Abstract:
A photovoltaic module with at least one conductor extending along at least a portion of the peripheral edge of the module. A colored opaque edge seal extends over and in contact with at least a portion of the at least one conductor, to mask the appearance of the at least one conductor visible through a substrate. A method of forming the module is also described.

Description:
CLAIM OF PRIORITY 
       [0001]    This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional. Patent Application Ser. No. 61/521,431 filed on Aug. 9, 2011, which is hereby incorporated by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    Embodiments of the invention relate to the field of photovoltaic (PV) module design and, more particularly, to PV modules and methods of manufacturing. 
       BACKGROUND OF THE INVENTION 
       [0003]    A PV module (also known as a solar module or a solar panel) is a device that converts the energy of sunlight directly into electricity by the photovoltaic effect. A PV module includes at least one PV cell, also known as a solar cell, for example, a crystalline silicon cell or a thin-film cell. The PV cells convert sunlight into electrical energy and are typically formed between the front and back covers of the PV module. 
         [0004]      FIGS. 1A and 1B , respectively show a top down and cross-sectioned view of a portion of a PV module  100 . A PV module can include a plurality of layers of various materials formed between the front  170  and back  150  covers of the PV module. The plurality of layers can include, for example, an active material layer. The active material layer is formed of one or more layers of semiconductor material such as amorphous silicon (a-Si), copper indium gallium diselenide (CIGS), cadmium telluride (CdTe), cadium sulfide (CdS) or any other suitable photoconversion material or combination of these materials. The front  170  and back  150  covers protect the plurality of layers of the PV cells from moisture penetration, physical damage, and other environmental hazards. The front  170  and back  150  covers can be made of a transparent material such as glass, to allow light to pass through to the active material layer of the cell. The PV module  100  may include one or more sub-modules, and each sub-module may include a plurality of PV cells which are electrically connected. 
         [0005]    As shown in  FIGS. 1A and 1B , conventional PV module  100  may have an edge seal material (for example, a polymeric compound such as polyisobutylene (PIB) in liquid hot melt form) applied around the periphery of a module  100  between an inner planar surface  155  of a back cover  150  and an inner planar surface  175  of a front cover  170 . The edge seal  140  protects the interior of the PV module  100  from moisture and humidity penetration. The edge seal  140  is located adjacent to one or more bus bars  130  (also known as bus conductors, common conductors, photovoltaic ribbon, or buses) within module  100  which run along a peripheral edge  145  of the module and which extract the electricity generated by the at least one PV cell inside the PV module  100 . Each bus bar  130  enables electrical connection of a module to additional electrical components outside the module  100 . Each bus bar  130  has a thickness which partially or wholly extends between the back  150  and front  170  covers of the module  100 . Since the one or more bus bars  130  are formed of a shiny metal material, e.g. aluminum, copper or other metal, they can be seen through the front cover  170  as producing a metallic appearance M and contrast with an otherwise uniform dark, e.g. black, appearance of the area  120  of the module  100  containing at least one PV cell, for example. The metallic appearance M of a bus bar  130  disrupts the uniform dark appearance of PV module  100  causing some customers to request a more uniform module appearance. 
         [0006]    In an effort to make the appearance of module  100  more uniform across the entire front cover  170 , a trim strip or black tape has been applied over one or more bus bars  130  to hide their metallic appearance. The trim strip is typically made of pigmented polyester or other inert polymer or fabric. This solution requires, however, additional material and additional manufacturing processing steps resulting in increased fabrication time and cost. Accordingly, there is needed a less costly, more efficient method of masking the metallic bus bars of a PV module to confer a uniform dark appearance to the PV module. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]      FIG. 1A  illustrates a cut away top view of an existing PV module; 
           [0008]      FIG. 1B  illustrates a cross-sectioned view of the PV module of  FIG. 1A  taken along section A-A; 
           [0009]      FIG. 2A  illustrates a cut away top view of one embodiment of a PV module; 
           [0010]      FIG. 2B  illustrates a cross-sectioned view of the PV module of  FIG. 2A  taken along section B-B; 
           [0011]      FIG. 3A  illustrates a cut away top view of another embodiment of a PV module; 
           [0012]      FIG. 3B  illustrates a cross-sectioned view of the PV module of  FIG. 3A  taken along section C-C; and 
           [0013]      FIG. 3C  illustrates a cut away perspective view of the PV module of  FIG. 3A . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and which illustrate specific embodiments of the invention. These embodiments are described in sufficient detail to enable those of ordinary skill in the art to make and use them. It is also understood that structural, logical, or procedural changes may be made to the specific embodiments disclosed without departing from the spirit and scope of the invention. 
         [0015]    Referring now to the drawings, where like elements are designated by like reference numerals,  FIG. 2A  illustrates a cut away top view of a portion of a PV module  200  according to a disclosed embodiment. The edge seal  240  covers at least a portion of one or more bus bars  130 , which would otherwise be visible through the front cover  170 , to confer a substantially uniform dark, e.g. black, appearance X of the PV module preferred by customers.  FIG. 2B  illustrates a cross-sectioned view of  FIG. 2A  taken along section B-B. 
         [0016]    During manufacturing, the plurality of PV cells (or at least one PV cell) formed in area  120  can be fabricated by any process known in the art. The plurality of PV cells and the edge seal  240  are sandwiched between the aligned front cover  170  and back cover  150  which define the top outer surface and the bottom outer surface, respectively, of PV module  200 . Front cover  170  has a width and a length and back cover  150  has substantially the same width and length as the front cover  170 . PV cells can be connected in series, parallel, or a combination thereof depending on the desired electrical output from PV module  200 . The plurality of PV cells within a module  200  are connected in series by forming interconnects between adjacent cells, for example. Each bus bar  130  may be formed of tin, copper, aluminum, silver, gold, nickel, their alloys, or any other suitable conductive material or combination of such materials. Each bus bar  130  can function as one of a common positive and negative conductor, electrically connected to the first PV cells in the series or the last PV cells in the series, for example. Each bus bar  130  may pass through a hole provided in back cover  150  and be covered by a cord plate which allows external conductors to be electrically connected with a respective bus bar  130 , or each bus bar  130  may extend outwardly of an edge of a module  200  between the front  170  and back  150  covers. The PV module  200  can include any suitable arrangement of series and parallel connections between the plurality of interior PV cells. If the PV module  200  is divided into two sub-modules, a first bus bar may serve as a common ground for both a first sub-module and a second sub-module. A second and third bus bar may serve as a positive bus bar for the first and second sub-modules, respectively. 
         [0017]    Edge seal  240  protects PV module  200  from moisture intrusion, foreign substances, and other environmental hazards. Edge seal  240  can also serve as an adhesive, that bonds the front cover  170  to the back cover  150 . Polyisobutylene (PIB), also known as butyl rubber, is a common edge seal material, but other examples of edge seals include opaque polymeric compounds. The edge seal material is usually dyed black, but may contain any colorant to match the overall color of the area  120  visible through the front cover  170 . 
         [0018]    The edge seal material that forms the edge seal  240  may be applied in liquid hot melt form, in tape form, or by any other known technology. The liquid hot melt edge seal material may cool to a solid state when the front cover  170  and the back cover  150  are combined during manufacturing. The cured edge seal material may be applied in liquid hot melt form during manufacturing using a hot melt process which may include a hot melt dispensing device, for example. The hot melt dispensing device may dispense the liquid edge seal material through an applicator attached to a hose, such that the liquid edge seal material is pumped from a dispensing pump connected to an edge seal material container. The liquid edge seal material may include a desiccant material. Additional details related to hot melt technology and use of an edge seal with a desiccant are provided, for example, in U.S. Patent Publ. No. 2009/0159117 to Ferri et al., the disclosure of which is incorporated by reference in its entirety herewith. The hot melt process allows manufacturers to vary the thickness of the edge seal. 
         [0019]    In  FIGS. 2A and 2B , one or more bus bars  130  abut the area  120  containing a plurality of PV cells (or at least one PV cell) and seal  240  contacts and completely covers at least a portion of one or more bus bars  130  otherwise visible through the front cover  170 . Each bus bar  130  extends along at least a portion of a peripheral edge  145  of module  200 . The edge seal  240  extends around at least a portion of the perimeter P of the PV module  200 . The edge seal  240  also extends inwardly from a peripheral edge  145  of the module  200  a distance D (which also illustrates the width of the edge seal  240 ) of between about 7 mm and about 40 mm. The thickness of the edge seal  240  (measured between the interior surfaces of the front  170  and back  150  covers) may be between about 0.3 mm and about 1.0 mm. The width and thickness of the edge seal  240  are not limited however and, thus, the edge seal may have any width and thickness, depending on the specific characteristics of the PV module  200  and as long as the edge seal extends over at least a portion of one or more bus bars  130  visible through the front cover  170 . 
         [0020]    Although  FIGS. 2A and 2B  illustrate a back cover  150  adjacent to the area  120  containing the plurality of PV cells (or at least one PV cell), this is not limiting For example, additional layers may be inserted between the back cover  150  and the plurality of PV cells formed in area  120 . In particular, an interlayer may be formed adjacent to the area  120 . The interlayer may include a material selected from a group consisting of ethylene (EVA), polyvinyl butyral (PVB), polydimethylsiloxane (PDMS), butyl/PIB, polyolefin, thermoplastic polyurethane (TPU), polyurethane, epoxy, silicone and ionomer. The interlayer may serve as a moisture barrier, an electrical insulator between area  120  and the back cover  150 , and/or a bonding agent that attaches the back cover  150  to the module  200  through a lamination process during manufacturing, for example. 
         [0021]      FIG. 3A  illustrates a cut away top view of a portion of a PV module  300  according to a disclosed embodiment in which one or more bus bars  330  extend along at least a portion of a peripheral edge  145  of module  300  but do not abut the area  120 .  FIG. 3B  shows a cross-sectioned view of  FIG. 3A  taken along section C-C and  FIG. 3C  illustrates a cut away perspective view of a portion of PV module  300 . Seal  340  extends inwardly from a peripheral edge  145  of the module  300  a distance D. Because one or more bus bars  330  do not abut the area  120 , seal  340  also extends between said area  120  and a bus bar  330 . 
         [0022]    The edge seal is used to conceal one or more bus bars of any PV module, e.g. crystalline, polycrystalline, CIGS, where the metallic appearance of a bus bar visible through the front cover  170  disrupts the uniform dark appearance of the PV module. 
         [0023]    While embodiments have been described in detail, it should be readily understood that the invention is not limited to the disclosed embodiments. Rather the embodiments can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described. Although certain features have been described with some embodiments of the edge seal, such features can be employed in other disclosed embodiments of the edge seal as well. Accordingly, the invention is not limited by the foregoing embodiments, but is only limited by the scope of the appended claims.