Patent Application
20140150862
The present invention relates to back contact photovoltaic modules, and more particularly to integrated back-sheets and encapsulant assemblies for making back contact photovoltaic modules, and to processes for making back-contact photovoltaic modules with such integrated back-sheet and encapsulant assemblies.
A photovoltaic cell converts radiant energy, such as sunlight, into electrical energy. In practice, multiple photovoltaic cells are electrically connected together in series or in parallel and are protected within a photovoltaic module or solar module.
A photovoltaic module typically comprises, in order, a light-transmitting substrate or front sheet, an encapsulant layer, an active photovoltaic cell layer, another encapsulant layer and a back-sheet. The light-transmitting substrate is typically glass or a durable light-transmitting polymer film. The encapsulant layers adhere the photovoltaic cell layer to the front and back sheets and they seal and protect the photovoltaic cells from moisture and air and they protect the photovoltaic cells against physical damage. The encapsulant layers are typically comprised of a thermoplastic or thermosetting resin such as ethylene-vinyl acetate copolymer (EVA). The photovoltaic cell layer is any type of photovoltaic cell that converts sunlight to electric current such as single crystal silicon solar cells, polycrystalline silicon solar cells, microcrystal silicon solar cells, amorphous silicon-based solar cells, copper indium (gallium) diselenide solar cells, cadmium telluride solar cells, compound semiconductor solar cells, dye sensitized solar cells, and the like. The back-sheet provides structural support for the module, it electrically insulates the module, and it helps to protect the solar cells, module wiring and other components against the elements, including heat, water vapor, oxygen and UV radiation. The module layers need to remain intact and adhered for the service life of the photovoltaic module, which may extend for multiple decades.
Photovoltaic cells have had electrical contacts on both the front and back sides of the photovoltaic cells. However, contacts on the front sunlight receiving side of the photovoltaic cells can cause up to a 10% shading loss. In back contact photovoltaic cells, all of the electrical contacts are moved to the back side of the photovoltaic cell. With both the positive and negative polarity electrical contacts on the back side of the photovoltaic cells, electrical circuitry is needed to provide electrical connections to the positive and negative polarity electrical contacts on the back of the photovoltaic cells.
In a back contact photovoltaic module, an integrated back-sheet having patterned electrical circuitry is electrically connected to back contacts on the photovoltaic cells during lamination of the solar module. A back-sheet 10 is shown in
Aligning the openings of the ILD and encapsulant layers with electrically conductive circuits, inserting the electrically conductive adhesive into the aligned openings, and then aligning the openings of the back-contact solar cells with the openings in the encapsulant and ILD layers has been difficult to accomplish, especially when the solar cells that are hand placed on the back-sheet. Expansion or contraction of the encapsulant layer prior to module lamination has further complicated the electrical contact alignment with the openings in the encapsulant and ILD layers. There is a need for back-contact photovoltaic modules with integrated electrically conductive circuitry that can be produced more efficiently and consistently.
An assembly for forming a back-contact photovoltaic module is provided. The assembly includes a substrate having aback surface and an opposite front surface, and an electrically conductive metal circuit adhered to the front surface of the substrate. A back insulating layer having first and second opposite sides is provided with the first side of the back insulating layer adhered to the electrically conductive metal circuit. The back insulating layer has a plurality of openings passing through the back insulating layer and that are aligned with the electrically conductive metal circuit.
The assembly includes a back-contact solar cell with a front light-receiving side, an opposite back side with a plurality of electrical contacts formed on the back side of said back-contact solar cell. The back side of the solar cell faces the back insulating layer. The back-contact solar cell has a side edge between the front side and back side of the solar cell that defines a profile of the solar cell.
The assembly includes a front encapsulant layer having opposite first and second sides, with first side of the front encapsulant layer facing the light-receiving front side of the back-contact solar cell. A transparent front sheet abuts the second side of the front encapsulant layer.
In the assembly, at least one of the second side of the back insulating layer and the first side of the front encapsulant layer has a concave opening formed thereon that complements the profile of the back-contact solar cell such that the back-contact solar cell fits into the concave opening. When the back-contact solar cell is received in the concave opening, the electrical contacts on the back side of the back-contact solar cell align with the openings passing through the back insulating layer and with the electrically conductive metal circuit.
A process for forming the described assembly for forming a back-contact photovoltaic module is also provided.
The detailed description will refer to the following drawings which are not drawn to scale and wherein like numerals refer to like elements:
a-1c are plan views of a conventional integrated back sheet assembly for a back-contact photovoltaic module;
d shows the position of back-contact solar cells placed over the back sheet assembly of
a and 3b are cross-sectional views showing steps in the formation of the disclosed integrated back-sheet for back-contact photovoltaic modules.
To the extent permitted by the applicable patent law, all publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.
The materials, methods, and examples herein are illustrative only and the scope of the present invention should be judged only by the claims.
The following definitions are used herein to further define and describe the disclosure.
As used herein, the terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).
As used herein, the terms “a” and “an” include the concepts of “at least one” and “one or more than one”.
Unless stated otherwise, all percentages, parts, ratios, etc., are by weight.
When the term “about” is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to.
As used herein, the terms “sheet”, “layer” and “film” are used in their broad sense interchangeably. A “frontsheet” is a sheet, layer or film on the side of a photovoltaic module that faces a light source and may also be described as an incident layer. Because of its location, it is generally desirable that the frontsheet has high transparency to the desired incident light. A “back-sheet” is a sheet, layer or film on the side of a photovoltaic module that faces away from a light source, and is generally opaque. In some instances, it may be desirable to receive light from both sides of a device (e.g., a bifacial device), in which case a module may have transparent layers on both sides of the device.
“Encapsulant” layers are used to encase the fragile voltage-generating photoactive layer, to protect it from environmental or physical damage, and hold it in place in the photovoltaic module. Encapsulant layers may be positioned between the solar cell layer and the front incident layer, between the solar cell layer and the back-sheet, or both. Suitable polymer materials for the encapsulant layers typically possess a combination of characteristics such as high transparency, high impact resistance, high penetration resistance, high moisture resistance, good ultraviolet (UV) light resistance, good long term thermal stability, good long term weatherability, and adequate adhesion strength to frontsheets, back-sheets, other rigid polymeric sheets and solar cell surfaces.
As used herein, the terms “photoactive” and “photovoltaic” may be used interchangeably and refer to the property of converting radiant energy (e.g., light) into electric energy.
As used herein, the terms “photovoltaic cell” or “photoactive cell” or “solar cell” mean an electronic device that converts radiant energy (e.g., light) into an electrical signal. A photovoltaic cell includes a photoactive material layer that may be an organic or inorganic semiconductor material that is capable of absorbing radiant energy and converting it into electrical energy. The terms “photovoltaic cell” or “photoactive cell” or “solar cell” are used herein to include photovoltaic cells with any types of photoactive layers including, crystalline silicon, polycrystalline silicon, microcrystal silicon, and amorphous silicon-based solar cells, copper indium (gallium) diselenide solar cells, cadmium telluride solar cells, compound semiconductor solar cells, dye sensitized solar cells, and the like.
As used herein, the term “photovoltaic module” or “solar module” or “solar cell module” (also “module” for short) means an electronic device having at least one photovoltaic cell protected on one side by a light transmitting front sheet and protected on the opposite side by an electrically insulating protective back-sheet.
As used herein, terms “die-cut” and “die-cutting” refer to a manufacturing process wherein one or more blades of a desired shape slice through one or more layers of a material such as wood, plastic, paper, metal or fabric to produce cut shapes of material, and includes die-cutting done on flat, rotary or multiple-step presses, as well as die-cutting by laser.
Disclosed herein is an integrated back-sheet and assembly for a back-contact photovoltaic module, processes for forming such an assembly, back-contact photovoltaic modules made with such an integrated back-sheet and assembly, and processes for forming such back-contact photovoltaic modules.
The disclosed integrated back-sheet includes a substrate. The substrate has a back surface and a front surface, wherein the front surface faces to the light source when in in use. The substrate may be comprised of inorganic materials, organic materials, or combinations of inorganic and organic materials. Suitable inorganic materials that may be used in forming the substrate include, without limitation, metallic materials (such as aluminium foil, aluminium panel, copper, steel, alloy, stainless steel, etc.), non-metallic inorganic materials (such as amorphous materials (e.g., glass) and crystalline materials (e.g., quartz)), inorganic compounds, ceramics, and minerals (such as mica or asbestos). Preferably, the substrate is comprised of polymeric materials, optionally in conjunction with other materials used in photovoltaic back-sheets. The substrate may comprise a polymer film, sheet or laminate that is used as a back-sheet in conventional photovoltaic modules. The substrate may, for example, be comprised of film comprised of one or more of polyester, fluoropolymer, polycarbonate, polypropylene, polyethylene, cyclic polyloefin, acrylic, cellulose acetate, acrylate polymer such as polymethylmethacrylate (PMMA), polystyrene, styrene-acrylate copolymers, acrylonitrile-styrene copolymers, poly(ethylene naphthalate), polyethersulfone, polysulfone, polyamide, epoxy resin, glass fiber reinforced polymer, carbon fiber reinforced polymer, vinyl chloride polymers, polyvinylidene chloride, vinylidene chloride copolymers, and the like. The substrate of the integrated back-sheet may also comprise laminates of such polymer films. The layers of such laminates may be adhered to each other by adhesives between the layers or by adhesives incorporated into one or more of the laminate layers.
Laminates of polyester films and fluoropolymer are especially suitable for the substrate. Suitable polyesters include polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polyethylene phthalate, polytrimethylene phthalate, polybutylene phthalate, polyhexamethylene phthalate or a copolymer or blend of two or more of the above. Suitable fluoropolymers include polyvinylfluoride (PVF), polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymers and combinations thereof. In one embodiment, the substrate comprises a bi-axially oriented PET film adhered to a PVF film. In another embodiment, the substrate comprises polyester film with fluoropolymer films adhered to the opposite sides of the polyester film. Alternatively, the substrate may comprise a single layer polymer sheet such as a synthetic rubber or polyolefin-based sheet.
There are no specific restrictions on the thickness of the substrate or on the various layers of the substrate. Thickness varies according to specific application. In one preferred embodiment, the substrate comprises a fluoropolymer layer with a thickness in the range of 20-50 μm adhered to a PET film with a thickness of 50-300 μm.
Various known additives and fillers may be added to the layer(s) of the substrate to satisfy various different requirements. Suitable additives may include, for example, light stabilizers, UV stabilizers and absorbers, thermal stabilizers, anti-hydrolytic agents, light reflection agents, flame retardants, pigments, titanium dioxide, dyes, slip agents, calcium carbonate, silica, and reinforcement additives such as glass fibers and the like. There are no specific restrictions to the content of the additives and fillers in the substrate layers as long as the additives do not produce an undue adverse impact on the substrate layers or their adhesion to other layers of the substrate or to the adhesion of the substrate to the electrically conductive metal circuit.
The polymeric films or sheets of the substrate may include one or more non-polymeric layers or coatings such as a metallic, metal oxide or non-metal oxide surface coating. Such coatings are helpful for reducing moisture vapor transmission through a back-sheet structure. The thickness of such a metallic, metal oxide layer or non-metal oxide layer on one or more of the polymer films typically measures between 50 Å and 4000 Å, and more typically between 100 Å and 1000 Å, but may be up to 50 um thick.
In the embodiment shown in
The disclosed integrated back-sheet further includes an electrically conductive metal circuit adhered to the substrate. The electrically conductive metal circuit may be any type of circuit such as a printed metal circuit or a circuit formed from a metal foil adhered to the substrate and etched, die-cut or otherwise formed into one or more patterned electrically conductive circuits. Where the electrically conductive metal circuit is formed from a metal foil, the foil is preferably an electrically conductive metal foil such as foil of aluminum, tin, copper, nickel, silver, gold, tin coated copper, silver coated copper, gold coated copper, steel, invar, and alloys thereof. Aluminum foil and copper foil are most commonly selected on the basis of cost and other factors. The thickness of the foil may be in the range of 5-50 μm, or preferably 8-40 μm. Examples of suitable foils include a 30 μm thick copper foil (type: THE-T9FB) from Suzhou Fukuda Metal Co., Ltd of Suzhou, China, and a 30 μm thick MHT copper foil from OAK-MITSUI LLC, of Hoosick Falls, N.Y., USA. The metal foil may be adhered to the substrate by an adhesive such as an extruded thermoplastic adhesive. Preferred thermoplastic adhesives include ethylene copolymers, acrylic polymers and copolymers, polymethyl methacrylate, polyesters, and blends of such polymers. As shown in
The disclosed integrated back-sheet also comprises a back insulating layer with first and second opposite sides, wherein the first side of the back insulating layer is adhered to the electrically conductive metal circuit. The back insulating layer may be comprised of any suitable inorganic materials, organic materials, or combinations of inorganic and organic materials. Suitable inorganic materials that may comprise the back insulating layers include, without limitation, non-metallic inorganic materials (such as amorphous materials (e.g., glass) or crystalline materials (e.g., quartz)), inorganic compounds, ceramics, and minerals (such as mica or asbestos). Preferably, the back insulating layer is comprised of a polymer that will adhere the electrically conductive metal circuit to the back side of a back-contact solar cell. The back insulating layer is preferably comprised of polymer that remains very viscous at typical photovoltaic module lamination temperatures of 120 to 180° C., and more preferably 125 to 160° C. For example, a thermoplastic polymer with a melt flow rate of in the range of 0 to 100 g/10 min (test condition: 190° C./2.16 kg), and more preferably 0 to 50 g/10 min (test condition: 190° C./2.16 kg) serves well as the back insulating layer because such a polymer remains sufficiently viscous during module thermal lamination so that the back insulating layer holds the photovoltaic cells in a fixed position throughout the module lamination.
The back insulating layer may be formed of a polymer used as an encapsulant material in photovoltaic modules. The back insulating layer may, for example, be a film or sheet comprising, without limitation, polyolefins, poly(vinyl butyral) (PVB), polyurethane (PU), polyvinylchloride (PVC), acid copolymers, silicone elastomers, epoxy resins, or a combination thereof. Suitable polyolefins include, without limitation, polyethylenes, ethylene vinyl acetates (EVA), ethylene acrylate copolymers (such as poly(ethylene-co-methyl acrylate) and poly(ethylene-co-butyl acrylate)), ionomers, polyolefin block elastomers, and the like. Exemplary PVB based materials include, without limitation, DuPont™ PV5200 series encapsulant sheets. Exemplary ionomer based materials include, without limitation, DuPont™ PV5300 series encapsulant sheets and DuPont™ PV5400 series encapsulant sheets from DuPont. Another exemplary polyolefin for the polymeric layer is metallocene-catalyzed linear low density polyethylenes. The back insulating layer may include cross-linking agent that promotes cross-linking upon heating so that the polymer layer remains very viscous throughout the thermal lamination of the module.
The back insulating layer may be comprised of an extruded or cast thermoplastic polymer layer. Thermoplastic ethylene copolymers that can be utilized for the back insulating layer include the ethylene copolymers disclosed in PCT Patent Publication No. WO2011/044417. Preferred ethylene copolymers are comprised of ethylene and one or more monomers selected from the group of consisting of C1-4 alkyl acrylates, C1-4 alkyl methacrylates, methacrylic acid, acrylic acid, glycidyl methacrylate, maleic anhydride and copolymerized units of ethylene and a comonomer selected from the group consisting of C4-C8 unsaturated anhydrides, monoesters of C4-C8 unsaturated acids having at least two carboxylic acid groups, diesters of C4-C8 unsaturated acids having at least two carboxylic acid groups and mixtures of such copolymers, wherein the ethylene content in the ethylene copolymer preferably accounts for 60-90% by weight. The ethylene copolymer used in the back insulating layer may include a copolymer of ethylene and another α-olefin. The ethylene content in the copolymer may account for 60-90% by weight, preferably accounting for 65-88% by weight, and ideally accounting for 70-85% by weight of the ethylene copolymer. The other comonomer(s) preferably constitute 10-40% by weight, more preferably accounting for 12-35% by weight, and ideally accounting for 15-30% by weight of the ethylene copolymer. The ethylene copolymer layer is preferably comprised of at least 70 weight percent of the ethylene copolymer. The ethylene copolymer may be blended with up to 30% by weight, based on the weight of the polymeric layer, of other thermoplastic polymers such as polyolefins, as for example linear low density polyethylene, in order to obtain desired properties. Ethylene copolymers are commercially available. For example, one may be purchased from DuPont under the trade-name Bynel®.
The back insulating layer may further contain any additive or filler known within the art. Such exemplary additives include, but are not limited to, plasticizers, processing aides, flow enhancing additives, lubricants, pigments, dyes, flame retardants, impact modifiers, nucleating agents to increase crystallinity, antiblocking agents such as silica, thermal stabilizers, hindered amine light stabilizers (HALS), UV absorbers, UV stabilizers, anti-hydrolytic agents, light reflection agents, pigments, titanium dioxide, dyes, slip agents, calcium carbonate, dispersants, surfactants, chelating agents, coupling agents, adhesives, primers, reinforcement additives, such as glass fiber, fillers and the like. There are no specific restrictions to the content of the additives and fillers in the back insulating layer as long as the additives do not produce an undue adverse impact on the back insulating layer or its adhesion to the electrically conductive metal circuit or the substrate.
In the embodiment shown in
In the embodiment shown in
In the embodiment shown in
The back insulating layer has a plurality of openings that pass through the back insulating layer and are aligned with the electrically conductive metal circuit. The openings in the back insulating layer are preferably cut and removed by a die-cutting mold or roll.
After the solar cell shaped concave openings 116 are formed in the further polymer layer 114, a plurality of individual openings 118 are formed in the polymer layer 112 using a die cutting mold or roll like the mold 124 shown in
An alternative die-cutting mold 126 is shown in
An electrically conductive adhesive is inserted or injected into the individual openings 118 prior to the introduction of a back-contact solar cell into the concave opening 116. The electrically conductive adhesive is preferably thermally cured for dimensional stability during normal vacuum thermal lamination of the photovoltaic module, and may be an electrically conductive adhesive such as Loctite 3888 or Loctite 5421 from Henkel Corporation, of Germany.
The disclosed assembly for a back-contact photovoltaic module comprises one or more back-contact solar cells aligned over the back insulating layer of the integrated back-sheet. A back-contact solar cell 128, as can be seen in
In the disclosed assembly, a front encapsulant layer 132 is arranged over the front side of the solar cell(s) 128 and a transparent front sheet 134, such as a glass or polymer front sheet is placed over the front encapsulant layer. A typical glass type front sheet is 90 mil thick annealed low iron glass. The front encapsulant layer 132 may be comprised of any of the polymers described above with regard to the back insulating layer. The front encapsulant layer may, for example, be a film or sheet comprising polyolefins, poly(vinyl butyral) (PVB), polyurethane (PU), polyvinylchloride (PVC), acid copolymers, silicone elastomers, epoxy resins, or a combination thereof, including polyethylenes, ethylene vinyl acetates (EVA), ethylene acrylate copolymers, ionomers, polyolefin block elastomers, and the like. The front encapsulant layer 132 may include cross-linking agent that promotes cross-linking upon heating so that the polymer layer remains very viscous throughout the thermal lamination of the module.
After lay-up of the photovoltaic module components is complete, as shown in
Air trapped within the laminate assembly may be removed through a nip roll process. For example, the laminate assembly may be heated in an oven at a temperature of about 80° C. to about 120° C., or preferably, at a temperature of between about 90° C. and about 100° C., for about 30 minutes. Thereafter, the heated laminate assembly may be passed through a set of nip rolls so that the air in the void spaces between the photovoltaic module outside layers, the photovoltaic cell layer and the encapsulant layers may be squeezed out, and the edge of the assembly sealed. This process may provide the final photovoltaic module laminate or may provide what is referred to as a pre-press assembly, depending on the materials of construction and the exact conditions utilized.
The pre-press assembly may then be placed in an air autoclave where the temperature is raised to about 120° C. to about 160° C., or preferably, between about 135° C. and about 160° C., and the pressure is raised to between about 100 psig and about 300 psig, or preferably, about 200 psig (14.3 bar). These conditions are maintained for about 15 minutes to about 1 hour, or preferably, about 20 to about 50 minutes, after which, the air is cooled while no more air is added to the autoclave. After about 20 minutes of cooling, the excess air pressure is vented and the photovoltaic module is removed from the autoclave. The described lamination process should not be considered limiting. Essentially, any photovoltaic module lamination process known within the art may be used to produce the back-contact photovoltaic modules with the integrated back-sheet and the assembly as disclosed herein.
An alternative embodiment is show in
One or more concave openings on the side of the front encapsulant layer 132 that faces the solar cell are dimensioned to correspond to the profile of the back-contact solar cells.
In the disclosed embodiments, cost effective registration of back-contact solar cells is made possible, regardless of whether the cells are placed by machine or by hand. Openings in the back insulating layer are quickly and easily aligned with the electrical contacts on the back side of back-contact solar cells and with the electrically conductive metal circuit integrated with the substrate. The disclosed embodiments provide a back-contact photovoltaic module with integrated back-sheets that can be produced more efficiently and consistently.
The following Examples are intended to be illustrative of the present invention, and are not intended in any way to limit the scope of the present invention.
PET film: Corona treated (both sides) Melinex™ S polyethylene terephthalate film (188 and 250 microns thicknesses) with a density equal to 1.40 g/cm3 obtained from DuPont Teijin Films (U.S.A.);
Ethylene acrylate copolymer resin: Bynel® 22E757 modified ethylene acrylate copolymer resin obtained from DuPont with a density equal to 0.94 g/cm3, an MFI equal to 8.0 g/10 min, and a melting point equal to 92° C.;
Ethylene methacrylic acid copolymer: Nucrel® 0910 copolymer of ethylene and methacrylic acid, made with 9 wt % methacrylic acid, and with a density equal to 0.93 g/cm3, an MFI equal to 10.0 g/10 min, and a melting point equal to 100° C.;
Ethylene-vinyl acetate copolymer resin: Elvax® PV 1650Z extrudable ethylene-vinyl acetate copolymer resin obtained from DuPont obtained from DuPont with a density equal to 0.96 g/cm3, an MFI equal to 31 g/10 min, and a melting point equal to 61° C.
PVF film: Tedlar® polyvinyl fluoride oriented film with a thickness of 38 microns obtained from DuPont.
Adhesive: polyurethane adhesive (PP-5430 and A50) obtained from Mitsui.
Aluminium (Al) foil: 20 micron thick aluminium foil obtained from Shanghai Huxin Aluminum Foil Co., Ltd. of Shanghai, China.
Copper (Cu) foil: 35 micron thick copper foil obtained from Suzhou Fukuda Metal Co., Ltd. of Suzhou, China.
Peel Test Method
Peel strength is a measure of adhesion of laminated samples. Peel strength is measured according to the ASRM D1876 Standard and is expressed in units of N/cm. For example, when the peel strength was tested between a metal foil and a polymer substrate, the metal foil/thermoplastic adhesive/polymer substrate laminate was cut into sample strips of 2.54 cm in width and 10 cm in length, and the thermoplastic adhesive layer and the substrate were fixed respectively in the upper and lower grips of an extension meter to carry out a peeling test at a speed of 5 in/min (12.7 cm/min).
Preparation of Circuit Back-Sheet
The metal foil was laminated to a substrate by an extruded tie layer, and then was cut through die cutting to make patterned circuit. A 188 micron-thick Melinex™ S PET film was corona treated on both sides. A 38 micron-thick Tedlar® oriented PVF film obtained from DuPont was adhered to one side of the PET film using a 10 micron thick layer of Mitsui PP-5430 polyurethane adhesive. On an extrusion-lamination machine manufactured by Davis Standard, a 1:1 (w/w) blend of Bynel® 22E757 ethylene methyl acrylate copolymer from DuPont and Nucrel® 0910 copolymer ethylene and methacrylic acid resin from DuPont was extruded at an extrusion temperature of 285° C. between the metal foil and the side of the PET film opposite of the PVF film to form a tie layer adhesive film with a thickness of about 100 microns.
The substrate structure, metal foil, tie layer formulation, and process temperature are summarized in Table 1.
A flat die cutting press by Suzhou Tianhao electronic material Co., Ltd of Suzhou, China was used to cut through both the metal foil and tie layer adhesive film without cutting the underlying PET film. The copper foil and interlayer adhesive were die cut in a zig zag pattern like that shown in
The TPCu die cut circuit back-sheet described above was used to prepare an assembly for a back-contact photovoltaic module. On an extrusion-lamination machine manufactured by Davis Standard, a first 300 micron-thick EVA layer (Elvax® 1650Z resin with peroxide cross-linking agent) was extrusion coated at an extrusion temperature of 100° C. onto the copper foil like the layer 112 shown in
Die cutting was used to make a concave opening in the second EVA layer and to make electrical contact openings through the first EVA layer for registration of back contact solar cell electrical contacts. First, a flat die mold like the mold shown in
The TPCu die cut circuit back-sheet described above was used to prepare an assembly for a back-contact photovoltaic module as describe in Example 1. First and second EVA layers were extruded over the TPCu die cut circuit back-sheet with the same formulation and by the same process as described in Example 1.
A concave opening was formed in the second EVA layer corresponding to the shape of a back-contact solar cell, and multiple opening corresponding to the back-contact solar cell contacts were formed in the first EVA layer as shown in
The TPCu die cut circuit back-sheet described above was used to prepare an assembly for a back-contact photovoltaic module. On an extrusion-lamination machine manufactured by Davis Standard, a first 300 micron-thick ethylene copolymer tie layer was extrusion coated at an extrusion temperature of 260° C. onto the copper foil like the layer 112 shown in
Die cutting was used to make a concave opening in the EVA layer and to make electrical contact openings through the tie layer for registration of back contact solar cell electrical contacts. A single die mold like the mold shown in
The TPCu die cut circuit back-sheet described above was used to prepare an assembly for a back-contact photovoltaic module. On an extrusion-lamination machine manufactured by Davis Standard, a first 300 micron-thick ethylene copolymer tie layer was extrusion coated at an extrusion temperature of 260° C. onto the copper foil like the layer 112 shown in
Die cutting was used to make a concave opening in the EVA layer and to make electrical contact openings through the tie layer for registration of back contact solar cell electrical contacts. A single die mold like the mold shown in
The TPAI die cut circuit back-sheet with aluminum foil circuit as described above was used to prepare an assembly for a back-contact photovoltaic module. On an extrusion-lamination machine manufactured by Davis Standard, a first 300 micron-thick ethylene copolymer tie layer was extrusion coated at an extrusion temperature of 270° C. onto the copper foil like the layer 112 shown in
Die cutting was used to make a concave opening in the EVA layer and to make electrical contact openings through the tie layer for registration of back contact solar cell electrical contacts. A single die mold like the mold shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 201210514833.3 | Dec 2012 | CN | national |
