Patent Description:
A solar cell is a semiconductor device capable of converting light energy to electric energy. A solar cell that includes a back side connection layer containing current collecting lines and collection busbars is described, for example, in <CIT>. Relatively low production costs and relatively high energy conversion efficiency have always been the goals pursued by the photovoltaic industry. For a conventional solar cell, an emitter contact electrode and a base contact electrode of the solar cell are respectively located on two opposite sides of the solar cell. A front side of the cell is a light-receiving surface. The coverage of a front metal emitter contact electrode inevitably causes part of incident sunlight to be reflected and blocked by a metal electrode, resulting in part of optical loss. A coverage area of a front metal electrode of an ordinary crystalline silicon solar cell is about <NUM>%. Therefore, energy conversion efficiency of the cell may be directly enhanced by reducing the front coverage of the metal electrode.

In view of the above situation, a back contact solar cell is introduced. A back contact solar cell is a cell in which an emitter and a base contact electrode are both disposed on the back side (a non-light-receiving surface) of the cell. A light-receiving surface of the cell is not shielded by any metal electrode, thereby effectively increasing the short-circuit current of the cell. In addition, relatively wide metal fingers are allowed to be disposed on the back side to reduce a serial resistance, thereby increasing the fill factor. Moreover, the cell with the front not shielded not only has high conversion efficiency, but also looks more beautiful. In addition, a module of an all back-contact electrode is easy to assemble.

For the back contact solar cell, an electrode pattern design is a core technology of the cell. Three electrode pattern designs of the existing back contact solar cell are as follows.

Therefore, it has always been one of the key research problems for those skilled in the art to design an electrode structure of a back contact cell, a back contact cell, a back contact cell module, and a back contact cell system to solve the above problems.

The disclosure provides an electrode structure of a back contact cell, to solve technical problems of high costs, low reliability, and poor photoelectric conversion performance of the existing back contact solar cell.

An electrode structure of a back contact cell is provided; the back contact cell comprises a first polarity region, a second polarity region, and a first edge, and the electrode structure comprises:.

In the present invention, the second fingers comprise first bent.

fingers between the first busbar and the first pad points, the first bent fingers are respectively bent toward the first busbar and the first pad points, and are in contact with neither the first busbar nor the first pad points, or the first bent fingers are bent toward the first busbar and are not in contact with the first busbar, or the first bent fingers are bent toward the first pad points and are not in contact with the first pad points.

In a class of this embodiment, each of the first bent fingers passes through at least one of the first fingers.

In a class of this embodiment, a center line of each of the first connection electrodes and a center line of each of the first pad points are not on a same straight line.

In a class of this embodiment, the electrode structure further comprises third fingers respectively connected to the first busbar and the first pad points. The third fingers are disposed adjacent to the first connection electrodes, and a width of each of the third fingers is less than a width of each of the first connection electrodes.

In a class of this embodiment, each of the second fingers is covered with a first insulating material in a partial region of a center line of each of the first pad points.

In a class of this embodiment, the distance between the first busbar and the first edge ranges from <NUM> to <NUM>.

In a class of this embodiment, the distance between each of the first pad points and the first edge ranges from <NUM> to <NUM>.

In a class of this embodiment, the electrode structure further comprises:.

In a class of this embodiment, the first fingers comprise second bent fingers between the second busbar and the second pad points, the second bent fingers are respectively bent toward the second busbar and the second pad points and are in contact with neither the second busbar nor the second pad points, or the second bent fingers are bent toward the second busbar and are not in contact with the second busbar, or the second bent fingers are bent toward the second pad points and are not in contact with the second pad points.

In a class of this embodiment, each of the second bent fingers passes through at least one of the second fingers.

In a class of this embodiment, a center line of each of the second connection electrodes and a center line of each of the second pad points are on a same straight line.

In a class of this embodiment, the electrode structure further comprises fourth fingers, respectively connected to the second busbar and the second pad points. The fourth fingers are disposed adjacent to the second connection electrodes, and a width of each of the fourth fingers is less than a width of each of the second connection electrodes.

In a class of this embodiment, each of the first fingers is covered with a second insulating material in a partial region of a center line of each of the second pad points.

In a class of this embodiment, the distance between the second busbar and the second edge ranges from <NUM> to <NUM>.

In a class of this embodiment, the distance between each of the second pad points and the second edge ranges from <NUM> to <NUM>.

The disclosure further provides a back contact cell. The back contact cell comprises the electrode structure described above, and the electrode structure is disposed on a back surface (a non-light-receiving surface) of the back contact cell.

The disclosure further provides a back contact cell module. The back contact cell module comprises the back contact cell described above.

The disclosure further provides a back contact cell system. The back contact cell system comprises the back contact cell module described above.

The beneficial effect of the disclosure is that the electrode structure comprises the first fingers, the second fingers, the first busbar, the first pad points, and the first connection electrodes respectively connected to the first busbar and the first pad points, so as to realize collection of currents. There is no need to print insulation paste in a large area of the electrode structure. The first pad points and the first busbar are not simultaneously disposed on the first edge of the back contact cell, and the photo-generated electrons and holes are not required to cross a long distance to reach the region having the opposite polarity. In this way, the electrode structure can improve the reliability, reduce the costs, increase the product yield, and ensure excellent photoelectric conversion efficiency.

To make objectives, technical solutions, and advantages of the disclosure clearer and more comprehensible, the following further describes the disclosure in detail with reference to the accompanying drawings and embodiments. It should be understood that the embodiments herein are provided for describing the disclosure and not intended to limit the disclosure.

The disclosure provides an electrode structure of a back contact cell according to the appended independent claim <NUM>. The electrode structure comprises first fingers, second fingers, a first busbar, first pad points, and first connection electrodes respectively connected to the first busbar and the first pad points. The first fingers collect currents in a first polarity region, and the currents flow to the first busbar through the first pad points and the first connection electrodes, thereby realizing the collection of the currents. There is no need to print insulation paste in a large area of the electrode structure. The first pad points and the first busbar are not simultaneously disposed on the first edge of the back contact cell, and the photo-generated electrons and holes are not required to cross a long distance to reach the region having an opposite polarity. In this way, the electrode structure can improve the reliability, reduce the costs, increase the product yield, and ensure excellent photoelectric conversion efficiency.

Referring to <FIG>, Example <NUM>, which is not part of the present invention, provides an electrode structure of a back contact cell. The electrode structure comprises:.

A distance between each of the first pad points <NUM> and the first edge is greater than a distance between the first busbar <NUM> and the first edge.

The first finger <NUM> is configured to collect currents of the first polarity region, and the second finger <NUM> is configured to collect currents of the second polarity region. If the polarities of the first finger <NUM> and the second finger <NUM> are opposite, the polarities of the first polarity region and the second polarity region are opposite as well. For example, if the first finger <NUM> is a positive electrode finger and is configured to collect positive electrode currents in a positive electrode region, then the second finger <NUM> is a negative electrode finger and is configured to collect negative electrode currents in a negative electrode region. Alternatively, if the first finger <NUM> is the negative electrode finger and is configured to collect negative electrode currents in the negative electrode region, then the second finger <NUM> is the positive electrode finger and is configured to collect positive electrode currents in the positive electrode region. The positive electrode finger is disposed in a P-type doped region of the back contact cell, and the negative electrode finger is disposed in an N-type doped region of the back contact cell.

Referring to <FIG>, for the convenience of identification, the polarities of the first fingers <NUM> in a blackened part is the same, the polarities of the second fingers <NUM> in an unprinted part are the same, and the polarities of the first fingers <NUM> and the second fingers <NUM> are opposite. On the other hand, the first pad points <NUM>, the first connection electrodes <NUM>, and the first busbar <NUM> in the blackened part have the same polarity as the first fingers <NUM>.

The first fingers <NUM> and the second fingers <NUM> are alternately disposed, and the first fingers <NUM> and the second fingers <NUM> are all parallel to an edge line of the back contact cell. For example, referring to <FIG>, the first fingers <NUM> and the second fingers <NUM> are alternately disposed in a vertical direction, and the first fingers <NUM> and the second fingers <NUM> are both parallel to an upper edge line and a lower edge line of the back contact cell. The back contact cell is substantially in a rectangular shape. The back contact cell that is substantially in the rectangular shape may be, for example, in a square shape, or may be in another rectangular shape, and may have standard corners, cut corners, or rounded corners. The back contact cell is designed according to actual production requirements, which is not specifically limited herein. Quantities of the first fingers <NUM> and the second fingers <NUM> of the back contact cell are determined according to an actual size of the back contact cell and widths of the first fingers <NUM> and the second fingers <NUM> and a distance therebetween, which are not specifically limited herein.

Further, the first finger <NUM> or the second finger <NUM> is an aluminum finger, a silver finger, a copper finger, or a silver-coated copper finger. It may be understood that, in this embodiment of the disclosure, a same metal type or different metal types of fingers may be selected as the first finger <NUM> and the second finger <NUM> of the back contact cell. For example, the aluminum finger is selected as the first finger <NUM> and the second finger <NUM>, or the aluminum finger is selected as the first finger <NUM>, and the silver finger is selected as the second finger <NUM>. When the first finger <NUM> or the second finger <NUM> is the aluminum finger or the silver finger, the first finger or the second finger is printed on the doped region of the back contact cell by silk-screen printing. When the first finger <NUM> or the second finger <NUM> is the copper finger, the first finger or the second finger is plated on the doped region of the back contact cell by electroplating, evaporation, or the like.

The distance between each of the first pad points <NUM> and the first edge is greater than the distance between the first busbar <NUM> and the first edge. For example, referring to <FIG>, a distance between a leftmost side of the first pad points <NUM> and an edge of a leftmost side of the back contact cell is greater than a distance between a leftmost side of the first busbar <NUM> and the edge of the leftmost side of the back contact cell.

In this example, the distance between the first busbar <NUM> and the first edge ranges from <NUM> to <NUM>, which herein is the distance between an edge of the first busbar <NUM> close to the first edge and the first edge. For example, the distance between the first busbar <NUM> and the first edge is <NUM>, <NUM>, <NUM>, <NUM>, or other parameter values from <NUM> to <NUM>. The distance between each of the first pad points <NUM> and the first edge ranges from <NUM> to <NUM>, which herein is the distance between an edge of the first pad point <NUM> close to the first edge and the first edge. For example, the distance between the first pad point <NUM> and the first edge is <NUM>, <NUM>, <NUM>, <NUM>, or other parameter values from <NUM> to <NUM>, but the distance between the first pad point <NUM> and the first edge is greater than the distance between the first busbar <NUM> and the first edge.

The first pad point <NUM> is disposed away from the first busbar <NUM>, and the connection between the first pad point <NUM> and the first busbar <NUM> is realized by using the first connection electrode <NUM>. However, the first busbar <NUM> is disposed on the first edge of the back contact cell, and the first pad point <NUM> is disposed away from the first edge of the back contact cell. During the current collection, the first finger <NUM> collects the currents of the first polarity region, then transmits the collected currents to the first pad point <NUM>, and then transmits the collected currents from the first pad point <NUM> to the first busbar <NUM> through the first connection electrode <NUM> to complete the collection of the currents. Compared with the first electrode pattern design in the background art, there is no need to print the insulation paste in a large area of the electrode structure of the disclosure, and high-temperature paste may be selected for the first pad point <NUM> and the first busbar <NUM>, thereby reducing the costs and ensuring the reliability. In addition, the heights of the first pad point <NUM> and the first busbar <NUM> are not required to be too high, so that the paste consumption is reduced. Moreover, since there is no need to print the insulation paste in a large area, the problem of poor adhesion with some paste will not occur, thereby reducing the difficulty of mass production. Compared with the second electrode pattern design in the background art, the first busbar <NUM> is located at the first edge of the back contact cell, and the first pad point <NUM> is away from the first edge of the back contact cell, so as to avoid stress concentration in the welding process, thereby improving the yield of the module and improving the reliability of the module. Compared with the third electrode pattern design in the background art, the photo-generated electrons and holes are not required to cross a long distance to reach the region having the opposite polarity, to collect the currents, thereby fully ensuring relatively high photoelectric conversion efficiency.

On the basis of the above described example <NUM>, the second finger <NUM> of Embodiment <NUM> comprises first bent fingers between the first busbar <NUM> and the first pad points <NUM>, the first bent fingers are respectively bent toward the first busbar <NUM> and the first pad points <NUM> and are in contact with neither the first busbar <NUM> nor the first pad points <NUM>, or the first bent fingers are bent toward the first busbar <NUM> and are not in contact with the first busbar <NUM>, or the first bent fingers are bent toward the first pad points <NUM> and are not in contact with the first pad points <NUM>.

Referring to <FIG>, the first bent fingers are defined as first bent sub-fingers <NUM>. The first fingers <NUM> comprise first pad point connection fingers <NUM> connected to the first pad points <NUM> and first busbar connection fingers <NUM> connected to the first busbar <NUM>. The first pad point connection fingers <NUM> are disposed adjacent to the first busbar connection fingers <NUM>, and a gap is formed therebetween. The first bent sub-fingers <NUM> pass through the gap, are respectively bent toward the first busbar <NUM> and the first pad points <NUM>, and are in contact with neither the first busbar <NUM> nor the first pad points <NUM>. In other implementations, the first pad point connection fingers <NUM> and/or the first busbar connection fingers <NUM> may be omitted. However, through arrangement of the first pad point connection fingers <NUM> and/or the first busbar connection fingers <NUM>, the fingers may be disposed more uniformly, to cause the current collection in a small region to be implemented.

Referring to <FIG>, the first bent fingers are defined as second bent sub-fingers <NUM>. The first fingers <NUM> comprise second busbar connection fingers <NUM> connected to the first busbar <NUM>, and a gap is formed between the second busbar connection fingers <NUM> and the first pad points <NUM>. The second bent sub-fingers <NUM> pass through the gap, are bent toward the first busbar <NUM>, and are not in contact with the first busbar <NUM>. In other implementations, the pad point connection finger may be added, so as to achieve a more uniform arrangement of the fingers and cause the current collection in a small region to be implemented.

Referring to <FIG>, the first bent fingers are defined as third bent sub-fingers <NUM>. The first fingers <NUM> comprise second pad point connection fingers <NUM> connected to the first pad points <NUM>. A gap is formed between the second pad point connection fingers <NUM> and the first busbar <NUM>, and the third bent sub-fingers <NUM> pass through the gap, are bent toward the first pad points <NUM>, and are not in contact with the first pad points <NUM>. In other implementations, the busbar connection finger may be added, so as to achieve a more uniform arrangement of the fingers and cause the current collection in a small region to be implemented.

In this embodiment of the disclosure, a length of the first bent finger is determined according to a size of an available region. The first bent fingers form divergent extension, so as to make full use of the region where the currents can be collected, thereby further improving the capability of current collection.

Further, based on the above implementations, each of the first bent fingers passes through at least one of the first fingers <NUM>. A plurality of first fingers <NUM> may be disposed in the region between or near the first pad points <NUM> and the first busbar <NUM>, and a plurality of gaps are formed by arranging the first fingers <NUM>. In this way, the first bent fingers may pass through the gaps in sequence, and then form divergent extension after passing through each of the gaps, thereby further improving the capability of current collection.

Referring to <FIG>, on the basis of Embodiment <NUM>, *,- a center line of each of the first connection electrodes <NUM> and a center line of each of the first pad points <NUM> in Embodiment <NUM> are not on the same straight line.

In this embodiment of the disclosure, the center line of the first pad point <NUM> is located on a setting line of the second fingers <NUM>, and the polarities of the first pad points <NUM> and the second fingers <NUM> are opposite. For example, the first pad point <NUM> has a positive polarity, and the second finger <NUM> has a negative polarity. Therefore, the center line of the first connection electrode <NUM> is disposed offset from the center line of the first pad point <NUM>. That is, the center line of the first connection electrode <NUM> is disposed offset from the setting line of the second finger <NUM>, so that the center line of the first connection electrode <NUM> may be disposed on the setting line of the first finger <NUM>. The polarities of the first connection electrode <NUM> and the first finger <NUM> are the same, thereby achieving a more uniform distribution of fingers having opposite polarities in the region adjacent to the first pad point <NUM>, and further improving the capability of current collection.

Referring to <FIG>, on the basis of Embodiment <NUM>, the electrode structure of Embodiment <NUM> further comprises a third finger <NUM> respectively connected to the first busbar <NUM> and the first pad point <NUM>. The third finger <NUM> is disposed adjacent to the first connection electrode <NUM>, and a width of the third finger <NUM> is less than a width of the first connection electrode <NUM>.

In this embodiment of the disclosure, under normal circumstances, the first connection electrode <NUM> is not in contact with a substrate of the back contact cell. At this point, the photo-generated electrons and holes in the region where the first connection electrode <NUM> is located cannot be effectively collected. Therefore, the third finger <NUM> is disposed in the region adjacent to the first connection electrode <NUM>, and the third finger <NUM> may be in contact with the substrate, thereby further improving the capability of current collection.

Referring to <FIG>, on the basis of the example <NUM>, the second finger <NUM> of Embodiment <NUM> is covered with a first insulating material <NUM> in a partial region located on a center line of the first pad point <NUM>.

The first insulating material <NUM> may be covered with the insulation paste, where only the second finger <NUM> is covered with the insulation paste in the partial region located on the center line of the first pad point <NUM>, which will not increase product costs. Certainly, the first insulating material <NUM> may also adopt other implementations, as long as the purpose of insulation can be achieved.

During the welding of the ribbon, under the insulating effect of the first insulating material <NUM>, the second finger <NUM> may be prevented from coming into contact with the ribbon in the partial region located on the center line of the first pad point <NUM>, thereby effectively avoiding occurrence of short circuits. In addition, the first insulating material <NUM> is made after the first pad point <NUM> and the first busbar <NUM> are formed, and does not affect the selection of electrode materials for the first pad point <NUM> and the first busbar <NUM>.

As shown in <FIG>, on the basis of the example <NUM>, the electrode structure of example <NUM>, which is not part of the present invention, further comprises:.

A distance between each of the second pad points <NUM> and the second edge is greater than a distance between the second busbar <NUM> and the second edge.

Referring to <FIG>, the first edge is a leftmost side of the back contact cell, and the second edge is a rightmost side of the back contact cell. A plurality of pad points is also disposed between the first pad point <NUM> and the second pad point <NUM>. The pad points may be disposed on the same straight line as the busbar having a same polarity.

The distance between each of the second pad points <NUM> and the second edge is greater than the distance between the second busbar <NUM> and the second edge. For example, referring to <FIG>, a distance between a leftmost side of the second pad points <NUM> and an edge of the leftmost side of the back contact cell is greater than a distance between a leftmost side of the second busbar <NUM> and an edge of the leftmost side of the back contact cell.

The distance between the second busbar <NUM> and the second edge ranges from <NUM> to <NUM>, which herein is the distance between an edge of the second busbar <NUM> close to the second edge and the second edge. For example, the distance between the second busbar <NUM> and the second edge is <NUM>, <NUM>, <NUM>, <NUM>, or other parameter values from <NUM> to <NUM>. The distance between each of the second pad points <NUM> and the second edge ranges from <NUM> to <NUM>, which herein is the distance between an edge of the second pad point <NUM> close to the second edge and the second edge. For example, the distance between each of the second pad points <NUM> and the second edge is <NUM>, <NUM>, <NUM>, <NUM>, or other parameter values from <NUM> to <NUM>, but the distance between each of the second pad points <NUM> and the second edge is greater than the distance between the second busbar <NUM> and the second edge.

The second pad point <NUM> is disposed away from the second busbar <NUM>, and the connection between the second pad point <NUM> and the second busbar <NUM> is realized by using the second connection electrode <NUM>. However, the second busbar <NUM> is disposed on the second edge of the back contact cell, and the second pad point <NUM> is disposed away from the second edge of the back contact cell. During the current collection, the second finger <NUM> collects the currents of the second polarity region, then transmits the collected currents to the second pad point <NUM>, and then transmits the collected currents from the second pad point <NUM> to the second busbar <NUM> through the second connection electrode <NUM> to complete the collection of the currents. Pad points, busbars, and connection electrodes respectively connected to the pad points and the busbars are disposed on edges of two ends of the back contact cell. Compared with the first electrode pattern design in the background art, there is no need to print the insulation paste in a large area, and high-temperature paste may be selected for the pad points and the busbars, thereby reducing the costs and ensuring the reliability. In addition, the heights of the pad point and the busbar are not required to be too high, so that the paste consumption is reduced. Moreover, since there is no need to print the insulation paste in a large area, the problem of poor adhesion with some paste will not occur, thereby reducing the difficulty of mass production. Compared with the second electrode pattern design in the background art, the busbars are located at the edge of the back contact cell, and the pad points are away from the edge of the back contact cell, so as to avoid stress concentration in the welding process, thereby improving the yield of the module and improving the reliability of the module. Compared with the third electrode pattern design in the background art, the photo-generated electrons and holes are not required to cross a long distance to reach the region having the opposite polarity, to collect the currents, thereby fully ensuring relatively high photoelectric conversion efficiency.

On the basis of the example <NUM>, the first finger <NUM> of the Embodiment <NUM> comprises second bent fingers located between the second busbar <NUM> and the second pad points <NUM>, the second bent fingers are respectively bent toward the second busbar <NUM> and the second pad points <NUM> and are not in contact with the second busbar <NUM> and the second pad points <NUM>, or the second bent fingers are bent toward the second busbar <NUM> and are not in contact with the second busbar <NUM>, or the second bent fingers are bent toward the second pad point <NUM> and are not in contact with the second pad points <NUM>.

Referring to <FIG>, the second bent fingers are defined as fourth bent sub-fingers <NUM>. The second fingers <NUM> comprise third pad point connection fingers <NUM> connected to the second pad points <NUM> and third busbar connection fingers <NUM> connected to the second busbar <NUM>. The third pad point connection fingers <NUM> are disposed adjacent to the third busbar connection fingers <NUM>, and a gap is formed therebetween. The fourth bent sub-fingers <NUM> pass through the gap, are respectively bent toward the second busbar <NUM> and the second pad points <NUM>, and are in contact with neither the second busbar <NUM> nor the second pad points <NUM>. In other implementations, the third pad point connection finger <NUM> and/or the third busbar connection finger <NUM> may be omitted. However, through arrangement of the third pad point connection finger <NUM> and/or the third busbar connection finger <NUM>, the fingers may be disposed more uniformly, to cause the current collection in a small region to be implemented.

Referring to <FIG>, the second bent fingers are defined as fifth bent sub-fingers <NUM>. The second fingers <NUM> comprise fourth pad point connection fingers <NUM> connected to the second pad points <NUM> and fourth busbar connection fingers <NUM> connected to the second busbar <NUM>. The fourth pad point connection fingers <NUM> are disposed adjacent to the fourth busbar connection fingers <NUM>, and a gap is formed therebetween. The fifth bent sub-fingers <NUM> pass through the gap, are respectively bent toward the second busbar <NUM>, and are not in contact with the second busbar <NUM>. In other implementations, the fourth pad point connection fingers <NUM> and/or the fourth busbar connection fingers <NUM> may be omitted. However, through arrangement of the fourth pad point connection fingers <NUM> and/or the fourth busbar connection fingers <NUM>, the fingers may be disposed more uniformly, to cause the current collection in a small region to be implemented.

Referring to <FIG>, the second bent fingers are defined as sixth bent sub-fingers <NUM>. The second fingers <NUM> comprise fifth pad point connection fingers <NUM> connected to the second pad points <NUM>. A gap is formed between the fifth pad point connection fingers <NUM> and the second busbar <NUM>, and the sixth bent sub-fingers <NUM> pass through the gap, are bent toward the second pad point <NUM>, and are not in contact with the second pad points <NUM>. In other implementations, the busbar connection finger may be added, so as to achieve a more uniform arrangement of the fingers and cause the current collection in a small region to be implemented.

In this embodiment of the disclosure, a length of the second bent finger is determined according to a size of an available region. The second bent fingers form divergent extension, so as to make full use of the region where the currents can be collected, thereby further improving the capability of current collection.

Further, based on the above implementations, each of the second bent fingers passes through at least one of the second fingers <NUM>. A plurality of second fingers <NUM> may be disposed in the region between or near the second pad point <NUM> and the second busbar <NUM>, and a plurality of gaps are formed by arranging the second fingers <NUM>. In this way, the second bent fingers may pass through the gaps in sequence, and then form divergent extension after passing through each of the gaps, thereby further improving the capability of current collection.

In combination with , the arrangement of the first bent finger and the second bent finger can be disposed on the edges of two ends of the back contact cell in different manners, and the arrangement mode of the first bent finger and the second bent finger may be selected according to an actual situation. For example, referring to <FIG>, the first edge of the back contact cell is not provided with the first bent finger, and the second edge of the back contact cell is provided with the second bent finger. The second bent fingers are respectively bent toward the second busbar <NUM> and the second pad point <NUM>.

Referring to <FIG>, on the basis of Embodiment <NUM> a center line of the second connection electrode <NUM> and a center line of the second pad point <NUM> in Embodiment <NUM> are on a same straight line.

In this embodiment of the disclosure, the center line of the second pad point <NUM> is located on a setting line of the second finger <NUM>, and the second pad point <NUM> has a same polarity as the second finger <NUM>. For example, the second pad point <NUM> has a negative polarity, and the second finger <NUM> has a negative polarity. Therefore, the center line of the second connection electrode <NUM> and the center line of the second pad point <NUM> are disposed on the same straight line, so as to dispose the center line of the second connection electrode <NUM> on the setting line of the second finger <NUM>. The second connection electrode <NUM> has the same polarity as the second finger <NUM>, thereby achieving a more uniform distribution of fingers having opposite polarities in the region adjacent to the second pad point <NUM>, and further improving the capability of current collection.

On the basis of Embodiment <NUM>, the electrode structure of Embodiment <NUM> further comprises a fourth finger <NUM> respectively connected to the second busbar <NUM> and the second pad point <NUM>. The fourth finger <NUM> is disposed adjacent to the second connection electrode <NUM>, and a width of the fourth finger <NUM> is less than a width of the second connection electrode <NUM>.

In this embodiment of the disclosure, under normal circumstances, the second connection electrode <NUM> is not in contact with a substrate of the back contact cell. At this point, the photo-generated electrons and holes in the region where the second connection electrode <NUM> is located cannot be effectively collected. Therefore, the fourth finger <NUM> is disposed in the region adjacent to the second connection electrode <NUM>, and the fourth finger <NUM> may be in contact with the substrate, thereby further improving the capability of current collection.

On the basis of the example <NUM>, the first finger <NUM> of Embodiment <NUM> is covered with a second insulating material <NUM> in a partial region located on a center line of the second pad point <NUM>.

The second insulating material <NUM> may be covered with the insulation paste, where only the first finger <NUM> is covered with the insulation paste in the partial region located on the center line of the second pad point <NUM>, which will not increase product costs. Certainly, the second insulating material <NUM> may also adopt other implementations, as long as the purpose of insulation can be achieved.

During the welding of the ribbon, under the insulating effect of the second insulating material <NUM>, the first finger <NUM> may be prevented from coming into contact with the ribbon in the partial region located on the center line of the second pad point <NUM>, thereby effectively avoiding occurrence of short circuits. In addition, the second insulating material <NUM> is made after the second pad point <NUM> and the second busbar <NUM> are formed, and does not affect the selection of electrode materials for the second pad point <NUM> and the second busbar.

Based on the embodiments and the examples described above, the modeling calculation is performed herein.

<FIG> shows an edge model diagram based on the electrode structure of <FIG>. <FIG> shows an edge model diagram based on the electrode structure of <FIG>. <FIG> shows an edge model diagram based on the electrode structure of <FIG>. <FIG> shows an edge model diagram based on the electrode structure of <FIG>.

The cell conversion efficiency is a key performance evaluation index for the back contact cell. Higher cell conversion efficiency leads to better performance, and every <NUM>% increase is a breakthrough for the industry. It can be seen that the scheme of <FIG> is adopted, the problem of module yield and reliability is solved, but the performance is greatly reduced by <NUM>%. If the scheme of <FIG> of the disclosure is adopted, the efficiency loss is reduced to <NUM>% in a case that the module yield and reliability are solved. If the optimization scheme of <FIG> of the disclosure is adopted, the efficiency loss may be reduced to <NUM>%. At present, the conversion efficiency test repeatability of the back contact cell is about ± <NUM>%, and the efficiency loss is too low to be monitored and can be ignored.

Embodiment <NUM> provides a back contact cell. The back contact cell comprises the electrode structure described in the above embodiments, and the electrode structure is disposed on a backlight surface of the back contact cell.

In the electrode structure provided in this embodiment of the disclosure, the first pad point <NUM> is disposed away from the first busbar <NUM>, and the connection between the first pad point <NUM> and the first busbar <NUM> is realized by using the first connection electrode <NUM>. However, the first busbar <NUM> is disposed on the first edge of the back contact cell, and the first pad point <NUM> is disposed away from the first edge of the back contact cell. During the current collection, the first finger <NUM> collects the currents of the first polarity region, then transmits the collected currents to the first pad point <NUM>, and then transmits the collected currents from the first pad point <NUM> to the first busbar <NUM> through the first connection electrode <NUM> to complete the collection of the currents. Compared with the first electrode pattern design in the background art, there is no need to print the insulation paste in a large area of the electrode structure of the disclosure, and high-temperature paste may be selected for the first pad point <NUM> and the first busbar <NUM>, thereby reducing the costs and ensuring the reliability. In addition, the heights of the first pad point <NUM> and the first busbar <NUM> are not required to be too high, so that the paste consumption is reduced. Moreover, since there is no need to print the insulation paste in a large area, the problem of poor adhesion with some paste will not occur, thereby reducing the difficulty of mass production. Compared with the second electrode pattern design in the background art, the first busbar <NUM> is located at the first edge of the back contact cell, and the first pad point <NUM> is away from the first edge of the back contact cell, so as to avoid stress concentration in the welding process, thereby improving the yield of the module and improving the reliability of the module. Compared with the third electrode pattern design in the background art, the photo-generated electrons and holes are not required to cross a long distance to reach the region having the opposite polarity, to collect the currents, thereby fully ensuring relatively high photoelectric conversion efficiency.

Embodiment <NUM> provides a back contact cell module. The back contact cell module comprises the back contact cell described in Embodiment <NUM>.

Embodiment <NUM> provides a back contact cell system. The back contact cell system comprises the back contact cell module described in Embodiment <NUM>.

Claim 1:
An electrode structure of a back contact cell, the back contact cell comprising a first polarity region, a second polarity region, and a first edge, the electrode structure comprising:
a plurality of first fingers (<NUM>), configured to collect the first polarity region;
a plurality of second fingers (<NUM>), configured to collect the second polarity region;
a first busbar (<NUM>), disposed on a side of the back contact cell close to the first edge and connected to the first fingers (<NUM>);
a plurality of first pad points (<NUM>); and
a plurality of first connection electrodes (<NUM>), respectively connected to the first busbar (<NUM>) and the first pad points (<NUM>);
wherein
a distance between each of the first pad points (<NUM>) and the first edge is greater than a distance between the first busbar (<NUM>) and the first edge; and characterized in that:
the second fingers (<NUM>) comprise first bent fingers between the first busbar (<NUM>) and the first pad points (<NUM>), the first bent fingers are respectively bent toward the first busbar (<NUM>) and the first pad points (<NUM>), and are in contact with neither the first busbar (<NUM>) nor the first pad points (<NUM>), or the first bent fingers are bent toward the first busbar (<NUM>) and are not in contact with the first busbar (<NUM>), or the first bent fingers are bent toward the first pad points (<NUM>) and are not in contact with the first pad points (<NUM>).