TWI482288B - Solar cell, method of manufacturing the same and module comprising the same - Google Patents

Description

Solar cell, manufacturing method thereof and module thereof

The invention relates to a battery, a manufacturing method and a module, in particular to a solar battery, a manufacturing method thereof and a module thereof.

Referring to Fig. 1, a known twinned solar cell mainly comprises: a battery body 91 for converting light energy into electrical energy, and a front electrode 92 and a back electrode (not shown) for conducting current. The front electrode 92 includes at least one bus bar electrode 921, and a plurality of finger bar electrodes 922 that are laterally connected to the bus electrode 921 and have an elongated shape. At present, the front electrode 92 is usually formed by screen printing or electroplating, and the shape design of the front electrode 92 is limited by the process technology and the shading effect, and the line width of the finger electrodes 922 must be The line spacing or line height is varied to achieve better current collection efficiency and photoelectric conversion efficiency.

In the conventional battery, the area ratio of the finger electrode 922 occupying the area of the battery other than the bus electrode 921 is still more than 6%. If it is desired to reduce the line width of the finger electrode 922 or increase the line pitch, To reduce the shading ratio, the screen design must be changed, but the hole spacing of the screen emulsion layer has its limits, resulting in a limited line width or line spacing design. Moreover, no electrodes are disposed between the adjacent finger electrodes 922, and the electrodes are not closely arranged, resulting in a large area of the battery having no electrodes, thereby reducing the photocurrent collection efficiency, so the known battery is The electrode structure needs to be improved.

Accordingly, it is an object of the present invention to provide a solar cell capable of increasing the amount of light incident, photocurrent, and photoelectric conversion efficiency, a method of manufacturing the same, and a module thereof.

Therefore, the solar cell of the present invention comprises: a battery body having a light receiving surface, a bus electrode on the light receiving surface, a plurality of island electrodes spaced apart from each other on the light receiving surface, and a transparent conductive Floor. The transparent conductive layer is located on the battery body and covers the first electrodes and is connected to the bus electrodes. The transparent conductive layer has an opening corresponding to the position of the bus electrodes for the bus electrodes to be exposed.

The solar cell module of the present invention comprises: a first plate and a second plate disposed oppositely, a plurality of solar cells as described above and arranged between the first plate and the second plate, and a package. The encapsulant is located between the first plate and the second plate and is wrapped around the solar cells.

The method for manufacturing a solar cell of the present invention comprises: providing a battery body having a light receiving surface; forming a bus electrode on the light receiving surface of the battery body and a plurality of first electrodes spaced apart from each other and forming an island shape; and forming a An open transparent conductive layer covers the first electrode and connects the bus electrode, and positions the opening corresponding to the position of the bus electrode to expose the bus electrode.

The effect of the invention is that the first electrode is island-shaped and spaced apart, instead of the traditional long-shaped finger electrode, the electrode area can be effectively reduced In order to reduce the light-shielding ratio of the light-receiving surface of the battery, the amount of light entering, the photocurrent, and the conversion efficiency are improved. Moreover, the shape of the first electrodes is designed to facilitate distribution of each region on the light-receiving surface, thereby forming a perfect conductive network, which also contributes to improving current collection efficiency.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments.

Referring to Figures 2, 3 and 4, a preferred embodiment of the solar cell module of the present invention comprises: a first plate 1 and a second plate 2 disposed opposite each other, and a plurality of arrays arranged on the first plate 1 The solar cell 3 between the second plate 2 and at least one of the first plate 1 and the second plate 2 are wrapped around the solar cells 3.

The first plate 1 and the second plate 2 are not particularly limited in implementation, and a glass or plastic plate may be used, and the plate on one side of the light receiving surface of the battery must be permeable to light. The material of the encapsulant 4 is, for example, a translucent ethylene vinyl acetate copolymer (EVA). Of course, other materials suitable for packaging may be used.

The solar cells 3 are electrically connected through soldering wires (not shown). The configurations of the solar cells 3 are the same, and only one of them will be described below as an example.

The solar cell 3 includes a battery body 31, at least one bus electrode 32, a plurality of first electrodes 33, and a transparent conductive layer 34.

The battery body 31 includes an opposite light receiving surface 312 and a back The substrate 311 of the surface 313, an inner emitter layer 314 formed on the light-receiving surface 312 of the substrate 311, and an anti-reflection layer 315 on the light-receiving surface 312 are also disposed on the surface 312. .

The substrate 311 is, for example, a germanium substrate, and one of the substrate 311 and the emitter layer 314 is an n-type semiconductor, and the other is a p-type semiconductor, thereby forming a pn junction. The material of the antireflective layer 315, for example, silicon nitride (SiN _x), can be used to reduce reflected light to increase the amount of incident light.

The battery of this embodiment includes two bus electrodes 32 on the light receiving surface 312, and the bus electrodes 32 pass through the anti-reflection layer 315 to contact the light receiving surface 312. The bus electrodes 32 all extend along a first direction 51 and are spaced apart along a second direction 52 that is perpendicular to the first direction 51. In practice, the number of the bus electrodes 32 is not limited to two, and may be one or three. The bus electrodes 32 do not have to be continuous strips as in this embodiment. For example, each of the bus electrodes 32 may also include a plurality of electrode portions spaced along the first direction 51. Each electrode portion may be rectangular. , round or other pattern.

The first electrodes 33 of the present embodiment pass through the anti-reflection layer 315 to contact the light-receiving surface 312, and the first electrodes 33 are spaced apart from each other on the light-receiving surface 312. In fact, the battery of this embodiment includes a plurality of rows of first electrode units 330 arranged along the second direction 52. Each row of first electrode units 330 includes several of the first electrodes 33, each row The first electrodes 33 of the first electrode unit 330 are spaced apart along the first direction 51, and the positions of the first electrodes 33 of the adjacent two rows of the first electrode units 330 are staggered. That is, each of the first two electrodes of the adjacent two rows of first electrode units 330 On different lines along the second direction 52.

The shape of the first electrodes 33 may be island-shaped, and the island shape may include a circle, a semicircle, an ellipse or the like. When the shape of the first electrode 33 is circular, the radius of each of the first electrodes 33 may be 60 μm to 70 μm. The area of the region of the light-receiving surface 312 that does not include the bus electrode 32 is defined as A, and the total area of the first electrodes 33 is B, preferably B/A < 0.04.

Specifically, the area A of the present embodiment is 23895 mm ² . Each of the three first electrodes 33 of the present embodiment is arranged in an equilateral triangle, and the distance d1 of the center point of any two of the first electrodes 33 of each set of equilateral triangles is 550 μm, and each first electrode The radius of 33 is 70 μm, the total area of all the first electrodes 33 is B = 331.59 mm ² , and B/A = 331.59 / 23895 = 0.0139.

The design of B/A<0.04 of the present invention can effectively reduce the area of the first electrode 33, thereby reducing the light-shielding ratio of the light-receiving surface 312 of the battery, thereby improving the amount of light entering, the photocurrent and the conversion efficiency, and reducing the screen printing electrode. The amount of slurry used reduces production costs. Moreover, since the first electrodes 33 are island-shaped and spaced apart, although the total area of the first electrode 33 of the present invention is smaller than the total area of the conventional finger electrodes, the collection efficiency of the photocurrent is not affected because such The first electrode 33 can be evenly distributed on each of the regions on the light receiving surface 312 to form a perfect conductive network to avoid the presence of a large and continuous electrodeless region on the battery. Therefore, the shape and arrangement of the first electrode 33 of the present invention contribute to improving current collection efficiency and increasing photocurrent.

The transparent conductive layer 34 of the embodiment is located on the anti-reflection layer 315 of the battery body 31, and covers the first electrodes 33 and connects the bus electrodes. 32. The first electrodes 33 are electrically connected to the bus electrodes 32 by the transparent conductive layer 34. Moreover, the transparent conductive layer 34 is covered almost entirely, which helps to collect the photocurrent, and at the same time, because of the high transmittance of the transparent conductive layer 34, the light absorption effect of the battery is small.

The material of the transparent conductive layer 34 is, for example, a metal oxide such as indium tin oxide (ITO), aluminum zinc oxide (AZO), gallium zinc oxide (GZO), or the like. The transparent conductive layer 34 has two openings 341 spaced apart along the second direction 52. The openings 341 extend along the first direction 51 and respectively correspond to the positions of the bus electrodes 32 for the bus electrodes. 32 exposed.

In this embodiment, the length d2 of each opening 341 along the second direction 52 is slightly smaller than the length d3 of each of the bus electrodes 32 along the second direction 52, so the transparent conductive layer 34 is actually each bus electrode. An upper surface 321 of 32 is partially covered, but is not limited thereto. For example, the transparent conductive layer 34 may not cover the upper surfaces 321 and contact the side surfaces 322 of the bus electrodes 32 as long as the transparent conductive layer 34 can contact the bus electrodes 32. The upper surface 321 of the bus electrode 32 needs to be exposed because it is necessary to solder the soldering wire to the bus electrode 32 during the assembly of the battery module to connect the adjacent cells in series.

It is to be noted that the number of the openings 341 on each of the bus electrodes 32 is not limited to one. For example, each of the bus electrodes 32 may also be provided with a plurality of openings 341 spaced along the first direction 51. In addition, since the battery of the present invention may also include only one bus electrode 32, the transparent conductive layer 34 may be provided with only one opening 341 corresponding to the bus electrode 32.

The solar cell 3 actually includes a second electrode (not shown) on the back surface 313 of the battery body 31 for cooperating with the bus electrode 32 and the first electrode 33 to output electrical energy, but due to the second electrode It is not the improvement focus of the present invention, so it will not be described.

Referring to Figures 5 and 6, a preferred embodiment of the method for fabricating a solar cell of the present invention comprises:

(1) Step 61: The battery body 31 is provided, and the emitter layer 314 is formed on the light-receiving surface 312 of the substrate 311 by a diffusion process, and the emitter layer 314 is formed on the emitter layer 314 by vacuum plating or the like. Anti-reflection layer 315. The vacuum coating method of the present invention comprises physical vapor deposition (PVD), chemical vapor deposition (CVD), etc., and the chemical vapor deposition comprises PECVD.

(2) Step 62: The first electrodes 33 are formed on the light receiving surface 312 of the battery body 31 so as to be spaced apart from each other and formed in an island shape. When the step is performed, the conductive paste of the bus electrode 32 and the first electrode 33 is coated on the anti-reflective layer 315 by screen printing, followed by high-temperature sintering, which erodes and The emitter layer 314 is contacted through the anti-reflective layer 315, that is, the light-receiving surface 312 is contacted, and the bus bar electrode 32 and the first electrode 33 are formed when the conductive paste is solidified. It should be noted that the bus electrode 32 and the first electrode 33 of the present embodiment are formed on the anti-reflection layer 315, that is, indirectly on the light-receiving surface 312. However, since the anti-reflection layer 315 is not required in the present invention, the bus electrodes 32 and the first electrodes 33 may be formed directly on the light-receiving surface 312. The formation of the bus electrodes 32 and the first electrodes 33 on the light receiving surface 312 according to the present invention may include direct formation and indirect formation.

It should be noted that the bus electrodes 32 and the first electrodes 33 can be formed at the same time in a single screen printing process as described in the embodiment, and the materials of the two are the same. However, the bus electrode 32 and the first electrode 33 may also be sequentially formed. For example, the bus electrodes 32 may be screen printed first and then slightly dried, and then the first electrodes 33 are screen printed, and finally sintered together to form a solidification; The screen printing order of the two can also be interchanged, and the order of production is not limited. When the bus electrode 32 and the first electrode 33 are formed in stages, different slurry materials may be used. In this case, the bus electrodes 32 may be selected for the slurry which does not pass through the anti-reflection layer 315 after high-temperature sintering. Material. In addition, since the present invention actually includes a second electrode on the back surface 313 of the battery body 31, the second electrode can be formed by screen printing.

(3) Step 63: forming the transparent conductive layer 34 such that the transparent conductive layer 34 covers the first electrodes 33 and connects the bus electrodes 32, and positions the opening 341 corresponding to the position of the bus electrode 32 so that the The bus electrode 32 is exposed. Specifically, in this embodiment, the transparent conductive layer 34 is formed by vacuum coating, and the bus electrode 32 is shielded by a mask 7 when the film is coated. The pattern of the mask 7 corresponds to the pattern of the transparent conductive layer 34. The transparent conductive layer material can be deposited on the unobstructed portion of the battery, and the transparent conductive layer 34 formed by the plating film has the openings 341.

It should be noted that the electrode improved structure of the present invention can be applied to a double-sided photocell as well as a double-sided photocell. The double-sided light-input cell has opposite light-receiving surfaces, and one of the light-receiving surfaces or the electrode structures on the two light-receiving surfaces can be designed as the above-mentioned The form of the embodiment is the form of the aforementioned bus electrode 32 and the island-shaped first electrode 33.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

1‧‧‧ first plate

2‧‧‧Second plate

3‧‧‧Solar battery

31‧‧‧ battery body

311‧‧‧Substrate

312‧‧‧Stained surface

313‧‧‧Back

314‧‧ ‧ emitter layer

315‧‧‧Anti-reflective layer

32‧‧‧Concurrent electrode

321‧‧‧ upper surface

322‧‧‧ side

33‧‧‧First electrode

330‧‧‧First electrode unit

34‧‧‧Transparent conductive layer

341‧‧‧ openings

4‧‧‧Package

51‧‧‧First direction

52‧‧‧second direction

61~63‧‧‧Steps

7‧‧‧ mask

D1‧‧‧ distance

D2, d3‧‧‧ length

1 is a schematic top plan view of a known solar cell; FIG. 2 is a partial side cross-sectional view showing a preferred embodiment of the solar cell module of the present invention; and FIG. 3 is a plan view of a solar cell of the preferred embodiment. Figure 4 is a cross-sectional view taken along line AA of Figure 3; Figure 5 is a block flow diagram of a preferred embodiment of a method for fabricating a solar cell of the present invention; and Figure 6 is a step of the method Schematic diagram of the process.

3‧‧‧Solar battery

31‧‧‧ battery body

32‧‧‧Concurrent electrode

321‧‧‧ upper surface

33‧‧‧First electrode

330‧‧‧First electrode unit

34‧‧‧Transparent conductive layer

341‧‧‧ openings

51‧‧‧First direction

52‧‧‧second direction

D1‧‧‧ distance

D2, d3‧‧‧ length

Claims (11)

A solar cell comprising: a battery body having a light receiving surface; a bus electrode located on the light receiving surface; a plurality of island-shaped first electrodes spaced apart from each other on the light receiving surface; and a transparent conductive layer located at The battery body covers the first electrode and is connected to the bus electrode. The transparent conductive layer has an opening corresponding to the position of the bus electrode for exposing the bus electrode. The solar cell of claim 1, wherein the bus electrode extends in a first direction, the solar cell comprises a plurality of rows of first electrode units, and each row of first electrode units comprises the first electrodes And a plurality of the first electrodes in each row of the first electrode units are spaced apart along the first direction, and the positions of the first electrodes of the adjacent two rows of the first electrode units are staggered. The solar cell according to claim 1, wherein the area of the light-receiving surface excluding the bus electrode is A, the total area of the first electrodes is B, and B/A < 0.04. The solar cell according to claim 3, wherein each of the first electrodes has a circular shape and a radius of 60 μm to 70 μm. The solar cell of claim 1, wherein the battery body comprises a substrate having the light-receiving surface, and an anti-reflection layer on the light-receiving surface, the transparent conductive layer is located on the anti-reflection layer. The first electrodes pass through the anti-reflection layer to contact the light receiving surface. The solar cell according to claim 1, wherein the transparent conductive layer has only one opening for exposing the bus electrode. A solar cell module comprising: a first plate and a second plate disposed oppositely; and a plurality of solar cells according to any one of claims 1 to 6 arranged on the first plate and the Between the second plates; and a packaging material between the first plate and the second plate, and wrapped around the solar cells. A method for manufacturing a solar cell, comprising: providing a battery body having a light receiving surface; forming a bus electrode on the light receiving surface of the battery body and a plurality of first electrodes spaced apart from each other and forming an island shape; and forming a The transparent conductive layer is opened such that the transparent conductive layer covers the first electrodes and is connected to the bus electrode, and the position of the opening corresponds to the position of the bus electrode to expose the bus electrode. The method for manufacturing a solar cell according to claim 8, wherein the transparent conductive layer is formed by vacuum coating, and the bus electrode is shielded by a mask during coating to have the transparent conductive layer formed. The opening. The method for manufacturing a solar cell according to the above-mentioned item 8, wherein the bus electrode and the first electrode are formed by screen printing. The method of manufacturing a solar cell according to claim 8 or 9, wherein the battery body comprises a substrate having the light receiving surface, An emitter layer formed on the light receiving surface, and an antireflection layer on the emitter layer; when the bus electrode and the first electrode are formed, the screen is printed on the antireflection layer by screen printing Conductive slurry and passing the conductive paste through the anti-reflective layer to contact the emitter layer.