The present invention relates to photovoltaic modules and methods of production.
Photovoltaic modules can include semiconductor material deposited over a substrate, for example, with a first layer serving as a window layer and a second layer serving as an absorber layer. The semiconductor window layer can allow the penetration of solar radiation to the absorber layer, such as a cadmium telluride layer, which converts solar energy to electricity. Photovoltaic modules can also contain one or more transparent conductive oxide layers, which are also often conductors of electrical charge.
A method for manufacturing a photovoltaic module may include forming a photovoltaic device including a constituent material; forming a hydrophilic material adjacent to the constituent material, where the hydrophilic material includes an acrylate-based polymer; and depositing a remediation agent adjacent to the hydrophilic material, such that the remediation agent is proximate to, but not contacting the constituent material.
The method may have various optional features. For example, the hydrophilic material may include an acrylate-based polymer, such as, for example, a polyacrylate and/or a polymethacrylate. The hydrophilic material may include any mixture or copolymer including a polymerized polymethacrylate or an acrylate. The hydrophilic material may include a resin or a polymer. The polymer may include aminoalkyl methacrylate copolymers, aminoalkyl acrylate copolymers, methacrylic copolymers, acrylic copolymers, hydroxyalkyl methacrylate copolymers, hydroxyalkyl acrylate copolymers, glycol methacrylate copolymers, glycol acrylate copolymers, or any combinations thereof. The constituent material may include a heavy metal, for example, cadmium. The constituent material may include a semiconductor absorber layer on a semiconductor window layer. The constituent material may include a cadmium telluride layer on a cadmium sulfide layer. The remediation agent may include a precipitating agent, a complexing agent, a sorbent, or a stabilization agent. The precipitating agent may include a sulfide, hydroxide, carbonate, phosphate, or silicate. For example, the precipitating agent may include a calcium carbonate, calcium hydroxide, calcium phosphate, or calcium sulfide. The complexing agent may include a nitrogen-containing group, a sulfur-containing group, a phosphorus-containing group, an acid, or a carbonyl group. For example, the complexing agent may include EDTA, cysteine, xanthates, or trimercaptotriazine. The complexing agent may include an ion exchange resin, beads, or membrane. The sorbent may include zeolites, metal oxides, zero valent iron, carbon, tannin-rich materials, modified natural fibers, and modified synthetic fibers. The sorbent may include an apatite, a clay, or an oxide. The stabilization agent may include a cementious material. The step of forming a hydrophilic material may include contacting the hydrophilic material to the constituent material. The step of forming a hydrophilic material may include encapsulating the remediation agent within the hydrophilic material. The step of forming a hydrophilic material may include depositing the hydrophilic material in the laser scribes of a heavy metal. The step of forming a hydrophilic material may include spin coating. The step of forming a hydrophilic material may include placing a free-standing film. The step of forming a hydrophilic material may include placing an extruded film. The hydrophilic material may be part of a base chain of a polymeric adhesive or interlayer material. The step of forming a hydrophilic material may include dispersing the hydrophilic material throughout an interlayer near a polymer-metal interface. The method may include laminating one or more layers, where the photovoltaic module includes the one or more layers.
A photovoltaic module may include a photovoltaic device including a constituent material; a remediation agent proximate to the constituent material, where the remediation agent is capable of remediating the constituent material; and a hydrophilic material positioned between the constituent material and the remediation agent, where the hydrophilic material includes an acrylate-based polymer.
The photovoltaic module may have various optional features. For example, the hydrophilic material may include an acrylate-based polymer, such as, for example, a polyacrylate and/or a polymethacrylate. The hydrophilic material may include any mixture or copolymer including a polymerized polymethacrylate or an acrylate. The hydrophilic material may include a resin or a polymer. The polymer may include aminoalkyl methacrylate copolymers, aminoalkyl acrylate copolymers, methacrylic copolymers, acrylic copolymers, hydroxyalkyl methacrylate copolymers, hydroxyalkyl acrylate copolymers, glycol methacrylate copolymers, glycol acrylate copolymers, or any combinations thereof. The constituent material may include a heavy metal, for example, cadmium. The constituent material may include a semiconductor absorber layer on a semiconductor window layer. The constituent material may include a cadmium telluride layer on a cadmium sulfide layer. The remediation agent may include a precipitating agent, a complexing agent, a sorbent, or a stabilization agent. The precipitating agent may include a sulfide, hydroxide, carbonate, phosphate, or silicate. For example, the precipitating agent may include a calcium carbonate, calcium hydroxide, calcium phosphate, or calcium sulfide. The complexing agent may include a nitrogen-containing group, a sulfur-containing group, a phosphorus-containing group, an acid, or a carbonyl group. For example, the complexing agent may include EDTA, cysteine, xanthates, or trimercaptotriazine. The complexing agent may include an ion exchange resin, beads, or membrane. The sorbent may include zeolites, metal oxides, zero valent iron, carbon, tannin-rich materials, modified natural fibers, and modified synthetic fibers. The sorbent may include an apatite, a clay, or an oxide. The stabilization agent may include a cementious material. The hydrophilic material may be part of a base chain of a polymeric adhesive or interlayer material.
A photovoltaic module can include a transparent conductive oxide layer adjacent to a substrate and layers of semiconductor material. The layers of semiconductor material can include a bi-layer, which may include an n-type semiconductor window layer, and a p-type semiconductor absorber layer. The n-type window layer and the p-type absorber layer may be positioned in contact with one another to create an electric field. Photons can free electron-hole pairs upon making contact with the n-type window layer, sending electrons to the n side and holes to the p side. Electrons can flow back to the p side via an external current path. The resulting electron flow provides current, which combined with the resulting voltage from the electric field, creates power. The result is the conversion of photon energy into electric power. To preserve and enhance device performance, numerous layers can be positioned above the substrate in addition to the semiconductor window and absorber layers.
The cadmium telluride thin film layer (and other cadmium-containing layers) can be positioned proximate to materials designed to seal and hold the module together for many years and under a variety of conditions. These remediation agents can help retain heavy metals present within the module by forming low solubility compounds that immobilize, chelate, adsorb, and/or fixate the cadmium and/or other heavy metals within the structure of the module to assist with handling and disposal. A hydrophilic barrier can be positioned adjacent to the remediation agent to prevent direct contact between the remediation agent and a constituent material (i.e., a heavy metal). For example, a photovoltaic module may include a remediation agent partially or completely encapsulated within a hydrophilic barrier, where the hydrophilic barrier is positioned proximate to a heavy metal. Upon contacting water, the hydrophilic barrier may swell or dissolve, releasing the remediation agent to interact with the heavy metal (i.e., to immobilize, chelate, adsorb, and/or fixate the heavy metal within the module). The hydrophilic barrier may include an acrylate-based polymer, such as, for example, a polyacrylate and/or a polymethacrylate. The hydrophilic material may include any mixture or copolymer including a polymerized polymethacrylate or an acrylate. The hydrophilic material may include a resin or a polymer. The polymer may include aminoalkyl methacrylate copolymers, aminoalkyl acrylate copolymers, methacrylic copolymers, acrylic copolymers, hydroxyalkyl methacrylate copolymers, hydroxyalkyl acrylate copolymers, glycol methacrylate copolymers, glycol acrylate copolymers, or any combinations thereof. The hydrophilic barrier may be sensitive to pH, and may swell or dissolve only at certain pH levels.
Referring to
Heavy metal-immobilizing agent 120 can include any suitable remediation material, including, for example, a precipitating agent, a complexing agent, a sorbent, or a stabilizing agent. The precipitating agent can include various suitable materials, including, for example, FeS, Na2S, CaS, Ca(OH)2, NaOH, CaHPO4, Ca(H2PO4)2, CaCO3, CaSiO3, or combinations thereof. The complexing agent can include various suitable materials. For example, the complexing agent can include any suitable imino group, thiol group, disulfide, carbamate, or acid group. Examples may include, but are not limited to, EDTA, cysteine, xanthates, trimercaptotriazines, di-n-propyldithiophosphates, or any combinations or mixtures thereof. Possible sorbents include, but are not limited to, zeolites (synthetic or natural, or modified or non-modified), lignin, chitosan, dead biomass, fly ash, clay, apatite, metal oxides (hydrous or non-hydrous), zero valent iron, carbon, tannin-rich materials, or combinations or mixtures thereof. The stabilization material can include a cementious material such as pozzolan. Photovoltaic module 101 can include one or more interlayers 138, positioned adjacent to layer(s) 110 and front and back supports 100 and 130. Hydrophilic material 150 can be deposited within the laser scribes of any of layer(s) 110, or on either side of the front and back supports, with heavy metal-immobilizing agent 120 deposited thereon.
Heavy metal-immobilizing agent 120 may be incorporated into hydrophilic material 150 using any suitable technique and in any suitable spatial orientation. For example, heavy metal-immobilizing agent 120 may be dispersed in a uniform manner or in a concentration gradient within hydrophilic material 150. Heavy metal-immobilizing agent 120 may be sandwiched between layers of hydrophilic material 150, or partially or completely encapsulated within hydrophilic material 150. Referring to
Referring to
Hydrophilic material 150 can be deposited using any suitable technique, including, for example, spin coating, as well as placement of free-standing or extruded films. For example, hydrophilic material 150 can be patterned onto the surface of cadmium telluride layer 340, back contact metal 350, interlayer 138, or back support 130. Hydrophilic material 150 can be sprayed onto the cadmium telluride layer 340, back contact metal 350, interlayer 138, or back support prior to interlayer placement or lamination. The spray solution can be solvent-based, or it can be water-based; and the viscosity of the solution can be adjusted to achieve a suitable level of viscosity for spray and/or screen-printed application. Hydrophilic material 150 can be screen-printed onto the cadmium telluride layer 340, back contact metal 350, interlayer 138, or back support 130 prior to interlayer placement or lamination. Hydrophilic material 150 can undergo a drying process. Photovoltaic module 301 can be encapsulated in frame 400 from
A heavy metal-immobilizing agent can also be suitable for immobilizing other heavy metals present within the module, including cord plate solder. For example, referring to
Photovoltaic devices/modules fabricated using the methods discussed herein may be incorporated into one or more photovoltaic arrays. The arrays may be incorporated into various systems for generating electricity. For example, a photovoltaic module may be illuminated with a beam of light to generate a photocurrent. The photocurrent may be collected and converted from direct current (DC) to alternating current (AC) and distributed to a power grid. Light of any suitable wavelength may be directed at the module to produce the photocurrent, including, for example, more than 400 nm, or less than 700 nm (e.g., ultraviolet light). Photocurrent generated from one photovoltaic module may be combined with photocurrent generated from other photovoltaic modules. For example, the photovoltaic modules may be part of a photovoltaic array, from which the aggregate current may be harnessed and distributed.
The embodiments described above are offered by way of illustration and example. It should be understood that the examples provided above may be altered in certain respects and still remain within the scope of the claims. It should be appreciated that, while the invention has been described with reference to the above preferred embodiments, other embodiments are within the scope of the claims.
This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 61/247,920 filed on Oct. 1, 2009, which is hereby incorporated by reference.
Number | Date | Country | |
---|---|---|---|
61247920 | Oct 2009 | US |