U.S. patent application number 12/841823 was filed with the patent office on 2010-11-25 for thermal spray for solar concentrator fabrication.
This patent application is currently assigned to Palo Alto Research Center Incorporated. Invention is credited to Hing Wah Chan, David G. Duff, John S. Fitch, Michael C. Weisberg.
Application Number | 20100294364 12/841823 |
Document ID | / |
Family ID | 39675132 |
Filed Date | 2010-11-25 |
United States Patent
Application |
20100294364 |
Kind Code |
A1 |
Chan; Hing Wah ; et
al. |
November 25, 2010 |
Thermal Spray For Solar Concentrator Fabrication
Abstract
A solar concentrator including a substantially-transparent
optical element, a reflective material disposed on a convex surface
of the optical element, an insulator layer on the reflective
material, a conductive material that is thermal sprayed onto the
insulator layer, and a solar cell mounted in a central region of
the convex surface and electrically coupled to the conductive
material. The optical element includes a flat surface disposed
opposite to the convex surface and a concave surface defined in the
flat surface. The convex surface and concave surface are arranged
and the reflective material is deposited such that light passing
through the flat surface is reflected by the reflective material
toward the concave surface, and is re-reflected by the reflective
material disposed on the concave surface onto an active surface of
the solar cell. Thermal spraying the conductive material may
include spraying a molten metal powder onto the insulator
layer.
Inventors: |
Chan; Hing Wah; (San Jose,
CA) ; Fitch; John S.; (Los Altos, CA) ;
Weisberg; Michael C.; (Woodside, CA) ; Duff; David
G.; (Portola Valley, CA) |
Correspondence
Address: |
BEVER, HOFFMAN & HARMS, LLP
901 CAMPISI WAY, SUITE 370
CAMPBELL
CA
95008
US
|
Assignee: |
Palo Alto Research Center
Incorporated
Palo Alto
CA
|
Family ID: |
39675132 |
Appl. No.: |
12/841823 |
Filed: |
July 22, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11782605 |
Jul 24, 2007 |
|
|
|
12841823 |
|
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|
|
60899150 |
Feb 2, 2007 |
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Current U.S.
Class: |
136/259 ; 156/60;
204/192.25; 257/E31.127; 438/65 |
Current CPC
Class: |
H01L 2224/16237
20130101; H01L 31/054 20141201; Y10T 156/10 20150115; H01L
2224/05568 20130101; H01L 2224/0556 20130101; H01L 2224/05599
20130101; H01L 2924/00014 20130101; H01L 2224/0555 20130101; H01L
2924/014 20130101; H01L 2224/13101 20130101; H01L 2224/0554
20130101; H01L 2924/00014 20130101; H01L 2924/00014 20130101; H01L
2224/05573 20130101; H01L 2224/13101 20130101; H01L 2924/00014
20130101; H01L 24/16 20130101; Y02E 10/52 20130101; H01L 24/13
20130101; H01L 2924/00014 20130101; H01L 31/0547 20141201 |
Class at
Publication: |
136/259 ;
204/192.25; 156/60; 438/65; 257/E31.127 |
International
Class: |
H01L 31/0232 20060101
H01L031/0232; C23C 14/34 20060101 C23C014/34; B32B 37/00 20060101
B32B037/00 |
Claims
1. A method for producing a solar concentrator, the method
comprising: depositing a reflective material on a convex surface
substantially-transparent optical element, the optical element
including a flat surface disposed opposite to the convex surface,
wherein the reflective material is deposited such that light
passing through the flat surface is reflected by the reflective
material disposed on the convex surface; depositing an insulative
material on the reflective material; and thermal spraying a
conductive material onto the insulative material.
2. The method of claim 1, wherein the optical element further
includes a concave surface defined in the flat surface, the convex
surface and concave surface being arranged such that said light
reflected by the reflective material disposed on the convex surface
is directed toward the concave surface, and wherein the method
further comprises: depositing said reflective material on the
concave surface of the optical element; and mounting a solar cell
onto a central region of the convex surface of the optical element
such that the solar cell is electrically coupled to the conductive
material, wherein the reflective material is deposited on the
concave surface such that said light reflected from the reflective
material disposed on the convex surface is re-reflected by the
reflective material disposed on the concave surface toward the
solar cell.
3. The method according to claim 2, wherein thermal spraying the
conductive material comprises thermal spraying a molten metal
powder onto the insulative material.
4. The method according to claim 3, wherein thermal spraying the
conductive material comprises thermal spraying one or more of gold,
nickel and copper.
5. The method according to claim 3, wherein spraying the molten
metal powder onto the optical element comprises: placing a stencil
on the optical element; and spraying a molten metal powder onto the
stencil and the insulative material layer.
6. The method according to claim 5, further comprising removing the
stencil to expose an aperture from which light may pass out of the
optical element, wherein mounting the solar cell comprises
positioning the solar cell in the central region of the convex
surface such that an optically-active area of the solar cell is
aligned with the aperture.
7. The method according to claim 5, wherein the stencil comprises a
mechanical, hard or soft tooling.
8. The method according to claim 1, wherein depositing the
reflective material comprises depositing a mirror coating using one
of sputtering, physical vapor deposition and liquid deposition.
9. The method according to claim 1, wherein depositing the
insulative material comprises depositing a powder-coated
polymer.
10. The method according to claim 1, wherein depositing the
insulative material comprises a polymer using one of spraying,
dipping and lamination.
11. A solar concentrator comprising: a substantially-transparent
optical element including a flat surface and a convex surface
disposed opposite to the flat surface; a first reflective material
layer disposed on the convex surface of the optical element,
wherein the first reflective material layer is deposited such that
light passing through the flat surface is reflected by the first
reflective material layer into the optical element; an insulative
material layer disposed on the first reflective material layer; and
a thermal-sprayed conductive material layer disposed on the
insulative material layer.
12. The solar concentrator of claim 11, wherein the optical element
further includes a concave surface defined in the flat surface, the
convex surface and concave surface being arranged such that said
light reflected by the first reflective material layer is directed
toward the concave surface, wherein the solar concentrator further
comprises: a second reflective material layer disposed on the
concave surface of the optical element; and a solar cell mounted
onto the optical element and disposed a central region of the
convex surface of the optical element such that the solar cell is
electrically coupled to the conductive material layer, wherein the
reflective material is deposited on the concave surface such that
said light reflected from the reflective material disposed on the
convex surface is re-reflected by the reflective material disposed
on the concave surface toward the solar cell.
13. The solar concentrator of claim 12, wherein the conductive
material layer comprises a molten metal powder.
14. The solar concentrator according to claim 13, wherein the
molten metal powder comprises one or more of gold, nickel and
copper.
15. The solar concentrator according to claim 14, wherein the
optical element includes an aperture disposed in a central region
of the convex surface from which light may pass out of the optical
element, wherein the solar cell is positioned in the central region
of the convex surface such that an optically-active area of the
solar cell is aligned with the aperture.
16. The solar concentrator according to claim 11, wherein the
reflective material layer comprises a mirror coating.
17. The solar concentrator according to claim 11, wherein the
insulative material layer comprises a powder-coated polymer.
18. The solar concentrator according to claim 11, wherein the
insulative material layer comprises a polymer.
19. A solar concentrator comprising: a substantially-transparent
optical element including a flat surface, a convex surface disposed
opposite to the flat surface, and a concave surface defined in the
flat surface; a first reflective material layer disposed on the
convex surface of the optical element; a second reflective material
layer disposed on the cave surface of the optical element; an
insulative material layer disposed on the first reflective material
layer; a thermal-sprayed conductive material layer disposed on the
insulative material layer; and a solar cell mounted onto the
optical element and disposed a central region of the convex surface
of the optical element such that the solar cell is electrically
coupled to the conductive material layer, wherein the first and
second reflective material layers are deposited and arranged by the
convex and concave surfaces such that light passing through the
flat surface is reflected by the first reflective material layer
toward the second reflective material layer, and is re-reflected by
the second reflective material layer onto the solar cell.
20. The solar concentrator according to claim 11, wherein the first
and second reflective material layers comprises a mirror coating,
wherein the insulative material layer comprises a polymer, wherein
thermal-sprayed conductive material layer comprises a molten metal
powder including one or more of gold, nickel and copper.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional of U.S. patent
application Ser. No. 11/782,605, filed on Jul. 24, 2007 and
entitled "Thermal Spray For Solar Concentrator Fabrication" and
claims priority to U.S. Provisional Patent Application Ser. No.
60/899,150, filed on Feb. 2, 2007 and entitled "Concentrated
Photovoltaic Energy Designs", the contents of which are
incorporated herein by reference for all purposes.
BACKGROUND
[0002] 1. Field
[0003] Some embodiments generally relate to the collection and
concentration of solar radiation. More specifically, embodiments
may relate to systems to efficiently fabricate solar radiation
collectors.
[0004] 2. Brief Description
[0005] A concentrating solar radiation collector may convert
received solar radiation (i.e., sunlight) into a concentrated beam
and direct the concentrated beam onto a small photovoltaic cell.
The cell, in turn, converts the photons of the received beam into
electrical current.
[0006] U.S. Patent Application Publication No. 2006/0231133
describes several types of concentrating solar collectors. As
described therein, a concentrating solar collector may include
reflective material for directing received solar radiation,
conductive material to carry electrical current generated from the
solar radiation, and/or insulative material to isolate various
conductors from one another. Fabrication of a solar radiation
collector using one or more of these materials may be unsuitably
complex and costly.
[0007] For example, conventional techniques for depositing these
materials may include evaporating or sputtering within an
established vacuum. Thin film lithographic techniques are employed
to create desired patterns and features in the deposited materials.
Such techniques require photoresist deposition, masking, UV
exposure, and subsequent etching for each layer of material. Thin
film lithography may provide geometrically accuracy but entails
significant expense.
SUMMARY
[0008] To address at least the foregoing, some aspects provide a
method, means and/or process steps for providing a solar
concentrator including a reflective material deposited over a
convex surface of a substantially-transparent optical element
(core), an insulator layer deposited over the reflective material,
a conductive (first) material that is thermal-sprayed onto the
insulator, and a solar cell mounted on the optical element and
electrically coupled to the conductive material. The optical
element includes a flat surface disposed opposite to the convex
surface, and a concave surface formed in the flat surface, wherein
the convex surface and concave surface are arranged and the
reflective material is deposited such that light passing through
the flat surface is reflected by the reflective material toward the
concave surface.
[0009] In some aspects, thermal spraying the conductive material
may include spraying a molten metal powder onto the insulator
layer. Moreover, spraying the molten metal powder may include
placing a stencil over the optical element and spraying a molten
metal powder onto the stencil and the insulator layer.
[0010] In other aspects, the optical element also includes an
aperture defined in a central region of the convex surface from
which light reflected from reflective material disposed on the
concave surface may pass out of the optical element to the solar
cell. An electrical contact of the solar cell is coupled to the
hardened metal powder, and an optically-active area of the solar
cell is aligned with the aperture.
[0011] In yet other aspects, the insulator may include a
powder-coated polymer.
[0012] The claims are not limited to the disclosed embodiments,
however, as those in the art can readily adapt the description
herein to create other embodiments and applications.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The construction and usage of embodiments will become
readily apparent from consideration of the following specification
as illustrated in the accompanying drawings, in which like
reference numerals designate like parts
[0014] FIG. 1 is a flow diagram of a method according to some
embodiments.
[0015] FIG. 2A is a perspective view of a portion of an optical
element and conductive material according to some embodiments.
[0016] FIG. 2B is a cross-sectional view of a portion of an optical
element and conductive material according to some embodiments.
[0017] FIG. 3A is a perspective view of a portion of an optical
element and a solar cell coupled thereto according to some
embodiments.
[0018] FIG. 3B is a perspective view of a portion of an optical
element and a solar cell coupled thereto according to some
embodiments.
[0019] FIG. 4 is a flow diagram of a method according to some
embodiments.
[0020] FIG. 5A is a perspective view of a transparent optical
element according to some embodiments.
[0021] FIG. 5B is a cross-sectional view of a transparent optical
element according to some embodiments.
[0022] FIG. 6A is a perspective view of a transparent optical
element with reflective material disposed thereon according to some
embodiments.
[0023] FIG. 6B is a cross-sectional view of a transparent optical
element with reflective material disposed thereon according to some
embodiments.
[0024] FIG. 7A is a perspective view of an optical element with an
electrical isolator disposed thereon according to some
embodiments.
[0025] FIG. 7B is a cross-sectional view of an optical element with
an electrical isolator disposed thereon according to some
embodiments.
[0026] FIG. 8A is a perspective view of an optical element with
conductive material disposed thereon according to some
embodiments.
[0027] FIG. 8B is a cross-sectional view of an optical element with
conductive material disposed thereon according to some
embodiments.
[0028] FIG. 9 is a cross-sectional view of an optical element and a
solar cell according to some embodiments.
DETAILED DESCRIPTION
[0029] The following description is provided to enable any person
in the art to make and use the described embodiments and sets forth
the best mode contemplated for carrying out some embodiments.
Various modifications, however, will remain readily apparent to
those in the art.
[0030] FIG. 1 is a flow diagram of process 100 according to some
embodiments. Process 100 may be performed by any combination of
machine, hardware, software and manual means.
[0031] Initially, at S110, a first material is thermal sprayed onto
an optical element. The first material may comprise any material
that is capable of being thermally-sprayed. Thermal spraying the
first material may include heating a powder to a molten state and
spraying the molten powder onto the optical element. The molten
powder then cools on the optical element to produce a solid layer
of material. In some embodiments, a stencil may be applied to the
optical element before spraying the molten powder onto the optical
element. The first material is therefore deposited in a pattern
defined by the stencil.
[0032] The thermal spraying may be performed using a known twin
wire arc process in a case that the first material is a metal.
Plasma spray techniques may be employed at S110 if the first
material is a metal or a ceramic. Moreover, if the first material
is a polymer (e.g., polyester, epoxy, polyurethane, etc.), the
first material may be powder coated onto the optical element at
S110. Accordingly, the term thermal spraying encompasses at least
twin wire arcing, plasma spraying (e.g., hot, cold, assisted), and
powder coating.
[0033] Thermal spraying the first material onto the optical element
may comprise spraying the first material onto other material(s)
already deposited on the optical element. According to some
embodiments, the optical element may be configured to manipulate
and/or pass desired wavelengths of light. The optical element may
comprise any number of disparate materials and/or elements (e.g.,
lenses, reflective surfaces and optically-transparent
portions).
[0034] FIG. 2A is a perspective view of apparatus 200 according to
some embodiments, and FIG. 2B is a cross-sectional view of
apparatus 200 as shown in FIG. 2A. Apparatus 200 includes optical
element 220 and conductive material 210 sprayed thereon according
to some embodiments of S110. FIGS. 2A and 2B show only a portion of
apparatus 200 in order to illustrate that apparatus 200 may exhibit
any suitable shape or size.
[0035] Conductive material 210 may comprise any combination of one
or more currently- or hereafter-known conductors, including but not
limited to copper, gold and nickel. A thickness of material 210 on
optical element 220 might not be as uniform as shown in FIG.
2B.
[0036] A solar cell is coupled to the optical element at S120. The
coupling at S120 may comprise coupling the solar cell to other
material(s) already deposited on the optical element. For example,
an electrical contact of the solar cell may be coupled to
conductive material deposited on the optical element. Such a
coupling may form an electrical and a mechanical interconnection
between the conductive material and the solar cell. Various
flip-chip bonding techniques may be employed in some embodiments to
couple an electrical contact of the solar cell to conductive
material deposited on the optical element.
[0037] FIG. 3A is a perspective view of apparatus 200 after S120
according to some embodiments. FIG. 3B is a cross-sectional view
corresponding to FIG. 3A. Solder bumps 305 of solar cell 300 are
coupled to conductive material 210. Solder bumps 305 may also be
respectively coupled to unshown terminals of solar cell 300.
[0038] Solar cell 300 may comprise a solar cell (e.g., a III-V
cell, II-VI cell, etc.) for receiving photons from optical element
220 and generating electrical charge carriers in response thereto.
In this regard, some embodiments include an opening through
dielectric conductive material 210 through which solar cell 300 may
receive light from optical element 220.
[0039] FIG. 4 is a flow diagram of process 400 according to some
embodiments. Process 400 may be performed by any combination of
machine, hardware, software and manual means.
[0040] Process 400 begins at S410, at which an optical element is
obtained. The optical element may be composed of any suitable
material or combination of materials. The optical element may be
created using any combination of devices and systems that is or
becomes known.
[0041] FIG. 5A is a perspective view of optical element 500 created
at S410 according to some embodiments, and FIG. 5B is a
cross-sectional view of element 500. Optical element 500 may be
molded from low-iron glass at S410 using known methods.
Alternatively, separate pieces may be glued or otherwise coupled
together to form element 500. Optical element 500 may comprise an
element of a solar concentrator according to some embodiments.
[0042] Element 500 includes convex surface 510, pedestal 520, and
concave surface 530. The purposes of each portion of element 500
during operation according to some embodiments will become evident
from the description below.
[0043] A reflective material is deposited on the optical element at
S420. The reflective material may be intended to create one or more
mirrored surfaces. Any suitable reflective material may be used,
taking into account factors such as but not limited to the
wavelengths of light to be reflected, bonding of the reflective
material to the optical element, and cost. In some embodiments, the
reflective material may include a mirror coating, a dielectric
enhancement coating, and/or a protective dielectric or polymer
paint coating. The reflective material may be deposited by
sputtering or other physical vapor deposition, liquid deposition,
etc.
[0044] FIGS. 6A and 6B show perspective and cross-sectional views,
respectively, of optical element 500 after some embodiments of
S420. Reflective material 540 is deposited on convex surface 510
and concave surface 530. Reflective material 540 may comprise
sputtered silver or aluminum. The vertical and horizontal surfaces
of pedestal 520 may be masked at S420 such that reflective material
540 is not deposited thereon, or otherwise treated to remove any
reflective material 540 that is deposited thereon.
[0045] Next, at S430, a polymer is powder-coated onto the optical
element. The polymer may comprise an electrical insulator, and the
powder-coating may proceed according to any method that is or
becomes known. The polymer may act as a mechanical buffer layer
between the reflective material and conductive material. This
buffer layer can also be deposited by other means such as spraying,
dipping or lamination. According to some embodiments, other
suitable insulators such as any dielectrics, polyester, epoxy and
polyurethane are powder-coated onto the optical element at
S430.
[0046] Some embodiments of S430 are depicted in FIGS. 7A and 7B.
Polymer 550 is deposited on convex surface 510 or, more
particularly, on reflective material 540. S615 may be executed such
that polymer 550 is not deposited on the vertical and horizontal
surfaces of pedestal 520. According to the illustrated embodiment,
polymer 550 is not deposited on concave surface 530 (i.e., on
reflective material 540 deposited on concave surface 530).
[0047] Returning to process 400, a stencil is placed on the optical
element at S440 and a molten metal powder is sprayed on the stencil
and the optical element at S450. The stencil may comprise a
mechanical, hard or soft tooling. The stencil may cover portions of
the previously-deposited polymer that are not to receive the molten
metal powder. The molten metal powder may be composed of any
combination of one or more metals (e.g., nickel, copper).
[0048] FIG. 8A is a perspective view and FIG. 8B is a
cross-sectional view of optical element 500 after S450 according to
some embodiments. Conductive material 560 covers pedestal 520 and
portions of insulator 550. Conductive material 570 is also sprayed
at S450 and also covers portions of insulator 550. A stencil in the
shape of the illustrated gap between conductive material 560 and
conductive material 570 was placed at S440. The gap may facilitate
electrical isolation between conductive material 560 and conductive
material 570.
[0049] Aperture 565 may comprise an exit window for light entering
element 500. The stencil placed at S440 may also define aperture
565. Such a stencil may comprise a mechanical, a liquid or a solid
mask which is removed (i.e., peeled or dissolved) after S450.
[0050] Although conductive materials 560 and 570 appear to extend
to a uniform height above element 500, this height need not be
uniform. Conductive materials 560 and 570 may create a conductive
path for electrical current generated by a photovoltaic (solar)
cell coupled to element 500. Conductive material 560 and conductive
material 570 may also, as described in U.S. Patent Application
Publication No. 2006/0231133, electrically link solar cells of
adjacent solar concentrators in a solar concentrator array.
[0051] An electrical contact of a solar cell is coupled to the
metal sprayed onto the optical element at S460. The electrical
contact may comprise a solder bump, and any number of intermediate
conductive elements such as various layers of bonding pads may be
used to couple the electrical contact to the exposed portion.
Coupling the electrical contact to the metal may comprise any
flip-chip bonding techniques that are or become known. For example,
the electrical contact may be placed on the metal using a
pick-and-place machine, and the optical element and solar cell may
be placed in a reflow oven to melt and subsequently cool the
electrical contact.
[0052] FIG. 9 shows solder bumps 910 of solar cell 900 coupled to
conductive material 560. Window 920 of solar cell 900 covers an
optically-active area of solar cell 900. Accordingly, solder bumps
910 are coupled to conductive material 560 in some embodiments such
that the optically-active area is aligned with aperture 565.
[0053] Apparatus 500 of FIG. 9 may generally operate in accordance
with the description of aforementioned U.S. Patent Application
Publication No. 2006/0231133. With reference to FIG. 9, solar rays
enter surface 598 and are reflected by reflective material 540
disposed on convex surface 510. The rays are reflected toward
reflective material 540 on concave surface 530, and are thereafter
reflected toward aperture 565. The reflected rays pass through
aperture 565 and are received by window 920 of solar cell 900.
Those skilled in the art of optics will recognize that combinations
of one or more other surface shapes may be utilized to concentrate
solar rays onto a solar cell.
[0054] Solar cell 900 receives a substantial portion of the photon
energy received at surface 598 and generates electrical current in
response to the received photon energy. The electrical current may
be passed to external circuitry (and/or to similar
serially-connected apparatuses) through conductive material 560 and
conductive material 570. In this regard, solar cell 900 may also
comprise an electrical contact electrically coupled to conductive
material 570. Such a contact would exhibit a polarity opposite to
the polarity of the contacts to which solder bumps 910 are
coupled.
[0055] The several embodiments described herein are solely for the
purpose of illustration. Embodiments may include any currently or
hereafter-known versions of the elements described herein.
Therefore, persons in the art will recognize from this description
that other embodiments may be practiced with various modifications
and alterations.
* * * * *