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WO2014136031A1 - Concentrateur optique - Google Patents

Concentrateur optique Download PDF

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Publication number
WO2014136031A1
WO2014136031A1 PCT/IB2014/059382 IB2014059382W WO2014136031A1 WO 2014136031 A1 WO2014136031 A1 WO 2014136031A1 IB 2014059382 W IB2014059382 W IB 2014059382W WO 2014136031 A1 WO2014136031 A1 WO 2014136031A1
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WO
WIPO (PCT)
Prior art keywords
equal
concentrator
width
photovoltaic
less
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2014/059382
Other languages
English (en)
Inventor
Aldo Righetti
Francesco Morichetti
Andrea Annoni
Maria Chiara Ubaldi
Giorgio Grasso
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
FONDAZIONE CENTRO INTERNAZIONALE DELLA FOTONICA PER ENERGIA
Original Assignee
FONDAZIONE CENTRO INTERNAZIONALE DELLA FOTONICA PER ENERGIA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by FONDAZIONE CENTRO INTERNAZIONALE DELLA FOTONICA PER ENERGIA filed Critical FONDAZIONE CENTRO INTERNAZIONALE DELLA FOTONICA PER ENERGIA
Priority to EP14716924.7A priority Critical patent/EP2965365A1/fr
Publication of WO2014136031A1 publication Critical patent/WO2014136031A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F77/00—Constructional details of devices covered by this subclass
    • H10F77/40—Optical elements or arrangements
    • H10F77/42—Optical elements or arrangements directly associated or integrated with photovoltaic cells, e.g. light-reflecting means or light-concentrating means
    • H10F77/484—Refractive light-concentrating means, e.g. lenses
    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47C—CHAIRS; SOFAS; BEDS
    • A47C17/00—Sofas; Couches; Beds
    • A47C17/86—Parts or details specially adapted for beds, sofas or couches not fully covered by any single one of groups A47C17/02 - A47C17/84
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F77/00—Constructional details of devices covered by this subclass
    • H10F77/40—Optical elements or arrangements
    • H10F77/42—Optical elements or arrangements directly associated or integrated with photovoltaic cells, e.g. light-reflecting means or light-concentrating means
    • H10F77/488—Reflecting light-concentrating means, e.g. parabolic mirrors or concentrators using total internal reflection
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/52—PV systems with concentrators

Definitions

  • the present invention is situated in the field of optical concentrators, in particular photovoltaic solar concentrators, more particularly in the field of photovoltaic concentration systems, still more particularly with low concentration.
  • Photovoltaic concentration systems are known in which the solar radiation is concentrated by means of an optical system on the photovoltaic material, in order to substitute part of the high-cost photovoltaic material with an optics that can be made with low-cost technology.
  • the geometric gain (G) of the optical concentration systems defined as the ratio between the area of the inlet opening of the solar radiation and the area occupied by the photovoltaic material on which the radiation is concentrated, can range from values comprised between approximately 1 and 10, for which one refers to low concentration, up to values of 100 and above (high concentration), passing through intermediate values comprised between approximately 10 and 100 (medium concentration).
  • the low concentration systems unlike the medium or high concentration systems, have the advantage of not requiring a sun follower system and allow the collection of a significant fraction of the diffused light.
  • Such low concentration photovoltaic systems have good performances all year round, even when installed in a static manner (i.e. fixed) or quasi-static manner (i.e. with few, preferably only two, adjustments of their orientation during the course of the year).
  • the Applicant has found that the known optical concentrators, including the aforesaid concentrator, do not lack drawbacks and can be improved with regard to various aspects.
  • the Applicant has found that the known optical concentrators are characterized by an unsatisfactory concentration efficiency (see below) and/or by high bulk, in particular the height along the axis of symmetry (see below), and/or by a complex manufacturing and/or installation and/or by a high manufacturing cost.
  • the Applicant has found that the known concentrators comprising a reflective system and a refractive system (including that described above by Edmonds) lead to complications in manufacturing a photovoltaic panel in which a plurality of 2-D concentrators are arranged adjacent and parallel to each other, since they require that each refractive system is separately coupled to the respective reflective system, with consequent increase in terms of production time and costs of the relative panel.
  • the concentrator described by Edmonds requires that each prism is separately situated at the center of the reflective system.
  • an important parameter is the optical concentration efficiency (Pr), defined as the ratio between the optical power that reaches the optical output of the concentrator (and hence the photovoltaic cell) and the total optical power incident on the optical input of the concentrator.
  • Pr optical concentration efficiency
  • the Applicant has found that the known concentrators comprising a reflective system and a refractive system (including that described above by Edmonds), for a given solar concentration factor and a given concentration efficiency (Pr), are characterized by a high value of the aspect ratio (defined as the ratio between the overall height of the concentrator and the width of the optical output).
  • the Applicant has established an industrial standard (or in any case a few industrial standards) is being confirmed with regard to the size and/or weight of the photovoltaic panels without solar concentration and for the relative structural work and installation mode.
  • the Applicant has realized that it is advantageous, in terms of cost and ease of manufacturing, to use the same structural work and the same installation modes of the standard panels also for those static or quasi-static with low concentration.
  • the concentration panels are similar to the standard ones in terms of size (including height) and weight.
  • the Applicant observes that the aforesaid known two- dimensional concentrator described by Edmonds has a plane of symmetry, a main extension along a longitudinal axis belonging to the plane of symmetry and a continuum of sections orthogonal to the longitudinal axis equal to each other along the entire longitudinal extension axis, the section of the plane of symmetry defining an axis of symmetry of the orthogonal section.
  • the radiation incident on the concentrator is characterized by two incidence angles with respect to the axis of symmetry of the section of the concentrator, taken along two planes orthogonal to each other, where the first angle (hereinbelow indicated with 6 N s), is taken along the orthogonal section plane (on which the aforesaid parabolas are defined) and the second angle (indicated with ⁇ ⁇ ⁇ ) on the plane of symmetry of the 2-D concentrator. More precisely, the actual angle of incidence with respect to the axis of symmetry can be projected on the two aforesaid orthogonal planes. In order to facilitate the exposition, in the present application reference will be made to such projections with the expression first and second incidence angle.
  • the Applicant observes that Edmonds considered, for example for the calculation of the concentration efficiency of the aforesaid concentrator, only the first incidence angles 6 N s, assuming the second incidence angle to be equal to zero.
  • the Applicant has found that in reality, it is opportune to consider also the second incidence angle ⁇ , since when the radiation forms a second non-zero angle ⁇ , the Applicant discovered that the behavior of the concentrator (for incident radiation with a first non-zero angle 6 N s) diverges from that with ⁇ ⁇ ⁇ equal to zero, with a deterioration of the concentration efficiency that is greater the higher the aforesaid second incidence angle ⁇ (and the higher the aforesaid first angle 6NS)-
  • the Applicant has realized that in an actual application of a 2-D concentrator, in which the latter is oriented with the longitudinal extension axis (along which the sectional geometry remains constant) parallel to the East-West geographical direction and with the aforesaid orthogonal section parallel to the North-South geographic direction, the solar direction in the course of the day varies its second incidence angle ( ⁇ ⁇ ⁇ ) up to a maximum interval that ranges from -90° up to +90° (with free horizon).
  • the overall efficiency in the course of an entire day of the 2-D concentrator would not be that expected for ⁇ equal to zero, except in the ideal case in which the first incidence angle 6 N s is zero (concentrator oriented in a manner such that the elevation of the axis of symmetry is equal to the elevation of the sun, a condition that can only be verified for at most a few days of the year) .
  • the overall efficiency would typically be less than that expected.
  • the Applicant has found that in a photovoltaic solar concentrator with reflective and refractive system for static or quasi-static installation, it is possible to obtain a low aspect ratio and a high concentration efficiency, and the same time simplify the production process of a relative photovoltaic panel, configuring the refractive system in the shape of a sheet with a suitable ribbing.
  • the invention relates to an optical concentrator, in particular a photovoltaic solar concentrator, having a main extension along a longitudinal axis and a section orthogonal to the longitudinal axis (substantially) equal over a continuum of orthogonal sections taken along at least a portion of the longitudinal extension of the concentrator.
  • optical concentrator also includes, due to the known principle of reciprocity of optical paths, the optical projectors, i.e. the devices in which the optical radiation is projected from an input opening to an output opening having area greater than the input opening.
  • the concentrator comprises a primary reflective system (hereinbelow also indicated as only reflective system) and a secondary refractive system (hereinbelow also indicated as only refractive system) both longitudinally extended and having a respective profile on the orthogonal section.
  • the primary reflective system defines, at two opposite ends thereof, respectively an optical input and an optical output and comprises two mutually facing half-portions having concavities directed towards each other.
  • the refractive system comprises a lower portion supporting an upper portion. The minimum width of the lower portion is greater than the maximum width of the upper portion.
  • the optical output lies on a lower side of the lower portion, the minimum width of the lower portion being greater than or equal to the width of the optical output.
  • the sectional profile of the upper portion has an aspect ratio (ratio between the height and the maximum width) less than or equal to 0.43, preferably less than or equal to 0.3.
  • the sectional profile of each half-portion of the reflective system is extended from a respective initial point on an upper side of the lower portion and laterally adjacent to or in proximity to the upper portion up to an end point on the optical input, and comprises preferably a segment substantially shaped according to a parabola.
  • the terms 'height', 'vertical', 'lower', 'upper' and 'surmounted' are defined in relation to a direction lying on the orthogonal section and generically directed according to a low-high sense that extends from the optical output to the optical input.
  • the surfaces (or in section, the sides) which delimit the portions of the refractive systems can correspond to actual surfaces of separation between different materials (such as the dielectric material / air separation surface) or they can correspond to ideal surfaces being extended inside a continuous dielectric material (as will be clear in the following description, for example from that shown in figure 2 or 7).
  • the aforesaid geometric form of the refractive system having a lower portion surmounted by an upper portion, with the lower portion wider than the upper portion and also wider than the optical output, and the upper portion with an aspect ratio less than or equal to 0.43, and the fact that the sectional profile of each half-portion of the reflective system is extended from a respective initial point on an upper side of the lower portion and laterally adjacent to or in proximity to the upper portion, allow giving structural continuity to the refractive systems of a plurality of concentrators side-by-side in a photovoltaic panel, while collecting sufficient light radiation at the optical output (and hence on the photovoltaic cell).
  • a comparative refractive system composed of a prism with triangular section, of known type, above a lower portion such as that of the present invention, due to the excess divergence of the optical beam at the base of the triangle, would determine an unsatisfactory collection of radiation on the optical output, after the propagation through the lower portion.
  • the Applicant has also discovered that the aforesaid structure of the concentrator allows obtaining a low aspect ratio of the concentrator and at the same time a high concentration efficiency, at least at values of the geometric gain comprised between about 3 and 5, for a static or quasi- static installation.
  • the concentrator has a plane of symmetry comprising the longitudinal axis, and an axis of symmetry defined by said plane of symmetry on the orthogonal section.
  • the upper and lower portions of the refractive system are centered on the axis of symmetry.
  • the two half-portions of the reflective system are arranged mirrored with respect to the plane of symmetry.
  • the sectional profile of the lower portion of the refractive system is rectangular-shaped, the optical output lying on the lower longer side of the rectangle and the lower side of the upper portion of the refractive system lying on the upper longer side of the rectangle.
  • the sectional profile of the upper portion of the refractive system is convex-shaped with upwardly directed convexity, more preferably it is trapezoid-shaped (typically isosceles trapezoid).
  • each half-portion of the reflective system is extended from a point on, or in proximity to, the respective vertex at the base of the trapezoid.
  • the internal angle at the base of the trapezoid is greater than or equal to 30°, preferably greater than or equal to 35°, and/or less than or equal to 50°, preferably less than or equal to 45°.
  • the width (w) of the optical output (coinciding with the width of the photovoltaic cell) is greater than or equal to 3mm, preferably greater than or equal to 5mm, and/or less than or equal to 20mm, preferably less than or equal to 15mm, for example 10mm.
  • the width of the (upper) shorter base of the trapezoid is greater than or equal to 0.3w, preferably greater than or equal to 0.4w, and/or less than or equal to 0.7w, preferably less than or equal to 0.6w, for example 0.5w.
  • the height of the trapezoid is greater than or equal to 0.2w, preferably greater than or equal to 0.25w, and/or less than or equal to 0.4w, preferably less than or equal to 0.35w, for example 0.31 w.
  • the height of the rectangle is greater than or equal to 0.2w, preferably greater than or equal to 0.25w, and/or less than or equal to 0.4w, preferably less than or equal to 0.35w, for example 0.3w.
  • the height of the rectangle is greater than or equal to about 2mm, preferably greater than or equal to 2.5mm, and/or less than or equal to 4 mm, preferably less than or equal to 3.5mm, for example 3mm.
  • the base sheet of the photovoltaic panel without giving it excessive weight.
  • the width of the longer sides of the rectangle is greater than or equal to 2w, preferably greater than or equal to 3w, and/or less than or equal to 6w, preferably less than or equal to 5w, for example 4w (such width typically being equal to Gw).
  • each refractive system of the present invention can be each refractive system having as sectional profile not the aforesaid trapezoid and/or rectangle, but rather any form (for example for the trapezoid a cylindrical lens with upward convexity) in which each point of its edge lies less than 10% of the width of the optical output (w) away from the corresponding point of the trapezoid and/or, rectangle, respectively.
  • the sectional profile of each half-portion of the reflective system is substantially shaped according to a parabola.
  • Such point of connection lies on an upper side of the sectional profile of the lower portion (typically in the aforesaid base vertex of the trapezoid).
  • the aspect ratio of the concentrator is greater than or equal to 3 and/or less than or equal to 5.
  • the overall height of the concentrator is less than or equal to 200mm, preferably less than or equal to 100 mm.
  • the ratio G (geometric gain) between the area of the optical input (or the sectional width thereof) and the area of the optical output (or the sectional width thereof) is greater than 2, preferably greater than or equal to 3, and/or less than or equal to 6, preferably less than or equal to 5.
  • the concentrator comprises a convergent lens arranged above the optical input and having width substantially equal to the width of the optical input.
  • the lens advantageously contributes to further reducing the aspect ratio.
  • the lens comprises a cylindrical lens with axis along the longitudinal axis and width substantially equal to the width of the optical input and having radius on the orthogonal section greater than or equal to 6w, preferably greater than or equal to 7w, and/or less than or equal to 10w, preferably less than or equal to 9w, for example 8w.
  • the lens further comprises a portion arranged with continuity above the cylindrical lens and having on the orthogonal section a horizontal rectangle shape with width substantially equal to the width of the optical input.
  • the rectangular portion confers structural strength to the lens and advantageously allows, in a multi-concentrator photovoltaic panel, integrating the plurality of lenses in a single continuous sheet.
  • each half-portion of the reflective system at the end point on the optical input is substantially rounded along an arc of a circle having radius d less than or equal to 2mm.
  • the synergistic effect of the lens and of the rounding allows an optimization of the concentration efficiency, since it reduces the radiation loss on the end point of the reflective system.
  • the distance along the vertical direction between the end point of the reflective system and the lens is greater than zero, more preferably it depends on the aforesaid curvature radius, said distance being such that the tangent to the aforesaid arc of a circle at the point of connection coincides with the tangent to the parabola at the same point of connection.
  • the secondary refractive system and/or the lens is/are made of glass with silica base, such as silica oxide or borosilicates preferably with low iron content, or made of polymer material such as PolyMethylMethAcrylate (PMMA), Polycarbonate, Cyclo-Polyolefin, etc.
  • the refractive system and/or the lens is/are made by means of roller molding or injection molding or by casting or via extrusion.
  • the refractive system and/or the lens is/are externally covered with an anti- reflection layer (in order to reduce the radiation reflected at the dielectric material / air interface to below 1 %).
  • the refraction index (n 2 ) of the refractive system is greater than or equal to 1 .3, more preferably greater than or equal to about 1 .5.
  • the refraction index (n 2 ) of the refractive system is less than or equal to 2.5.
  • the primary reflective system defines an internal space within which the upper portion of the secondary refractive system (and not the lower portion) is situated and more preferably the portion of the internal space left free of the secondary refractive system is filled with air.
  • the aforesaid portion of the internal space left free of the upper portion of the secondary refractive system is filled with a dielectric material having refraction index (n-i) less than that of the refractive system.
  • the actual concentration factor on the section plane (first angle 6 N s) is increased and/or the concentration efficiency (following the 'recovery' of the second incidence angle ⁇ on the plane of symmetry) is increased.
  • the refraction index (n-i) of the dielectric material in the aforesaid portion of the internal space is less than or equal to 1 .6.
  • the orthogonal section is (substantially) equal over a continuum of sections taken along substantially the entire longitudinal extension (except possibly for the two longitudinal ends) of the concentrator.
  • the refractive system comprises a non-linear optical material (or fluorescent) adapted to achieve an optical wavelength conversion (thus increasing the energy conversion efficiency of the solar light).
  • the refractive system comprises polymer materials doped with florescent materials such as organic molecules or nano-particles capable of absorbing two low-energy infrared photons, emitting one of these with high energy (or generally greater) absorbable by the photovoltaic cell (up- conversion) and/or absorb a high-energy photon, emitting two of these with intermediate energy absorbable by the photovoltaic cell (down- conversion).
  • the primary reflective system is made of plastic (polymer) material covered with a thin (film) layer made of reflective material such as aluminum, silver or alloys thereof.
  • the reflective system is obtained via molding of plastic material laminates.
  • the primary reflective system is a metal plate suitably shaped and covered with a film made of reflective material. The reflectivity of the reflective surfaces is preferably greater than 85%, preferably greater than 90%.
  • the invention in a second aspect, relates to a photovoltaic system comprising the optical concentrator in accordance with the first aspect (in the various embodiments) of the present invention and a photovoltaic cell optically coupled to the optical output, preferably arranged at the optical output (e.g. the width of the optical output coincides with the width of the photovoltaic cell), more preferably fixed (for example with acrylic glue with ultraviolet cross-linking) to a lower surface of the lower portion of the refractive system (e.g. of the rectangle).
  • a photovoltaic system comprising the optical concentrator in accordance with the first aspect (in the various embodiments) of the present invention and a photovoltaic cell optically coupled to the optical output, preferably arranged at the optical output (e.g. the width of the optical output coincides with the width of the photovoltaic cell), more preferably fixed (for example with acrylic glue with ultraviolet cross-linking) to a lower surface of the lower portion of the refractive system (e.g. of the rectangle).
  • the photovoltaic cell is made of silicon (e.g. mono- or poly- crystalline), preferably with the ohmic contacts all on the same side ("back contacted"), and/or where the silicon is surface treated in a manner so as to cancel the reflected light and enlarge the absorption spectrum ("black silicon”).
  • the photovoltaic cell is made of gallium and indium nitride, and/or of the type with double or triple junction, and/or with semi- transparent thin films such as CdTe or CIGS, etc.
  • the photovoltaic system can comprise a thermal dissipater associated with the photovoltaic cell on the side opposite the refractive system, in order to limit the operating temperature of the cell itself, and consequently to maintain its conversion efficiency at high levels.
  • the invention in a third aspect, relates to a photovoltaic panel comprising a plurality of photovoltaic systems according to the second aspect (in the various embodiments) of the present invention, arranged side-by-side and with the longitudinal extension axis parallel to each other, in a manner such that each photovoltaic system is in contact with the adjacent system (s).
  • each (e.g. the first and the second) half-portion of each reflective system (excluding those at the transverse ends of the panel) has the end edge at the optical input proximal and in structural continuity (or coinciding) with the end edge at the optical input of a corresponding (i.e. the second and the first, respectively) adjacent half-portion of an adjacent reflective system.
  • the panel comprises a plurality of metal plates (for example made of aluminum or an alloy thereof), preferably covered as described above, each suitably bent in order to obtain, in a single body, the two aforesaid continuous half-portions of two adjacent different reflective systems.
  • the panel comprises, on its lower part, a first sheet made in a single piece and made of dielectric material (for example as described above), suitably shaped in order to obtain in a single body the aforesaid plurality of refractive systems parallel to each other, wherein the plurality of photovoltaic cells is mechanically fixed to a lower surface of said sheet.
  • a first sheet made in a single piece and made of dielectric material (for example as described above), suitably shaped in order to obtain in a single body the aforesaid plurality of refractive systems parallel to each other, wherein the plurality of photovoltaic cells is mechanically fixed to a lower surface of said sheet.
  • a sheet made of EVA ethylvinylacetate
  • the panel comprises on its upper part a second sheet made in a single piece and made of dielectric material (for example as described above), suitably shaped in order to obtain, in a single body, the aforesaid plurality of lenses parallel to each other.
  • one such structure is capable of reducing the manufacturing costs and/or installation costs of the panel.
  • the invention relates to a method for producing a photovoltaic panel according to the third aspect of the invention, comprising:
  • the plurality of photovoltaic cells (each possibly comprising a printed electrical connection board, Printed Circuit Board or PCB) to the lower surface of the first sheet;
  • a perimeter frame for example made of metal
  • the invention relates to a method for installing and/or operating a photovoltaic panel according to the fourth aspect of the present invention, wherein the panel is oriented in a manner such that the longitudinal axis is arranged along the EAST-WEST geographic direction.
  • the aforesaid method of installation and/or operation comprises orienting the panel (preferably only during the installation, without further subsequent orientation interventions), in a manner such that the axis of symmetry has an elevation (angle formed with the horizon) substantially equal to that of the sun during equinox days.
  • the aforesaid method for installing and/or operating comprises orienting the panel two times (preferably, but not exclusively, only two times) during a solar year, wherein the first time the axis of symmetry of the concentrator assumes an elevation (angle formed with the horizon) comprised between (preferably equal to the intermediate value between) the elevation of the sun during equinox days and the elevation of the sun on the day of the summer solstice, and wherein the second time the axis of symmetry assumes an elevation comprised between (preferably equal to the intermediate value between) the elevation of the sun during equinox days and the elevation of the sun on the day of the winter solstice.
  • the first orientation is executed on a day that falls within a month of the spring equinox and the second orientation is executed on a day that falls within a month of the autumn equinox.
  • FIG. 1 shows a schematic perspective view of a possible embodiment of an optical concentrator in accordance with the present invention, with several parts transparent;
  • FIG. 2 shows a schematic orthogonal section of a photovoltaic system containing the concentrator in accordance with the present invention
  • FIG. 3a and 3b show a schematic and partial orthogonal section of an optical concentrator in accordance with the present invention, in which the paths of the rays of the light radiation are shown, numerically calculated for a value of the first 6NS respectively equal to 0° and 1 2.5° and of the second incidence angle ⁇ equal to 0°;
  • FIG. 4a and 4b show a schematic and partial orthogonal section of an optical concentrator in accordance with the present invention, in which the paths of the rays of the light radiation are shown, numerically calculated for a value of the first 6NS respectively equal to 0° and 1 2.5° and of the second incidence angle ⁇ ⁇ ⁇ equal to 58°;
  • FIG. 5 schematically shows the sectional profile of the half-portion of the reflective system in accordance with the present invention
  • FIG. 6 shows the results of a numeric calculation of the concentration efficiency of an optical concentrator in accordance with the present invention for different first and second incidence angles
  • FIG. 7 shows a schematic and partial orthogonal section of a photovoltaic panel in accordance with the present invention.
  • a concentrator according to the present invention is indicated in its entirety with the reference number 1
  • a photovoltaic system according to the present invention is indicated in its entirety with the reference number 10
  • a photovoltaic panel according to the present invention is indicated in its entirety with the reference number 100.
  • the concentrator 1 typically has a plane of symmetry 2, a main extension along a longitudinal axis 3 belonging to the plane of symmetry and a section taken along a plane 4 (shown in fig. 1 by way of example) orthogonal to the longitudinal axis.
  • the section of the plane of symmetry 2 defines an axis of symmetry 5 of the orthogonal section.
  • section it is intended the result of the intersection of an element, e.g. the concentrator, with a plane, in terms of two-dimensional profiles or shapes of the components of the element.
  • the radiation incident on the concentrator has an actual incidence angle with respect to the axis of symmetry that can be conventionally projected on two planes that are orthogonal to each other, in a manner so as to define a first and a second incidence angle with respect to the axis of symmetry, wherein the first incidence angle (6NS) is taken along the section plane 4 and the second incidence angle ( ⁇ ⁇ ⁇ ) is taken along the plane of symmetry 2.
  • the orthogonal section of the concentrator is (substantially) equal over a continuum of orthogonal sections taken along at least a portion of the longitudinal extension of the concentrator (preferably a substantial portion, for example a longitudinally central portion that is extended over at least 75% or 90% of the overall longitudinal extension of the concentrator).
  • the concentrator comprises a primary reflective system 6 and a secondary refractive system 7 both longitudinally extended and having a respective profile on the orthogonal section (for example shown in fig. 2).
  • the primary reflective system 6 defines, at two opposite ends thereof along the axis of symmetry 5, respectively an optical input 8 and an optical output 9 both arranged orthogonal to the axis of symmetry 5.
  • the primary reflective system 6 defines an internal space 14, where for example the portion of the internal space left free of the refractive system 7 is filled with air.
  • the reflective system 6 comprises two half-portions arranged mirrored with respect to the plane of symmetry 2 and having concavity directed towards the axis of symmetry.
  • the refractive system comprises a lower portion 1 1 , typically having sectional profile with rectangle shape and an upper portion 12, typically having sectional profile with trapezoid shape, both centered on the axis of symmetry 5, the longer sides of the rectangle being orthogonal to the axis of symmetry, the longer base 13 of the trapezoid lying on the upper longer side 14 of the rectangle (in other words, the rectangle and trapezoid are continuous) and the optical output 9 lying on the lower longer side 15 of the rectangle.
  • the longer side 14, 15 of the rectangle is longer than both the longer base 13 of the trapezoid and the optical output 9 and typically equal to the width of the optical input 8.
  • each half-portion of the reflective system is extended from an initial point 16 on, or in proximity (see fig. 5) to the respective vertex at the base of the trapezoid up to an end point 17 on the optical input, and comprises preferably a segment 18 substantially shaped according to a parabola.
  • each half-portion of the reflective system at the end point 17 on the optical input is substantially rounded along an arc of a circle.
  • the concentrator comprises a convergent lens 20 arranged above the optical input and having width substantially equal to the width of the optical input.
  • the convergent lens 20 comprises a cylindrical lens 21 with axis along the longitudinal axis and width substantially equal to the width of the optical input and also a rectangular portion 22 arranged with continuity above the cylindrical lens and with width substantially equal to the width of the optical input.
  • the orthogonal section is (substantially) equal over a continuum of sections taken along substantially the entire longitudinal extension (except for the two longitudinal ends) of the concentrator 1 .
  • each of the two longitudinal ends of the concentrator 1 is closed by a respective flat wall (not shown in figure 1 ), preferably having reflective surface directed towards the internal space 14 (or alternatively a transparent wall).
  • the photovoltaic system 10 comprises the solar concentrator 1 and a photovoltaic cell 30 optically coupled to the optical output 9.
  • the photovoltaic cell 30 is preferably arranged at the optical output 9, more preferably fixed (for example with acrylic glue with ultraviolet cross-linking) to a lower surface of the rectangle, possibly by means of interposition of a PCB which is directly fixed (for example with cyanoacrylic glue) to the lower surface.
  • the photovoltaic system 10 comprises a pair of metal plates 40 (for example made of aluminum or an alloy thereof), preferably covered with a film made of reflective material, suitably bent in order to obtain the primary reflective system 6.
  • a pair of metal plates 40 for example made of aluminum or an alloy thereof
  • a film made of reflective material suitably bent in order to obtain the primary reflective system 6.
  • FIG. 3a, 3b, 4a, 4b and 6 show the results of numeric simulations conducted with a processing program with tracing of the solar rays on a mathematical optical concentrator model in accordance with the present invention and having sectional profile as in figure 2.
  • the first incidence angle is equal to 0° for the figures 3a and 4a, and is equal to 12.5° for the figures 3b and 4b
  • the second incidence angle is equal to 0° for the figures 3a and 3b and is equal to 58° for the figures 4a and 4b.
  • the figures intuitively show how the concentrator in accordance with the present invention has a good performance in terms of capacity of concentration of the radiation on the optical output also at the extreme values of the incidence angles for quasi-static installations.
  • the Applicant established that the concentrators having reflective system lying in said portion of space allow obtaining the desired performances in terms of aspect ratio (from approximately 3 to approximately 4), geometric gain (from approximately 3 to approximately 5) and concentration efficiency.
  • Figure 6 shows the simulated concentration efficiency Pr (vertical axis) of the exemplifying concentrator described above for different (degree) values of the second incidence angle (horizontal axis) and for different values of the first incidence angle (according to the figure legend).
  • the Applicant has also conducted a comparison simulation between the concentrator of the present invention described above and a mathematical model of a comparative optical concentrator, of the type described in the abovementioned patent document AU-A-70929/87.
  • Pr eq is the concentration efficiency Pr integrated on second angles ⁇ that vary in the interval ⁇ 58° and on first angles 6NS which vary in the interval ⁇ 1 2.5°, wherein in the integration the actual (astronomic) variation is accounted for of the first and second angle over an entire solar year.
  • concentration efficiency is deemed to be a good indicator of the actual performance of the concentrator (and of the relative panel) in the course of a full year, when installed in a quasi-static mode (i.e. with only two adjustments per year) with the longitudinal axis parallel to the EAST-WEST direction.
  • the concentrator of the present model allows obtaining, in quasi-static mode, a higher concentration efficiency with respect to the aforesaid known concentrator.
  • Figure 7 shows the schematic and partial orthogonal section of an exemplifying photovoltaic panel 1 00 comprising a plurality (in the figure, only three are shown) of photovoltaic systems 1 0 as exemplifyingly described above, arranged side-by-side and with the longitudinal extension axes parallel to each other, in a manner such that each photovoltaic system is in contact with the adjacent system(s).
  • the panel comprises a plurality of metal plates 40 (for example made of aluminum or an alloy thereof), each suitably bent in order to obtain, in a single body, the two aforesaid continuous half-portions of two adjacent different reflective systems.
  • metal plates 40 for example made of aluminum or an alloy thereof
  • the panel comprises on its lower part a first sheet 41 made in a single piece and made of dielectric material, suitably shaped in order to obtain, in a single body, the aforesaid plurality of refractive systems parallel to each other, wherein the plurality of photovoltaic cells is mechanically fixed to a lower surface of the sheet.
  • the panel comprises, on its upper part, a second sheet 42 made in a single piece and made of dielectric material, suitably shaped in order to obtain, in a single body, the aforesaid plurality of lenses parallel to each other.
  • the panel 100 described above with reference to figure 7 can be produced according to the following operations:
  • the plurality of photovoltaic cells (each possibly comprising a printed electrical connection board, Printed Circuit Board or PCB) to the lower surface of the first sheet;
  • a perimeter frame for example made of metal, not shown

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  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Nursing (AREA)
  • Photovoltaic Devices (AREA)
  • Glass Compositions (AREA)
  • Optical Couplings Of Light Guides (AREA)

Abstract

Cette invention concerne un système (10) et un panneau photovoltaïque (100), comprenant une cellule photovoltaïque et un concentrateur solaire photovoltaïque (1) comprenant un système réfléchissant (6) et un système de réfraction (7), le système réfléchissant comprenant deux demi parties orientées face à face et présentant des concavités se fraisant face, et le système de réfraction comprenant une partie inférieure supportant une partie supérieure, la largeur la plus petite de la partie inférieure étant supérieure à la largeur la plus grande de la partie supérieure. Ladite cellule photovoltaïque (30) repose sur le côté inférieur de la partie inférieure (15) du système de réfraction. Le profil de section de la partie supérieure présente un rapport longueur/largeur inférieur ou égal à 0,43.
PCT/IB2014/059382 2013-03-04 2014-03-03 Concentrateur optique Ceased WO2014136031A1 (fr)

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IT000317A ITMI20130317A1 (it) 2013-03-04 2013-03-04 Concentratore ottico
US201361833097P 2013-06-10 2013-06-10
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US20210111668A1 (en) * 2019-10-10 2021-04-15 SunDensity Inc. Method and apparatus for increased solar energy conversion

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AU7092987A (en) 1986-04-03 1987-10-08 Ian Robert Edmonds Solar energy collector with a prism
WO2004114419A1 (fr) * 2003-06-20 2004-12-29 Schripsema Jason E Module photovoltaique compose lineaire et reflecteur associe
EP1852919A2 (fr) * 2006-05-05 2007-11-07 SolFocus, Inc. Dispositif photovoltaïque concentré solaire, refroidi passivement
US20090146049A1 (en) * 2004-09-24 2009-06-11 Epistar Corporation Optoelectronic device assembly
EP2169728A2 (fr) * 2008-09-26 2010-03-31 Industrial Technology Research Institute Procédé et système pour la concentration de lumière et appareil de conversion d'énergie lumineuse
US20100139768A1 (en) * 2008-12-10 2010-06-10 Solfocus, Inc. Heat spreading shield
US20100269886A1 (en) * 2009-04-27 2010-10-28 Sun Edge LLC Non-imaging light concentrator

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Publication number Priority date Publication date Assignee Title
AU7092987A (en) 1986-04-03 1987-10-08 Ian Robert Edmonds Solar energy collector with a prism
WO2004114419A1 (fr) * 2003-06-20 2004-12-29 Schripsema Jason E Module photovoltaique compose lineaire et reflecteur associe
US20090146049A1 (en) * 2004-09-24 2009-06-11 Epistar Corporation Optoelectronic device assembly
EP1852919A2 (fr) * 2006-05-05 2007-11-07 SolFocus, Inc. Dispositif photovoltaïque concentré solaire, refroidi passivement
EP2169728A2 (fr) * 2008-09-26 2010-03-31 Industrial Technology Research Institute Procédé et système pour la concentration de lumière et appareil de conversion d'énergie lumineuse
US20100139768A1 (en) * 2008-12-10 2010-06-10 Solfocus, Inc. Heat spreading shield
US20100269886A1 (en) * 2009-04-27 2010-10-28 Sun Edge LLC Non-imaging light concentrator

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20210111668A1 (en) * 2019-10-10 2021-04-15 SunDensity Inc. Method and apparatus for increased solar energy conversion
US11750150B2 (en) * 2019-10-10 2023-09-05 SunDensity Inc. Method and apparatus for increased solar energy conversion

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