WO2014075076A1

WO2014075076A1 - Photovoltaic cell module

Info

Publication number: WO2014075076A1
Application number: PCT/US2013/069695
Authority: WO
Inventors: William R. Blackwood; Richard James; Barry M. KETOLA; Jacob MILNE; Elizabeth A. ORLOWSKI
Original assignee: Dow Corning Corporation
Priority date: 2012-11-12
Filing date: 2013-11-12
Publication date: 2014-05-15

Abstract

A photovoltaic cell module and a method of forming the module are provided. The module includes a first outermost layer and a photovoltaic cell disposed on the first outermost layer. The module also includes a second outermost layer disposed on the photovoltaic cell sandwiching the photovoltaic cell between the second outermost layer and the first outermost layer. The second outermost layer is present in a coating weight of from 3 to 75 grams per meter squared (g/m2) of the outward facing surface of said backsheet. Furthermore, the second outermost layer consists essentially of a silicone. The backsheet includes an organic polymer. The photovoltaic cell module passes the Wet Leakage Current Test at a voltage of at least 1000 V using IEC 61215 after humidity cycling for 1,000 hours.

Description

PHOTOVOLTAIC CELL MODULE

[0001] Photovoltaic cells are included in photovoltaic cell modules that typically also include tie layers, substrates, superstates, and/or additional materials that provide strength and stability. However, these materials tend to be expensive. Use of less expensive materials has historically caused photovoltaic cell modules to fail one or more physical tests, such as the well known Wet Leakage Current Test. Accordingly, there remains an opportunity to develop an improved photovoltaic cell module.

SUMMARY OF THE DISCLOSURE

[0002] The instant disclosure provides a photovoltaic cell module including a first outermost layer having a light transmittance of at least 70 percent as determined by UV/Vis spectrophotometry using ASTM E424-71 (2007). The photovoltaic cell module also includes a photovoltaic cell disposed on the first outermost layer, a backsheet disposed on the photovoltaic cell, and a second outermost layer opposite the first outermost layer. The second outermost layer is disposed on an outward facing surface of the backsheet sandwiching the photovoltaic cell and the backsheet between the second outermost layer and the first outermost layer. The second outermost layer is present in a coating weight of from 3 to 75 grams per meter squared (g/m²) of the outward facing surface of the backsheet. Furthermore, the second outermost layer consists essentially of a silicone. The backsheet includes an organic polymer. The photovoltaic cell module passes the Wet Leakage Current Test at a voltage of at least 1000 V using IEC 61215 after humidity cycling for 1,000 hours. This disclosure also provides a method of forming the photovoltaic cell module. The method includes the step of assembling the first outermost layer, the photovoltaic cell, the backsheet, and the second outermost layer.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0003] The present disclosure provides a photovoltaic cell module (hereinafter referred to as a "module") and a method of forming the module. A series of modules, e.g. at least two modules, may be electrically connected and form a photovoltaic array. The photovoltaic array may be planar or non-planar and typically functions as a single electricity producing unit wherein the modules are interconnected in such a way as to generate voltage. The present disclosure may include any one or more components, elements, method steps, compounds, or chemistries as described in the concurrently filed U.S. Provisional Application entitled "Photovoltaic Cell Module" designated as Attorney Docket Number DC 11520 PSP1, which is expressly incorporated by reference herein in its entirety in non-limiting embodiments. [0004] The module may have various physical properties. Typically, the module passes the Wet Leakage Current Test at a voltage (V) of at least 1000, 1025, 1050, 1075, 1100, 1125, 1150, 1175, 1200, 1225, 1250, 1275, 1300, 1325, 1350, 1375, 1400, 1425, 1450, 1475, 1500, V using IEC 61215 after humidity cycling for 1,000, 1,100, 1,200, 1,300, 1,400, 1,500, 1,600, 1,700, 1,800, 1,900, or 2,000, hours. As is known in the art, the wet leakage current test includes placing a module in an aqueous solution and applying an electrical field, e.g. a 1000 V field, and allowing the field to be applied for two minutes after which a current reading is taken. For larger modules, the wet leakage insulation resistance typically must be greater than 40 mega ohms/m². For smaller modules, the wet leakage resistance typically must be greater than 400 mega ohms/m². This test is typically performed during thermal cycle and damp heat aging initially and at all the test point intervals through two times IEC (TC 400, DH 2000).

[0005] The module may exhibit a water vapor transmission rate (WVTR) of 5 to 12, 6 to 11, 7 to 10, 8 to 9, 5, 6, 7, 8, 9, 10, 11, or 12, grams per meters squared per day (g/m²/day) according to any method known in the art. More specifically, the aforementioned WVTR values may apply to the backsheet, the second outermost layer, or the combination of the backsheet and the second outermost layer, e.g. the bi-layer backsheet described in greater detail below. The differently, the module as a whole may be evaluated to determine WVTR and/or one or more of the backsheet, the second outermost layer, or the combination of the backsheet and the second outermost layer, may be evaluated to determine WVTR.

[0006] The module includes a first (outermost) layer, a photovoltaic cell disposed on the first (outermost) layer, a backsheet disposed on the photovoltaic cell, and a second outermost layer opposite the first (outermost) layer. The second outermost layer is disposed on an outward facing surface of the backsheet sandwiching the photovoltaic cell and the backsheet between the second outermost layer and the first (outermost) layer.

[0007] The module may be described as set forth immediately above or may alternatively be described as further including one or more electrical components (e.g. leads, wires, electrodes, junction boxes), one or more additional structural components (e.g. frames, mounts), one or more tie layers, and/or any components typically found in or near photovoltaic cell modules during production, installation, and/or use. The module further including one or more additional electrical or structural components may be described as a photovoltaic cell panel.

First (Outermost) Layer:

[0008] The module includes a first layer that has a light transmittance of at least 70 percent as determined using UV/Vis spectrophotometry using ASTM E424-71 (2007). In various embodiments, the first layer has a light transmittance of at least 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99, percent, wherein the light transmittance is at most 100 percent. In an alternative embodiment, the first layer has a light transmittance of approximately 100 percent (e.g. from 99.5% to 100.0%). Typically, the first layer is further defined as a first "outermost" layer when the first layer is an exterior layer of the module. However, the first layer may be at least partially coated with silicon and oxygen based materials (SiO_x) which may be any one or more silicones, i.e., linear and/or branched polyorganosiloxanes, described below or may be different. In this case, the coating of the SiO_x material would be the "outermost" layer and the first layer would be, at least in some areas, a layer interior to the coating. Simply for descriptive, but non-limiting purposes, the first layer is described as the first "outermost" layer below. However, the terminology first layer and first outermost layer may be interchangeable herein in various embodiments.

[0009] The first outermost layer may be, include, consist essentially of (and not include organic monomers or polymers), or consist of, silicone, i.e., linear and/or branched polyorganosiloxanes. The silicone is not particularly limited and may be any of the silicones described below or may be different. In one embodiment, the first outermost layer is, includes, consists essentially of (and does not include organic monomers or polymers or silicones), or consists of, glass (e.g. an amorphous soda-lime glass). In one embodiment, the first outermost layer is not limited to the aforementioned compounds and may include any compound or composition known in the art so long as the first outermost layer has a light transmittance of at least 70 percent using ASTM E424-71 (2007).

Photovoltaic Cell:

[0010] The module also includes a photovoltaic cell. The photovoltaic cell may be disposed on the first outermost layer or the first outermost layer may be disposed on the photovoltaic cell. In one embodiment, the photovoltaic cell is disposed directly on the first outermost layer, i.e., in direct contact with the first outermost layer, e.g. by an encapsulant layer. In another embodiment, the photovoltaic cell is spaced apart from the first outermost layer yet still disposed "on" the first outermost layer. The photovoltaic cell may be disposed on, and in direct contact with (i.e., directly applied to), the first outermost layer via chemical vapor deposition and/or physical sputtering. Alternatively, the photovoltaic cell may be formed apart from the first outermost layer and/or the module and later disposed on the first outermost layer.

[0011] The photovoltaic cell typically has a thickness of from 50 to 250, more typically of from 100 to 225, and most typically of from 175 to 225, micrometers. In one embodiment, the photovoltaic cell has a length and width of 125 mm each. In another embodiment, the photovoltaic cell has a length and width of 156 mm each. The photovoltaic cell is not limited to these dimensions.

[0012] The photovoltaic cell may include large-area, single-crystal, single layer p-n junction diodes. These photovoltaic cells are typically made using a diffusion process with silicon wafers. Alternatively, the photovoltaic cell may include thin epitaxial deposits of (silicon) semiconductors on lattice-matched wafers. In this embodiment, the photovoltaic cell may be classified as for use in either space or terrestrial applications and typically has AM0 efficiencies of from 7 to 40%. Further, the photovoltaic cell may include quantum well devices such as quantum dots, quantum ropes, and the like, and also include carbon nanotubes. Still further, the photovoltaic cell may include mixtures of polymers and nano particles that form a single multi- spectrum layer which can be stacked to make multi-spectrum solar cells more efficient and less expensive.

[0013] The composition of the photovoltaic cell is not particularly limited and may include amorphous silicon, monocrystalline silicon, polycrystalline silicon, microcrystalline silicon, nanocrystalline silica, cadmium telluride, copper indium/gallium selenide/sulfide, gallium arsenide, polyphenylene vinylene, copper phthalocyanine, carbon fullerenes, and combinations thereof in ingots, ribbons, thin films, and/or wafers. The photovoltaic cell may also include light absorbing dyes such as ruthenium organometallic dyes. Most typically, the photovoltaic cell includes monocrystalline and polycrystalline silicon.

Backsheet:

[0014] The module also includes a backsheet disposed on the photovoltaic cell. Alternatively, the photovoltaic cell may be disposed on the backsheet. The backsheet may bind the first outermost layer and the photovoltaic cell and/or at least partially encapsulate the photovoltaic cell. The backsheet may be disposed directly on the photovoltaic cell, i.e., in direct contact with the photovoltaic cell, or may be spaced apart from the photovoltaic cell (e.g. by an encapsulant layer) yet still be disposed "on" the photovoltaic cell. In various embodiments, the backsheet is further described as a controlled bead disposed on the photovoltaic cell, e.g. a controlled bead of an organic polymer. The controlled bead is typically applied in a rectangular shape. However, the controlled bead may be formed in any shape. The controlled bead may be in contact with an interior portion of the first outermost layer, the photovoltaic cell, or both the first outermost layer and the photovoltaic cell thereby leaving a space along a perimeter of the first outermost layer, the photovoltaic cell, or both the first outermost layer and the photovoltaic cell that does not include the backsheet. In one embodiment, this space is approximately ½ inch in width. The backsheet and/or composition used to form the backsheet may be described as a matrix in which the fibers are disposed in and/or encapsulated by an organic polymer. In such an embodiment, the backsheet and/or composition used to form the backsheet, i.e., the "matrix," may be, include, consist essentially of, or consist of an organic polymer and still include the plurality of fibers.

[0015] The backsheet typically has a thickness of from 1 to 50, more typically of from 4 to 40, even more typically of from 3 to 30, and still more typically of from 4 to 15, and most typically of from 4 to 10, mils. The conversion for mils to various SI units is 0.0254 mm/mil or 25.4 microns/mil. The backsheet may be tacky or non-tacky and may be a gel, gum, liquid, paste, resin, or solid. In one embodiment, the backsheet is substantially free of entrapped air (bubbles). The terminology "substantially free" describes that the backsheet has no visible air bubbles when viewed with the naked eye or under lOx magnification. The backsheet may be formed from polymerizable organic monomers and may be cured or partially cured to be tacky or non-tacky and/or a gel, gum, liquid, paste, resin, or solid. In one embodiment, partial curing occurs when less than 90 percent of appropriate (i.e., expected) reactive moieties react. In another embodiment, curing occurs when at least 90 percent of appropriate (i.e., expected) reactive moieties react, as determined by ¹³C NMR.

[0016] The backsheet includes the organic polymer. The terminology "organic polymer" describes a substance composed of macromolecules having at least five repeat units; wherein the macromolecules are homochain molecules, heterochain molecules, or a mixture thereof, wherein the homochain molecules have only carbon atoms in their chains and the heterochain molecules have only carbon atoms and one or more heteroatoms other than a silicon atom in their chains, The heteroatom(s) in the chains of the heterochain molecules may be oxygen, nitrogen, or both. Each chain of the homochain and heterochain molecules independently may be linear or branched. The backsheet may be, include, consist essentially or, or consist of polyethylene terephthalate, polyethylene naphthalate, polyvinyl fluoride, and/or ethylene vinyl acetate, and/or Tedlar^®, or any other organic polymer, and may be free of silicone. Typically, the backsheet is free of all polymers that are not organic polymers. The differently, the backsheet is typically an organic polymer or consists essentially of an organic polymer (and is free from non-organic polymers), or consists of one or more organic polymers.

Second Outermost Layer:

[0017] The module also includes a second outermost layer. In one embodiment, this layer is described as an anti-soiling layer. Alternatively, the second outermost layer may be described as a top coat layer (vis-a-vis the backsheet). The second outermost layer can be described as a bottom layer of the module, i.e., the layer of the module disposed furthest away from the sun when the module is disposed in front of the sun in use. The second outermost layer is disposed opposite the first outermost layer and is disposed on an outward facing surface of the backsheet sandwiching the photovoltaic cell and the backsheet between the second outermost layer and the first outermost layer. The second outermost layer may be disposed on and in direct contact with the backsheet or may be disposed on, but spaced apart from, the backsheet, e.g. a tie layer. In one embodiment, the second outermost layer is disposed on but spaced apart from the backsheet and the module includes an intermediate layer, such as a tie layer, sandwiched between the second outermost layer and the backsheet. One of the tie layers and/or encapsulants described below may function as the second outermost layer.

[0018] Typically, the second outermost layer can be described as a bottom layer of the module, i.e., the layer of the module disposed furthest away from the sun. The backsheet and the second outermost layer each have a thickness. In various embodiments, the thickness of the second outermost layer is at least 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 2, microns, at one or more points along the second outermost layer. In various embodiments, the second outermost layer will be present across a portion or all of the backsheet in a thickness varying from 0.5 to 2 microns.

[0019] If the backsheet includes fibers, the thickness of the second outermost layer may be measured starting from the bottom of a trough in the fibers to a peak of the second outermost layer. Alternatively, if the backsheet is free of fibers and/or substantially smooth, the thickness may be measured from a surface of the backsheet to an upper surface of the second outermost layer. The thickness of the second outermost layer may be measured by measuring a total thickness of the (backsheet and the second outermost layer ) and subtracting a thickness of the backsheet itself. Alternatively, thickness may be measured using SEM techniques and any appropriate ASTM test. For example, a sample may be mounted on an SEM stub and coated with 15 nm of Pt/Pd. The JEOL 6335 FE-SEM may be then set to 5 kv, 15 mm working distance, and an aperture of 4. SEM images may be captured between 25x and 500x magnification.

[0020] In still other embodiments, the second outermost layer is present in a coating weight, i.e., in an amount in grams (g) relative to the surface area in square meters (m²) of the portion of the backsheet in contact with the second outermost layer of less than 75, 70, 65, 60, 55, 50, 45, 40, 35, 30, 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1, g/m². In further embodiments, the second outermost layer is present in an amount of from 5 to 75, 10 to 70, 15 to 65, 20 to 60, 25 to 55, 30 to 50, 35 to 45, 40 to 45, 1 to 15, 2 to 14, 3 to 12, 4 to 11, 5 to 10, 6 to 9, or 7 to 8 g/m². Alternatively, the second outermost layer may be generally described as having about 1 micron of thickness for about every 10 grams per meter squared of coating weight, as can be measured and appreciated by those of skill in the art, e.g. as measured by those methods described above.

[0021] The second outermost layer may exhibit a coefficient of friction, as described above relative to the second outermost layer of 0.1 to 0.7, 0.2 to 0.6, 0.3 to 0.5, 0.4 to 0.5, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, or 0.7, against itself measured according to ISO 8295. The terminology "against itself describes that a material, e.g. the second outermost layer, is evaluated for coefficient of friction by rubbing a first sample of the material against a second sample of the identical material. Typically, the lower the coefficient of friction, the less dirt, soil, particulates are retained by (e.g. stuck to) the second outermost layer.

[0022] The second outermost layer may be, include, consist essentially of, or consist of a (or at least one) silicone (linear and/or branched polyorganosiloxanes), e.g. a first silicone and/or a second silicone. The terminology "consist essentially of describes that the second outermost layer may be free of, or include less than 10, 5, 1, 0.1, 0.05, or 0.01, weight percent of, polymers, other than silicones, that would otherwise affect the physical properties of the silicone, as described above. Non-limiting examples of such polymers include organic polymers, Tedlar, poly(alkylenes), PET, plastics, and the like. The silicone of the second outermost layer may be formed from a silicone composition that is cured, i.e. linear and/or branched polyorganosiloxanes that are cured.

[0023] The silicone composition used to form the second outermost layer may include, but is not limited to, silanes, siloxanes, silazanes, silylenes, silyl radicals or ions, elemental silicon, silenes, silanols, polymers thereof, and combinations thereof. Typically, as used throughout, the terminology "silicone" may describe one or more linear and/or branched polyorganosiloxanes. In addition, the silicone composition may be cured, partially cured, or completely cured by any mechanism known in the art including, but not limited to, free radical reactions, hydrosilylation reactions, condensation or addition reactions, heat curing, UV curing, and combinations thereof. In various non-limiting embodiments, the silicone compositions may be as described in U.S. App. Pub. No. 2011/0061724, which is expressly incorporated herein in its entirety relative to these non-limiting embodiments.

[0024] The silicone composition may be further independently described as a curable silicone composition including, but are not limited to, hydrosilylation-curable silicone compositions, condensation-curable silicone compositions, and free-radical curable silicone compositions such as radiation-curable silicone compositions and light (e.g. UV light) curable compositions, and peroxide-curable silicone compositions. [0025] A hydrosilylation-curable silicone composition typically includes an organopolysiloxane having an average of at least two silicon-bonded alkenyl groups or silicon- bonded hydrogen atoms per molecule; an organosilicon compound in an amount sufficient to cure the organopolysiloxane, wherein the organosilicon compound has an average of at least two silicon-bonded hydrogen atoms or silicon-bonded alkenyl groups per molecule capable of reacting with the silicon-bonded alkenyl groups or silicon-bonded hydrogen atoms in the organopolysiloxane; and a catalytic amount of a hydrosilylation catalyst.

[0026] A condensation-curable silicone composition typically includes an organopolysiloxane having an average of at least two silicon-bonded hydrogen atoms, hydroxy groups, or hydrolysable groups per molecule and, optionally, a cross-linking agent having silicon-bonded hydrolysable groups and/or a condensation catalyst.

[0027] A radiation-curable silicone composition typically includes an organopolysiloxane having an average of at least two silicon-bonded radiation-sensitive groups per molecule and, optionally, a cationic or free -radical photoinitiator depending on the nature of the radiation- sensitive groups in the organopolysiloxane.

[0028] A peroxide-curable silicone composition typically includes an organopolysiloxane having silicon-bonded unsaturated aliphatic hydrocarbon groups and an organic peroxide.

[0029] The silicone composition can be cured by exposing the composition to ambient temperature, elevated temperature, moisture, or radiation, depending on the type of curable silicone composition.

[0030] Hydrosilylation-curable silicone compositions can be cured by exposing the composition to a temperature of from room temperature (about 23 + 2 °C) to 250 °C, alternatively from room temperature to 150 °C, alternatively from room temperature to 115 °C, at atmospheric pressure. The silicone composition is generally heated for a length of time sufficient to cure (cross-link) the organopolysiloxane. For example, the film is typically heated at a temperature of from 100 to 150 °C for a time of from 0.1 to 3 hours.

[0031] Condensation-curable silicone compositions cure depending on the nature of the silicon-bonded groups in the organopolysiloxane. For example, when the organopolysiloxane includes silicon-bonded hydroxy groups, the composition can be cured (i.e., cross-linked) by heating the composition. The composition can typically be cured by heating it at a temperature of from 50 to 250 °C, for a period of from 1 to 50 hours. When the condensation-curable silicone composition includes a condensation catalyst, the composition can typically be cured at a lower temperature, e.g., from room temperature (about 23 ± 2 °C) to 150 °C. [0032] Condensation-curable silicone composition typically include an organopolysiloxane having silicon-bonded hydrogen atoms and can be cured by exposing the composition to moisture or oxygen at a temperature of from 100 to 450 °C for a period of from 0.1 to 20 hours. When the condensation-curable silicone composition includes a condensation catalyst, the composition can typically be cured at a lower temperature, e.g., from room temperature (about 23 ± 2 °C) to 400 °C.

[0033] Further, when the curable silicone composition is a condensation-curable silicone composition comprising an organopolysiloxane having silicon-bonded hydrolysable groups, the composition can be cured by exposing the composition to moisture at a temperature of from room temperature (about 23 + 2 °C) to 250 °C, alternatively from 100 to 200 °C, for a period of from 1 to 100 hours. For example, the silicone composition can typically be cured by exposing it to a relative humidity of 30% at a temperature of from about room temperature (about 23 + 2 °C) to 150 °C, for a period of from 0.5 to 72 hours. Cure can be accelerated by application of heat, exposure to high humidity, and/or addition of a condensation catalyst to the composition.

[0034] Radiation-curable silicone compositions can be cured by exposing the composition to an electron beam. Typically, the accelerating voltage is from about 0.1 to 100 kiloelectron volt (keV), the vacuum is from about 10 to 10^"3 Pascals (Pa), the electron current is from about 0.0001 to 1 ampere, and the power varies from about 0.1 watt to 1 kilowatt. The dose is typically from about 100 microcoulombs per centimeter squared (microcoulomb/cm^) to 100 coulomb per centimeter squared (coulomb/cm^), alternatively from about 1 to 10 coulombs/cm^. Depending on the voltage, the time of exposure is typically from about 10 seconds to 1 hour.

[0035] Also, when the radiation-curable silicone composition further includes a cationic or free radical photoinitiator, the composition can be cured by exposing it to radiation having a wavelength of from 150 to 800 nanometers (nm), alternatively from 200 to 400 nm, at a dosage sufficient to cure (cross-link) the organopolysiloxane. The light source is typically a medium pressure mercury-arc lamp. The dose of radiation is typically from 30 to 1,000 millijoules per centimeter squared (mJ/cm^), alternatively from 50 to 500 mJ/cm^. Moreover, the silicone composition can be externally heated during or after exposure to radiation to enhance the rate and/or extent of cure.

[0036] When the curable silicone composition is a peroxide-curable silicone composition, the composition can be cured by exposing it to a temperature of from room temperature (about 23 ± 2 °C) to 180 °C, for a period of from 0.05 to 1 hours. [0037] In one embodiment, the curable silicone composition, and/or the second outermost layer is, includes, consists essentially of, or consists of, the following reaction product of Parts A and B, e.g. in a 1 : 1 mixture by weight:

Part A:

4.8 to 10 wt Dimethylvinylsiloxy-terminated Dimethyl, Methylvinyl Siloxane

46 to 75 wt Dimethylvinyl terminated poly(dimethylsiloxane)

.007 to 1 wt 1, 3-Diethenyl-l ,l, 3, 3-tetramethyldisiloxane platinum complexes

16 to 30 wt Dimethylvinylated and Trimethylated Silica

0 to 30 wt Titanium Dioxide

Part B:

.007 to 1 wt Ethynyl Cyclohexanol

.5 to 6 wt Trimethyl terminated poly(dimethylsiloxane)

7 to 15 wt Trimethylsiloxy-terminated Dimethyl, Methylhydrogen Siloxane,

6 to 12 wt Dimethylvinylsiloxy-terminated Dimethyl, Methylvinyl Siloxane,

37 to 60 wt Dimethylvinylsiloxy-terminated poly(dimethylsiloxane)

16 to 30 wt Dimethylvinylated and Trimethylated Silica

0 to 30 wt Titanium Dioxide

Any of the aforementioned values may, for example, vary by 1, 2, 3, 4, 5, 10, 15, 20, or 25+ % in varying non-limiting embodiments. All values, and ranges of values, between and including the aforementioned values are also hereby expressly contemplated in various non-limiting embodiments.

[0038] In a further embodiment, the curable silicone composition and/or the second outermost layer is, includes, consists essentially of, or consists of, the following reaction product of Parts A and B in a 1 : 1 mixture by weight:

Part A:

95.0 to 99.9 Dimethyl Siloxane, Dimethylvinylsiloxy- terminated polymer

0.1 to 0.3 l,3-Diethenyl-l ,l,3,3-Tetramethyldisiloxane complexes (Platinum)

0.5 to 3 Methacryloxypropyltrimethoxysilane

Part B:

95.0 to 99.9 Dimethyl Siloxane, Dimethylvinylsiloxy- terminated polymer

1.0 to 3.0 Dimethyl, Methylhydrogen Siloxane, trimethylsiloxy-terminated

0.01 to 1 Tetramethyltetravinylcyclotetrasiloxane

[0039] In various non-limiting embodiments, the silicone of the second outermost layer includes one or more components, compounds, systems, additives, catalysts, fillers as described in one or more of U.S. 6,354,620, 6,268,300, 2006/0276585, and/or JP 2010083946, each individually expressly incorporated herein by reference. In one embodiment, a flame resistant filler, or combination of fillers, is utilized which may allow the module to pass a Class A fire rating.

[0040] In one embodiment, the silicone of the second outermost layer is formed from reacting

(A) a polyorganosiloxane having at least 2 silicon-bonded alkenyl groups per molecule and

(B) a polyorganohydrogensiloxane including at least 2 silicon-bonded hydrogen groups per molecule, in the presence of (C) a catalyst capable of promoting the reaction between (A) and (B).

[0041] The polyorganosiloxane (A) is typically a liquid and includes at least 2 alkenyl groups in each molecule. Each alkenyl group is typically independently a vinyl, allyl, methacryl, or hexenyl group. Non-alkenyl Si-bonded organic groups present in (A) may be alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, isopropyl, isobutyl, cyclopentyl, and cyclohexyl groups; aryl groups such as phenyl and naphthyl groups; aralkyl groups such as benzyl and 1- phenylethyl groups; halogenated alkyl groups such as chloromethyl, 3-chloropropyl, 3,3,3- trifluoropropyl, and nonafluorobutylethyl groups; halogenated aryl groups such as 4- chlorophenyl, 3,5-dichlorophenyl, and 3,5-difluorophenyl groups; and aryl groups substituted by halogenated alkyl, such as 4-chloromethylphenyl and 4-trifluoromethylphenyl groups. The molecular structure of the polyorganosiloxane (A) is typically straight chain, but may include partial chain branching. Each of the at least two alkenyl groups may be bonded in terminal or pendant positions. The polyorganosiloxane (A) may be further defined as a dimethylvinylsiloxy- endblocked polydimethylsiloxane, dimethylvinylsiloxy-endblocked dimethylsiloxane- methylphenylsiloxane copolymers, dimethylvinylsiloxy-endblocked dimethylsiloxane-3,3,3- trifluoropropylmethylsiloxane copolymers, dimethylvinylsiloxy-endblocked dimethylsiloxane- methylvinylsiloxane copolymers, trimethylsiloxy-endblocked dimethylsiloxane- methylvinylsiloxane copolymers, or trimethylsiloxy-endblocked dimethylsiloxane- hexenylmethylsiloxane copolymers. Most typically, the dynamic viscosity of polyorganosiloxane (A) at 25°C is from 100 to 500,000, from 100,000 to 500,000, from 100,000 to 200,000, from 150,000 to 200,000, millipascal-seconds (mPa.s). [0042] In one embodiment, (A) includes 10 to 50 mole % of vinylmethylsiloxane units based on a total number of moles of (A). In another embodiment, (A) includes both silicon-bonded vinyl groups and silicon-bonded hydroxyl groups in a single molecule. In still another embodiment, (A) includes both silicon-bonded vinyl groups and silicon-bonded hydroxyl groups in a single molecule.

[0043] The polyorganohydrogensiloxane (B) typically acts as a cross-linking agent in the presence of the catalyst (C). For example, hydrogen atoms bonded to silicon atoms of (B) may undergo an addition reaction with the alkenyl groups bonded of (A) resulting in cross-linking and cure. Typically, (B) includes at least two hydrogen atoms bonded to silicon atoms in each molecule. However, if there are only two alkenyl groups on (A), there are typically more than two silicon-bonded hydrogen groups on (B). Organic groups other than the hydrogen atoms bonded to silicon atoms which may be present in (B) include alkyl groups such as methyl groups, ethyl groups or propyl groups; aryl groups such as phenyl groups or tolyl groups; and substituted alkyl groups such as 3,3,3-trifkioropropylgroups or 3-chloropropyl groups.

[0044] The molecular structure of (B) may be linear or may include branching, cyclic or network forms. (B) may be further defined as a trimethylsiloxy-endblocked polymethydrogensiloxane, trimethylsiloxane-endblocked dimethylsiloxane- methylhydrogensiloxane copolymer, dimethylphenylsiloxy-endblocked methylphenylsiloxane- methylhydrogensiloxane copolymer, cyclic polymethylhydrogensiloxane, and copolymers composed of dimethylhydrogensiloxy and S1O4_/2 units. Most typically, the dynamic viscosity of (B) at 25°C is from 3 to 10,000 mPa.s. Furthermore, the amount of (B) that is typically utilized is from 0.5: 1 to 15: 1 or from 1 : 1 to 10: 1 , as a ratio of the number of moles of hydrogen atoms bonded to silicon atoms (in (B)) to the number of moles of alkenyl groups bonded to silicon atoms (in (A)).

[0045] The catalyst (C) may be any substance that accelerates an addition reaction between (A) and (B) above. In various embodiments, (C) is a platinum compound, rhodium compound, and/or palladium compound, e.g. chloroplatinic acid, alcohol-modified chloroplatinic acid, chloroplatinic acid-olefin complexes, and diketonate complexes of platinum. (C) is typically utilized in amounts of from 0.1 to 1,000 parts per million (ppm), and typically 1 to 50 ppm platinum atoms, based on a weight of (A).

[0046] In other embodiments, the silicone of the second outermost layer is formed from reaction of (I) an organopolysiloxane having a siloxane backbone of degree of polymerisation no more than 150 and being end-blocked with at least two silicon-bonded groups R, wherein R denotes an olefinically unsaturated hydrocarbon substituent, an alkoxy group or a hydroxyl group, and (II) a cross-linking organosilicon material having at least 3 silicon-bonded reactive groups, in the presence of (III) a catalyst and (IV) a filler. Notably, the (III) catalyst and the (IV) filler are typically different. In such an embodiment, the (IV) filler is then present in the silicone of the second outermost layer.

[0047] Typically, the (I) organopolysiloxane includes units of the general formula R^J _a

SiC>4-a-_b/2, wherein R¹ is a monovalent hydrocarbon group having up to 18 carbon atoms, R² is a monovalent hydrocarbon or hydrocarbonoxy group or a hydroxyl group, a and b have a value of from 0 to 3, and the sum of a+b is no more than 3. In one embodiment, (I) has the structure set forth below:

wherein R¹ and R² are described above and wherein x is an integer of no more than 148, typically having a value of from 5 to 100, more typically from 8 to 50. In various embodiments, R¹ is an alkyl or aryl group having from 1 to 8 carbon atoms, e.g. methyl, ethyl, propyl, isobutyl, hexyl, phenyl or octyl. In other embodiments, at least 50%, 75%, 90%, 95%, or about 100%, of all R¹ groups are methyl groups. In further embodiments, R² is selected from a hydroxyl group, an alkoxy group or an aliphatically unsaturated hydrocarbon group. Alternatively, R² may be a hydroxyl group or alkoxy group having up to 3 carbon atoms suitable for condensation reactions, or an alkenyl or alkynyl group having up to 6 carbon atoms, more typically vinyl, allyl or hexenyl, suitable for addition reactions.

[0048] In various embodiments, the organopolysiloxane polymer (I) has at least two silicon- bonded alkenyl groups per molecule and may have a dynamic viscosity of less than 500 mPas, or from 4 to 100 mPas, at 25°C. Alternatively, (I) can be, or can be mixed with, higher viscosity materials (e.g. greater than 100 mPa.s). In still other embodiments, (I) may be a homopolymer, copolymer or mixtures thereof which include units of the general formula R¹ _aR³ _c Si0₄__a-_b 2 wherein R¹ and a are as described above, R³ is an alkenyl group having up to 8 carbon atoms and c is 0 or 1 provided that a+c is not greater than 3.

[0049] In still other embodiments, (I) can include at least one polymer containing vinylmethylsiloxane units, which can for example include from 0.5% or 1% by weight of the diorganosiloxane units of (A) up to 50 or even 100%. Mixtures of such vinylmethylsiloxane polymers can be used. For example, (I) in which 10 to 50 mole % of the siloxane units are vinylmethylsiloxane units can be used or (I) in which 1 to 10 mole % of the siloxane units are vinylmethylsiloxane units or a mixture can be used, or mixtures of both can be used. In various embodiments, (I) includes vinyldimethylsiloxy terminal groups and optionally other terminal groups such as trimethylsilyl.

[0050] In still other embodiments, (I) includes the following structure

wherein R¹ is as described above, R³ is an alkenyl group having from 2 up to 8 carbon atoms, with the formula -R⁴ _y— CH=CH₂, where R⁴ is a divalent hydrocarbon group having up to 6 carbon atoms, e.g. an alkylene group having up to 4 carbon atoms, y has a value of 0 or 1, and x has a value of from 5 to 100, 8 to 50, or 8 to 20. Alternatively, (I) can include a polysiloxane containing both silicon-bonded vinyl groups and silicon-bonded hydroxyl groups, for example a hydroxy-terminated poly(dimethyl, vinylmethyl siloxane).

[0051] Referring back to (II) the organosilicon compound, this compound is typically capable of reacting with (I) and may be a viscous or a free flowing liquid. Typically, (II) has a dynamic viscosity of less than 100 or about 2 to 55 mPas at 25°C. (II) may include one or more monomers, homopolymers, copolymers or mixtures thereof which include at least one unit of the general formula R¹ _aR⁵ Si0₄__a-_b 2 wherein R¹, a and b are as above and R⁵ is a hydrogen atom, a hydroxyl or an alkoxy group, except that where (II) is a monomer (e.g. a silane) a+b would be 4 and b would be at least 3.

[0052] Typically, (II) is chosen from silanes, low molecular weight organosilicon resins and short chain organosiloxane polymers. (II) usually includes at least 3 silicon-bonded substituents R⁵ that are capable of reacting with the silicon-bonded group R² of (I). If R² is a hydroxyl or alkoxy group, the reactive substituents on (II) typically are either alkoxy groups or hydroxyl groups, allowing the condensation to take place between (I) and (II).

[0053] Suitable but non-limiting examples of (II) are alkyltrialkoxy silanes, e.g. methyltrimethoxy silane, ethyltrimethoxy silane, methyltriethoxy silane or methyltrihydrosilane, and combinations thereof, organosilicon resins including tetrafunctional siloxane units (Q units) of the formula S1O4_/2 and monofunctional units (M units), short chain organosiloxane polymers such as short chain polyorganosiloxanes having at least 3 silicon-bonded alkoxy, hydroxyl or hydrogen atoms per molecule, e.g. trimethyl siloxane end-blocked polymethylhydrosiloxane having up to 20 carbon atoms, tetramethylcyclotetrasiloxane and silanol end-blocked dimethylsiloxane-methylsilanol copolymers, and combinations thereof. [0054] In still other embodiments, (II) is a short chain polyorganosiloxane having at least 3 silicon-bonded hydrogen atoms, typically having a silicon-bonded hydrogen atom on at least 40% of, more typically on the majority of silicon atoms in the molecule. In one embodiment, (II) is a substantially linear or cyclic compound. In other embodiments, (II) has the formula R⁷R⁶ ₂SiO(R⁶ ₂SiO)_p(R⁶HSiO) SiR⁶ ₂R⁷ or

wherein R⁶ is an alkyl or aryl group having up to 10 carbon atoms, R⁷ is R⁶ or a hydrogen atom, p has a value of from 0 to 20, q has a value of from 1 to 70, and there are at least 3 silicon- bonded hydrogen atoms present per molecule. In one embodiment, R⁶ is a lower alkyl group having no more than 3 carbon atoms, e.g. a methyl group, and R⁷ is R⁶ provided at least 3 of the R⁷ are hydrogen atoms. Typically, p and q have similar values or p=0 and q has a value of from 6 to 70, more typically 20 to 60, or where cyclic organosilicon materials are used, from 3 to 8.

[0055] Referring now to (III), the catalyst (III) may be any compound which catalyses the reaction between (I) and (II) above. Where the reaction is a condensation reaction, the catalyst may be any of the known condensation catalysts, e.g. acids, including sulphuric acid, hydrochloric acid, Lewis acids, bases, e.g. sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, tetrabutylphosphonium silanolate and amines, catalysts based on tin or titanium, e.g. dialkyltin dicarboxylic acids and tetraalkyl titanates. Particularly useful organotitanium compounds have organic groups attached to titanium through a titanium-oxygen- carbon linkage. The main types are ortho-esters, i.e. alcoholates and acylates in which the organic group is derived from a carboxylic acid. An organotitanium catalyst may also contain both types of the aforementioned groups attached to the same titanium atom. Operative organotitanium catalysts thus include those of the formula Ti(OR⁸)₄ wherein R⁸ is alkyl, alkoxyalkyl or acyl, for example tetraisopropyl titanate, tetramethoxy-ethoxytitanate and di- isopropyl diacetoxytitanate. The preferred organotitanium catalysts for use in this invention are the chelated or partially chelated titanium compounds. These materials are produced, for example by reacting an alcoholate as referred to above with an alpha- or beta-diketone or a derivative thereof.

[0056] Additional suitable catalysts (III) include Group VIII metal-based or noble metal catalysts e.g. rhodium, ruthenium, palladium, osmium, iridium or platinum containing catalysts. Platinum-based catalysts are particularly preferred and may take any of the known forms, ranging from platinum deposited onto carriers, for example powdered charcoal, to platinic chloride, salts of platinum, chloroplatinic acids and encapsulated forms thereof. A preferred form of platinum catalyst is chloroplatinic acid, platinum acetylacetonate, complexes of platinous halides with unsaturated compounds such as ethylene, propylene, organovinylsiloxanes, and styrene, hexamethyldiplatinum, PtCl₂, PtCl₃, PtCl₄, and Pt (CN)₃.

[0057] In even further embodiments, the silicone of the second outermost layer is formed from reacting (i, ii) addition-crosslinking organosilicon compounds in the presence of a (iii) catalyst. Referring to (i), this compound is typically an organosilicon compound that is linear, cyclic or branched, e.g. a siloxane that may include units of the formula R² _sR³ _tSiO ₍₄-_s-_t)/2 where R² in each occurrence may be the same or different and is an SiC bonded aliphatically unsaturated hydrocarbyl radical, R³ in each occurrence may be the same or different and is an optionally substituted SiC-bonded aliphatically saturated hydrocarbyl radical, s is 0, 1, 2 or 3, typically 0, 1 or 2, and t is 0, 1, 2 or 3, with the proviso that the sum total s+t is not more than 3 and two or more R² radicals are present per molecule. In various embodiments, R² represents hydrocarbyl radicals of 2 to 18 carbon atoms having aliphatic multiple bonding, such as vinyl, allyl, methallyl, 2-propenyl, 3-butenyl, 4-pentenyl, 5-hexenyl, butadienyl, hexadienyl, cyclopentenyl, cyclopentadienyl, cyclohexenyl, ethynyl, propargyl and 2-propynyl, this kind of R.sup.2 radical with 2 to 6 carbon atoms being particularly preferred, especially vinyl and allyl. In other embodiments, R³ represents optionally substituted aliphatically saturated monovalent hydrocarbyl radicals having 1 to 18 carbon atoms, more typically having 1 to 8 carbon atoms, especially methyl. Additional examples of R³ are alkyl radicals such as the methyl, ethyl, n- propyl, isopropyl, 1-n-butyl, 2-n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and tert-pentyl radicals; hexyl radicals such as n-hexyl; heptyl radicals such as n-heptyl; octyl radicals such as n-octyl and isooctyl such as 2,2,4-trimethylpentyl; nonyl radicals such as n- nonyl; decyl radicals such as n-decyl; dodecyl radicals such as n-dodecyl; octadecyl radicals such as n-octadecyl; cycloalkyl radicals such as cyclopentyl, cyclohexyl, cycloheptyl and methylcyclohexyl radicals; alkenyl radicals such as vinyl, 1-propenyl and 2-propenyl radicals; aryl radicals such as phenyl, naphthyl, anthryl and phenanthryl; alkaryl radicals such as o-, -, p- tolyl radicals, xylyl radicals and ethylphenyl radicals; and aralkyl radicals such as the benzyl, alpha-phenylethyl and beta-phenylethyl radicals.

[0058] Referring now to (ii), organosilicon compounds having Si-bonded hydrogen atoms are typically linear, cyclic or branched siloxanes consisting of units of the formula R⁴ _uH_vSiO₍₄__u- v_)/2 where R⁴ in each occurrence may be the same or different and may be the same as R³, u is 0, 1, 2 or 3, and v is 0, 1 or 2, typically 0 or 1, with the proviso that the sum total of u+v is not more than 3 and there are on average two or more Si-bonded hydrogen atoms per molecule. [0059] In various embodiments, (ii) includes three or more SiH bonds per molecule. In other embodiment wherein (ii) only has two SiH bonds per molecule, (i) typically includes at least three aliphatic carbon-carbon multiple bonds per molecule. In still other embodiments, (ii) has an Si-bonded hydrogen content of typically 0.002% to 1.7% by weight of hydrogen and more typically between 0.1 % and 1.7% by weight of hydrogen. In other embodiments, (ii) is present in an amount relative to (i) such that the molar ratio of SiH groups in (ii) to radicals having aliphatic carbon-carbon multiple bonding of (i) is between 0.5 and 5 and more typically between 1.0 and 3.0.

[0060] In any embodiment above, one or more fillers may be used. One or more fillers may be hydrophilic or hydrophobic and may include reinforcing fillers, non-reinforcing fillers, and/or combinations thereof. In one embodiment, a reinforcing filler is utilized. Non-limiting examples of reinforcing fillers include silica, titanium dioxide, ground quartz, calcium carbonate, alumino silicates, organosilicon resins. Fumed or precipitated silica fillers may also be used. Non-limiting examples of non-reinforcing fillers which can be employed are quartz flour, calcium silicate, zirconium silicate, zeolites, metal oxide powders, such as aluminum oxide, titanium oxide, iron oxide or zinc oxide, barium silicate, calcium carbonate and if appropriate calcium sulfate and barium sulfate when an inhibiting effect can be ruled out, and also polymeric powders, such as polyacrylonitrile powder or polytetrafluoroethylene powder. Additional fillers further include fibrous components, such as glass fibers and polymeric fibers.

[0061] In other embodiments, the filler is described as an oval or sphere- shaped solid and/or a laminar solid, which may be the same or different from one another. Suitable non-limiting spherical-oval solids may be selected from the group of the silicon oxides and metal oxides, organic compounds, organosilicon compounds, and combinations thereof. Oxides of the metals aluminum, titanium, zirconium, tantalum, tungsten, hafnium, zinc, and tin may be used. Colloidal silicas and precipitated silicas may also be used. Aluminas such as corundum, mixed aluminum oxides with other metals and/or silicon, titanias, zirconias, and iron oxides can also be used. Spherical fillers may have a diameter in from 0.01 to 100, from 1 to 40, or from 2 to 25 μιη.

[0062] The filler may include thin-walled hollow spheres or microcapsules providing the option of taking up a fluid, multilayered walling structures, core-shell structures, thick-walled hollow spheres or solid spheres having particle sizes in the nanometer or micrometer range, or combinations thereof. The filler may be inorganic, xenomorphous, hypidiomorphous, microcrystalline, cristallite like X-ray amorphous to amorphous or include mixed forms of different intergrowths/aggregations, and may be not only monophasic but also polyphasic. Spheres, microspheres or nanospheres of borosilicate glass, technical grade glass, Si0₂ glass, calcium carbonate or ceramic compositions, may also be utilized. The filler may be treated with functional silanes such as vinyltrialkoxysilanes, vinyltriacetoxysilanes, glycidoxypropyltrialkoxysilanes or methacryloyloxypropyltrialkoxysilanes. Non-limiting examples of additional organofunctional groups include acryloyl groups, epoxy groups, hydroxyl groups, and alkoxy groups.

[0063] Alternatively, polymeric organic particles or powders having particle sizes in the nanometer to micrometer range or mixtures thereof, such as vinyl acetate-ethylene copolymers, polyacrylonitrile powders, acrylates or styrene-acrylates, may be utilized. Spherical solid silicone resins, such as MQ resins, TD resins having glass transition points of around 30°C and/or silicone elastomers, which may also include functional groups, may also be used.

[0064] The filler may also include laminar solids selected from natural phyllosilicates such as mica or clay minerals including calcined variants, synthetic solids such as metal or glass flakes or platelet-shaped metal oxides/hydroxides or tectosilicates such as leaf zeolites, or combinations thereof. Non-limiting examples of natural phyllosilicates are three-layer silicates of the talc pyrophyllite group, the di- to trioctahedral three-layer silicates of the mica group such as muscovite, paragonite, phlogopite, and biotite, the four-layer silicates of the chlorite group and representatives of the clay mineral group, such as kaolinite, montmorillonite, and illite.

[0065] Laminar fillers may be partly untreated or surface treated with functional silanes, whereby a slight reinforcing effect can be achieved. Non-limiting examples of functional silanes with which the fillers can be surface treated are vinyltrialkoxysilanes, vinyltriacetoxysilanes, glycidoxypropyltrialkoxysilanes or methacryloyloxypropyltrialkoxysilanes. Mono-, di- and tetra- alkoxysilanes, which may bear organic functions in addition to the alkoxy function, may also be utilized.

[0066] Laminar solids, given sufficient delamination, are typically characterized in that their length is numerically greater than their thickness. Depending on whether they are natural sheet- silicates or the preferably calcined variants, the thickness is typically 10 to 20 times smaller than the length.

[0067] The filler may alternatively include a reinforcing filler combined with the laminar solid that has a high specific surface area >50 square meters per gram of the laminar solid (m²/g) or a high oil number >100. The filler may also include diverse nanoscale components such as aluminosilicates, calcium carbonate, and silicon dioxide. Non-limiting examples of reinforcing fillers are pyrogenic or precipitated silicas having Brunaur-Emmett-Teller (BET) surface areas of at least 50 m²/g, furnace black and acetylene black. Non-limiting examples of reinforcing solids possessing high oil absorption are diatomaceous earths, which can be used in calcined or preferably in natural form. The laminar and an additionally reinforcing solid can be present in weight ratios of 2: 1 and 1 :2, or in a ratio of 1 : 1, compared to one another.

[0068] In other embodiments, the surface of the filler is rendered hydrophobic to make the filler more compatible with the aforementioned components. Rendering the filler hydrophobic may be done either prior to or after dispersing the filler in, for example, (A), (I), or (i). This can be effected by pre-treatment of the filler with fatty acids, reactive silanes or reactive siloxanes. Non-limiting examples of suitable hydrophobing agents include stearic acid, dimethyldichlorosilane, divinyltetramethyl disilazane, trimethylchlorosilane, hexamethyldisilazane, hydroxyl end-blocked or methyl end-blocked polydimethylsiloxanes, siloxane resins or mixtures of two or more of these. Alternatively, the surface of the filler may be rendered hydrophobic in situ, that is, after the filler has been dispersed. Silicone resins may also be used as a filler, for example an MQ resin.

[0069] In one embodiment, (A), (I), and/or (i) and (B), (II), and/or (ii) are reacted in the presence of a filler chosen from a metallic filler, an inorganic filler, a meltable filler, and combinations thereof and wherein the filler is present in the product of a reaction between (A), (I), and/or (i) and (B), (II), and/or (ii), e.g. in the second outermost layer. In such an embodiment, the filler would then be present in the module and/or the second outermost layer. Alternatively, (A), (I), and/or (i) and (B), (II), and/or (ii) may be reacted in the presence of talc in an amount of from 2 to 70 weight percent based on a total weight of the second outermost layer. In another embodiment, (A), (I), and/or (i) and (B), (II), and/or (ii) are reacted together in the presence of titanium dioxide in an amount of up to about 30 or 35 weight percent based on a total weight of the second outermost layer wherein a total amount of titanium dioxide and optionally talc does not exceed about 45 weight percent. Throughout this disclosure, the combinations of components may describe both physical combinations of components and/or functional combinations of components. The "weight" of the second outermost layer can be determined by weighing all other components of the module before addition of the second outermost layer and then again after addition and determining the difference there between. Alternatively, the weight of the second outermost layer may be determined by weighing the components of the second outermost layer immediately prior to addition to one or more components of the module described above. For example, if the second outermost layer is formed from a composition, the weight of the composition may be utilized to determine the weight of the second outermost layer and may provide a basis for weights of one or more of the aforementioned components, compounds, or fillers, and the like. [0070] In various other embodiments, the second outermost layer may be described as being, including, consisting essentially of, or consisting of Wacker Elastosil^® 47007 and/or Shinetsu X- 32-2988 / CX-32-2988 coatings that may include kaolin, ethyl silicate and quartz as fillers. The terminology "consisting essentially of may describe that, in this embodiment, the second outermost layer is free of additional polymers, such as polyorganosiloxanes and/or organic polymers.

[0071] In another embodiment, the second outermost layer is, includes, consists essentially of, consists of, or is formed from, the following composition wherein the ratio of the Base to Curing Agent parts is 1 :3, 2:3, 3:3, 4:3, 5:3, 6:3, 7:3, 8:3, 9:3, or 10:3:

Base:

3 to 10 wt % alpha- Hydroxy-, omega- Methoxy-terminated Dimethyl, Methylvinyl Siloxane 15 to 30 wt % Hydroxy-terminated Dimethyl, Methylvinyl Siloxane

7 to 15 wt % Trimethyl terminated dimethyl, methylvinyl siloxane

8 to 15 wt Dimethylvinylsiloxy-terminated Dimethyl, Methylvinyl Siloxane

0.1 to 1 wt % Dimethylcyclosiloxanes

40 to 60 wt % Talc Magnesium Silicate

.007 to 1 wt l,3-Diethenyl-l,l,3,3,-tetramethyldisiloxane platinum complexes

Curing Agent:

0.1 to 1 wt Ethynyl Cyclohexanol

95 to 98 wt Hydroxy terminated poly(dimethylsiloxane)

2 to 5 wt Dimethylvinylsiloxy-terminated Dimethyl, Methylvinyl Siloxane

[0072] Any one of the aforementioned compositions or components may also include one or more additives and/or tie layers, and/or encapsulants, as described in U.S. Provisional Application entitled "Photovoltaic Cell Module" designated as Attorney Docket Number DC11520 PSP1, which is expressly incorporated by reference herein in its entirety in non- limiting embodiments.

Method of Formin2 the Photovoltaic Cell Module:

[0073] The present disclosure also provides a method of forming the module. The method includes the step of assembling the first outermost layer, the photovoltaic cell, the backsheet, and the second outermost layer to form the module. In one embodiment, the first outermost layer, the photovoltaic cell, and the backsheet are assembled together prior to assembly with the second outermost layer. For example, the second outermost layer may be installed on an existing module that is already assembled in the field. In another embodiment, the first outermost layer, the photovoltaic cell, the backsheet, and the second outermost layer are assembled simultaneously. In still another embodiment, the backsheet and the second outermost layer are assembled together prior to assembly with the first outermost layer or the first outermost layer and the photovoltaic cell.

[0074] The step of assembling may be further defined as contacting and/or compressing any one or more of the above with another. Even after the step of compressing, the photovoltaic cell and the first outermost layer do not need to be in direct contact with each other. The step of compressing may be further described as applying a vacuum, e.g. to the photovoltaic cell and the first outermost layer. Alternatively, a mechanical weight, press, or roller (e.g. a pinch roller) may be used for compression. The step of compressing may be further described as laminating the module and/or any one or more components described above. Still further, the method may include the step of applying heat to the module and/or any one or more components described above. Heat may be applied in combination with any other step of contacting and/or compressing or may be applied in a discrete step. Vacuum may be applied in combination with any other contact and/or compressing step or may be applied in a discrete step. The entire method may be continuous or batch-wise or may include a combination of continuous and batch-wise steps.

[0075] It is contemplated that the second outermost layer may be added to (e.g. contacted with) the backsheet before, simultaneously with, or after any one or more of the other layers or components are assembled. In one embodiment, the second outermost layer is applied to an existing module, e.g. already in use in the field. This may be described as retro-fitting an existing module with the second outermost layer.

[0076] Alternatively, the photovoltaic cell may be disposed directly on the backsheet via chemical vapor deposition or physical sputtering. In yet another embodiment, the photovoltaic cell is disposed directly on the first outermost layer via chemical vapor deposition or physical sputtering. The photovoltaic cell can be disposed (e.g. applied) by any suitable mechanism known in the art but is typically disposed using an applicator in a continuous mode. In one embodiment, the photovoltaic cell is disposed on the first outermost layer via chemical vapor deposition or physical sputtering. Other suitable mechanisms of disposing the photovoltaic cell on the first outermost layer include applying a force to the photovoltaic cell to more completely contact the photovoltaic cell and the first outermost layer.

[0077] Any of the aforementioned compositions of any component may be disposed using any suitable application method known in the art including, but not limited to, spray coating, flow coating, curtain coating, dip coating, extrusion coating, knife coating, screen coating, laminating, melting, pouring, brushing, and combinations thereof. In various embodiments, one or more silicone compositions are supplied as a multi-part system including a first and a second part. The first and second parts may be mixed immediately prior to application. In a further embodiment, the method further includes the step of partially curing, e.g. "pre-curing," any one or more of the aforementioned compositions.

[0078] In an additional embodiment, the method may include the step of treating the first outermost layer, the photovoltaic cell, the backsheet, and/or the second outermost layer with a plasma, e.g. as described in U.S. Pat. No. 6,793,759, incorporated herein by reference.

[0079] One or more of the values described above may vary by ± 5%, ± 10%, ± 15%, ± 20%, ± 25%, etc. so long as the variance remains within the scope of the disclosure. Unexpected results may be obtained from each member of a Markush group independent from all other members. Each member may be relied upon individually and or in combination and provides adequate support for specific embodiments within the scope of the appended claims. The subject matter of all combinations of independent and dependent claims, both singly and multiply dependent, in addition to all combinations of paragraphs and embodiments described therein, is herein expressly contemplated. The disclosure is illustrative including words of description rather than of limitation. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the disclosure may be practiced otherwise than as specifically described herein.

Claims

CLAIMS What is claimed is:

1. A photovoltaic cell module comprising:

A. a first outermost layer having a light transmittance of at least 70 percent as determined by UV/Vis spectrophotometry using ASTM E424-71 (2007);

B. a photovoltaic cell disposed on said first outermost layer;

C. a backsheet disposed on said photovoltaic cell; and

D. a second outermost layer opposite said first outermost layer, said second outermost layer disposed on an outward facing surface of said backsheet sandwiching said photovoltaic cell and said backsheet between said second outermost layer and said first outermost layer,

wherein said second outermost layer is present in a coating weight of from 3 to 75 grams per square meter of the outward facing surface of said backsheet,

wherein said backsheet comprises an organic polymer,

wherein said second outermost layer consists essentially of a silicone, and wherein said photovoltaic cell module passes the Wet Leakage Current Test at a voltage of at least 1000 Volts using IEC 61215 after humidity cycling for 1,000 hours.

2. The photovoltaic cell module of claim 1 wherein said silicone of said second outermost layer is a product of a reaction between:

(A) an organopolysiloxane having a degree of polymerization of less than or equal to 150 and terminated with at least two silicon-bonded R groups, wherein each R group is independently an olefinically unsaturated group, an alkoxy group, or a hydroxyl group; and

(B) a organosilicon cross-linker having at least 3 silicon-bonded groups reactive with one or more of said R groups; in the presence of

(C) an effective amount of a catalyst that catalyzes a reaction between (A) and (B) that forms the silicone of said second outermost layer.

3. The photovoltaic cell module of claim 2 wherein (A) and (B) are reacted in the presence of a filler chosen from a metallic filler, an inorganic filler, a meltable filler, and combinations thereof and wherein said second outermost layer further comprises said filler.

4. The photovoltaic module of claim 2 wherein (A) and (B) are reacted in the presence of talc in an amount of from 2 to 70 weight percent based on a total weight of said second outermost layer and wherein said silicone of said second outermost layer further comprises said talc.

5. The photovoltaic cell module of claim 2 or 4 wherein (A) and (B) are reacted together in the presence of titanium dioxide in an amount of up to about 30 weight percent based on a total weight of said second outermost layer wherein a total amount of titanium dioxide and optionally talc does not exceed 45 weight percent based on a total weight of said second outermost layer and wherein said silicone of said second outermost layer further comprises said titanium dioxide and optionally said talc.

6. The photovoltaic cell module of any one of claims 2 to 5 wherein said catalyst is a hydrosilylation catalyst and said silicone of said second outermost layer is a hydrosilylation product of a reaction between (A) and (B).

7. The photovoltaic cell module of any one of claims 2 to 5 wherein said silicone of said second outermost layer comprises a product of a reaction between (A) and (B).

8. The photovoltaic cell module of any one of claims 2 to 5 wherein (A) comprises 10 to 50 mole percent of vinylmethylsiloxane units based on a total number of moles of (A).

9. The photovoltaic cell module of any one of claims 2 to 5 wherein (A) comprises both silicon-bonded vinyl groups and silicon-bonded hydroxyl groups in a single molecule.

10. The photovoltaic cell of any preceding claim wherein said second outermost layer exhibits a coefficient of friction of 0.1 to 0.7 against itself measured according to ISO 8295.

11. A method of forming a photovoltaic cell module comprising a first outermost layer having a light transmittance of at least 70 percent as determined by UV/Vis spectrophotometry using ASTM E424-71 (2007), a photovoltaic cell disposed on the first outermost layer, a backsheet disposed on the photovoltaic cell, and a second outermost layer opposite the first outermost layer and disposed on an outward facing surface of the backsheet sandwiching the photovoltaic cell and the backsheet between the second outermost layer and the first outermost layer, wherein said second outermost layer is present in a coating weight of from 3 to 75 grams per square meter of the outward facing surface of said backsheet, wherein said backsheet comprises an organic polymer and said second outermost layer consists essentially of a silicone, and wherein said photovoltaic cell module passes the Wet Leakage Current Test at a voltage of at least 1000 Volts using IEC 61215 after humidity cycling for 1,000 hours, said method comprising the step of assembling the first outermost layer, the photovoltaic cell, the backsheet, and the second outermost layer to form the photovoltaic cell module.

12. The method of claim 11 wherein the first outermost layer, the photovoltaic cell, and the backsheet are assembled together prior to assembly with the second outermost layer.

13. The method of claim 11 wherein the first outermost layer, the photovoltaic cell, the backsheet, and the second outermost layer are assembled simultaneously.

14. The method of claim 11 wherein the backsheet and the second outermost layer are assembled together prior to assembly with the first outermost layer and the photovoltaic cell.

15. The method of any one of claims 11 to 14 wherein said the photovoltaic cell is disposed directly on the backsheet via chemical vapor deposition or physical sputtering.

16. The method of any one of claims 11 to 14 wherein said the photovoltaic cell is disposed directly on the first outermost layer via chemical vapor deposition or physical sputtering.