HK1220038B - Photovoltaic glass with independent light traps - Google Patents

Description

Independent light trap type photovoltaic glass

Technical Field

The invention relates to photovoltaic glass applied to a solar photovoltaic cell, in particular to independent light trap type high-transmittance photovoltaic glass.

Background

At present, the shortage of energy has become a core problem which puzzles the development of countries in the world, solar energy is taken as a green energy which is abundant and can be sustainably utilized without causing environmental pollution, and the development and utilization of solar energy are important for the sustainable development of countries from the long-term strategic consideration. Currently, there are two main ways of utilizing solar energy worldwide: one is to convert solar radiation energy into heat energy by a heat collector, such as a solar water heater, etc.; the other is to convert solar energy into electric energy through a solar cell, i.e. photovoltaic power generation, such as a solar cell and the like. Regardless of whether the device converts light energy into heat energy or converts light energy into electric energy, the solar package assembly is one of the indispensable components, and the solar package assembly must have: high light transmittance (transmittance of not less than91% and Fe₂O₃Less than or equal to 150 ppm), water impermeability, no serious degradation of performance after long-term exposure to natural environment, high mechanical strength to external force and thermal stress, certain corrosion resistance, small expansion coefficient and the like. At present, only novel solar photovoltaic glass and a transparent plastic plate which can meet the above conditions are known, but as the transparent plastic plate is easy to age, has a low softening point and a large thermal expansion coefficient, the transparent plastic plate is not easy to be used as a cover plate, and the novel solar photovoltaic glass is widely used as a material of a solar packaging assembly due to the advantages of stable chemical properties, almost no aging and the like.

A solar cell is also called a "solar chip" or a "photovoltaic cell", and is a photoelectric semiconductor sheet that directly generates electricity by using sunlight. It can output voltage and generate current under the condition of loop as long as it is illuminated. Physically referred to as solar photovoltaic (abbreviated PV), abbreviated photovoltaic. The solar cell comprises photovoltaic glass, a solar cell and the like, wherein the photovoltaic glass is used for protecting a power generation main body (such as the solar cell), and the requirements of high light transmittance (as mentioned above, the light transmittance is generally more than 91%) and ultra-white toughening treatment are met; and the solar cell is mainly used for generating electricity. Among them, the conversion efficiency of the solar cell sheet 2 is a key index affecting the performance of the solar cell. Many factors affecting the conversion efficiency of solar cells are known at present, such as solar light intensity, cell materials, manufacturing process level, etc., and these factors make it difficult for the industry to improve the conversion efficiency by 1% in the research on the conversion efficiency of solar cells.

According to the structure of the solar cell, the transmittance of the photovoltaic glass directly affects the conversion efficiency of the solar cell, so if the transmittance of the photovoltaic glass can be improved, the photoelectric conversion efficiency of the solar cell can be improved.

In order to achieve low reflectance, low absorption and high light transmittance of light, patent document 1 discloses an optical element for controlling surface morphology to change specular reflection, which employs an optical device that can weaken the specular reflection of electromagnetic waves along the macroscopic surface of an object, reduce the total reflectance of the electromagnetic waves and function as an optical trap, the optical device having a conical relief with reflection and absorption capabilities, the surface of which is formed by a plurality of cones with different heights in a staggered arrangement; the height of the surface relief is between 0.1 micrometer and 2 millimeters, the basic repeating units of the surface relief are in the shape of a pyramid or a pyramid, and the base area of each repeating unit is between 0.04 micrometer and 8 millimeter square.

Non-patent document 2 discloses the use of optical traps in a crystalline silicon solar cell, which discloses the use of optical traps for reducing reflection, wherein a common optical trap includes a pyramidal pile face, the vertex angle of each cube of the pyramidal pile face is 70 ° 23', the pile face can reduce the reflectivity to 1/3 of a smooth face, and further calculation of the optical properties of the pile face shows that 11% of secondary reflection light can be reflected and refracted for the third time, so that the reflectivity of the pile face can be calculated to be 9.04%.

Patent document 3 discloses a glass sphere-small hole array light trap technology, which manufactures a small hole array on a thin plate made of a certain material, wherein two sides of the thin plate comprise various materials required by a thin film battery plated on the upper surface of the thin plate in sequence after a small hole side wall is plated with a metal reflection layer, a glass sphere is placed at the top of each small hole on the upper surface of the thin plate, the glass spheres which are closely dependent form a surface glass sphere array, the surface glass sphere array can gather sunlight into a small-scale strong light beam array, and the light beams can penetrate through the small holes of the thin plate and are trapped between the thin plate and an ultrathin photovoltaic cell panel positioned below the thin plate, and are absorbed and converted into light energy for many times to form a.

The above patent document 1 and non-patent document 2 adopt a taper/pyramid-shaped projection as a light trap structure, and the patent document 3 adopts a small aperture array light trap structure, but according to the descriptions of the above patent document and non-patent document, the reflectance after the secondary reflection can be reduced to 1% at the lowest. That is, the transmittance of light is not unexpectedly and significantly improved by the above-described technique.

Patent document 1: CN1157929A

Non-patent document 2: « application of light trap in crystalline silicon solar cell (« laser and optoelectronics development mobile phone, 2004, 41 vol., No. 5, pages 56-58, 44)

Patent document 3: CN 102623578A.

Disclosure of Invention

In view of the above problems in the prior art, an object of the present invention is to provide an independent light trap type photovoltaic glass applied to a solar cell, which employs a special independent light trap structure to reduce light reflectivity, thereby greatly improving light transmittance and further improving photoelectric conversion efficiency of a solar cell.

According to one technical scheme of the invention, the photovoltaic glass for the solar cell is provided, the surface of the photovoltaic glass is provided with an independent circular ring structure, namely an independent light trap structure, the outer diameter of a ring is within the range of 0.1-5 mm, and the included angle between an inner ring and an outer ring is less than or equal to 90 degrees, so that multiple reflection and refraction of light rays are completed in the independent circular ring structure.

Preferably, in the photovoltaic glass according to the present invention, smaller light traps are provided at blank positions of the individual light traps to improve light transmittance.

Preferably, in the photovoltaic glass according to the present invention, the smaller light trap is in the shape of a concave pointed cone.

Preferably, in the photovoltaic glass related to the invention, the independent light traps are closely arranged in a honeycomb shape.

Preferably, in the photovoltaic glass according to the present invention, the individual light traps are arranged in a square shape.

According to another aspect of the present invention, there is provided a method for manufacturing the photovoltaic glass of the present invention, comprising the steps of:

a special processing device is adopted to process a main wheel combined with an independent light trap structure;

the mother wheel is adopted to roll a roller, and the roller is arranged on a calender;

and pressing the photovoltaic glass by a calender.

The independent light trap type photovoltaic glass adopts a special annular light trap structure, so that 99.8% of incident light entering a glass interface for the first time can be captured, namely: 96% of the first generated reflected light is captured and used. The existing photovoltaic glass product can only capture about 30% -40% of reflected light entering a glass interface for the first time, so that more light can penetrate through the photovoltaic glass to participate in photoelectric conversion by adopting the photovoltaic glass, and the power generation rate of the solar cell is improved.

By the time of 2011, solar cells of about 3000 kilo-kilowatts have been produced by china, which accounts for about half of the total worldwide production, and correspondingly requires 3 billion square meters of photovoltaic glass. If the relevant solar cell module manufacturers purchase the photovoltaic glass (the photovoltaic glass only accounts for 8% of the total cost) at a purchase price 2% -3% higher than the current market price, the accounting proves that the relevant photovoltaic glass manufacturers can increase the profit by 2% -3%, and the relevant solar cell module manufacturers can increase the profit by 1.8% -2.7%, so that the commercial value and the market development prospect of the invention are very considerable.

Drawings

Fig. 1 is a structural view of a solar cell.

Fig. 2 is a schematic diagram of light transmission of the photovoltaic glass of the present invention.

Fig. 3 is a view showing an independent light trap structure of the photovoltaic glass of the present invention.

Fig. 4 is a view showing a planar arrangement of independent light trap structures of the photovoltaic glass of the present invention.

Fig. 5 is a view showing the surface structure of the photovoltaic glass of the present invention.

Fig. 6 is a perspective view of a small trap fabricated in a blank position of each optical trap.

Description of the reference numerals

1 photovoltaic glass

2 solar cell

3 substrate

4 adhesive

5 sealing glue

6 frame

10 independent optical traps

12 small traps.

Detailed Description

Certain terms are used throughout this specification to refer to particular components. As one skilled in the art will appreciate, identical components may generally be referred to by different names, and thus this document does not intend to distinguish between components that differ in name but not function. In this document, the terms "comprising", "including" and "having" are used in an open fashion and thus should be interpreted to mean "including but not limited to …". Further, the terms "about," "substantially," or "approximately" as may be used herein relate to industry accepted tolerances for the respective terms.

In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present apparatus, methods, and devices may be practiced without these specific details. Reference in the specification to "an embodiment," "an example," or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least that one embodiment or example, but not necessarily in other embodiments or examples.

The invention is further described below with reference to preferred embodiments and the accompanying drawings.

Fig. 1 is a structural view of a solar cell including a photovoltaic glass 1 for encapsulation protection of the solar cell, a solar cell sheet 2 as a semiconductor device for directly converting solar light energy into electric energy, a substrate 3, an adhesive 4, a sealant 5, a frame 6, and the like. As mentioned above, according to the structure of the solar cell shown in fig. 1, the photovoltaic glass 1 is one of the important components of the solar cell, and not only plays roles of protection, light transmission, and cell electrode, but also has important characteristics of increasing the light utilization rate and improving the cell efficiency, and the transmittance of the photovoltaic glass 1 directly affects the photoelectric conversion efficiency of the solar cell itself, so the present invention has been studied with a focus on improving the transmittance of the photovoltaic glass 1.

Currently, many effective methods have been proposed to improve the photoelectric conversion efficiency of the cell, such as quantum dot structures, wavelength conversion structures, and light trapping structures. The invention provides a novel light trapping structure (the light trapping structure is also called as 'light trap', and means that all or most of light rays cannot be reflected back after the light rays are irradiated into the structure), namely, the design of a ring-shaped mirror, so that multiple reflection and refraction of the light can be completed in an independent ring-shaped structure, and the independent ring-shaped structure is called as 'independent light trap' in the application. In addition, the scattering capacity of the light trapping structure on incident light is also an important index for judging the quality of the light trapping structure, the good light trapping structure not only can scatter a lot of light, but also the scattered light should be distributed in a larger angle range, so that more light can be increased in absorption optical path, the incident light with different angles can also enter the absorption range of the solar cell, the oblique sunlight can be fully utilized in the actual use process of the cell, and the power generation capacity can be improved. The existing photovoltaic glass is pressed with hillock-shaped bulges which are distributed irregularly on the surface, but the structure can capture only a small amount of reflected light. In order to fully capture reflected light and improve light transmittance, the invention adopts a plurality of independent light trap units and makes the independent light trap units distributed on the surface of the photovoltaic glass 1, so that the reflected light can be almost totally incorporated into the solar cell piece 2 after the light is reflected and refracted for a plurality of times, thereby greatly improving the light transmittance, improving the photoelectric conversion efficiency of the solar cell and obtaining the outstanding practical application effect.

Fig. 5 is a view showing a surface structure of the photovoltaic glass of the present invention, and as shown in fig. 5, the bottom surface of the photovoltaic glass 1 maintains a conventional mesh surface, and the top surface (i.e., the upper surface) thereof has a pattern pressed by a dedicated embossing apparatus, the pattern is an independent circular ring structure, i.e., independent light traps 10, each of the independent light traps 10 is closely arranged in a honeycomb shape, and the independent light traps 10 are uniformly and continuously distributed on the top surface.

FIG. 3 shows a planar structure of the independent optical trap, wherein the included angle of the inner and outer rings of the ring-shaped structure is <90 °, the outer diameter of the ring is determined by the thickness of the photovoltaic glass, and in the present invention, the outer diameter of the ring is determined to be 0.1-5 mm.

Fig. 4 shows a planar arrangement of individual light traps of the photovoltaic glass of the present invention. As shown in fig. 4, the individual light traps 10 are closely arranged in a honeycomb shape, thereby making the most use of the surface area. Meanwhile, in order to improve the light transmittance, small traps 12 may be formed at the junction of the ring of each individual light trap 10.

Fig. 6 is a perspective view of a small trap fabricated in the blank position of each individual optical trap. As shown in fig. 6, the small traps 12 have a concave pointed conical shape, thereby improving light transmittance.

In the present embodiment, the individual light traps 10 are arranged in a honeycomb shape, but the arrangement of the individual light traps 10 is not limited to the honeycomb type compact arrangement, and for example, a square arrangement may be adopted, but the arrangement form such as the square arrangement is not preferred in the present invention because the processing is simple but the efficiency is slightly poor.

In the invention, the special annular light trap structure is adopted to manufacture photovoltaic glass and other transparent materials of solar cells. Because the photovoltaic glass has the special independent light trap structure, most (about 99.8%) of light rays entering the glass can generate secondary reflection, tertiary reflection, quartic reflection or even more reflections, so that the light rays reflected back to the atmosphere are greatly reduced, and the transmittance of the light rays is enhanced.

The light transmission principle of the photovoltaic glass of the present invention is explained in detail below. According to physical principles, when light enters from one medium to another, reflection and refraction will occur as long as the density of the media is different. After incident light generates primary reflection and primary refraction on the inclined plane of the light trapping structure of the photovoltaic glass, a part of reflected light is incident to the adjacent inclined plane again to generate secondary incidence again, so that the incident light is increased. Meanwhile, in the process of multiple times of incidence, the incident light with different angles is generated, and the effect of light scattering is achieved.

Fig. 2 is a schematic diagram of light transmission of the photovoltaic glass of the present invention, as shown in fig. 2, when a light ray S is incident on the a-B inclined surface of the independent light trap 10 of the present invention, it is reflected and refracted to generate a reflected light ray S1 and a refracted light ray S2, and when a reflected light ray S1 advances to the adjacent inclined surface of the independent light trap 10, i.e., the B-C inclined surface, the reflected light ray S1 is reflected and refracted again to generate a reflected light ray S3 and a refracted light ray S4 (not shown), the reflected light ray S3 is reflected and refracted again at another interface to generate a reflected light ray S5 and a refracted light ray S6.

In the present invention, as shown in fig. 2, when the first reflection and refraction occurs, about 96% of incident light rays are refracted on the inclined plane of the independent optical trap structure, and about 4% of the incident light rays are reflected on the inclined plane, about 4% of the reflected light rays continue to be reflected and refracted on the adjacent inclined plane of the independent optical trap structure, and after multiple reflections and refractions, finally, about 3.64% (i.e., 4% × 96% ═ 3.64%) of about 4% of the reflected light rays are captured, and only about 0.16% of the light rays are returned to the atmosphere.

In addition, in order to process the flower shape of the independent light trap structure, the inventor of the present application develops a corresponding special device and a special tool, so that a female wheel can be easily manufactured, and the conventional technology is to use the female wheel to roll a roller. Therefore, the inventor conducts a plurality of tests to roll and roll a tapered pattern with the diameter of 0.15mm on a roller with the diameter of 300mm, and then only needs to replace the roller on the existing photovoltaic production line with the roller of the invention, so that the novel independent light trap type photovoltaic glass can be produced.

The following is a brief description of the process of manufacturing the photovoltaic glass of the independent light trap structure of the present invention.

The inventor of the application adopts the special equipment and the special cutter to process a mother wheel with an independent light trap structure, then adopts the mother wheel to roll a roller, and finally installs the roller on a calender to press transparent plates such as glass, PMMA, PET and the like.

From the technical aspect, the existing roller is processed by adopting an etching method, the processing process is complex, and the cost is high. The rolling method adopted by the invention can reduce the cost and is simple and reliable.

From the above description of the embodiments, those skilled in the art will appreciate that various modifications and substitutions can be made to the specific embodiments of the present invention without departing from the spirit and scope of the invention. Such modifications and substitutions are intended to be included within the scope of the present invention as defined by the appended claims.

Claims (9)

1. The photovoltaic glass for the solar cell is characterized in that an independent circular ring-shaped structure, namely an independent light trap structure, is arranged on the surface of the photovoltaic glass, wherein the independent circular ring-shaped structure comprises an outer wall and a sharp conical bulge embedded inside the outer wall, the outer wall forms an outer ring of the independent circular ring-shaped structure, the diameter of a circle formed by the top of the outer ring is within the range of 0.1-5 mm, the outer surface of the sharp conical bulge forms an inner ring, and an included angle formed by intersection of the outer wall and the outer surface of the sharp conical bulge is smaller than or equal to 90 degrees, so that all light rays incident into the independent circular ring-shaped structure are reflected and refracted for multiple times in the circular ring-shaped structure formed by the outer wall and the outer surface of the sharp conical bulge, and 99.8% of incident light entering the surface of the photovoltaic glass for the first time is captured.

2. The photovoltaic glass of claim 1, wherein smaller light traps are provided in vacant locations of the individual light traps to improve light transmission.

3. The photovoltaic glass of claim 2, wherein the smaller light traps are concave, pointed conical shapes.

4. The photovoltaic glass of any one of claims 1-3, wherein the individual light traps are closely arranged in a honeycomb shape.

5. The photovoltaic glass of any of claims 1-3, wherein the individual light traps are arranged in a square.

6. A solar cell having the photovoltaic glass of any one of claims 1 to 5 for encapsulation protection.

7. A device for processing the flower shape of the surface of the photovoltaic glass of any one of claims 1 to 5, wherein the flower shape is an independent circular ring-shaped structure, namely an independent annular light trap structure, wherein the independent circular ring-shaped structure comprises an outer wall and a sharp conical bulge nested inside, the outer wall forms an outer ring of the independent circular ring-shaped structure, the diameter of a circle formed at the top of the outer ring is within the range of 0.1-5 mm, the outer surface of the sharp conical bulge forms an inner ring, and an included angle formed by intersection of the outer wall and the outer surface of the sharp conical bulge is smaller than or equal to 90 degrees.

8. A method for manufacturing the photovoltaic glass of claims 1 to 5, comprising the steps of:

processing a combined mother wheel of an independent light trap structure by using the processing device of claim 7;

the mother wheel is adopted to roll a roller, and the roller is arranged on a calender;

and pressing the photovoltaic glass by the calender.

9. Method according to claim 8, wherein said method can be used for the manufacture of sheets of transparent material of glass, PMMA, PET.