TW201419559A - Solar cell with thick and thin bus bar electrodes - Google Patents

Abstract

A solar cell includes a cell body, first bus bar electrodes, N second bus bar electrodes and finger electrodes. The cell body having a center line converts light into electricity and generates charges. The M first bus bar electrodes are formed on a front side of the cell body, and are substantially parallel to the center line. Each of the N second bus bar electrode(s) is formed on the front side of the cell body and is disposed between neighboring two of the first bus bar electrodes. A width of the second bus bar electrode is smaller than a width of the first bus bar electrode and is smaller than 0.05 mm and greater than or equal to 0.02 mm. The finger electrodes formed on the front side of the cell body are electrically connected to the first bus bar electrodes and the second bus bar electrode(s). A width of the finger electrode is smaller than 0.05 mm and greater than or equal to 0.02 mm. The finger electrode and the first and second bus bar electrodes collect the charges for output.

Description

Solar cell with thick bus bar electrodes

The present invention relates to a solar cell, and more particularly to a solar cell having a thick bus bar electrode.

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.

When performing screen printing, the conductive adhesive used can be divided into silver glue and aluminum glue. Silver glue is mainly used as the electrode of the battery, and is used on both sides of the battery, and the aluminum glue is printed on the back surface of the silver electrode on the ruthenium substrate. Thereafter, the ruthenium substrate is printed and sintered to increase the battery efficiency as a back surface electric field. The cost of silver glue is higher than that of aluminum glue.

The smaller the area where the solar cell is shielded, the higher the power generation efficiency. However, limited by the traditional screen printing technology (including the limitations of screen printers, screens and glue), the width of the electrodes of conventional solar cells is more than 0.5mm, because it is necessary to avoid broken or dark finger lines ( Broken or dark fingerlines), which can be seen from the electroluminescence image and the loss of power generation. In this way, in order to achieve effective harvest Collecting charge, reducing shading area, avoiding broken or dark finger lines can only adjust the width and spacing of the electrodes. For example, if a product uses two or three busbar electrodes, the total length of the points on the finger electrodes between the busbar electrodes transmitted to the busbar electrodes is still quite long, and when broken or dark When the finger line is present, the total length will be longer, which is not conducive to the efficiency of the solar cell.

An object of the present invention is to provide a solar cell having a thick bus bar electrode which can improve the power generation efficiency of the solar cell.

To achieve the above object, the present invention provides a solar cell comprising a battery body, M first bus bar electrodes, N second bus bar electrodes, and a plurality of finger electrodes. The battery body converts light energy into electrical energy to generate a plurality of charges and has a centerline located in the center of the battery body. The M first bus bars are formed on one of the front faces of the battery body and substantially parallel to the center line, and M is a positive integer greater than or equal to 2. N second bus bar electrodes are formed on the front surface of the battery body, and each of the second bus bar electrodes is located between adjacent ones of the M first bus bar electrodes, and the width of the second bus bar electrode is smaller than the first bus bar The width of the electrode, and the width of the second bus bar electrode is less than 0.05 mm and greater than or equal to 0.02 mm, and N is a positive integer greater than or equal to 1. A plurality of finger electrodes are formed on the front surface of the battery body and electrically connected to the first bus bar electrode and the second bus bar electrode. The width of the finger electrodes is less than 0.05 mm and greater than or equal to 0.02 mm. Finger electrode, first bus electrode and second sink The row of electrodes collects charge for output.

According to the above embodiment of the present invention, another method of arranging the electrodes can be provided, the shielding area of the electrodes is reduced, the charge and current of the solar cells are improved, and the adverse effects caused by the bad electrodes are reduced, thereby improving the power generation efficiency of the solar cells.

In order to make the above description of the present invention more comprehensible, a preferred embodiment will be described below in detail with reference to the accompanying drawings.

1 shows a top view of a solar cell 1 in accordance with an embodiment of the present invention. Figure 2 shows a bottom view of a solar cell 1 in accordance with an embodiment of the present invention. 3A and 3B show cross-sectional views along lines 3A-3A and 3B-3B of Fig. 1, respectively. As shown in FIGS. 1 to 3B, the solar cell 1 of the present embodiment includes a battery body 10, M first bus bar electrodes 20 (for example, 20L, 20M, 20R), and N second bus bar electrodes 25 (for example, 25L, 25R) and a plurality of finger electrodes 30. The solar cell can be a single crystal, polycrystalline or thin film solar cell.

The battery body 10 converts light energy into electrical energy to generate a plurality of charges, and has a center line 10C, and the center line 10C is located at the center of the battery body 10. In one example, the centerline 10C is a symmetrical line that can divide the battery body 10 into two halves, which is an imaginary line, a non-solid cutting line. In this embodiment, the battery body 10 includes a substrate 11 including a first type semiconductor layer 11A and a second type semiconductor layer 11B. For example, a P (or N) type germanium substrate (as a second type semiconductor layer) may be used to form an N (or P) type semiconductor layer (as an N (or P) type semiconductor) by doping. Layer); or, you can use a wide variety of Deposition techniques, layer by layer, grow P-type or N-type materials. In addition, the solar cell 1 further includes an anti-reflection layer 12 on the first type semiconductor layer 11A of the substrate 11. The first and second bus electrodes 20 and 25 and the finger electrodes 30 penetrate the anti-reflection layer 12 And electrically connected to the first type semiconductor layer 11A. The anti-reflection layer 12 provides an anti-reflection effect, and light incident on the anti-reflection layer 12 is not reflected to improve the utilization of light.

The M first bus bar electrodes 20L, 20M, 20R are formed on one front surface 10A of the battery body 10, and are substantially parallel to the center line 10C, and M is a positive integer greater than or equal to 2. In this example, M is equal to 3.

N second bus bar electrodes 25L, 25R are formed on the front surface 10A of the battery body 10, and each of the N second bus bar electrodes 25L, 25R is located adjacent to the adjacent ones of the M first bus bar electrodes 20L, 20M, 20R. The width of the second bus bar electrodes 25L, 25R is smaller than the width of the first bus bar electrodes 20L, 20M, 20R. Therefore, the solar cell 1 has bus bar electrodes 20 and 25 having different thicknesses. Further, the width of the second bus bar electrodes 25L, 25R is less than 0.05 mm and greater than or equal to 0.02 mm, preferably small, 0.05 mm and greater than or equal to 0.03 mm, and N is a positive integer greater than or equal to 1. In this example, N is equal to 2. That is, a second bus bar electrode 25 is disposed between the adjacent first bus bar electrodes 20.

A plurality of finger electrodes 30 are formed on the front surface 10A of the battery body 10, and are electrically connected to the M first bus bar electrodes 20L, 20M, 20R and the N second bus bar electrodes 25L, 25R, and a plurality of finger electrodes, The M first bus bars electrodes 20L, 20M, 20R and the N second bus bar electrodes 25L, 25R collect a plurality of charges for output. The width of the finger electrode 30 is less than 0.05 mm and greater than or equal to 0.02 mm. Therefore, the widths of the finger electrodes 30 and the second bus bar electrodes 25 can be designed to be the same. The finger electrode 30 is formed on the front surface 10A of the battery body 10 and is electrically connected to the three first bus bar electrodes 20. The angle between the finger electrode 30 and the first bus bar electrode 20 is equal to 90 degrees, although it can of course be designed to be not equal to 90 degrees to provide a visual or other effect. The plurality of finger electrodes 30, the three first bus bar electrodes 20, and the two second bus bar electrodes 25 collect a plurality of charges for output. In the present embodiment, the first bus bar electrode 20 may also be referred to as a main bus bar electrode, and the second bus bar electrode 25 may also be referred to as an auxiliary bus bar electrode.

In addition, the solar cell 1 may further include three back electrodes 40 and a back metal layer 50. The back surface electrode 40 is formed on one back surface 10B of the battery body 10 and is electrically connected to the second type semiconductor layer 11B. The back metal layer 50 is formed on the back surface 10B of the battery body 10, and the back surface electrodes 40 penetrate the back metal layer 50 and are electrically connected to the second type semiconductor layer 11B. The back electrodes 40 are opposite to the first and second bus electrodes 20, 25, respectively, through the battery body 10. The advantage of such an arrangement is that when a plurality of solar cells are connected in series or in parallel, the first bus bar electrode on the front side of one solar cell can be aligned to the back electrode on the back side of the other solar cell.

In addition, the solar cell 1 may further include a peripheral electrode 60 formed on the front surface 10A of the battery body 10 and surrounding and electrically connected to the first and second bus bar electrodes 20, 25 and the finger electrodes 30, Conducive to the collection and transmission of charge. In the present example, the peripheral electrode 60 is substantially parallel to the periphery of the battery body 10, and therefore, some portions of the peripheral electricity The pole 60 is parallel to the busbar electrodes 20 and 25, and some portions of the peripheral electrode 60 are perpendicular to the busbar electrodes 20 and 25, as shown in FIG.

It should be noted that the line 3B-3B of FIG. 1 has the cut-off bus electrodes 20 and 25 and the peripheral electrode 60, but the finger electrode 30 is not cut, and the line 3A-3A of FIG. 1 has the cut-off bus electrode 20 And 25, the peripheral electrode 60 and the finger electrode 30. So Figures 3A and 3B will be slightly different, as shown.

Other variations of the solar cell will be described below with reference to the drawings. 4A to 4H are plan views showing other examples of solar cells according to an embodiment of the present invention.

As shown in FIG. 4A, the present example is similar to the example of FIG. 1, except that a plurality of second bus bar electrodes 25 are disposed between adjacent ones of the first bus bar electrodes 20 of the present example, such as two. The second bus bar electrode 25L and the two second bus bar electrodes 25R are parallel to each other. The advantage of such a configuration is that the paths for transferring the charge on the finger electrodes 30 to the first bus bar electrode 20 and the second bus bar electrode 25 can be diversified, reducing the adverse effects caused by the broken finger electrodes 30 in the process.

As shown in FIG. 4B, the present example is similar to the example of FIG. 1, except that a plurality of second bus bar electrodes 25 are disposed between adjacent ones of the first bus bar electrodes 20 of the present example, and the same The two bus bar electrodes 25 are staggered with each other, such as two staggered second bus bar electrodes 25L and two staggered second bus bar electrodes 25R. The advantage of such a configuration is that the path of the charge on the finger electrode 30 to the first bus bar electrode 20 and the second bus bar electrode 25 can be diversified, and the disconnection finger shape on the process can be reduced. The adverse effects caused by the electrode 30.

As shown in FIG. 4C, this example is similar to the example of FIG. 1, except that the example has only two first bus bar electrodes 20, such as 20L and 20R, but two second bus bar electrodes 25, such as It is 25L and 25R. The advantage of such a configuration is that the second bus bar electrode 25 can be utilized to compensate for the shortage of the first bus bar electrode 20, achieving the power generation efficiency of the configuration of the two main bus bar electrodes 20.

As shown in FIG. 4D, the present example is similar to the example of FIG. 1, except that a plurality of second bus bar electrodes 25 are disposed between adjacent ones of the first bus bar electrodes 20 of the present example, and the second The bus bar electrodes 25 are staggered with each other and directly connected to the first bus bar electrodes 20. The advantage of such a configuration is that the first bus bar electrode 20 can be integrally connected by the second bus bar electrode 25 to diversify the charge transmission path and reduce the influence of the defective finger electrode 30.

As shown in FIG. 4E, this example is similar to the example of FIG. 4C except that the second bus bar electrodes 25 of the present example are staggered with each other. This can achieve an effect similar to the example of Fig. 4B.

As shown in FIG. 4F, this example is similar to the example of FIG. 4C except that the second bus bar electrodes 25 of the present example are parallel to each other but not parallel to the first bus bar electrode 20. This gives designers a variety of options.

As shown in FIG. 4G, this example is similar to the example of FIG. 4A except that the pattern of the second bus bar electrode 25L1/25L2/25R1/25R2 is a broken line. In the dashed line of the second bus bar electrode 25L1/25L2, the respective line segments 25L1D/25L2D of the broken line are connected between the adjacent finger electrodes 30. In addition, the line segments 25L1D of the second bus bar electrodes 25 The 25L2D is staggered from each other, that is, between the first bus electrodes 20L and 20M, and only one line segment 25L1D/25L2D is connected between the two adjacent two finger electrodes 30.

As shown in Fig. 4H, this example is similar to the example of Fig. 4G except that the pitch of the second bus bar electrodes 25L1 and 25L2 in the left half is reduced to form a strip-like structure like a zigzag. In addition, the connection manner of the second bus bar electrodes 25R1 and 25R2 in the right half is also changed, that is, there is no dotted line segment of the second bus bar electrode 25 between the adjacent adjacent finger electrodes 30. . Therefore, the connecting medium of the adjacent finger electrodes 30 is sequentially (25R1D)-->(none)-->(25R2D), so that the shadowing effect of the electrodes can be reduced without greatly affecting the effect of charge transfer.

The configuration of the various patterns of the above second bus bar electrode 25 is for illustrative purposes only, and does not particularly limit the scope of the present invention. The widths of these second bus bar electrodes 25 may be identical, and may of course be different or partially different from one another. These second bus bar electrodes 25 may be parallel to each other, parallel to the first bus bar electrode 20, not parallel to each other or not parallel to the first bus bar electrode 20. The spacing distances of these second bus bar electrodes 25 may be equal or unequal. The pattern of these second bus bar electrodes 25 may be a straight line, an arc or other curve. The bus bar electrodes 20 or 25 may be symmetrical or asymmetrical with respect to the center line 10C. The above various changes can achieve an effect of reducing the light-shielding area and thus increasing the current and power generation efficiency with respect to the conventional technology. These second bus bar electrodes 25 can be fabricated by single or multiple printing to produce a higher aspect ratio and a narrower finger electrode having a low resistance.

The inventor of the case discovered DuPont's PV17F and PV18X series or The Heraeus 9600 provides the glue for the electrodes required for the inventive concept of the present invention. The configuration of the second bus bar electrode is such that once the broken or dark finger electrode is formed, a bypass route can be provided to connect to the nearby first bus bar electrode. Thereby, the efficiency of charge collection can be provided, and the current and power generation efficiency can be improved.

Fig. 5 is a view showing a partial connection state of the solar cell module 100 according to the present invention. As shown in FIG. 5, the present invention also provides a solar cell module 100 comprising a plurality of solar cells 1 as described above and a plurality of conductive strips 70. The number of conductive strips 70 depends on the number of busbar electrodes 20 to be soldered or the number of backside electrodes 40. The conductive strips 70 electrically connect the busbar electrodes 20 of one of the solar cells 1 to the back electrodes 40 of the other of the solar cells 1, respectively, and the conductive strips 70 are soldered to the same. The bus bar electrode 20 and the back electrode 40 are on the bus bar. As for the second bus bar electrode 25, it is not necessary to solder to the conductive tape 70, but it may be soldered to the conductive tape 70 as needed.

With the above embodiments of the present invention, another method of arranging electrodes can be provided, which reduces the shielding area of the electrodes, increases the charge and current of the solar cells, and reduces the adverse effects caused by the bad electrodes, thereby improving the power generation efficiency of the solar cells.

The specific embodiments of the present invention are intended to be illustrative only and not to limit the invention to the above embodiments, without departing from the spirit of the invention and the following claims. The scope of the invention and the various changes made are within the scope of the invention.

1‧‧‧Solar battery

Lines 3A-3A, 3B-3B‧‧

10‧‧‧ battery body

10A‧‧‧ positive

10B‧‧‧Back

10C‧‧‧ center line

11‧‧‧Substrate

11A‧‧‧first type semiconductor layer

11B‧‧‧Second type semiconductor layer

12‧‧‧Anti-reflective layer

20, 20L, 20M, 20R‧‧‧ first bus bar electrode

25, 25L, 25R, 25L1, 25L2, 25R1, 25R2‧‧‧ second bus bar electrode

25L1D, 25L2D‧‧‧ segments

30‧‧‧Finger electrode

40‧‧‧Back electrode

50‧‧‧Back metal layer

60‧‧‧ peripheral electrodes

70‧‧‧ Conductive tape

100‧‧‧Solar battery module

1 shows a top view of a solar cell in accordance with an embodiment of the present invention.

2 shows a bottom view of a solar cell in accordance with an embodiment of the present invention.

3A and 3B show cross-sectional views along lines 3A-3A and 3B-3B of Fig. 1, respectively.

4A to 4H are plan views showing other examples of solar cells according to an embodiment of the present invention.

Fig. 5 is a view showing a state of partial connection of a solar cell module according to the present invention.

1‧‧‧Solar battery

Lines 3A-3A, 3B-3B‧‧

10‧‧‧ battery body

10A‧‧‧ positive

10C‧‧‧ center line

12‧‧‧Anti-reflective layer

20, 20L, 20M, 20R‧‧‧ first bus bar electrode

25, 25L, 25R‧‧‧ second bus bar electrode

30‧‧‧Finger electrode

60‧‧‧ peripheral electrodes

Claims (12)

A solar cell comprising: a battery body, converting light energy into electrical energy to generate a plurality of charges, and having a center line located at a center of the battery body; M first bus bar electrodes formed at the a front side of the battery body, and substantially parallel to the center line, M is a positive integer greater than or equal to 2; N second bus bar electrodes are formed on the front surface of the battery body, each of the N second The bus bar electrode is located between adjacent ones of the M first bus bar electrodes, the width of the second bus bar electrode is smaller than the width of the first bus bar electrode, and the width of the second bus bar electrode is less than 0.05 mm And greater than or equal to 0.02 mm, N is a positive integer greater than or equal to 1; and a plurality of finger electrodes are formed on the front surface of the battery body and electrically connected to the M first bus bar electrodes and the N strips a second bus bar electrode, each of the finger electrodes having a width of less than 0.05 mm and greater than or equal to 0.02 mm, and the plurality of finger electrodes, the M first bus bar electrodes, and the N second bus bar electrodes are collected A charge is available for output. The solar cell of claim 1, wherein the battery body comprises a substrate, the substrate comprises a first type semiconductor layer and a second type semiconductor layer, and the solar cell further comprises: an anti-reflection layer, On the first type semiconductor layer of the substrate, the first and second bus bar electrodes and the finger electrodes penetrate the anti-reflection layer and are electrically connected to the first type semiconductor layer. Such as the solar cell described in claim 1 of the patent scope, The method includes a plurality of back electrodes formed on a back surface of the battery body and electrically connected to the second semiconductor layer, and a back metal layer formed on the back surface of the battery body, the back electrodes penetrating the back surface A metal layer is electrically connected to the second type semiconductor layer. The solar cell of claim 3, wherein the back electrodes are opposite to the first and second bus electrodes respectively through the battery body. The solar cell of claim 1, further comprising: a peripheral electrode formed on the front surface of the battery body, and surrounding and electrically connected to the first and second bus bar electrodes and the fingers Shape electrode. The solar cell of claim 1, wherein a second bus bar electrode is disposed between adjacent ones of the first bus bar electrodes. The solar cell of claim 1, wherein a plurality of second bus bar electrodes are disposed between the adjacent first bus bar electrodes, and the second bus bar electrodes are parallel to each other. The solar cell of claim 1, wherein a plurality of second bus bar electrodes are disposed between the adjacent first bus bar electrodes, and the second bus bar electrodes are staggered with each other. The solar cell of claim 1, wherein a plurality of second confluences are disposed between adjacent ones of the first bus electrodes The drain electrodes are staggered with each other and directly connected to the first bus bar electrodes. The solar cell of claim 1, wherein the pattern of the second bus bar electrode is a dashed line, and each line segment of the dashed line is connected between adjacent ones of the finger electrodes. The solar cell of claim 1, wherein the pattern of each of the second bus bar electrodes is a broken line, and each line segment of the broken line is connected between adjacent ones of the finger electrodes, and the second The line segments of the bus bar electrodes are staggered from each other. The solar cell of claim 11, wherein a portion of the adjacent one of the finger electrodes is absent from the dotted line of the second bus bar electrode.