BR102019001956B1 - PHOTOVOLTAIC CELL AND ENCAPSULATED PHOTOVOLTAIC CELL MANUFACTURING PROCESS - Google Patents

Abstract

PHOTOVOLTAIC CELL, MANUFACTURING PROCESS OF ENCAPSULATED PHOTOVOLTAIC CELL AND PHOTOVOLTAIC TILE A p-n-type photovoltaic cell (10) is described, comprising a crystalline silicon structure (11) coated with a conductive film (12) formed from a p-type dopant solution and an n-type dopant solution, the p-type and n-type dopant solutions comprising carotenoid components. Also described is a process of manufacturing a p-n-type photovoltaic cell encapsulated from a p-n-type photovoltaic cell (10) and the use of these encapsulated photovoltaic cells (19) forming modules (15) that are used to form, with photovoltaic tiles ( 20), unique pieces with the functions of coverage and electric power generation.

Description

[001] The present invention refers to a p-n-type photovoltaic cell, containing agents that provide a sun protection factor to reduce the thermal coefficient and, consequently, better efficiency in electrical conductivity. The invention further relates to the manufacturing process of this encapsulated photovoltaic cell and the photovoltaic tile comprising encapsulated photovoltaic cells.

Description of the state of the art

[002] Photovoltaic cells are devices made of semiconductor materials, which convert solar radiation into electrical energy, through the photoelectric effect.

[003] Several types of photovoltaic cells are known from the state of the art. They differ from each other by the material from which they are made, the most common being crystalline silicon, although other nobler materials with greater pecuniary value are also adopted in the manufacture of this device, such as tin/indium oxide ( OEI) coated with nanoparticles of titanium dioxide (TiO2) and zinc oxide (ZnO).

[004] Despite being considered a “clean” power generation device and, for this reason, there is a great interest in its use on a large scale, photovoltaic cells, because they are made of semiconductor materials, have, in general, low energy efficiency. due to two main factors: (i) the excess of solar energy absorbed by these semiconductor materials, mainly energy from the ultraviolet spectrum, which leads to an increase in cell temperature resulting in a reduction in electrical conductivity; and (ii) the infrared spectrum also absorbed by the semiconductor material of the cell in the form of solar radiation and which does not hold enough energy for electrical conductivity, resulting in simple heat conversion that increases the temperature of the cell and results in the reduction of electrical conductivity.

[005] In order to solve the problem of low electrical conductivity, several studies and developments in this technological area are being made.

[006] In this sense, the document BR 10 2012 027389-6 describes tiles in Roman tile model or Plan model that comprise crystalline silicon photovoltaic cells doped with phosphorus and encapsulated in their structure forming a single piece. The assembled tile comprises, from the top to the bottom surface, layers of translucent resin, ethylene vinyl acetate (EVA) polymer, photovoltaic cell, EVA polymer as a backsheet layer, tile and translucent resin.

[007] Also, the document by Gao et al., entitled “Photovoltaic response of carotenoid-sensitized electrode in aqueous solution: ITO coated with a mixture of TiO2 nanoparticles, carotenoid, and polyvinylcarbazole”, for example, describes the treatment of semiconductors of tin/indium oxide coated with titanium dioxide nanoparticles (OEI/TiO2) with carotenoids based on canthaxanthin and β-carotene to improve the efficiency of these semiconductor materials. This document also teaches the mechanism of action of carotenoids in this type of treatment. In this context, the canthaxanthin molecules present in these semiconductors absorb solar radiation, becoming energetically excited. In this situation, its electrons are donated to the tin/indium oxide conduction band with TiO2, optimizing its electrical conductivity.

[008] Also the paper by Zhuang et al., entitled “Natural-photosynthesis-inspired photovoltaic cells using carotenoid aggregates as electron donors, and chlorophyll derivatives as electron acceptors” reveals the treatment of tin/indium oxide (OEI) photovoltaic cells. and molybdenum (III) oxide (MoO3), or OEI/MoO3, with lycopene-based carotenoids and chlorophyll pigments. This document also teaches the process of optimizing energy efficiency due to the presence of carotenoids, which act as electron donating molecules, and chlorophyll, acting as an electron acceptor molecule. The presence of these molecules creates a balance of holes and electronic flow in these photovoltaic cells, improving their efficiency.

[009] The document by Muthusaamy, entitled “Marine seaweed Sargassum wightii extract as a low-cost sensitizer for ZnO photoanode based dye-sensitized solar cell” describes the use of seaweed extract comprising a mixture of pigments such as carotenoids, fucoxanthin and chlorophyll, to increase the energy efficiency of zinc oxide (ZnO) photoanodes, a type of semiconductor. In this document, the presence of these pigments improves the photovoltaic efficiency of this material.

[010] Thus, it is possible to find in the state of the art researches that make use of carotenoids in undoped photovoltaic cells, as well as p-n-type photovoltaic cells (doped with p-type and n-type dopants), but which do not comprise carotenoids.

Objectives of the invention

[011] Thus, the present invention aims to provide a p-n-type photovoltaic cell, which comprises p-type and n-type dopants and agents that provide a sun protection factor to reduce the thermal coefficient, attributing to this photovoltaic cell an increase in conductivity and increased efficiency in this electrical conductivity, respectively.

[012] Another objective of this invention is to provide a process for manufacturing a p-n encapsulated photovoltaic cell, comprising doping steps containing agents that provide a sun protection factor to reduce the thermal coefficient and, consequently, increase the efficiency in the electrical conductivity of this cell.

[013] It is also an objective of the present invention to provide a photovoltaic tile, forming a single piece with the encapsulated photovoltaic cells in order to understand coverage and energy generation properties simultaneously.

Brief description of the invention

[014] The object of the present invention is a p-n-type photovoltaic cell, comprising a crystalline silicon structure coated by a conductive film formed from a p-type dopant solution and an n-type dopant solution, the dopant solutions of the type p and n-type comprising carotenoid components.

[015] Another object of this invention is a process for manufacturing a p-n encapsulated photovoltaic cell, comprising the following steps: a) coating a plurality of crystalline silicon structures by a conductive film formed from p-type and n-type comprising carotenoid components, forming a plurality of p-n-type photovoltaic cells; b) joining the plurality of p-n-type photovoltaic cells by means of tin solder forming a module; c) encapsulation of the module forming an encapsulated photovoltaic cell; and d) electrical connection.

Brief description of the drawings

[16] Figure 1A - is a schematic sectional view of the p-n type photovoltaic cell object of the present invention;

[17] Figure 1B - is a schematic view of a plurality of p-n type photovoltaic cells associated with each other;

[18] Figure 2 - is a perspective view of a photovoltaic tile;

[19] Figure 3 - is a flowchart of the encapsulated photovoltaic cell manufacturing process, object of this invention;

[20] Figure 4 - is a flowchart of the step of the manufacturing process of the encapsulated photovoltaic cell, more specifically of the step of coating a plurality of crystalline silicon structures by a conductive film; and

[21] Figure 5 - is a schematic exploded view of the encapsulated photovoltaic cell.

Detailed description of the invention

[22] According to a preferred embodiment and as illustrated in figures 1A and 1B, the p-n type photovoltaic cell 10, object of this invention, comprises a crystalline silicon structure 11 which is coated with a conductive film 12 formed from a p-type dopant solution and an n-type dopant solution.

[23] The p-type and n-type doping solutions comprise, in addition to the doping elements, carotenoid components as described in detail below.

[24] In this sense, the n-type dopant solution comprises a dopant element from group 5A of the periodic table, preferably phosphorus, in an amount of 1.5 to 4% by mass. The p-type dopant solution comprises a dopant element from group 2A of the periodic table, preferably calcium, in an amount of 0.5 to 2% by mass.

[025] The p-type and n-type doping solutions also comprise isopropyl alcohol in an amount of 50% to 70% by mass, rosin resin in an amount of 15 to 30% by mass, cationic fluorocarbon surfactant in an amount of 0, 5 to 2% by mass, liquid glycerin in an amount of 0.5 to 2.5% by mass and silver nitrate in an amount of 1.5 to 4% by mass.

[026] Still, for the formation of the conductive film 12, the p-type and n-type doping solutions comprise carotenoids in an amount of 1 to 5% by mass, in each solution. Carotenoids consist of natural pigments, with high absorption capacity of solar radiation, also acting as an ultraviolet filter. Such carotenoids are preferably selected from a group comprising bixin, norbixin, lycopene, canthaxanthin, fucoxanthin and beta-carotene.

[027] A photovoltaic cell of the p-n 10 type, when suffering the incidence of sunlight, will produce an electric current. The silicon atom present in the crystalline silicon 11 structure has exactly four electrons in its last electron shell. Phosphorus, present in conductive film 12, as an n-type dopant element, has five electrons, so phosphorus atoms will have four of their shared electrons, leaving an electron that is not part of a covalent bond, but is still attracted to the charge. positive for the phosphorus nucleus. Thus, the phosphorus electrons that are not part of a covalent bond can easily break their bond with the phosphorus nucleus, with a low energy requirement. In this case, these electrons are considered free and the crystalline silicon structure 11, doped by the n-type dopant element present in the conductive film 12, now has an n-type electronic layer.

[028] Calcium, in turn, has two electrons in the last electron shell and, therefore, when replacing a silicon atom, they will form a "hole" that will be defined as the absence of two negative charges, forming the p-type electronic shell. .

[029] By placing the two electronic layers, n-type and p-type, in contact, electrons flow from regions of low electronic concentration to regions of high electronic concentration. When electrons leave the n-type side, an accumulation of positive charge occurs at the boundary of the p-n contact, similarly an accumulation of negative charge occurs on the p-type side. This charge imbalance that occurs at the boundary of the p-n type connection will be responsible for the emergence of an electric field that will oppose the natural tendency of the diffusion of electrons and holes and, thus, an equilibrium situation will be reached.

[030] When the sunlight formed by photons falls on the p-n-type photovoltaic cell, there will be the formation of electron-hole pairs. For every photon that has enough energy to make electrons flow from one electron shell to the other, an electron and a hole will form. Under these conditions the electrons produced will flow to the n-type side and the holes will go to the p-type side and this flow of electrons will be responsible for the emergence of an electric current. As the electric field of the cell will provide the potential difference, it will be possible to generate power, which is exactly the product of these two physical quantities.

[031] Photons with energy higher than that needed to make electrons flow from one electronic layer to another, that is, photons holding energy near the ultraviolet light region, with a higher frequency, grant excess energy that will be transformed into heat. Likewise, photons with energy lower than that needed to make electrons flow from one electronic layer to another, i.e., photons holding energy near the infrared light region, with lower frequency, do not provide sufficient energy for the release of electrons. from its orbit and, as a result, this energy is converted into heat.

[032] In these two situations described above, the heat generated causes the p-n 1O type photovoltaic cells with crystalline silicon 11 structure to lose efficiency, as the cell voltage is reduced and, therefore, the power it can generate is also reduced. reduces.

[033] With the presence of carotenoids in p-type and conductive film-type 12 doping solutions, the efficiency of the p-n-type 10 photovoltaic cell is increased. This is because carotenoids help in the absorption of sunlight and, in addition, have a high absorption capacity for solar radiation, especially ultraviolet radiation.

[034] By absorbing the excess energy produced by ultraviolet rays, carotenoids avoid the generation of heat in the p-n 10 photovoltaic cell and also absorb excess energy in the ultraviolet region, forming a new electronic flux directed to the bands of conduction of the p-n type photovoltaic cell 10. More specifically, the electrons of the carotenoid molecule itself are transferred to the said conduction band, consequently, the electric current increases and with that, the power of the cell 10 is increased.

[035] In order to have a photovoltaic system, as illustrated in Figure 1A, it is necessary to build modules that consist of the union of a plurality of photovoltaic cells of the p-n type 10, where this union is made through tin solder 13. To avoid problems in the weld region 13, the cell 10 needs to be free of impurities, mainly in this junction region. Thus, isopropyl alcohol added to p-type and n-type doping solutions provides for the elimination of impurities that may interfere with the electrical conductivity of the cell 10 and the complete elimination of residual water.

[036] In addition, the rosin resin and glycerin work so that the solder spreads evenly. Thus, at the time of soldering, the tin is freely anchored on the parts to be soldered. Silver nitrate, on the other hand, is an excellent energy conductor and is present in p-type and n-type doping solutions to improve energy performance in the cell junction region 10.

[037] Consequently, the presence of the tin solder 13 at the junction of a plurality of p-n type photovoltaic cells 10 provides the electrical conductivity between the cells 10 joined, avoiding, for example, regions of electrical isolation that impact the generation of electrical energy. electricity.

[038] It is also an object of this invention, a process for manufacturing encapsulated p-n type photovoltaic cell 10, as illustrated in figure 3. This process comprises the following steps: a) coating a plurality of crystalline silicon structures 11 by a film conductor 12 formed from p-type and n-type doping solutions comprising carotenoid components, forming a plurality of p-n-type photovoltaic cells 10; b) joining the plurality of p-n type photovoltaic cells 10 by means of tin solder 13 forming a module 15; c) encapsulation of the module 15 forming an encapsulated photovoltaic cell 19; and d) electrical connection.

a) Coating stage

[039] The step of coating a plurality of crystalline silicon structures 11 by a conductive film 12 formed from p-type and n-type doping solutions comprises a mixture of one part rosin resin to three parts of isopropyl alcohol forming a mixture A, addition of one part carotenoids to sixteen parts of mixture A forming a homogeneous mixture B, addition of one part cationic fluorocarbon surfactant to eighty-five parts of mixture B and three parts of silver nitrate to one part of cationic fluorocarbon surfactant forming a mixture C and adding one part of glycerin for every forty-four parts of mixture C forming a mixture D (figure 4).

[040] Once the mixture D is formed, it is separated into mixture D1 and mixture D2, in equal parts. In the D1 mixture, the step of adding one part of phosphorus to fifteen parts of the D1 mixture takes place, forming the n-type dopant solution. In mixture D2, the step of adding one part of calcium to forty-five and a half parts of mixture D2 takes place, forming the p-type dopant solution.

[041] Next, the crystalline silicon structures 11 are immersed in the p-type dopant solution and, subsequently, immersed in the n-type dopant solution, according to route 1 in figure 4. Optionally, the crystalline silicon structures 11 can be immersed in the n-type dopant solution and then immersed in the p-type dopant solution, according to route 2 in figure 4. At the end of this step, the p-n type 10 photovoltaic cells are obtained, which are then taken to the final step drying process to form the conductive film 12.

b) Step of joining the plurality of p-n type photovoltaic cells

[042] In this step, a plurality of p-n type photovoltaic cells 10 is positioned in series forming a grouping of at least seven cells 10, which will be joined to form a module 15 (Figure 1B).

[043] The union is made by soldering tin 13 in order to allow the union region not to compromise the electrical conductivity of module 15.

c) Module encapsulation step

[044] The formed module 15 is then encapsulated. As illustrated in figure 5, initially, above the module 15, a first layer of EVA polymer 16 is positioned forming the negative side. Below the module 15, a second layer of EVA polymer 17 is positioned, followed by a protective backing layer 18 of TPT (Tedlar Polyester Tedlar) material, forming a positive side.

[045] After positioning these layers above and below the module 15, the encapsulation is carried out, which consists of submitting this set to vacuum in a lamination equipment. This encapsulation provides corrosion protection and waterproofing.

[046] Finally, the encapsulated set is subjected to a resin coating that consists of applying a layer of resin, for example translucent epoxy resin, on the negative part formed by the first layer of EVA polymer 16, forming a resin layer 14.

[047] The result of this step is an encapsulated photovoltaic cell 19.

d) electrical connection

[048] The encapsulated photovoltaic cell 19 receives a junction box (not shown) positioned on the external surface of the protective background layer 18. This junction box is intended to allow the connection of the encapsulated photovoltaic cell 19 to a current converter ( not illustrated) during use.

[049] Another object of this invention consists of a photovoltaic tile 20, illustrated in figure 2. The photovoltaic tile 20 is preferably made of concrete or fiber cement, and may also be of other materials such as ceramics and polymers, and receives a plurality of encapsulated photovoltaic cells 19, in order to form a photovoltaic system.

[050] The photovoltaic tile 20 can have a wavy shape, containing at least one undulation 21 followed by at least one plateau 22, a wavy shape 21 without the presence of plateaus or other numerous formats. The encapsulated photovoltaic cells 19 are fixed to the tiles 20, preferably by gluing with polyurethane glue, and other types of fixation can be used, such as adhesives, screws, rivets, among others, so that the encapsulated photovoltaic cells 19 form , with the photovoltaic tile 20, unique pieces containing two functions: coverage and electricity generation. For this, they do not require a fastening system with aluminum profiles and extra structures to be fixed on the roofs for the photovoltaic system, just the usual wood or metal structure of roofs, since the tile itself to be used as a cover already comprises photovoltaic cells. in its constitution.

[051] Particularly, the encapsulated photovoltaic cells 19 can be fixed on the plateaus 22 of the photovoltaic tile 20, on the corrugations 21 of the photovoltaic tile 20, in valleys (not shown) formed between two subsequent corrugations 21, on the side walls of the corrugations 21, or other points on the surface of the PV tile 20.

[052] Photovoltaic tile 20 solves the aesthetic-functional problem of conventional photovoltaic panels, solves fixing problems, facilitates installation and maintenance on the roof, increases the durability of the roof, allows the installation of a photovoltaic system in projects where there are restrictions on the adding weight to the roof structure and reducing the use of materials, reducing the cost of a photovoltaic system.

[053] Having described a preferred example of embodiment, it should be understood that the scope of the present invention encompasses other possible variations, being limited only by the content of the appended claims, including the possible equivalents.

Claims (8)

1. p-n-type photovoltaic cell (10), comprising a crystalline silicon structure (11) coated with a conductive film (12) formed from a p-type dopant solution and an n-type dopant solution, the type photovoltaic cell p-n (10) being characterized by the conductive film (12) being formed by p-type and n-type doping solutions that comprise carotenoid components that provide a sun protection factor to decrease the thermal coefficient and increase the electrical conductivity of the cell (10). 2. Photovoltaic cell, according to claim 1, characterized in that the p-type dopant solution comprises a dopant element of group 5A and the n-type dopant solution comprises a dopant element of group 2A of the periodic table. 3. Photovoltaic cell, according to claim 2, characterized in that the dopant of group 5A is phosphorus in an amount of 1.5 to 4% and the dopant of group 2A is calcium in an amount of 0.5 to two%. 4. Photovoltaic cell, according to claim 2, characterized in that the p-type doping solution and the n-type solution also comprise rosin resin in an amount of 15 to 30% by weight, fluorocarbon cationic surfactant in an amount of 0.5 to 2%, liquid glycerin in an amount of 0.5 to 2.5% and silver nitrate in an amount of 1.5 to 4%. 5. Photovoltaic cell, according to claims 1 to 4, characterized in that carotenoids are present in the p-type dopant solution and in the n-type dopant solution in an amount of 1 to 5% by weight in each solution. 6. Photovoltaic cell, according to claim 5, characterized in that the carotenoids are selected from a group comprising bixin, norbixin, lycopene, canthaxanthin, fucoxanthin and beta-carotene. 7. Process of manufacturing a p-n encapsulated photovoltaic cell, characterized in that it comprises the following step: a) coating a plurality of crystalline silicon structures (11) by a conductive film (12) formed from doping solutions p-type and n-type comprising carotenoid components that provide a sun protection factor to decrease the thermal coefficient, resulting in a plurality of p-n-type photovoltaic cells (10). 8. Process according to claim 7, characterized in that the step of coating a plurality of crystalline silicon structures (11) by a conductive film (12) comprises the following steps: (i) mixing of rosin resin and isopropyl alcohol forming a mixture A; (ii) addition of carotenoids in mixture A forming a homogeneous mixture B; (iii) adding cationic fluorocarbon surfactant and silver nitrate to mixture B forming mixture C; (iv) adding glycerin to mixture C forming a mixture D; (v) separating mixture D into mixtures D1 and D2, adding phosphorus to mixture D1 forming the n-type dopant solution and adding calcium to mixture D2 forming the p-type dopant solution; (vi) immersing the plurality of crystalline silicon structures (11) in the p-type and n-type doping solutions forming p-n-type photovoltaic cells (10); (vii) drying the p-n type photovoltaic cells (10) forming the conductive film (12).

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