Patent Application
20090025784
1. Field
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.
2. Brief Description
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.
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.
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.
To address at least the foregoing, some aspects provide a method, means and/or process steps to thermal spray a first material onto an optical element, and to couple a solar cell to the optical element. Thermal spraying the first material may include spraying a molten metal powder onto the optical element. Moreover, spraying the molten metal powder onto the optical element may include placing a stencil on the optical element and spraying a molten metal powder onto the stencil and the optical element.
In some aspects, thermal spraying the first material includes powder coating a polymer onto the optical element. According to still other aspects, a reflective material is deposited on a substantially-transparent core, an insulator is deposited on the reflective material, and thermal spraying the first material includes spraying a molten metal powder onto the insulator.
In other aspects, provided are an optical element, a thermal-sprayed material disposed on the optical element, and a solar cell coupled to the optical element. The thermal-sprayed material may comprise a hardened metal powder. In further aspects, the optical element may comprise an aperture from which light may pass out of the optical element, 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.
The thermal-sprayed material may comprise a polymer. Additionally or alternatively, the optical element may comprise a substantially-transparent core, a reflective material disposed on the substantially-transparent core, and an insulator disposed on the reflective material, wherein the thermal-sprayed material is disposed on the insulator. Further to the foregoing aspect, the insulator may include a powder-coated polymer.
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.
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.
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.
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.
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.
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).
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
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.
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.
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.
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.
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.
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.
Some embodiments of S430 are depicted in
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).
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.
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.
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.
Apparatus 500 of
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.
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.
The present application 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.
| Number | Date | Country | |
|---|---|---|---|
| 60899150 | Feb 2007 | US |
