Patent Application
20080083449
The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more embodiments of the present invention and, together with the detailed description, serve to explain the principles and implementations of the invention.
In the drawings:
a is a head-on view of the opening of the outer transparent barrier detailing the outline of the edge of the opening.
b is a head-on view of the cap detailing the recess that resides thereon.
Embodiments of the present invention are described herein in the context of a hermetically-sealed solar cell architecture using a molten glass frit. Those of ordinary skill in the art will realize that the following detailed description of the present invention is illustrative only and is not intended to be in any way limiting. Other embodiments of the present invention will readily suggest themselves to such skilled persons having the benefit of this disclosure. Reference will now be made in detail to implementations of the present invention as illustrated in the accompanying drawings. The same reference indicators will be used throughout the drawings and the following detailed description to refer to the same or like parts.
In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer's specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking of engineering for those of ordinary skill in the art having the benefit of this disclosure.
A cap 30 is provided to mate to the end of the outer open end of the transparent barrier 26a. When the cap 30 is conjoined to the outer transparent barrier 26a, this completes the seal of the photovoltaic apparatus, isolating the internal volume of the photovoltaic apparatus 28 from an external environment.
a is a head-on view of the opening of the outer transparent barrier 26a, detailing the outline of the edge of the opening.
In
In
In
In
In one manner, the dual-sided seal substantially illustrated in
The apparatus need not be limited to unitary transparent or elongated casings, as previously shown. In fact, the dual-sided seal and the ability to form an environmental seal such as described can be applied to conventional photovoltaic assemblies. Take for example the apparatus as depicted in
The heating and melting of the sealant can be accomplished in many ways. The temperature can be increased to a value that will enable the sealant to soften and/or melt. Heat can be applied by methods such as direct contact with a hot surface, by inductively heating up a metal part, by contact with flame or hot air, or through absorption of light from a laser. In one embodiment, the sealant can be melted outside the recess, then added to the recess while in an at least partially molten stage.
In one embodiment, the sealant is glass. In another, the glass is vitreous in nature. Other potential sealants can include a metallic solder-that adheres to glass, other low-temperature melting point metals, or ceramics that have a high environmental sealant characteristic.
An outer transparent barrier 26, as depicted in the Figures, is any transparent barrier that seals a solar device and provides support and protection to the solar cell. The size and dimensions of outer transparent barrier 26a are determined by the size and dimension of individual device or devices housed within it. Outer transparent barrier 26a may be made of glass, plastic or any other suitable material. Examples of materials that can be used to make transparent tubular casing 310 include, but are not limited to, glass (e.g., soda lime glass, as an example), acrylics such as polymethylmethacrylate, polycarbonate, fluoropolymer (e.g., Tefzel or Teflon), polyethylene terephthalate (PET), Tedlar, or some other suitable transparent material.
In some specific embodiments, outer transparent barrier 26 is made of glass. The present invention contemplates a wide variety of glasses for transparent tubular or transparent elongated casing, some of which are described in this section and others of which are know to those of skill in the relevant arts. Common glass contains 20 about 70% amorphous silicon dioxide (SiO2), which is the same chemical compound found in quartz, and its polycrystalline form, sand. In some embodiments, the properties of common glass are modified, or even changed entirely, with the addition of other compounds or heat treatment.
As previously mentioned, in some embodiments, outer transparent barrier 26 is made of clear plastic. Plastics can be a cheaper alternative to glass. However, plastic material is, in general, less stable under heat, has less favorable optical properties and does not prevent molecular water from penetrating through outer transparent barrier 26a. The last factor, if not rectified, can damage the photovoltaic devices and can substantially reduce their lifetime.
A wide variety of materials can be used in the production of outer transparent barrier 26, including, but not limited to, a urethane polymer, an acrylic polymer, polymethylmethacrylate (PMMA), a fluoropolymer, silicone, poly-dimethyl siloxane (PDMS), silicone gel, epoxy, ethyl vinyl acetate (EVA), perfluoroalkoxy fluorocarbon (PFA), nylon/polyamide, cross-linked polyethylene (PEX), polyolefin, polypropylene (PP), polyethylene terephtalate glycol (PETG), polytetrafluoroethylene (PTFE), thermoplastic copolymer (for example, ETFE®, which is a derived from the polymerization of ethylene and tetrafluoroethylene: TEFLON® monomers), polyurethane urethane, polyvinyl chloride (PVC), polyvinylidene fluoride (PVDF), Tygon®, Vinyl, and Viton®, or any combination or variation thereof.
The outer transparent barrier 26 can comprise a plurality of transparent tubular or transparent elongated casing layers. In some embodiments, each transparent tubular casing is composed of a different material.
The outer transparent barrier 26 can be of any geometry, although in this diagram it is cylindrical in nature. Other cross-sections of the outer barrier can be of any shape or any number of sides, including having a cross-section of any n-sided polygon. Such sides of a polygonal cross-section need not be congruent in length with one another. In particular, this can be applied generally elongated to multi-wall or (in the case of a purely arcuate barrier) omni-wall outer transparent barriers. Generally, the discussion can be applied to any transparent elongated casing that provides support and protection to solar cells. Even more generally, this specification should be considered as applying to the general rectangular construction of a conventional photovoltaic assembly. Accordingly, all these should be considered as within the scope of the systems and methods of the present disclosure.
The shape of the photovoltaic in the accompanying diagrams can be of any shape or size as long as it fits into a sleeve-like outer shell. In addition, although only one device is shown, the diagram and description should be construed to cover any number of photovoltaic devices within the sleeve-like outer shell.
Depending upon the materials used, helium leak rates of 10−9 cc/sec, 10−8 cc/sec, 10−7 cc/sec, 10−6 cc/sec, 10−5 cc/sec (all at standard pressure and temperature) can be achieved. Accordingly ranges of 10−5 cc/sec −10−7 cc/sec, 10−6 cc/sec −10−8 cc/sec, 10−7 cc/sec −10−9 cc/sec should all be considered as disclosed. A leak rate of less than 10−8 cc/sec. should be considered as a hermetic seal.
In some embodiments, the seal formed between sealant cap 30 and the wall of the outer transparent barrier 26a has a water vapor transmission rate (WVTR) of 10−4 g/m2·day or less. In some embodiments, the seal formed between sealant cap 30 and the wall of the outer transparent barrier 26a has a water vapor transmission rate (WVTR) of 10-5 g/m2·day or less. In some embodiments, the seal formed between sealant cap 30 and the wall of the outer transparent barrier 26a has a WVTR of 10-6 g/m2·day or less. In some embodiments, the seal formed between sealant cap 30 and the wall of the outer transparent barrier 26a has a WVTR of 10-7 g/m2·day or less. In some embodiments, the seal formed between sealant cap 30 and the wall of the outer transparent barrier 26a has a WVTR of 10-8 g/m2·day or less.
In some embodiments, the seal between sealant cap 30 and the wall 34 of outer transparent barrier 26a is accomplished using a glass, powder glass, or more generally, a ceramic material. In preferred embodiments, this glass or ceramic material has a melting temperature between 200° C. and 450° C. In embodiments, this glass or ceramic material has a melting temperature between 300° C. and 450° C. In embodiments, this glass or ceramic material has a melting temperature between 350° C. and 400° C.
An assembly for producing photovoltaic electricity is contemplated. The assembly is made of an outer assembly having at least one portion transparent to light energy, and defines an inner assembly volume. The outer assembly can be made of a first structural member having an opening to an external environment, where the opening is defined by at least one edge. The outer assembly also has a second structural member with a recess that corresponds to the edge at the opening. In this manner the edge of the first structural member conjoins with the corresponding recess of the second structural member, and the edge is conjoined to the corresponding recess with a seal. A photovoltaic device is disposed within the inner assembly volume. The photovoltaic device is operable to receive the light and produce electric energy in response to it.
The first structural member can be made with a transparent member. In one case, the first structural member is an elongated structure. In a more specific case the first structural member is a tubular structure. The first structural member can have an arcuate feature. Or, the first structural member can be characterized as having a cross-section of an n-sided polygon, where n is an integer greater than 2. The second structural member can be a metal cap.
The second structural member can be made with a transparent member. In one case, the second structural member is an elongated structure. In a more specific case the second structural member is a tubular structure. The second structural member can have an arcuate feature. Or, the second structural member can be characterized as having a cross-section of an n-sided polygon, where n is an integer greater than 2. The first structural member can be a metal cap.
An assembly for producing photovoltaic electricity can also be characterized as having an outer assembly having at least one portion transparent to light energy. The outer assembly can be characterized by having an end. The end can be characterized by an edge that bounds an opening, where the edge has at least a plurality of sides.
The assembly also has a cap characterized by having a recess disposed in its surface. The recess corresponds to the edge, where the cap is operable to fit to the elongated outer assembly by placing the edge within the recess.
The cap is affixed to the elongated outer assembly with a sealant, where the cap and elongated outer assembly define a hermetically sealed inner volume. A photovoltaic device is disposed within the inner volume.
In one case, the seal between the cap and the sealant is a glass to metal seal. The seal between the outer assembly and the sealant can be a glass to glass seal.
In one case the outer assembly is characterized with a length and a width, where the length is at least three times the width of the outer assembly. The outer assembly can have an arcuate feature, or be a tubular structure. The outer assembly can also be characterized as having a cross-section of an n-sided polygon, where n is an integer greater than two.
An assembly for producing photovoltaic electricity is also considered. An elongated outer assembly having at least one portion transparent to light energy is provided. The outer assembly has an opening at the end, the opening characterized by an edge. The edge has at least a plurality of sides. The length of the outer assembly is substantially greater than a width of a cross-section of the outer assembly.
A cap having a recess disposed in its surface is also provided. The recess corresponds to the edge, and the cap is operable to fit to the elongated outer assembly by placing the edge within the recess. The cap is affixed to the elongated outer assembly with a sealant, thus forming a hermetically sealed inner volume. One or more photovoltaic devices are disposed within the inner volume, where the one or more photovoltaic devices are operable to receive the light and produce electric energy.
An assembly for producing photovoltaic electricity can be made with an outer assembly. The outer assembly has a first assembly member transparent to light energy. At the end of the outer assembly, an end structure is present that bounds an opening. A cap is provided to cover the opening.
A first structure is defined as one chosen from among the cap and the end structure. The first structure is characterized as having an edge.
A second structure is defined as the other of the cap and the end structure that is not the first structure. The second structure is characterized as having a recess disposed in it, where the recess corresponds in shape to an outline of the edge of the first structure.
The first structure is affixed to the second structure with a sealant affixed about the edge. The conjoined first structure and second structure define an inner volume. One or more photovoltaic devices are disposed within the inner volume.
The outer assembly can have a length substantially greater than a dimension of a cross-section of the outer assembly along its length. The outer assembly can comprise an arcuate feature. The outer assembly can have a polygonal cross-section.
In one case, the first structure is the end structure. In another, the first structure is the cap. The sealant can be glass.
A method of producing a photovoltaic assembly may include several steps. The method comprises a step of providing a storage member with an inner volume. The storage member has a photovoltaic device disposed within it, and an outer assembly with at least one wall. The outer assembly has an opening from an external environment to the inner volume.
Next, a sealing member is provided. A first member from either the storage member or the sealing member is characterized by a recess. A second member, being the other of the storage member or the sealing member, is characterized by an edge feature that corresponds in shape to the recess.
A sealing material is placed in the recess. The sealing material can be melted while in the recess, or it can be melted outside the recess and added to the recess. The sealant can be fully or partially melted.
The edge member is placed into the at least partially melted sealing material. Subsequent to placing the edge member into the sealing material, the sealing material is allowed to solidify about the edge member. This acts to seal the opening to the inner volume.
Thus, a photovoltaic apparatus having a hermetic seal is described and illustrated. Those skilled in the art will recognize that many modifications and variations of the present invention are possible without departing from the invention. Of course, the various features depicted in each of the figures and the accompanying text may be combined together.
Accordingly, it should be clearly understood that the present invention is not intended to be limited by the particular features specifically described and illustrated in the drawings, but the concept of the present invention is to be measured by the scope of the appended claims. It should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention as described by the appended claims that follow.
While embodiments and applications of this invention have been shown and described, it would be apparent to these skilled in the art having the benefit of this disclosure that many more modifications than mentioned above are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the appended claims.
