CN217881528U

CN217881528U - Solar cell, conductive contact structure thereof, cell module and photovoltaic system

Info

Publication number: CN217881528U
Application number: CN202221590035.1U
Authority: CN
Inventors: 石强; 陈刚
Original assignee: Zhejiang Aiko Solar Energy Technology Co Ltd; Guangdong Aiko Technology Co Ltd; Tianjin Aiko Solar Energy Technology Co Ltd; Zhuhai Fushan Aixu Solar Energy Technology Co Ltd
Current assignee: Zhejiang Aiko Solar Energy Technology Co Ltd; Guangdong Aiko Technology Co Ltd; Tianjin Aiko Solar Energy Technology Co Ltd; Zhuhai Fushan Aixu Solar Energy Technology Co Ltd
Priority date: 2022-06-23
Filing date: 2022-06-23
Publication date: 2022-11-22
Anticipated expiration: 2032-06-23

Abstract

The application is suitable for the technical field of solar cells, and provides a solar cell, a conductive contact structure of the solar cell, a cell module and a photovoltaic system. The conductive contact structure of the solar cell comprises a conductive contact layer and a composite electrode, wherein the conductive contact layer is arranged between the composite electrode and a silicon substrate, the composite electrode comprises a composite fine grid and a composite main grid, and the composite fine grid comprises an aluminum fine grid and a silver fine grid which are sequentially arranged on the silicon substrate; the composite main grid comprises an aluminum main grid and a silver main grid which are sequentially arranged on a silicon substrate. Therefore, due to the adoption of the conductive contact layer and the aluminum-silver composite electrode, ohmic contact can be formed by depending on the doping of the aluminum grid line, and the current can be effectively led out by utilizing the strong conductivity of the silver grid line. Furthermore, since the aluminum grid line serves as a contact electrode, the thickness of the silver grid line can be made thinner. Thus, the cost can be reduced while the photoelectric conversion efficiency is ensured.

Description

Solar cell, conductive contact structure thereof, cell module and photovoltaic system

Technical Field

The application belongs to the technical field of solar cells, and particularly relates to a solar cell and a conductive contact structure, a cell module and a photovoltaic system thereof.

Background

Solar cell power generation is a sustainable clean energy source that can convert sunlight into electrical energy using the photovoltaic effect of semiconductor p-n junctions.

In the related art, the front metal electrode of the P-type TOPCon battery is a silver-aluminum mixed electrode formed by silver-aluminum paste, and the cost of the silver-aluminum mixed electrode is higher than that of a pure silver electrode. In addition, a P + doping layer is required to be arranged below the silver-aluminum mixed electrode to form ohmic contact. That is, a boron diffusion layer or a P + polysilicon layer must be formed under the ag-al mixed electrode. Therefore, the process is complex, the cost is high, and the industrialization is not facilitated.

Therefore, how to reduce the cost of manufacturing the electrode of the solar cell becomes a problem to be solved urgently.

SUMMERY OF THE UTILITY MODEL

The application provides a solar cell and a conductive contact structure, a cell module and a photovoltaic system thereof, aiming at solving the problem of how to reduce the cost of manufacturing electrodes of the solar cell.

In a first aspect, the conductive contact structure of a solar cell provided by the present application includes a conductive contact layer and a composite electrode, the conductive contact layer is disposed between the composite electrode and a silicon substrate, the composite electrode includes a composite fine grid and a composite main grid, and the composite fine grid includes an aluminum fine grid and a silver fine grid sequentially disposed on the silicon substrate; the composite main grid comprises an aluminum main grid and a silver main grid which are sequentially arranged on the silicon substrate.

Optionally, the silver fine grid covers the top surface and the side surface of the aluminum fine grid; and/or the silver main grid covers the top surface and the side surface of the aluminum main grid.

Optionally, the aluminum fine grid is covered by a thickness less than 1/2 of the thickness of the silver fine grid;

and/or the thickness of the aluminum main grid is less than 1/2 of the thickness of the silver main grid.

Optionally, the difference between the width of the silver fine grid and the width of the aluminum fine grid is 5 μm to 20 μm;

and/or the difference between the width of the silver main grid and the width of the aluminum main grid is 5-20 μm.

Optionally, the thickness of the silver fine grid is 5 μm to 10 μm;

and/or the thickness of the silver main grid is 5-10 μm.

Optionally, the conductive contact layer includes a fine gate contact layer, the fine gate contact layer is formed between the aluminum fine gate and the silicon substrate, and the sum of the thicknesses of the aluminum fine gate and the fine gate contact layer is 10 μm to 20 μm;

and/or the conductive contact layer comprises a main grid contact layer, the main grid contact layer is formed between the aluminum main grid and the silicon substrate, and the sum of the thicknesses of the aluminum main grid and the main grid contact layer is 10-20 μm.

Optionally, the conductive contact layer comprises an aluminum doped layer and an aluminum silicon alloy layer.

In a second aspect, the present application provides a solar cell comprising the conductive contact structure of any one of the above solar cells.

In a third aspect, the present application provides a battery module including the solar cell described above.

In a fourth aspect, the present application provides a photovoltaic system including the above-described cell assembly.

The application provides a solar cell and electrically conductive contact structure, battery pack and photovoltaic system thereof owing to adopt electrically conductive contact layer and aluminium silver combined electrode, so can rely on the doping of aluminium grid line self to form ohmic contact, utilize the strong conductivity of silver grid line to derive the electric current effectively. Also, since the aluminum gate line serves as a contact electrode, the thickness of the silver gate line can be made thinner. Thus, the cost can be reduced while the photoelectric conversion efficiency is ensured.

Drawings

Fig. 1 is a schematic structural diagram of a conductive contact structure of a solar cell according to an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a solar cell according to an embodiment of the present application;

FIG. 3 is a schematic structural diagram of a solar cell according to an embodiment of the present application;

FIG. 4 is a schematic illustration of a solar cell according to an embodiment of the present application;

FIG. 5 is a schematic illustration of a solar cell trench according to an embodiment of the present application;

description of the main element symbols:

the solar cell comprises a solar cell 10, a silicon substrate 101, a conductive contact structure 102, a tunneling oxide layer 11, a doped polysilicon layer 12, a first passivation layer 13, a first electrode 14, an aluminum oxide layer 15, a second passivation layer 16, a composite fine gate 17, an aluminum fine gate 171, a silver fine gate 172, a conductive contact layer, an aluminum doped layer 181, an aluminum-silicon alloy layer 182 and a composite main gate 19.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more clearly understood, the present application is 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 of the present application and are not intended to limit the present application.

The cost of the manufacture electrode of the solar cell in the related technology is high, and the ohmic contact can be formed by depending on the doping of the aluminum grid line due to the adoption of the conductive contact layer and the aluminum-silver composite electrode, so that the current can be effectively led out by utilizing the strong conductivity of the silver grid line. Furthermore, since the aluminum grid line serves as a contact electrode, the thickness of the silver grid line can be made thinner. Thus, the cost can be reduced while the photoelectric conversion efficiency is ensured.

Example one

The photovoltaic system of the present embodiment includes the cell assembly of the second embodiment.

According to the photovoltaic system, the conductive contact layer and the aluminum-silver composite electrode are adopted, so that ohmic contact can be formed by doping of the aluminum grid line, and the current can be effectively led out by utilizing the strong conductivity of the silver grid line. Also, since the aluminum gate line serves as a contact electrode, the thickness of the silver gate line can be made thinner. Thus, the cost can be reduced while the photoelectric conversion efficiency is ensured.

In this embodiment, the photovoltaic system can be applied to photovoltaic power stations, such as ground power stations, roof power stations, water surface power stations, etc., and can also be applied to devices or apparatuses that generate electricity by using solar energy, such as user solar power sources, solar street lamps, solar cars, solar buildings, etc. Of course, it is understood that the application scenario of the photovoltaic system is not limited thereto, that is, the photovoltaic system can be applied in all fields requiring solar energy for power generation. Taking a photovoltaic power generation system network as an example, a photovoltaic system may include a photovoltaic array, a combiner box and an inverter, the photovoltaic array may be an array combination of a plurality of battery modules, for example, the plurality of battery modules may constitute a plurality of photovoltaic arrays, the photovoltaic array is connected to the combiner box, the combiner box may combine currents generated by the photovoltaic array, and the combined currents are converted into alternating currents required by a utility grid through the inverter and then are connected to the utility grid to realize solar power supply.

For further explanation and explanation of the embodiment, reference may be made to other parts of the text, and in order to avoid redundancy, further description is omitted here.

Example two

The battery module of the present embodiment includes the solar cell of the third embodiment.

The battery pack of this application embodiment, because electrically conductive contact structure adopts electrically conductive contact layer and aluminium silver combined electrode, so can rely on the doping of aluminium grid line self to form ohmic contact, utilize the strong conductivity of silver grid line to derive the electric current effectively. Also, since the aluminum gate line serves as a contact electrode, the thickness of the silver gate line can be made thinner. Thus, the cost can be reduced while the photoelectric conversion efficiency is ensured.

EXAMPLE III

Referring to fig. 1 and fig. 2, the solar cell 10 of the present embodiment includes the conductive contact structure 102 of the solar cell 10 of any one of the fourth embodiment to the tenth embodiment.

In the solar cell 10 of the embodiment of the present application, the conductive contact structure 102 employs the conductive contact layer and the aluminum-silver composite electrode, so that ohmic contact can be formed by doping the aluminum gate line itself, and the current can be effectively led out by using the strong conductivity of the silver gate line. Furthermore, since the aluminum grid line serves as a contact electrode, the thickness of the silver grid line can be made thinner. Thus, the cost can be reduced while the photoelectric conversion efficiency is ensured.

Specifically, the solar cell 10 includes: the tunneling oxide layer 11, the doped polysilicon layer 12, the first passivation layer 13 and the first electrode 14 are sequentially stacked on the first surface of the silicon substrate 101, the first electrode 14 is a silver electrode, and the first electrode 14 penetrates through the first passivation layer 13 and is in contact with the doped polysilicon; the aluminum oxide layer 15, the second passivation layer 16 and the second electrode are sequentially stacked on the second surface of the silicon substrate 101, the second electrode includes an aluminum electrode, the aluminum oxide layer 15 and the second passivation layer 16 are provided with a slot region, and the second electrode penetrates through the slot region and forms an aluminum doped layer 181 and an aluminum-silicon alloy layer 182 with the silicon substrate 101.

Note that in the present embodiment, the conductive contact structure 102 corresponds to a second electrode. It is understood that in other embodiments, the conductive contact structure 102 may also correspond to the first electrode 14; and may also correspond to the first electrode 14 and the second electrode.

Referring to fig. 2 and 3, specifically, the second electrode is a composite electrode, and the second electrode includes a composite fine grid 17 and a composite main grid 19. The conductive contact layer comprises a fine gate contact layer and a main gate contact layer. The fine gate contact layer 18 includes an aluminum doped layer 181 and an aluminum silicon alloy layer 182. Please note that, the fine gate contact layer 18 is taken as an example for explanation and explanation, and the explanation and explanation of the main gate contact layer may refer to the fine gate contact layer, and are not repeated for avoiding redundancy.

Specifically, the tunnel oxide layer 11 includes one or more of a silicon oxide layer and an aluminum oxide layer. Preferably, the tunnel oxide layer 11 is a silicon oxide layer.

Specifically, the doped polysilicon layer 12 may be a phosphorus-doped single crystal silicon layer with a sheet resistance of <60ohm/squ. In this manner, a smaller number of first electrodes 14 may be used, thereby saving cost.

In particular, the first passivation layer 13 includes a first silicon nitride layer. The second passivation layer 16 includes a second silicon nitride layer. Therefore, the silicon nitride layer is used for antireflection, so that the loss of sunlight can be reduced, the utilization rate of the sunlight is improved, and the photoelectric conversion efficiency is improved. Meanwhile, hydrogen ions can be combined with dangling bonds, recombination centers are reduced, and a passivation effect is achieved. Further, the silicon nitride layer may be one or more layers. In the case where the silicon nitride layers are multilayered, a refractive index gradient may be formed between adjacent two silicon nitride layers. Therefore, gradient extinction is realized through the refractive index gradient, and the utilization rate of sunlight is further improved.

For further explanation and explanation of this embodiment, reference may be made to other parts of the present document, and further explanation is omitted here to avoid redundancy.

Example four

Referring to fig. 1 and fig. 2, the conductive contact structure 102 of the solar cell 10 of the present embodiment includes a conductive contact layer and a composite electrode, the conductive contact layer is disposed between the composite electrode and the silicon substrate 101, the composite electrode includes a composite fine grid 17 and a composite main grid 19, the composite fine grid 17 includes an aluminum fine grid 171 and a silver fine grid 172 sequentially disposed on the silicon substrate 101; the composite main grid 19 includes an aluminum main grid and a silver main grid sequentially provided on the silicon substrate 101.

The conductive contact structure 102 of the solar cell 10 in the embodiment of the present application adopts the conductive contact layer and the aluminum-silver composite electrode, so that ohmic contact can be formed by doping the aluminum grid line itself, and the current can be effectively led out by using the strong conductivity of the silver grid line. Also, since the aluminum gate line serves as a contact electrode, the thickness of the silver gate line can be made thinner. Thus, the cost can be reduced while the photoelectric conversion efficiency is ensured.

Specifically, the silicon substrate 101 is a P-type silicon wafer. Thus, the cost is low. It is understood that in other embodiments, the silicon substrate 101 may also be an N-type silicon wafer.

Specifically, the composite main grid 19 and the composite fine grid 17 are perpendicular to each other. It is understood that in other embodiments, the composite main grid 19 and the composite fine grid 17 may also be at an acute angle.

Specifically, the composite main gate 19 includes a lap region and a non-lap region, and the lap region overlaps with the projection of the composite fine gate 17 on the silicon substrate 101. The lap joint zone is a silver conductor, and the non-lap joint zone comprises an aluminum main grid and a silver main grid which are sequentially stacked. In other words, the silver fine grid is directly connected with the silver conductor in the lap joint area, and the aluminum main grid is not arranged in the lap joint area. Thus, the conductive effect can be improved, and the cost can be reduced.

Specifically, the conductive contact layer includes a fine gate contact layer 18 and a main gate contact layer, the fine gate contact layer 18 is formed between the aluminum fine gate 171 and the silicon substrate 101, and the main gate contact layer is formed between the aluminum main gate and the silicon substrate 101. Only the composite fine gate 17 and the fine gate contact layer 18 are shown in fig. 2. It will be appreciated that the main gate 19 and main gate contact layer are similar and are not shown to avoid redundancy.

Further, the projection of the fine gate contact layer 18 on the silicon substrate 101 overlaps with the projection of the aluminum fine gate 171 on the silicon substrate 101. In this way, the thin gate contact layer 18 is ensured between the aluminum thin gate 171 and the silicon substrate 101, thereby improving the conductive effect.

It is understood that, in other embodiments, the projection of the fine grid contact layer 18 on the silicon substrate 101 may cover and exceed the projection of the aluminum fine grid 171 on the silicon substrate 101, may cover and exceed the projection of the silver fine grid 172 on the silicon substrate 101, may overlap the projection of the silver fine grid 172 on the silicon substrate 101, and may be located within the projection of the silver fine grid 172 on the silicon substrate 101 and outside the projection of the aluminum fine grid 171 on the silicon substrate 101. The positional relationship of the fine grid contact layer 18 with the aluminum fine grid 171 and the silver fine grid 172 is not limited herein.

Further, the projection of the main gate contact layer on the silicon substrate 101 overlaps with the projection of the aluminum main gate on the silicon substrate 101. Therefore, a main grid contact layer is arranged between the aluminum main grid and the silicon substrate 101, and the conductive effect is improved.

It is understood that, in other embodiments, the projection of the main grid contact layer on the silicon substrate 101 may cover and exceed the projection of the aluminum main grid on the silicon substrate 101, may cover and exceed the projection of the silver main grid on the silicon substrate 101, may overlap with the projection of the silver main grid on the silicon substrate 101, may be located within the projection of the silver main grid on the silicon substrate 101 and located outside the projection of the aluminum main grid on the silicon substrate 101. The positional relationship of the main grid contact layer with the aluminum main grid and the silver main grid is not limited herein.

Specifically, the phrase "the composite fine grid 17 includes an aluminum fine grid 171 and a silver fine grid 172 sequentially disposed on the silicon substrate 101" means that the aluminum fine grid 171 is disposed with the silver fine grid 172 on a side away from the silicon substrate 101. In the present embodiment, a part of the silver fine grid 172 is located on a side of the aluminum fine grid 171 facing away from the silicon substrate 101, and contacts the silicon substrate 101 through the aluminum fine grid 171, and the rest directly contacts the silicon substrate 101.

It is understood that in other embodiments, all of the silver fine grids 172 may be located on the side of the aluminum fine grid 171 facing away from the silicon substrate 101, and the silver fine grids 172 do not directly contact with the silicon substrate 101. The contact manner between the silver fine grid 172 and the silicon substrate 101 is not limited herein.

Specifically, the phrase "the composite main grid 19 includes an aluminum main grid and a silver main grid sequentially disposed on the silicon substrate 101" means that a silver main grid is disposed on a side of the aluminum main grid away from the silicon substrate 101. In this embodiment, a part of the silver main gate is located on a side of the aluminum main gate away from the silicon substrate 101, and contacts the silicon substrate 101 through the aluminum main gate, and the rest directly contacts the silicon substrate 101.

It is understood that in other embodiments, all of the silver main gate may be located on a side of the aluminum main gate facing away from the silicon substrate 101, and the silver main gate does not directly contact a portion of the silicon substrate 101. The contact manner between the silver main gate and the silicon substrate 101 is not limited here.

Specifically, the aluminum fine grid 171, the silver fine grid 172, the aluminum main grid and the silver main grid can be made by screen printing and high-temperature sintering. Therefore, the efficiency and the precision of manufacturing the composite electrode are higher, and the quality of the battery is favorably improved. In other embodiments, the composite electrode may be formed by sputtering, vacuum evaporation, or the like.

Specifically, the silicon substrate 101 may be further laminated with a film layer, for example, an aluminum oxide layer 15 and a second passivation layer 16 in sequence. The film is formed with a grooved region through which the aluminum fine grid 171 contacts the conductive contact layer. In the case where the grooved region is continuous, the aluminum fine grid 171 may be continuous. In the case where the groove region is discontinuous, the aluminum fine grid 171 may be continuous, and a plurality of discontinuous groove regions may be connected into one strip.

Specifically, a fine silver grid 172 may be provided in the grooved region, as shown in fig. 1 and 2. In other embodiments, the silver fine grid 172 may also be disposed on a side of the film layer facing away from the silicon substrate 101. That is, the silver fine grid 172 does not burn through the second passivation layer 16.

Referring to fig. 3 and 4, in particular, a laser may be used to open a dot-shaped hole in a film layer stacked on a silicon substrate 101. The point-shaped holes are circular. Further, the diameter D of the dot-shaped holes is 25 μm to 45 μm. For example, 25 μm, 27 μm, 30 μm, 32 μm, 35 μm, 40 μm, and 45 μm. Further, the pitch d1 between the dot-shaped holes adjacent in the length direction of the fine grid 17 is 400 μm to 800 μm. For example, 400 μm, 420 μm, 500 μm, 600 μm, 700 μm, 780 μm, 800 μm. Further, the pitch d2 between the dot-like holes adjacent in the width direction of the fine gate 17 is 500 μm to 1000 μm. For example, 500. Mu.m, 520. Mu.m, 600. Mu.m, 800. Mu.m, 980. Mu.m, 1000. Mu.m.

Referring to fig. 5, in particular, a laser may be used to form a discontinuous linear groove in a film layer stacked on a silicon substrate 101. The linear grooves are interrupted and rectangular. Further, the length L1 of the linear groove is 0.1mm to 0.5mm. For example, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm. Further, the width L2 of the linear groove is 25 μm to 45 μm. For example, 25 μm, 28 μm, 30 μm, 35 μm, 38 μm, 40 μm, and 45 μm. Further, the pitch d3 between the linear grooves adjacent in the longitudinal direction of the fine grid 17 is 0.2mm to 1mm. For example, 0.2mm, 0.4mm, 0.8mm, 1mm. Further, the pitch d4 between the linear grooves adjacent in the width direction of the fine grid 17 is 0.5mm to 1mm. For example, 0.5mm, 0.6mm, 0.8mm, 1mm.

Specifically, a continuous linear groove may be formed in a film layer stacked over the silicon substrate 101 by a laser.

Specifically, an aluminum main grid may contact the conductive contact layer through a grooved region, and a silver main grid may be provided in the grooved region, as shown in fig. 1 and 2. In other embodiments, the silver main gate may also be provided on the side of the film layer facing away from the silicon substrate 101, i.e. the silver main gate does not burn through the second passivation layer 16. For the explanation and explanation of this part, reference is made to the foregoing description, and redundant description is omitted here. It is to be understood that the aluminum main gate and the silver main gate may also be provided not in the trenched region but on the side of the second passivation layer 16 facing away from the silicon substrate 101.

Alternatively, the silicon substrate 101 under the trench region forms a recess region 1011, the second electrode 17 passes through the trench region, an aluminum doped layer 181 is formed on the surface of the recess region 1011 and an aluminum-silicon alloy layer 182 is filled in the recess region 1011.

Alternatively, the aluminum fine grid 171 is 30 μm-80 μm wide. For example, 30 μm, 40 μm, 50 μm, 70 μm, 80 μm. In this way, the width of the aluminum fine grid 171 is in a suitable range, which is beneficial to efficiently leading out the current.

Optionally, the width of the invaginated region 1011 is greater than the width of the grooved region. Optionally, the width of the aluminum-silicon alloy layer 182 is greater than the width of the trenched region, and the aluminum-silicon alloy layer 182 is locally covered with the second passivation layer 16. Thus, a larger invagination region 1011 can be formed by a narrower slotting region, so that the contact area of the aluminum doping layer 181 and the silicon wafer is larger, the contact area of the aluminum doping layer 181 and the aluminum-silicon alloy layer 182 is larger, the expanded electrode and the surface contact resistance of the body region can be reduced, and the contradiction between the light shielding area of the electrode and the resistance is relieved.

Alternatively, the ratio of the surface area of the invaginated region 1011 to the projected area in the thickness direction is greater than 1.05. Thus, the recessed region 1011 is made larger, the contact area between the aluminum doped layer 181 and the silicon wafer is made larger, the contact area between the aluminum doped layer 181 and the aluminum-silicon alloy layer 182 is made larger, the extended electrode and the surface contact resistance of the body region can be reduced, and the contradiction between the light shielding area of the electrode and the resistance is relieved.

Optionally, the invagination region 1011 has an invagination depth of greater than 3 μm. For example, 3 μm, 4 μm, 5 μm, and 6 μm. Thus, the surface area of the invaginated region 1011 is increased by making the invagination depth larger.

For further explanation and description of this embodiment, reference may be made to other parts of this document, especially to embodiment one, and further description is omitted here to avoid redundancy.

EXAMPLE five

Referring to fig. 1, in some alternative embodiments, silver fine grid 172 covers the top and side surfaces of aluminum fine grid 171. In this way, the contact area between the silver fine grid 172 and the aluminum fine grid 171 is large, so that the electric conduction effect between the silver fine grid 172 and the aluminum fine grid 171 is better.

It is understood that in other embodiments, the silver fine grid 172 may cover only the top surface of the aluminum fine grid 171, and not the side surface of the aluminum fine grid 171; the silver fine grids 172 may cover only the side surfaces of the aluminum fine grids 171 without covering the top surfaces of the aluminum fine grids 171.

Specifically, the silver fine grid 172 entirely covers the top surface of the aluminum fine grid 171, and entirely covers the side surfaces of the aluminum fine grid 171. In this way, the contact area between the silver fine grids 172 and the aluminum fine grids 171 is made larger, so that the electric conduction effect between the silver fine grids 172 and the aluminum fine grids 171 is better.

It is understood that in other embodiments, the silver fine grid 172 may cover a partial area of the top surface of the aluminum fine grid 171; the silver fine grid 172 may cover a partial area of the side surface of the aluminum fine grid 171. For example, the silver fine grid 172 may form a hollowed-out region.

In some alternative embodiments, the silver main grid covers the top and side surfaces of the aluminum main grid. Therefore, the contact area between the silver main grid and the aluminum main grid is larger, so that the conductive effect between the silver main grid and the aluminum main grid is better.

It is understood that in other embodiments, the silver main grid may cover only the top surface of the aluminum main grid, and not the side surface of the aluminum main grid; the silver main grid does not cover the top surface of the aluminum main grid, and only covers the side surface of the aluminum main grid.

Specifically, the silver main grid covers the top surface of the aluminum main grid on the whole surface, and covers the side surface of the aluminum main grid on the whole surface. Therefore, the contact area between the silver main grid and the aluminum main grid is larger, and the conductive effect between the silver main grid and the aluminum main grid is better.

It is understood that in other embodiments, the silver main grid may cover a partial area of the top surface of the aluminum main grid; the silver main grid can also cover partial areas of the side surfaces of the aluminum main grid. For example, the silver master grid may form a hollowed-out region.

EXAMPLE six

In some alternative embodiments, the aluminum fine grid 171 is covered to a thickness less than 1/2 of the thickness of the silver fine grid 172. The aluminum fine grid 171 is covered to a thickness of, for example, 1/3, 1/4, 1/5, 1/6 of the thickness of the silver fine grid 172. Therefore, the thickness ratio of the silver fine grid 172 to the aluminum fine grid 171 is in a proper range, so that poor overall conductivity caused by too small thickness ratio can be avoided, and too high cost caused by too large thickness ratio can also be avoided.

In some alternative embodiments, the aluminum primary grid is covered to a thickness less than 1/2 of the thickness of the silver primary grid. The aluminum primary grid is covered to a thickness of, for example, 1/3, 1/4, 1/5, 1/6 of the thickness of the silver primary grid. Therefore, the thickness ratio of the silver main grid to the aluminum main grid is in a proper range, poor overall conductivity caused by too small thickness ratio can be avoided, and too high cost caused by too large thickness ratio can also be avoided.

EXAMPLE seven

In some alternative embodiments, the difference between the width of the silver fine grid 172 and the width of the aluminum fine grid 171 is 5 μm to 20 μm. For example, 5 μm, 6 μm, 10 μm, 15 μm, 20 μm. Therefore, the difference between the width of the silver fine grid 172 and the width of the aluminum fine grid 171 is within a proper range, the situation that the silver fine grid 172 covered on the side surface of the aluminum fine grid 171 is thin due to too small width difference can be avoided, the situation that the conductive effect is poor is avoided, the situation that the silver fine grid 172 covered on the side surface of the aluminum fine grid 171 is thick due to too large width difference can be avoided, and the situation that the cost is high is avoided.

Note that in the present embodiment, the width of the silver fine grid 172 is greater than the width of the aluminum fine grid 171. In this way, the silver fine grid 172 is allowed to cover the rate fine grid 17 in the width direction, thereby improving the conductive effect.

In some alternative embodiments, the difference between the width of the silver main grid and the width of the aluminum main grid is 5 μm to 20 μm. For example, 5 μm, 6 μm, 10 μm, 15 μm, 20 μm. So for the width of silver main grid and the width difference of aluminium main grid are in suitable scope, can avoid the silver main grid that the aluminium main grid side that the poor undersize of width leads to covers thinner, thereby avoid electrically conductive effect relatively poor, can avoid the silver main grid that the aluminium main grid side that the poor oversize of width leads to covers thicker, thereby avoid the cost higher.

Note that in this embodiment, the width of the silver main gate is greater than that of the aluminum main gate. Therefore, the silver main grid can cover the aluminum main grid in the width direction, and the conductive effect is improved.

Example eight

In some alternative embodiments, the silver fine grid 172 has a thickness of 5 μm to 10 μm. For example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm. Therefore, the thickness of the silver fine grid 172 is in a proper range, poor conducting effect caused by too small thickness of the silver fine grid 172 can be avoided, and high cost caused by too large thickness of the silver fine grid 172 can also be avoided.

In some alternative embodiments, the silver master grid has a thickness of 5 μm to 10 μm. For example, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm. Therefore, the thickness of the silver main grid is in a proper range, poor conducting effect caused by over-small thickness of the silver main grid can be avoided, and high cost caused by over-large thickness of the silver main grid can also be avoided.

Example nine

In some alternative embodiments, the conductive contact layer comprises a fine gate contact layer 18, the fine gate contact layer 18 is formed between the aluminum fine gate 171 and the silicon substrate 101, and the sum of the thicknesses of the aluminum fine gate 171 and the fine gate contact layer 18 is 10 μm-20 μm. For example, 10 μm, 11 μm, 15 μm, 18 μm, 19 μm, 20 μm. Therefore, the sum of the thicknesses is in a proper range, so that the ohmic contact formed by self-doping of the aluminum fine grid 171 is better, and the current is led out efficiently.

In some alternative embodiments, the conductive contact layer comprises a main gate contact layer formed between the aluminum main gate and the silicon substrate 101, and the sum of the thicknesses of the aluminum main gate and the main gate contact layer is 10 μm to 20 μm. For example, 10 μm, 11 μm, 15 μm, 18 μm, 19 μm, 20 μm. Therefore, the sum of the thicknesses is in a proper range, so that the ohmic contact formed by the self-doping of the aluminum main gate is better, and the current is led out efficiently.

Example ten

In some alternative embodiments, the conductive contact layer comprises an aluminum doped layer 181 and an aluminum silicon alloy layer 182. Specifically, the aluminum doped layer 181 is an aluminum doped single crystal silicon layer, and forms a P + surface field. An aluminum silicon alloy layer 182 is located between the aluminum doped layer 181 and the composite electrode. In this way, the contact of the P + surface field with the composite electrode is achieved through the aluminum-silicon alloy layer 182.

Specifically, an aluminum doped layer 181 is formed on the surface of the recess region 1011, and the aluminum-silicon alloy layer 182 fills the recess region 1011. Thus, the contact area between the aluminum doped layer 181 and the aluminum-silicon alloy layer 182 can be effectively increased, and the extended electrode and the surface contact resistance of the body region can be reduced, thereby alleviating the contradiction between the light shielding area of the electrode and the resistance.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed. Furthermore, the particular features, structures, materials, or characteristics described in connection with the embodiments or examples disclosed herein may be combined in any suitable manner in any one or more of the embodiments or examples.

Claims

1. The conductive contact structure of the solar cell is characterized by comprising a conductive contact layer and a composite electrode, wherein the conductive contact layer is arranged between the composite electrode and a silicon substrate; the composite main grid comprises an aluminum main grid and a silver main grid which are sequentially arranged on the silicon substrate.

2. The conductive contact structure of a solar cell according to claim 1, wherein the silver fine grid covers a top surface and a side surface of the aluminum fine grid; and/or the silver main grid covers the top surface and the side surface of the aluminum main grid.

3. The conductive contact structure of a solar cell according to claim 2, wherein the aluminum fine grid is covered to a thickness of less than 1/2 of the thickness of the silver fine grid;

and/or the aluminum main grid is covered by the thickness of less than 1/2 of the thickness of the silver main grid.

4. The conductive contact structure of a solar cell according to claim 1, wherein the difference between the width of the silver fine grid and the width of the aluminum fine grid is 5 μm to 20 μm;

5. The conductive contact structure of a solar cell according to claim 1, wherein the silver fine grid has a thickness of 5 μm to 10 μm;

and/or the thickness of the silver main grid is 5-10 μm.

6. The conductive contact structure of a solar cell according to claim 1, wherein the conductive contact layer comprises a fine-grid contact layer formed between the aluminum fine grid and the silicon substrate, and the sum of the thicknesses of the aluminum fine grid and the fine-grid contact layer is 10 μm to 20 μm;

and/or the conductive contact layer comprises a main gate contact layer, the main gate contact layer is formed between the aluminum main gate and the silicon substrate, and the sum of the thicknesses of the aluminum main gate and the main gate contact layer is 10-20 μm.

7. The conductive contact structure of a solar cell of claim 1, wherein the conductive contact layer comprises an aluminum doped layer and an aluminum silicon alloy layer.

8. A solar cell comprising the conductive contact structure of the solar cell of any one of claims 1-7.

9. A battery module comprising the solar cell of claim 8.

10. A photovoltaic system comprising the cell assembly of claim 9.