Solar cell, cell string, photovoltaic module and photovoltaic system

Abstract

The invention is applicable to the field of photovoltaic technology, and provides a solar cell, a cell string, a photovoltaic module and a photovoltaic system, the solar cell comprises a silicon substrate, the silicon substrate is provided with a first region and a second region, the first region is provided with a first doping layer, the second region is provided with a second doping layer, the first region and the second region extend along a first direction, and the second region extends along a second direction. The first doping layer and the second doping layer are arranged in the second direction, the first thin grid lines are arranged on the first doping layer, the second thin grid lines are arranged on the second doping layer, the isolation area is arranged between the first area and the second area, the first doping layer comprises a first body part and a plurality of first extension parts, and the first extension parts protrude from the first body part in the direction towards the isolation area. Since the first doped layer is provided with the protruding first extension part, the current transmission path of the isolation region is increased, the influence of the isolation region on current transmission is reduced, the transmission resistance of electrons or holes to a collection region is reduced, and the photoelectric conversion efficiency of the solar cell is improved.

Description

Technical Field

[0001] This invention belongs to the field of photovoltaic technology, and particularly relates to solar cells, cell strings, photovoltaic modules and photovoltaic systems. Background Technology

[0002] The principle of photovoltaic (PV) cell power generation is to convert light energy into electrical energy through the photovoltaic effect. In practical applications, PV cells can generate electricity not only from light incident on their front side, but also from light reflected from the ground and diffusely reflected from the air on their back side. An important indicator for measuring the power generation performance of the back side of a PV cell is the bifaciality, which is the ratio of the back-side incident light conversion efficiency to the front-side incident light conversion efficiency. Improving the bifaciality is one of the important directions for the development of PV cell technology.

[0003] However, existing technologies present two main problems with the doped regions on the back of photovoltaic cells: First, the doped regions exhibit high parasitic absorption of light, meaning the absorbed light energy cannot be further converted into electrical energy, resulting in wasted light energy; second, to balance surface passivation and metal contact area passivation, the doped regions typically need to be polished, leading to high light reflectivity in these regions. These two factors severely impact the optical performance of the back of photovoltaic cells.

[0004] To improve back-side optical performance, existing technologies typically incorporate trench regions on the back of the battery. However, this solution introduces new problems: the presence of trench regions increases the lateral transport resistance of charge carriers within the silicon substrate, leading to a decrease in conversion efficiency. This negative effect limits the potential for increasing the trench area ratio, thereby restricting the improvement of bifaciality.

[0005] In existing solar cell designs, the doped regions below the fine grid line typically employ a long, narrow strip structure with consistent trench width between adjacent doped regions. This design restricts current flow in the trench region to the lateral doped layers, resulting in suboptimal lateral transport resistance. This structural design severely limits the performance of the cell string, particularly in current harvesting and carrier transport efficiency, significantly hindering improvements in photoelectric conversion efficiency and bifaciality. Summary of the Invention

[0006] The solar cell provided in this invention aims to solve the technical problem that the trench width of existing solar cells affects current collection and transmission, thereby affecting the working efficiency and bifaciality improvement of solar cells.

[0007] The present invention is implemented as follows: a solar cell includes: silicon substrate; The silicon substrate has a first region and a second region. The first region has a first doped layer and the second region has a second doped layer. The first region and the second region extend along a first direction and are arranged along a second direction. A first fine gate line located in the first region, the first fine gate line being disposed on the first doped layer; The second fine gate line is located in the second region and is disposed on the second doped layer.

[0008] An isolation zone is established between the first region and the second region; The first doped layer includes a first body portion and a plurality of first extension portions, wherein the first extension portions protrude from the first body portion in a direction toward the isolation region.

[0009] Furthermore, the second doped layer includes a second body portion and a plurality of second extension portions, the second extension portions protruding in a direction toward the isolation region.

[0010] Furthermore, a plurality of the first extensions are arranged at intervals along the first direction, and the distance between two adjacent first extensions is less than or equal to 1 mm.

[0011] Furthermore, a plurality of the second extensions are arranged at intervals along the first direction, and the distance between two adjacent second extensions is less than or equal to 1 mm.

[0012] Furthermore, along the first direction, the ratio of the sum of the lengths of the plurality of the first extensions to the total length of the first doped layer is greater than or equal to 0.3.

[0013] Furthermore, along the second direction, the ratio of the length of the first extension to the length of the first body portion is greater than or equal to 1.5.

[0014] Furthermore, along the first direction, the ratio of the sum of the lengths of the plurality of second extensions to the total length of the second doped layer is greater than or equal to 0.3.

[0015] Furthermore, along the second direction, the ratio of the length of the second extension to the length of the second body portion is greater than or equal to 1.5.

[0016] Furthermore, along the first direction, the first extension and the second extension are staggered; and / or The first extension and the second extension are aligned and at least partially connected to each other; and / or The first extension and the second extension are aligned and spaced apart.

[0017] Furthermore, the first fine grid line includes a third body portion and a third extension portion, the third extension portion protruding from the third body portion toward the second fine grid line, at least covering a portion of the first extension portion; and / or The second fine grid line includes a fourth body portion and a fourth extension portion, the fourth extension portion protruding from the fourth body portion toward the first fine grid line, at least covering a portion of the second extension portion.

[0018] Furthermore, along the first direction, the third extension and the fourth extension are staggered; and / or The third extension and the fourth extension are aligned, and at least a portion of the third extension and the fourth extension are interconnected; and / or The third extension and the fourth extension are aligned and spaced apart.

[0019] Furthermore, both the first region and the second region are located on the back side of the silicon substrate, and the first region and the second region are at least partially isolated by the isolation region.

[0020] Furthermore, the first region and the second region are both located on the back side of the silicon substrate, or the first region and the second region are located on the front side of the silicon substrate.

[0021] Furthermore, the solar cell also includes a first passivation layer disposed on the first doped layer and a second passivation layer disposed on the second doped layer; The first fine gate line passes through the first passivation layer and contacts the first doped layer, and the second fine gate line passes through the second passivation layer and contacts the second doped layer.

[0022] Furthermore, at least one of the first passivation layer and the second passivation layer is provided with a plurality of openings at intervals, and at least one of the first fine gate line or the second fine gate line contacts the corresponding first doped layer and the second doped layer through the openings.

[0023] Furthermore, the first fine gate line includes a third body portion and a third extension portion, the third extension portion protruding from the third body portion toward the second fine gate line, at least partially covering the first extension portion; and / or The second fine grid line includes a fourth body portion and a fourth extension portion, wherein the fourth extension portion protrudes from the fourth body portion toward the first fine grid line and at least covers a portion of the second extension portion; The opening is disposed in the region of the first passivation layer and the second passivation layer corresponding to at least one of the third extension and the fourth extension.

[0024] Furthermore, along the second direction, the distance between the centers of two adjacent first doped layers is less than or equal to 3 mm; and / or Along the second direction, the distance between the centers of two adjacent second doped layers is less than or equal to 3 mm.

[0025] Furthermore, the first doped layer and the second doped layer have the same doping type.

[0026] Furthermore, the first doped layer includes a first tunnel layer and a first doped silicon material layer; and / or The second doped layer includes a second tunnel layer and a second doped silicon material layer.

[0027] A battery string includes a solar cell as described in any of the preceding claims and a plurality of solder strips, the solder strips being used to collect the current of the fine grid lines of the solar cell, and adjacent solar cells being connected in series through the solder strips.

[0028] Furthermore, the solder strips extend toward the first direction of the solar cell and are spaced apart along the second direction of the solar cell.

[0029] A photovoltaic module comprising the aforementioned battery string.

[0030] A photovoltaic system comprising the photovoltaic modules described above.

[0031] The beneficial effects achieved by the present invention are as follows: by providing a protruding first extension in the first doped layer, the transmission path of the current in the isolation region is increased, the influence of the isolation region on the current transmission is reduced, the transmission resistance of electrons or holes reaching the collection region is reduced, and the photoelectric conversion efficiency of the solar cell is improved. Attached Figure Description

[0032] Figure 1 This is a planar schematic diagram of a solar cell provided in an embodiment of the present invention; Figure 2 This is yet another planar schematic diagram of the solar cell provided in an embodiment of the present invention; Figure 3 This is another planar schematic diagram of the solar cell provided in an embodiment of the present invention; Figure 4This is another planar schematic diagram of the solar cell provided in an embodiment of the present invention; Figure 5 This is yet another planar schematic diagram of the solar cell provided in an embodiment of the present invention; Figure 6 This is another planar schematic diagram of the solar cell provided in an embodiment of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] In existing solar cell designs, the doped regions below the fine grid line typically employ a uniform-width elongated strip structure, with consistent trench widths between adjacent doped regions. This design restricts current flow in the trench region to the doped layers on either side, resulting in unsatisfactory lateral transport resistance. This structural design severely limits the performance of the cell string, particularly in current collection and transport efficiency, significantly hindering improvements in photoelectric conversion efficiency and bifaciality. This application addresses this issue by incorporating a protruding first extension in the first doped layer, increasing the current transport path in the isolation region, reducing the impact of the isolation region on current transport, lowering the transport resistance of electrons or holes reaching the collection region, and ultimately improving the photoelectric conversion efficiency of the solar cell.

[0035] Example 1 Please see Figures 1 to 3 The present invention is implemented as follows: a solar cell 100 includes: Silicon substrate (not shown in the figure); A first region 10 and a second region 20 are disposed on a silicon substrate. A first doped layer 101 is disposed on the first region 10, and a second doped layer 201 is disposed on the second region 20. The first region 10 and the second region 20 are disposed along a first direction ( Figure 1 Extending from top to bottom in the X direction, and along the second direction ( Figure 1 Arranged in a Y-direction from left to right; A first fine gate line 102 is located in the first region 10, and the first fine gate line 102 is disposed on the first doped layer 101; The second fine gate line 202 is located in the second region 20 and is disposed on the second doped layer 201.

[0036] An isolation zone 30 is located between the first zone 10 and the second zone 20; The first doped layer 101 includes a first body portion 1011 and a plurality of first extension portions 1012, wherein the first extension portions 1012 protrude from the first body portion 1011 in a direction toward the isolation region 30.

[0037] It should be noted that the first extension 1012 refers to the protruding structure extending from the first body 1011 to the isolation region 30. Specifically, it can be formed by photolithography or etching process. Its function is to increase the contact area between the doped layer and the isolation region 30, and provide more lateral transport paths for charge carriers. The isolation region 30 refers to the undoped region that separates the first region 10 from the second region 20. It can be implemented through masking or selective doping processes to reduce light absorption loss and optimize carrier separation efficiency. The first fine gate line 102 refers to the conductive structure covering the first doped layer 101, which can be a metal gate line or a transparent conductive material, used to collect and conduct charge carriers. The second fine gate line 202 refers to the conductive structure covering the second doped layer 201. Specifically, it can be a metal gate line or a transparent conductive material, used to collect and conduct charge carriers.

[0038] Furthermore, several first extensions 1012 protrude from the first body portion 1011 along the direction toward the isolation region 30, thereby forming a doped layer structure with alternating widths. When charge carriers move from the silicon substrate to the first doped layer 101, the first extensions 1012 provide a transport channel perpendicular to the first direction for the charge carriers, allowing the current that originally flowed only along the first direction to diffuse simultaneously along the second direction. The presence of the isolation region 30 reduces parasitic absorption losses of light. In this embodiment, the isolation region 30 is textured, which reduces light reflection losses. The protruding design of the first extensions 1012 allows the current to form a transport network near the isolation region 30, reducing lateral resistance. By adjusting the distribution density and protrusion length of the first extensions 1012, the relationship between optical and electrical performance can be balanced, thereby reducing transmission losses with the same isolation region 30 area, or increasing the area ratio of the isolation region 30 with the same transmission losses.

[0039] In this embodiment, along the first direction, a plurality of first extensions 1012 are periodically distributed on the edge of the first body portion 1011. Specifically, in this embodiment, periodicity may refer to the fact that the interval between two adjacent first extensions 1012 is the same.

[0040] Of course, in other embodiments, periodicity can also refer to the arrangement of the first extensions 1012 in other arrangements with periodic properties. For example, in one embodiment, along the first direction from top to bottom, the intervals between two adjacent first extensions 1012 are arranged in an arithmetic progression; or in another embodiment, along the first direction from top to bottom, the intervals between two adjacent first extensions 1012 are arranged in a proportional progression. The specific arrangement can be considered according to the actual situation and is not limited here. It is only necessary that a number of first extensions 1012 are arranged in a periodic manner.

[0041] It is understood that in other embodiments, the plurality of first extensions 1012 may also be distributed in a non-periodic manner, and the specific design may vary depending on the circumstances, and is not limited here.

[0042] In some embodiments, the solar cell 100 described above can be a back-contact solar cell, or a TOPCon cell (Tunnel Oxide Passivating Contact) cell, etc., in which both the back and light-facing sides contain doped layers. When the solar cell 100 is a back-contact solar cell, the first doped layer 101 and the second doped layer 201 are both disposed on the back surface of the solar cell 100 and separated by the isolation region 30. One of the first doped layer 101 and the second doped layer 201 is a P-type doped layer, and the other is an N-type doped layer. When the solar cell 100 is a TOPCon cell, the structure of the TOPCon cell can be configured as a PolyFinger structure. The first doped layer 101 and the second doped layer 201 are both disposed on the back or light-facing side of the solar cell 100. At least a portion of the first doped layer 101 and the second doped layer 201 are separated by the isolation region 30. The polarity of the first doped layer 101 and the second doped layer 201 is the same, for example, both are P-type doped layers, or both are N-type doped layers.

[0043] Therefore, in the above embodiments, when the solar cell 100 is a back-contact solar cell, one of the first region 10 and the second region 20 is a P-type doped region, and the other is an N-type doped region. For example, if the first region 10 is a P-type doped region, the first doped layer 101 on the first region 10 is a P-type doped layer, and correspondingly, if the second region 20 is an N-type doped region, the second doped layer 201 on the second region 20 is an N-type doped layer; or, if the first region 10 is an N-type doped region, the first doped layer 101 on the first region 10 is an N-type doped layer, and correspondingly, if the second region 20 is a P-type doped region, the second doped layer 201 on the second region 20 is a P-type doped layer.

[0044] The first doped layer 101 can be an N-type doped layer, meaning the polarity of the first doped layer 101 is N-type, and the second doped layer 201 can be a P-type doped layer, meaning the polarity of the second doped layer 201 is P-type. Alternatively, the first doped layer 101 can be a P-type doped layer, meaning the polarity of the first doped layer 101 is P-type, and the second doped layer 201 can be an N-type doped layer, meaning the polarity of the second doped layer 201 is N-type. This invention does not impose specific limitations on these aspects.

[0045] Different doping elements in a doped layer will result in different polarities. For example, when the first doped layer 101 or the second doped layer 201 is a P-type doped layer, the doping element in the P-type doped layer can be boron, gallium, or aluminum. Of course, other doping elements can also be used, and this invention does not impose specific limitations on this. When the first doped layer 101 or the second doped layer 201 is an N-type doped layer, the doping element in the N-type doped layer can be phosphorus, arsenic, or antimony. Of course, other doping elements can also be used, and this invention does not impose specific limitations on this.

[0046] Similarly, in the above embodiments, when the solar cell 100 is a TOPCon cell (Tunnel Oxide Passivating Contact) with two doped layers located on the back and light-facing sides of the cell respectively, the first region 10 and the second region 20 are both located on the light-facing or back-facing side of the solar cell 100. At this time, the first doped layer 101 and the second doped layer 201 are both P-type or N-type doped layers, and the two are separated by the isolation region 30, which is not provided with a doped layer.

[0047] In this embodiment, the negative impact of the isolation region 30 on current transmission is reduced while maintaining or improving optical performance. Thus, a higher proportion of the isolation region 30 can be provided on the back of the cell to improve the bifaciality, or carrier transport losses can be reduced within the same isolation region 30 area, thereby improving the overall conversion efficiency of the solar cell 100.

[0048] Example 2 Please see Figure 2 Furthermore, the second doped layer 201 includes a second body portion 2011 and a plurality of second extension portions 2012, the second extension portions 2012 protruding in a direction toward the isolation region 30.

[0049] Along the first direction, the second extension 2012 refers to a protruding structure extending from the second body 2011 toward the isolation region 30. Specifically, it can be achieved by adjusting the shape of the doped region through a photolithographic mask, and is used to form an additional current collection path at the edge of the isolation region 30.

[0050] Furthermore, the second extension 2012, extending from the second body 2011 towards the isolation region 30, shortens the lateral transport distance of charge carriers from the isolation region 30 to the second doped layer 201. When charge carriers move in the silicon substrate, they can directly enter the second doped layer 201 through the second extension 2012, avoiding the problem of a single transport path caused by the excessive width of the isolation region 30 in conventional structures. For example, the second extension 2012 can be designed in a periodic arrangement or an aperiodic arrangement, similar to the first extension 1012 described above. The specific arrangement can be referenced from the arrangement of the first extension 1012, which will not be elaborated here. Each second extension 2012 covers a local area of ​​the edge of the isolation region 30, forming a multi-point contact transport network.

[0051] In this embodiment, the second extension 2012 reduces the obstruction of current transmission by the isolation region 30, thereby improving the carrier collection efficiency of the second doped layer 201. With the same area ratio of the isolation region 30, carrier transport loss is significantly reduced, allowing for a larger isolation region 30 on the back of the battery to improve optical performance and ultimately increase the bifaciality.

[0052] Example 3 Furthermore, a plurality of first extensions 1012 are arranged at intervals along a first direction, and the distance between two adjacent first extensions 1012 is less than or equal to 1 mm.

[0053] In this embodiment, the spacing refers to the distance between two adjacent first extensions 1012 along the first direction (e.g., the distance between the lower side of the upper first extension 1012 and the upper side of the lower first extension 1012). Specifically, it can be achieved by mask patterning control or laser positioning technology. Reducing this distance can increase the density of current collection points per unit length.

[0054] Furthermore, when the first extensions 1012 are periodically arranged along the first direction, the spacing between two adjacent first extensions 1012 is controlled to be within 1 mm. This dense arrangement causes the first extensions 1012 to form a continuously distributed protrusion structure at the edge of the isolation region 30, thereby forming a multi-path carrier transport channel inside the silicon substrate. When carriers migrate from inside the silicon substrate to the first doped layer 101, the densely arranged extensions shorten the lateral movement distance of the carriers to reach the nearest collection point, while a transport network is formed through the synergistic effect between the first extensions 1012.

[0055] In other embodiments, the distance between two adjacent first extensions 1012 may also be greater than 1 mm, and the specific distance may be adjusted according to different situations, which is not limited here.

[0056] Example 4 Furthermore, a plurality of second extensions 2012 are arranged at intervals along the first direction, and the distance between two adjacent second extensions 2012 is less than or equal to 1 mm.

[0057] In this embodiment, the spacing refers to the distance between two adjacent second extensions 2012 along the first direction (e.g., the distance between the lower side of the upper second extension 2012 and the upper side of the lower second extension 2012). It can also be achieved using mask patterning control or laser positioning technology. Reducing this distance can increase the density of current collection points per unit length.

[0058] Furthermore, when the second extensions 2012 are periodically arranged along the first direction, the spacing between two adjacent second extensions 2012 is controlled to be within 1 mm. This dense arrangement allows the second extensions 2012 to form a continuously distributed protrusion structure at the edge of the isolation region 30, thereby forming a multi-path carrier transport channel inside the silicon substrate. When carriers migrate from the inside of the silicon substrate to the second doped layer 201, the densely arranged extensions shorten the lateral movement distance of the carriers to reach the nearest collection point, while a transport network is formed through the synergistic effect between the second extensions 2012.

[0059] In other embodiments, the distance between two adjacent second extensions 2012 may also be greater than 1 mm, and the specific distance may be adjusted according to different situations, which is not limited here.

[0060] Example 5 Furthermore, along the first direction, the ratio of the sum of the lengths of the plurality of first extensions 1012 to the total length of the first doped layer 101 is greater than or equal to 0.3.

[0061] In this embodiment, the total length of the first doped layer 101 refers to the overall extension length of the first body portion 1011 along the first direction. Specifically, it can be determined by measuring the coverage area of ​​the doped region on the silicon substrate, and is used to calculate the spatial ratio between the extension portion and the body portion. The first extension portion 1012 is periodically arranged along a first direction, and its total length along the first direction is set to be no less than 0.3 times the total length of the first doped layer 101 along the first direction. Through this ratio control, the first extension portion 1012 forms dense current transport paths in the first doped layer 101, allowing charge carriers to diffuse directly to the edge of the isolation region 30 through the first extension portion 1012, reducing the lateral transport distance. With this configuration, the synergistic effect of the first extension portion 1012 and the first body portion 1011 expands the current transport mode of the isolation region 30 from a single lateral path to a multi-path network, thereby reducing the transmission resistance.

[0062] Of course, in other embodiments, the first extension 1012 is periodically arranged along the first direction, and its total length as a percentage of the total length of the first doped layer 101 can also be set to be less than 0.3. The specific arrangement can be considered according to the actual situation and is not limited here.

[0063] Example 6 Furthermore, along the second direction, the ratio of the length of the first extension 1012 to the length of the first body portion 1011 is greater than or equal to 1.5.

[0064] The first body portion 1011 refers to the main body of the first doped layer 101, which can be implemented using a continuous doped layer structure, serving as the main conductive channel to undertake the longitudinal transport function of charge carriers. The length ratio refers to the proportional relationship between the extension dimension of the first extension portion 1012 in the second direction and the basic dimension of the first body portion 1011 in the second direction. Specifically, it can be achieved by adjusting the lateral width of the first extension portion 1012, and this ratio controls the distribution relationship between the lateral conductive area and the longitudinal conductive area.

[0065] In this embodiment, when the length of the first extension 1012 in the second direction reaches more than 150% of the length of the first body 1011 in the second direction, the lateral conductive network formed by the extension can significantly increase the effective cross-sectional area for lateral carrier migration. This configuration allows carriers on both sides of the isolation region 30 to be laterally transported through the conductive channels formed by the first extension 1012, reducing resistance losses caused by relying solely on the longitudinal transmission of the first body 1011 in conventional designs. The length ratio of the first extension 1012 to the first body 1011 optimizes the distribution density of the current transmission path, maintaining the longitudinal conductivity of the first body 1011 while forming redundant conductive channels through the lateral expansion of the first extension 1012.

[0066] This configuration significantly reduces the obstruction of carrier transport by the isolation region 30, allowing for a reduction in lateral transport resistance loss while maintaining the same area ratio of the isolation region 30, or enabling a larger isolation region 30 while maintaining the same level of transport loss. This optimization balances the conflict between optical and electrical performance, improving the difaciality while maintaining the stability of the cell conversion efficiency.

[0067] It should be noted that in other embodiments, the ratio of the length of the first extension 1012 in the second direction to the length of the first body portion 1011 in the second direction can also be set to less than 1.5. The specific ratio can be considered according to different situations and is not limited here.

[0068] Example 7 Furthermore, along the first direction, the ratio of the sum of the lengths of the second extensions 2012 to the total length of the second doped layer 201 is greater than or equal to 0.3.

[0069] In this embodiment, the total length of the second doped layer 201 refers to the overall extension length of the second body portion 2011 along the first direction. Specifically, it can be determined by measuring the coverage area of ​​the doped region on the silicon substrate, and is used to calculate the spatial ratio between the extension portion and the body portion. The second extension 2012 is periodically arranged along the first direction, and its total length along the first direction is set to be no less than 0.3 times the total length of the second doped layer 201 in the first direction. Through this ratio control, the second extension 2012 forms dense current transport paths in the second doped layer 201, allowing charge carriers to diffuse directly to the edge of the isolation region 30 through the second extension 2012, reducing the lateral transport distance. With this configuration, the synergistic effect of the second extension 2012 and the second body 2011 expands the current transport mode of the isolation region 30 from a single lateral path to a multi-path network, thereby reducing the transmission resistance.

[0070] Of course, in other embodiments, the second extension 2012 is periodically arranged along the first direction, and its total length as a percentage of the total length of the second doped layer 201 can also be set to be less than 0.3. The specific arrangement can be considered according to the actual situation and is not limited here.

[0071] Example 8 Furthermore, along the second direction, the ratio of the length of the second extension 2012 to the length of the second body 2011 is greater than or equal to 1.5.

[0072] The second body portion 2011 refers to the main body of the second doped layer 201, which can be implemented using a continuous doped layer structure, serving as the main conductive channel to perform the longitudinal transport function of charge carriers. The length ratio refers to the proportional relationship between the extension dimension of the second extension portion 2012 in the second direction and the basic dimension of the second body portion 2011 in the second direction. Specifically, it can be achieved by adjusting the lateral width of the second extension portion 2012, and this ratio controls the distribution relationship between the lateral conductive area and the longitudinal conductive area.

[0073] In this embodiment, when the length of the second extension 2012 in the second direction reaches more than 150% of the length of the second body 2011, the lateral conductive network formed by the extension can significantly increase the effective cross-sectional area for lateral carrier migration. This configuration allows carriers on both sides of the isolation region 30 to be laterally transported through the conductive channels formed by the second extension 2012, reducing the resistance loss caused by relying solely on the longitudinal transmission of the second body 2011 in conventional designs. The length ratio of the second extension 2012 to the second body 2011 optimizes the distribution density of the current transmission path, maintaining the longitudinal conductivity of the second body 2011 while forming redundant conductive channels through the lateral expansion of the second extension 2012.

[0074] This configuration significantly reduces the obstruction of carrier transport by the isolation region 30, allowing for a reduction in lateral transport resistance loss while maintaining the same area ratio of the isolation region 30, or enabling a larger isolation region 30 while maintaining the same level of transport loss. This optimization balances the conflict between optical and electrical performance, improving the difaciality while maintaining the stability of the cell conversion efficiency.

[0075] It should be noted that in other embodiments, the ratio of the length of the second extension 2012 to the length of the second body 2011 may also be set to less than 1.5. The specific ratio can be considered according to different situations and is not limited here.

[0076] Example 9 Please see Figure 4 Furthermore, along the first direction, the first extension 1012 and the second extension 2012 are staggered; and / or The first extension 1012 and the second extension 2012 are aligned and at least partially connected to each other; and / or The first extension 1012 and the second extension 2012 are aligned and spaced apart.

[0077] The staggered arrangement means that the first extension 1012 and the second extension 2012 do not overlap in the planar projection. Specifically, this can be achieved by adjusting the positional deviation of the mask pattern. This layout can form staggered carrier transport channels. Interconnection refers to the physical contact formed between the extensions, which can be achieved by adjusting the overlapping area of ​​the mask pattern. This structure can shorten the lateral transport distance of charge carriers.

[0078] Specifically, when the first extension 1012 and the second extension 2012 are staggered, charge carriers can be directly transported from the sidewall of the first extension 1012 to the adjacent sidewall of the second extension 2012, forming a multidirectional transport path. When the first extension 1012 and the second extension 2012 are aligned and connected to each other, the doped layers on both sides of the isolation region 30 form a bridging structure through the first extension 1012 and the second extension 2012, allowing charge carriers to directly traverse the isolation region 30 along the connection point. When the first extension 1012 and the second extension 2012 are aligned but spaced apart, charge carriers achieve cross-region transport through the electric field gradient formed at the tip of the extension. These three configurations can be combined and applied according to the doped layer spacing and the width of the isolation region 30.

[0079] In this embodiment, extensions are provided on both adjacent first doped layers 101 and second doped layers 201. The design can be optimized according to requirements to control the width of the first extension 1012 and the second extension 2012 on the first doped layer 101 and the second doped layer 201, as well as whether they are aligned or staggered, so as to achieve the best current collection and transmission effect. This arrangement can also optimize the overall area of ​​the isolation region 30 and further improve the overall performance of the solar cell 100.

[0080] In some embodiments, when the solar cell 100 is a back-contact solar cell, the first extension 1012 and the second extension 2012 are staggered or aligned, and the first extension 1012 and the second extension 2012 are spaced apart; or a portion of the first extension 1012 and the second extension 2012 are staggered, a portion of the first extension 1012 and the second extension 2012 are aligned, and the first extension 1012 and the second extension 2012 are spaced apart. When the solar cell 100 is a back-contact solar cell, since one of the first region 10 and the second region 20 is a P-type doped region and the other is an N-type doped region, the first doped layer 101 disposed on the first region 10 and the second doped layer 201 disposed on the second region 20 have different polarities. Therefore, it is necessary to stagger the first extension 1012 and the second extension 2012 or align the first extension 1012 and the second extension 2012 and space them apart to avoid the two doped layers of different polarities from being directly connected, which would cause a short circuit.

[0081] In some embodiments, when the solar cell 100 is a TOPCon cell or similar cell with doped layers on both the back and light-facing surfaces, the first extension 1012 and the second extension 2012 are staggered along the first direction; and / or the first extension 1012 and the second extension 2012 are aligned, and at least a portion of the first extension 1012 and the second extension 2012 are connected to each other; and / or the first extension 1012 and the second extension 2012 are aligned, and the first extension 1012 and the second extension 2012 are spaced apart. Since both the first region 10 and the second region 20 of the TOPCon cell are P-type doped regions or N-type doped regions, the first doped layer 101 on the first region 10 and the second doped layer 201 on the second region 20 have the same polarity. Therefore, when the first extension 1012 and the second extension 2012 are aligned, they can be connected to each other without causing a short circuit, which can increase the area of ​​the local doped layer.

[0082] Example 10 Please see Figure 3 Furthermore, the first fine grid line 102 includes a third body portion 1021 and a third extension portion 1022, the third extension portion 1022 protruding from the third body portion 1021 toward the direction close to the second fine grid line 202, at least covering a portion of the first extension portion 1012; and / or The second fine grid line 202 includes a fourth body portion 2021 and a fourth extension portion 2022. The fourth extension portion 2022 protrudes from the fourth body portion 2021 toward the direction close to the first fine grid line 102, at least covering a portion of the second extension portion 2012.

[0083] In this embodiment, the third body portion 1021 refers to the main body portion of the first fine gate line 102, which can be implemented using a continuous or discontinuous metal conductive layer, used to extend along the first direction and collect the current of the first doped layer 101. The third extension portion 1022 refers to a protruding structure extending from the third body portion 1021 toward the second fine gate line 202, which can be implemented using a metal conductive layer integrally formed with the third body portion 1021, and its coverage of the first extension portion 1012 can enhance the current collection efficiency of the first extension portion 1012 region; The fourth body portion 2021 refers to the main body portion of the second fine gate line 202, which can be implemented using a continuous or discontinuous metal conductive layer, and is used to extend along the first direction and collect the current of the second doped layer 201. The fourth extension portion 2022 refers to a protruding structure extending from the fourth body portion 2021 toward the first fine gate line 102, which can be implemented using a metal conductive layer integrally formed with the fourth body portion 2021, and its coverage of the second extension portion 2012 can enhance the current collection efficiency of the second extension portion 2012 region.

[0084] Specifically, when the third extension 1022 covers the first extension 1012, the contact area between the first fine gate line 102 and the first extension 1012 can be increased, shortening the transport path of charge carriers from the first extension 1012 to the first fine gate line 102, thereby reducing the lateral transport resistance. Similarly, when the fourth extension 2022 covers the second extension 2012, the carrier transport loss in the region of the second extension 2012 can be reduced. When the third extension 1022 and the fourth extension 2022 protrude from each other, they form an interlaced or overlapping conductive network above the isolation region 30, further optimizing the current transport path of the isolation region 30, enabling charge carriers to be transported through the first extension 1012 and the second extension 2012 of the first fine gate line 102 and the second fine gate line 202.

[0085] In other words, by covering the first extension 1012 of the first doped layer 101 with the third extension 1022 of the first fine grid line 102, and by covering the second extension 2012 of the second doped layer 201 with the fourth extension 2022 of the second fine grid line 202, the current collection efficiency is improved, the lateral transport distance of charge carriers in the isolation region 30 is reduced, and thus the transport loss is reduced. Therefore, with the same area ratio of the isolation region 30, the conversion efficiency of the battery can be improved; or, while maintaining the same level of transport loss, the area ratio of the isolation region 30 can be increased to improve the bifaciality.

[0086] In some embodiments, multiple third extensions 1022 and multiple fourth extensions 2022 may be reasonably provided according to actual conditions, such as two, three, four, etc., to further improve current collection efficiency, reduce the lateral transmission distance of charge carriers in the isolation region 30, and thus reduce transmission loss.

[0087] Example 11 Please see Figure 5 Furthermore, along the first direction, the third extension 1022 and the fourth extension 2022 are staggered; and / or The third extension 1022 and the fourth extension 2022 are aligned, and at least a portion of the third extension 1022 and the fourth extension 2022 are interconnected; and / or The third extension 1022 and the fourth extension 2022 are aligned and spaced apart.

[0088] In this embodiment, when the third extension 1022 and the fourth extension 2022 are staggered, their conductive areas form alternating current channels in the isolation region 30, reducing the increase in local resistance caused by path overlap. When the third extension 1022 and the fourth extension 2022 are aligned and connected to each other, the third extension 1022 and the fourth extension 2022 form a continuous conductive bridging structure in the isolation region 30. Charge carriers can be directly transmitted to adjacent fine gate lines through the bridging structure, reducing lateral transmission loss. When the third extension 1022 and the fourth extension 2022 are aligned but spaced apart, the third extension 1022 and the fourth extension 2022 avoid structural redundancy by controlling the spacing while maintaining position alignment, and maintain sufficient conductive coverage with limited material usage. The above three arrangement methods can be flexibly selected or combined according to actual needs such as the width of the isolation area 30, the density, length, and width of the first extension 1012 and the second extension 2012, to optimize the current transmission path.

[0089] This embodiment solves the problem of optimizing the current transmission path of the third extension 1022 and the fourth extension 2022 in the isolation region 30. By reducing the transmission resistance through multi-mode arrangement design, it provides a structural basis for increasing the area ratio of the isolation region 30, thereby improving the bifaciality of the battery.

[0090] In some embodiments, when the solar cell 100 is a back-contact solar cell, the third extension 1022 and the fourth extension 2022 are either staggered or aligned, and spaced apart. When the solar cell 100 is a back-contact solar cell, since one of the first region 10 and the second region 20 is a P-type doped region and the other is an N-type doped region, the first doped layer 101 disposed on the first region 10 and the second doped layer 201 disposed on the second region 20 have different polarities. Therefore, the third extension 1022 and the fourth extension 2022 need to be staggered or aligned, and spaced apart, to avoid a short circuit caused by direct connection of two grid lines of different polarities.

[0091] In some embodiments, when the solar cell 100 is a TOPCon cell with two doped layers located on the back and front surfaces of the cell respectively, the third extension 1022 and the fourth extension 2022 are staggered along the first direction; and / or the third extension 1022 and the fourth extension 2022 are aligned, and at least part of the third extension 1022 and the fourth extension 2022 are connected to each other; and / or the third extension 1022 and the fourth extension 2022 are aligned, and the third extension 1022 and the fourth extension 2022 are spaced apart. Both the first region 10 and the second region 20 of the TOPCon cell are P-type or N-type doped regions. The first doped layer 101 on the first region 10 and the second doped layer 201 on the second region 20 have the same polarity. Therefore, when the third extension 1022 and the fourth extension 2022 are aligned, they can be connected to each other without causing a short circuit. In this way, the charge carriers generated by illumination in the spacer region 30, the first doped layer 101, and the second doped layer 201 can be transported nearby through the third extension 1022 and the fourth extension 2022. The third extension 1022 and the fourth extension 2022 are metal grid lines with extremely low resistivity, which is beneficial for the conduction of charge carriers, reduces the transport loss of charge carriers, further reduces the internal series resistance loss of the solar cell 100, and improves the photoelectric conversion efficiency of the solar cell 100.

[0092] Example 12 Furthermore, both the first region 10 and the second region 20 are located on the back side of the silicon substrate, and the first region 10 and the second region 20 are at least partially isolated by the isolation region 30.

[0093] Specifically, the back side of the silicon substrate refers to the non-light-receiving area in the battery structure. A flat surface can be formed by chemical polishing or mechanical grinding processes to construct the back electrode structure. At least partial isolation refers to the existence of locally continuous or discontinuous isolation structures in the spatial distribution of the isolation zone 30. Specifically, it can be achieved by using segmented trench or grid-like isolation structures to balance electrical isolation requirements and structural stability.

[0094] In this embodiment, by confining the first region 10 and the second region 20 on the back side of the silicon substrate, the first doped layer 101 and the second doped layer 201 are concentrated on the non-light-receiving surface. The partial isolation design of the isolation region 30 forms a controllable carrier transport channel between adjacent first doped layers 101 and second doped layers 201. The isolation region 30 can block recombination losses caused by lateral diffusion of carriers, while the unisolated regions maintain the necessary structural connection strength. When carriers are transported from the interior of the silicon substrate to the back electrode, the spatial distribution of the isolation region 30 can shorten the lateral transport distance and reduce resistance loss. At the same time, the concentrated arrangement of the first doped layer 101 and the second doped layer 201 on the back side, by optimizing the width and distribution density of the isolation region 30, can achieve a balance between improving the back light reflectivity and reducing carrier transport loss.

[0095] Example 13 Furthermore, the first region 10 and the second region 20 are both located on the back side of the silicon substrate, or the first region 10 and the second region 20 are located on the front side of the silicon substrate.

[0096] In this embodiment, when both the first region 10 and the second region 20 are located on the back side, the isolation region 30, the first extension 1012 and the second extension 2012 form a carrier transport path, reducing the influence of the lateral resistance of the isolation region 30 on the current transport. At this time, the bifaciality of the back side is improved while the carrier collection efficiency is maintained. When the first region 10 and the second region 20 are on the front, the staggered coverage design of the first extension 1012 and the second extension 2012 with the first fine grid line 102 and the second fine grid line 202 enables multi-dimensional transport of charge carriers within the light absorption layer. For example, the overlapping area of ​​the first extension 1012 and the third extension 1022 forms a local high-density contact point, shortening the lateral migration distance of charge carriers. In this embodiment, the layout of the doped regions can be selected according to the application scenario. For example, in the case of a ground power station, a back-side arrangement is preferred to utilize reflected light, while in the case of building-integrated photovoltaics, a front-side arrangement is used to optimize charge carrier collection under low-light conditions.

[0097] This configuration, when used on the back side, reduces the resistance of the isolation region 30 through the transmission path, expanding the area of ​​the isolation region 30 while maintaining carrier collection efficiency, thereby improving the bifaciality. When used on the front side, the carrier collection path is optimized through the coverage design of the first extension 1012 and the second extension 2012 with the first fine grid line 102 and the second fine grid line 202, enhancing current output under low-light conditions. This allows the battery structure to be optimized for surface layout in different application scenarios; for example, a back-side configuration can be chosen for scenarios requiring high reflective light utilization, while a front-side configuration can be chosen for scenarios requiring maximum front-side photoelectric conversion.

[0098] Example 14 Furthermore, the solar cell 100 also includes a first passivation layer (not shown) disposed on the first doped layer 101 and a second passivation layer (not shown) disposed on the second doped layer 201. The first fine gate line 102 passes through the first passivation layer and contacts the first doped layer 101, and the second fine gate line 202 passes through the second passivation layer and contacts the second doped layer 201.

[0099] Specifically, the first passivation layer refers to a non-conductive thin film layer covering the surface of the first doped layer 101, which can be made of silicon oxide, silicon nitride, or aluminum oxide, and is used to reduce the carrier recombination rate on the surface of the first doped layer 101. The second passivation layer refers to a non-conductive thin film layer covering the surface of the second doped layer 201, and its material selection is the same as that of the first passivation layer, used to isolate the metal contact area from direct contact with the second doped layer 201. The first fine gate line 102 passing through the first passivation layer and the second fine gate line 202 passing through the second passivation layer refer to the formation of local openings 40 in the first or second passivation layer by laser ablation or chemical etching, so that the metal electrode forms point-like or line-like contacts with the first doped layer 101 and the second doped layer 201. This can be achieved using selective emitter technology, and is used to reduce contact resistance while maintaining passivation integrity.

[0100] Furthermore, the first passivation layer covers the surface of the first body portion 1011 and the first extension portion 1012 of the first doped layer 101, and forms an electrical connection with the first fine gate line 102 through periodically distributed contact openings. The second passivation layer covers the second doped layer 201 in the same manner, and forms an electrical connection with the second fine gate line 202 through periodically distributed contact openings 40. The continuous coverage of the first and second passivation layers effectively suppresses the dangling bonds and defect state density on the surfaces of the first doped layer 101 and the second doped layer 201, while the first and second fine gate lines 102 directly penetrate the first and second passivation layers respectively at the contact openings, forming low-resistance current channels. This selective contact structure allows the first and second passivation layers to maintain a complete passivation effect in the non-contact areas, while reducing the series resistance in the contact areas through local metal-semiconductor direct contact, thereby effectively reducing the recombination rate on the surfaces of the first and second doped layers 101 and 201, ultimately improving the battery conversion efficiency and bifaciality performance.

[0101] Example 15 Please see Figure 6 Furthermore, at least one of the first passivation layer and the second passivation layer is provided with a plurality of openings 40 at intervals, and at least one of the first fine gate line 102 or the second fine gate line 202 contacts the corresponding first doped layer 101 and second doped layer 201 through the openings 40.

[0102] In this embodiment, the multiple openings 40 (consistent with the contact openings mentioned above) are a hole structure distributed discontinuously on the surfaces of the first passivation layer and the second passivation layer. Specifically, they can be achieved by laser ablation or chemical etching processes. The passivation protection and conductive contact area are balanced by controlling the density and spacing of the openings 40.

[0103] The first fine gate line 102 and the second fine gate line 202 contacting the corresponding first doped layer 101 and second doped layer 201 through the opening 40 means that the metal electrode penetrates the passivation layer through the opening 40 to form an ohmic contact with the semiconductor material. This can be achieved by screen printing or electroplating, and the passivation layer damage area is reduced by local contact. In this embodiment, the opening 40 is generally rectangular. In other embodiments, the opening 40 may also be circular, triangular, racetrack-shaped, etc., and is not limited here.

[0104] Specifically, the openings 40 on the surfaces of the first and second passivation layers are periodically spaced, ensuring that the first fine gate line 102 and the second fine gate line 202 only directly contact the first doped layer 101 and the second doped layer 201 in the opening 40 region. The first and second passivation layers remain intact between the openings 40 and other openings 40, effectively suppressing surface recombination in non-contact areas. By controlling the spacing and size ratio of the openings 40, the protective effect of the first and second passivation layers on the surfaces of the first doped layer 101 and the second doped layer 201 is preserved, while simultaneously forming a discretely distributed array of conductive contact points. When charge carriers transverse within the first doped layer 101 and the second doped layer 201, transport paths can be formed through multiple contact points, reducing transverse resistance.

[0105] Example 16 Please continue reading. Figure 6 Furthermore, the first fine grid line 102 includes a third body portion 1021 and a third extension portion 1022, the third extension portion 1022 protruding from the third body portion 1021 toward the second fine grid line 202, at least covering a portion of the first extension portion 1012; and / or The second fine grid line 202 includes a fourth body portion 2021 and a fourth extension portion 2022. The fourth extension portion 2022 protrudes from the fourth body portion 2021 toward the first fine grid line 102 and at least covers a portion of the second extension portion 2012. The opening 40 is disposed in the region of the first passivation layer and the second passivation layer corresponding to at least one of the third extension 1022 and the fourth extension 2022.

[0106] In some embodiments, the opening 40 may also be disposed in the region of the first passivation layer or the second passivation layer corresponding to at least one of the third body portion 1021 and the fourth body portion 2021, and the openings 40 are arranged at intervals.

[0107] The above embodiments, by providing openings 40 in the passivation layer regions beneath the first fine gate line 102 and the second fine gate line 202, ensure that the first fine gate line 102 and the second fine gate line 202 only directly contact the first doped layer 101 and the second doped layer 201 in the opening 40 region. The first and second passivation layers remain intact between the openings 40, effectively suppressing surface recombination in non-contact areas. By controlling the spacing and size ratio of the openings 40, the protective effect of the first and second passivation layers on the surfaces of the first doped layer 101 and the second doped layer 201 is preserved, while also forming a discretely distributed array of conductive contact points. When charge carriers transverse within the first doped layer 101 and the second doped layer 201, a transmission path can be formed through multiple contact points, reducing transverse resistance.

[0108] In this embodiment, the openings 40 are concentrated in the coverage area of ​​the third extension 1022 and the fourth extension 2022. By increasing the density of local contact points, the extraction efficiency of charge carriers in the third extension 1022 and the fourth extension 2022 is enhanced. This arrangement transforms the current transmission path from the traditional lateral diffusion to a network combining longitudinal transmission along the third extension 1022 and the fourth extension 2022 with lateral diffusion, effectively reducing the transmission loss of the isolation region 30.

[0109] Example 17 Furthermore, along the second direction, the distance between the centers of two adjacent first doped layers 101 is less than or equal to 3 mm; and / or Along the second direction, the distance between the centers of two adjacent second doped layers 201 is less than or equal to 3 mm.

[0110] This configuration shortens the distance, compressing the lateral transport path of charge carriers within the silicon substrate and thus reducing recombination losses.

[0111] Specifically, by limiting the distance between the centers of two adjacent first doped layers 101 and the distance between the centers of two adjacent second doped layers 201 to within 3 mm, the lateral migration path of charge carriers from the generation location to the collection region is significantly shortened. This reduces the lateral transport resistance of the isolation region 30, allowing for an increase in the area ratio of the isolation region 30 while maintaining the same transport efficiency. Simultaneously, the compact distribution of the first doped layers 101 and the second doped layers 201 with the isolation region 30 optimizes the current transport path, avoiding carrier recombination caused by long-distance migration, thereby balancing the conflict between optical and electrical performance.

[0112] It is understood that in other embodiments, the distance between the centers of two adjacent first doped layers 101 and the distance between the centers of two adjacent second doped layers 201 along the second direction may also be other values. For example, in one embodiment, the distance between the centers of two adjacent first doped layers 101 along the second direction is less than or equal to 2 mm, and / or the distance between the centers of two adjacent second doped layers 201 along the second direction is less than or equal to 2.5 mm; as another example, in another embodiment, the distance between the centers of two adjacent first doped layers 101 along the second direction is less than or equal to 2.5 mm, and / or the distance between the centers of two adjacent second doped layers 201 along the second direction is less than or equal to 4 mm. The specific design can be made according to the actual situation and is not limited here.

[0113] Example 18 Furthermore, the first doped layer 101 and the second doped layer 201 have the same doping type.

[0114] In this embodiment, when the doping types of the first doped layer 101 and the second doped layer 201 are the same, the solar cell 100 can be a TOPCon cell, and both the first doped layer 101 and the second doped layer 201 are N+ type heavily doped regions. Similarly, the first doped layer 101 and the second doped layer 201 can also be P+ type heavily doped regions, which is not limited here.

[0115] In other embodiments, the doping types of the first doped layer 101 and the second doped layer 201 may also be different. In such cases, the solar cell 100 may be an IBC cell, the first doped layer 101 is a P+ type doped region, and the second doped layer 201 is an N+ type doped region.

[0116] Example 19 Furthermore, the first doped layer 101 includes a first tunnel layer (not shown) and a first doped silicon material layer; and / or The second doped layer 201 includes a second tunnel layer (not shown) and a second doped silicon material layer.

[0117] In this embodiment, the first tunnel layer refers to an ultrathin dielectric layer located between the silicon substrate and the first doped silicon material layer. Specifically, it can be implemented using silicon oxide or silicon nitride layers. Its function is to achieve selective carrier transport through quantum tunneling while suppressing interface recombination. The first doped silicon material layer refers to a conductive layer covering the tunnel layer. Specifically, it can be implemented using phosphorus-doped or boron-doped polycrystalline silicon or amorphous silicon layers. Its function is to provide lateral conductive channels to reduce carrier transport resistance. The structure and function mechanism of the second tunnel layer and the second doped silicon material layer are the same as the former, and will not be described in detail here.

[0118] Specifically, a first tunnel layer and a first doped silicon material layer, and / or a second tunnel layer and a second doped silicon material layer are sequentially formed on the surface of a silicon substrate. This allows charge carriers to tunnel through the ultrathin dielectric layer into the conductive layer, achieving low-resistance transport. The presence of the tunnel layer effectively reduces recombination losses in the metal contact region, while the doped silicon material layer rapidly guides charge carriers to the fine gate lines through a lateral conductive network. For the second doped layer 201, the second tunnel layer and the second doped layer form a similar composite structure. Together, they form a conductive path in the isolation region 30, reducing resistance losses during lateral transport. This configuration allows the first doped layer 101 and the second doped layer 201 to maintain surface passivation performance while improving transport efficiency through the continuous distribution of the conductive layer.

[0119] Example 20 A battery string (not shown) includes a plurality of solar cells 100 as described above and a plurality of solder strips, wherein the solder strips are used to collect the current of the fine grid lines of the solar cells 100, and adjacent solar cells 100 are connected in series through a solder strip.

[0120] Furthermore, the solder strips extend toward the first direction of the solar cell 100 and are spaced apart along the second direction of the solar cell 100.

[0121] A photovoltaic module (not shown) includes the aforementioned battery string.

[0122] A photovoltaic system (not shown) includes the photovoltaic module described above.

[0123] The beneficial effects achieved by the present invention are as follows: the solar cell 100, the cell string, the photovoltaic module, and the photovoltaic system of the present invention, due to the protruding first extension 1012 provided in the first doped layer 101, increase the current transmission path of the isolation region 30, reduce the influence of the isolation region 30 on current transmission, reduce the transmission resistance of electrons or holes to the collection region, and improve the photoelectric conversion efficiency of the solar cell 100.

[0124] It is understood that those skilled in the art can combine various implementation methods in the above embodiments under the guidance of the above examples to obtain technical solutions with multiple implementation methods.

[0125] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A battery string, characterized in that, include: Several solar cells; A plurality of solder strips are provided, the solder strips being used to collect the current of the fine grid lines of the solar cell, and two adjacent solar cells are connected in series through the solder strips, the solder strips extending toward a second direction of the solar cell and spaced apart along a first direction of the solar cell; The solar cell includes: silicon substrate; The silicon substrate has a first region and a second region. The first region has a first doped layer and the second region has a second doped layer. The first region and the second region extend along a first direction and are arranged along a second direction. A first fine gate line located in the first region, the first fine gate line being disposed on the first doped layer; The second fine gate line is located in the second region and is disposed on the second doped layer. An isolation zone is established between the first region and the second region; The first doped layer includes a first body portion and a plurality of first extension portions, wherein the first extension portions protrude from the first body portion in a direction toward the isolation region.

2. The battery string as described in claim 1, characterized in that, The second doped layer includes a second body portion and a plurality of second extension portions, the second extension portions protruding in a direction toward the isolation region.

3. The battery string as described in claim 1, characterized in that, A plurality of the first extension portions are arranged at intervals along the first direction, and the distance between two adjacent first extension portions is less than or equal to 1 mm.

4. The battery string as described in claim 2, characterized in that, Several second extensions are arranged at intervals along the first direction, and the distance between two adjacent second extensions is less than or equal to 1 mm.

5. The battery string as described in claim 1, characterized in that, Along the first direction, the ratio of the sum of the lengths of the first extensions to the total length of the first doped layer is greater than or equal to 0.

3.

6. The battery string as described in claim 1, characterized in that, Along the second direction, the ratio of the length of the first extension to the length of the first body portion is greater than or equal to 1.

5.

7. The solar cell according to claim 2, characterized in that, Along the first direction, the ratio of the sum of the lengths of the plurality of second extensions to the total length of the second doped layer is greater than or equal to 0.

3.

8. The battery string as described in claim 2, characterized in that, Along the second direction, the ratio of the length of the second extension to the length of the second body is greater than or equal to 1.

5.

9. The battery string as described in claim 2, characterized in that, Along the first direction, the first extension and the second extension are staggered; and / or The first extension and the second extension are aligned and at least partially connected to each other; and / or The first extension and the second extension are aligned and spaced apart.

10. The battery string as described in claim 2, characterized in that, The first fine grid line includes a third body portion and a third extension portion, the third extension portion protruding from the third body portion toward the second fine grid line, at least covering a portion of the first extension portion; and / or The second fine grid line includes a fourth body portion and a fourth extension portion, the fourth extension portion protruding from the fourth body portion toward the first fine grid line, at least covering a portion of the second extension portion.

11. The battery string as claimed in claim 10, characterized in that, Along the first direction, the third extension and the fourth extension are staggered; and / or The third extension and the fourth extension are aligned, and at least a portion of the third extension and the fourth extension are interconnected; and / or The third extension and the fourth extension are aligned and spaced apart.

12. The battery string as claimed in claim 1, characterized in that, Both the first region and the second region are located on the back side of the silicon substrate, and the first region and the second region are at least partially isolated by the isolation region.

13. The battery string as claimed in claim 1, characterized in that, The first region and the second region are both located on the back side of the silicon substrate, or the first region and the second region are located on the front side of the silicon substrate.

14. The battery string as claimed in claim 1, characterized in that, The solar cell further includes a first passivation layer disposed on the first doped layer and a second passivation layer disposed on the second doped layer; The first fine gate line passes through the first passivation layer and contacts the first doped layer, and the second fine gate line passes through the second passivation layer and contacts the second doped layer.

15. The battery string as described in claim 14, characterized in that, At least one of the first passivation layer and the second passivation layer is provided with a plurality of openings at intervals, and at least one of the first fine gate line or the second fine gate line contacts the corresponding first doped layer and the second doped layer through the openings.

16. The battery string as described in claim 15, characterized in that, The first fine grid line includes a third body portion and a third extension portion, the third extension portion protruding from the third body portion toward the second fine grid line, at least partially covering the first extension portion; and / or The second fine grid line includes a fourth body portion and a fourth extension portion, wherein the fourth extension portion protrudes from the fourth body portion toward the first fine grid line and at least covers a portion of the second extension portion; The opening is disposed in the region of the first passivation layer and the second passivation layer corresponding to at least one of the third extension and the fourth extension.

17. The battery string as claimed in claim 1, characterized in that, Along the second direction, the distance between the centers of two adjacent first doped layers is less than or equal to 3 mm; and / or Along the second direction, the distance between the centers of two adjacent second doped layers is less than or equal to 3 mm.

18. The battery string as claimed in claim 1, characterized in that, The first doped layer and the second doped layer have the same doping type.

19. The battery string as claimed in claim 1, characterized in that, The first doped layer includes a first tunnel layer and a first doped silicon material layer; and / or The second doped layer includes a second tunnel layer and a second doped silicon material layer.

20. A photovoltaic module, characterized in that, Includes the battery string as described in any one of claims 1-19.

21. A photovoltaic system, characterized in that, Includes the photovoltaic module described in claim 20 above.

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