhesive layer that is the anti-reflection coating or layer provided so that incident light reaching the slab is not reflected from the slab 24. [ The slab 24 may further be on top of the top surface 20 to form a top or bottom portion 20 which may be light-absorbent, for example a 2.2 eV GaP battery and may be referred to as a "pre- 1 < / RTI > The refractive indices of the first battery 26 and the slab 24 allow the total internal reflection to trap the incident light in the slab 24 and the first battery 26, May have more than one effect on the filtered sub-cell prior to its introduction. It is to be understood that when the "first" and "top surface" are used for the battery 26, these terms are not intended to be limiting and that one or more additional layers may be provided on top or outside of such a cell. The use of the battery 26 with a dielectric slab results in a higher index of refraction of the slab 24 because at least some of the light (e.g., at least part of the blue light and UV light) will be absorbed. That is, at least a portion of the high-energy light otherwise absorbed by the slab is absorbed by the first or top cell 26 instead, so that it is not lost in the slab. Thus, in an embodiment of the present invention, the first or top cell 26 is positioned adjacent a first side of the dielectric slab, wherein the first or top cell 26 has a band gap , And absorption energy initiation occurs at the lowest energy (i.e., the longest wavelength) where there is significant absorption within the material. In general, absorption is considered significant if the absorption length of light in the material is less than ten times the thickness of the slab. The first or top cell 26 may further comprise a anti-reflection coating.

In a particular embodiment of the present invention, the first or top cell 26 is optimized to the blue portion of the spectrum because the efficiency of light trapping in the dielectric slab increases as the refractive index increases, Because the material generally tends to absorb this region, rather than being permeable to higher energy wavelengths, e.g. UV and blue light. Thus, if the blue / UV light is not absorbed by the first cell, it will be parasitically absorbed and lost in the slab. Using a high-energy light absorbing cell on top of the dielectric slab allows the blue light to be selectively converted to electricity before the remainder of the light enters the dielectric slab. In this way, higher total efficiency can be achieved by avoiding the parasitic absorption of blue / UV light with a high index of slab.

The first or upper cell 26 may be a single junction cell or a multiple junction cell. These cells 26 and sub-cells 22 and 22 'are stacked or otherwise attached to the dielectric slab 24 to minimize the number of interfaces between the cell and the slab. For example, if there is an air interface between the slab 24 and the sub-cells and / or the light absorbing cell, this can lead to optical loss due to unwanted reflections. One exemplary adhesive that such components may be used to adhere to one another is TiO ₂ Sol gel, which provides a relatively high index to avoid unwanted reflections at the interface.

The refractive index of the slab 24 is at least slightly susceptible to being lowered so that the parasitic energy of the higher energy wavelength in the slab 24 Absorption can be minimized or avoided. The system would be less efficient in terms of solar energy conversion, as compared to an arrangement comprising a first or top battery 26. This embodiment is shown in Fig. 4, which is provided with a structure similar to that of Fig. 3, because the refractive index of the slab 24 is limited due to the fact that some of the light is not absorbed before reaching the slab 24 May be lower.

Referring again to FIG. 2, when the top module 26 is mounted on the optical module 14, such a cell may be assembled in any number of ways, for example an adhesive layer 25 (e.g., a titania sol-gel adhesive) Or otherwise directly grown on top of the slab 24 as a monolithic structure. This adhesive layer 25, if used, preferably has a high index of refraction so that light can travel through it and reach the slab 24 relatively easily. In one embodiment, the first or top cell 26 may be a single junction solar cell, a photovoltaic cell, or a multiple junction cell.

In order to maximize the light trapping in the slab, an additional reflecting device may be provided on at least one side thereof. Alternatively, cells or cell stacks may be provided on one or more sides of the slab, with the sides preferably being fitted with filters for such an arrangement, wherein these filters are arranged on the side of the slab 24 and / May be provided as a patterned surface on the sub-cell.

The optical capture optical module 14 further includes a plurality of photovoltaic sub-cells 22, 22 ', each of which is tuned to photovoltaically absorb a predetermined subset of the optical spectrum. As shown, each of the sub-cells 22, 22 'may be a multi-junction solar cell or, more specifically, a tri-junction solar cell. As best shown in FIG. 3, the first cell stack 22 is disposed adjacent to the second cell stack 22 ', each cell stack having three Thereby providing six differently tuned photovoltaic cells for the entire system (if an upper cell is provided, this would provide the seventh photovoltaic cell of the system, which would be any of the other six cells Lt; / RTI > battery). In order to electrically isolate the cells, such as with an insulating material (e.g., a UV-cured dielectric polymer or functional equivalent) holding the cells in a spaced apart arrangement, A space may be provided between the first and second openings 22 '. In one embodiment, the cells are considered to be adjacent to each other, in terms of their close proximity to each other, while being substantially in electrical contact with one another. That is, the cells may be spaced apart from one another by a distance of between 1 m and 1 mm, or may be closer together, for example in the range of 1 to 100 m. Generally, each battery stack is designed to react most efficiently to a particular wavelength of light of the incident light towards it.

In the illustrated exemplary embodiment, the second battery stack 22 'includes a first contact grid 50, a first battery 52, a second battery 56, and a third battery 60, A first tunnel junction 54 between the first cell 52 and the second cell 56 and a second tunnel junction 54 between the second cell 56 and the third cell 60 58, and a rear contact point 62, respectively. The adjacent first electrical laminate 22 also includes a plurality of layers including a front contact grid 70, a first cell 72, a second cell 76, and a third cell 80, A first tunnel junction 74 between the first battery 72 and the second battery 76, a second tunnel junction 78 between the second battery 76 and the third battery 80, and a second tunnel junction 78 between the rear contact 82 ).

3, the first cell 52 of the second battery laminate 22 ', which is the top battery of such a laminate 22', has a thickness in the range of 670 nm to 564 nm (E. G., It has bandgap characteristics) to absorb a portion of the spectral bandwidth of the incident light including the wavelength, and may have a band gap of 1.85 eV. The spectral band width portion of the incident light that deviates from this wavelength range will move to the adjacent cell 56. The second battery 56 of the second battery laminate 22 ', which is the intermediate cell of this laminate 22', absorbs the spectral band width portion of the incident light including the wavelength in the range of 785 nm to 670 nm (E. G., It has bandgap characteristics) and will have a band gap of 1.58 eV. The spectral band width portion of the incident light that deviates from such a wavelength range will move to the adjacent battery 60. The third battery 60 of the second battery laminate 22 ', which is the lowest secondary battery of the stack 22', has a tuning ratio (a) to absorb the spectral band width portion of the incident light including the wavelength in the range of 898 nm to 785 nm (E. G., It has bandgap characteristics) and will have a 1.38 eV bandgap.

As discussed above, the first battery stack 22 is adjacent to the second battery stack 22 ', wherein the first cell 72 of the first battery stack 22 (such a stack 22) Is tuned to absorb the spectral band width portion of the incident light including the wavelength in the range of 1088 nm to 898 nm (for example, it has the band gap characteristic) and will have a 1.14 eV band gap . The spectral band width portion of the incident light outside such a wavelength range will move to the adjacent cell 76. The second cell 76 of the first battery laminate 22 (which is the intermediate cell of this laminate 22) absorbs the spectral band width portion of the incident light including the wavelength in the range of 1333 nm to 1088 nm (E. G., It has bandgap characteristics) and will have a 0.93 eV bandgap. The spectral band width portion of the incident light that deviates from such a wavelength range will move to the adjacent battery 80. The third battery 80 of the first battery laminate 22, which is the first battery, which is the lowest secondary battery of the laminate 22, has a spectral band width portion of the incident angle including the wavelength in the range of 1771 nm to 1333 nm (E. G., It has band gap characteristics) and may have a 0.70 eV band gap. The wavelength ranges and associated bandgaps described above are only intended to provide exemplary device arrangements and embodiments of the present invention may include a battery or stack of cells having characteristics that are at least slightly different from those of the described embodiments Should be understood.

The first battery or cell stack 22 may further include a bus bar 40 that may be provided for a cell having a relatively low bandgap and a second cell or stack of cells 22 ' And may include a bus bar 42 that may be provided for the battery. The isolated intersection point 44 is located at a point where the bus bars 40, 42 cross each other. Alternatively, other contact methods and arrangements can be used, for example non-intersecting isolated contacts to the back conductive path.

As shown, the sub-cells 22, 22 'are arranged in a pattern of an oversized or "chessboard" type across the length and width of the optical module 14. As shown in FIG. 2, the optical module 14 may include one or more filters 30 generally disposed between the dielectric slab 24 and the sub-cells 22, 22 '. This filter (s) 30 is provided to ensure that light is directed to the corrected sub-cells, where the light not directed to the corrected sub-cell must be reflected. In order to provide the desired filtration, the texturing slab may be equipped with filters of a wool pattern corresponding to and aligned with the cell array, so that the first set of sub- And the second set of sub-cells are aligned with the second set of filters. In an alternate arrangement, the observer pattern may be comprised of filters on a cell or stack of cells (e.g., a cell or stack of cells 22) having a relatively low bandgap, wherein a portion Photons will be parasitically absorbed by the battery or cell stack (e.g., cell stack 22 ') having a relatively high bandgap. In an embodiment of the photovoltaic system, adjacent cells of the orbital pattern are receptive to different wavelengths from the spectral splitter. This increases the likelihood that a photon with a desired wavelength will strike a particular sub-cell with only a minimal number of internal reflections within the dielectric slab 24. [ Filters may have a plurality of different embodiments, such as multilayer dielectric laminates, gratings, and photonic crystals, all of which may be completely periodic or not.

The filters used with module 14 may be, for example, two-dimensional or three-dimensional photonic crystal type filters, for example, they may be selected to achieve superior omindirectionality compared to a single- . While one-dimensional photonic crystals may achieve omnidirectional performance, such filters may be less efficient when light is incident on a high index material, for example in the case of the high index slab described herein, For example. Photonic crystals can have a variety of different structures and properties, but are generally composed of periodic dielectric nanostructures that affect the progression of electromagnetic waves by defining allowable and inhibited-electron energy bands, as described herein. In essence, photonic crystals contain regularly repeating internal regions of high dielectric constant and low dielectric constant. A photon (which behaves like a wavelength) may proceed through its structure, depending on its wavelength. The wavelengths of light allowed to be moved are known as modes, and groups of allowed modes can form bands. An unacceptable band of wavelengths is referred to as an optical band gap, which results in distinct optical phenomena, such as the inhibition of spontaneous emission, the altitude reflection of omni-directional mirrors, and low waveguide losses. Since the fundamental physical phenomenon is based on diffraction, the periodicity of the dielectric features and the photonic crystal structure is approximately the same length-scale as the electronic substrate in the photonic crystal material (i.e., 1/4 of the wavelength in the material for a one-dimensional photonic crystal mirror) Lt; / RTI >

Each of the photovoltaic cells of the module 14 may include a plurality of features, such as a center cell active area, a back contact and reflective device, one or more contact grid areas, a layer that may include an anti-reflective coating / filter, and / . Each photovoltaic cell has a bandgap characteristic that generally allows tuning or absorbing a particular spectral bandwidth of the incident light applied thereto, and it allows the reflection of the unabsorbed portion to be reflected at the top or bottom of the cell Device. During operation, the photocells are arranged such that the light entering and accumulating in each cell stack is absorbed and reflected from the highest energy to the lowest energy (e.g., blue is absorbed before green, and orange is absorbed before red do).

As described above, the optical module 14 has two different cell stacks, each of which includes three band gaps, so that if the first cell is not considered, six different solar cells are used in the module Are illustrated and described. However, more or less than two of these cell stacks may be provided for a particular optical module, where certain subsets of the optical spectrum that each cell absorbs and reflects may then be used for the six junction structures It will be different from the one described above. In addition, the wavelength range associated with each of the solar cells described above may be smaller or larger depending on the specific material used, the tuning of the system, and the location of the system.

One or more photovoltaic systems of the present invention may be fabricated from modules comprising a plurality of systems. The system itself and / or the modules in which it is included may again be mounted in a common framework, wherein the entire frame and / or individual modules may include tracking or non-tracking features, depending on the system and its desired performance have.

The relatively high efficiency that can be achieved by the photovoltaic system of the present invention occurs for a variety of reasons. For one reason, the solid material of the dielectric slab can provide improved efficiency in terms of optically coupling incident light to the solar cell, and randomizing the light can result in a top-level cell (e.g., a blue cell) Allowing it to be trapped inside the slab due to the high index of refraction possible. For another reason, efficient partitioning of the optical spectrum is performed in a manner that allows each solar cell to accommodate a particular subset of the optical spectrum in which it is most efficiently absorbed. The filters used can be omnidirectional filters so that they can cut the appropriate wavelength of light relatively efficiently over a wide angle. With such an omni-directional filter, the angle-average reflection and transmission will be relatively high in the associated band.

The optical module 14 described above may be optionally equipped with an optical condensing module 12 which may comprise one or more condensing devices. In an exemplary system using two condensing devices, a first optical device or a condensing device 16 and a second optical device or condensing device 18 are provided. The illustrated first condensing device 16 is a Fresnel lens while the second condensing device 18 is a complex parabolic condensing device. With respect to the first light focusing device 16, the Fresnel lens can be used as a light source for incident light from a relatively large area lens (e.g., 30 cm wide x 30 cm long) to a relatively narrow area with a lens that is considerably lighter than a conventional lens , But any type of lens or condensing device may be used instead of the Fresnel lens. Thus, a standard lens or a Fresnel lens can efficiently concentrate light from a large area to a narrow area to provide a desired level of light condensation, while a light weight Fresnel lens may provide some structural advantages. The second light converging device or the optical device can use this condensed light outputted from the first light condensing device, if necessary, and further condense it. In this exemplary embodiment, the second condensing device 16 is disposed so that its top surface is spaced from the bottom surface of the Fresnel lens at a distance of about 30 cm, Lt; RTI ID = 0.0 > efficiency. ≪ / RTI > When a condensing device such as a Fresnel lens is used, a large surface area of the lens is exposed to incident light and is concentrated in an area corresponding to the input area of the second condenser lens 18. [

Although the second condensing device 18 is shown as a complex parabolic condensing device in this embodiment, another or additional second / third condensing device may be used instead or additionally. As one example, the second condensing device may be a parabolic condensing device characterized as a flat light panel, which typically provides lower optical efficiency than a complex parabolic condensing device, but can still provide acceptable efficiency. The relative shape and size of the second condensing device 18 shown may include a plurality of different curvilinear shapes for its condenser region other than the shapes shown. The shape and size of the features of the second light concentrator 18 are designed and selected to optimize the concentration of light introduced into the system and provided to the optical module 14. In an alternative aspect of the present invention, the system 10 does not include a plurality of optical concentrating devices operating in series, but instead uses only one or a first optical concentrating device, for example a complex parabolic concentrating device Condensing < / RTI > It should further be understood that additional condensing devices (e.g., a third condensing device) may be used in series with the first and second condensing devices described and illustrated in comparison to these exemplary embodiments.

In the case of a particular optical condensing module 12, the quality and type of condensing device provided is selected to provide the desired desired condensing power in a certain range. For example, the condensing power of the condensing device 12 may include 100 times to 1000 times condensing. However, light levels of less than 100 times or even 1000 times are considered to be within the scope of the present invention. A selected level of condensation can provide a relatively compact condensing module 12 while minimizing the cost of heat loads and components. It should be understood that the illustrated light-collecting module is merely one exemplary light-collecting device or system, wherein many types of light-collecting systems may be additionally or alternatively used as an alternative to or shown in the illustrated and described light-collecting device. The light trapping optical module 14 is disposed below the output end of the condensing module 12 and the output end of the module 12 is disposed in optical communication with the light trapping module 14, It is well illustrated.

5 is a perspective view of a light trapped filtered light concentrator of the present invention that may be incorporated into multiple layers of printed circuit board 90. [ Specifically, the light-capturing optical module 14 includes an interconnecting portion 92 of the upper cell bus bar and an interconnecting portion 93 to the rear contact of the upper cell and an interconnecting portion 94 to the rear or rear contact Are shown together. The rear-mounted heat sink 96 is also shown in an exemplary relationship to the battery stacks 22, 22 'of the module 14.

Fig. 6 is a three-dimensional graph expressing a design space for maximizing light efficiency, in relation to the refractive index of the light trapping dielectric slab and the number of cells. Specifically, the graph shows that a high index of material for the slab and a relatively small number of sub-cells are required to achieve a relatively high optical efficiency. In one example, a system with two sub-cells under a slab (e.g., glass (SiO ₂ )) with a refractive index of 1.5 was calculated to have an optical efficiency of about 69%, while a refractive index of 1.5 Lt; RTI ID = 0.0 > 36% < / RTI > optical efficiency. In another example, a system with two sub-cells under a slab (e.g., GaP) with an index of refraction of about 3.5 was calculated to have an optical efficiency of about 92%.

Figure 7 is a graphical representation of exemplary device efficiency as a function of light collection using the apparatus and concepts of the present invention.

The present invention has been described with reference to several embodiments thereof. The entire disclosure of any patent or patent application identified herein is incorporated herein by reference. The foregoing detailed description and examples have been presented for purposes of clarity and understanding only. No unnecessary limitations from this should be understood. It will be apparent to those skilled in the art that many changes can be made in the embodiments described without departing from the scope of the invention. Accordingly, the scope of the present invention is not limited to the structures described herein, but should be limited only to the structures described by the language of the claims and to the equivalents of such structures.

Claims (15)

A photoregulated dielectric slab having a first side and a second side;
A first cell adjacent to the first side of the dielectric slab and having a bandgap of energy lower than an absorption start energy of the dielectric slab;
At least one filter element in optical contact with a second surface of the dielectric slab; And
A sub-cell array comprising a plurality of photovoltaic sub-cells, wherein at least one of the sub-cells includes a first surface in optical contact with the at least one filter component, - Battery array
And a light trapping optical module including the light trapping optical module. The method according to claim 1,
Wherein a bandgap of the first cell is larger than a bandgap of at least one of the plurality of sub-cells. The method according to claim 1,
Wherein the second side of the dielectric slab comprises a plurality of filter elements, each of the plurality of filter elements being in optical contact with one of the plurality of sub-cells. The method according to claim 1,
And wherein the second side of the dielectric slab comprises the at least one filter component. The method according to claim 1,
Wherein at least one first side of the plurality of sub-cells comprises the at least one filter element. The method according to claim 1,
Wherein the at least one filter component comprises one of a multilayer dielectric stack, a grating, and a photonic crystal. The method according to claim 1,
Wherein the at least one filter component comprises an omnidirectional filter component. The method according to claim 1,
Wherein each of said plurality of sub-cells comprises a multijunction cell. The method according to claim 1,
Wherein the plurality of sub-cells comprises an array of stacked photovoltaic cells. The method according to claim 1,
Wherein the plurality of sub-cells comprises a plurality of first sub-cells having a first band gap and a plurality of second sub-cells having a second band gap,
Wherein the at least one filter component comprises first and second filter components, each corresponding to one of the plurality of first and second sub-cells. The method according to claim 1,
Wherein the first surface of the first cell comprises an antireflective material. The method according to claim 1,
A photovoltaic system, in combination with a printed circuit board. The method according to claim 1,
Wherein the refractive index of the dielectric slab is greater than 2.0 at 550 nm and the index of refraction of the dielectric slab and the first cell provides total internal reflection that captures incident light in the dielectric slab and the first cell. The method according to claim 1,
Further comprising an optical condensing module including an input area into which incident light enters the light collecting module and an output area through which the condensed light exits the light collecting module, wherein the output area is in optical communication with the optical module , Photovoltaic systems. The method according to claim 1,
Wherein each sub-cell of the sub-cell array is electrically insulated and spaced from an adjacent sub-cell by an insulating material.

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