WO2013078013A1 - Integrated films for use in solar modules - Google Patents

Abstract

This disclosure generally relates to films capable of use in electronic device modules and to electronic device modules including such films. The disclosure also generally relates to materials for use in such films.

Description

INTEGRATED FILMS FOR USE IN SOLAR MODULES

Field of the Disclosure

This disclosure generally relates to films capable of use in a photovoltaic solar module and to photovoltaic solar modules including such films. The disclosure also generally relates to materials for use in such films.

Background

Three basic constructions of photovoltaic solar modules are commercially available. The first construction of solar module 10 is shown in Fig. 1 and includes a photovoltaic cell 20 embedded in encapsulant 30. Two protective layers (e.g., panels of glass or other suitable material) 40, 50 are positioned adjacent to the frontside and backside of the encapsulant. The encapsulant protects the fragile solar cells and adheres them to the frontside and backside protective layers. Typically, this solar module construction includes encapsulant on both sides of the solar cell. This can be accomplished, for example, by including a frontside layer of encapsulant (positioned to face the sun) and a backside layer of encapsulant (positioned furthest from the sun). Frontside encapsulant layers are preferably highly transmissive while backside encapsulant layers need not have the same level of transmissivity. Typical encapsulant layers include ethylene vinyl acetate (EVA) polymers. This construction of this type of photovoltaic solar modules is generally described in, for example, U.S. Patent Publication No. 2008/0078445.

The second construction of solar module 60 is shown in Fig. 2 and includes a photovoltaic cell 70 positioned between a single encapsulant layer 80 and a backing material 90. Solar module 60 also includes a protective layer 100 adjacent to encapsulant layer 80. As shown in Fig. 2, this solar module design includes a frontside encapsulant and no backside encapsulant. This construction of this type of photovoltaic solar module is generally described in, for example, U.S. Patent Publication No. 2008/0078445.

The third construction of solar module 110 is shown in Fig. 3 and includes a photovoltaic cell 120 positioned between a single encapsulant layer 130 and a protective layer 150. Solar module 1 10 also includes a backing layer 140 adjacent to encapsulant layer 130. As shown in Fig. 3, this solar module design includes a backside encapsulant and no frontside encapsulant. This type of construction of a photovoltaic solar module is generally described in, for example, U.S. Patent No. 5,248,349.

Backing layer 40, 90, 140 materials can include, for example, glass. Alternatively, backing layers 40, 90, 140 can be a protective backsheet. Typically, protective backsheets for use in solar modules are multi-layered films that electrically insulate the solar module and protect the solar module from the environment (e.g., moisture and dirt). Such protective backsheets typically include at least one layer including a fluoropolymer and multiple other layers including polymers (e.g., polyethene terephthalate (PET) polymers, polyethene naphthalate (PEN) polymers, polyesters, and polyamides).

Summary

The inventors of the present disclosure recognized that while the crosslinked EVA encapsulant films often have high strength, they can suffer from a relatively high water vapor transmission rate, yellowing, and possible corrosion due to release of acetic acid.

Solar panel operating temperatures have been measured as high as 1 10°C, but are typically in the range of 65-85°C. The inventors of the present application recognized that encapsulant films including thermoplastic adhesives can soften at this elevated temperature, causing creep in the panel and possibly resulting in shorting of the photovoltaic cell. These encapsulant films may also be susceptible to UV-induced breakdown, necessitating inclusion of large amounts of UV absorber, which limits the amount of incident light that can be used to power the solar cell.

The inventors of the present disclosure also recognized that the use of thermoset adhesives in encapsulant layers can suffer from slower extrusion processing speeds, causing increased

manufacturing cost.

The inventors of the present disclosure also recognized that the commonly used protective backsheet ingredients are expensive and that, in many cases, tie layers or other additional ingredients have to be provided to achieve sufficient cohesion between the individual layers in the protective backsheet. Additionally, the backsheet materials described above may not sufficiently adhere to the commonly used encapsulants, which may decrease performance and/or durability. Also, the backsheet materials described above cannot be combined in a single process step to form a multi-layer backsheet. Instead, the layers must be separately and subsequently bonded together, which increases manufacturing cost and may result in unstable interlayer bonding, which can negatively affect long term stability of the multilayer protective backsheet.

Consequently, the inventors of the present disclosure recognized a need for encapsulant films and materials that minimize the incidence of creep, shrinkage, light transmission, yellowing, corrosion, and delamination while maintaining or improving film processability and manufacturing cost. The inventors of the present disclosure have discovered encapsulant films, materials for use in such films, and solar modules including such films and materials that provide at least one of improved performance, cost, and processability. Further, the inventors of the present disclosure recognized a need for multilayer protective integrated backsheets having lower manufacturing costs without negatively affecting durability and performance. Also, the inventors of the present application recognized a need for multilayer integrated backsheets that have good adhesion both between the individual layers within the multilayer backsheet and between the backsheet and the encapsulant layer(s). The inventors of the present disclosure have discovered multilayer integrated backsheet films, materials for use in such films, and solar modules including such films and materials that provide at least one of improved performance, cost, adhesion, and processability.

Further, the inventors of the present application recognized a need for a single multilayer integrated film that can be used in a solar module as both a protective backsheet and a backside encapsulant. The inventors of the present disclosure have discovered a multilayer integrated film that can be used in a solar module as both the protective backsheet and as a backside encapsulant.

One exemplary embodiment of the present disclosure is a multilayer integrated film capable of use in a solar module including:

a backsheet portion including:

a first outer layer of a fluoropolymer with a tensile modulus of less than 100,000 psi; an intermediate layer of polyethylene terephthalate having at least two planar directions and a shrinkage of less than 1% in each planar direction when held for 15 minutes at 150°C measured in accordance with ASTM 2305-02; and

a second outer layer of an olefinic polymer of the formula CH₂=CHR", wherein R" is hydrogen or a C_n8 alkyl, and wherein the first outer layer and the second outer layer are bonded to opposing sides of the intermediate layer; and

an encapsulant portion including a polyolefin, a silane, one or more cross-linking agents, and a plasticizer.

Another exemplary embodiment of the present disclosure is a multilayer integrated film capable of use in a solar module including:

a backsheet portion including:

a first outer layer of a fluoropolymer with a tensile modulus of less than 100,000 psi an intermediate layer of a polyester having at least two planar directions and a first and second surface, wherein the intermediate layer has a shrinkage of less than about 1% in each planar direction when held for 15 minutes at 150°C measured in accordance with ASTM 2305-02; and

a second outer layer of an olefinic polymer, wherein the first outer layer and the second outer layer are bonded to opposing sides of the intermediate layer; and an encapsulant portion including a polyolefin, a silane, one or more cross-linking agents, and a plasticizer.

Another exemplary embodiment of the present disclosure is a multilayer, integrated film capable of use in a solar module, comprising: (1) a backsheet portion including one or more of a fluoropolymer, a polyester, and a polyamide; and (2) an encapsulant portion including a polyolefin, a silane, one or more cross-linking agents, and a plasticizer.

Another exemplary embodiment of the present disclosure is a multilayer, integrated film capable of use in a solar module, comprising: (1) a backsheet portion including (a) an outer layer of a fluoropolymer and (b) a layer of polyethylene terephthalate having at least two planar directions; and (2) an encapsulant portion including a polyolefin, a silane, one or more cross-linking agents, and a plasticizer. In some embodiments, the outer layer of the integrated film has a tensile modulus of less than 100,000 psi. In some embodiments, the polyethylene terephthalate layer has a shrinkage of less than 1% in each of two planar directions when held for 15 minutes at 150° C measured in accordance with ASTM 2305-02. In some embodiments, the integrated film further includes a second outer layer of an olefinic polymer of the formula CH₂=CHR", wherein R" is hydrogen or a Cns alkyl.

In some exemplary embodiments, a multilayer, integrated film capable of use in a solar module, comprises a backsheet portion including at least two of the following three layers: (1) a layer of a fluoropolymer; (2) a layer including a polyester; and (3) a layer including an olefinic polymer of the formula CH₂=CHR", wherein R" is hydrogen or a C_n8 alkyl; and an encapsulant portion including a polyolefin, a silane, one or more cross-linking agents, and a plasticizer. In some embodiments, the fluoropolymer is semi-crystalline.

In some exemplary embodiments, a multilayer, integrated film capable of use in a solar module includes a backsheet portion including at least two of the following three layers: (1) a layer including a fluoropolymer; (2) a layer including a polyester; and (3) a layer including a polyamide; and an encapsulant portion including a polyolefin, a silane, one or more cross-linking agents, and a plasticizer.

In some embodiments, an integrated film as described herein further includes an olefinic layer.

Another exemplary embodiment of the present disclosure is a solar module including one or more solar cells; and a multilayer integrated film as described herein.

Another exemplary embodiment of the present disclosure is a method of making a multilayer integrated film, comprising: coextruding the backsheet portion and the encapsulant portion to form a multi-layered film as described herein; and cross-linking the coextrusion.

In some exemplary embodiments, the multilayer integrated film further includes a top layer including cross-linked polyethene homopolymers or copolymers, and wherein the cross-linked polyethene homo olymers or copolymers are selected from a group consisting essentially of (a) polyethene copolymers comprising more than 99% by mole of repeating units derived from ethene and (b) polyethene copolymers comprising at least 50% by mole of repeating units derived from ethene and further including one or more alkene comonomers.

In some exemplary embodiments of the multilayer integrated film, the first outer

layer comprises interpolymerized units of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride. In some exemplary embodiments of the multilayer integrated film, the first outer layer comprises interpolymerized units of tetrafluoroethylene and ethylene. In some exemplary

embodiments, the multilayer integrated film further includes a tie layer between at least one of the first outer layer and the intermediate layer and the second outer layer and intermediate layer. In some exemplary embodiments of the multilayer integrated film, the second outer layer comprises interpolymerized units of ethylene vinyl actetate. In some exemplary embodiments of the multilayer integrated film, the thickness of the second outer layer is greater than or about twice the combined thickness of the first outer layer and the intermediate layer. In some exemplary embodiments of the multilayer integrated film, the thickness of the backsheet portion is greater than 15 mils. In some exemplary embodiments of the multilayer integrated film, the fluoropolymer has a tensile modulus of less than 80,000 psi. In some exemplary embodiments of the multilayer integrated film, the shrinkage of the backsheet portion is less than 1% at 150°C when held for 15 minutes measured in accordance with ASTM 2305-02. In some exemplary embodiments of the multilayer integrated film, the backsheet portion and the encapsulant portion are coextruded. In some exemplary embodiments, the multilayer integrated film further includes at least one of flame retardants and anti-dripping agents. In some exemplary embodiments of the multilayer integrated film, the backsheet portion and the encapsulant portion are bonded together.

In some exemplary embodiments, the multi- layered film has a thickness of between about 0.25 mm and about 1.0 mm. In some exemplary embodiments, the back layer contains no pigments. In some exemplary embodiments, the back layer contains carbon particles. In some exemplary embodiments, the multi-layered film has at least one of (a) a reduction of dielectric breakdown voltage of less than 1% and (b) a reduction in elongation at break and tensile strength of less than 20% after being exposed to steam at a temperature of 121 °C and a pressure of 1 bar for 100 hours. In some exemplary embodiments, at least two of the layers of the multi-layered film are coextruded. In some exemplary embodiments, the back layer and the back layer are bonded together.

In some exemplary embodiments, the plasticizer in the encapsulant layer is non-polar. In some exemplary embodiments, the plasticizer in the encapsulant layer is selected from a group consisting essentially of ethylene/a-olefin copolymers and C4-C10 polyolefin homopolymers. In some exemplary embodiments, the plasticizer in the encapsulant layer has a Tg<-50°C. In some exemplary embodiments, the plasticizer in the encapsulant layer has a Tg<-70°C. In some exemplary embodiments, the plasticizer in the encapsulant layer is liquid at 20°C. In some exemplary embodiments, the polyolefm in the encapsulant layer is an ethylene/a-olefin copolymer. In some exemplary embodiments, the a-olefin moiety of the ethylene/a-olefin copolymer includes four or more carbons. In some exemplary embodiments, the ethylene/a-olefin copolymer is a low crystalline ethylene/a-olefin copolymer. In some exemplary embodiments, the low crystalline ethylene/a-olefin copolymer has a DSC peak melting point of less than or equal to 50°C. In some exemplary embodiments, the low crystalline ethylene/a-olefin copolymer is a butene a-olefin. In some exemplary embodiments, the encapsulant layer includes greater than 70% by weight of low crystalline ethylene/a-olefin copolymer. In some exemplary embodiments, the silane in the encapsulant layer is an unsaturated alkoxysilane. In some exemplary embodiments, the unsaturated alkoxysilane is an acrylic alkoxysilane. In some exemplary embodiments, the one or more cross-linking agents in the encapsulant layer are one of a thermal curative and a photo-curative. In some exemplary

embodiments, the thermal curative is a peroxide. In some exemplary embodiments, the encapsulant layer further includes a coagent. In some exemplary embodiments, the encapsulant layer further includes an additional resin. In some exemplary embodiments, the additional resin is an additional low crystalline ethylene/a-olefin copolymer. In some exemplary embodiments, the additional resin is one of an ethylene/butene copolymer and an ethylene/octene copolymer. In some exemplary embodiments, the encapsulant layer includes multiple layers.

Brief Description of the Drawings

The present disclosure may be more completely understood in consideration of the following detailed description of various embodiments of the disclosure in connection with the accompanying drawings, in which:

Fig. 1 is a cross-sectional schematic view of one type of prior art photovoltaic solar module. Fig. 2 is a cross-sectional schematic view of one type of prior art photovoltaic solar module. Fig. 3 is a cross-sectional schematic view of one type of prior art photovoltaic solar module. Fig. 4 is a cross-sectional schematic view of one embodiment of an integrated multilayer film.

The figures are not necessarily to scale. It will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number. Detailed Description

In the following detailed description, reference may be made to the accompanying set of drawings that form a part hereof and in which are shown by way of illustration several specific embodiments. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense.

The present application generally relates to films capable of use in solar modules. The films of the present disclosure can be used in any type of photovoltaic solar module, including, for example, any of the solar modules described in the background. In one exemplary embodiment, a multilayer integrated film capable of use in a photovoltaic solar module includes a backsheet portion and an encapsulant portion.

The integrated films described herein have a multi-layered structure. As shown in Fig. 4, when viewed from top (referred to herein as the side of the integrated film that is adjacent to (e.g., bonded to) the solar module) one exemplary integrated film 200 includes the following layers: an encapsulant layer 210 and a back layer 240. All other layers are optional. For example, top layer 220 need not be included in all embodiments. There may or there may not be other layers between some or all of these layers. In some embodiments, the back and encapsulant layer / portions are bonded directly to each other. In some embodiments, an adhesion promoting layers is between the back and encapsulant portions/layers.

The combination of the layers may have a thickness effective to provide the electrical breakdown voltage of at least 10 kV or at least 20 kV and / or some or all of the mechanical properties as described herein. In some embodiments, the integrated film has a thickness of between about 0.25 mm and about 1.0 mm. In some embodiments, the integrated film has a thickness of between about 0.35 mm and about 1.0 mm. In some embodiments, the integrated film has a thickness of between about 0.5 mm and about 0.8 mm.

The individual portions / layers of the multilayer integrated film will now be described in greater detail.

Backsheet Portion

The main purpose of the backsheet layer/portion is to protect the solar cell(s) from

mechanical degradation and from the environment. Typically, the backsheet portion/ layer has a thickness between about 50 μηι and about 100 μηι. In some embodiments, the backsheet

portion/layer includes one or more of carbon particles and/or pigments (e.g., white pigments). In some embodiments, the back layer is black in colour due the presence of substantial amounts of carbon particles. However, the layer can be of a different colour if pigments or paints are used. The carbon particles may be modified, for example surface treated, coated or may contain functionalised groups (e.g., by chemical reaction with chemical modifiers or by adsorption of chemicals). Carbon particles include graphite, fullerenes, nanotubes, soot, carbon blacks (e.g., carbon black, acetylene black, ketjen black). Typically, the backsheet portion/layer may contain from about 1% to about 6% or up to about 10% weight based on the weight of the layer of carbon particles. The loading with carbon particles may be increased but in that case the layer may become electron conductive. In this case the layer can be earthed when it is incorporated into a solar module.

In some embodiments, the backsheet portion/layer includes one or more of antioxidants, UV- absorbers, cross-linkers, flame retardants, photoluminescent additives, and/or anti dripping agents.

The amount of these ingredients may be individually or combined be from about 1% wt to 40% wt. It has been found that the film is resistant enough to only show little yellowing upon extensive heat, dampness, or UV treatment. In some embodiments, the backsheet portion/layer includes up to 35% or up to 30% or up to 20% or up to 10% by weight of flame retardant based on the weight of the layer and has a dielectric break down voltage of at least 20 kV. The inclusion of flame retardants or anti- dripping agents may results in a film having good anti-burning behaviour while maintaining the desired mechanical, electrical, heat, and moisture properties described herein.

The backsheet portion/layer may be in direct contact with the encapsulant portion/ layer or may be separated from it by one or more intermediate layers. In some embodiments, the backsheet portion/ layer forms a continuous interface with the encapsulant portion/ layer such that no tie layer, primer, or adhesive is between the two layers.

In some embodiments, the backsheet portion/layer includes at least two of a first outer layer, an intermediate layer, and an outer layer, each of which will be described in detail below. In some embodiments, the backsheet portion/layer includes a first outer layer, an intermediate layer, and an outer layer. Generally, the first outer layer is a semi-crystalline fluoropolymer. In some

embodiments, the first outer layer has a tensile modulus of less than 100,000 psi, as defined in ASTM D638. In some embodiments, the intermediate layer includes a polyester. In some embodiments, the intermediate layer has a shrinkage rate of less than 1% measured at 150° C when held for about 15 minutes. In some embodiments, the second outer layer is an olefinic polymer. In some embodiments, these layers are bonded together in the noted order to provide the multilayer film.

First Outer Layer:

The fluoropolymer component of the first outer layer can be selected from a variety of fluoropolymers. Such fluoropolymers are typically copolymers of TFE or VDF or

(chlorotrifluoroethylene) CTFE with other fluorinated or non-fluorinated monomers. Representative materials include copolymers of tetrafluoroethylene-ethylene (ETFE), tetrafluoroethylene- hexafluoropropylene (FEP), tetrafluoroethylene-perfluoroalkoxyvinlyether (PFA), copolymers of vinylidene fluoride and chlorotrifluoroethylene, tetrafluoroethylene-hexafluoropropylene-ethylene (HTE), polyvinyl fluoride (PVF), copolymers of vinylidene fluoride and chlorotrifluoroethylene, or a copolymer derived from tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and vinylidene fluoride (VDF), such as the THV series available from Dyneon LLC, Oakdale, Minnesota.

In some embodiments, the first outer layer possesses a tensile modulus of less than 100,000 psi. The noted tensile modulus is directed to achieving desired flexural characteristics in order to make the finished film structure pliable in its intended application. Additionally, the fluoropolymer outer layer is preferably capable of providing low permeability characteristics to the construction in order to protect internal components of the file or of the preferred solar cell application.

A preferred class of fluorinated copolymers suitable as the first outer layer are those having interpolymerized units derived from tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride, and optionally a perfluoro alkyl or alkoxy vinyl ether. Preferably these polymers have less than about 30 weight percent (wt%) VDF, more preferably between about 10 and about 25 wt%, of its interpolymerized units derived from VDF. A non-limiting example includes THV 500 available from Dyneon LLC, Oakdale, Minnesota.

Another preferred class of materials suitable for use as the first outer layer include various combinations of interpolymerized units of TFE and ethylene along with other additional monomers such as HFP, perfluoro alkyl or alkoxy vinyl ethers (PAVE or PAOVE). An example is HTE 1510, available from Dyneon LLC, Oakdale, Minnesota.

In some embodiments, the first outer layer is the only outer layer.

The Intermediate Layer

Any polyester polymer capable of being processed into film form may be suitable as an intermediate layer. These may include, but are not limited to, homopolymers and copolymers from the following families: polyesters, such as polyethylene terephthalate (PET), and liquid crystalline polyesters.

In some embodiments, the intermediate layer is not positioned between other layers; it can be the outer or the inner layer.

In an alternative embodiment, the intermediate layer may include other polymers such, for example: polyarylates; polyamides, such as polyamide 6, polyamide 1 1, polyamide 12, polyamide 46, polyamide 66, polyamide 69, polyamide 610, and polyamide 612; aromatic polyamides and polyphthalamides; thermoplastic polyimides; polyetherimides; polycarbonates, such as the polycarbonate of bisphenol A; acrylic and methacrylic polymers such as polymethyl methacrylate; chlorinated polymers, such as polyvinyl chloride and polyvinylidene chloride; polyketones, such as poly(aryl ether ether ketone) (PEEK) and the alternating copolymers of ethylene or propylene with carbon monoxide; polystyrenes of any tacticity, and ring- or chain-substituted polystyrenes;

polyethers, such as polyphenylene oxide, poly(dimethylphenylene oxide), polyethylene oxide and polyoxymethylene; cellulosics, such as the cellulose acetates; and sulfur-containing polymers such as polyphenylene sulfide, polysulfones, and polyethersulfones. A most preferred material is

polyethyleneterepthalate, (PET).

In some embodiments, the intermediate layer is pre-shrunk prior to formation of the multilayer backsheet portion/layer. The shrinking of the polyester intermediate layer results in an intermediate layer that will shrink less than 1% of its total length in either planer direction when exposed to a temperature of 150°C during a period of 15 minutes, in accordance with ASTM D 2305- 02. Such films are commercially available or can be prepared by exposing the film, under minimal tension, to a temperature above its glass transition temperature, preferable above 150°C for a period of time sufficient to pre-shrink the film. Such thermal treatment can occur either as a post treatment or during the initial manufacturing process used to produce the film.

The Second Outer Layer

For purposes of clarity, not all embodiments include a second outer layer; the second outer layer is optional.

Olefinic polymers may be used in the second or first outer layer. Some exemplary olefinic polymers include, for example, polymers and copolymers derived from one or more olefinic monomers of the general formula CH₂=CHR", wherein R" is hydrogen or Ci_i₈ alkyl. Examples of such olefinic monomers include propylene, ethylene, and 1 -butene, with ethylene being generally preferred. Representative examples of polyolefins derived from such olefinic monomers include polyethylene, polypropylene, polybutene- 1 , poly(3-methylbutene), poly(4-methylpentene) and copolymers of ethylene with propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 4-methyl-l-pentene, and 1 -octadecene.

The olefinic polymers may optionally comprise a copolymer derived from an olefinic monomer and one or more further comonomers that are copolymerizable with the olefinic monomer. These comonomers can be present in the polyolefin in an amount in the range from about 1 to 10 wt- % based on the total weight of the polyolefin. Useful such comonomers include, for example, vinyl ester monomers such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl chloroacetate, vinyl chloropropionate; acrylic and alpha-alkyl acrylic acid monomers, and their alkyl esters, amides, and nitriles such as acrylic acid, methacrylic acid, ethacrylic acid, methyl acrylate, ethyl acrylate, Ν,Ν-dimethyl acrylamide, methacrylamide, acrylonitrile; vinyl aryl monomers such as styrene, o-methoxystyrene, p-methoxystyrene, and vinyl naphthalene; vinyl and vinylidene halide monomers such as vinyl chloride, vinylidene chloride, and vinylidene bromide; alkyl ester monomers of maleic and fumaric acid such as dimethyl maleate, and diethyl maleate; vinyl alkyl ether monomers such as vinyl methyl ether, vinyl ethyl ether, vinyl isobutyl ether, and 2-chloroethyl vinyl ether; vinyl pyridine monomers; N-vinyl carbazole monomers, and N-vinyl pyrrolidine monomers.

Optionally, the second outer layer may be cross-linked. Any cross-linking method can be used, including, for example, chemical or e-beam cross-linking.

The olefinic polymers may also contain a metallic salt form of a polyolefin, or a blend thereof, which contains free carboxylic acid groups. Illustrative of the metals which can be used to provide the salts of said carboxylic acid polymers are the one, two and three valence metals such as sodium, lithium, potassium, calcium, magnesium, aluminum, barium, zinc, zirconium, beryllium, iron, nickel and cobalt.

The olefinic polymers may also include blends of these polyolefins with other polyolefins, or multi-layered structures of two or more of the same or different polyolefins. In addition, they may contain conventional adjuvants such as antioxidants, light stabilizers, acid neutralizers, fillers, antiblocking agents, pigments, primers and other adhesion promoting agents.

Preferred olefinic polymers include homopolymers and copolymers of ethylene with alpha- olefins as well as copolymers of ethylene and vinyl acetate. Representative materials of the latter include Elvax™ 150, 3170, 650 and 750 available from E.I. du Pont de Nemours and Company.

Optionally, one or more layers in the backsheet portion/layer may also include known adjuvants such as antioxidants, light stabilizers, conductive materials, carbon black, graphite, fillers, lubricants, pigments, plasticizers, processing aids, stabilizers, and the like including combinations of such materials. In addition, metallized coatings and reinforcing materials also may be used in the backsheet portion. These include, e.g., polymeric or fiberglass scrim that can be bonded, woven or non-woven. Such a material optionally may be used as a separate layer or included within a layer in a multi-layer embodiment.

In some embodiments, it is preferred that the multilayer articles of the backsheet portion do not significantly delaminate during use. That is, the adhesive bond strength between the different layers of the multi-layer article should be sufficiently strong and stable so as to prevent the different layers from separating on exposure to, for example, moisture, heat, cold, wind, chemicals and or other environmental exposure. The adhesion may be required between non-fluoropolymer layers or adjacent the fluoropolymer layer. Various methods of increasing interlayer adhesion in all cases are generally known by those of skill in the art. The backsheet portion may also include a bonding interface or agent between said outer and intermediate layers. A variety of methods have been employed to bond polymeric materials comprising a fluoropolymer to substantially non-fluorinated polymeric materials. For example, the layers can be adhesively bonded together by a layer of adhesive material between the two layers. Alternatively, surface treatment of one or both of the layers, used independently or in conjunction with adhesive materials, has been used to bond the two types of materials together. For example, layers comprising a fluoropolymer have been treated with a charged gaseous atmosphere followed by lamination with a layer of a non-fluorinated polymer. As another approach, "tie-layers" have been used to bond a fluoropolymer material to a layer of material comprising a substantially non-fluorinated polymer.

One specific surface treatment of a fluoropolymer for improving adhesion is disclosed in U.S. Pat. No. 6,630,047, incorporated herein by reference in its entirety. The specific surface treatment involves the use of actinic radiation, such as ultraviolet radiation in combination with a light- absorbing compound and an electron donor.

In a preferred embodiment, one such tie layer method for improving interlayer adhesion with the fluoropolymer comprises blending a base and an aromatic material such as a catechol novolak resin, a catechol cresol novolak resin, a polyhydroxy aromatic resin (optionally with a phase transfer catalyst) with the fluoropolymer and then applying to either layer prior to bonding. Alternatively, this composition may be used as the fluoropolymer layer without separate tie layer as disclosed in U.S. Published Application No. 2005/0080210 Al, herein incorporated by reference in its entirety.

Another tie layer method for bonding fluoropolymers is the use of a combination of a base, a crown ether and a non- fluoropolymer. This method is disclosed in U.S. Pat. No. 6,767,948, incorporated herein by reference in its entirety.

Another method that may be used as a tie layer or as a primer for bonding fluoropolymers involves the use of an amino substituted organosilane. The method is fully disclosed in U.S. Pat. No. 6,753,087, incorporated herein by reference in its entirety. The organosilane may optionally be blended with a functionalized polymer.

Adhesion between non- fluoropolymer layers may also be accomplished in a variety of ways including the application of anhydride or acid modified polyolefins, the application of silane primers, utilization of electron beam radiation, utilization of ultraviolet light and heat, or combinations thereof.

In a preferred embodiment, the intermediate layer and the second outer layer may be combined such as those commercially available as 3M™ Scotchpak™ Heat Sealable Polyester Films which include PET films combined with olefmic polymers such as polyester and ethylene vinyl acetate.

Those of ordinary skill in the art are capable of matching the appropriate the conventional bonding techniques to the selected multilayer materials to achieve the desired level of interlayer adhesion. The multi-layer backsheet portion can be prepared by several different methods. For instance, one process for preparing the backsheet portion involves extruding one layer through a die to form a length of film. A second extruder supplies a die to coat another layer of molten polymer onto a surface of the first film. Additional layers can be added through similar means. Alternatively, the polymeric resins of two or more substituent layers may be co-extruded through a multi-manifold die to yield an intermediate or final product.

Those skilled in the art of coating technology are capable of selecting process equipment and processing conditions to address selected materials and thereby produce the desired multilayer film.

Following the extrusion operations, the multi-layer article may be cooled, e.g., by immersion in a cooling bath. This process can be used to form one or more multilayer backsheet portions. In addition, the layers are preferably pressed together, such as through a nip or platen or other known means. Generally, increasing the time, temperature, and/or pressure can improve interlayer adhesion. The conditions for bonding any two layers can be optimized through routine experimentation.

Yet another useful method is to pre-form the individual film layers and then contact them in a process such as thermal lamination in order to form a finished backsheet portion.

The inter-layer adhesion promoting agents, if required, can be applied either sequentially, simultaneously or in-situ with any of the before described processes.

The intermediate layer, prior to application of the outer layers, should have a shrinkage rate of less than 1% at 150°C when held for about 15 minutes, as previously indicated. In that regard, it may be necessary to pre-shrink the intermediate layer before the application of the other outer layers. Even then so, care must be taken with the addition of the outer layers such that inner layer is not overly tensioned or strained which can reintroduce shrinkage into the overall construction. Pre-shrinking of the film after the addition of other layers can become exceedingly difficult especially if one or more of the additional outer layers has a softening or melting point that is within the temperature range required to pre-shrink the intermediate layer.

The thickness of the individual layers within the backsheet portion can be varied and tailored per the end-use application requirements. In general, the outer layer of the backsheet portion will be from about 0.5 mils to 5 mils, preferably 1 to 2 mils thick; the intermediate layer will be from about 1 to 10 mils, preferable 2 to 4 mils; and the outer polyolefin layer will be from 1 to 20 mils or greater, preferable it is 10 mils or greater. The thickness of the overall backsheet construction is typically 15 mils or greater, and in a preferred embodiment, the thickness of the outer polyolefin layer is as thick, preferably twice as thick, or greater than the combined thickness of the intermediate and

fluoropolymer layers. Encapsulant Portion / Layer

Polyolefin

In some embodiments, the polyolefin is one or more of EVA, high density polyethylene, ionomers, polystyrene, and poly vinyl butarate.

In some embodiments, the polyolefin is an ethylene/a-olefin copolymer. As used herein, the term "ethylene/a-olefin copolymer" refers to polymers comprising a class of hydrocarbons manufactured by the catalytic oligomerization (i.e., polymerization to low-molecular- weight products) of ethylene and linear a-olefin monomers. The ethylene/a-olefin copolymers may be made, for example, with a single site catalyst such as a metallocene catalyst or multi-site catalysts such as Ziegler-Natta and Phillips catalysts. The linear a-olefin monomers typically are 1-butene or 1-octene but may range from C3 to C20 linear, branched or cyclic a-olefin. The a-olefin may be branched but only if the branch is at least alpha to the double bond, such as 3 -methyl- 1-pentene. Examples of C3- C20 a-olefins include propylene, 1 -butene, 4-methyl- 1 -butene, 1 -hexene, 1 -octene, 1 -dodecene, 1 - tetradecene, 1 -hexadecene and 1 -octadecene. The α-olefins can also contain a cyclic structure such as cyclohexane or cyclopentane, resulting in an α-olefin such as 3-cyclohexyl-l propene (allyl cyclohexane) and vinyl cyclohexane. Although not α-olefins in the classical sense of the term, for purposes of this disclosure certain cyclic olefins, such as norbornene and related olefins, are a-olefins and can be used. Similarly, styrene and its related olefins (for example, a-methyl styrene) are a- olefins for the purposes of this disclosure. Acrylic and methacrylic acid and their respective ionomers, and acrylates and methacrylates, however are not α-olefins for the purposes of this disclosure. Illustrative ethylene/a-olefin copolymers include ethylene/1 -butene, ethylene/ 1-octene, ethylene/1 -butene/ 1-octene, ethylene/styrene. The polymers can be block or random. Exemplary commercially available low crystalline ethylene/a-olefin copolymers include resins sold under the tradenames "ENGAGE" ethylene/ 1-butene and ethylene/ 1-octene copolymers and "FLEXOMER" ethylene/ 1 -hexene copolymer, available from Dow Chemical Co., and homogeneously branched, substantially linear ethylene/ α-olefin copolymers such as "TAFMER", available from Mitsui Petrochemicals Company Limited, and "EXACT", available from ExxonMobil Corp. As used herein, the term "copolymer" refers to polymers made from at least 2 monomers.

In some of these embodiments, the α-olefin moiety of the ethylene/a-olefin copolymer includes four or more carbons. In some embodiments, the ethylene/a-olefin copolymer is a low crystalline ethylene/a-olefin copolymer. As used herein, the term "low crystalline" means crystallinity (according to method disclosed in ASTM F2625-07) of less than 50% by weight. In some embodiments, the low crystalline ethylene/a-olefin copolymer is a butene a-olefin. In some embodiments the a-olefin of the low crystalline ethylene/a-olefin copolymer has 4 or more carbons. In some embodiments, the low crystalline ethylene/a-olefin copolymer has a DSC peak melting point of less than or equal to 50°C. As used herein, the term "DSC peak melting point" means a melting point determined by DSC (107min) under nitrogen purge as the peak with the largest area under the DSC curve.

In some embodiments, the film is greater than 35% by weight low crystalline ethylene/a- olefin copolymer. In some embodiments, the film is greater than 50% by weight low crystalline ethylene/a-olefin copolymer. In some embodiments, the film is greater than 70% by weight low crystalline ethylene/a-olefin copolymer.

In some embodiments, the film includes additional polyolefin resins. Exemplary additional resins include, for example, low crystalline ethylene/a-olefin copolymer, HDPE, and polystyrene. In embodiments where the additional resin is a low crystalline ethylene/a-olefin copolymer, the two copolymers could, for example, have respective DSC peak melting points of, for example, less than 50° C and greater than 50° C. In alternative exemplary embodiments, one low crystalline ethylene/a- olefin copolymer could have a DSC peak melting point of less than 50° C while the other low crystalline ethylene/a-olefin copolymer could have a DSC peak melting point of greater than 55° C, or greater than 60° C, or greater than 65° C, or greater than 70° C, or greater than 75° C. In another exemplary embodiment one low crystalline ethylene/a-olefin copolymer could have a DSC peak melting point of greater than 50° C while the other low crystalline ethylene/a-olefin copolymer could have a DSC peak melting point of less than 45° C, or less than 40° C, or less than 35° C. In an alternative exemplary embodiment, one of the two low crystalline ethylene/a-olefin copolymers is ethylene/butene copolymer and the other is an ethylene/octene copolymer.

Silane

Exemplary silanes for use in the films of the present disclosure include, for example, silanes that include an ethylenically unsaturated hydrocarbyl group (such as, for example, vinyl, allyl, isopropenyl, butenyl, cyclohexenyl or y-(meth)acryloxy allyl group) and a hydrolysable group (such as, for example, methoxy, ethoxy, formyloxy, acetoxy, propionyloxy, alkyl, arylamino,

hydrocarbonyloxy or hydrocarbylamino groups). In some exemplary embodiments, the silane is an unsaturated alkoxysilane. In some exemplary embodiments, the unsaturated alkoxysilane is an acrylic silane. Some examples include vinyl trimethoxysilane, vinyl triethoxysilane, and 3- (meth)acryloxypropyl trimethoxysilane. Commercially available examples include "SILQUEST A 174 and SILQUEST A171".

The amount of silane is typically at least about 0.05%, for example 0.1%, for example 0.5%, for example 1.0%, for example 2.0%, for example 10.0%, or even for example 10.0%. Cross-Linking Agents

The films of the present disclosure include one or more cross-linking agents. Exemplary cross-linking agents include, for example, thermal and photo cross-linking agents.

Some exemplary thermal cross-linking agents include, for example, peroxides. Some exemplary peroxides include, for example, diacyl peroxides (such as, for example, dilauryl peroxide and didecanoyl peroxide), alkyl peresters (such as, for example, tert-butyl peroxy-2-ethylhexanoate), perketals (such as, for example, l,l-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane or l,l-di(tert- butylperoxy)cyclohexane), dialkyl peroxides (such as, for example, tert-butyl cumyl peroxide, di(tert- butyl) peroxide and dicumyl peroxide), C-radical donors (such as, for example, 3,4-dimethyl-3,4- diphenylhexane and 2,3-dimethyl-2,3-diphenylbutane), and azo compounds (such as, for example, 2,2'-azodi (2-acetoxypropane)). Additional exemplary azo compounds include those described in U.S. Patent Nos. 3,862,107 and 4, 129,531. Some exemplary commercially available peroxides include, for example, "LUPEROX TBEC", "LUPEROX 231 ", and "LUPEROX P. Mixtures of two or more cross-linking agents may be used.

The amount of cross-linking agent varies, but the minimum amount is that sufficient to afford the desired range of crosslinking. In some embodiments, the film includes at least about 0.05%. In some embodiments, the film includes at least about 0.5%. In some embodiments, the film includes at least about 1.0%. In some embodiments, the film includes at least about 2.0%. In some

embodiments, the film includes at least about 5.0%.

Plasticizer(s)

Preferred plasticizers for use in the films described herein are those that are non- fugitive and/or crosslink into the polymers in the film. Plasticizers used in the films described herein may improve extrusion processing speed and reduce film shrinkage while increasing storage modulus (creep resistance) at temperatures between about 100° C and 200° C. Preferably, such plasticizers also are not substantially tacky at normal handling or storage temperatures. In some exemplary embodiments, the plasticizer(s) used in the films are liquids at 20°C. In some exemplary

embodiments, the plasticizer does not act as a tackifier.

In some exemplary embodiments, the plasticizer is non-polar. As used herein, the term "nonpolar plasticizer" means a nonpolar additive that increases the plasticity, fluidity or flowability of a low crystalline ethylene/a-olefin polymer and has a MW of less than 10,000 as determined by ASTM D6474. As used herein, nonpolar plasticizers do not include, for example, common polar polyvinylchloride (PVC) plasticizers such as phthalic acid diesters (e.g., diethylphthlate, dibutylphthlate, dioctylphthlate) or other polar ester plasticizers such as trimellitates, adipates, sebacates, maleates, citrates or benzoates. Examples of non-polar plasticizers include, for example, ethylene/a- olefin copolymers and C4-C10 polyolefin homopolymers. In some exemplary embodiments, the nonpolar plasticizer may be selected from the group consisting of ethylene/a-olefin copolymers and C4-C 10 polyolefin homopolymers.

Exemplary commercially available nonpolar plasticizers include those under the tradename "SPECTRASYN" commercially available from ExxonMobil Chemical, Baton Rouge, LA,

"KAYDOL" white mineral oil commercially available from Sonneborn Refined Products B.V., Amsterdam, the Netherlands, "INDOPOL" polybutenes commercially available from Ineos

Oligomers, League City, TX. and "TRILENE" ethylene propylene (EP) or EPDM copolymers commercially available from Lion Copolymer, Baton Rouge, LA.

The nonpolar plasticizer may have a Tg of less than -50°C, for example less than -55°C, for example less than -65°C, for example less than -70°C, or even for example less than -75°C. The plasticizer may have a DSC peak melting point of less than 80°C, for example less than 60°C, for example less than 40°C or even for example less than 20°C. In one embodiment the plasticizer is a liquid at 20°C.

In some exemplary embodiments, conventional plasticizers such as are commonly used for polyf vinyl chloride) are substantially absent. As used in this paragraph, the term "substantially absent," means that these compounds are not a dded deliberately to the compositions and - if present - comprise less than Q.5wt % of the total film composition.

In particular, plasticizers such as ph alates, adipates, trimeJlitate esters, polyesters, and other functionalized plasticizers as disclosed in, for example, US 3,318,835; US 4,409,345; WO 02/31044 Al; and PLASTICS ADDITIVES 499-504 (Geoffrey Pritchard, ed., Chapman & Hall 1998) are substantially absent.

The amount of plasticizer is typically at least about 0.5%. In some embodiments, the amount of plasticizer is at least about 1.0%. In some embodiments, the amount of plasticizer is at least about 2.0%. In some embodiments, the amount of plasticizer is at least about 5.0%. In some embodiments, the amount of plasticizer is at least about 10.0%. In some embodiments, the amount of plasticizer is at least about 20.0%.

Additives

In some exemplary embodiments, the films of the present disclosure include a coagent. Exemplary coagents include, for example, free radical crosslinking coagents (promoters or co- initiators). Examples of such coagents include multifunctional vinyl monomers and polymers, triallyl isocyanuarate, trimethylolpropane tnmethylacrylate, divinyl benzene, acrylates and methacrylates of polyols, allyl alcohol derivatives, and low molecular weight polybutadiene. Sulfur crosslinking promoters include benzothiazyl disulfide, 2-mercaptobenothiazole and tetramethylthiuram

tetrasulfide.

In some exemplary embodiments, the film further includes one or more UV absorbers. UV absorbers absorb light and can thereby protect polymeric materials and/or solar cells. Some exemplary UV absorbers include, for example, triazines, benzotriazoles, hydroxybenzophenones, hydroxyphenyltriazines, esters of benzoic acids, and mixtures of two or more thereof. In some exemplary embodiments, the films of the present disclosure include 0.01% UV absorber. In some exemplary embodiments, the films of the present disclosure include 0.1% UV absorber. In some exemplary embodiments, the films of the present disclosure include 0.5% UV absorber. In some exemplary embodiments, the films of the present disclosure include 1% UV absorber.

Films including UV absorbers have "UV cutoffs." As used herein, the term "UV cutoff refers to the wavelength transmission of a film and means that the film will block substantially all UV light below the specified wavelength threshold. In some embodiments, the films of the present disclosure have a "UV cutoff of 310, 350, and 380 nm, respectively. Such films can, for example, include less than 0.5% of "TINUVIN 622" HALS, "CHIMASSORB 81" UV absorber, or "TINUVIN 460" UV absorber, respectively.

In some exemplary embodiments, the film includes one or more hindered amine light stabilizer ("HALS"). HALS are light stabilizers rather than absorbers and scavenges radicals by production of nitroxyl radicals. In some embodiments, inclusion of a HALS instead of a UV absorber may permit entry of more light energy into a solar cell. Some exemplary HALS include, for example, cyclic amines, secondary, tertiary, acetylated, N-hydrocarbyloxy substituted, hydroxy substituted N- hydrocarbyloxy substituted, or other substituted cyclic amines which are further characterized by a degree of steric hindrance, generally as a result of substitution of an aliphatic group or groups on the carbon atoms adjacent to the amine function.

In some exemplary embodiments, the films of the present disclosure include 0.01% HALS. In some exemplary embodiments, the films of the present disclosure include 0.1% HALS. In some exemplary embodiments, the films of the present disclosure include 0.5% HALS. In some exemplary embodiments, the films of the present disclosure include 1% HALS.

Other additives include, for example, pigments such as carbon black and titanium dioxide; inorganic fillers such as talc, fumed silica, precipitated silica, barium sulfate and calcium carbonate; crosslinkers; anti-oxidants; scorch inhibitors; flame retardants; and catalysts for crosslinking such as organo tin compounds, for example di-n-butyl tin dilaurate. Other suitable catalysts include, for example titanium compounds and metal alkoxides, for example aluminum isopropoxide and zirconium isopropoxide. In some embodiments, the encapsulant films include multiple layers. In one exemplary implementation, an encapsulant film of the present disclosure includes three or more layers. In one exemplary implementation of this, the cross-linking agent(s), silane, and/or polyolefin are in different layers. For example, the cross-linking agent(s) could be substantially or entirely in a center layer and the polyolefin and silane could be in the outer layers.

The encapsulant films and materials of the present disclosure perform at least some of the following advantages over currently available encapsulant films: minimization of the incidence of creep, shrinkage, yellowing, corrosion, and delamination while maintaining or improving light transmission, film processability, and manufacturing cost.

Optional Layers

Some embodiments of the integrated film include one or more top layers positioned between the encapsulant layer and the backsheet or back layer. A top layer may, for example, introduce a colour or a coloured pattern representing information or decoration into the solar module. Such colour or pattern can be introduced by printing it onto the top layer or by using a top layer containing pigments or a combination of pigments. In some embodiments, the top layer contains white pigments and/or reflective particles. The presence of a top layer may increase the efficiency of the solar module by reflecting light and may also or alternatively protect the back layer from degradation by preventing or hindering light and/or UV irradiation to be incident on the back layer. In some embodiments, the top layer is the same or a similar composition as the back layer. In some embodiments, the top layer includes one or more of UV-stabilizers, antioxidants, cross-linking agents, flame retardants, and anti-dripping agents. In some embodiments, the top layer has a thickness between about 10 μηι and about 150 μηι. In some embodiments, the top layer has a thickness between about 50 μηι and about 100 μηι. In some embodiments, the top layer includes one or more of a cross-linked PE polymer, a non-cross-linked PE polymer, a cross-linked PP polymer, and a non- cross-linked PP polymer. In some embodiments, the top layer is free of ionomers or acid copolymers.

In some embodiments, the multilayered integrated film includes one or more metal layers (e.g., a metal foil may be incorporated). In some embodiments, a metal foil is positioned on the backside of the back layer. In such embodiments, the metal foil can be covered by one or more additional layers (e.g., a polyolefinic layer containing polyolefins to protect the metal film from deterioration by weather and environment). The thickness of this optional metal layer may be in the range of 5 - 100 μηι based on the type of material used.

Some embodiments include one or more external protection layers. The external protection layer(s) are adjacent to the backside of the integrated film such that it is exposed to the environment from the non- light-receiving side of the solar module. Where present, this layer can include, for example, polyolefms, polyurethanes, polyarylates, silicones, fluoropolymers, and combinations thereof; additives that increase the film's UV stability, thermal stability, and/or resistance to oxidation or corrosion; flame retardants; anti-scratch materials; or easy-to-clean materials. It may also be a coloured layer to provide the outside of the integrated film with a color other than black.

Some embodiments include one or more scrim or net layers that may increase dimensional stability and handling properties. Scrim or net type layers may also improve the anti dripping performance during burning. Scrim or net layers may be, for example, net-shaped or non- woven layers of a polymeric or plastic material or organic or inorganic fibers. The Multi-Layered Integrated Film

A particular advantage of at least some embodiments of the multi-layered integrated films described herein is that they provide long term electrical and mechanical protection against heat and moisture exposure. It has been found that the mechanical and electrical properties of the multi-layered integrated films provided herein do not degrade or only degrade to a comparatively low degree after exposure to extreme heat and moisture conditions.

Some embodiments of the multi-layered integrated films described herein have a dielectric breakdown voltage of at least 10 kV or at least 20 kV.

Some embodiments of the multi-layered integrated films described herein have a total thickness between about 0.22 mm and about 0.80 mm. In some embodiments, the total thickness of the integrated film is between about 0.35 mm and about 0.70 mm. In some embodiments, the total thickness of the integrated film is between about 0.40 mm and about 0.65 mm. It is an advantage of the present disclosure that integrated films with such a small thickness provide at least some of the advantageous properties described herein.

The multi-layered integrated films described herein provide mechanical protection of the solar module. Some embodiments of the multi-layered integrated films have an elongation at break of at least 50% and a tensile strength of at least 20 MPa.

In some embodiments, at least a portion of the multi-layered integrated films described herein is surface treated. Surface treatment may be carried out to improve the compatibility or adhesion to another surface or to provide a functional or decorative pattern or structure. Exemplary surface treatments include, for example, a plasma treatment (e.g., a Corona treatment that may be carried out under air or nitrogen atmosphere).

Some embodiments of the multi-layered integrated films described herein have smooth surfaces on one or both external sides. Some embodiments of the multi- layered integrated films described herein have rough surfaces on one or both external sides. Rough surfaces may facilitate deaeration during the lamination process when the integrated film is included in a solar cell module. Rough surfaces can be created by mechanical embossing or by melt fracture during extrusion of the sheets followed by quenching so that surface roughness is retained during handling.

Methods of Making the Multi-layered Integrated Films

The films of the present disclosure can be manufactured using known techniques in the art of film forming, including coating and curing on a release liner and extrusion coating. In some embodiments, the films are extruded. In some exemplary embodiments, the films of the present disclosure are delivered in film form. In some exemplary embodiments, the films of the present disclosure include a standard matte finish. In some exemplary embodiments, the films of the present disclosure are provided on a release liner.

The films of the present disclosure may be used in a solar module. The solar module may be of any type known in the art. In some embodiments, the films or compositions described herein can be used as an adhesive for a solar module. In such uses, the films or compositions may be referred to as an "assembly adhesive," since they are used to assemble and hold together at least two elements of the solar module.

As used herein, the terms "a", "an", and "the" are used interchangeably and mean one or more; "and/or" is used to indicate one or both stated cases may occur, for example A and/or B includes, (A and B) and (A or B). As used herein, the terms "comprises," "comprising," "includes," "including," "containing," "characterized by," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus and including equivalents.

All references mentioned herein are incorporated by reference.

Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the present disclosure and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. Further, any numerical range recited herein is intended to include and to specifically disclose the end points specified and also all integers and fractions within that range. For example, a range of from 1% to 50% is intended to be an abbreviation and to expressly disclose the values 1% and 50% and also the values between 1% and 50%, such as, for example, 2%, 40%, 10%, 30%, 1.5 %, 3.9 % and so forth.

Various embodiments and implementation of the present disclosure are disclosed. The disclosed embodiments are presented for purposes of illustration and not limitation. The implementations described above and other implementations are within the scope of the following claims. One skilled in the art will appreciate that the present disclosure can be practiced with embodiments and implementations other than those disclosed. Those having skill in the art will appreciate that many changes may be made to the details of the above-described embodiments and implementations without departing from the underlying principles thereof. It should be understood that this disclosure is not intended to be unduly limited by the illustrative embodiments and examples set forth herein and that such examples and embodiments are presented by way of example only with the scope of the disclosure intended to be limited only by the claims set forth herein as follows. Further, various modifications and alterations of the present disclosure will become apparent to those skilled in the art without departing from the spirit and scope of the present disclosure. The scope of the present application should, therefore, be determined only by the following claims.

Claims

What is claimed is:

1. A multilayer, integrated film capable of use in a solar module, comprising:

a backsheet portion including:

a first outer layer including a fluoropolymer with a tensile modulus of less than 100,000 psi;

an intermediate layer including polyethylene terephthalate having at least two planar directions and a shrinkage of less than 1% in each planar direction when held for 15 minutes at 150°C measured in accordance with ASTM 2305-02; and

a second outer layer including an olefinic polymer of the formula CH₂=CHR", wherein R" is hydrogen or a Cns alkyl, and wherein the first outer layer and the second outer layer are bonded to opposing sides of the intermediate layer; and

an encapsulant portion including a polyolefin, a silane, one or more cross-linking agents, and a plasticizer.

2. A multilayer, integrated film capable of use in a solar module, comprising:

a backsheet portion including:

a first outer layer including a fluoropolymer with a tensile modulus of less than 100,000 psi;

an intermediate layer including a polyester having at least two planar directions and a first and second surface, wherein the intermediate layer has a shrinkage of less than about 1% in each planar direction when held for 15 minutes at 150°C measured in accordance with ASTM 2305-02; and

a second outer layer including an olefinic polymer, wherein the first outer layer and the second outer layer are bonded to opposing sides of the intermediate layer; and an encapsulant portion including a polyolefin, a silane, one or more cross-linking agents, and a plasticizer.

3. A multilayer, integrated film capable of use in a solar module, comprising:

a backsheet portion including one or more of a fluoropolymer, a polyester, and a polyamide; and

an encapsulant portion including a polyolefin, a silane, one or more cross-linking agents, and a plasticizer.

4. A multilayer, integrated film capable of use in a solar module, comprising: a backsheet portion including:

an outer layer including a fluoropolymer;

an intermediate layer including a polyester; and

an encapsulant portion including a polyolefin, a silane, one or more cross-linking agents, and a plasticizer.

5. The multilayer, integrated film of claim 4, wherein the outer layer has a

tensile modulus of less than 100,000 psi.

6. The multilayer, integrated film of any of the preceding claims, wherein the intermediate layer has a shrinkage of less than 1% in each planar direction when held for 15 minutes at 150° C measured in accordance with ASTM 2305-02.

7. A multilayer, integrated film capable of use in a solar module, comprising:

a backsheet portion including at least two of the following three layers:

a layer including a fluoropolymer;

a layer including a polyester; and

a layer including a polyamide; and

an encapsulant portion including a polyolefin, a silane, one or more cross-linking agents, and a plasticizer.

8. The multilayer, integrated film of any of claims 1-7, further comprising:

a second outer layer of an olefinic polymer of the formula CH₂=CHR", wherein R" is hydrogen or a Cns alkyl.

9. The multilayer, integrated film of any of the preceding claims, further comprising: a top layer including cross-linked polyethene homopolymers or copolymers, and wherein the cross-linked polyethene homopolymers or copolymers are selected from a group consisting essentially of (a) polyethene copolymers comprising more than 99% by mole of repeating units derived from ethene and (b) polyethene copolymers comprising at least 50% by mole of repeating units derived from ethene and further including one or more alkene comonomers.

10. The multilayer, integrated film of any the preceding claims, wherein the first outer layer comprises interpolymerized units of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride.

1 1. The multilayer, integrated film of any the preceding claims, wherein the first outer layer comprises interpolymerized units of tetrafluoroethylene and ethylene.

12. The multilayer, integrated film of any the preceding claims, further comprising a tie layer between at least one of the first outer layer and the intermediate layer and the second outer layer and intermediate layer.

13. The multilayer, integrated film of any the preceding claims, wherein the second outer layer comprises interpolymerized units of ethylene vinyl actetate.

14. The multilayer, integrated film of any the preceding claims, wherein the thickness of the second outer layer is greater than or about twice the combined thickness of the first outer layer and the intermediate layer.

15. The multilayer, integrated film of any the preceding claims, wherein the thickness of the backsheet portion is greater than 15 mils.

16. The multilayer, integrated film of any the preceding claims, wherein the

fluoropolymer has a tensile modulus of less than 80,000 psi.

17. The multilayer, integrated film of any the preceding claims, wherein the shrinkage of the backsheet portion is less than 1% at 150°C when held for 15 minutes measured in accordance with ASTM 2305-02.

18. The multilayer, integrated film of any the preceding claims, wherein the backsheet portion and the encapsulant portion are coextruded.

19. The multilayer, integrated film of any the preceding claims, further including at least one of flame retardants and anti-dripping agents.

20. The multilayer, integrated film of any the preceding claims, wherein the backsheet portion and the encapsulant portion are bonded together.

21. The multilayer, integrated film of any the preceding claims, wherein the plasticizer in the encapsulant portion is non-polar.

22. The multilayer, integrated film of any the preceding claims, wherein the plasticizer in the encapsulant portion is selected from a group consisting essentially of ethylene/a-olefin copolymers and C4-C 10 polyolefm homopolymers.

23. The multilayer, integrated film of any the preceding claims, wherein the plasticizer in the encapsulant portion has a Tg<-50°C.

24. The multilayer, integrated film of any the preceding claims, wherein the plasticizer in the encapsulant portion has a Tg<-70°C.

25. The multilayer, integrated film of any the preceding claims, wherein the plasticizer in the encapsulant portion is liquid at 20°C.

26. The multilayer, integrated film of any the preceding claims, wherein the polyolefm in the encapsulant portion is an ethylene/a-olefin copolymer.

27. The multilayer, integrated film of claim 26, wherein the a-olefin moiety of the ethylene/a-olefin copolymer includes four or more carbons.

28. The multilayer, integrated film of claim 26, wherein the ethylene/a-olefin copolymer is a low crystalline ethylene/a-olefin copolymer.

29. The multilayer, integrated film of claim 26, wherein the low crystalline ethylene/a- olefin copolymer has a DSC peak melting point of less than or equal to 50°C.

30. The multilayer, integrated film of claim 26, wherein the low crystalline ethylene/a- olefin copolymer is a butene a-olefin.

31. The multilayer, integrated film of any the preceding claims, wherein the encapsulant portion includes greater than 70% by weight of low crystalline ethylene/a-olefin copolymer.

32. The multilayer, integrated film of any the preceding claims, wherein the silane in the encapsulant portion is an unsaturated alkoxysilane.

33. The multilayer, integrated film of claim 32, wherein the unsaturated alkoxysilane is an acrylic alkoxysilane.

34. The multilayer, integrated film of any the preceding claims, wherein the one or more cross-linking agents in the encapsulant portion are one of a thermal curative and a photo-curative.

35. The multilayer, integrated film of claim 34, wherein the thermal curative is a peroxide.

36. The multilayer, integrated film of any the preceding claims, wherein the encapsulant portion further includes a coagent.

37. The multilayer, integrated film of any the preceding claims, wherein the encapsulant portion further includes an additional resin.

38. The multilayer, integrated film of claim 37, wherein the additional resin is an additional low crystalline ethylene/a-olefin copolymer.

39. The multilayer, integrated film of claim 37, wherein the additional resin is one of an ethylene/butene copolymer and an ethylene/octene copolymer.

40. The multilayer, integrated film of any the preceding claims, wherein the encapsulant portion includes multiple layers.

41. The multilayer, integrated film of any the preceding claims in a solar cell module.

42. The multilayer, integrated film of any of the preceding claims further including an olefinic layer.

43. A solar module, comprising:

one or more solar cells; and

the multilayer, integrated film of any the preceding claims.

A method of making a multilayer, integrated film, comprising: coextruding the backsheet portion and the encapsulant portion to form the multilayer, integrated film of any the preceding claims; and

cross-linking the coextrusion.

45. A method of making a solar module, comprising:

vacuum laminating the multilayer, integrated film of any of the preceding claims to a solar module.

46. A method of making a multilayer, integrated film, comprising:

assembling the backsheet portion and the encapsulant portion to form the multi-layered film of any of the preceding claims using at least one of laminating or adhesion; and

cross-linking the multilayer, integrated film.