Patent Application
20160134231
This invention relates to photovoltaic (PV) modules and racks for mounting the same. In one aspect the invention relates to PV modules made from plastic while in another aspect, the invention relates to PV modules that are easily assembled into an array of PV modules without the need for bolts, screws or other metal fasteners. In one aspect the invention relates to a plastic composition for making PV module frames and racks.
Photovoltaic modules, also known as solar modules, are constructions for the direct generation of electricity from sunlight. They comprise, among other components, one or more, typically a plurality, of PV or solar cells within a frame. The frame provides mechanical support for the PV cells against mechanical forces such as wind. The frame and the racks upon which a plurality of PV modules are assembled into a PV modular array require good mechanical strength and thermal dimensional stability.
Currently, aluminum is the material of choice for PV module frames and racks because of its relative low cost and high mechanical strength. However, aluminum has a number of drawbacks. Because of its conductive nature, PV modules with an aluminum frame can experience current leakage, and current leakage can degrade the conductive layer of PV cell. Moreover, aluminum PV frames (and racks) need to be grounded for safety reasons, and this can become a serious cost issue for applications with many modules, e.g., for solar farms. In addition, aluminum is heavy relative to other materials, e.g., plastics, and typically, the lighter the frame, the better.
Recently, a number of companies that manufacture PV module frames began exploring the replacement of aluminum with any one of, or combination of, various polymers such as polyamide (PA), polyphenylene ether/polystyrene (PPE/PS), polyamide/polybutylene terephthalate (PA/PBT), and polyamide/polyphenylene ether/polystyrene (PA/PPE/PS), glass fiber reinforced acrylonitrile/styrene/acrylate (ASA) (available from BASF), and polyurethane systems (available from Bayer). However, not only does the search continue for plastics useful in this application, but also for better frame and rack designs.
Aluminum frames and racks often comprise many pieces that require assembly with screws, bolts and other metal fasteners and this, in turn, can make for a slow and inefficient assembly. Junction boxes are not integrated into the frame, and thus require separate attachment. Many long power cords are frequently necessary to connect modules with one another into an array. Concrete piers or ballast is often required to secure the modules or an array of modules to a base. These and other considerations drive a desire for not only a nonmetal material for PV module frames and racks, but also for better PV module frame and rack designs.
In one embodiment the invention is a composition comprising (A) a thermoplastic polymer, particularly a thermoplastic polyolefin (TPO), (B) a reinforcing element, particularly glass fiber, (C) a non-halogen containing, intumescent flame retardant, (D) an impact-modifier, (E) a coupling agent, and, optionally, (F) one or more additives such as an antioxidant, UV-stabilizer, etc.
In one embodiment the invention is a frame, rack, or frame or rack component made from a composition comprising (A) a thermoplastic polymer, particularly a thermoplastic polyolefin (TPO), (B) a reinforcing element, particularly glass fiber, (C) a non-halogen containing, intumescent flame retardant, (D) an impact-modifier, particularly a polyolefin elastomer that is not the thermoplastic polymer of (A), (E) a coupling agent, and, optionally, (F) one or more additives such as an antioxidant, UV-stabilizer, etc.
In one embodiment the invention is a solar panel assembly comprising a:
In one embodiment the invention is a plastic PV module frame characterized by (A) a unitary molded or over-molded part, (B) an L-shape, (C) a two-piece junction box with one piece located on one side of the frame and the other piece located opposite and on the other side of the frame; (D) a self-alignment device, and (E) at least one structural member on the back of the panel to provide mechanical strength to the panel.
In one embodiment the invention is a photovoltaic assembly comprising:
Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percentages are by weight. For purposes of United States patent practice, the contents of any referenced patent, patent application or publication are incorporated by reference in their entirety (or its equivalent U.S. version is so incorporated by reference) especially with respect to the disclosure of synthetic techniques, definitions (to the extent not inconsistent with any definitions specifically provided in this disclosure), and general knowledge in the art.
The numerical ranges in this disclosure are approximate, and thus may include values outside of the range unless otherwise indicated. Numerical ranges include all values from and including the lower and the upper values, in increments of one unit, provided that there is a separation of at least two units between any lower value and any higher value. As an example, if a compositional, physical or other property, such as, for example, molecular weight, viscosity, melt index, etc., is from 100 to 1,000, it is intended that all individual values, such as 100, 101, 102, etc., and sub ranges, such as 100 to 144, 155 to 170, 197 to 200, etc., are expressly enumerated. For ranges containing values which are less than one or containing fractional numbers greater than one (e.g., 1.1, 1.5, etc.), one unit is considered to be 0.0001, 0.001, 0.01 or 0.1, as appropriate. For ranges containing single digit numbers less than ten (e.g., 1 to 5), one unit is typically considered to be 0.1. These are only examples of what is specifically intended, and all possible combinations of numerical values between the lowest value and the highest value enumerated, are to be considered to be expressly stated in this disclosure. Numerical ranges are provided within this disclosure for, among other things, the relative amounts of the various components in the composition from which the PV module frame and racks are manufactured.
“Comprising,” “including,” “having,” and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term “comprising” may include any additional additive, adjuvant or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, “consisting essentially of” excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability. The term “consisting of” excludes any component, step or procedure not specifically delineated or listed.
In one embodiment the invention is a composition comprising (A) a thermoplastic polymer, (B) a reinforcing element, (C) a non-halogen containing, intumescent flame retardant, (D) an impact-modifier, (E) a coupling agent, and, optionally, (F) one or more additives. In one embodiment the invention is a composition comprising, based on the weight of the composition, (A) 10-80 wt % of a thermoplastic polymer, (B) 10-55 wt % of a reinforcing element, (C) 1-30 wt % of a non-halogen containing, intumescent flame retardant, (D) 1-20 wt % of an impact-modifier, (E) 0.001-0.5 wt % of a coupling agent, and, optionally, (F) one or more additives.
In one embodiment the invention is a photovoltaic (PV) frame, PV rack, or PV frame or PV rack component made from a composition comprising (A) a thermoplastic polymer, particularly a thermoplastic polyolefin (TPO), (B) a reinforcing element, particularly glass fiber, (C) a non-halogen containing, intumescent flame retardant, (D) an impact-modifier, particularly a polyolefin elastomer that is not the thermoplastic polymer of (A), (E) a coupling agent, and, optionally, (F) one or more additives such as an antioxidant, UV-stabilizer, etc. In one embodiment the invention is a photovoltaic (PV) frame, PV rack, or PV frame or PV rack component made from a composition comprising based on the weight of the composition, (A) 10-80 wt % of a thermoplastic polymer, (B) 10-55 wt % of a reinforcing element, (C) 1-30 wt % of a non-halogen containing, intumescent flame retardant, (D) 1-20 wt % of an impact-modifier, (E) 0.001-0.5 wt % of a coupling agent, and, optionally, (F) one or more additives.
Nonlimiting examples of suitable thermoplastic polymers include, but are not limited to, olefin-based polymers, polyamides, polycarbonates, polyesters, thermoplastic polyurethanes, thermoplastic polyesters, polystyrenes, high impact polystyrenes, polyphenylene oxides, and any combination thereof. In one embodiment, the thermoplastic polymer is a halogen-free polymer. As here used “halogen-free” means the absence of a halogen other than that which may be present as a contaminant.
In one embodiment the thermoplastic polymer is an olefin-based polymer. As used herein, an “olefin-based polymer” is a polymer containing, in polymerized form, an olefin, for example ethylene or propylene. The olefin-based polymer may contain a majority weight percent of the polymerized form of the olefin based on the total weight of the polymer. Nonlimiting examples of olefin-based polymers include ethylene-based polymers and propylene-based polymers. In one embodiment the olefin-based polymer is an ethylene-based polymer. Nonlimiting examples of suitable ethylene-based polymers include ethylene/α-olefin copolymers (ethylene/propylene copolymer, ethylene/butene copolymer, ethylene/octene copolymer), ethylene/(acrylic acid)copolymer, ethylene/methylacrylate copolymer, ethylene/ethylacrylate copolymer, ethylene/vinyl acetate copolymer, ethylene/propylene/diene copolymer, and any combination thereof. In one embodiment the olefin-based polymer is a propylene-based polymer. Nonlimiting examples of suitable propylene-based polymers include propylene homopolymers and propylene copolymers including impact-modified polypropylene (IPP). The thermoplastic polymer provides flexibility, solvent resistance, thermal stability and/or mechanical strength to the final composition.
In one embodiment the thermoplastic polymer is an ethylene/α-olefin copolymer, an olefin block ethylene/α-olefin copolymer, or a combination thereof. In one embodiment the thermoplastic polymer is an ethylene/butene copolymer. In one embodiment the thermoplastic polymer is an olefin block ethylene/butene copolymer.
In one embodiment the thermoplastic polymer is an IPP. Impact-modified polypropylene is a known polymer and comprises at least two major components,
Component A and Component B. Component A is preferably an isotactic propylene homopolymer, though small amounts of a comonomer may be used to obtain particular properties. Typically such copolymers of Component A contain 10% by weight or less, preferably less than 6% by weight or less, comonomer such as ethylene, butene, hexene or octene. Most preferably less than 4% by weight ethylene is used. The end result is usually a product with lower stiffness but with some gain in impact strength compared to homopolymer Component A.
As here used Component A refers generally to the xylene insoluble portion of the IPP composition, and Component B refers generally to the xylene soluble portion. Where the xylene soluble portion clearly has both a high molecular weight component and a low molecular weight component, the low molecular weight component is attributable to amorphous, low molecular weight propylene homopolymer. Therefore, Component B in such circumstances refers only the high molecular weight portion.
Component B is most preferably a copolymer consisting essentially of propylene and ethylene although other propylene copolymers, ethylene copolymers or terpolymers may be suitable depending on the particular product properties desired. For example, propylene/butene, hexene or octene copolymers, and ethylene/butene, hexene or octene copolymers may be used, and propylene/ethylene/hexene-1 terpolymers may be used. In a preferred embodiment though, Component B is a copolymer comprising at least 40% by weight propylene, more preferably from 80% by weight to 30% by weight propylene, even more preferably from 70% by weight to 35% by weight propylene. The comonomer content of Component B is preferably in the range of from 20% to 70% by weight comonomer, more preferably from 30% to 65% by weight comonomer, even more preferably from 35% to 60% by weight comonomer. Most preferably Component B consists essentially of propylene and from 20% to 70% ethylene, more preferably from 30% to 65% ethylene, and most preferably from 35% to 60% ethylene.
In one embodiment the thermoplastic polymer typically comprises from 10 to 80, more typically from 25 to 70, weight percent (wt %) of the composition.
Nonlimiting examples of suitable reinforcing elements include, but are not limited to, glass fibers, carbon fibers, talc, calcium carbonate, organoclay, marble dust, cement dust, feldspar, silica or glass, fumed silica, silicates, alumina, ammonium bromide, antimony trioxide, antimony trioxide, zinc oxide, zinc borate, barium sulfate, silicones, aluminum silicate, calcium silicate, titanium oxides, glass microspheres, chalk, mica, clays, wollastonite, ammonium octamolybdate, intumescent compounds, expandable graphite, and mixtures thereof. The reinforcing elements may contain various surface coatings or treatments, such as silane, fatty acids, and the like. Glass fiber, particularly long glass fiber, is the preferred reinforcing element.
In one embodiment the reinforcing element typically comprises from 10 to 55, more typically from 25 to 40, weight percent (wt %) of the composition.
In one embodiment the non-halogen containing, intumescent flame retardant (FR) system used in the practice of this invention comprises one or more organic phosphorus-based and/or nitrogen-based intumescent FR, optionally including a piperazine component. In one embodiment the non-halogen containing, intumescent FR system typically comprises from 1 to 30, more typically from 5 to 25, weight percent (wt %) of the composition.
In one embodiment the non-halogen containing, intumescent FR system comprises at least 1, 10, 15, 20 and most preferably at least 30 wt % of an organic nitrogen/phosphorus-based compound. The typical maximum amount of the organic nitrogen/phosphorus-based compound does not exceed 70, 60, 50, and more preferably does not exceed 45, wt % of the non-halogen containing, intumescent FR system.
In an embodiment the non-halogen containing, intumescent FR system comprises 30-99 wt % of a piperazine based compound. The preferred amount of the piperazine based compound is at least 30, 40, and at least 50, wt %. In particular embodiments the FR system can comprise 55-65 wt % of a piperazine based compound and 35-45 wt % of one or more other flame retardants (e.g., an organic nitrogen/phosphorus-based compound).
Nonlimiting examples of suitable non-halogen containing, intumescent flame retardants include, but are not limited to, organic phosphonic acids, phosphonates, phosphinates, phosphonites, phosphinites, phosphine oxides, phosphines, phosphites or phosphates, phosphonitrilic chloride, phosphorus ester amides, phosphoric acid amides, phosphonic acid amides, phosphinic acid amides, and melamine and melamine derivatives, including melamine polyphosphate, melamine pyrophosphate and melamine cyanurate, and mixtures of two or more of these materials. Examples include phenylbisdodecyl phosphate, phenylbisneopentyl phosphate, phenyl ethylene hydrogen phosphate, phenyl-bis-3,5,5′-trimethylhexyl phosphate), ethyldiphenyl phosphate, 2-ethylhexyl di(p-tolyl) phosphate, diphenyl hydrogen phosphate, bis(2-ethyl-hexyl) p-tolylphosphate, tritolyl phosphate, bis(2-ethylhexyl)-phenyl phosphate, tri(nonylphenyl) phosphate, phenylmethyl hydrogen phosphate, di(dodecyl) p-tolyl phosphate, tricresyl phosphate, triphenyl phosphate, triphenyl phosphate, dibutylphenyl phosphate, 2-chloroethyldiphenyl phosphate, p-tolyl bis(2,5,5′-trimethylhexyl) phosphate, 2-ethylhexyldiphenyl phosphate, and diphenyl hydrogen phosphate. Phosphoric acid esters of the type described in U.S. Pat. No. 6,404,971 are examples of phosphorus-based FRs. Additional examples include liquid phosphates such as bisphenol A diphosphate (BAPP) (Adeka Palmarole) and/or resorcinol bis(diphenyl phosphate) (Fyroflex RDP) (Supresta, ICI), and solid phosphorus such as ammonium polyphosphate (APP), piperazine pyrophosphate, piperazine orthophosphate and piperazine polyphosphate. APP is often used with flame retardant co-additives, such as melamine derivatives. Also useful is Melafine (DSM) (2,4,6-triamino-1,3,5-triazine; fine grind melamine)
Examples of the optional piperazine components of the FR system include compounds such as piperazine pyrophosphate, piperazine orthophosphate and piperazine polyphosphate. Additional examples include polytriazinyl compounds or oligomer or polymer 1,3,5-triazine derivatives including a piperazine group, as described in US 2009/0281215 and WO 2009/016129.
Impact modifiers are materials added to a substance to improve the resistance of the substance to deformation and/or breaking. In the context of improving the resistance of plastic to deformation and/or breading, non-limiting examples of impact modifiers includes natural and synthetic rubbers (e.g., ethylene propylene rubbers (EPR or EPDM)), ethylene vinyl acetate (EVA), styrene-block copolymers (SBC), poly vinyl chloride (PVC) and polyolefin elastomers (POE).
While any elastomeric polyolefin can be used in the practice of this invention, preferred elastomeric polyolefins are made with a single site catalyst, such as a metallocene catalyst or constrained geometry catalyst, typically have a melting point of less than 95, preferably less than 90, more preferably less than 85, even more preferably less than 80 and still more preferably less than 75, ° C.
The elastomeric polyolefin copolymers useful in the practice of this invention include ethylene/α-olefin interpolymers having an a-olefin content of between 15, preferably at least 20 and even more preferably at least 25, wt % based on the weight of the interpolymer. These interpolymers typically have an a-olefin content of less than 50, preferably less than 45, more preferably less than 40 and even more preferably less than 35, wt % based on the weight of the interpolymer. The a-olefin content is measured by 13C nuclear magnetic resonance (NMR) spectroscopy using the procedure described in Randall (Rev. Macromol. Chem. Phys., C29 (2&3)). Generally, the greater the α-olefin content of the interpolymer, the lower the density and the more amorphous the interpolymer, and this translates into desirable physical and chemical properties as an impact modifier.
The α-olefin is preferably a C3-20 linear, branched or cyclic α-olefin. The term interpolymer refers to a polymer made from at least two monomers. It includes, for example, copolymers, terpolymers and tetrapolymers. Examples of C3-20 α-olefins include propene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, and 1-octadecene. The α-olefins also can contain a cyclic structure such as cyclohexane or cyclopentane, resulting in an α-olefin such as 3-cyclohexyl-1-propene (allyl cyclohexane) and vinyl cyclohexane. Although not α-olefins in the classical sense of the term, for purposes of this invention certain cyclic olefins, such as norbornene and related olefins, particularly 5-ethylidene-2-norbornene, are α-olefins and can be used in place of some or all of the α-olefins described above. Similarly, styrene and its related olefins (for example, α-methylstyrene, etc.) are α-olefins for purposes of this invention. Illustrative polyolefin copolymers include ethylene/propylene, ethylene/butene, ethylene/1-hexene, ethylene/1-octene, ethylene/styrene, and the like. Illustrative terpolymers include ethylene/propylene/1-octene, ethylene/propylene/butene, ethylene/butene/1-octene, ethylene/propylene/diene monomer (EPDM) and ethylene/butene/styrene. The copolymers can be random or blocky.
The elastomeric polyolefin copolymers useful in the practice of this invention have a glass transition temperature (Tg) of less than −20, preferably less than −40, more preferably less than −50 and even more preferably less than −60, C as measured by differential scanning calorimetry (DSC) using the procedure of ASTM D-3418-03. Moreover, typically the elastomeric polyolefin copolymers used in the practice of this invention also have a melt index (as measured by ASTM D-1238 (190° C./2.16 kg)) of less than 100, preferably less than 75, more preferably less than 50 and even more preferably less than 35, g/10 minutes. The typical minimum MI is 1, and more typically it is 5.
More specific examples of elastomeric olefinic interpolymers useful in this invention include very low density polyethylene (VLDPE) (e.g., FLEXOMER ethylene/1-hexene polyethylene made by The Dow Chemical Company), homogeneously branched, linear ethylene/α-olefin copolymers (e.g. TAFMER by Mitsui Petrochemicals Company Limited and EXACT by Exxon Chemical Company), and homogeneously branched, substantially linear ethylene/α-olefin polymers (e.g., AFFINITY and ENGAGE polyethylene available from The Dow Chemical Company). The more preferred elastomeric polyolefin copolymers are the homogeneously branched linear and substantially linear ethylene copolymers. The substantially linear ethylene copolymers are especially preferred, and are more fully described in U.S. Pat. Nos. 5,272,236, 5,278,272 and 5,986,028.
While the thermoplastic polymer (the A component of the composition) and the impact modifier (the D component of the composition) can both be a polyolefin elastomer, they are never the same polyolefin elastomer in any given composition. In other words, if the thermoplastic polymer is an ethylene-propylene copolymer, then the impact modifier is something other than an ethylene-propylene copolymer, e.g., an ethylene-butene copolymer, or an ethylene-octene copolymer, or an EPDM, etc. In one embodiment, the composition comprises an IPP as the thermoplastic polymer (component A) and a substantially linear ethylene copolymer, e.g., an ENGAGE elastomer, as the impact modifier (component D).
In one embodiment the impact modifier typically comprises from 1 to 20, more typically from 5 to 15, wt % of the composition.
In one embodiment the coupling agents used in the composition of this invention include, but are not limited to, bis(sulfonyl azide) (BSA), ethylene vinyl acetate (EVA) copolymer (e.g., ELVAX 40L-03 (40%VA, 3MI) by DuPont), and aminated olefin block copolymers (e.g., INFUSE 9807 by The Dow Chemical Company). Examples of other coupling agents include polysiloxane containing vinyl and ethoxy groups (e.g., DYNASYLAN 6498 (oligomeric vinyl silane)) and hydroxy-terminated dimethylsiloxane (<0.1 vinyl acetate). In one embodiment the coupling agent typically comprises from 0.001 to 0.5 wt % of the composition.
The compositions of this invention can incorporate one or more stabilizers and/or additives such as, but not limited to, antioxidants (e.g., hindered phenols such as IRGANOXTM 1010 (Ciba/BASF)), thermal (melt processing) stabilizers, hydrolytic stability enhancers, heat stabilizers, acid scavengers, colorants or pigments, UV stabilizers, UV absorbers, nucleating agents, processing aids (such as oils, organic acids such as stearic acid, metal salts of organic acids), antistatic agents, smoke suppressants, anti-dripping agents, tougheners, plasticizers (such as dioctylphthalate or epoxidized soy bean oil), lubricants, emulsifiers, optical brighteners, silanes (in free form or as filler surface modifier), cement, urea, polyalcohols like pentaerythritol, minerals, peroxides, light stabilizers (such as hindered amines), mold release agents, waxes (such as polyethylene waxes), viscosity modifiers, charring agents (e.g., pentaerythritol), and other additives, to the extent that these additives do not interfere with the desired physical or mechanical properties of the articles made from the compositions of the present invention. If present, then these additives are used in known amounts and in known ways, but typically the additive, or package of additives, comprises greater than zero, e.g., 0.01, to 2, more typically 0.1 to 1, wt % of the final composition. Examples of useful viscosity modifiers include polyether polyols such as VORANOL 3010 and VORANOL 222-029, available from The Dow Chemical Company). Useful commercially available anti-dripping agents include triglycidyl isocyanurate(TGIC), VIKOFLEX 7010 (methyl epoxy soyate (epoxidized ester family)), and VIKOLOX alpha olefin epoxy (C-16) (mixture of 1,2-epoxyhexadecane (>95 wt %) and 1-hexadecene (<5 wt %), both available from eFAME. A useful dispersant/metal chelater is n-octylphosphonic Acid (UNIPLEX OPA).
Compounding of the compositions of this invention can be performed by standard means known to those skilled in the art. Examples of compounding equipment are internal batch mixers, e.g., BANBURY or BOLLING internal mixer. Alternatively, continuous single or twin screw mixers can be used, e.g., FARREL continuous mixer, WERNER and PFLEIDERER twin screw mixer, or BUSS kneading continuous extruder. The type of mixer utilized, and the operating conditions of the mixer, will affect properties of the composition such as viscosity, volume resistivity, and extruded surface smoothness. The compounding temperature of the polymer blend with the FR and optional additive packages is typically from 120° to 220° C., more typically from 160° to 200° C. The various components of the final composition can be added to and compounded with one another in any order, or simultaneously, but typically a compatibilizers (if included) is first compounded with the IPP and the thermoplastic polymer is first compounded with one or more of the components of the FR package, and the two mixtures with any remaining components of the FR package and any additives are compounded with one another. In some embodiments, the additives are added as a pre-mixed masterbatch, which are commonly formed by dispersing the additives, either separately or together, into an inert plastic resin, e.g., one of the IPP or thermoplastic polymer. Masterbatches are conveniently formed by melt compounding methods.
The following drawings illustrate various embodiments of the prior art and the invention. Like components and parts are like numbered throughout the drawings.
As shown in
Rear base attachments 35C and 35D also comprise slots to receive and hold the height edges of wind deflector 36. This is illustrated in
In one embodiment of the invention, the PV module frame is characterized by one or more of the following features: (A) a single molded or over-molded part, (B) an L-shape, (C) a two-piece junction box with one piece located on one side of the frame and the other piece located opposite and on the other side of the frame; (D) no observable wire on the backside of the panel (from the perspective of looking at the front side of the panel), (E) a self-alignment device, and (F) at least one structural member on the back of the panel to provide mechanical strength to the panel. In one embodiment the PV module of this invention is characterized by two, or three, or four, or five, or all six of these features which are more fully described in
In
PV module 54 is also equipped with structural beams 58A and 58B. In one embodiment the PV module is equipped with one beam. In another embodiment the PV module is equipped with more than two beams. In one embodiment the PV module is without a beam. The structural beams, when present, provide mechanical strength to the photovoltaic array.
As shown in
Assembly of the frame is quick and simple. The L-shaped frame is laid on a flat surface with the open side up, i.e., one leg of the L flat on the surface and the other leg of the L extending perpendicularly upward. A sealer is applied to the inside of the frame and/or the edges of the photovoltaic array panel, and then the panel is inserted into the open frame such the sealer is between the panel edges and the frame. The sealer is then allowed to cure so that the panel is securely affixed to the frame.
The structural beams are then inserted and affixed to the frame by any convenient method, e.g., mechanical fastener, compression fit, adhesive, etc., and the assembled module is then slid onto the rails. The modules are snap-fitted together using the aligning devices, the junction boxes coupled with either a soft wire, e.g., 49 in
The L-shaped frame allows for the construction of a PV module with a smaller footprint (e.g., 2.5% or more) because less space is needed between the edge of the photovoltaic array and the frame. This reduces the modules weight and cost of construction.
In one embodiment of the invention, the PV module frame comprises a (i) back sheet, preferably with an integrated junction box, and (ii) four straight side frame segments joined together into a rectangular configuration by four corner connectors. The back sheet can be laminated with solar cell layers. The PV modules can be fixed into an array through the use of cross anchor blocks.
The PV module, frame and/or anchor blocks are characterized by one or more of the following features:
One embodiment of the corner connectors is more fully described in
In the installation of a solar panel array on a rooftop or other surface, first the anchor blocks are laid out in the desired pattern (e.g.,
In one embodiment of the invention, PV module comprises an angle corner connector. This connector imparts good strength and stiffness and a clean look to the PV module while affording easy assembly of the module.
This embodiment is illustrated in
All of the corner connectors of any given PV module are essentially alike is size, shape and function. As shown in
The tabs on the connectors are sized and shaped to be received and held by a section of frame. Each frame section has two slots or other apertures (one on each end) that correspond in size and shape with a tab of the connector (e.g.,
Once the PV module corner is formed by the joining of two frame sections, e.g., 83B and 83C, with a corner connector (inside frames 83B and 83C and thus not shown), and typically after the PV module solar array panel and structural backsheet, if any, have been inserted into the frame, the outer sides of the corner seams are welded together using laser 89 or similar tool (
In one embodiment of the invention, the PV module comprises a frame structure with hinge and snap-fit features. The module is characterized by (i) a one-molded part frame with an integrated hinged frame cover, (ii) an edge step on the frame edges to support a solar cell array panel, (iii) snap-fit covers, and (iv) an integrated junction box on a frame edge. The hinged frame cover snap fits with the frame bottom, it can be unitary or multi-segmented, and if unitary, i.e., a single molded part, then it can either be molded with the frame or separate from the frame. The design of this embodiment can result in bending strength better than that of multi-part structures, reduced assembly complexity and time, reduced manufacturing costs relative to the separate manufacture of cover and frame, and assist in securing the solar panel array to the frame.
Assembly of PV module 91A is easy and quick. Bottom frames 93A-D can be molded as a single integrated piece or as separate pieces assembled into the desired configuration in any convenient manner such as those described elsewhere in this specification. Frame covers 92A-D can also be molded as part of a single integrated construction with frame bottoms 93A-D (a preferred construction with the frame covers hinged to the frame bottoms), or the frame covers can be molded in separate pieces which are separately attached during the construction process (in this embodiment, hinges are not part of the construction). Assembly is simply placing a solar cell array panel sized to the frame onto the frame bottom such that each edge of the panel rests on a corresponding frame edge, and then closing the frame covers over these edges of the panel such that the plunger enters and engages its corresponding well. In one embodiment of this invention, one or more of frame bottoms 93A-D comprises an integrated junction box as further described in this specification.
In one embodiment of the invention, the PV module is manufactured by a blow molding process. This process allows for the manufacturing of hollow parts with complex shapes, allows for the integration of structural backsheets and junction boxes, and provides a high stiffness to weight ratio (which will reduce the weight, and thus cost, of the module).
The process of this embodiment comprises the steps of filling a thermoplastic olefin (TPO) with long glass fiber to produce a high rigidity, low shrink composite. The TPO composite is compounded with additives including, but not limited to, UV-stabilizers, pigments or dyes, antioxidants and nucleating agents. The TPO composite may also contain filler which emits energy via radiation to ensure that the PV module emits heat during operation and thus maximizing cell efficiency. These cooling particles can comprise silicon carbide, silicon dioxide and the like.
The TPO composite is extruded using conventional blow molding equipment and conditions to produce an integrated frame and backsheet such as that described in
In one embodiment of the invention, the PV module is produced using an over-molding process. The process is one-step and produces a frame with better sealing performance. The PV module, frame and/or process are characterized by one or more of the following features:
In one embodiment of the invention, the mounting rack of the PV module is integrated into the module itself. This design results in installation savings of cost and time.
In one embodiment of the invention, the PV module is characterized by a one-piece, integrated frame with a closeable entry on one edge through with a solar panel assembly can be inserted. The frame provides four-edge support for the assembly, and the entry port through which the assembly is inserted into the frame can be closed and sealed, typically with a snap-fit lid.
The PV module is characterized by one or more of the following features:
The sufficient sealant is applied to securely close the lid over the inserted assembly. In one embodiment the sealant also serves as an adhesive between the upper and lower portions of the frame. The composition of the sealant is not critical to the practice of this invention.
The composition of the frame can also vary to convenience, and can be either a thermoplastic or thermoset material. Typically the material from which the frame is formulated has a Young's modulus of 1.5 MPa to 30 MPa, and the modulus can be enhanced by including fiber (e.g., glass fiber, carbon fiber, etc.) into the formulation. The composition can be enhanced with various additives such as antioxidants, UV stabilizers, pigments, dyes, nucleating agents, flame retardant agents and the like. The composition can also can one or more fillers to ensure that the module emits heat during operation and maximizes cell efficiency. These fillers include silicon carbide, silicon dioxide, boron nitride and the like.
With the one-molded part design, the PV module frame of this embodiment provides good resistance to bending/flexing and reduces assembly of the module with the integrated junction box and easy insertion of the solar panel assembly.
In one embodiment of the invention, the PV module is characterized by a back panel comprising a bottom skin and a plurality of spaced apart supporting legs. The legs are attached to the bottom surface of photovoltaic laminate in a manner that creates open channels or chimneys that assist in the cooling of the PV module.
The PV module is characterized by one or more of the following features:
In one embodiment of the invention, multiple PV module layers are laminated to an integrated frame and structural backsheet in a single step. The multiple PV module layers comprise a top transparent polymer or glass layer, an encapsulated layer, and a silicon layer. The encapsulated layer typically comprises a polymer such as ethylene vinyl acetate (EVA). The lamination is conducted in a laminating device and under pressure or vacuum conditions. After lamination an adhesive, e.g., silicon rubber, is applied to seal the edges of the solar cell layers.
Multiple PV module encapsulant processing includes the steps of placing a sheet of material onto glass, and then placing onto it pre-sorted and connected solar cells. Another layer of sheet encapsulant is then placed on top of this, followed by a final structural backsheet integrated with a module frame on the back of the solar panel. The completed laminate is then placed into a laminator machine, which is heated to an optimum temperature to melt the encapsulant material. In one embodiment an over-pressure is applied to the laminate to facilitate the lamination process. In one embodiment a vacuum is then applied to remove any air bubbles trapped during the heating process, resulting in a sealed solar cell array that is bonded to a glass surface. This process laminates the structural backsheet with frame onto the cell layers together to shorten the cycle time of module assembly process.
The resulting laminated product exhibits improved bending strength relative to PV products made conventionally. This one-step process of joining the PV lamination to the frame reduces the assembly process of the finished product, i.e., the PV module. With the inclusion of ribs on the backsheet, the PV module exhibits desirable bending and twisting stiffness and strength. In one preferred embodiment a junction box is integrated into the back sheet structure.
Table 1 reports the materials used in these examples.
FR additive, antioxidant, UV-stabilizer, color masterbatch, ENGAGE 8200 and SK B391G are premixed in a high speed mixer at 900 revolutions per minute (rpm) for 3 minutes. The mixture is fed into the main feed port of an ZSK40 extruder (L/D=48). The screw speed is set at 250 rpm, and the barrel temperature is 190-200° C. The feed rate is 30 kilograms per hour (kg/h). The nitrogen inlet is used on the second zone to protect the material during compounding. Vacuum is open to remove the volatiles. The strands are cooled by water then cut into pellets.
The PP resin and DPO-bisulphonyl azide coupling agent at 400˜800 ppm) and glass fiber with weight ratio 50:50 are fed into the main port of the ZSK40 (L/D=48) extruder according to the formulation. Glass fiber is fed into the vent port at zone 5. The screw speed is set at 250 rpm, and the barrel temperature at 190-200° C. The feed rate is 40 kg/h. Vacuum is open to remove the volatiles. The strands are water cooled and then cut into pellets.
GF reinforced IPP masterbatch pellets and FR masterbatch with at a weight ratio 50:50 are fed an into injection molding apparatus. The barrel temperature is set at 70° C., 190° C., 200° C., 200° C., and 200° C. The mold temperature is 30° C. ASTM standard test specimens for mechanical, electrical and FR tests are injection molded on a FANUC machine.
Tensile strength and flexural strength testing are conducted by an INSTRON 5565 according to ASTM D638.
Izod Impacted Strength testing is conducted on a CEIST 6960 according to ASTM D256.
The UL94 vertical flammability testing is conducted by a UL94 chamber according to ASTM D 3801.
The 1000 hour UV exposure is conducted by a QUV from Q-lab according to IEC61215.
Table 2 reports the performance for different glass fiber reinforced IPP composites. The addition of intumescent FR system 50A-2 improves the FR performance dramatically. With 20% 50A-2 (Invention Example 1), the composite can achieve UL94 V-0 (3.2 mm), and shows a good balance for mechanical performance and weather resistance compared to Comparative Example 1. With 25% 50A-2 (Invention Example 1), the composite can achieve UL94 V-0 (1.6 mm) In contrast, with 40% Mg(OH)2 (Comparative Example 2) the composite fails the UL94 V-0 (3.2 mm) testing.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2013/078421 | 6/28/2013 | WO | 00 |
