TWI514593B - Solar cell and module comprising the same - Google Patents

Description

Solar cell and its module

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

Referring to FIG. 1 , a known interdigitated back contact (IBC) solar cell generally includes a substrate 91 and an emitter region 92 respectively located at a back surface 911 of the substrate 91. And a back surface doped region 93, a passivation layer 94 on the back surface 911, a front surface doped region 97 located in a light receiving surface 912 of the substrate 91, and an anti-reflection layer on the light receiving surface 912 The reflective layer 98, a first electrode 95 electrically connected to the emitter region 92, and a second electrode 96 electrically connected to the back surface doping region 93.

The yoke-type back contact solar cell is characterized in that the first electrode 95 and the second electrode 96 are located on the back surface 911 side of the substrate 91. The light-receiving surface 912 of the substrate 91 is not provided with an electrode and is not blocked, so that it can be lifted. The amount of light incident on the light receiving surface 912. In use, the carrier generated by the photoelectric effect of the substrate 91 needs to be transferred to the emitter region 92 or the back surface doped region 93, and then exported through the first electrode 95 and the second electrode 96. For use.

However, in the diffusion process performed in the fabrication of the emitter region 92 or the front surface doping region 97, a portion of the substrate 91 connecting the light receiving surface 912 and the side surface 913 of the back surface 911 may remain mixed. The impurity impurities not only easily cause the carriers to recombine but also generate leakage current, resulting in a decrease in the photoelectric conversion efficiency of the solar cell. Therefore, how to reduce the probability of carrier recombination, how to reduce the occurrence of leakage current, and how to increase the efficiency of collecting the carrier of the emitter region 92 and the back surface doping region 93 to improve the photoelectric conversion efficiency of the solar cell is An important topic.

Accordingly, it is an object of the present invention to provide a solar cell and a module thereof which can reduce the probability of leakage current and carrier recombination and can improve the efficiency of collecting carriers to improve photoelectric conversion efficiency.

Thus, the solar cell of the present invention comprises: a substrate, a passivation layer, and an electrode unit.

The substrate includes an opposite light receiving surface and a back surface, and an emitter region, a back surface electric field region and a spacer region disposed on the back surface side. The back has a surrounding side edge. The spacer has an inner spacer separating the emitter region from the back surface electric field region, and an outer surrounding portion disposed adjacent to the peripheral side and surrounding. One of the emitter region and the back surface electric field region has an annular doped portion that abuts the outer surrounding portion and is circumferentially disposed. The passivation layer is on the back side. The electrode unit is located on the passivation layer and passes through the passivation layer to connect the emitter region and the back surface electric field region.

The solar cell module of the present invention comprises: a first plate and a second plate disposed opposite to each other, and a plurality of the first plate and the first plate a solar cell between the second plate and a package between the first plate and the second plate and wrapped around the plurality of solar cells.

The effect of the invention is that the innovative structural design of the spacer can effectively reduce the occurrence of leakage current in the substrate and reduce the probability of carrier recombination, thereby improving the photoelectric conversion efficiency of the solar cell. More importantly, when one of the emitter region and the back surface electric field region has the annular doping portion, the efficiency of collecting carriers can be enhanced through the annular doping portion, thereby further improving the solar cell. Photoelectric conversion efficiency.

11‧‧‧ first plate

12‧‧‧Second plate

13‧‧‧Solar battery

14‧‧‧Package

15‧‧‧welding wire

2‧‧‧Substrate

21‧‧‧Stained surface

22‧‧‧ Back

221‧‧‧around sides

23‧‧‧ side

24‧‧‧ front surface electric field

25‧‧‧The polar zone

251‧‧‧Circular doping

252‧‧‧ base section

253‧‧‧First week

254‧‧‧second week

255‧‧‧First Extension

256‧‧‧ Collection Department

26‧‧‧Back surface electric field

261‧‧‧ Collection Department

262‧‧‧Second extension

263‧‧‧Circular doping

264‧‧‧ base section

265‧‧‧First week

266‧‧‧Second week

27‧‧‧ interval zone

271‧‧‧Interval

272‧‧‧Outer Surroundings

31‧‧‧Anti-reflective layer

32‧‧‧ Passivation layer

4‧‧‧Electrode unit

40‧‧‧ ring electrode

401‧‧‧ base electrode

402‧‧‧First week electrode

403‧‧‧second week electrode

41‧‧‧First electrode

411‧‧‧First finger electrode

412‧‧‧Concurrent electrode

42‧‧‧second electrode

421‧‧‧Concurrent electrode

422‧‧‧second finger electrode

81‧‧‧First direction

82‧‧‧second direction

D1, d2‧‧‧ distance

Width t1~t4‧‧‧

Other features and effects of the present invention will be apparent from the following description of the drawings, wherein: FIG. 1 is a schematic cross-sectional view of a general interdigitated back contact solar cell; FIG. 2 is a solar cell module of the present invention. A schematic cross-sectional view of a first preferred embodiment; FIG. 3 is a rear view showing the solar cell of the first preferred embodiment; FIG. 4 is a cross-sectional view taken along line AA of FIG. FIG. 5 is a rear view showing a substrate of the solar cell separately; FIG. 6 is a rear view showing the solar cell module of the present invention. 2 is a solar cell of a preferred embodiment; FIG. 7 is a cross-sectional view taken along line BB of FIG. 6, and FIG. 7 is The back side of the solar cell is drawn downward; and FIG. 8 is a schematic rear view showing one of the substrates of the solar cell.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same reference numerals.

Referring to FIG. 2, a first preferred embodiment of the solar cell module of the present invention comprises: a first plate 11 and a second plate 12 disposed at an upper and lower interval, and a plurality of arrays arranged on the first plate 11 and The solar cell 13 between the second sheets 12 and a package 14 between the first sheet 11 and the second sheet 12 and surrounding the plurality of solar cells 13. Of course, in practice, the solar cell module may include only one solar cell 13.

In the present embodiment, the material of the first plate 11 and the second plate 12 is not particularly limited, and a glass or plastic plate may be used, and the plate on the light receiving side of the solar cell 13 must be transparent. The material of the encapsulant 14 is, for example, a light transmissive ethylene vinyl acetate copolymer (EVA), or other related materials usable for the solar cell module package, and is not limited to the examples of the embodiment. Further, the plurality of solar cells 13 are electrically connected to each other through a plurality of ribbon wires 15. Since the structures of the plurality of solar cells 13 are the same, only one of them will be described below as an example. Of course, the structure of the plurality of solar cells 13 in a module is not absolutely necessary.

Referring to Figures 3, 4, 5, the solar cell 13 package of the present embodiment A substrate 2, an anti-reflection layer 31, a passivation layer 32, and an electrode unit 4 are included.

The substrate 2 of the present embodiment is an n-type single crystal germanium substrate or a polycrystalline germanium substrate, and includes a light receiving surface 21 and a back surface 22 opposite to each other, and a connecting surface between the light receiving surface 21 and the back surface 22 and surrounded by four sides. The side surface 23, a front surface electric field region 24 disposed on the light receiving surface 21 side, and an emitter region 25 disposed on the back surface 22 side, a back surface electric field region 26 and a spacer region 27.

The light-receiving surface 21 has a roughened structure, thereby increasing the amount of light incident; and the back surface 22 has a peripheral side 221 that surrounds and connects the side surface 23.

The front surface electric field region 24 is located inside the light receiving surface 21, and is disposed to extend along the unevenness of the light receiving surface 21. The front surface electric field region 24 is an n ⁺ -type semiconductor, and its doping concentration is greater than the doping concentration of the substrate 2, thereby forming a front-surface electric field (Front-Side Field, FSF for short) to improve carrier collection efficiency and photoelectric conversion. effectiveness. In practice, a diffusion process (eg, phosphorus diffusion) or other doping method may be utilized to make the doping concentration at the light receiving surface 21 higher than the inside of the substrate 2, thereby forming an n ⁺ -type semiconductor.

The emitter region 25 is located within the back surface 22 and is a p ⁺ -type semiconductor having a different doping property than the substrate 2, thereby forming a pn junction, which is a source of photoelectric effect. The emitter region 25 has an annular doping portion 251 surrounded by a square ring and spaced apart from the surrounding side edge 221, and a plurality of first ring-shaped doping portions 251 connected by the annular doping portion 251 Extension 255. In FIG. 5, an imaginary line is marked on the emitter region 25 for ease of understanding, thereby distinguishing the annular doping portion 251 from the plurality of first extending portions 255.

The annular doping portion 251 has a base portion 252 extending along a first direction 81, a first circumferential portion 253 spaced apart from the base portion 252 in a second direction 82 and extending along the first direction 81, and two A second circumferential section 254 extending between the base section 252 and the first circumferential section 253 is spaced apart from each other along the second direction 82. The plurality of first extensions 255 extend from the base section 252 along the first direction 81 toward the first circumferential section 253, respectively. In practice, the emitter region 25 partially forms a heavily doped p ⁺ -type semiconductor inside the substrate 2 by a diffusion process (eg, boron diffusion) or other doping. Further, in the present embodiment, the first direction 81 is perpendicular to the second direction 82, but in practice, the angle relationship between the two is not particularly limited.

The back surface electric field region 26 is located within the back surface 22 and is an n ⁺⁺ type semiconductor. The back surface electric field region 26 is circumferentially surrounded by the annular doping portion 251 and has a collecting portion 261 adjacent to the first circumferential portion 253 and extending along the first direction 81, and a plurality of collecting portions 261 A second extension 262 extends along the second direction 82 toward the base segment 252. The plurality of first extending portions 255 and the plurality of second extending portions 262 are staggered in the first direction 81, and the width t1 of the plurality of first extending portions 255 is greater than the width t2 of the plurality of second extending portions 262. . In practice, the back surface electric field region 26 is partially formed into a heavily doped n ⁺⁺ type semiconductor by a diffusion process (eg, phosphorus diffusion) or other doping manner, and the doping concentration thereof is greater than The doping concentration of the substrate 2, thereby forming a Back-Side Field (BSF) to improve carrier collection efficiency and photoelectric conversion efficiency.

It should be noted that if the substrate 2 is a p-type semiconductor substrate, the front surface electric field region 24 is formed as a p ⁺ -type semiconductor having a doping concentration greater than that of the p-type substrate 2, and the back surface electric field region 26 is fabricated. The p ⁺⁺ type semiconductor having a doping concentration greater than that of the front surface electric field region 24 is formed, and the emitter region 25 is formed as an n-type semiconductor.

The spacer 27 is located within the back surface 22 and has an inner spacer 271 between the emitter region 25 and the back surface electric field region 26, and a peripheral ring 221 adjacent to the surrounding side 221 and surrounded by a square ring And an outer surrounding portion 272 surrounding the emitter region 25 and the back surface electric field region 26. The outer surrounding portion 272 spaces the annular doping portion 251 of the emitter region 25 from the peripheral side edge 221 so that the two are not connected to each other. The inner spacer 271 spaces the emitter region 25 from the back surface electric field region 26 so that the two are not connected to each other.

In fact, when the emitter region 25 and the back surface electric field region 26 are formed by a diffusion process, the emitter region 25 can be separated from the back surface electric field region 26 by appropriate process control, and the emitter region 25 is The region between the back surface electric field regions 26 where no diffusion process is additionally performed becomes the inner spacer portion 271. The surface of the spacer 27 may be unequal to the surface of the emitter region 25 and the back surface electric field region 26 as shown in FIG. 4, but the surface of the spacer region 27 may also be different from the surface. The surface of the polar region 25 and the back surface electric field region 26 are equal in height.

The anti-reflection layer 31 of the present embodiment extends along the uneven surface of the light-receiving surface 21 and is disposed on the light-receiving surface 21 and covers the front surface electric field region 24, such as tantalum nitride (SiN _x ). It is used to increase the amount of light incident and reduce the surface recombination Velocity (SRV).

The passivation layer 32 of the present embodiment is disposed on the back surface 22 and covers the emitter region 25, the back surface electric field region 26 and the spacer region 27. The material of the passivation layer 32 may be an oxide, a nitride or a combination of the above materials, and used to passivate and repair the surface of the substrate 2 to reduce the surface dangling bond and defects, thereby reducing carrier traps (Trap) And reducing the surface recombination rate of the carrier to improve the photoelectric conversion efficiency of the solar cell 13.

The electrode unit 4 of the present embodiment is located on the passivation layer 32 and passes through the passivation layer 32 to connect the emitter region 25 and the back surface electric field region 26.

The electrode unit 4 includes a ring electrode 40 corresponding to the annular doping portion 251, a first electrode 41 connecting the plurality of first extending portions 255, and a second electrode 42 connecting the back surface electric field region 26. In FIG. 3, an imaginary line is marked on the electrode unit 4 for ease of understanding, thereby distinguishing the ring electrode 40 from the first electrode 41.

The outer contour shape of the ring electrode 40 corresponds to the outer contour shape of the annular doping portion 251, which in this example is a square ring shape. The distance d1 between the ring electrode 40 and the peripheral side 221 is greater than the distance d2 between the annular doping portion 251 and the surrounding side 221 . The ring electrode 40 has a base electrode 401 extending along the first direction 81, a first peripheral electrode spaced apart from the base electrode 401 in the second direction 82 and extending along the first direction 81. 402, and two second peripheral electrodes 403 extending along the second direction 82 and spaced apart from each other between the base electrode 401 and the first peripheral electrode 402. The base electrode 401 is correspondingly connected to the base segment 252 of the annular doping portion 251. The first peripheral electrode 402 is correspondingly connected to the first circumferential segment 253 of the annular doping portion 251, and the two second circumferential electrodes 403 are respectively The two second circumferential segments 254 of the annular doped portion 251 are correspondingly connected.

The first electrode 41 has a plurality of first finger electrodes 411 extending from the base electrode 401 along the second direction 82 toward the first peripheral electrode 402. The plurality of first finger electrodes 411 are respectively connected to the shot. The first extension 255 of the pole region 25.

The second electrode 42 is spaced apart from the first electrode 41. The second electrode 42 has a corresponding bus electrode 421 extending away from the base electrode 401 along the first direction 81, and a plurality of the bus electrodes. A second finger electrode 422 extending toward the base electrode 401 in the second direction 82. The plurality of first finger electrodes 411 and the plurality of second finger electrodes 422 are staggered in the first direction 81, respectively. The bus electrode 421 is correspondingly connected to the collecting portion 261 of the back surface electric field region 26, and the plurality of second finger electrodes 422 are respectively connected to the second extending portion 262 of the back surface electric field region 26.

In this embodiment, the emitter region 25 is spaced apart from the back surface electric field region 26 through the inner spacer portion 271 of the spacer 27 to avoid leakage current generated by parasitic shunting (Leakage). Current) and can reduce the probability of carrier recombination. At the same time, the embodiment also passes the emitter region 25 through the outer surrounding portion 272 of the spacer 27. The annular doping portion 251 is spaced apart from the peripheral side 221, so that the inner portion of the substrate 2 adjacent to the side surface 23 is prevented from remaining doped impurities due to the diffusion process of the emitter region 25 or the front surface electric field region 24. The problem of leakage current between the emitter region 25 and the front surface electric field region 24 due to parasitic shunting can be avoided, and the probability of carrier recombination can be reduced.

It is to be noted that the distance d1 between the ring electrode 40 and the surrounding side 221 is greater than the distance d2 between the annular doping portion 251 and the surrounding side 221. The foregoing design makes the ring electrode 40 and the surrounding side 221 Interphase spaces are left with gaps, so that space can be reserved for fixture clamping, and the problem of short circuit caused by contact of adjacent tandem solar cell metal electrodes can be avoided when packaging the solar cell module.

In addition, since the substrate 2 of the present embodiment is an n-type substrate, the electrons are majority carriers and the holes are minority carriers, and the emitter region 25 is for collecting minority carriers, and the back surface electric field region 26 is used. For collecting most carriers. In this embodiment, the width t1 of the plurality of first extending portions 255 is greater than the width t2 of the plurality of second extending portions 262, such that the distribution area of the emitter regions 25 is larger than the distribution area of the back surface electric field regions 26. Therefore, a small number of carriers can transmit the short path length (Travelling Length) to enter the emitter region 25, thereby reducing the carrier recombination rate, improving the collection efficiency of the minority carriers, and thereby improving the photoelectric conversion efficiency of the solar cell 13. The first finger electrode 411 of the first electrode 41 is used to connect the plurality of first extensions 255, and the second finger electrodes 422 of the second electrode 42 are used to connect the plurality of second extensions 262. Correspondingly, the width t3 of the plurality of first finger electrodes 411 is greater than the width t4 of the plurality of second finger electrodes 422. This also enhances the collection efficiency of minority carriers.

Further, the emitter region 25 of the present embodiment further adds an annular doping portion 251 adjacent to the outer surrounding portion 272 of the spacer region 27, and is collected through the annular doping portion 251 to be located inside the substrate 2 adjacent to the surrounding side edge 221 The minority carriers generated in the region can further improve the collection efficiency of the minority carriers, thereby improving the photoelectric conversion efficiency of the solar cell 13. Correspondingly, the electrode unit 4 of the present embodiment further adds a ring electrode 40 surrounding the peripheral side 221 of the substrate 2, and the ring electrode 40 is used to connect the annular doping portion 251 of the emitter region 25 to assist in The minority carriers collected by the annular doping 251 are outwardly led out.

Referring to Figures 6, 7, and 8, a second preferred embodiment of the solar cell module of the present invention is substantially the same as the first preferred embodiment, and the difference between the two is that the emitter region 25 of the substrate 2 The topography of the electric field region 26 with the back surface, and the topography of the electrode unit 4.

The emitter region 25 of the present embodiment is circumferentially surrounded by the back surface electric field region 26, and the emitter region 25 has a collecting portion 256 extending along the first direction 81, and a plurality of collecting portions 256 along the collecting portion The first direction 255 extends in the second direction 82.

The back surface electric field region 26 of the present embodiment has an annular doping portion 263 adjacent to the outer surrounding portion 272 and spaced around the emitter region 25, and a plurality of connecting the annular doping portion 263 and receiving the annular doping portion 263 circled second extension 262. The annular doping portion 263 has a first circumferential section 265 adjacent to the collecting portion 256 and extending along the first direction 81, and a first circumferential direction 265 along the second direction 82 and along the first direction 81 extend The base section 264, and two second circumferential sections 266 extending along the second direction 82 and spaced apart from each other between the base section 264 and the first circumferential section 265.

The second extension portion 262 of the back surface electric field region 26 extends from the base portion 264 along the second direction 82 toward the first circumferential portion 265. The plurality of first extension portions 255 and the plurality of second extension portions 262 respectively Staggered along the first direction 81. The width t1 of the plurality of first extending portions 255 is greater than the width t2 of the plurality of second extending portions 262, so that the distribution area of the emitter regions 25 is larger than the distribution area of the back surface electric field regions 26, thereby promoting minority carriers. Collection efficiency.

The electrode unit 4 of the present embodiment includes a ring electrode 40 corresponding to the annular doping portion 263, a first electrode 41 connected to the emitter region 25, and a second electrode connecting the plurality of second extending portions 262. 42.

The outer contour shape of the ring electrode 40 corresponds to the outer contour shape of the annular doping portion 263. The distance d1 between the ring electrode 40 and the peripheral side 221 is greater than the distance d2 between the annular doping portion 263 and the surrounding side edge 221. The foregoing design can reserve a space for the fixture to be clamped while packaging the solar cell module. The problem of short circuit caused by the contact of adjacent tandem solar cell metal electrodes can be avoided.

The ring electrode 40 has a base electrode 401 extending along the first direction 81, a first peripheral electrode 402 spaced apart from the base electrode 401 in the second direction 82 and extending along the first direction 81, and two edges The second direction 82 extends to be spaced apart from each other and is connected to the second peripheral electrode 403 between the base electrode 401 and the first peripheral electrode 402. The base electrode 401 is correspondingly connected to the base segment 264 of the annular doping portion 263, and the first peripheral electrode 402 is correspondingly connected The first circumferential segment 265 of the annular doping portion 263 is connected, and the two second circumferential electrodes 403 are respectively connected to the two second circumferential segments 266 of the annular doping portion 263.

The first electrode 41 has a bus electrode 412 corresponding to and extending away from the base electrode 401 along the first direction 81, and a plurality of first electrodes extending from the bus electrode 412 along the second direction 82 toward the base electrode 401. Finger electrode 411. The bus electrode 412 is correspondingly connected to the collecting portion 256 of the emitter region 25, and the plurality of first finger electrodes 411 are respectively connected to the first extending portion 255 of the emitter region 25.

The second electrode 42 has a plurality of second finger electrodes 422 extending from the base electrode 401 along the second direction 82 toward the bus electrode 412. The plurality of second finger electrodes 422 respectively connect the back surface electric field. The second extension 262 of the region 26. The plurality of first finger electrodes 411 and the plurality of second finger electrodes 422 are staggered in the first direction 81, respectively.

In this embodiment, the emitter region 25 is spaced apart from the back surface electric field region 26 through the inner spacer 271 of the spacer 27 to avoid leakage current and reduce the probability of carrier recombination. . At the same time, the annular doping portion 263 of the back surface electric field region 26 is spaced from the peripheral side 221 through the outer surrounding portion 272 of the spacer 27, so that the inner portion of the substrate 2 adjacent to the side surface 23 can be avoided. The diffusion process of the back surface electric field region 26 or the front surface electric field region 24 leaves dopant impurities.

It should be noted that the back surface electric field region 26 of the present embodiment further adds the annular doping portion 263 to collect the majority carriers generated in the region of the substrate 2 adjacent to the surrounding side edges 221, thereby improving the majority. The efficiency of collection of carriers. Correspondingly, the electrode unit 4 of the present embodiment further adds a ring electrode 40 surrounding the peripheral side 221 of the substrate 2 to assist in guiding the majority of the carriers outward.

In summary, the innovative structural design of the spacer of the present invention can effectively reduce the chance of leakage current in the substrate and reduce the probability of carrier recombination, thereby improving the photoelectric conversion efficiency of the solar cell. In addition, the design of the width of the plurality of first extensions is greater than the width of the plurality of second extensions, thereby improving the efficiency of collecting a minority carrier, and more importantly, the emitter region and the back surface electric field region. When one of the annular doping portions has the annular doping portion, the efficiency of collecting the carrier can be enhanced through the annular doping portion, so that the photoelectric conversion efficiency of the solar cell can be further improved.

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

13‧‧‧Solar battery

2‧‧‧Substrate

21‧‧‧Stained surface

22‧‧‧ Back

221‧‧‧around sides

23‧‧‧ side

24‧‧‧ front surface electric field

25‧‧‧The polar zone

251‧‧‧Circular doping

254‧‧‧second week

255‧‧‧First Extension

26‧‧‧Back surface electric field

262‧‧‧Second extension

27‧‧‧ interval zone

271‧‧‧Interval

272‧‧‧Outer Surroundings

31‧‧‧Anti-reflective layer

32‧‧‧ Passivation layer

4‧‧‧Electrode unit

40‧‧‧ ring electrode

403‧‧‧second week electrode

41‧‧‧First electrode

411‧‧‧First finger electrode

42‧‧‧second electrode

422‧‧‧second finger electrode

D1, d2‧‧‧ distance

Claims (14)

A solar cell comprising: a substrate comprising an opposite light receiving surface and a back surface; and an emitter region disposed on the back side, a back surface electric field region and a spacer region; the back surface having a surrounding surrounding side The spacer has an inner spacer separating the emitter region from the back surface electric field, and an outer surrounding portion adjacent to the surrounding side and surrounding; the emitter region and the back surface electric field region One of the two has a ring-shaped doping portion adjacent to the outer surrounding portion and surrounding; a passivation layer is disposed on the back surface; and an electrode unit is disposed on the passivation layer and passes through the passivation layer to connect the emitter The area and the back surface electric field region. The solar cell of claim 1, wherein the electrode unit comprises a ring electrode positioned to correspond to the annular doping. The solar cell of claim 2, wherein the distance between the ring electrode and the peripheral side is greater than the distance between the annular doped portion and the surrounding side. The solar cell of claim 2, wherein the emitter region has the annular doping portion; the back surface electric field region is surrounded by the annular doping portion. The solar cell of claim 4, wherein the annular doped portion has a base segment, a first circumferential segment spaced from the base segment, and two are coupled between the base segment and the first circumferential segment a second weekly segment; the emitter region further having a plurality of first extensions extending from the base segment toward the first segment The back surface electric field region has a collecting portion adjacent to the first circumferential portion, and a plurality of second extending portions extending from the collecting portion toward the base portion and staggered with the plurality of first extending portions. The solar cell of claim 5, wherein the electrode unit further comprises a first electrode connecting the plurality of first extensions, and a second electrode connecting the electric field of the back surface; the ring electrode is connected to the ring Doped part. The solar cell of claim 6, wherein the ring electrode has a base electrode correspondingly connected to the base portion of the annular doped portion, a first peripheral electrode spaced from the base electrode, and two connected thereto a second peripheral electrode between the base electrode and the first peripheral electrode; the first electrode has a plurality of first finger electrodes extending from the base electrode toward the first peripheral electrode; the second electrode has a corresponding and distant a bus electrode of the base electrode, and a plurality of second finger electrodes extending from the bus electrode toward the base electrode and staggered with the plurality of first finger electrodes. The solar cell of claim 4, wherein the substrate further comprises a front surface electric field region disposed on the light receiving surface side. The solar cell of claim 2, wherein the back surface electric field region has the annular doping portion; the emitter region is surrounded by the annular doping portion. The solar cell of claim 9, wherein the annular doping portion has a base segment, a first circumferential segment spaced from the base segment, and two are coupled between the base segment and the first circumferential segment a second week; the emitter region has a collection portion adjacent to the first segment, and a plurality of collections a first extension extending toward the base segment; the back surface electric field region further having a plurality of second extensions extending from the base segment toward the first circumferential segment and staggered with the plurality of first extensions. The solar cell of claim 10, wherein the electrode unit further comprises a first electrode connected to the emitter region, and a second electrode connecting the plurality of second extensions; the ring electrode is connected to the ring-shaped electrode Miscellaneous. The solar cell of claim 11, wherein the ring electrode has a base electrode correspondingly connected to the base portion of the annular doping portion, a first peripheral electrode spaced from the base electrode, and two connected thereto a second peripheral electrode between the base electrode and the first peripheral electrode; the first electrode has a bus electrode corresponding to and away from the base electrode, and a plurality of first finger electrodes extending from the bus electrode toward the base electrode The second electrode has a plurality of second finger electrodes extending from the base electrode toward the bus electrode and staggered with the plurality of first finger electrodes. The solar cell of claim 5, 6, 7, 10, 11 or 12, wherein the width of the plurality of first extensions is greater than the width of the plurality of second extensions. A solar cell module comprising: a first plate and a second plate disposed oppositely; and a plurality of solar cells according to any one of claims 1 to 12, arranged on the first plate and the second plate And a package material between the first plate and the second plate and wrapped around the plurality of solar cells.