ROOF PANEL HAVING SOLAR CELL

A roof panel for a vehicle that has a solar cell is provided. Specifically, a solar cell panel that has a plurality of solar cell modules electrically connected is disposed on an inner surface of an upper surface of a vehicle body and a sticking member that protects the solar cell panel from an impact while having sticking characteristics is inserted and laminated between the inner surface of the upper surface of the vehicle body and the solar cell panel.

It should be understood that the accompanying drawings are not necessarily to scale, presenting a somewhat simplified representation of various exemplary features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment. In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. In a description of the exemplary embodiments of the present invention, the sizes of constituent elements may be exaggerated for clarity, and do not represent the actual sizes of the elements.

In the description of the exemplary embodiments of the present invention, a dye-sensitized solar cell will be basically described but is a simple example, and any solar cell that may be mounted to a support forming a general roof panel constituting an upper surface of a vehicle body or a roof panel such as glass of a sunroof/panorama roof may be applied to the present invention. In addition, any device that employs a smart window such as Electrochromic (EC), Polymer Dispersed Liquid Crystal (PDLC) and Suspended Particle Display (SPD) or a transparent electrode substrate or may be mounted to a vehicle, including an organic solar cell may be applied to the present invention.

Although a grid type parallel solar cell module in which cells are connected in parallel is illustrated, a monolithic structure in which photonic electrodes and catalytic electrodes of cells are formed in one substrate, a Z-type structure in which cells are connected in series, and a W-type structure in which photonic electrodes and catalytic electrodes are alternately formed in one substrate may be applied to the present invention in addition.

In the following description, inserting a metallic collector electrode is referred to as a module, and a solar cell in which such modules are connected in series or in parallel is referred to as a panel.

FIG. 1is an exemplary sectional view showing a dye-sensitized solar cell that may be applied to a roof panel for a vehicle, and shows a basic configuration and structure of a parallel solar cell module in which cells may be connected in parallel. As shown, the dye-sensitized solar cell module unit cell) may include a working electrode10in which photonic electrodes to which a dye is adsorbed may be laminated, a counter electrode20in which catalytic electrodes23may be laminated, and an electrolyte17filled in a sealing space between the working electrode10and the counter electrode20, and the working electrode10and the counter electrode20may be bonded with the electrolyte17therebetween. In particular, the working electrode10and the counter electrode20may include transparent substrates11and21on which transparent conductive oxides12and22such as Fluorine doped Tin Oxide (FTO), respectively to cause the generated photons to move.

In an interior of the solar cell module, that is, inside the space between the working electrode10and the counter electrode20, a dye (not shown) may be disposed to absorb absorbing light and emit electrons, a photonic electrode (or a semiconductor oxide thin film)13such as titanium dioxide (TiO2) may be laminated on the transparent conductive layer12of the transparent substrate11in the working electrode10, and an electrolyte17may be disposed to fill electrons in the dye from which electrons are emitted.

A dye (e.g., a Ruthenium (Ru) based dye) that absorbs light may be adsorbed to a surface of the photonic electrode13, which may include porous nano particles to move emitted electrons to an external electrode. A catalytic electrode23may be laminated on the transparent conductive layer22of the transparent substrate21in the counter electrode20, and the counter electrode20that includes the catalytic electrode23may reduce the oxidized electrolyte17. The catalytic electrode23may be a platinum (Pt) electrode operating as a catalytic, and may be located between metal electrode protection layers25. A dye-sensitized solar cell module may be configured by filling the electrolyte17(e.g., an I−/I3−based electrolyte) in a space between electrodes sealed by a sealant16while the working electrode10and the counter electrode20are bonded to each other.

Further, since collection efficiency may deteriorate due to the resistance of the transparent conductive layer12and22when a size of the solar cell increases, the metallic collector electrodes14and24may be additionally inserted to compensate for the problem, and collector electrode protection layers15and25may be formed to prevent corrosion of the metallic collector electrodes14and24by the electrolyte.

As described above, the solar cell panel may be configured by inserting the metal collector electrodes14and24into solar cell modules and electrically connecting the solar cell modules in series or in parallel. The present invention provides a method and a structure for mounting a solar cell panel to an upper surface of a vehicle body, and a roof panel for a vehicle may be configured by attaching a solar cell panel to reinforcing glass of a sunroof or a panorama roof forming an upper surface of a vehicle body.

Further, the present invention provides a structure of improving an anti-impact strength of a solar cell roof panel for a vehicle, and a roof panel for a vehicle may be configured by inserting and stacking a sticking member that protects a solar cell panel from an external impact while maintaining sticking characteristics between tempered glass and a solar cell panel when the solar cell panel (or solar cell module) is disposed on an interior side of the vehicle, that is, on an inner surface of the tempered glass of a sunroof or a panorama roof

In applying the solar cell panel to the roof panel for a vehicle, the types of the transparent substrates11and21used for the working electrode10and the counter electrode20of the solar cell are not specifically limited according to an exemplary embodiment of the present invention, and may be a glass material for a solar cell such as soda lime glass, low-iron glass, or alkali-free glass or may be a known chemical tempered glass, heat strengthened glass, tempered glass, or general glass according to other characteristics thereof. In the present invention, a thickness of glass used for the transparent substrate11and21is not specifically limited, and ranges from ultra-thin glass that have a thickness of about 0.1 mm and glass of a thickness of several meters to be utilized according to their characteristics.

Moreover, considering that the solar cell panel may be attached to an interior side of the vehicle, when the substrate11and21is glass, glass of a minimal thickness may be used to maximize interior space, and a thickness of the solar cell panel may be decreased by using a thin film transparent substrate to minimize an increase in weight.

Soda lime glass may be used as a transparent substrate of a general dye-sensitized solar cell or specially made glass such as low-iron glass and alkali-free glass may be used to increase light transmission. Most of the glass transparent substrates generally have a thickness of about 2 mm or greater to endure an external impact, and have a minimum thickness of about 4 mm when a solar cell panel is manufactured. Further, tempered glass may be used as a glass material used for a sunroof or a panorama roof of a vehicle to secure safety of a passenger, and a general thickness of the tempered glass is about 4 mm. Thus, when a general solar cell panel is mounted, a roof panel for a vehicle may have a minimum thickness of about 8 mm, which increases the weight of the vehicle and lowers fuel ratio. Therefore, a transparent substrate of a solar cell panel used for a roof panel of a vehicle may have decreased thickness and weight.

A dye-sensitized solar cell that uses a lightweight thin film transparent substrate that has a substantially thin thickness may be mounted to the solar cell roof panel of the present invention, and specifically a thin film transparent substrate that has an ultraviolet ray transmission of at least 80% may be used. In particular, the thin film transparent substrate of the dye sensitized solar cell panel in the roof panel for a vehicle according to the exemplary embodiment of the present invention may have a thickness of about 1 mm or less, and the solar cell panel that uses the thin film transparent substrate may have a decreased thickness and a weight compared to a conventional substrate and may have a decreased weight and flexible characteristics suitable for attachment to tempered glass of a roof panel for a vehicle having a curved structure.

In addition, ultra-thin film glass that has flexible characteristics may be used as a thin film transparent substrate to naturally harmonize with a curved portion having a predetermined curvature, such as a sunroof or a panorama roof of a vehicle. The ultra-thin film transparent substrate formed of ultra thin film glass is a substrate thinner than a general transparent substrate and a thin film transparent substrate, and may have a thickness of about 0.7 mm or less and more preferably, may have a thickness of about 0.1 mm to 0.5 mm. Among flexible substrates, the ultra thin film transparent substrate that has a thin thickness may be transparent and may have improved surface flatness, therefore a separately introduced packaging thin film against moisture or oxygen may be omitted. Further, manufacturing costs may be reduced and process efficiency may be secured.

When a solar cell panel is configured by applying the ultra thin film transparent substrate that has a substantially thin thickness to a working electrode and a counter electrode, an entire thickness of the solar cell panel may be reduced to a thickness of about 2 mm or less may be formed compared to a conventional transparent substrate that has a thickness of about 4 mm or greater. Further, the solar cell panel may be applied to the roof panel for a vehicle without changing the design of the vehicle, and manufacturing costs may be reduced.

Hereinafter, in the description of the exemplary embodiments of the present invention, the ultra thin film and thin film transparent substrates are thin film transparent substrates as the ultra thin film transparent substrate fall within the scope of the thin film transparent substrate.

A thin film plastic substrate of a polymer material may be applied as the thin film transparent substrate of the solar cell panel in addition to the glass substrate and a plastic substrate that has an ultraviolet ray transmission of at least 80% may be used. Further, for a plastic substrate, a transparent substrate that has a thickness of about 0.1 mm to 1 mm may be used.

The plastic substrate may be a substrate manufactured using any one selected from a polyethylene based polymer, a polypropylene based polymer, a polyester based polymer, a polyacryl based polymer, a polyimide based polymer, a polystyrene based polymer, a substrate made of a blend where polymer materials are mixed or a copolymer, or a substrate made by laminating polymer materials. In particular, for example, polycarbonate (PC), polyethersulfone (PES), cyclic olefin copolymer (COC), polyethylene (PE), polyethyleneterephthalate (PET), polyehtylenenaphthalate (PEN), triacetylcellulose (TAC), polyimide (PI), polymethylmethacrylate (PMMA), polyetheretherketone (PEEK), polyamide (PA), polyetherimide (PEI), polypropylene (PP), and polypropylene (OPP, oriented) may be used.

Moreover, when the thin film transparent substrate is applied, the substrate may be damaged by an external impact and thus a structure for protecting the substrate is necessary. Accordingly, a solar cell module or a solar cell panel in which a plurality of solar cell modules are electrically connected may be disposed on an inside surface of temperature glass of a sunroof or a panorama roof to form an upper surface of the vehicle body in a roof panel of a vehicle according to the exemplary embodiment of the present invention, and a sticking member that protects a solar cell panel from an external impact while having sticking characteristics may be stacked between tempered glass of a sunroof or a panorama roof and a solar cell module or a solar cell panel.

FIG. 2shows exemplary sectional views of roof panels for a vehicle according to various exemplary embodiments of the present invention, and shows the exemplary embodiments of the present invention in which a solar cell panel200may be disposed while a sticking member210is stuck to an inside surface of the upper surface (tempered glass)300of the vehicle body. In addition,FIG. 2shows the solar cell panel200while the elements ofFIG. 1are not illustrated for convenience. As shown inFIG. 1, in each of the modules of the solar cell panel200, the counter electrode20(seeFIG. 1) may be located below the working electrode10(seeFIG. 1) to attach the solar cell panel200while the sticking member210is stuck to an inside surface of the upper surface300of the vehicle body.

Further, althoughFIG. 2shows an exemplary curved shape of the solar cell panel200based on the curvature of the upper surface300of the vehicle body, a flat solar cell panel may be applied when the upper surface300of the vehicle body is not curved but flat. In section (a) ofFIG. 2a sticking member210may be interposed between an upper surface (e.g., glass of a sunroof or a panorama roof)300of the vehicle and the solar cell panel200and a finishing member220may be attached to an inner side of the solar cell panel200, in which the finishing member220may be attached to an outer surface of the counter electrode (e.g., the transparent substrate of the counter electrode)20(seeFIG. 1) of the solar cell panel200. In some cases, the finishing member220may be removed.

Further, the sticking member210may be made of a flexible and cushioning material, and the sticking member210may protect the solar cell panel200when an impact is applied from the exterior through a proper impact absorbing operation. Thus, the sticking member210may increase anti-impact strengths of the solar cell panel200and the roof panel as a whole.

The sticking member210is not specifically limited, but may be a sticking member using one or more complex materials selected from a group consisting of polydimethylsiloxane (PDMS), polysilazane, polysilsesquioxane (PSSQ), a polysilicon based polymer, a polyurethane polymer, an epoxy based polymer, a synthetic resin, a natural rubber, a modified elastomer, a polyacryl based polymer such as polymethylmethacrylate (PMMA), a styrene based copolymer and a styrene based thermosetting copolymer such as polystyrene (PS), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene triblock copolymer (SIS), styrene-etylene-butylene-styrene block copolymer (SEBS), and acrylonitrile-butadiene-styrene copolymer (ABS), and a cellulose composite such as methylcellulose, ethylcellulose, and buthylcellulose, and polyvinylbutyral (PVB), ethylene vinyl acetate (EVA), and a sticking member obtained by laminating members formed of the above-described materials.

In the exemplary embodiment of section (a) ofFIG. 2, a bonding film (e.g., finishing material)220may be formed on one surface which meets the counter electrode of the solar cell panel200to support the solar cell panel200, and the bonding layer may be coated on opposite surfaces of the sticking member210. The bonding film220may be obtained by forming a bonding layer on one surface of a polymer base, in which the base may be a film manufactured using a polymer material such as a polyethylene based polymer, a polypropylene based polymer, a polyester based polymer, a polyacryl based polymer, a polyimide based polymer, a polystyrene based polymer, may be a film formed of a blend where polymer materials are mixed or a copolymer, or a film obtained by laminating a plurality of polymer materials. However, the bonding film is not limited thereto.

The bonding layer of the bonding film may be formed using a material such as an epoxy based material, an acryl based material, a urethane based material, or a modified acryl based material, a modified urethane based material, and a modified elastomer based material, Further, after the bonding layer is formed at the working electrode and the counter electrode of the solar cell, the bonding layer may be bonded to the polymer base. In addition, instead of the bonding film, a support manufactured of a complex material in which PC (polycarbonate) or glass fibers are mixed, or EVA (Ethylene Vinyl Acetate), or glass, may be used, but any support formed of a material capable of supporting a solar cell or a sticking member may be used. In the present invention, the bonding film or the support will be referred to as a finishing member.

Section (h) ofFIG. 2shows an exemplary embodiment in which a sticking member210may be interposed between the solar cell panel200and the finishing member220as compared to section (a) ofFIG. 2. As shown, the sticking member210may be laminated on opposite surfaces of the solar cell panel200to surround the solar cell panel200in a sandwich type, and may prevent damage to the solar cell panel200due to an internal or external impact of the vehicle. In addition, section (c) ofFIG. 2shows an exemplary embodiment in which a thermoplastic or UV curing protection coating layer230giving a surface strength to increase an anti-scratch property may be coated on a surface of the finishing member220exposed to the interior of a vehicle as compared with the exemplary embodiments of sections (a) and (b) ofFIG. 2.

Table 1 is a simulation result obtained by calculating a maximum stress MPa applied to the solar cell substrate by an external impact when the sticking member using PDMS is applied, and soda lime thin film glass is used as the solar cell substrate.

It is known in the art that the soda lime glass may be damaged when the maximum stress is 50 MPa or higher, and Table 1 shows that the solar cell panel is not damaged when a PDMS sticking, member of a predetermined thickness is applied (e.g., a maximum stress of less than 50 MPa is generated).

Moreover, a bonding layer may be laminated on one surface or opposite surfaces of the sticking member to constitute the roof panel for a vehicle.FIG. 3is an exemplary sectional view showing a roof panel for a vehicle according to another exemplary embodiment of the present invention, and shows an exemplary embodiment in which the transparent bonding layer211is applied to opposite surfaces of the sticking member210.

Specifically, section (a) ofFIG. 3is an exemplary sectional view of the sticking member210in which the bonding layer211may be formed, and section (b) ofFIG. 3is an exemplary sectional view of a roof panel using the sticking member210of section (a) ofFIG. 3. The exemplary embodiment of section (b) ofFIG. 3may be different from the embodiment of sections (b) ofFIG. 2in that the bonding layer211may be additionally applied to opposite surfaces of the sticking member210. In addition to the configurations of the exemplary embodiments shown inFIG. 2a bonding layer211may be laminated on one surface or opposite surfaces of the sticking member210to constitute a roof panel.

When the transparent bonding layer211is bonded to the sticking member210, the sticking member210may be stably bonded and fixed between the upper surface300of the vehicle and the solar cell panel200(or the solar cell module), and between the solar cell panel200and the finishing member220by the transparent bonding layer211, and a bonding force between the sticking member210and the elements bonded to the sticking member210may be improved.

In addition, the sticking member210that has the transparent bonding layer211may be prepared while the release film212is attached on the bonding layer211for each treatment and process as shown in section (a) ofFIG. 3, wherein when the sticking member210is bonded to other elements such as the upper surface300of the vehicle body, the solar cell panel200, and the finishing member220, the release film212may be removed from the bonding layer211. The release film212may be manufactured from a general transparent film polymer material, and a highly releasing material such as a silicon based material or a fluorine based material may be coated on the release film to be released after being attached to the bonding layer to be used. An adhesive that may be used to form the bonding layer211may be an epoxy based material, an acryl based material, a urethane based material, a modified acryl based material, a modified urethane based material, or a modified elastomer based material. However, since the release film212may be a disposable film that protects a surface of the transparent bonding layer211, a film of a low-priced material such as polyester may be used.

Moreover,FIG. 4is an exemplary sectional view showing a roof panel according to another exemplary embodiment of the present invention. As shown, a scattering layer221may be additionally introduced to one surface of the solar cell panel protecting finishing member220that includes a transparent bonding film. When the scattering layer221is formed, light entering the solar cell panel200may be scattered in the solar cell panel and loss of light directly exiting to the exterior of the solar cell panel may be reduced, thereby increasing the efficiency of the solar cell. In other words, in the transparent bonding film which is the finishing member220, the scattering layer221that scatters light having entered the solar cell panel200to reduce loss of light and increase efficiency of the solar cell may be provided on one surface of the transparent bonding film bonded to a substrate (e.g., the solar cell module or an inner surface of the solar cell panel) of the counter electrode. The scattering layer221of the film may be obtained by forming a convexo-concave structure that has a triangular pyramid such as a saw-tooth shape as shown inFIG. 4, or various beads that have different sizes may be formed such that a non-uniform structure whose surface has different heights may be formed in the transparent bonding layer.

Although not shown in the drawings, a light reflecting layer, such as aluminum foil or a mirror, that reflects light may be formed on one surface (e.g., a surface attached to an outer surface of the substrate for the counter electrode) of the transparent bonding film, which may achieve the same effect as forming the scattering layer. However, since the transparent bonding film that has the light reflecting layer may lower a lighting property when applied to a sunroof of the vehicle.

FIG. 5is an exemplary view showing the solar cell module which has been described in the exemplary embodiments, and shows a surface of the solar cell module that has a parallel structure. In other words,FIG. 5is an exemplary view of the solar cell module100from the top of the working electrode10, and the portion viewed in the drawing is a working electrode contacting an upper surface of the vehicle body. Then, the counter electrode20may be located below the working electrode10. When the roof panel (sunroof) of the vehicle according to the exemplary embodiment of the present invention is constituted using the solar cell module100shown, it appears like the form in section (b) ofFIG. 6A.

The number of the solar cell modules100attached to the sunroof S according to the size of the sunroof S and the size of the solar cell module100attached to the sunroof S. One solar cell module100may be applied to an entire area of the sunroof S as in section (b) ofFIG. 6A, or a solar cell array (e.g., solar cell panel)110in which a plurality of solar cell modules100may be applied to an entire area of the sunroof S as in section (a) ofFIG. 6A.

When a plurality of solar cell modules100are connected as in section (a) ofFIG. 6A, the solar cell modules100arranged longitudinally may be connected in series and the solar cell modules100arranged transversely may be connected in parallel. However, the connection form may be changed based on specifications such as an output, a voltage, and a current of the solar cell module. Further, as shown in sections (c) and (d) ofFIG. 6B, a portion of the sunroof S of the vehicle other than an actual effective area (e.g., an area of a photonic electrode) of the solar cell module100may be masked to be attached to the manufactured solar cell module100. The masking of the portion other than the actual effective area of the solar cell module100may be directly coated on the sunroof S or may be coated at a periphery of the solar cell module100.

Although the exemplary embodiments of the present invention have been described in detail, the scope of the present invention is not limited thereto and various modifications and improvements of the present invention made by those skilled in the art also fall within the scope of the present invention.