TWM485508U - Solar cell with backside wide and narrow electrode blocks - Google Patents

Abstract

A solar cell with backside wide and narrow electrode blocks: includes a substrate having a backside and a front side, which is a light receiving surface for receiving light; and multiple backside electrodes disposed on the backside. Each backside electrode includes M wide electrode blocks each extending along a lengthwise direction; and N narrower electrode blocks, each of which extends in the lengthwise direction and is disposed between and electrically connected to the neighboring wide electrode blocks. A maximum width of the wide electrode block is greater than a maximum width of the narrower electrode block, where M is a positive integer greater than 1, and N is a positive integer greater than 0.

Description

Solar cell with back thickness electrode block

The present invention relates to a solar cell having a back thickness electrode block.

A solar cell is an energy-converting photovoltaic element that converts light energy into electrical energy after being irradiated by sunlight. This photoelectric element is called a solar cell. From a physics point of view, some people call it Photovoltaic (PV) batteries.

Conventional solar cells are manufactured by first providing a substrate and then performing chemical vapor deposition (such as PECVD) on the germanium substrate to form an anti-reflective layer, followed by screen printing and co-firing. An electrode is formed on the anti-reflection layer and the electrode penetrates the anti-reflection layer to be electrically connected to the germanium substrate.

A conventional solar cell usually comprises two or three back electrodes, and the material of the back electrode, such as silver, is printed on a back metal layer (such as aluminum) and then sintered. The back metal layer can increase the back side field to increase the efficiency of the solar cell. However, the back electrode reduces the area of the back metal layer, thereby reducing the efficiency of the solar cell. Therefore, the back electrode affects the consumption of silver and reduces the back surface electric field.

Table 1 shows the back side data for four conventional solar cells. As shown in Table 1, the four solar cells have three back electrodes on the back side, and each back electrode has a rectangular shape. The shape, the back silver area represents the area of the back electrode, and the back aluminum area ratio ranges from about 94.15% to 95.07%.

Accordingly, it is an object of the present invention to provide a solar cell having a back-thickness electrode block, thereby having an improved efficiency.

To achieve the above object, the present invention provides a solar cell having a back thickness electrode block comprising: a substrate having a front surface and a back surface, a front surface being a light receiving surface for receiving light; and a plurality of back electrodes disposed on the back surface on. The back electrode comprises: M coarse electrode blocks, the thick electrode block extends along a length direction; and N fine electrode blocks, the fine electrode blocks extend along the length direction, and are located adjacent to the coarse electrode blocks Between and adjacent to the adjacent coarse electrode blocks, the maximum width of the thick electrode block is greater than the maximum width of the fine electrode block, where M is a positive integer greater than 1, and N is a positive integer greater than zero.

Therefore, the solar cell of the above-mentioned embodiment of the present invention can improve the current series output characteristics between the cells in the module, in addition to improving the back surface electric field, thereby improving the efficiency of the solar cell and contributing to the actual welding. .

In order to make the above description of the present invention more comprehensible, the preferred embodiments are described below, and are described in detail below with reference to the accompanying drawings.

W21‧‧‧Max width

W26‧‧‧Max width

X‧‧‧Width direction

Y‧‧‧ Length direction

1‧‧‧Solar battery

10‧‧‧Substrate

10A‧‧‧ positive

10B‧‧‧Back

20‧‧‧Back electrode

21‧‧‧Deep electrode block

26‧‧‧ fine electrode block

30‧‧‧ Bus bar electrode

40‧‧‧Finger electrode

1 shows a schematic view of the front side of a solar cell according to a first embodiment of the present invention.

2 is a schematic view showing the back surface of a solar cell according to a first embodiment of the present invention.

Figure 3 shows a schematic diagram of a comparative example of Figure 2.

4 and 5 show partial schematic views of two comparative examples of Fig. 2.

Fig. 6 is a partial schematic view showing the back surface of a solar cell according to a second embodiment of the present invention.

Fig. 7 is a partial schematic view showing the back surface of a solar cell according to a third embodiment of the present invention.

Fig. 8 is a partial schematic view showing the back surface of a solar cell according to a fourth embodiment of the present invention.

Figure 9 shows the shape of various coarse electrode blocks that can be applied to the present embodiment.

The embodiment of the present invention changes the continuous electrode on the back surface into a discontinuous electrode to reduce the coverage area of the silver material of the back electrode and increase the back surface electric field of the aluminum, thereby improving the efficiency of the solar cell. In order to prevent the module manufacturers of solar cells from being affected by poor soldering quality when welding ribbons, the discontinuous electrodes are often connected in series by thin wires to achieve high efficiency and excellent quality.

Fig. 1 shows a schematic view of the front side of a solar cell 1 according to a first embodiment of the present invention. Fig. 2 shows a schematic view of the back side of the solar cell 1 according to the first embodiment of the present invention. As shown in FIGS. 1 and 2, the solar cell 1 of the present embodiment includes a substrate 10, a plurality of back electrodes 20, a plurality of bus electrodes 30, and a plurality of finger electrodes 40. The substrate 10 has a front surface 10A and a back surface 10B. The front surface 10A is a light collecting surface for receiving light and preventing The light is reflected out. The bus bar electrode 30 and the plurality of finger electrodes 40 are located on the front surface 10A. The back electrode 20 is located on the back surface 10B. In the present embodiment, the three back electrodes 20 and the three bus electrodes 30 are described, but the present invention is not limited thereto.

The back electrode 20 includes M coarse electrode blocks 21 and N fine electrode blocks 26. The thick electrode block 21 extends along a length direction Y, the so-called length direction refers to the longitudinal direction, and the direction X in the drawing is defined as the width direction X. The fine electrode block 26 extends along the length direction Y, is located between the adjacent coarse electrode blocks 21, and is electrically connected to the adjacent coarse electrode blocks 21. The maximum width W21 of the thick electrode block 21 is greater than the maximum width W26 of the fine electrode block 26, where M is a positive integer greater than 1, and N is a positive integer greater than zero. In the present embodiment, M is equal to 5 and N is equal to 4, but the present invention is not strictly limited thereto. Further, in the back surface electrode 20, the coarse electrode blocks 21 have different lengths, which are presented in two lengths in this embodiment. Furthermore, the length of the coarse electrode block 21 located in the middle is shorter than the length of the other thick electrode blocks 21, and the arrangement of the thick electrode blocks 21 is vertically symmetrical, and these fine electrode blocks 26 have the same length, adjacent The coarse electrode blocks 21 of the back electrodes 20 of these are arranged in alignment with each other.

In the present embodiment, the thick electrode block 21 has a shape of a rectangle and two semicircles.

Figure 3 shows a schematic diagram of a comparative example of Figure 2. 4 and 5 show partial schematic views of two comparative examples of Fig. 2. As shown in FIG. 3, the difference from FIG. 2 is that there is no fine electrode block 26. As shown in FIG. 4, the difference from FIG. 3 is that the thick electrode block 21 has a rectangular shape. As shown in FIG. 5, the difference from FIG. 3 is that the thick electrode block 21 has an elliptical shape. The reference datum for these differently shaped patterns is the maximum range of rectangles that can be filled or inscribed in one of the same dimensions.

The new type of person in this case specially tested the back electrodes of these patterns. The results are shown in Table 2 and Table 3. In Table 2, 200 solar cells of each of the four patterns were fabricated, and the average efficiency, open circuit voltage (Voc), short circuit current Isc, fill factor FF (Fill factor), series resistance Rs, and the fill factor FF were measured. The ratio of the power rectangular area to the product of the short circuit current and the open circuit voltage.

Referring to Figure 2 with the fine electrode block 26, it can be seen from Table 2 and Table 3 that the area of the elliptical silver pad (Ag pad) of Figure 5 is the smallest, indicating that the back surface of the back aluminum has the highest electric field, so the FF is the highest. Voc also has gain, and the final battery efficiency is also the highest. The FF of the silver pad of the pattern of Figure 3 is second, while the FF of the rectangular silver pad of Figure 4 is the lowest. However, if the area of the silver pad is too small, the tension between the ribbon and the silver pad will be too low when the module is soldered. Therefore, the area of the silver pad should be maintained to a certain size to ensure that the welding force is in conformity with the specifications. Comparing Table 3 with Table 1, it can be found that the area ratio of the back aluminum is greater than 95.07%, and the highest is 97.37%. Thus, embodiments of the present invention are more efficient than prior art techniques.

2 and FIG. 3 are compared, with the difference that the pattern of FIG. 2 has the lowest FF because of the fine electrode block 26. However, if the silver pads (the thick electrode blocks 21) are connected by a thin silver wire (fine electrode block 26), the Voc of the two is relatively high, and the Isc is relatively high when the fine silver wires are connected, for the cells in the module. The current series output is preferred. Therefore, it can be proved that there are fine electrodes The presence of block 26 also helps to improve overall efficiency.

Fig. 6 is a partial schematic view showing the back surface of a solar cell according to a second embodiment of the present invention. With the above description, the pattern of FIG. 4 can also be applied to the fine electrode block 26 to obtain the pattern of FIG.

Fig. 7 is a partial schematic view showing the back surface of a solar cell according to a third embodiment of the present invention. By the above description, the pattern of FIG. 5 can also be applied to the fine electrode block 26 to obtain the pattern of FIG.

Fig. 8 is a partial schematic view showing the back surface of a solar cell according to a fourth embodiment of the present invention. As shown in FIG. 8, the present embodiment is similar to the first embodiment except that the coarse electrode blocks 21 of the adjacent back electrodes 20 are arranged in a staggered manner. Thus, when welding the ribbon, it helps to distribute the stress between the ribbon and the silver pad.

Figure 9 shows the shape of various coarse electrode blocks that can be applied to the present embodiment. It is worth noting that although the shape of the thick electrode block is derived from a rectangular shape, its shape is not limited after it becomes discontinuous. Therefore, various shapes as shown in Fig. 9 can be used, even in combination or in a variable use, as long as the total area of the back aluminum is larger than the area of the original rectangular shape.

The solar cell of the above-mentioned embodiment of the present invention can improve the current series output characteristics between the cells in the module in addition to the back surface electric field, thereby improving the efficiency of the solar cell and contributing to actual soldering.

The specific embodiments set forth in the detailed description of the preferred embodiments are merely used to facilitate the description of the technical scope of the present invention, and are not intended to limit the present invention narrowly to the above embodiments, without departing from the spirit of the present invention and the following claims. The scope of the scope and the implementation of various changes are within the scope of this new model.

W21‧‧‧Max width

W26‧‧‧Max width

X‧‧‧Width direction

Y‧‧‧ Length direction

1‧‧‧Solar battery

10‧‧‧Substrate

10B‧‧‧Back

20‧‧‧Back electrode

21‧‧‧Deep electrode block

26‧‧‧ fine electrode block

Claims (10)

A solar cell having a back thickness electrode block, comprising: a substrate having a front surface and a back surface, the front surface being a light receiving surface for receiving light; and a plurality of back electrodes disposed on the back surface, the back surface electrode The method includes: M coarse electrode blocks extending along a length direction; and N fine electrode blocks extending along the length direction and adjacent to the coarse electrode regions Between the blocks, and electrically connecting the adjacent coarse electrode blocks, the maximum width of the thick electrode block is greater than the maximum width of the fine electrode block, wherein M is a positive integer greater than 1, and N is a positive greater than 0 Integer. The solar cell of claim 1, wherein M is equal to 5 and N is equal to 4. The solar cell of claim 1, wherein in the back electrode, the length of the coarse electrode block located in the middle is shorter than the length of the other thick electrode block. The solar cell of claim 1, wherein in the back electrode, the fine electrode blocks have the same length. The solar cell of claim 1, wherein the coarse electrode blocks have different lengths in the back electrode. The solar cell of claim 1, wherein the coarse electrode blocks of the adjacent back electrodes are aligned with each other. The solar cell of claim 1, wherein the coarse electrode blocks of the adjacent back electrodes are staggered. The solar cell of claim 1, wherein the thick electrode block has a rectangular shape. The solar cell of claim 1, wherein the thick electrode block has an elliptical shape. The solar cell of claim 1, wherein the thick electrode block has a shape of a rectangle and two semicircles.