CN118380481B - Solar cell - Google Patents

Abstract

The invention is applicable to the technical field of photovoltaics, and provides a solar cell, wherein at least one surface of the solar cell comprises a plurality of repeated areas, each repeated area comprises a plurality of PNG units, each PNG unit comprises an N area, a P area and a G area, at least any two PNG units are respectively a first unit and a second unit, and the first unit and the second unit meet at least one of the following conditions: the widths of the P areas are different; the widths of the N areas are different; the width of the G region is not the same. The width difference of the N area and the P area is adjusted, so that the light absorption range and the photoelectric conversion efficiency of the solar cell can be improved, the light energy resource is utilized to the greatest extent, and the collection probability of the photo-generated current is greatly increased while the productivity is not influenced; and the efficiency change ratio of the battery to the component and the yield of the battery piece and the component are improved.

Description

A solar cell

Technical Field

The invention belongs to the technical field of photovoltaics, and in particular relates to a solar cell.

Background Art

The back junction cell uses photolithography technology to diffuse phosphorus and boron locally on the back of the cell, forming a P region and N region with finger-like cross arrangement, as well as a P+ region and n+ region above them. The P+ and N+ regions formed by heavy expansion can effectively eliminate the voltage saturation effect under high concentration conditions. In addition, the coverage area of the P+ and N+ region contact electrodes almost reaches 1/2 of the back surface, greatly reducing the series resistance. A G region is set between the P region and the N region to form a gap, which improves the separation efficiency of photogenerated charges and reduces recombination losses.

At present, the fine grid area of the back junction battery usually uses a single PNG structure, but different areas of the battery cell (such as the edges) have different carrier collection capabilities. Therefore, the existing battery cell structure cannot maximize the carrier collection and has low collection efficiency.

Summary of the invention

The present invention provides a solar cell, aiming to solve the problem that the battery structure cannot realize the maximization of carrier collection and the collection efficiency is low.

The present invention is implemented as follows: a solar cell, wherein at least one side of the solar cell includes a plurality of repeated regions, the repeated regions include a plurality of PNG units, the PNG units include an N region, a P region, and a G region, wherein at least any two of the PNG units are respectively a first unit and a second unit, and the first unit and the second unit satisfy at least one of the following:

The width of the P region is different;

The width of the N region is different;

The width of the G area is different.

Optionally, the P region widths and/or N region widths of the first unit and the second unit are different, and the G region widths of the first unit and the second unit are the same.

Optionally, each of the repeating regions includes one first unit and at least three second units.

Optionally, the total width of the first unit is 1 to 3 times the total width of the second unit.

Optionally, the width of the P region in the first unit is 0.3 to 3 times the width of the P region in the second unit; the width of the N region in the first unit is 0.3 to 3 times the width of the N region in the second unit.

Optionally, a width ratio of the N region to the P region in each of the PNG units is 2:8 to 8:2.

Optionally, G regions are respectively arranged on both sides adjacent to the N region.

Optionally, in each of the PNG units, metal gate lines are respectively arranged in the P region and the N region, and a distance between the metal gate line and the adjacent G region is greater than 0.

Optionally, the width of the metal gate line in the P region in the first unit and the width of the metal gate line in the P region in the second unit are in a ratio of 0.05:20; the width of the metal gate line in the N region in the first unit and the width of the metal gate line in the N region in the second unit are in a ratio of 0.05:20.

Optionally, the distance between the metal gate line and the adjacent G region is not less than 25 μm.

The beneficial effects achieved by the present invention are that at least one side of the solar cell includes multiple repeated areas, each repeated area includes at least two PNG units, and each PNG unit includes an N region, a P region, and a G region. In this design, any two PNG units are defined as a first unit and a second unit, respectively, and at least one of the width of the P region, the width of the N region, and the width of the G region of the first unit and the second unit may be different. By adjusting the width difference of the N region, the P region, and the G region, the light absorption range and the photoelectric conversion efficiency of the solar cell can be improved, and the light energy resources can be utilized to the greatest extent, and the probability of collecting photocurrent can be greatly increased without affecting the production capacity; the efficiency change ratio from battery to module and the yield of battery cells and modules can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of a repeated region of a first solar cell provided by the present invention;

FIG2 is a schematic structural diagram of a second type of repeated region of a solar cell provided by the present invention;

FIG3 is a schematic structural diagram of a repeated region of a third solar cell provided by the present invention;

FIG4 is a schematic structural diagram of a repeating region of a fourth solar cell provided by the present invention;

FIG. 5 is a schematic structural diagram of the repeated region of the fifth solar cell provided by the present invention.

Description of reference numerals:

100, repeated region; 101, first unit; 102, second unit.

DETAILED DESCRIPTION

In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and/or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and/or settings discussed. In addition, the examples of various specific processes and materials provided by the present invention, but those of ordinary skill in the art can be aware of the application of other processes and/or the use of other materials.

In the present invention, at least one side of the solar cell includes multiple repeated areas, each repeated area includes at least two PNG units, and each PNG unit includes an N region, a P region, and a G region. In this design, any two PNG units are defined as a first unit and a second unit, respectively, and at least one of the width of the P region, the width of the N region, and the width of the G region of the first unit and the second unit may be different. By adjusting the width difference of the N region, the P region, and the G region, the light absorption range and photoelectric conversion efficiency of the solar cell can be improved, and the light energy resources can be utilized to the greatest extent, and the probability of collecting photocurrent can be greatly increased without affecting the production capacity; the efficiency change ratio from battery to module and the yield of battery cells and modules can be improved.

Embodiment 1

This embodiment provides a solar cell, wherein at least one side of the solar cell includes a plurality of repeated regions 100, the repeated regions 100 include a plurality of PNG units, the PNG units include an N region, a P region, and a G region, wherein at least any two of the PNG units are a first unit 101 and a second unit 102, respectively, and the first unit 101 and the second unit 102 satisfy at least one of the following conditions:

The width of the P region is different;

The width of the N region is different;

The width of the G area is different.

A plurality of repeating regions 100 are arranged on one or both sides of the solar cell panel, each repeating region 100 includes two or more PNG units, the PNG units included in each repeating region 100 are the same as the PNG units included in other repeating regions 100, and a plurality of identical repeating regions 100 are arranged repeatedly. It can be understood that the repeating region 100 does not have to cover the entire cell sheet, and a portion of the cell sheet may not be composed of the repeating region 100.

Each PNG unit includes an N region, a P region and a G region. The N region is called N-type semiconductor region in full in English, which can be an N-type doped region formed by diffusion doping, an N-type silicon substrate, or an N+ region formed by ion implantation or other methods; the P region is called P-type semiconductor in full in English, which can be a P-type doped region formed by diffusion doping, a P-type silicon substrate, a P+ aluminum back field formed by sintering of aluminum paste, or a P+ region formed by ion implantation or other methods; the G region is the GAP region, also known as the photogenerated charge separation layer, which can be an undoped silicon-based region, a shallowly doped region or other electrically poor conductor structures. It is located between the P region and the N region in order to achieve the spatial separation of the PN junction and effectively solve the problem of leakage in the P and N contact regions.

Any two PNG units are respectively a first unit 101 and a second unit 102, and the first unit 101 and the second unit 102 are arranged adjacent to each other. Specifically, the widths of the P regions of the first unit 101 and the second unit 102 may be different, but the widths of the N regions may be the same, as shown in FIG1 ; the widths of the N regions of the first unit 101 and the second unit 102 may be different, but the widths of the P regions may be the same, as shown in FIG2 ; the widths of the P regions and the N regions of the first unit 101 and the second unit 102 may be different, but the widths of the P region and the N region in the first unit 101 may be the same, and the widths of the P region and the N region in the second unit 102 may be different, as shown in FIG3 ; the widths of the P regions and the N regions of the first unit 101 and the second unit 102 may be different, but the widths of the P region and the N region in the second unit 102 may be the same, and the widths of the P region and the N region in the first unit 101 may be different, as shown in FIG4 ; the widths of the P regions and the N regions of the first unit 101 and the second unit 102 may be different, and the widths of the P region and the N region in the first unit 101 may be the same, and the widths of the P region and the N region in the second unit 102 may be the same, as shown in FIG5 . The above examples also include two cases where the widths of the P regions of the first unit 101 and the second unit 102 are the same or different.

Specifically, the N region, P region and G region in the PNG unit may be laid out on the same plane, or the N region, P region and G region may be partially overlapped.

In this embodiment, this solar cell can be realized by using different materials and processes. By precisely controlling the width of the N region, the P region, and the G region, the charge separation efficiency and power output performance of the solar cell under different lighting conditions can be adjusted. For example, the charge transfer and power collection effect can be optimized by controlling the width of the P region to improve the photoelectric conversion efficiency of the battery. In addition, by adjusting the width difference of the N region, the P region, and the G region, the light absorption range and photoelectric conversion efficiency of the solar cell can be improved, and the light energy resources can be utilized to the greatest extent. The probability of collecting photocurrent is greatly increased without affecting the production capacity; the efficiency change ratio from battery to module and the yield of battery cells and modules are improved.

During the manufacturing process, advanced process technologies such as photolithography and chemical deposition can be used to accurately define and control the structural dimensions of the N region, P region, and G region. At the same time, material selection is also crucial, and high-efficiency photovoltaic materials such as silicon, cadmium selenide or gallium arsenide can be used to achieve higher photoelectric conversion efficiency.

It is important to understand that this design can optimize the performance of solar cells and improve their stability and flexibility when light conditions change. By adjusting the widths of the N, P, and G regions, it is possible to fine-tune the cell characteristics to meet the requirements of different application scenarios. In the photovoltaic field, this design can provide new ideas and possibilities for the research and development of solar cells, and help promote the advancement and application of solar photovoltaic technology.

Embodiment 2

Based on the first embodiment, the P region widths of the first unit 101 and the N region widths of the second unit 102 are different, and the G region widths of the first unit 101 and the second unit 102 are the same.

The width of the G zone is an important parameter in solar cells. A narrower G zone can promote the rapid separation of photogenerated charges and prevent charge recombination. Therefore, a smaller G zone width helps to improve the photoelectric conversion efficiency of the battery. However, it will increase resistance and affect the current collection effect.

Keeping the width of each G region equal can ensure the uniformity and consistency of the battery structure, help control and optimize the performance of the battery during the production process, and reduce the uneven effects in different areas. Having G regions of the same width can simplify the manufacturing process, without the need for additional process steps to adjust the size of different areas, making it easier to arrange the battery cells, which is conducive to improving production efficiency and reducing production costs.

Embodiment 3

Based on the first embodiment, each of the repeating regions 100 includes a first unit 101 and at least three second units 102 .

In the simulation experiment of photovoltaic cells, it was found that the theoretical efficiency of a PNG unit with a width of 1.2mm was 26.914%, and the theoretical efficiency of a PNG unit with a width of 0.8mm was 27.132%. By combining three 0.8mm and one 1.2mm, the efficiency was 27.088%, with an efficiency reduction of <0.05%. The efficiency loss is small, but it can greatly improve the battery cell yield.

The actual efficiency of the PNG unit can be estimated by the following formula:

Assuming that the two PNG elements are pitch1 and pitch2, the theoretical photoelectric conversion efficiency of the PNG element with pitch1 width w ₁ is: Eta ₁ ;

The theoretical photoelectric conversion efficiency of the PNG unit with a pitch2 width of w ₂ is: Eta ₂ ;

When the minimum repeat area 100 contains n ₁ Pitch 1s and n ₂ Pitch 2s, its efficiency can be estimated as the arithmetic mean Eta = (n ₁ × w ₁ × Eta ₁ + n ₂ × w ₂ × Eta ₁ ) / (n ₁ × w ₁ + n ₂ × w ₂ ). The process suitable for production can be inferred based on the calculated efficiency value and yield value. If the expected efficiency value is Eta ₁ , the structure with (Eta-Eta ₁ ) < 0.05% is selected for design.

According to experimental data, when the ratio of the number of the first unit 101 to the second unit 102 in the repeating area 100 is greater than 1:3, the impact on efficiency is small, and the improvement effect on the electrical yield of the battery cell is obvious. Specifically, the ratio of the number can be calculated according to actual needs using the above calculation formula.

Embodiment 4

Based on the first embodiment, the total width of the first unit 101 is 1 to 3 times the total width of the second unit 102 .

In the simulation experiment of photovoltaic cells, it was found that the theoretical efficiency of a PNG unit with a width of 0.4mm is 27.23%. If a combination of a PNG unit with a width of 0.4mm and a PNG unit with a width of 1.3mm is used, the efficiency is 27.01%, and the efficiency reduction value is 0.22%. The efficiency loss is too large to meet the requirements of improving battery design efficiency.

Specifically, the total width of the first unit 101 may be greater than the total width of the second unit 102 . Laboratory verification shows that when the total width of the first unit 101 is not greater than three times the total width of the second unit 102 , the impact on the cell efficiency is small.

The total width of the first unit 101 may be the same as the total width of the second unit 102. Specifically, the width of the N region of the first unit 101 is consistent with the width of the P region of the second unit 102, and the width of the N region of the second unit 102 is consistent with the width of the P region of the first unit 101. The specific width can be set according to actual usage requirements.

Embodiment 5

Based on the first embodiment, based on the first embodiment, the width of the P region in the first unit 101 is 0.3 to 3 times the width of the P region in the second unit 102; the width of the N region in the first unit 101 is 0.3 to 3 times the width of the N region in the second unit 102.

The width of the P region in the first cell 101 may be smaller than the width of the P region in the second cell 102, for example, the width of the P region in the first cell 101 is 0.3 times the width of the P region in the second cell 102; the width of the P region in the first cell 101 may be larger than the width of the P region in the second cell 102, for example, the width of the P region in the first cell 101 is 3 times the width of the P region in the second cell 102. According to laboratory data, when the width of the P region in the first cell 101 is 0.3 to 3 times the width of the P region in the second cell 102, the impact on the battery efficiency is small and the battery appearance is more beautiful.

The width of the N region in the first cell 101 may be smaller than the width of the N region in the second cell 102, for example, the width of the N region in the first cell 101 is 0.3 times the width of the N region in the second cell 102; the width of the N region in the first cell 101 may be larger than the width of the N region in the second cell 102, for example, the width of the N region in the first cell 101 is 3 times the width of the N region in the second cell 102. According to laboratory data, when the width of the N region in the first cell 101 is 0.3 to 3 times the width of the N region in the second cell 102, the impact on battery efficiency is small and the battery appearance is more beautiful.

The ratio of the width of the P region in the first unit 101 to the width of the P region in the second unit 102, and the ratio of the width of the N region in the first unit 101 to the width of the N region in the second unit 102 can be set according to actual usage requirements.

Embodiment 6

Based on the first embodiment, the width ratio of the N region to the P region in each PNG unit is 2:8 to 8:2.

In the simulation experiment of photovoltaic cells, it was found that for a pitch unit with a width of 1.2mm, when the width ratio of the P region and the N region is 1:1, its efficiency is 26.95%; when the width ratio of the P region and the N region is 1:5, its efficiency is 26.63%, and the efficiency reduction value is 0.32%. The efficiency loss is too large to meet the needs of improving the efficiency of battery design; when the width ratio of the P region and the N region is 5:1, its efficiency is 26.71%, and the efficiency reduction value is 0.24%. The efficiency loss is too large to meet the needs of improving the efficiency of battery design.

According to laboratory data, when the width ratio of the N region and the P region in each pitch unit is 2:8 to 8:2, the impact on battery efficiency is small and the battery appearance is more beautiful.

Specifically, in a PNG unit, the width of the N region may be greater than the width of the P region, for example, the ratio of the width of the N region to the width of the P region may be 6:4; the width of the N region may also be equal to the width of the P region, for example, the ratio of the width of the N region to the width of the P region may be 1:1; the width of the N region may also be smaller than the width of the P region, for example, the ratio of the width of the N region to the width of the P region may be 4:6.

Embodiment 7

On the basis of the first embodiment, G regions are respectively arranged on both sides of the N region.

The G area is set to form a gap between the P area and the N area. In the same PNG unit, the G area is set between the P area and the N area, and in adjacent PNG units, the N area of the previous unit is adjacent to the P area of the next unit. G areas are set on both sides of the adjacent N area to ensure that any adjacent P area and N area are separated by G areas.

Embodiment 8

On the basis of the first embodiment, in each of the PNG units, metal gate lines are respectively arranged in the P region and the N region, and the distance between the metal gate line and the adjacent G region is greater than zero.

The metal gate line is set in the P region and the N region. The metal gate line is a conductor used to carry current and conducts current by contacting the P region or the N region.

In a specific embodiment, the design details of the solar cell structure are extremely important. For the P region and N region in each PNG unit, the setting of the metal grid line can not only improve the conductivity of the electrical node, but also effectively collect and conduct photogenerated charges. The material of the metal grid line can be selected from metals such as silver, aluminum, copper, etc. with excellent conductivity and strong antioxidant ability to ensure long-term stable electrical performance and resistance to environmental corrosion.

Furthermore, the metal gate lines are respectively arranged in the middle of the P region and the N region and keep a certain distance, which is not only to maintain the independence of electrical performance, but also to prevent the occurrence of electrical faults such as short circuits. It should be understood that this layout design can be achieved through precise lithography and deposition technology to ensure that the position and distance of each metal gate line can meet the design requirements. These processes can be achieved through high-precision PLC control devices to ensure the manufacturing accuracy of each PNG unit.

In addition, in practical applications, the metal grid lines corresponding to the P and N regions must not only have good conductivity, but also have certain mechanical strength and flexibility to adapt to various operations during the production and installation of solar cells. It is understandable that the selection of appropriate metal materials and structural design is particularly critical, which is also a necessary condition for improving the overall performance and reliability of the battery.

In actual operation, the distance between the metal grid line in the P region and the adjacent G region is kept greater than 0. This can not only effectively avoid the recombination loss of photogenerated carriers in the battery structure and increase the current collection efficiency, but also reduce internal stress concentration, thereby improving the mechanical stability of the battery.

Through the detailed design of this embodiment, the solar cell can be optimized in terms of photoelectric conversion efficiency, long-term reliability, environmental adaptability, etc. This structural design not only improves the working stability and current collection efficiency of the solar cell, but also provides a reliable technical reference and design theory for the future development of more efficient solar cells.

In one embodiment, the distance between the metal gate line and the adjacent G region is greater than or equal to 25 μm. 25 μm is a safe distance to prevent the metal line from being arranged in the G region and being unable to conduct current.

Embodiment 9

Based on the eighth embodiment, the width of the metal gate line in the P region of the first unit 101 and the width of the metal gate line in the P region of the second unit 102 are in a ratio of 0.05:20; the width of the metal gate line in the N region of the first unit 101 and the width of the metal gate line in the N region of the second unit 102 are in a ratio of 0.05:20.

In this embodiment, the proportional relationship between the metal grid line widths of different units in the solar cell is further described. Specifically, the ratio of the metal grid line width in the P region of the first unit 101 to the metal grid line width in the P region of the second unit 102 is 0.05:20; similarly, the ratio of the metal grid line width in the N region of the first unit 101 to the metal grid line width in the N region of the second unit 102 is also 0.05:20. This design detail can be understood as optimizing the overall performance of the solar cell by changing the metal grid line widths of different units.

The advantage is that by designing metal grid lines of different widths between the first unit 101 and the second unit 102 , the current collection path can be optimized and the charge carrier collection efficiency can be improved.

Narrower metal grid lines have a higher density in a specific area, improving the current collection capacity of a small area. Setting metal grid lines of different widths may help reduce the overall circuit resistance, thereby reducing power loss and increasing output power. Metal grid lines of different widths can help disperse the heat generated in the battery and avoid the occurrence of overheating areas, thereby improving stability and service life. High-precision photolithography technology and metal deposition technology are used to accurately control and manufacture metal grid lines of different widths to meet specific ratio requirements. Metal materials (such as silver, aluminum or copper) with high conductivity, corrosion resistance and suitable mechanical properties are selected to make metal grid lines.

Specifically, the width of the metal gate lines in the P and N regions of the first unit 101: For example, the metal gate lines in the P and N regions of the first unit 101 may be set to a minimum width, such as 10 μm. Compared with the first unit 101, the width of the metal gate lines in the P and N regions of the second unit 102 is 20 times that of the first unit 101, i.e., 200 μm.

Through the above design, the overall performance of solar cells can be more balanced, efficient and stable. This design helps to adapt to the electrical performance requirements under different light intensities and different installation conditions. This will form a significant width difference between different units, thus affecting the current collection efficiency and resistance characteristics.

In summary, the solar cell designed by controlling the ratio of the metal grid widths in the first and second units 102 can significantly improve the overall photoelectric conversion efficiency, optimize thermal management and current collection routes, and provide strong technical advantages for commercial applications.

The above description is only a preferred embodiment of the present invention and is 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 in the protection scope of the present invention.

Claims (8)

1. A solar cell, characterized in that at least one side of the solar cell includes a plurality of overlapping regions, the overlapping regions include a plurality of PNG units, the PNG units include an N region, a P region and a G region, and the G regions are respectively arranged on both adjacent sides of the N region; at least any two of the PNG units are respectively a first unit and a second unit, and the first unit and the second unit satisfy at least one of the following: The width of the P region is different; The width of the N region is different; The width of the G area is different; The total width of the first unit is greater than the total width of the second unit, and each of the repeating regions includes one first unit and at least three second units. 2 . The solar cell according to claim 1 , wherein the P region widths and/or the N region widths of the first unit and the second unit are different, and the G region widths of the first unit and the second unit are the same. 3 . The solar cell according to claim 1 , wherein a total width of the first unit is 1 to 3 times a total width of the second unit. 4. The solar cell according to claim 1, wherein the width of the P region in the first unit is 0.3 to 3 times the width of the P region in the second unit; the width of the N region in the first unit is 0.3 to 3 times the width of the N region in the second unit. 5 . The solar cell according to claim 1 , wherein a width ratio of the N region to the P region in each of the PNG units is 2:8 to 8:2. 6 . The solar cell according to claim 1 , wherein in each of the PNG units, metal grid lines are respectively arranged in the P region and the N region, and a distance between the metal grid lines and the adjacent G region is greater than 0. 7. The solar cell as described in claim 6 is characterized in that the width of the metal grid line in the P region in the first unit and the width of the metal grid line in the P region in the second unit are in a ratio of 0.05:20; the width of the metal grid line in the N region in the first unit and the width of the metal grid line in the N region in the second unit are in a ratio of 0.05:20. 8 . The solar cell according to claim 6 , wherein the distance between the metal grid line and the adjacent G region is not less than 25 μm.