Solar panel including a low moisture vapor transmission rate adhesive composition

Abstract

A solar panel including a front panel; a photovoltaic material layer deposited either directly on the front panel or directly on an anti-reflective coating formed between the front panel and the photovoltaic material layer; a backing panel; and an adhesive layer disposed between and adhering together the photovoltaic material layer and the backing panel, in which the adhesive layer comprises an adhesive composition, the adhesive composition comprising a low MVTR polymer or copolymer and a silane-modified polymer or copolymer. In another embodiment, the solar panel includes module wire openings which are filled by an adhesive composition comprising a low MVTR polymer or copolymer and a silane-modified polymer or copolymer. A method of making the solar panel is provided.

1 . A solar panel comprising: 
 a front panel comprising glass;    a photovoltaic material layer deposited either directly on the front panel or directly on an anti-reflective coating formed between the front panel and the photovoltaic material layer;    a backing panel; and    an adhesive layer adhering the photovoltaic material layer to the backing panel,    wherein the adhesive layer comprises an adhesive composition, the adhesive composition comprising a low MVTR polymer or copolymer and a silane-modified polymer or copolymer, wherein the low MVTR polymer or copolymer is different from the silane-modified polymer or copolymer.    
     
     
         2 . The solar panel of  claim 1 , wherein the silane-modified polymer or copolymer is crosslinked as a result of exposure to atmospheric oxygen or moisture.  
     
     
         3 . The solar panel of  claim 1 , wherein the adhesive composition has a MVTR less than about 3 grams per square meter per day.  
     
     
         4 . The solar panel of  claim 1 , wherein the low MVTR polymer or copolymer comprises at least one of a polyisobutylene, an isobutylene-isoprene copolymer, an isobutylene-isoprene-divinylbenzene copolymer, a chlorinated or brominated butyl rubber, an isobutylene-brominated p-methylstyrene copolymer, an isobutylene-p-methylstyrene copolymer, a chlorosulfonated polyethylene, an ethylene-alkyl (meth)acrylate copolymer, an acrylonitrile-butadiene copolymer, polychloroprene, or a mixture of two or more thereof.  
     
     
         5 . The solar panel of  claim 1 , wherein the silane-modified polymer or copolymer comprises a homopolymer of propylene, or a copolymer of propylene and at least one C 2 -C 8  α-olefin.  
     
     
         6 . The solar panel of  claim 1 , wherein the silane-modified polymer or copolymer comprises a copolymer of propylene and one or more of maleic anhydride or an alkyl (meth)acrylate.  
     
     
         7 . The solar panel of  claim 1 , wherein the low MVTR polymer or copolymer is polyisobutylene and the silane-modified polymer is silane-modified amorphous polypropylene.  
     
     
         8 . The solar panel of  claim 1 , wherein the adhesive composition further comprises a cross-linking initiator capable of initiating cross-linking between silyl groups on the silane-modified polymer or copolymer.  
     
     
         9 . The solar panel of  claim 1 , wherein the silane-modified polymer or copolymer comprises one or more of a silane-modified amorphous α-olefin polymer or copolymer, a silane-crosslinkable halogenated polymer composition, and a silane grafted copolymer of a monoolefin and a vinyl aromatic monomer.  
     
     
         10 . The solar panel of  claim 1 , wherein the silane-modified polymer or copolymer is provided as a silane-modified amorphous α-olefin polymer or copolymer comprising silyl groups having a structure (I):  
         —Si(OR 1 ) n (R 2 ) m   (I)  
       wherein each of R 1  and R 2  independently is a C 1 -C 8  branched or unbranched alkyl group, n=1 to 3, m=0 to 2, and m+n=3, and the —Si is bonded directly to a carbon atom of the polymer or copolymer.  
     
     
         11 . The solar panel of  claim 1 , wherein the silane-modified polymer or copolymer is provided as a silane-crosslinkable halogenated polymer composition comprising the reaction product of a mixture of 100 parts by weight of a halogenated polymer and about 0.1 to about 20 parts by weight of an amino group-containing silane compound having the following general structure (II):  
         RHNR′Si(OR″) 3   (II)  
       wherein R is hydrogen, an alkyl or a phenyl group, R′ is an alkylene group, OR″ is an alkoxy or alkoxyalkoxy group having 1 to 6 carbon atoms, wherein the N atom is bonded to a position on the polymer replacing a halogen.  
     
     
         12 . The solar panel of  claim 1 , wherein the silane-modified polymer or copolymer is provided as a silane grafted copolymer comprising the reaction product of at least 50 mole % of at least one C 3 -C 7  monoolefin and from about 0.1 up to 50 mole % of at least one vinyl aromatic monomer, in which the silane has the general structure (III):  
         RR′SiY 2   (III)  
       wherein R represents a monovalent olefinically unsaturated hydrocarbon or hydrocarbonoxy radical reactive with the free radical sites produced on the backbone polymer, Y represents a hydrolyzable organic radical and R′ represents an alkyl or aryl radical or a Y radical, wherein the R radical becomes bonded to the polymer or copolymer.  
     
     
         13 . The solar panel of  claim 1 , wherein the adhesive composition further comprises an adhesion promoter comprising one or more of a silane, a titanate, a zirconate or a zirco-aluminate.  
     
     
         14 . The solar panel of  claim 1 , wherein the adhesive composition further comprises a cross-linking catalyst.  
     
     
         15 . The solar panel of  claim 1 , wherein the adhesive composition further comprises a plasticizer.  
     
     
         16 . The solar panel of  claim 1 , wherein the adhesive composition further comprises a tackifying resin.  
     
     
         17 . The solar panel of  claim 1 , wherein the solar panel comprises module wire openings extending through at least one of the photovoltaic material layer or the backing panel and a module wire adhesive sealing the module wire openings, wherein the module wire adhesive comprises a low MVTR polymer or copolymer and a silane-modified polymer or copolymer, the module wire adhesive having a different composition than the composition of the adhesive.  
     
     
         18 . The solar panel of  claim 1  wherein the photovoltaic material comprises a vapor deposited photovoltaic material.  
     
     
         19 . The solar panel of  claim 1  wherein the adhesive composition extends to outer edges of the solar panel, is exposed to the atmosphere at the outer edges, and the low MVTR polymer or copolymer provides a barrier to moisture ingress at the outer edges.  
     
     
         20 . A method of fabricating a solar panel comprising a photovoltaic material layer and a backing panel, the method comprising: 
 (a) providing a front panel suitable for use in a solar panel;    (b) vapor depositing a photovoltaic material layer on the front panel;    (c) forming an adhesive composition having a low moisture vapor transmission rate by combining a low MVTR polymer or copolymer with a silane-modified polymer or copolymer, wherein the low MVTR polymer or copolymer is different from the silane-modified polymer or copolymer;    (d) adhering the photovoltaic material layer to the backing panel using the adhesive composition; and    (e) cross-linking the silane-modified polymer or copolymer.    
     
     
         21 . The method of  claim 20 , wherein step the adhesive composition further comprises a cross-linking catalyst.  
     
     
         22 . The method of  claim 20 , wherein upon cross-linking, the silane-modified polymer or copolymer forms a network with the low MVTR polymer or copolymer interpenetrating the network.  
     
     
         23 . The method of  claim 20 , wherein the front panel comprises glass.  
     
     
         24 . The method of  claim 20 , wherein step (d) comprises applying a layer of the adhesive composition to the photovoltaic material layer.  
     
     
         25 . The method of  claim 20 , wherein the solar panel comprises module wire openings extending through at least one of the photovoltaic material layer or the backing panel, and the method further comprises applying the low MVTR adhesive composition to the module wire openings.  
     
     
         26 . The method of  claim 20 , wherein the cross-linking is initiated by exposure of the adhesive composition to atmospheric oxygen or moisture.  
     
     
         27 . The method of  claim 20 , wherein the adhesive composition has a MVTR less than about 3 grams per square meter per day.  
     
     
         28 . The method of  claim 20  wherein the vapor depositing is by one or more of sputtering, physical vapor deposition, or chemical vapor deposition.  
     
     
         29 . The method of  claim 20  wherein the adhesive composition is applied to extend to outer edges of the solar panel, is exposed to the atmosphere at the outer edges, and the low MVTR polymer or copolymer provides a barrier to moisture ingress at the outer edges.  
     
     
         30 . A solar panel comprising: 
 a front panel;    a photovoltaic material layer vapor deposited either directly on the front panel or directly on an anti-reflective coating formed between the front panel and the photovoltaic material layer;    a backing panel; and    an adhesive layer adhering the photovoltaic material layer to the backing panel,    wherein the adhesive layer comprises an adhesive composition, the adhesive composition comprising a low MVTR polymer or copolymer and a silane-modified polymer or copolymer, wherein the low MVTR polymer or copolymer is different from the silane-modified polymer or copolymer.    
     
     
         31 . The solar panel of  claim 30  wherein the front panel comprises glass.  
     
     
         32 . The solar panel of  claim 30  wherein the adhesive composition extends to outer edges of the solar panel, is exposed to the atmosphere at the outer edges, and the low MVTR polymer or copolymer provides a barrier to moisture ingress at the outer edges.