WO2018013618A1

WO2018013618A1 - Novel solar modules, supporting layer stacks and methods of fabricating thereof

Info

Publication number: WO2018013618A1
Application number: PCT/US2017/041610
Authority: WO
Inventors: Thomas G. Hood; Sicco Westra
Original assignee: Giga Solar Fpc, Inc.
Priority date: 2016-07-12
Filing date: 2017-07-12
Publication date: 2018-01-18

Abstract

A solar cell supporting layer stack for mechanically supporting a solar cell is described. The solar cell supporting layer stack including: two skin layers made from polypropylene thermoplastic including continuous glass fibers; a closed-cell, rigid foam layer disposed between the two skin layers and wherein the rigid foam layer is made from a cross-linked, thermally- stabilized polyvinylchloride foam; and two adhesive layers, each of which is disposed between the rigid foam layer and each of the two skin layers.

Description

NOVEL SOLAR MODULES, SUPPORTING LAYER STACKS AND METHODS OF FABRICATING

THEREOF

RELATED APPLICATION

[0001] This application claims priority from U.S. Provisional Application having Serial No. 62/361,490, filed on July 12, 2016, which is incorporated herein by reference for all purposes.

FIELD

[0002] The present teachings generally relate to novel solar modules, solar cell supporting layer stacks, solar cell performance layer stacks, and methods of fabricating thereof. More particularly, the present teachings relate to novel designs and methods of making solar modules, solar module supporting layer stacks and solar cell performance stacks that employ one or more foam layers and skin layers.

BACKGROUND

[0003] Solar photovoltaic modules (hereinafter also referred to as "solar modules") directly convert sunlight into electricity. During this process, however, solar modules are subject to demanding environmental conditions, including daily high levels of solar radiation, high and low temperatures, airborne particulates and chemicals, rain, ice, snow, hail, and high-speed winds. Conventional modules may use a combination of crystalline-silicon solar cells, a glass protective cover sheet, and an aluminum frame to protect against these conditions. Unfortunately, a combination of the solar module's weight and size makes them difficult for an individual to lift and limits the amount of modules that can be placed onto roofs of many buildings. The module weight, design and material choice also limits methods of shipping, and increases the installation cost on building roofs and other support structures.

[0004] What are, therefore, needed are novel designs of solar modules, solar module support structures, and solar cell performance layers that effectively function as an energy conversion apparatus, without suffering the drawbacks encountered by the heavy conventional solar modules. SUMMARY

[0005] It is the objective of this invention to improve the conventional, crystalline-silicon glass-frame module by reducing its weight while retaining all of the other heretofore-mentioned beneficial aspects, including: rigidity, low cost, high reliability, and ease of manufacture. In one aspect, the present arrangement provides a solar cell supporting layer stack for mechanically supporting a solar cell. The supporting layer stack includes: (i) two skin layers made from polypropylene thermoplastic including continuous glass fibers; (ii) a closed-cell, rigid foam layer, made from a cross-linked, thermally-stabilized polyvinyl chloride foam, disposed between the two skin layers; and (iii) two adhesive layer, each disposed between the rigid foam layer and each of the two skin layers.

[0006] In one embodiment of the present arrangements, the rigid foam layer is an interpenetrating polymer network of polyvinyl chloride and polyurea. In another embodiment of the present arrangements, the rigid foam layer has a thickness that ranges from about 1 mm to about 5 mm. In accordance with one embodiment of the present arrangements, the rigid foam layer has a density that ranges from about 60 kg/m³ to about 100 kg/m³. In certain embodiments of the present arrangements, the rigid foam layer may have sufficient load bearing properties to support the solar cells. By way of example, rigid foam layer has a compression strength that ranges from about 0.85 MPa to about 2.0 MPa. As another example, the rigid foam layer has a compression modulus that is between about 58 MPa and about 135 MPa. As yet another example, rigid foam layer has a shear strength that ranges from about 0.75 MPa to about 1.6 MPa. As yet another example, the rigid foam layer has a shear modulus that ranges from about 18 MPa to about 35 MPa.

[0007] The above-mentioned two skin layers preferably have a coefficient of thermal expansion that ranges from about 1 μιη /m°C to about 10 μηι /m°C and at least one of the two skin layers has a thickness that ranges from about 0.3 mm to about 1.0 mm. In another embodiment of the present arrangements, the continuous glass fiber, of at least one of the two skin layers, is made from at least one material selected from a group comprising E-glass, A- glass, E-CR-glass, C-glass, D-glass, R-glass, and S-glass, and the glass fibers in the continuous glass fibers extend in a same direction. [0008] Each skin layer may also have multiple layers of continuous glass fibers. Preferably, the skin layers include between 2 and 4 continuous glass fiber layers. In one embodiment of the present arrangements, at least one layer of continuous glass fiber is oriented in a direction that is different than another layer of continuous glass fiber. By way of example, one layer of glass fibers extends in a first direction and another layer of glass fibers extends in a second direction. The first direction and the second direction are at an angle that ranges from about 45 degrees to about 120 degrees. Preferably, at least one layer of continuous glass fiber is oriented 90 degrees in relation to another layer of continuous glass fiber.

[0009] In another embodiment of the present arrangements, the adhesive layers are made from at least one material selected from a group comprising ethylene vinyl acetate, thermoset polyolefin, and thermoplastic polyolefin. Preferably, each adhesive layer has a thickness that ranges from about 200 μηι to about 500 μηι.

[0010] In another aspect, the present arrangements provide a solar cell performance layer stack including: (i) a top cover made from at least one material selected from a group comprising ethylene chlorotrifluoroethylene (ECTFE), ethylene tetrafluoroethylene (ETFE), and

polyvinylidene fluoride (PVDF); (ii) a polycrystalline silicon or monocrystalline solar cell; and (iii) a first encapsulant layer and a second encapsulant layer. The first encapsulant and the second encapsulant layer, in one preferred embodiment of the present arrangements, are made of thermoset polyolefin. Preferably, the solar cell is disposed between and adjacent to the first encapsulant layer and the second encapsulant layer, and the top cover layer is adjacent to the first encapsulant layer.

[0011] In one embodiment of the present arrangements, the thickness of the top cover has a value that ranges from about 25 μηι to about 75 μηι and solar cell has a thickness that ranges from about 25 μηι to about 250 μηι. In another embodiment of the present arrangements, at least one of the first encapsulant and the second encapsulant has a thickness that ranges from about 300 μηι to about 600 μηι.

[0012] In yet another aspect, the present arrangements provide a rigid, lightweight solar module including: (i) a top cover; (ii) a silicon solar cell; (iii) a first encapsulant layer and a second encapsulant layer. The solar cell is disposed between the first encapsulant layer and the second encapsulant layer and the top cover layer is adjacent to the first encapsulant layer. The rigid, lightweight solar module also includes (iv) a solar cell supporting layer stack, for mechanically supporting the solar cell, adjacent to the second encapsulant layer. Preferably, the supporting layer stack includes: (v) two skin layers made from polypropylene thermoplastic with continuous glass fiber; (vi) a closed-cell, rigid foam layer, made from a cross-linked, thermally- stabilized polyvinylchloride foam, disposed between the two skin layers; and (vii) two adhesive layers, each of which is disposed between the rigid foam layer and the two skin layers.

[0013] In one embodiment of the present arrangements, the solar cell is made of

polycrystalline silicon or monocrystalline silicon and the top cover is made from at least one material selected from a group comprising glass, acrylic, ethylene chlorotrifluoroethylene (ECTFE), ethylene tetrafluoroethylene (ETFE) or polyvinylidene fluoride (PVDF). Preferably, the top cover has a thickness ranges from about 25 μηι to about 100 μηι.

[0014] In another embodiment of the present arrangements, the first encapsulant and/or the second encapsulant is made from at least one material selected from a group comprising ethylene vinyl acetate, thermoplastic polyolefin, and thermoset polyolefin. Preferably, the first encapsulant and second encapsulant is made from thermoset polyolefin. In yet another embodiment of the present arrangements, the first encapsulant and/or the second encapsulant has a thickness that ranges from about 300 μηι to about 600 μηι. Preferably, the two skin layers are of the same thickness.

[0015] In yet another aspect, the present invention provides a process for fabricating a solar cell supporting layer stack. The process includes: (i) obtaining a closed-cell, rigid foam layer made from a cross-linked, thermally-stabilized polyvinylchloride foam; (ii) obtaining two skin layers disposed adjacent to the rigid foam layer. Each skin layer is made from polypropylene resin with continuous glass fiber. Another step includes (iii) obtaining two adhesive layers disposed between the rigid foam layer and each of the two skin layers. Yet another step includes (iv) applying temperature and pressure to the outer surfaces of the two skin layers. In one embodiment of the present arrangements, the temperature applied to the two skin layers ranges from about 140°C to about 160°C and pressure applied to the two skin layer layers ranges about 0.8 atmosphere to about 1.0 atmosphere. Preferably, a double-sided, flatbed laminator with continuous heated metal belts applies temperature and pressure to the solar cell supporting layer stack.

[0016] In yet another aspect, the present invention provides a process for fabricating a rigid, lightweight solar module. The process includes: (i) obtaining a top cover; (ii) obtaining a solar cell; (iii) obtaining a first encapsulant layer and a second encapsulant layer. Preferably, the solar cell is disposed between and adjacent to the encapsulant layer and the second encapsulant layer and the top cover layer is adjacent to the first encapsulant layer. Another step includes (iv) obtaining a solar cell supporting layer stack that includes: (a) a closed-cell, rigid foam layer made from a cross-linked, thermally-stabilized polyvinylchloride foam; (b) obtaining two skin layers disposed adjacent to the rigid foam layer, wherein each of which is made from

polypropylene resin with continuous glass fiber; (c) two adhesive layers disposed between the rigid foam layer and each of the two skin layers. Another step (v) includes laminating, in a solar module lamination press, the top cover, solar cell, first and second encapsulant layers, and solar cell supporting layer stack to create a rigid, lightweight solar module.

[0017] The construction and process of manufacture of the invention, however, together with additional objects and advantages thereof, will be understood from the following descriptions of specific embodiments when read in connection with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS [0018] Figure 1 is an exploded side-sectional view of a solar module, according to one embodiment of the present arrangements, including an exemplar inventive solar cell supporting layer stack and performance layer stack.

[0019] Figure 2 shows an exploded side-sectional view of the solar module of Figure 1 undergoing manufacturing, according to one embodiment of the present arrangements.

DETAILED DESCRIPTION OF THE DRAWINGS

[0020] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without limitation to some or all of these specific details. In other instances, well-known process steps have not been described in detail in order to not unnecessarily obscure the invention.

[0021] The present teachings recognize that conventional crystalline-silicon solar module designs are inadequate to meet the market demands of modern solar modules- e.g., high conversion efficiency, lightweight, lower loads on roofs or support structures, long-lasting, easy to manufacture, ease of handling, ease of installation, and cost competitive. In sharp contrast, the present arrangements and teachings describe novel and unexpected combinations of materials that, when assembled in certain configurations, meet or exceed the photovoltaic industry performance testing standards as defined by the International Electrotechnical Commission (IEC), as well as, the highly-constrained economic parameters demanded of a solar module. Moreover, the present arrangements and teachings improve conventional crystalline-silicon glass-frame modules by reducing its weight and at the same time provide advantages of rigidity, low cost, high reliability and ease of manufacture.

[0022] Figure 1 shows a rigid, lightweight solar module 100, according to one embodiment of the present arrangements and that includes a solar cell performance layer stack 102 (hereafter also referred to as a "performance layer stack") coupled to a solar cell supporting layer stack 104 (hereafter also referred to as a "supporting layer stack"). Supporting layer stack 104 includes a closed-cell, rigid foam layer 106 sandwiched between two skin layers 108 and 110. Rigid foam layer 106 and skin layers 108 and 1 10 provide mechanical support to one or more solar cells 116 when the supporting layer stack is assembled with solar cells 116 within solar module 100.

Adhesive layer 112 and 114 couple rigid foam layer 104 to skins 108 and 110, respectively, to preferably hold supporting layer stack 104 together during the lifetime and operation of solar module 100.

[0023] Performance layer stack 102 includes one or more solar cells 116 coupled to and sandwiched between encapsulant layers 1 18 and 120. A top cover 122 is coupled to an exterior surface of encapsulant layer 118 and provides numerous functional and mechanical properties for solar module 100. By way of example, top cover 122 allows a high transmittance of the wavelengths used by solar cells 116 to produce electricity, experiences very little optical and physical degradation, and provides a mechanical barrier to ensure that environmental effects (e.g., rain, hail, and chemicals) do not negatively impact the solar module's performance over time. In addition, top cover 122 isolates solar cells 116 and conductors to prevent electrical injury to installers, maintenance and emergency personnel, is low weight, and is low cost. Top cover 122 includes materials that provide such exemplar benefits and may include one material selected from a group comprising glass, acrylics, and fluoropolymers. According to one preferred embodiment of the present teachings, top cover 122 is a fluoropolymer that may be at least one material selected from a group comprising ethylene chlorotrifluoroethylene

("ECTFE"), ethylene tetrafluoroethylene ("ETFE"), and polyviny dene fluoride ("PVDF"). [0024] The thickness of a fluoropolymer top layer 122, in accordance with one embodiment of the present arrangements, has a value that ranges from about 25 μηι to about 75 μηι. In a preferred embodiment of the present arrangements, fluoropolymer top layer 122 thickness has a value that ranges from about 25 μηι to about 35 μηι and, in a more preferred embodiment of the present arrangements, has a value that ranges from about 36μηι to about 45 μηι. In an even more preferred embodiment of the present arrangements, fluoropolymer top layer 122's thickness has a value that ranges from about 46 μηι to about 60 μηι. In another even more preferred embodiment of the present arrangements, fluoropolymer top layer 122's thickness has a value that ranges from about 61 μηι to about 75 μηι.

[0025] In an embodiment of the present arrangements that uses an acrylic for top cover 122, the thickness of acrylic top cover 122 has a value that ranges from about 0.075 mm to about 1.25 mm, and preferably ranges from about 0.075 mm to about 1.0 mm. In an even more preferred embodiment of the present arrangements, acrylic top cover 122's thickness has a value that ranges from about 0.076 to about 0.100 mm. In another even more preferred embodiment of the present arrangements, the thickness of acrylic top cover 122 has a value that ranges from about 0.101 mm to about 0.250 mm. In yet another more preferred embodiment of the present arrangements, acrylic top cover 122's thickness has a value that ranges from about 0.251 mm to about 0.500 mm. According to yet another preferred embodiment of the present arrangements, acrylic top cover 122's thickness has a value that ranges from about 0.501 mm to about 0.750 mm. Acrylic top cover 122, in yet another preferred embodiment of the present arrangements, has a thickness value that ranges from about 0.751 mm to about 1.0 mm and in yet another preferred embodiment ranges from about 1.001 mm to about 1.25 mm.

[0026] In an arrangement that includes a glass top cover 122, glass top cover 122's thickness has a value that ranges from about 0.10 mm to about 1.75 mm, and preferably has a value that ranges from about 0.10 mm to about 1.25 mm. In another embodiment of the present

arrangements, glass top cover 122's thickness has a value that ranges from about 0.10 mm to about 0.50 mm. In yet another embodiment of the present teachings, glass top cover 122's thickness has a value that ranges from about 0.51 mm to about 0.75 mm. Glass top cover 122's thickness, in yet another embodiment of the present teachings, has a value that ranges from about 0.76 mm to about 1.0 mm and in yet another embodiment has a value that ranges from about 1.01 mm to about 1.25 mm. In yet another embodiment of the present arrangements, glass top cover 122's thickness has a value that ranges from about 1.26 mm to about 1.5 mm. Further still, in yet another embodiment of the present arrangements, glass top cover 122's thickness has a value that ranges from about 1.51 mm to about 1.75 mm.

[0027] Coupled to top cover 122 is encapsulant 1 18. Both encapsulants 118 and 120 act as an adhesive and surround solar cells 116. Therefore, encapsulants 118 and 120 preferably have excellent adhesive properties to effectively encapsulate solar cells 116, as well as any metallic materials used for the electrical connections. To this end, encapsulants 1 18 and 120 may also have dielectric properties that insulate solar cells 1 16 and/or the electrical connections.

Additionally, encapsulants 118 and 120 preferably maintain a low water vapor transmission rate to limit moisture ingress through encapsulant 118 and 120.

[0028] Similar to top cover 122, encapsulant 118 preferably has a high transmittance of solar wavelengths. By way of example, solar ultraviolet energy between about 300 nanometer wavelengths and about 400 nanometer wavelengths can generate electricity from solar cells 1 16. Therefore, in one embodiment of the present arrangements, ultraviolet energy between about 300 nanometer wavelengths and about 400 nanometer wavelengths is capable of being transmitted through encapsulant 118. However, it may not be desirable for encapsulant 120 to have the same transmittance characteristics. Ultraviolet energy may damage certain material types (e.g., polymeric materials). By way of example, ultraviolet energy transmitted though encapsulant 120 and absorbed by adjacent skin 108 may accelerate degradation of skin 108 and/or weaken the bond strength between encapsulant 120 and skin 108. To that end, encapsulant 120, in one embodiment of the present arrangements, does not transmit high quantities of ultraviolet through encapsulant 120 to skin 108. As a result, it is optimum to have high ultraviolet energy

transmission in encapsulant 118 but low ultraviolet energy transmission in encapsulant 120.

[0029] Furthermore, encapsulants 118 and 120, as will be discussed in greater detail below in regard to the manufacturing process, may be bonded to both top cover 122 and to skin layer 108 of supporting layer stack 104. Thus, encapsulants 118 and 120 preferably form a strong bond to a broad range of materials while also being exposed to solar ultraviolet energy, temperature variances, and changing environmental conditions.

[0030] To achieve these desired bonding properties and improve performance characteristics, conventional encapsulants use a thermoset polymer (i.e. , a cross-linked plastic). By way of example, conventional encapsulants may use thermoset ethylene vinyl acetate ("EVA"). EVA encapsulants, however, are inadequate for the present arrangements because they may lower the performance of a solar module over time. To establish cross-linking, conventional thermoset encapsulants include a chemical catalyst. By way of example, commonly used catalysts for EVA encapsulants are organic peroxides. Chemical cross-linking improves the performance characteristics and better stabilizes the encapsulating materials. However, during the laminating process, the chemical catalyst may not cause all of the thermoset encapsulant to cross-link, leaving uncross-linked polymer material.

[0031] During the lifespan of a solar module, uncross-linked polymer material may combine with solvents (e.g., water) to form an acid. If EVA is used as an encapsulant, uncross-linked vinyl-acetate monomers may combine with solvents (e.g., water) to form acetic acid. EVA has a high moisture vapor transmission rate that allows moisture to penetrate the encapsulants, assisting acid formation. Acetic acid may cause a yellowing or darkening of encapsulant 118 and 120, which prevents transmission of solar energy to solar cells 116, reducing the efficiency of solar cells 116. Acetic acid can also corrode the metallization that is present on solar cells 1 16, increasing electrical resistance and lowering solar cell performance.

[0032] To overcome the limitations of conventional encapsulants, in one embodiment of the present arrangements, encapsulants 118 and 120 are made from a thermoplastic polymer, which does not include a chemical catalyst. By way of example, encapsulants 1 18 and 120, in one embodiment of the present arrangements, is made from thermoplastic poly olefin, which does not use a catalyst or produce acid over time. In another preferred embodiment of the present arrangements, encapsulants 118 and 120 are made from thermoset poly olefin. Thermoset polyolefin encapsulants, which is cross-linked via a catalyst, may provide higher resistance to long-term creep at elevated temperatures than thermoplastic polyolefin, and thus can be useful in applications where creep is a concern, such as a vertical or high-sloped application on a building wall or roof, respectively. Moreover, neither thermoset nor thermoplastic polyolefins create acetic, or other, acid as a result of the presence of moisture, UV, and/or elevated temperature.

[0033] Thermoset and thermoplastic polyolefin may also exhibit lower water absorption and moisture vapor transmission rates than EVA, and thus provide greater moisture protection. A conventional solar module includes additional non-polymeric barrier layers (e.g., a glass cover layer) that, along with conventional encapsulants, protect the solar cells from moisture. The present arrangements, however, may not include additional non-polymeric moisture barrier layers. Thus, the encapsulants used in the present arrangements, are able to adequately protect the solar cells from moisture without additional moisture barrier layers.

[0034] In one embodiment of the present arrangements, the thickness of encapsulants 118 and 120 has a value that ranges from about 300 μηι to about 600 μιτι, and preferably has a value that ranges from about 300 μηι to about 550 μηι. In another embodiment of the present arrangements, encapsulant 1 18 and 120's thickness has a value that ranges from about 300 μηι to about 350 μηι. In yet another embodiment, encapsulant 118 and 120's thickness has a value that ranges from about 351 μηι and about 400 μηι. In yet another embodiment of the present arrangements, encapsulant 1 18 and 120's thickness has a value that ranges from about 401 μηι to about 450 μηι. In yet another embodiment of the present arrangements, encapsulant 118 and 120's thickness has a value that ranges from about 451 μηι to about 500 μηι. In yet another embodiment of the present arrangements, encapsulant 118 and 120's thickness has a value that ranges from about 501 μηι to about 550 μηι. In yet another embodiment of the present arrangements, encapsulant 1 18 and 120's thickness has a value that ranges from about 551 μηι to about 600 μηι.

[0035] Solar cells 116, encapsulants 1 18 and 120, and top cover 122, which constitute performance layer stack 102, protects solar cells from environmental conditions while allowing solar cells 1 16 to simultaneously receive solar energy. Performance layer stack 102 contributes a certain amount of mechanical stiffness of solar module 100. However, a novel combination of layers (e.g., rigid foam layer 106, skin layers 108 and 110, and adhesive layers 112 and 114) and materials in supporting layer stack 104, according to the present arrangements, provides the stiffness and rigidity required of solar module 100 while also protecting solar cells 1 16 from environmental elements. In addition to stiffness and rigidity, supporting layer stack 104 is low weight, easy to manufacture, low cost, and durable. In other words, supporting layer stack 104 offers a solution to the unique and demanding requirements for producing a commercially viable, long-lasting, economic, and lightweight rigid solar module 100. This has not been successfully demonstrated in the conventional designs of solar modules and related layer stacks.

[0036] Skin layers 108 and 1 10, according to one embodiment of the present arrangements, provide stiffness to supporting layer stack 104. To that end, skin layers 108 and 110 preferably have excellent physical properties, including: tensile and compressive moduli and strength across a broad temperature range. Skin layers 108 and 110 should exhibit isotropic properties in the plane of the material, with compressive and shear moduli greater than about 20 GPa and compressive and shear strengths greater than about 200 MPa. In an assembled configuration, when supporting layer stack 104 is adjacent to performance layer stack 102, mechanical attributes of skin layers 108 and 110 minimize deflection of the solar module 100 under load, reducing the chance of breakage of solar cells 116.

[0037] In addition to providing stiffness, skin layers 108 and 1 10 provide thermal stability to the supporting layer stack 104. Thermal stability, as measured by a coefficient of thermal expansion, of skin layers 108 and 1 10 limit the expansion and contraction of supporting layer stack 104. During the manufacturing process and during an operative state of solar module 100, solar module 100 undergoes significant temperature changes. By way of example, during the manufacturing process solar module 100 may experiences temperatures that range from about 140°C to about 160°C. Beyond manufacturing, the in-service stresses on each of the module's components will vary as the temperature of solar module 100 cycles from hot to cold. Depending on the geographic location of solar module 100, the annual temperature extremes may range from about -40°C to about 100°C. In one embodiment of the present arrangements, skin layers 108 and 110 have a coefficient of thermal expansion that is between about 1 μιη /m°C and about 10 nm /m⁰C.

[0038] The present arrangements preferably provide skin layers 108 and 110 capable of providing stiffness and thermal stability for solar module 100. In one embodiment of the present arrangements, skin layers 108 and 110 are a polymer matrix and fiber composite. Preferably, the polymer has material properties (e.g., high impact and bend strength, stiff, high compressive and tensile properties, hydrolytic stability, thermal stability, low flammability, high bond strength to fibers, low cost and recyclability) that, in combination with fibers, protects solar module 100 during manufacturing and during operation. In one embodiment of the present arrangements, the polymer used in skins 108 and 110 includes at least one material comprising polyethylene, polypropylene, and polyamide. In a preferred embodiment of the present arrangement, skin layers 108 and 1 10 are made of thermoplastic polypropylene.

[0039] In one embodiment of the present arrangements, fibers in skin layers 108 and 110 include at least one material selected from group comprising glass, aramid, and carbon.

Preferably, the fiber being used in skin layer 108 and 110 is a glass fiber. To that end, glass fibers include at least one material selected from a group comprising E-glass, A-glass (Alkali- lime glass with little or no boron oxide), E-CR-glass (Electrical/Chemical Resistance glass - alumino-lime silicate with less than 1% alkali oxides, with high acid resistance), C-glass (alkali- lime glass with high boron oxide content), D-glass (borosilicate glass), R-glass (alumino silicate glass without MgO and CaO), and S-glass (alumino silicate glass without CaO but with high MgO content). In one preferred embodiment of the present arrangements, E-glass fiber is used because as it provides corrosion resistance, strength and dielectric properties, and is relatively inexpensive.

[0040] In another embodiment of the present arrangements, the percentage of glass fiber in skin layers 108 and 1 10 ranges from about 40% glass fiber by weight to about 90% glass fiber by weight. The remaining weight of skin layers 108 and 110 is polymer material. In a preferred embodiment of the present arrangements, the percentage of glass fiber in skin layers 108 and 110 ranges from about 50% glass fiber by weight to about 90% glass fiber by weight. In a more preferred embodiment of the present arrangements, the percentage of glass fiber in skin layers 108 and 110 ranges from about 60% glass fiber by weight to about 70% glass fiber by weight.

[0041] The fiber in a polymer-fiber skin may be of any orientation. In a preferred embodiment of the present arrangements, however, skins 108 and 1 10 include continuous fibers - unbroken, linear fibers that extend in the same direction - that are unidirectionally embedded into a polymer. Used in combination with a thermoplastic polymer (e.g., a thermoplastic polypropylene) the continuous fibers create a continuous fiber reinforced thermal plastic. Skin layers 108 and 110 having continuous fiber reinforced thermal plastic are strong, lightweight, inexpensive, and provide advantageous mechanical properties.

[0042] Skin layers 108 and 110 may also incorporate multiple layers of continuous fiber reinforced thermal plastic, wherein each layer of continuous fiber reinforced thermal plastic are bonded to each other by thermal welding. Furthermore, each continuous fiber reinforced thermal plastic layer may extend in a direction that is different than another continuous fiber layer. By way of example, a direction of a first continuous fiber reinforced thermal plastic layer and a direction of second continuous fiber reinforced thermal plastic layer may be at an angle that ranges from about 45 degree to about 90 degree. In a preferred embodiment of the present arrangements, the direction of first continuous fiber reinforced thermal plastic layer is oriented 90 degree in relation to the second continuous fiber reinforced thermal plastic. This orthogonal configuration creates a 0/90 bi-directional skin layers 108 and 1 10. Furthermore, orthogonal skin layers 108 and 110 also insure uniform thermal and mechanical properties in an x and y direction of skin layers 108 and 1 10 wherein the x-direction refers to a horizontal direction and the y- direction is orthogonal to it. By way of example, adjacent orthogonal skin layers ensure that orthogonal skin layer 108 and orthogonal skin layer 110 has a uniform coefficient of thermal expansion. Thus, a temperature-generated dimensional change is uniform across skin layers 108 and 110. In other words, expansion and/or contraction of skin layers 108 and 100 are

substantially similar in the x and y directions.

[0043] If necessary, additional continuous fiber reinforced thermal plastic layers can be added to form a 0/90/0 construction, or a 90/0/90 construction. In a 0/90/0 configuration, according to one embodiment of the present arrangements, a first and third continuous fiber reinforced thermal plastic layer are oriented 0 degrees in relation to the x-direction and sandwich a second continuous fiber reinforced thermal plastic layer, which is oriented 90 degrees in relation to the first and third continuous fiber reinforced thermal plastic layers. In a 90/0/90 configuration, according to another embodiment to the present arrangements, the first and third continuous fiber reinforced thermal plastic layer are oriented in the same direction {i.e., 90 degrees in relation to the x-direction) and sandwich the second continuous fiber reinforced thermal plastic layer, which is oriented 0 degrees in relation to the first and third continuous fiber reinforced thermal plastic layers.

[0044] Each additional layer improves the strength and rigidity of skin layer 108 and 110, but also increases the cost and weight. In a preferred embodiment of the present arrangements, skin layers 108 and 1 10 include between 2 and 4 continuous fiber reinforced thermal plastic layers and is more preferably between 2 or 3 continuous fiber reinforced thermal plastic layers. Skin layers 108 and 1 10 may be of different thicknesses and even different polymer types, however, to ensure balanced thermal properties during the manufacturing process and during operation, skin layers 108 and 1 10 of similar thickness and/or polymer type may assist in maintaining a flat composite.

[0045] In one embodiment of the present arrangements, the thickness of skin layers 108 and 110 has a value that ranges from about 0.3 mm to about 1.0 mm, and is preferably from about 0.3 mm to 0.9 mm. In another embodiment of the present arrangements, the thickness of skin layers 108 and 1 10 has a value that ranges from about 0.3 mm and to 0.375 mm. In yet another embodiment of the present arrangements, the thickness of skin layers 108 and 110 has a value that ranges from about 0.376 mm to about 0.450 mm. In yet another embodiment of the present arrangements, the thickness of skin layers 108 and 1 10 has a value that ranges from about 0.451 mm to about 0.525 mm. In yet another embodiment of the present arrangements, the thickness of skin layers 108 and 110 has a value that ranges from about 0.526 mm to about 0.60 mm. In yet another embodiment of the present arrangements, the thickness of skin layers 108 and 1 10 has a value that ranges from about 0.601 mm to about 0.675 mm. In yet another embodiment of the present arrangements, the thickness of skin layers 108 and 1 10 has a value that ranges from about 0.676 mm to about 0.75 mm. In yet another embodiment of the present arrangements, the thickness of skin layers 108 and 110 has a value that ranges from about 0.751 mm to about 0.825 mm. In yet another embodiment of the present arrangements, the thickness of skin layer 108 and 110 has a value that ranges from about 0.826 mm to about 0.90 mm. In yet another embodiment of the present arrangements, the thickness of skin layers 108 and 110 has a value that ranges from about 0.901 mm to about 1.0 mm.

[0046] Rigid foam layer 106 provides a lightweight spacer between skin layers 108 and 110. The separation distance between skin layer 108 and 1 10 is an important feature in determining the overall stiffness of supporting layer stack 104, and thus, of the solar module 100. In addition to contributing to the stiffness of solar module 100, rigid foam layer 106 preferably endures solar module 100 manufacturing conditions (e.g., about 140°C to about 160°C and 1 atmosphere pressure) without physical or chemical degradation. Furthermore, rigid foam layer 106 preferably meets a 25-year life span requirement as a component of solar module 100.

[0047] Rigid foam layer 106, in one embodiment of the present arrangements, is a closed-cell, rigid foam, which has a higher dimensional stability, greater uniformity, absorbs less moisture and exhibits higher strength than open-cell foam. In one embodiment of the present arrangements, the amount of cells that are in a closed-cell configuration has a value that ranges from between about 95% to about 99.99%. The remaining configuration of foam layer 106 is open and/or partially closed cells. In another embodiment of the present arrangements, the amount of cells that are in a closed-cell configuration has a value that ranges from about 95% to about 96%. In yet another embodiment of the present arrangements, the amount of cells that are in a closed-cell configuration has a value that ranges from about 96% to about 97%. In yet another embodiment of the present arrangements, the amount of cells that are in a closed-cell configuration has a value that ranges from about 97% and about 98%. In yet another embodiment of the present arrangements, the amount of cells that are in a closed-cell configuration has a value that ranges from about 98% to about 99%. In one preferred embodiment of the present arrangements, the amount of cells that are in a closed-cell configuration has a value that ranges from about 99% and about 99.99%.

[0048] In another embodiment of the present arrangements, rigid foam layer 106 is made from closed-cell polyethylene terephthalate (i.e., polyester) or closed-cell, cross-linked, thermally stabilized polyvinyl chloride (hereafter also referred to a "thermally stabilized PVC"). Thermally stabilized PVC foam layer 106 is an interpenetrating polymer network of PVC and polyurea that is cross-linked and thermally stabilized. Cross-linking increases the glass transition temperature, T_g, and significantly increases the heat resistant performance of the material. During the manufacturing process, polyvinyl chloride and polyurea are mixed together under controlled conditions. To cross-link the PVC, a mixture of polyvinyl chloride and polyurea is dispensed into a mold, which is placed into a large press and heated. After, a cross-linked slab of solid PVC emerges the mold. The cross-linked PVC then undergoes exposure to additional heat in order to expand it to a final density and to impart thermal stability. Such a product is commercially available from Diab International AB, Sweden and has a product designation of DIVINYCELL® HP. In one preferred embodiment of the present arrangements, cross-linked PVC may be subjected to processing temperatures as high as up to 90°C and in a more preferred embodiment to processing temperatures as high as 145^oC.

[0049] Unlike conventional PVC foam, a closed-cell, rigid foam layer made of thermally stabilized PVC is capable of withstanding temperature and humidity conditions encountered during manufacturing, testing, and while the solar module is in use. By way of example and as explained below regarding testing, a solar module made with a layer of rigid, thermally stabilized PVC foam successfully competed a damp heat test, which is 85°C and 85% relative humidity for 1,000 hours. Conventional PVC foam, however, may degrade when exposed to high temperatures and humidity and are impractical for use in a solar module support structure.

[0050] The density of rigid foam layer 106 in supporting layer stack 104 may be any value that provides solar module 100 with the requisite strength to withstand any undue external force. Rigid foam layer 106 density may be any value that ranges from about 60 kg/m³ to 100 kg/m³, and preferably from about 60 kg/m³ to about 80 kg/m³. In one embodiment of the present arrangements, the rigid foam density 106 may be any value that ranges from about 61 kg/m³ to about 65kg/m³, in another embodiment from about 66 kg/m³ to about 70 kg/m³. In yet another embodiment the density of rigid foam layer 106 may be any value that ranges from about 71 kg/m³ and to 75 kg/m³. In yet another embodiment of the present arrangements, the density of rigid foam layer 106 may be any value that ranges from about 76 kg/m³ to about 80 kg/m³.

[0051] Rigid foam layer may be of any suitable thickness that provides the requisite mechanical support to solar module 100. In accordance with one embodiment of the present arrangements, the thickness of rigid foam layer 106 in supporting layer stack 104 is a value that ranges from about 1 mm to 5 mm and more preferably is a value that ranges from about 2 mm to about 4 mm. In another embodiment of the present arrangements, the thickness of rigid foam layer 106 is a value that ranges from about 1.0 mm to about 1.5 mm. In yet another embodiment of the present arrangements, the thickness of rigid foam layer 106 is a value that ranges from about 1.6 mm and about 2.0 mm. In yet another embodiment of the present arrangements, rigid foam layer 106's thickness has a value that ranges from about 2.0 mm to about 2.5 mm. In yet another embodiment of the present arrangements, rigid foam layer 106's thickness has a value that ranges from about 2.6 mm and about 3.5 mm. In yet another embodiment of the present arrangements, rigid foam layer 106's thickness has a value that ranges from about 3.6 mm to about 4.0 mm. In yet another embodiment of the present arrangements, rigid foam layer 106's thickness has a value that ranges from about 4.1 mm to about 4.5 mm. In yet another embodiment of the present arrangements, rigid foam layer 106's thickness has a value that ranges from about 4.6mm and about 5.0 mm.

[0052] In certain embodiments of the present arrangements, it is desirable to have a rigid foam layer 106 that has sufficient load bearing properties that it can provide the rigidity and shear strength needed to address the static and dynamic forces that the solar module will see in application. To this end, a measurement of shear strength value of a foam layer in the inventive supporting layer stacks may be deemed relevant by those skilled in the art. In those instances when this value is so deemed, shear strength was determined to have a value that ranges from about 0.75 MPa to about 1.6 MPa, and preferably from about 0.85 MPa to about 1.6 MPa. In one embodiment of the present arrangements, rigid foam layer 106's shear strength has a value that ranges from about 0.85 MPa to about 1.0 MPa. In yet another embodiment of the present arrangements, rigid foam layer 106's shear strength has a value that ranges from about 1.1 MPa to about 1.15 MPa. In yet another embodiment of the present arrangements, rigid foam layer 106's shear strength has a value that ranges from about 1.16 MPa to about 1.30 MPa. In yet another embodiment of the present arrangements, rigid foam layer 106's shear strength has a value that ranges from about 1.31 MPa to about 1.45 MPa. In yet another embodiment of the present arrangements, rigid foam layer 106's shear strength has a value that ranges from about 1.46 MPa to about 1.60 MPa.

[0053] In other instances, a shear modulus value of the inventive rigid foam layer 106 is an important measure of foam layer strength. In such instances, a shear modulus has a value that ranges from about 18 MPa to about 35 MPa, and preferably from about 19 MPa to about 35 MPa. In one embodiment of the present arrangements, rigid foam layer 106's shear modulus has a value that ranges from about 19 MPa to about 23 MPa. In yet another embodiment of the present arrangements, rigid foam layer 106's shear modulus has a value that ranges from about 24 MPa to about 27 MPa. In yet another embodiment of the present arrangements, rigid foam layer 106's shear modulus has a value that ranges from about 28 MPa to about 31 MPa. In yet another embodiment of the present arrangements, rigid foam layer 106's shear modulus has a value that ranges from about 32 MPa to about 35 MPa.

[0054] Rigid foam layer 106 may have a compressive strength value that may range from about 0.85 to 2.0 MPa, and may preferably range from about 0.95 MPa to about 2.0 MPa. In one embodiment of the present arrangements, rigid foam layer 106 has a compressive strength has a value that ranges from about 0.95 MPa to about 1.2 MPa. In another embodiment of the present arrangements, rigid foam layer 106 has a compressive strength value that ranges from about 1.21 MPa and about 1.35 MPa. In yet another embodiment of the present arrangements, rigid foam layer 106's compressive strength value has a range from between about 1.36 MPa and about 1.5 MPa. In yet another embodiment of the present arrangements, rigid foam layer 106's compressive strength value has a range from about 1.51 MPa to about 1.65 MPa. In yet another embodiment of the present arrangements, rigid foam layer 106 has a compressive strength value that ranges from about 1.66 MPa to about 1.8 MPa. In one embodiment of the present arrangements, rigid foam layer 106's compressive strength value has a range from about 1.81 MPa and about 2.0 MPa.

[0055] To the extent that a shear modulus value is deemed a relevant measure of physical properties of rigid foam layer 106, the present teachings contemplates a range of measurements. By way of example, rigid foam layer 106 has a compressive modulus value that ranges from about 58 to about 135 MPa, and preferably ranges from about 65 MPa to about 135 MPa. In yet another embodiment of the present arrangements, the compressive modulus of rigid foam layer 106 has a value that ranges that is about 65 MPa to about 80 MPa. In yet another embodiment of the present arrangements, the compressive modulus of rigid foam layer 106 has a value that ranges from about 80 MPa to about 95 MPa. In yet another embodiment of the present arrangements, the compressive modulus of rigid foam layer 106 has a value that ranges from about 95 MPa to about 110 MPa. In yet another embodiment of the present arrangements, the compressive modulus of rigid foam layer 106 has a value that ranges from about 110 MPa to about 125 MPa. In yet another embodiment of the present arrangements, the compressive modulus of rigid foam layer 106 has a value that ranges from about 125 MPa to about 135 MPa.

[0056] Adhesive layers 112 and 114 bond skin layers 108 and 110, respectively, to rigid foam layer 106. This bond is long lasting and strong enough to withstand a range of temperatures for the life span of solar module 100. In one embodiment of the present arrangements, adhesive layers 1 12 and 1 14 include at least one material selected from a group comprising ethylene vinyl acetate (EVA), polyolefin elastomers ("POE") (i.e., cross-linked or thermoset polyolefin), and thermoplastic polyolefin ("TPO"). Each of these materials does not require modification of the bonding surfaces to improve bond performance.

[0057] EVA and POE are thermoset polymers, and thus, rely on a catalyst to initiate cross- linking. The activation of this catalyst requires a minimum temperature and minimum cure time to ensure adequate cross-linking. Thus, specialized equipment and processing are needed to adequately crosslink the adhesive layer 1 12 and 1 14. Thermoplastic adhesives, however, such as thermoplastic polyolefin do not require a minimum cure time, only a certain temperature minimum. This simpler processing procedure eliminates specialized equipment and increases manufacturing speed, which reduces costs. As a result, in preferred embodiments of the present arrangements, adhesive layers 112 and 1 14 are a thermoplastic polyolefin.

[0058] Regardless of material selection, adhesive layers 1 12 and 114 are relatively inexpensive and lend themselves to simple application during the manufacturing process of supporting layer stack 104 or solar module 100. Unlike the encapsulant layers 118 and 120, which also act as an adhesive layer, adhesive layers 112 and 1 14 do not require excellent optical properties as they are laminated between opaque skins layers 108 and 110 and thus, their optical properties do not determine the module performance. In one preferred embodiment of the present arrangements, adhesives 112 and 114 are the same material.

[0059] In one embodiment of the present arrangements, the thickness of each of adhesive layer 1 12 and adhesive layer 1 14 has a value that ranges from about 200 μηι to about 450 μηι. In another embodiment of the present arrangements, the thickness of each of adhesive layers 1 12 and adhesive layer 1 14 has a value that ranges from about 200 μηι to about 250 μηι. In yet another embodiment of the present arrangements, the thickness of each of adhesive layers 1 12 and adhesive layer 1 14 has a value that ranges from about 251 μηι and about 300 μηι. In yet another embodiment of the present arrangements, the thickness of each of adhesive layer 1 12 and adhesive layer 114 has a value that range from about 301 μηι and about 350 μηι. In yet another embodiment of the present arrangements, the thickness of each of adhesive layer 1 12 and adhesive layer 114 has a value that range from about 351 μηι to about 400 μηι. In yet another embodiment of the present arrangements, the thickness of each of adhesive layer 1 12 and adhesive 114 has a value that range from about 401 μηι to about 450 μηι. In yet another embodiment of the present arrangements, the thickness of each of adhesive layer 1 12 and adhesive layer 114 has a value that range from about 451 μηι and about 500 μηι.

[0060] The present arrangements, through the use of a novel performance layer stack 102 and supporting layer stack 104, substantially reduces the weight of a conventional solar modules (e.g., glass-frame crystalline-silicon modules). Table 1 shows weight reduction between solar module 100 and a conventional solar module for two standard solar module sizes - a 60-cell module and a 72-cell module. The conventional solar module and solar module 100 have the same width and length for a given power level. A 60-cell solar module 100 weighs 58% less than a conventional glass-frame solar module and a 72-cell solar module 100 weighs 57% less than a conventional glass-frame solar module. This significant weight reduction provides numerous benefits to the solar industry. By way of example, a reduced weight of over 50% reduces shipping costs, allows a greater quantity of solar modules 100 to be transported on weight constrained shipping methods (e.g., boat, truck, and plates), simplifies maneuverability during installation (e.g., raising and lowering solar modules onto rooftops), and reduces the expensive solar module mounting and installation. Module Weight Weight

Number Module

Module Type Power Reduction Reduction of Cells Weight (kg)

(watts) (kg) (%)

Glass-Frame 60 275 19.6 - -

Solar Module 60 275 7.5 10.5 58%

100

Glass-Frame 72 340 21.6 - -

Solar Module 72 340 9.3 12.3 57%

100

TABLE 1

[0061] The following tests 1 through test 5 provide independent laboratory testing of solar module 100 containing forty -two solar cells 116. Each test provides one or more accelerated stress tests to evaluate the characteristics of solar module 100. Furthermore, each test conforms to test standard IEC 61215 (entitled "Crystalline silicon terrestrial photovoltaic (PV) modules - Design qualifications and type approval"), which is recognized in the solar PV industry. IEC 6125 provides test procedures for tests 2-5 described below. Solar modules 100 that were subjected to this testing was constructed using the materials shown in Table 2.

Adhesive 1 12 450 μιη Cross-linked ethylene vinyl acetate

Rigid Foam 106 3.2 mm PVC with density of 80 kg/m³

Adhesive 1 14 450 μιη Cross-linked ethylene vinyl acetate

Skin 110 0.65 mm Glass-polypropylene, 3-layer sheet

TABLE 2

[0062] Test 1 - The robustness test. The robustness tests measured panel stiffness (i.e., resistance to bending under load) and localized pressure loading. These tests were designed to simulate the handling stresses of solar module 100 during installation. In particular, the test examined solar cell cracking as a result of forces on solar module 100, which may a reduce the power output of solar module 100. Cell cracking was examined using an electroluminescent system that non-destructively detects poorly contacted and inactive regions of each solar cell, including micro-cracks. The power loss measures a difference in power output of solar module 100 before and after the robustness test to determine if there was a reduction in solar module 100 power output.

[0063] Robustness testing was performed using two test procedures. The first procedure involved the application of a load uniformly applied onto the module's surface and measuring the deflection. The amount of the load to be applied was determined by the weight of the module and then doubled. The uniform load of 5.5 kg (i.e., twice the weight of solar module 100) was applied on 42-cell solar module 100 resulted in a maximum deflection of about 3 mm and about 5mm depending on the location of where the deflection was measured. In addition, 50 temperature cycles from between about -40°C and about +85°C were applied to the module after stressing and no cell cracking or power loss was observed. These results suggest that the rigidity of this lightweight module is sufficient for handling, shipping and installation without fear of damaging the fragile solar cells.

[0064] The second test procedure involved the application of a concentrated load onto a small area of the module, from the front surface. This procedure was performed to simulate the potential dead load onto a cell from a person standing on the module. The load was about 91 kg and the load area was 446 cm², resulting in a load of about 0.2 kg/cm². The load was static and left for about 1 minute and repeated 4 times. These samples were, subsequent to the localized pressure test, temperature cycled 50 times and then measured for power loss and inspected via electroluminescence for cracks. There were no cracks observed and the power loss was than about 0.3% from the measured pre-test power to the post-test power. These results confirmed the mechanical integrity of the lightweight module for real world conditions.

[0065] Example 2 - The damp-heat test. Per IEC-61215 test procedures, five solar modules 100 samples underwent test conditions of 85°C and 85% relative humidity ("85/85 test") for 1,000 hours. A successful completion of the damp-heat test (a "Pass") requires less than a 5% change from the initial power to the final (post- test) power. As shown in Table 3, each solar module 100 had a power reduction of less than 5% and passed the damp-heat test. Solar module 100 sample 5 of Table 3 was subsequently subjected to an additional 1000 hours of 85/85 damp heat conditions. As shown in Table 4, solar module 100 sample 5 again passed the damp-heat test. The ability of solar module 100, having a polymeric construction and without edge seal, to pass 2,000 hours of 85/85 damp heat testing is a surprising and unanticipated result. Heretofore solar modules that are primarily constructed of only polymeric components have required costly designs using materials with extremely low moisture vapor transmission rate (i.e., metal films, exotic polymers, or thick mastics designed as moisture barriers) to prevent the 85/85 condition from negatively affecting the module's performance. The test data provide results that are comparable or superior to modules made from glass.

TABLE 3

5 177.3 177.0 -1.6% Pass

TABLE 4

[0066] Test 3 - The thermal cycle test. Solar module 100, per IEC-61215 test procedures, are temperature cycling from about -40°C to about +85°C for 200 cycles. A successful completion of the thermal cycle test, per IEC-61215 instructions, requires less than 5% change from the initial power to the final (post- test) power. As shown in Table 5, each solar module 100 sample completed, and passed, the thermal cycling test. Each sample did not illustrate degradation in power.

TABLE 5

[0067] Test 4 - The humidity/freeze test. Four samples of solar module 100 where tested per IEC-61215. Test conditions are temperature cycling from about -40°C to about +85°C with 85% relative humidity when the temperature is above approximately 25°C, for 10 cycles. A successful completion of the humidity/freeze test requires less than a 5% change from the initial power to the final (post-test) power. Table 6 shows that all for samples of solar module 100 a change in power output that was significantly less than the 5% requirement to pass the humidity/freeze test and, thus, passed.

TABLE 6 [0068] Test 5 - The hail impact test. The hail impact test involves the impact of ice balls of a specific size and at a specific speed as defined by IEC-61215. For this test, an ice ball with a diameter of about 25 mm and an ice ball velocity of about 23 meters per second were used. The test requires that eleven ice balls impact the module at prescribed locations. The power change is measured from before and after the impacts. A successful completion of the hail impact test requires less than a 5% change from the initial power to the final (post-test) power. As shown in Table 7, four samples of solar module 100 passed the hail impact test. It was unanticipated that the construction of solar module 100 would perform well in hail impact testing, given that top cover 122 is a 50-μηι thick fluoropolymer film. A fluoropolymer of this thickness is capable of flexing and does not provide a very high level of impact absorption, and, on its own, may not protect the solar cells from the impact of ice balls. Surprisingly, the modules performed very well and easily met the "less than 5% power loss" criteria. The highly rigid support provided by the supporting layer stack 104 creates a composite with excellent impact strength that prevented damage to the solar cells.

TABLE 7

Solar module 100 samples subjected to the hail test were subsequently exposed to 50 thermal- cycles from between about -40°C and bout +85°C to assess whether solar cells that were cracked by the ice-ball impact continued to degrade with expansion and contraction of the module. No further degradation was observed. All IEC 61215 tests performed require that there is no evidence of major visual defects as well. This requirement was met by all of the modules tested as described in Tables 2 through 7, above. [0069] The present teachings also offer novel processes of fabricating solar module 100 and components therein. By way of example, the present invention provides novel processes of fabricating skin layers 108 and 110. In one embodiment of the present inventions, each layer of continuous fiber reinforced thermal plastic is fabricated in continuous rolls, referred to as "tapes." Tape rolls may be manufactured with widths that range from about 150 mm to about 250 mm. An exemplar solar module 100 has a width that ranges from about 950 mm to about 1000 mm. The process of fabricating wide format roles of continuous fiber reinforced thermal plastic includes obtaining two or more, continuous fiber reinforced thermal plastic tapes. Another step includes placing each continuous fiber reinforced thermal plastic tape side by side such the edge of one continuous fiber reinforced thermal plastic tape is adjacent to an edge of another continuous fiber reinforced thermal plastic tapes. Another step includes thermally bonding the edges together to form wide format roles of continuous fiber reinforced thermal plastic. If skin layer 108 and 1 10 include multiple additional layers of glass fibers, an additional step includes bonding a first layer of wide format continuous fiber reinforced thermal plastic to another first layer of wide format continuous fiber reinforced thermal plastic.

[0070] Producing skin layers 108 and 110 in wide, long rolls, according to one embodiment of the present teachings, significantly reduces composite manufacturing complexity and cost, making glass-polymer materials viable for use in low-cost, large-area applications such as solar modules. Furthermore, continuous glass-polymer materials allow continuous, or semi-continuous manufacturing processes. Adhesive layers 112 and 1 14 may be similarly manufactured in long rolls. Thus, the continuous bonding of the skins 108 and 110 and adhesives 112 and 114 to rigid foam layer 106 may be practically implemented, yielding a high-performance, low-cost composite for solar module applications.

[0071] The present teachings also provide novel process for manufacturing supporting layer stack 104. The process of fabricating supporting layer stack 104 includes obtaining a closed-cell, rigid foam layer made from a cross-linked, thermally-stabilized polyvinylchloride foam, obtaining two skin layers disposed adjacent to the rigid foam layer, wherein each of which is made from polypropylene resin with continuous glass fiber, obtaining two adhesive layers disposed between the rigid foam layer and each of the two skin layers. Another step includes applying temperature and pressure to an outer surface of the two skin layers. Preferably, the temperature applied to supporting layer stack is between about 140°C and about 180°C and the pressure is between about 1 atmosphere ("ATM") and about 4 ATM.

[0072] Fabrication of supporting layer stack 104 allows for semi-continuous or continuous solar module fabrication. By way of example, a flat-bed lamination system may be used to simultaneously, and continuously couple the skin layers 108 and 110 to rigid foam layer 106 using adhesive layers 1 12 and 1 14. The line speed of the laminator used to fabricate supporting layer stack is dependent on the length of the laminator and the time it takes adhesive layer 1 12 and 114 to bond to each of skin layers 108 and 1 10 to rigid foam layer 106. Unlike conventional thermoset adhesives (e.g., EVA and POE), which require temperature, pressure and a dwell time that ranges from about 8 minutes to about 10 minutes to crosslink, preferred thermoplastic adhesive layers 112 and 1 14 (e.g., TPO) only need a temperature and pressure to melt. Removal of dwell time as a process requirement allows for the increase of the temperature and line speed at which supporting layer stack 104 may be manufactured. Faster production speeds result directly in lower cost.

[0073] The present teachings also offer novel process of manufacturing novel solar module 100. The process of fabricating solar module 100 includes obtaining supporting layer stack (e.g., supporting layer stack 104 of Figure 1). Preferably, the supporting layer stack includes two skin layers made from polypropylene thermoplastic including continuous E-glass fibers, a closed-cell, rigid foam layer made from a cross-linked, thermally-stabilized polyvinyl chloride foam, and thermoplastic polyolefin adhesive layers. Next, the manufacturing process includes obtaining sections a performance layer stack (e.g., performance layer stack 102 of Figure 1). In one preferred embodiment of the present invention, obtaining the performance layer stack includes obtaining a fluoropolymer top cover, thermoset polyolefin encapsulants, and monocrystalline or polycrystalline solar cells.

[0074] Then, a laminating step may be carried out. Figure 2 shows a solar module 200, which is substantially similar to solar module 100 of Figure 1 , undergoing the lamination step. Performance layer stack 202, supporting layer stack 204, rigid foam layer 206, skin layer 208 and 210, adhesive layers 212 and 214, solar cells 216, encapsulant layers 218 and 220, and top cover 222 are substantially similar to performance layer stack 102, supporting layer stack 104, rigid foam layer 106, skin layer 108 and 110, adhesive layers 112 and 1 14, solar cells 116, encapsulant layers 1 18 and 120, and top cover 122 of Figure 1. This step includes laminating the supporting layer stack 104 and the sections of the performance layer stack 102 together with heat and pressure to create a solar module. During this laminating step, the temperature preferably ranges from about 140°C to 160°C and the pressure ranges from about 0.8 ATM to about 1.0 ATM. When solar module 200 undergoes a pressurized state, vacuum bag 226, which surrounds solar module 200 compresses the layers of solar module 200 together. Further, the encapsulants 218 and 220 surround the solar cells 216 - i.e., encapsulants 218 and 220 melt, flow around the solar cells and fuse together. In addition, encapsulant 218 adheres to the top cover 222 and encapsulant 220 adheres to a skin layer 208 of the supporting layer stack 204. Preferably, both layers of encapsulant are dry, film-based {i.e., not liquid) materials to lower the cost of solar module production. To ensure chemical compatibility both encapsulant layers may be made of the same basic chemistry, and preferably consist of the same material and from the same supplier.

[0075] As shown in Figure 2, the top cover 222 is placed adjacent to a glass support structure 224, which acts as a support providing a flat, rigid surface. Glass support structure 224 provides uniform thermal mass and thermal conductivity across its entire surface allowing solar module to be uniformly heated and/or cooled. This allows for relatively accurate control of the temperature rise and cooling during the manufacturing process.

[0076] Next, the solar module undergoes cooling to ensure a high quality final module lamination. In this step, the solar module is pressurized, however, the pressure may be less than the pressure in the laminating step. Preferably, the pressure ranges from about 0.5 ATM and about 1.0 ATM. The temperature of the pressurized solar module is reduced from temperatures achieved in the laminating step to a temperature that ranges from about 30°C to about 50°C. After lamination, a junction box is attached to the solar module.

[0077] Another novel process of manufacturing novel solar module includes obtaining the components of a supporting layer stack {e.g., supporting layer stack 104 of Figure 1). In one preferred embodiment of the present invention, obtaining the supporting layer stack includes obtaining two skin layers made from polypropylene thermoplastic including continuous E-glass fibers, closed-cell, rigid foam layer made from a cross-linked, thermally-stabilized polyvinyl chloride foam, and two thermoplastic polyolefin adhesive layers.

[0078] A next step includes obtaining the components of a performance layer stack {e.g., performance layer stack 102 of Figure 1). In one preferred embodiment of the present invention, obtaining the performance layer stack includes obtaining a fluoropolymer top cover, thermoset polyolefin encapsulants, and monocrystalline or polycrystalline silicon solar cells.

[0079] Next, the laminating and cooling steps are performed, which are substantially similar to steps described above. In one preferred embodiment of the present teachings, during the laminating step, a double-sided lamination system, which includes two heating surfaces to heat two sides of the solar module, is used. By way of example, glass support structure 124 heats top cover 212 and another heating surface heats skin layer 110. Thus embodiments of the present invention, the two heating surfaces melt adhesives 212 and 214 and encapsulants 218 and 220.

[0080] Although illustrative embodiments of this invention have been shown and described, other modifications, changes, and substitutions are intended. By way of example, the present invention discloses heat bonding a foam layer and at least one skin layer without using any adhesive, other conventional layers in the solar module may be similarly bonded. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure, as set forth in the following claims.

Claims

CLAIMS What is claimed is:

1. A solar cell supporting layer stack for mechanically supporting a solar cell, said solar cell supporting layer stack comprising:

two skin layers made of a polymer matrix and fiber composite, wherein said polymer includes at least one material selected from a group comprising polyethylene, polypropylene, and polyamide and wherein said fiber is a continuous glass fiber;

a closed-cell, rigid foam layer disposed between said two skin layers, wherein said rigid foam layer is made from polyethylene terephthalate or cross-linked, thermally-stabilized polyvinyl chloride; and

two adhesive layers, each of which adheres one of said two skin layers to said rigid foam layer.

2. The solar cell supporting layer stack of claim 1 , wherein said cross-linked, thermally - stabilized, polyvinyl chloride is an interpenetrating polymer network of polyvinyl chloride and polyurea.

3. The supporting layer stack of claim 1, wherein said rigid foam layer has a thickness that ranges from about 1 mm to about 5 mm.

4. The solar cell supporting layer stack of claim 1, wherein said rigid foam layer has a density ranges from about 60 kg/m³ to about 100 kg/m³.

5. The supporting layer stack of claim 1, wherein said rigid foam layer has a compression strength that ranges from about 0.85 MPa to about 2.0 MPa.

6. The solar cell supporting layer stack of claim 1, wherein said rigid foam layer has a compression modulus that ranges from about 58 MPa to about 135 MPa.

7. The solar cell supporting layer stack of claim 1, wherein said rigid foam layer has a shear strength that ranges from about 0.75 MPa to about 1.6 MPa.

8. The solar cell supporting layer stack of claim 1, wherein said rigid foam layer has a shear modulus that ranges from about 18 MPa and about 35 MPa.

9. The solar cell supporting layer stack of claim 1 , wherein said two skin layers are made from thermoplastic polypropylene including continuous glass fibers.

10. The solar cell supporting layer stack of claim 1, wherein said two skin layers have a coefficient of thermal expansion that ranges from about 1 μιη /m°C and about 10 μηι /m°C.

11. The solar cell supporting layer stack of claim 1, wherein at least one of said two skin layers has a thickness that ranges from about 0.3 mm and about 1.0 mm.

12. The solar cell supporting layer stack of claim 1, wherein said continuous glass fiber, of at least one of said two skin layers, is made from at least one material selected from a group comprising E-glass, A-glass, E-CR-glass, C-glass, D-glass, R-glass, and S-glass, and said glass fibers in said continuous glass fibers extend in a same direction.

13. The solar cell supporting layer stack of claim 1, wherein said continuous glass fiber, of said two skin layers, is made from E-glass.

14. The solar cell supporting layer stack of claim 1, wherein at least one of said two skin layers includes multiple layers of continuous glass fiber and at least one layer of continuous glass fiber is oriented in a direction that is different than another layer of continuous glass fiber.

15. The solar cell supporting layer stack of claim 12, wherein at least one of said two skins layers includes between 2 and 4 continuous glass fiber layers.

16. The solar cell supporting layer stack of claim 12, wherein said multiple layers of said continuous glass fibers, include one layer of glass fibers extending in a first direction and another layer of glass fibers extending in a second direction, and wherein said first direction and said second direction are at an angel that ranges from about 45 degrees to about 120 degrees.

17. The solar cell supporting layer stack of claim 14, wherein said at least one layer of continuous glass fiber is oriented 90 degrees in relation to said another layer of continuous glass fiber.

18. The solar cell supporting layer stack of claim 1, wherein said two adhesive layers are made from at least one material selected from a group comprising ethylene vinyl acetate, thermoset polyolefin, and thermoplastic polyolefin.

19. The solar cell supporting layer stack of claim 1, wherein each of said two adhesive layers has a thickness that ranges from about 200 μηι to about 500 μηι.

20. A solar cell performance layer stack comprising:

a top cover made from at least one material selected from a group comprising ethylene chlorotrifluoroethylene (ECTFE), ethylene tetrafluoroethylene (ETFE), and polyvinylidene fluoride (PVDF); a polycrystalline silicon or monocrystalline solar cell;

a first encapsulant layer and a second encapsulant layer, wherein said first encapsulant and said second encapsulant are made from thermoset poly olefin, wherein said solar cell is disposed between said first encapsulant layer and said second encapsulant layer, and wherein said top cover layer is adjacent to said first encapsulant layer.

21. The solar cell performance layer stack of claim 17, wherein the thickness of said top cover ranges from about 25 μηι to about 75 μηι.

22. The solar cell performance layer stack of claim 17, wherein said solar cell has a thickness that ranges from about 25 μηι and about 250 μηι.

23. The solar cell performance layer stack of claim 17, wherein said at least one of said first encapsulant and said second encapsulant has a thickness that ranges from about 300 μηι and about 600 μηι.

24. A rigid, lightweight solar module, said PV module comprising:

a top cover;

a silicon solar cell;

a first encapsulant layer and a second encapsulant layer, wherein said solar cell is disposed between said first encapsulant layer and said second encapsulant layer and wherein said top cover layer is adjacent to said first encapsulant layer; and

a solar cell supporting layer stack, for mechanically supporting said solar cell, adjacent to said second encapsulant layer, said supporting layer stack comprising:

two skin layers made from polypropylene thermoplastic with continuous glass fiber;

a closed-cell, rigid foam layer disposed between said two skin layers and wherein said rigid foam layer is made from a cross-linked, thermally-stabilized polyvinylchloride foam;

two adhesive layers, each of which adheres said rigid foam layer to one of said two skin layers.

25. The solar module of claim 13, wherein said solar cell includes polycrystalline silicon or monocrystalline silicon.

26. The solar module of claim 13, wherein said top cover is made from at least one material selected from a group comprising glass, acrylic, ethylene chlorotrifluoroethylene (ECTFE), and ethylene tetrafluoroethylene (ETFE) or polyvinylidene fluoride (PVDF).

27. The solar module of claim 13, wherein said at least one of said first encapsulant layer and said second encapsulant layer are made from at least one material selected from a group comprising ethylene vinyl acetate, thermoplastic polyolefin, and thermoset poly olefin.

28. The solar module of claim 13, wherein said at least one of said first encapsulant layer and said second encapsulant layer are made from thermoset polyolefin.

29. The solar module of claim 13, wherein said two skin layers are of the same thickness.

30. A process for fabricating a solar cell supporting layer stack, said process comprising:

obtaining a closed-cell, rigid foam layer made from a cross-linked, thermally- stabilized polyvinylchloride foam;

obtaining two skin layers disposed adjacent to said rigid foam layer, wherein each of which is made from polypropylene resin with continuous glass fiber;

obtaining two adhesive layers, each of which is disposed between said rigid foam layer and each of said two skin layers; and

applying temperature and pressure to an outer surfaces of said two skin layer.

31. The process of claim 22, wherein said temperature applied to said two skin has a value that ranges from about 140°C to about 160°C.

32. The process of claim 22, wherein said pressure has a value that ranges from about 0.8 atmosphere to about 1.0 atmosphere.

33. The process of claim 22, wherein a double-sided, flatbed laminator with continuous heated metal belts applies said temperature and pressure solar cell supporting layer stack.

34. A process of fabricating a rigid, lightweight solar module, said process comprising: obtaining a top cover;

obtaining a solar cell;

obtaining a first encapsulant layer and a second encapsulant layer, wherein said solar cell is disposed between and adjacent to said first encapsulant layer and said second encapsulant layer and wherein said top cover layer is adjacent to said first encapsulant layer;

obtaining a solar cell supporting layer stack, said comprising:

a closed-cell, rigid foam layer made from a cross-linked, thermally-stabilized polyvinylchloride foam;

two skin layers disposed adjacent to said rigid foam layer, wherein each of which is made from polypropylene resin with continuous glass fiber; and two adhesive layers, each of which is disposed between said rigid foam layer and each of said two skin layers; and

laminating said top cover, solar cell, said first and second encapsulant layers, and solar cell supporting layer stack in a solar module lamination press to create a rigid, lightweight solar module.

35. The process of fabricating said rigid, lightweight solar module of claim 32, further comprising cooling said rigid, lightweight solar module under pressure.

36. The process of fabricating said rigid, lightweight solar module of claim 33, where said pressure applied to said rigid, lightweight solar module ranges from about 0.5 atmosphere to about 1.0 atmosphere.