JP2022006836A - Solar cell string and solar cell module - Google Patents

Abstract

To provide a reliable solar cell string and solar cell module for interconnector connections.SOLUTION: A solar cell string 1 according to an embodiment of the present invention includes a plurality of solar cells 10 arranged in a row in a first direction, and an interconnector 20 connecting between two adjacent solar cells 10, and the solar cell 10 includes a first electrode pattern 14 and a second electrode pattern 15 having different polarities on the back surface, the first electrode pattern 14 includes a plurality of first fixing pad portions 144 to which the interconnector 20 is fixed, and a plurality of contact pad portions 145 with which the interconnector 20 is slidably contacted, and the second electrode pattern 15 includes a plurality of second fixing pad portions 153 to which the interconnector 20 is fixed.SELECTED DRAWING: Figure 1

Description

The present invention relates to solar cell strings and solar cell modules.

A solar cell module having a plurality of solar cells is often formed by using a solar cell string in which a plurality of solar cells are arranged in a row and adjacent solar cells are connected by an interconnector. Solar cells are configured to draw power through an electrode pattern formed on the surface.

In a backside electrode type solar cell in which a pair of electrode patterns having different polarities are both provided on the back surface, a pair of electrode patterns are spread over the entire surface in order to collect current from the entire cell, and a pair is used to prevent a short circuit. It is necessary to arrange the electrode patterns of the above so as not to contact each other. In order to satisfy these conditions, a large number of thin linear electrodes (finger electrodes) with different polarities are arranged alternately, and a slightly wider electrode connecting these linear electrodes for current collection. (Bus bar electrode) and an electrode pattern having.

To improve the efficiency of the solar cell string, the electrical resistance of the electrode pattern as seen from the interconnector, that is, the electrical resistance between the electrode pad (which can be part of the busbar electrode) connected to the interconnector and the end. Is desired to be small. Therefore, it is desirable that the electrode pad also has a pad portion in a region away from the adjacent solar cell in order to reduce the distance between the pad portion and the end.

Usually, the bus bar electrode is made of metal and has a different thermal expansion rate from the main body of a solar cell formed of a silicon substrate or the like. Therefore, there is a possibility that thermal stress acts between the bus bar electrode and the main body of the solar cell due to the temperature change. Patent Document 1 proposes to make the width of the central portion of the bus bar smaller than the width of the end portion in order to alleviate the warp of the solar cell due to the thermal stress between the substrate and the bus bar electrode.

Japanese Unexamined Patent Publication No. 2013-045951

In the solar cell described in Patent Document 1, a bus bar is arranged so as to traverse the solar cell, and a connecting member (interconnector) is connected over the entire length of the bus bar. Generally, since the interconnector is also formed of metal, the interconnector may be separated due to the thermal stress generated by the difference in the thermal expansion rate between the bus bar and the solar cell. Therefore, it is an object of the present invention to provide a solar cell string and a solar cell module with high reliability in connecting an interconnector.

A solar cell string according to an aspect of the present invention comprises a plurality of solar cells arranged in a row in a first direction and an interconnector connecting between two adjacent solar cells, said solar cell. The cell has a first electrode pattern and a second electrode pattern having different polarities on the back surface, and in the first electrode pattern, a plurality of first fixing pad portions to which the interconnector is fixed and the interconnector slide. The second electrode pattern has a plurality of second fixing pad portions to which the interconnector is fixed.

In the solar cell string, the contact pad portion may be arranged at one end of the solar cell in the first direction.

In the solar cell string, the interconnector has a contact wiring portion extending in a second direction intersecting the first direction so as to contact the plurality of contact pad portions, and one side of the contact wiring portion in the first direction. A plurality of first fixed wiring portions each extending to the first fixed pad portion and extending from the contact wiring portion to the other side in the first direction and fixed to the second fixed pad portion, respectively. It may have a plurality of second fixed wiring portions.

In the solar cell string, the solar cell is arranged so that its ends in the first direction overlap each other, and the contact pad portion is arranged on the back side of the adjacent solar cell of the solar cell. It may be disposed at the end on the side.

The solar cell string is laminated on the back surface side of the solar cell, and further includes a plurality of insulating sheets interposed between the solar cell and the interconnector, and the insulating sheet is the first. It may have a plurality of first fixed openings each exposing the fixed pad portion, a plurality of contact openings each exposing the contact pad portion, and a plurality of second fixed openings each exposing the second fixed pad portion. ..

In the solar cell string, the contact opening may be larger than the first fixed opening and the second fixed opening.

The solar cell module according to one aspect of the present invention includes the solar cell string.

According to the present invention, it is possible to provide a solar cell string and a solar cell module with high reliability in connecting an interconnector.

It is a schematic back view of the solar cell string which concerns on one Embodiment of this invention. It is a schematic cross-sectional view of the solar cell string of FIG. It is a schematic back view of the solar cell of the solar cell string of FIG. 1. It is a schematic back view of the interconnector of the solar cell string of FIG. It is a schematic back view of the insulation sheet of the solar cell string of FIG. FIG. 3 is a schematic cross-sectional view of a solar cell module including the solar cell string of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the same reference numerals are given to the same or corresponding parts in each drawing. Further, for the sake of simplification, illustrations, reference numerals, etc. of the members may be omitted, but in such cases, other drawings shall be referred to. Further, the shapes and dimensions of various members in the drawings are adjusted for convenience and to be easily seen.

<Solar cell string>
FIG. 1 is a schematic back view showing a solar cell string 1 according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of the solar cell string 1.

The solar cell string 1 according to an embodiment of the present invention includes a plurality of solar cells 10 arranged in a row in a first direction, an interconnector 20 connecting between two adjacent solar cells 10, and the sun. A plurality of insulating sheets 30 laminated on the back surface side (opposite the light receiving surface) of the battery cell 10 and interposed between the solar cell 10 and the interconnector 20 are provided. The plurality of solar cells 10 are arranged so that the ends in the first direction are overlapped with each other in a certain direction. That is, the solar cell string 1 has a so-called single ring structure.

The solar cell 10 is a so-called heterojunction back contact type solar cell. As shown in detail in FIG. 3, the solar cell 10 includes a semiconductor substrate 11, a first semiconductor layer 12 and a second semiconductor layer 13 formed so as not to substantially overlap the back surface of the semiconductor substrate 11, and a first semiconductor. It has a first electrode pattern 14 laminated on the back surface of the layer 12 and a second electrode pattern 15 laminated on the back surface of the second semiconductor layer 13.

The semiconductor substrate 11 functions as a photoelectric conversion substrate that absorbs incident light from the light receiving surface side to generate optical carriers (electrons and holes). The semiconductor substrate 11 is formed of a crystalline silicon material such as single crystal silicon or polycrystalline silicon. The semiconductor substrate 11 is, for example, an n-type semiconductor substrate in which a crystalline silicon material is doped with an n-type dopant. Examples of the n-type dopant include phosphorus (P). By using crystalline silicon as the material of the semiconductor substrate 11, relatively high output (stable output regardless of illuminance) can be obtained even when the dark current is relatively small and the intensity of the incident light is low.

The first semiconductor layer 12 and the second semiconductor layer 13 attract carriers generated in the semiconductor substrate 11 to collect electric charges. It is preferable that the first semiconductor layer 12 and the second semiconductor layer 13 are arranged so as to cover substantially the entire surface of the semiconductor substrate 11 together.

The first semiconductor layer 12 and the second semiconductor layer 13 have different conductive types from each other. As an example, the first semiconductor layer 12 is formed of a p-type semiconductor, and the second semiconductor layer 13 is formed of an n-type semiconductor. The first semiconductor layer 12 and the second semiconductor layer 13 can be formed of, for example, an amorphous silicon material containing a dopant that imparts a desired conductive type. Examples of the p-type dopant include boron (B), and examples of the n-type dopant include phosphorus (P) described above.

The first semiconductor layer 12 is formed in a band shape extending in a second direction intersecting the first direction, respectively, and is arranged in a matrix in the first direction and the second direction, and the first terminal semiconductor portion 121 and the first. A plurality of first intermediate semiconductor portions 122 extending in the first direction so as to connect a plurality of first terminal semiconductor portions 121 arranged in a direction, and a plurality of semiconductor substrate 11 formed along a side edge on one side in the first direction. It has a base end semiconductor portion 123 for connecting the first intermediate semiconductor portion 122 of the above.

The second semiconductor layer 13 is formed in a band shape extending in the second direction intersecting the first direction, and is arranged in a matrix shape alternately with the first terminal semiconductor portion 121 in the first direction. It has a semiconductor portion 131 and a plurality of second intermediate semiconductor portions 132 extending in the first direction so as to connect the plurality of second terminal semiconductor portions 131 arranged in the first direction. The plurality of second intermediate semiconductor units 132 are not connected to each other.

The first electrode pattern 14 and the second electrode pattern 15 take out electric charges from the first semiconductor layer 12 and the second semiconductor layer 13, respectively, and output electric power from the solar cell 10 to the outside via the interconnector 20 described later. That is, the solar cell 10 has a first electrode pattern 14 and a second electrode pattern 15 having different polarities from each other on the back surface. The first electrode pattern 14 and the second electrode pattern 15 are formed on the outer edges of the first semiconductor layer 12 and the second semiconductor layer 13 at least in a region not arranged on the back side of the other solar cell 10 due to mutual insulation. Each is laminated so as to leave a margin.

The first electrode pattern 14 and the second electrode pattern 15 can be formed by patterning a metal layer such as copper or nickel by etching. Further, the first electrode pattern 14 and the second electrode pattern 15 may be formed by printing and firing a conductive material such as silver paste, and an adherend is a thin layer having conductivity laminated in a desired pattern. It may be formed by plating.

The first electrode pattern 14 includes a plurality of first-terminal current collectors 141 laminated on the first-terminal semiconductor unit 121, and a plurality of first intermediate current collectors 142 laminated on the first intermediate semiconductor unit 122, respectively. , A base end current collector 143 laminated on the base end semiconductor unit 123. The first intermediate current collector 142 is provided with a first fixed pad portion 144 to which the interconnector 20 is fixed, and the proximal current collector 143 is provided with a contact pad portion 145 to which the interconnector 20 is slidably contacted. Is provided. That is, the first electrode pattern 14 is a plurality of contacts arranged at one end of the solar cell 10 in the first direction, more specifically at the end of the side arranged on the back side of the adjacent solar cell 10. It has a pad portion 145 and a plurality of first fixed pad portions 144 arranged on the other side of the contact pad portion 145 in the first direction. The first fixed pad portion 144 and the contact pad portion 145 may be formed so as to protrude from the first intermediate current collector portion 142 and the proximal end current collector portion 143, and the first intermediate current collector portion 142 and the proximal end current collector portion 142 may be formed. It may be a partial area of 143.

The second electrode pattern 15 includes a plurality of second-terminal current collectors 151 laminated on the second-terminal semiconductor section 131, and a plurality of second intermediate current collectors 152 stacked on the second intermediate semiconductor section 132, respectively. , Have. The second intermediate current collector 152 is provided with a second fixed pad portion 153 to which the interconnector 20 is fixed. That is, the second electrode pattern 15 has a plurality of second fixed pad portions 153 arranged on the other side in the first direction from the contact pad portion 145 of the first electrode pattern 14. The second fixed pad portion 153 may be formed so as to protrude from the second intermediate current collector portion 152, or may be a partial region of the second intermediate current collector portion 152.

The interconnector 20 connects the first electrode pattern 14 of the solar cell 10 and the second electrode pattern 15 of the adjacent solar cell 10, respectively. The interconnector 20 may be formed from a metal foil such as copper.

As shown in detail in FIG. 4, the interconnector 20 extends from the contact wiring portion 21 in the second direction so as to come into contact with the plurality of contact pad portions 145, and extends from the contact wiring portion 21 to one side in the first direction, respectively. A plurality of first fixed wiring portions 22 fixed to the first fixed pad portion 144 and a plurality of first fixed wiring portions 22 extending alternately from the contact wiring portion 21 to the other side in the first direction and in the second direction from the first fixed wiring portion 22. Each has a plurality of second fixed wiring portions 23 fixed to the second fixed pad portion 153.

The contact wiring portion 21 is overlapped on the back side of the plurality of contact pad portions 145 and is slidably contacted. The first fixed wiring portion 22 is immovably connected to a plurality of overlapping first fixed pad portions 144 by a connecting material 40 such as solder or a conductive adhesive. The second fixed wiring portion 23 is immovably connected to the plurality of overlapping second fixed pad portions 153 by the connecting material 40. As shown in the figure, the widths of the first fixed wiring portion 22 and the second fixed wiring portion 23 in the second direction may be larger on the contact wiring portion 21 side as long as they do not overlap each other. As a result, the rigidity of the first fixed wiring portion 22 and the second fixed wiring portion 23 is improved, so that the interconnector 20 can be easily handled at the time of manufacturing the solar cell string 1.

The insulating sheet 30 is interposed between the solar cell 10 and the interconnector 20, and the interconnector 20 is a portion other than the first fixed pad portion 144 and the contact pad portion 145 of the first electrode pattern 14, and the second electrode pattern 15. It prevents a short circuit from occurring in contact with a portion other than the second fixed pad portion 153.

As shown in detail in FIG. 5, the insulating sheet 30 has a plurality of first fixed openings 31 that expose the first fixed pad portion 144, a plurality of contact openings 32 that each expose the contact pad portion 145, and a second fixed pad. It has a plurality of second fixed openings 33, each of which exposes a portion. Further, the insulating sheet 30 further has a sealing material opening 34 that opens a region that does not overlap with the interconnector 20.

In addition, in FIG. 2, in order to show the thickness of each component in a large size for easy understanding, it seems that the interconnector 20 is in contact with the contact pad portion 145 by extremely bulging toward the solar cell 10. However, in reality, since the thickness of the insulating sheet 30 is sufficiently small, the interconnector 20 is easily pressed by the encapsulant 4 when the solar cell module is formed as described later. Contact part 145. Further, in order to further facilitate such deformation of the interconnector 20, the contact opening 32 is preferably larger than the first fixed opening 31 and the second fixed opening 33.

<Solar cell module>
FIG. 6 is a schematic cross-sectional view of the solar cell module M according to the embodiment of the present invention. The solar cell module M of FIG. 6 has a plurality of solar cell strings 1, a surface protective material 2 that covers the front surface side of the plurality of solar cell strings 1, a back surface protective material 3 that covers the back surface side of the solar cell string 1, and a front surface thereof. A sealing material 4 that fills the space around the solar cell string 1 between the protective material 2 and the back surface protective material 3 is provided.

In the solar cell module M, a plurality of solar cell strings 1 are arranged side by side in the second direction and parallel to each other.

The surface protective material 2 protects the solar cell 10 by covering the surface of the solar cell string 1, that is, the solar cell 10 via the sealing material 4. The surface protective material 2 can be formed from a plate-shaped or sheet-shaped material, and is preferably excellent in translucency and weather resistance. Specifically, examples of the material of the surface protective material 2 include transparent resins such as acrylic resin and polycarbonate resin, and glass. Further, the surface of the surface protective material 2 may be processed into an uneven shape or coated with an antireflection coating layer in order to suppress the reflection of light.

The back surface protective material 3 protects the solar cell 10 by covering the back surface of the solar cell string 1 via the sealing material 4. Like the surface protective material 2, the back surface protective material 3 can be formed of a plate-shaped or sheet-shaped material, and is preferably excellent in water-shielding property. Specifically, the back surface protective material 3 includes, for example, a resin film such as polyethylene terephthalate (PET), polyethylene (PE), an olefin resin, a fluorine-containing resin, and a silicone resin, and a metal such as such a resin film and an aluminum foil. A laminate with a foil or the like is preferably used.

The sealing material 4 seals and protects the solar cell string 1, that is, the solar cell 10, and particularly prevents moisture from coming into contact with the solar cell 10. The sealing material 4 adheres to the solar cell 10 at the sealing material opening 34 of the insulating sheet 30 to reinforce the connection strength between the solar cells 10 by the interconnector 20.

The sealing material 4 protects the solar cell 10 by adhering the solar cell string 1, the front surface protective material 2 and the back surface protective material 3, and eliminating the gap around the solar cell string 1. Therefore, examples of the sealing material 4 include ethylene / vinyl acetate copolymer (EVA), ethylene / α-olefin copolymer, ethylene / vinyl acetate / triallyl isocyanurate (EVAT), and polyvinyl butyral (PVB). ), Acrylic resin, urethane resin, or a translucent thermoplastic resin such as silicone resin is preferably used.

The solar cell module M is made of a first sheet made of a thermoplastic resin that forms the front side portion of the surface protective material 2, the sealing material 4, and a thermoplastic resin that forms the back side portion of the solar cell string 1 and the sealing material 4. The second sheet and the back surface protective material 3 are laminated in this order, and the laminated body is hot-pressed to melt and integrate the first sheet and the second sheet to form the sealing material 4. Can be manufactured with.

In the solar cell string 1, since the interconnector 20 is slidably contacted with the contact pad portion 145 of the solar cell 10, the thermal expansion amount of the solar cell 10 in which the thermal expansion of the semiconductor substrate 11 is dominant and the inter. It is possible to maintain the electrical connection between the solar cell 10 and the interconnector 20 while absorbing the difference from the thermal expansion amount of the connector 20. Therefore, the solar cell string 1 and the solar cell module M using the solar cell string 1 have high reliability in connecting the interconnector 20.

In the solar cell string 1, since the contact pad portion 145 is arranged on one side in the first direction of the solar cell 10, the length of the portion fixed to one solar cell 10 of the interconnector 20 is the solar cell. It is sufficiently smaller than the length of the cell 10 in the first direction. As a result, the thermal stress due to the difference in the thermal expansion rate between the solar cell 10 and the interconnector 20 can be efficiently relaxed, so that the interconnector 20 is difficult to peel off from the solar cell 10.

In the solar cell string 1, the interconnector 20 is formed in a tree shape in which the first fixed wiring portion 22 and the second fixed wiring portion 23 branch from the contact wiring portion 21, so that the contact wiring portion 21 is the contact pad portion 145. It has a certain area around the part that comes into contact with. Therefore, when the solar cell module M is formed, the sealing material 4 is prevented from accidentally intruding between the contact pad portion 145 and the contact wiring portion 21, so that the connection reliability of the interconnector 20 can be improved. Can be improved further.

Further, in the interconnector 20, the first fixed wiring portion 22 and the second fixed wiring portion 23 extend from the contact wiring portion 21 in the opposite direction to each other in the first direction and alternately in the second direction, whereby each sun. The thermal displacement of the battery cell 10 can be absorbed by the contact wiring portion 21, and the relative position between the solar cell 10 can be maintained to prevent the solar cell 10 from moving in the solar cell module M.

Since the contact pad portion 145 is arranged at the end of the solar cell 10 on the side arranged on the back side of the adjacent solar cell 10, that is, at the portion where the thickness of the solar cell string 1 is relatively large, the contact pad portion 145 is arranged at the inter. The pressure contact force of the connector 20 with respect to the contact pad portion 145 is large, and the contact between the contact pad portion 145 and the interconnector 20 is ensured. Further, by providing the contact pad portion 145 in a portion that does not contribute to photoelectric conversion by being arranged on the back side of the other solar cell 10, the contact pad portion 145 of the first electrode pattern 14 is provided without lowering the photoelectric conversion efficiency. As a result, the contact wiring portion 21 of the base end current collector portion 143 and the interconnector 20 can be enlarged to ensure contact between the contact pad portion 145 and the interconnector 20.

Since the solar cell string 1 has an insulating sheet 30 interposed between the solar cell 10 and the interconnector 20, the first electrode pattern 14 and the second electrode pattern 15 have a relatively simple structure. It is possible to reliably prevent a short circuit due to contact of the interconnector 20 with an unintended portion.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and modifications can be made.

The solar cell string according to the present invention omits an insulating sheet by providing the solar cell with a structure such as a solder resist that prevents the interconnector from coming into contact with an unintended portion of the first electrode putter and the second electrode pattern. It may be.

In the above-mentioned solar cell string, the number and arrangement of the first fixed pad portion, the contact pad portion and the second fixed pad portion can be arbitrarily changed. For example, the first fixed pad portion and the second fixed pad portion may be provided side by side in the first direction. Further, the first fixed pad portion may be provided near the side edge on one side in the first direction of the semiconductor substrate, and the contact pad portion may be provided on the other side in the first direction with respect to the first fixed pad portion.

In the solar cell string according to the present invention, the shapes of the first semiconductor layer, the second semiconductor layer, the first electrode pattern, and the second electrode pattern are not limited to the shapes of the above-described embodiments. As an example, the second electrode pattern may also have a second base end current collector for connecting a plurality of second intermediate current collectors, similarly to the first electrode pattern.

In the solar cell string according to the present invention, the thickness of the first electrode pattern and the second electrode pattern is set to the thickness of the first fixed pad portion, the contact pad portion and the second fixed pad portion in order to facilitate the connection of the interconnector. It may be locally enlarged in at least a part of the area.

Further, in the solar cell string according to the present invention, two adjacent solar cells may be connected by a plurality of interconnectors.

1 Solar cell string 2 Front surface protective material 3 Back surface protective material 4 Encapsulant 10 Solar cell cell 11 Semiconductor substrate 12 1st semiconductor layer 121 1st terminal semiconductor part 122 1st intermediate semiconductor part 123 Base end semiconductor part 13 2nd semiconductor layer 131 2nd terminal semiconductor part 132 2nd intermediate semiconductor part 14 1st electrode pattern 141 1st terminal current collecting part 142 1st intermediate current collecting part 143 base end current collecting part 144 1st fixed pad part 145 contact pad part 15 2nd Electrode pattern 151 2nd terminal current collector 152 2nd intermediate current collector 153 2nd fixed pad 20 Interconnector 21 Contact wiring 22 1st fixed wiring 23 2nd fixed wiring 30 Insulation sheet 31 1st fixed opening 32 Contact opening 33 Second fixed opening 34 Encapsulant opening 40 Connection material M Solar cell module

Claims (7)

Multiple solar cells arranged in a row in the first direction,
An interconnector that connects between two adjacent solar cells,
Equipped with
The solar cell has a first electrode pattern and a second electrode pattern having different polarities on the back surface thereof.
The first electrode pattern has a plurality of first fixing pad portions to which the interconnector is fixed, and a plurality of contact pad portions to which the interconnector is slidably contacted.
The second electrode pattern is a solar cell string having a plurality of second fixing pad portions to which the interconnector is fixed. The solar cell string according to claim 1, wherein the contact pad portion is disposed at one end of the solar cell in the first direction. The interconnector is
A contact wiring portion extending in a second direction intersecting with the first direction so as to come into contact with the plurality of contact pad portions.
A plurality of first fixed wiring portions extending from the contact wiring portion to one side in the first direction and fixed to the first fixed pad portions, respectively.
A plurality of second fixed wiring portions extending from the contact wiring portion to the other side in the first direction and fixed to the second fixed pad portion, respectively.
The solar cell string according to claim 2. The solar cells are arranged so that their ends in the first direction overlap each other.
The solar cell string according to claim 2 or 3, wherein the contact pad portion is arranged at an end portion of the solar cell adjacent to the solar cell on the side arranged on the back side of the solar cell. A plurality of insulating sheets laminated on the back surface side of the solar cell and interposed between the solar cell and the interconnector are further provided.
The insulating sheet has a plurality of first fixed openings that expose the first fixed pad portion, a plurality of contact openings that each expose the contact pad portion, and a plurality of second openings that each expose the second fixed pad portion. The solar cell string according to any one of claims 1 to 4, which has a fixed opening.
The solar cell string according to claim 5, wherein the contact opening is larger than the first fixed opening and the second fixed opening. A solar cell module comprising the solar cell string according to any one of claims 1 to 6.

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