Back contact solar cell, cell module and photovoltaic system

Abstract

The invention relates to the technical field of solar cells, and particularly discloses a back contact solar cell, a cell module and a photovoltaic system, and the cell comprises a silicon substrate which is provided with a light receiving surface and a backlight surface which are opposite to each other; n-type doping layers and P-type doping layers which are alternately arranged at intervals are arranged on the backlight face, the conductivity of the N-type doping layers is larger than that of the P-type doping layers, and the doping concentration of N-type doping agents in the N-type doping layers is larger than that of P-type doping agents in the P-type doping layers. According to the invention, a large potential gradient between the P-type doping layer and the N-type doping layer through the silicon substrate can be realized, and the separation of photo-generated electron hole pairs is enhanced. The large potential gradient is beneficial for electrons to rapidly enter the N-type doping layer and holes to rapidly enter the P-type doping layer, collected charges can be transmitted to the metal collecting electrodes corresponding to the metal grid lines more rapidly, meanwhile, series resistance can be effectively reduced, power loss in the battery is reduced, filling factors are improved, and the service life of the battery is prolonged. And the cell conversion efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a back-contact solar cell, a cell assembly and a photovoltaic system. Background Art

[0002] In current conventional solar cells, the front electrode and the back electrode are respectively arranged on the light-receiving side and the light-proof side of the substrate. The current transmission of carriers inside the battery is mainly longitudinal transmission. However, since the front electrode covers the light-receiving surface of the substrate, part of the incident light is reflected by the front electrode, which will cause optical loss and affect the energy conversion efficiency of the battery.

[0003] Compared with conventional solar cells, back-contact cells form alternating P-type doped regions and N-type doped regions on the backlit surface, with metal electrodes correspondingly covering the backlit surface. The current transmission of carriers inside the cell is mainly lateral transmission. Since there is no metal electrode blocking the light-receiving surface of the back-contact cell, shading losses can be avoided, which improves the conversion efficiency to a certain extent. However, due to the long lateral transmission distance, the lateral transmission of most carriers will cause significant series resistance loss, resulting in limited improvement in conversion efficiency.

[0004] In addition, in the prior art, the difficulty of collecting minority carriers is usually reduced by increasing the width of the P-type doping region so that the width of the P-type doping region is greater than that of the N-type doping region, thereby achieving the purpose of improving conversion efficiency. However, at the same time, the lateral transport distance of electrons will become longer, which will further increase the series resistance and result in limited effect on improving battery conversion efficiency. Summary of the invention

[0005] The purpose of the present invention is to provide a back-contact solar cell, a cell assembly and a photovoltaic system in view of the existing technical status.

[0006] The present invention can achieve a larger potential gradient between the P-type doped layer through the silicon substrate and then to the N-type doped layer, thereby strengthening the separation of photogenerated electron-hole pairs. The larger potential gradient is conducive to the rapid entry of electrons into the N-type doped layer and holes into the P-type doped layer, and the collected charges can be more quickly transmitted to the metal collecting electrode corresponding to the metal grid line. At the same time, it can effectively reduce the series resistance, reduce the power loss inside the battery, and improve the fill factor, thereby improving the battery conversion efficiency. In addition, high-doped phosphorus can maintain a good passivation effect, thereby increasing the doping concentration ratio of the N-type dopant in the N-type doping layer relative to the P-type dopant in the P-type doping layer, thereby improving the battery conversion efficiency.

[0007] In order to achieve the above object, the present invention adopts the following technical scheme:

[0008] First, the present invention provides a back-contact solar cell, comprising:

[0009] A silicon substrate, wherein the silicon substrate has a light-receiving surface and a backlight surface opposite to each other;

[0010] The backlight surface is provided with N-type doping layers and P-type doping layers arranged alternately and spaced apart.

[0011] The conductivity of the N-type doping layer is greater than the conductivity of the P-type doping layer, and the doping concentration of the N-type dopant in the N-type doping layer is greater than the doping concentration of the P-type dopant in the P-type doping layer.

[0012] In one embodiment, the doping concentration of the N-type dopant in the N-type doping layer is 1.5 to 12 times the doping concentration of the P-type dopant in the P-type doping layer.

[0013] In one embodiment, the doping concentration of the N-type dopant is 3 to 9 times the doping concentration of the P-type dopant.

[0014] In one embodiment, the doping concentration of the N-type dopant in the N-type doping layer is 0.4×10 20 cm -3 ~10×10 20 cm -3 In the P-type doping layer, the doping concentration of the P-type dopant is 0.1×10 20 cm -3 ~2.5×10 20 cm -3 .

[0015] In one embodiment, the conductivity of the N-type doped layer is 600 ohm. -1 .cm -1 ~2800ohm -1 .cm -1 , the conductivity of the P-type doped layer is 150 ohm -1 .cm -1 ~1000ohm -1 .cm -1 .

[0016] In one embodiment, the conductivity of the N-type doped layer is 1000 ohm. -1 .cm -1 ~1800ohm -1 .cm -1 , the conductivity of the P-type doped layer is 240ohm -1 .cm -1 ~450ohm -1 .cm -1 .

[0017] In one embodiment, the N-type doped layer is an N-type polysilicon material layer doped with an N-type dopant, the P-type doped layer is a P-type polysilicon material layer doped with a P-type dopant, and the width of the N-type doped layer is greater than the width of the P-type doped layer.

[0018] In one embodiment, the silicon substrate is an N-type single crystal silicon wafer or a P-type single crystal silicon wafer, and the doping concentration of the N-type single crystal silicon wafer or the P-type single crystal silicon wafer is less than 1×10 15 cm -3 .

[0019] In one embodiment, the width of the N-type doping layer is 1 to 5 times the width of the P-type doping layer.

[0020] In one embodiment, the width of the N-type doping layer is 1.4 to 3.2 times the width of the P-type doping layer.

[0021] In one embodiment, the width of the P-type doping layer is 100 μm to 900 μm.

[0022] In one embodiment, the width of the P-type doping layer is 200 μm to 500 μm.

[0023] In one embodiment, an isolation region is provided between adjacent N-type doping layers and P-type doping layers to separate the two, and the sum of the widths of a single N-type doping layer, two isolation regions and a single P-type doping layer is 0.3 mm to 3 mm.

[0024] In one embodiment, the sum of the widths of the single N-type doped layer, the two isolation regions, and the single P-type doped layer is 0.5 mm to 1.6 mm.

[0025] In one embodiment, the sheet resistance of the P-type doped layer is greater than the sheet resistance of the N-type doped layer.

[0026] In one embodiment, the square resistance of the P-type doped layer is 1.5 to 10 times the square resistance of the N-type doped layer.

[0027] In one embodiment, the sheet resistance of the N-type doped layer is 26 ohm / sq to 150 ohm / sq, and the sheet resistance of the P-type doped layer is 80 ohm / sq to 400 ohm / sq.

[0028] In one embodiment, the sheet resistance of the N-type doped layer is 35 ohm / sq to 120 ohm / sq, and the sheet resistance of the P-type doped layer is 90 ohm / sq to 350 ohm / sq.

[0029] In one embodiment, the sheet resistance of the N-type doped layer is 35 ohm / sq to 80 ohm / sq, and the sheet resistance of the P-type doped layer is 90 ohm / sq to 220 ohm / sq.

[0030] In one embodiment, a passivation layer is further provided on the backlight surface, the passivation layer is provided on the outside of the N-type doped layer and the P-type doped layer, and the passivation layer is provided with a first window and a second window, a metal gate line is provided outside the passivation layer, the metal gate line at least partially extends into the first window and contacts the N-type doped layer, and the metal gate line at least partially extends into the second window and contacts the P-type doped layer.

[0031] Secondly, the present invention provides a battery assembly, including the above-mentioned back-contact solar cell.

[0032] Furthermore, the present invention provides a photovoltaic system, comprising the above-mentioned battery assembly.

[0033] The beneficial effects of the present invention are:

[0034] 1) In the present invention, by controlling the doping concentration of the N-type dopant in the N-type doping layer to be greater than the doping concentration of the P-type dopant in the P-type doping layer, the conductivity of the N-type doping layer is made higher than the conductivity of the P-type doping layer, thereby achieving a larger potential gradient from the P-type doping layer through the silicon substrate to the N-type doping layer, thereby enhancing the separation of photogenerated electron-hole pairs. Among them, the one of the N-type doping layer and the P-type doping layer with the same polarity as the silicon substrate forms a high-low junction with the silicon substrate, and the one of the N-type doping layer and the P-type doping layer with different polarity from the silicon substrate forms a pn junction with the silicon substrate. The larger potential gradient is conducive to the rapid entry of electrons into the N-type doping layer and the rapid entry of holes into the P-type doping layer, and the collected charges can be more quickly transmitted to the metal collection electrode corresponding to the metal gate line. At the same time, it can effectively reduce the series resistance, reduce the power loss inside the battery, and improve the fill factor, thereby improving the battery conversion efficiency. In addition, the P-type dopant in the P-type doping layer is mostly boron, and the N-type dopant in the N-type doping layer is mostly phosphorus. During the preparation process, when the P-type doping concentration of the silicon wafer is too high, the boron doping concentration in the silicon substrate below the P-type doping layer is too high, and the BO pair in the silicon substrate below the P-type doping layer is a harmful recombination center, while the high-doped phosphorus can maintain a good passivation effect, thereby improving the battery conversion efficiency by increasing the doping concentration ratio of the N-type dopant in the N-type doping layer relative to the P-type dopant in the P-type doping layer.

[0035] 2) Due to the high doping and high conductivity of the N-type doped layer compared to the P-type doped layer, the lateral transmission capacity of the N-type doped layer is stronger than that of the P-type doped layer, and the transmission distance is longer. Therefore, through the low-concentration doped silicon substrate, combined with the setting that the width of the N-type doped layer is greater than the width of the P-type doped layer, according to the corresponding lateral transmission capacity of the two, the carrier transmission distance is matched, and the current collection is balanced to obtain a smaller series resistance and a higher fill factor, further improving the conversion efficiency. At the same time, since the passivation characteristics of the N-type doped layer are better than those of the P-type doped layer, by reducing the width of the P-type doped layer and increasing the width of the N-type doped layer, the proportion of the passivation contact area of ​​the N-type polysilicon material layer is higher, which can make the overall comprehensive passivation level of the battery higher and the composite loss lower, further improving the conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic structural diagram of the back contact solar cell of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in further detail below.

[0038] First, see Figure 1 As shown, the present invention provides a back contact solar cell, comprising:

[0039] A silicon substrate 1, wherein the silicon substrate has a light-receiving surface and a backlight surface opposite to each other;

[0040] The backlight surface is provided with N-type doping layers 2 and P-type doping layers 3 arranged alternately.

[0041] The conductivity of the N-type doping layer is greater than the conductivity of the P-type doping layer, and the doping concentration of the N-type dopant in the N-type doping layer is greater than the doping concentration of the P-type dopant in the P-type doping layer.

[0042] The silicon substrate may be an N-type single crystal silicon wafer or a P-type single crystal silicon wafer.

[0043] In this embodiment, by controlling the doping concentration of the N-type dopant in the N-type doping layer to be greater than the doping concentration of the P-type dopant in the P-type doping layer, the conductivity of the N-type doping layer is made higher than the conductivity of the P-type doping layer, thereby achieving a larger potential gradient from the P-type doping layer through the silicon substrate to the N-type doping layer, thereby enhancing the separation of photogenerated electron-hole pairs. Among them, the one of the N-type doping layer and the P-type doping layer with the same polarity as the silicon substrate forms a high-low junction with the silicon substrate, and the one of the N-type doping layer and the P-type doping layer with different polarity from the silicon substrate forms a pn junction with the silicon substrate. The larger potential gradient is conducive to the rapid entry of electrons into the N-type doping layer and the rapid entry of holes into the P-type doping layer, and the collected charges can be more quickly transmitted to the metal collection electrode corresponding to the metal gate line. At the same time, it can effectively reduce the series resistance, reduce the power loss inside the battery, and improve the fill factor, thereby improving the battery conversion efficiency. In addition, the P-type dopant in the P-type doping layer is mostly boron, and the N-type dopant in the N-type doping layer is mostly phosphorus. During the preparation process, when the P-type doping concentration of the silicon wafer is too high, the boron doping concentration in the silicon substrate below the P-type doping layer is too high, and the BO pair in the silicon substrate below the P-type doping layer is a harmful recombination center, while the high-doped phosphorus can maintain a good passivation effect, thereby improving the battery conversion efficiency by increasing the doping concentration ratio of the N-type dopant in the N-type doping layer relative to the P-type dopant in the P-type doping layer.

[0044] Preferably, the silicon substrate is an N-type single crystal silicon wafer, and more preferably, the silicon substrate is an N-type single crystal silicon wafer.

[0045] Wherein, the doping concentration of the N-type dopant in the N-type doping layer is 1.5 to 12 times the doping concentration of the P-type dopant in the P-type doping layer.

[0046] When the doping concentration difference between the two is too low, it is difficult to achieve a larger potential gradient between the P-type doping layer through the silicon substrate and then to the N-type doping layer. When the doping concentration difference between the two is too high, it is difficult to balance the current collection, which can easily cause irregular changes in carrier transport and lead to a significant decrease in conversion efficiency.

[0047] The N-type dopant is a Group V element, and exemplarily, the N-type dopant is phosphorus, but not limited thereto; the P-type dopant is a Group III element, and exemplarily, the P-type dopant is boron, but not limited thereto.

[0048] Exemplarily, the doping concentration of the N-type dopant in the N-type doping layer is 1.5 times, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times or 12 times the doping concentration of the P-type dopant in the P-type doping layer, but is not limited thereto.

[0049] Among them, the doping concentration of the N-type dopant is 3 to 9 times the doping concentration of the P-type dopant. Since the doping concentration of the N-type dopant and the doping concentration of the P-type dopant need to be maintained at a relatively high doping concentration, within this range, while ensuring that the battery conversion efficiency is significantly improved, the doping concentration of the N-type dopant does not need to be set too high, thereby reducing production costs and production difficulties.

[0050] Exemplarily, the doping concentration of the N-type dopant in the N-type doping layer is 3 times, 3.5 times, 4 times, 4.5 times, 5 times, 5.5 times, 6 times, 6.5 times, 7 times, 7.5 times, 8 times, 8.5 times or 9 times the doping concentration of the P-type dopant in the P-type doping layer, but is not limited to this.

[0051] Wherein, in the N-type doping layer, the doping concentration of the N-type dopant is 0.4×10 20 cm -3 ~10×10 20 cm -3 In the P-type doping layer, the doping concentration of the P-type dopant is 0.1×10 20 cm -3 ~2.5×10 20 cm -3 .

[0052] When the doping concentration of the P-type dopant in the P-type doping layer is too low or the doping concentration of the N-type dopant in the N-type doping layer is too low, it is difficult to form a high-intensity electric field between the N-type doping layer and the P-type doping layer, and it is difficult to effectively separate electron holes. When the doping concentration of the N-type dopant in the N-type doping layer is too low, it is difficult to form a sufficiently large concentration difference and conductivity difference with the P-type dopant in the P-type doping layer. When the doping concentration of the N-type dopant in the N-type doping layer is too high, the doping difficulty increases. When the doping concentration of the P-type dopant in the P-type doping layer is too high, it is difficult to form a sufficiently large concentration difference and conductivity difference with the P-type dopant in the P-type doping layer. At the same time, the doping difficulty increases, and harmful recombination centers increase.

[0053] For example, in the N-type doping layer, the doping concentration of the N-type dopant is 0.4×10 20 cm -3 , 0.5×10 20 cm -3 , 0.8×10 20 cm -3 , 1×10 20 cm -3 , 2×10 20 cm -3 , 3×10 20 cm -3 , 4×10 20 cm -3, 5×10 20 cm -3 , 6×10 20 cm -3 ,7×10 20 cm -3 , 8×10 20 cm -3 ,9×10 20 cm -3 or 10×10 20 cm -3 , but not limited to this.

[0054] For example, in the P-type doping layer, the doping concentration of the P-type dopant is 0.1×10 20 cm -3 , 0.2×10 20 cm -3 , 0.5×10 20 cm -3 , 0.8×10 20 cm -3 , 1×10 20 cm -3 , 1.2×10 20 cm -3 , 1.5×10 20 cm -3 , 1.8×10 20 cm -3 , 2×10 20 cm -3 , 2.2×10 20 cm -3 or 2.5 × 10 20 cm -3 , but not limited to this.

[0055] Wherein, the conductivity of the N-type doped layer is 600 ohm -1 .cm -1 ~2800ohm -1 .cm -1 , the conductivity of the P-type doped layer is 150 ohm -1 .cm -1 ~1000ohm -1 .cm -1 .

[0056] When the conductivity of the N-type doped layer or the conductivity of the P-type doped layer is too low, the current transmission efficiency is reduced, which can easily increase the surface recombination efficiency and the recombination loss during the transmission process, resulting in a decrease in conversion efficiency. When the conductivity of the N-type doped layer or the conductivity of the P-type doped layer is too high, the preparation difficulty increases, which can easily reduce the lattice quality and affect the conversion efficiency.

[0057] Exemplarily, the conductivity of the N-type doped layer is 600 ohm -1 .cm -1 、650ohm -1 .cm -1 、700ohm -1 .cm -1 、750ohm -1 .cm -1 、800ohm -1 .cm -1 、850ohm -1 .cm -1 、900ohm -1 .cm -1 、950ohm -1 .cm -1 、1000ohm - 1 .cm -1 、1050ohm -1 .cm -1 、1100ohm -1 .cm -1 、1150ohm -1 .cm -1 、1200ohm -1 .cm -1 、1250ohm -1 .cm -1 、1300ohm -1 .cm -1 、1350ohm -1 .cm -1 、1400ohm -1 .cm -1 、1450ohm -1 .cm -1 、1500ohm -1 .cm -1 、1550ohm -1 .cm -1 、1600ohm -1 .cm -1 、1650ohm -1 .cm -1 、1700ohm -1 .cm -1 、1750ohm -1 .cm -1 、1800ohm -1 .cm -1 、1850ohm -1 .cm -1、1900ohm -1 .cm -1 、1950ohm -1 .cm -1 、2000ohm -1 .cm -1 、2100ohm -1 .cm -1 、2150ohm -1 .cm -1 、2200ohm -1 .cm -1 、2250ohm -1 .cm -1 、2300ohm -1 .cm -1 、2350ohm -1 .cm -1 、2400ohm -1 .cm -1 、2450ohm -1 .cm -1 、2500ohm -1 .cm -1 、2550ohm -1 .cm -1 、2600ohm -1 .cm -1 、2650ohm -1 .cm -1 、2700ohm -1 .cm -1 、2750ohm -1 .cm -1 or 2800ohm -1 .cm -1 , but not limited to this.

[0058] For example, the conductivity of the P-type doped layer is 150 ohm. -1 .cm -1 、200ohm -1 .cm -1 、250ohm -1 .cm -1 、300ohm -1 .cm -1 、350ohm -1 .cm -1 、400ohm -1 .cm -1 、450ohm -1 .cm -1 、500ohm -1 .cm -1、550ohm -1 .cm -1 、600ohm -1 .cm -1 、650ohm -1 .cm -1 、700ohm -1 .cm -1 、750ohm -1 .cm -1 、800ohm -1 .cm -1 、850ohm -1 .cm -1 、900ohm -1 .cm -1 、950ohm -1 .cm -1 or 1000ohm -1 .cm -1 , but not limited to this.

[0059] Wherein, the conductivity of the N-type doped layer is 1000 ohm -1 .cm -1 ~1800ohm -1 .cm -1 , the conductivity of the P-type doped layer is 240ohm -1 .cm -1 ~450ohm -1 .cm -1 .

[0060] For example, the conductivity of the N-type doped layer is 1000 hm -1 .cm -1 、1050ohm -1 .cm -1 、1100ohm - 1 .cm -1 、1120ohm -1 .cm -1 、1150ohm -1 .cm -1 、1180ohm -1 .cm -1 、1200ohm -1 .cm -1 、1230ohm -1 .cm -1 、1250ohm -1 .cm -1 、1280ohm -1 .cm -1 、1300ohm-1 .cm -1 、1320ohm -1 .cm -1 、1350ohm -1 .cm -1 、1380ohm -1 .cm -1 、1400ohm -1 .cm -1 、1420ohm -1 .cm -1 、1450ohm -1 .cm -1 、1480ohm -1 .cm -1 、1500ohm -1 .cm -1 、1520ohm -1 .cm -1 、1550ohm -1 .cm -1 、1580ohm -1 .cm -1 、1600ohm -1 .cm -1 、1620ohm -1 .cm -1 、1650ohm -1 .cm -1 、1680ohm -1 .cm -1 、1700ohm -1 .cm -1 、1720ohm -1 .cm -1 、1750ohm -1 .cm -1 、1780ohm -1 .cm -1 or 1800ohm -1 .cm -1 , but not limited to this.

[0061] For example, the conductivity of the P-type doped layer is 240 ohm. -1 .cm -1 、250ohm -1 .cm -1 、280ohm -1 .cm -1 、300ohm -1 .cm -1 、320ohm -1 .cm -1、350ohm -1 .cm -1 、380ohm -1 .cm -1 、400ohm -1 .cm -1 、420ohm -1 .cm -1 or 450ohm -1 .cm -1 , but not limited to this.

[0062] Among them, see Figure 1 As shown, the N-type doped layer is an N-type polysilicon material layer doped with an N-type dopant, the P-type doped layer is a P-type polysilicon material layer doped with a P-type dopant, the silicon substrate is an N-type single crystal silicon wafer or a P-type single crystal silicon wafer, and the doping concentration of the N-type single crystal silicon wafer or the P-type single crystal silicon wafer is less than 1×10 15 cm -3 , the width of the N-type doped layer is greater than the width of the P-type doped layer, wherein the width of the N-type doped layer is W N , the width of the P-type doped layer is W P .

[0063] Compared with a high-concentration doped silicon wafer as a substrate, the present invention adopts a low-concentration doped silicon substrate, with extremely low intrinsic electron / hole concentration and a higher minority carrier lifetime, which is conducive to longer distance transmission.

[0064] In the present invention, the silicon substrate is doped at a low concentration, thereby forming a large doping concentration difference between the silicon substrate and the N-type doping layer and the P-type doping layer. The N-type doping layer and the P-type doping layer are doped at a high concentration compared to the silicon substrate. At this time, there is also a large conductivity difference between the silicon substrate and the N-type doping layer and the P-type doping layer. The N-type doping layer and the P-type doping layer are set with high conductivity compared to the silicon substrate. This high doping concentration difference and high conductivity difference setting enable the N-type doping layer and the P-type doping layer to form a larger potential gradient with the low-doped and low-conductivity silicon substrate, respectively, thereby enhancing the electric field strength, more effectively separating electrons and holes, and strengthening the lateral transmission capability of carriers.

[0065] Due to the high doping and high conductivity of the N-type doped layer compared to the P-type doped layer, the lateral transmission capacity of the N-type doped layer is stronger than that of the P-type doped layer, and the transmission distance is longer. Therefore, through the low-concentration doped silicon substrate, combined with the setting that the width of the N-type doped layer is greater than the width of the P-type doped layer, according to the corresponding lateral transmission capacity of the two, the carrier transmission distance is matched, and the current collection is balanced to obtain a smaller series resistance and a higher fill factor, further improving the conversion efficiency. At the same time, since the passivation characteristics of the N-type doped layer are better than those of the P-type doped layer, by reducing the width of the P-type doped layer and increasing the width of the N-type doped layer, the proportion of the passivation contact area of ​​the N-type polysilicon material layer is higher, which can make the overall comprehensive passivation level of the battery higher and the composite loss lower, further improving the conversion efficiency.

[0066] At the same time, since the passivation characteristics of the N-type doped layer are better than those of the P-type doped layer, this means that compared with the N-type doped layer, the Auger recombination rate near the interface between the P-type doped layer and the silicon substrate is higher, which is more likely to cause current loss. Therefore, by reducing the width of the P-type doped layer and increasing the width of the N-type doped layer, the passivation contact area of ​​the N-type polysilicon material layer accounts for a higher proportion, which can make the overall comprehensive passivation level of the battery higher and the recombination loss lower, further improving the conversion efficiency.

[0067] Wherein, the width of the N-type doping layer is 1 to 5 times the width of the P-type doping layer.

[0068] When the ratio between the width of the N-type doped layer and the width of the P-type doped layer is too low, the improvement effect of the series resistance and the fill factor is not good. When the ratio between the width of the N-type doped layer and the width of the P-type doped layer is too high, the width of the P-type doped layer is too narrow and the short-circuit current is too low, which affects the conversion efficiency.

[0069] Exemplarily, the width of the N-type doped layer is 1 times, 1.3 times, 1.5 times, 1.8 times, 2.0 times, 2.5 times, 2.8 times, 3.0 times, 3.5 times, 4.0 times, 4.5 times or 5 times the width of the P-type doped layer, but is not limited thereto.

[0070] Wherein, the width of the N-type doping layer is 1.4 to 3.2 times the width of the P-type doping layer.

[0071] Exemplarily, the width of the N-type doped layer is 1.4 times, 1.5 times, 1.6 times, 1.7 times, 1.8 times, 2.0 times, 2.1 times, 2.2 times, 2.3 times, 2.4 times, 2.5 times, 2.6 times, 2.7 times, 2.8 times, 2.9 times, 3.0 times, 3.1 times or 3.2 times the width of the P-type doped layer, but is not limited to this.

[0072] Wherein, the width of the P-type doping layer is 100 μm to 900 μm.

[0073] When the width of the P-type doped layer is too large, the N-type doped layer needs to be set to a larger width, which increases the total width of the N-type doped layer and the P-type doped layer, increases the lateral transport distance of the carriers, and increases the recombination loss during the transport process. The number of N-type doped layers and P-type doped layers that can be arranged in the same battery decreases, and the number of corresponding metal grid lines set on the outside decreases accordingly, and the current collection capacity decreases, affecting the conversion efficiency.

[0074] Exemplarily, the width of the P-type doped layer is 100μm, 150μm, 200μm, 250μm, 300μm, 350μm, 400μm, 450μm, 500μm, 550μm, 600μm, 650μm, 700μm, 750μm, 800μm, 850μm or 900μm, but is not limited thereto.

[0075] Among them, see Figure 1 As shown, an isolation region 6 is provided between the adjacent N-type doped layers and the P-type doped layers to separate the two. The sum of the widths of a single N-type doped layer, two isolation regions and a single P-type doped layer (hereinafter referred to as "unit width") is 0.3 mm to 3 mm, wherein the width of the isolation region is W G .

[0076] On the basis of controlling the width ratio of the N-type doped layer and the P-type doped layer, the unit width can be further controlled to maximize charge collection. Within this unit width range, the lateral transport distance of the carriers is further shortened, the series resistance is reduced, the fill factor is improved, and the battery conversion efficiency is effectively improved.

[0077] When the unit width is too small, the difficulty of preparation increases, and it is easy to cause the N-type doped layer and the P-type doped layer to overlap. At the same time, due to technical limitations, the isolation area has a narrowest width. When the unit width is too small, it is easy for the isolation area to occupy too large a proportion of the entire unit width, and the surface recombination loss of the isolation area increases, which will cause the battery conversion efficiency to decrease.

[0078] When the cell width is too large, the electric field strength between the N-type doped layer and the P-type doped layer is weakened, the lateral transport distance is extended, it is difficult to form effective carrier collection, and the battery conversion efficiency decreases.

[0079] Exemplarily, the sum of the widths of the single N-type doped layer, the two isolation regions, and the single P-type doped layer is 0.3 mm, 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, or 3.0 mm, but is not limited thereto.

[0080] Among them, the sum of the widths of a single N-type doped layer, two isolation regions and a single P-type doped layer is 0.5 mm to 1.6 mm. Within this range, the battery conversion efficiency is high and the preparation difficulty is relatively low, ensuring a higher production yield and better overall performance.

[0081] Exemplarily, the sum of the widths of a single N-type doped layer, two isolation regions, and a single P-type doped layer is 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, or 1.6 mm, but is not limited thereto.

[0082] Wherein, the sheet resistance of the P-type doped layer is greater than the sheet resistance of the N-type doped layer.

[0083] The N-type doped layer has low square resistance and stronger lateral transport capability than the P-type doped layer. The width of the N-type doped layer can be set to be larger than that of the P-type doped layer, thereby improving the series resistance and fill factor while balancing current collection, thereby improving conversion efficiency.

[0084] The square resistance of the P-type doped layer is 1.5 to 10 times that of the N-type doped layer.

[0085] Exemplarily, the square resistance of the P-type doped layer is 1.5 times, 2.0 times, 2.5 times, 3.0 times, 3.5 times, 4.0 times, 4.5 times, 5.0 times, 5.5 times, 6.0 times, 6.5 times, 7.0 times, 7.5 times, 8.0 times, 8.5 times, 9.0 times, 9.5 times or 10 times the square resistance of the N-type doped layer, but is not limited to this.

[0086] The sheet resistance of the N-type doped layer is 26 ohm / sq to 150 ohm / sq, and the sheet resistance of the P-type doped layer is 80 ohm / sq to 400 ohm / sq.

[0087] Exemplarily, the square resistance of the N-type doped layer is 26ohm / sq, 30ohm / sq, 35ohm / sq, 40ohm / sq, 45ohm / sq, 50ohm / sq, 55ohm / sq, 60ohm / sq, 65ohm / sq, 70ohm / sq, 75ohm / sq, 80ohm / sq, 85ohm / sq, 90ohm / sq, 95ohm / sq, 100ohm / sq, 105ohm / sq, 110ohm / sq, 115ohm / sq, 120ohm / sq, 125ohm / sq, 130ohm / sq, 135ohm / sq, 140ohm / sq, 145ohm / sq or 150ohm / sq, but is not limited to this.

[0088] For example, the square resistance of the P-type doped layer is 80 ohm / sq, 90 ohm / sq, 100 ohm / sq, 110 ohm / sq, 120 ohm / sq, 130 ohm / sq, 140 ohm / sq, 150 ohm / sq, 160 ohm / sq, 170 ohm / sq, 180 ohm / sq, 190 ohm / sq, 200 ohm / sq, 210 ohm / sq, 220 ohm / sq, 230 ohm / sq, 240 ohm / sq, 250 ohm / sq, 260 ohm / sq, 270 ohm / sq, 280 ohm / sq, 290 ohm / sq, 300 ohm / sq, 310 ohm / sq, 320 ohm / sq, 330 ohm / sq, 340 ohm / sq, 350 ohm / sq, 360 ohm / sq, 370 ohm / sq, 380 ohm / sq, 390 ohm / sq, 400 ohm / sq, 410 ohm / sq, 420 ohm / sq, 430 ohm / sq, 440 ohm sq, 350ohm / sq, 360ohm / sq, 370ohm / sq, 380ohm / sq, 390ohm / sq or 400ohm / sq, but not limited to, 40ohm / sq, 250ohm / sq, 260ohm / sq, 270ohm / sq, 280ohm / sq, 290ohm / sq, 300ohm / sq, 310ohm / sq, 320ohm / sq, 330ohm / sq, 340ohm / sq, 350ohm / sq, 360ohm / sq, 370ohm / sq, 380ohm / sq, 390ohm / sq or 400ohm / sq.

[0089] The sheet resistance of the N-type doped layer is 35 ohm / sq to 120 ohm / sq, and the sheet resistance of the P-type doped layer is 90 ohm / sq to 350 ohm / sq.

[0090] Exemplarily, the square resistance of the N-type doped layer is 35ohm / sq, 40ohm / sq, 45ohm / sq, 50ohm / sq, 55ohm / sq, 60ohm / sq, 65ohm / sq, 70ohm / sq, 75ohm / sq, 80ohm / sq, 85ohm / sq, 90ohm / sq, 95ohm / sq, 100ohm / sq, 105ohm / sq, 110ohm / sq, 115ohm / sq or 120ohm / sq, but is not limited to this.

[0091] Exemplarily, the square resistance of the P-type doped layer is 90 ohm / sq, 100 ohm / sq, 110 ohm / sq, 120 ohm / sq, 130 ohm / sq, 140 ohm / sq, 150 ohm / sq, 160 ohm / sq, 170 ohm / sq, 180 ohm / sq, 190 ohm / sq, 200 ohm / sq, 210 ohm / sq, 220ohm / sq, 230ohm / sq, 240ohm / sq, 250ohm / sq, 260ohm / sq, 270ohm / sq, 280ohm / sq, 290ohm / sq, 300ohm / sq, 310ohm / sq, 320ohm / sq, 330ohm / sq, 340ohm / sq or 350ohm / sq, but not limited to these.

[0092] The sheet resistance of the N-type doped layer is 35 ohm / sq to 80 ohm / sq, and the sheet resistance of the P-type doped layer is 90 ohm / sq to 220 ohm / sq.

[0093] Exemplarily, the square resistance of the N-type doped layer is 35ohm / sq, 38ohm / sq, 40ohm / sq, 42ohm / sq, 45ohm / sq, 48ohm / sq, 50ohm / sq, 52ohm / sq, 55ohm / sq, 58ohm / sq, 60ohm / sq, 62ohm / sq, 65ohm / sq, 67ohm / sq, 70ohm / sq, 73ohm / sq, 75ohm / sq, 78ohm / sq or 80ohm / sq, but is not limited to this.

[0094] For example, the square resistance of the P-type doped layer is 90 ohm / sq, 95 ohm / sq, 100 ohm / sq, 105 ohm / sq, 110 ohm / sq, 115 ohm / sq, 120 ohm / sq, 125 ohm / sq, 130 ohm / sq, 135 ohm / sq, 140 ohm / sq, 145 ohm / sq, 150 ohm / sq, 1 sq, 55ohm / sq, 160ohm / sq, 165ohm / sq, 170ohm / sq, 175ohm / sq, 180ohm / sq, 185ohm / sq, 190ohm / sq, 195ohm / sq, 200ohm / sq, 205ohm / sq, 210ohm / sq, 215ohm / sq or 220ohm / sq, but not limited to.

[0095] Among them, see Figure 1 As shown, a passivation layer 4 is also provided on the backlight surface, and the passivation layer is provided on the outside of the N-type doped layer and the P-type doped layer, and the passivation layer is provided with a first window and a second window, and a metal gate line 5 is provided outside the passivation layer, and the metal gate line at least partially extends into the first window and contacts with the N-type doped layer, and the metal gate line at least partially extends into the second window and contacts with the P-type doped layer, and the metal gate line forms an ohmic contact with the N-type doped layer and the P-type doped layer.

[0096] The passivation layer may be at least one of a silicon nitride material layer, a silicon oxide material layer, a silicon oxynitride material layer, and an intrinsic amorphous silicon material layer.

[0097] The passivation layer effectively reduces the recombination of minority carriers and surface states on the back of the battery, which helps to improve the photoelectric conversion efficiency of the battery.

[0098] Exemplarily, the metal gate line includes an N-type fine gate and a P-type fine gate, the N-type fine gate is arranged in the first window, the P-type fine gate is arranged in the second window, the length direction of the N-type fine gate is arranged along the length direction of the N-type doped layer, and the length direction of the P-type fine gate is arranged along the length direction of the P-type doped layer.

[0099] Exemplarily, the metal gate line further includes an N-type main gate for connecting an N-type fine gate and a P-type main gate for connecting a P-type fine gate. The N-type main gate is arranged to cross the N-type fine gate, and the P-type main gate is arranged to cross the P-type fine gate.

[0100] Secondly, the present invention provides a battery assembly, including the above-mentioned back-contact solar cell.

[0101] Furthermore, the present invention provides a photovoltaic system, comprising the above-mentioned battery assembly.

[0102] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0103] Example 1

[0104] This embodiment discloses a back-contact solar cell, comprising:

[0105] A silicon substrate, wherein the silicon substrate has a light-receiving surface and a backlight surface opposite to each other;

[0106] The backlight surface is provided with N-type doping layers and P-type doping layers arranged alternately and spaced apart.

[0107] The conductivity of the N-type doping layer is greater than the conductivity of the P-type doping layer, and the doping concentration of the N-type dopant in the N-type doping layer is greater than the doping concentration of the P-type dopant in the P-type doping layer.

[0108] The doping concentration of the N-type dopant in the N-type doping layer is 3.33 times the doping concentration of the P-type dopant in the P-type doping layer.

[0109] Wherein, in the N-type doping layer, the doping concentration of the N-type dopant is 0.5×10 20 cm -3 In the P-type doping layer, the doping concentration of the P-type dopant is 0.15×10 20 cm -3 .

[0110] Wherein, the conductivity of the N-type doped layer is 600 ohm -1 .cm -1 , the conductivity of the P-type doped layer is 150 ohm -1 .cm -1 .

[0111] Among them, see Figure 1As shown, the N-type doped layer is an N-type polysilicon material layer doped with an N-type dopant, the P-type doped layer is a P-type polysilicon material layer doped with a P-type dopant, and the silicon substrate is an N-type silicon substrate, and the doping concentration of the N-type silicon substrate is 4.5×10 14 cm -3 , the width of the N-type doping layer is greater than the width of the P-type doping layer.

[0112] Wherein, the width of the N-type doping layer is 3.2 times the width of the P-type doping layer.

[0113] Wherein, the width of the P-type doping layer is 400 μm.

[0114] Among them, see Figure 1 As shown, an isolation region is provided between adjacent N-type doped layers and P-type doped layers to separate the two, and the sum of the widths of a single N-type doped layer, two isolation regions and a single P-type doped layer (hereinafter referred to as "unit width") is 1.78 mm.

[0115] Wherein, the sheet resistance of the P-type doped layer is greater than the sheet resistance of the N-type doped layer.

[0116] The square resistance of the P-type doped layer is 2.67 times that of the N-type doped layer.

[0117] The sheet resistance of the N-type doped layer is 150 ohm / sq, and the sheet resistance of the P-type doped layer is 400 ohm / sq.

[0118] Among them, see Figure 1 As shown, a passivation layer is also provided on the backlight surface, and the passivation layer is provided on the outside of the N-type doped layer and the P-type doped layer, and the passivation layer is provided with a first window and a second window, and a metal gate line is provided outside the passivation layer, and the metal gate line at least partially extends into the first window and contacts with the N-type doped layer, and the metal gate line at least partially extends into the second window and contacts with the P-type doped layer, and the metal gate line forms an ohmic contact with the N-type doped layer and the P-type doped layer.

[0119] This embodiment also discloses a battery assembly, including the above-mentioned back-contact solar cell.

[0120] This embodiment also discloses a photovoltaic system, including the above-mentioned battery assembly.

[0121] Example 2

[0122] This embodiment discloses a back-contact solar cell, comprising:

[0123] A silicon substrate, wherein the silicon substrate has a light-receiving surface and a backlight surface opposite to each other;

[0124] The backlight surface is provided with N-type doping layers and P-type doping layers arranged alternately and spaced apart.

[0125] The conductivity of the N-type doping layer is greater than the conductivity of the P-type doping layer, and the doping concentration of the N-type dopant in the N-type doping layer is greater than the doping concentration of the P-type dopant in the P-type doping layer.

[0126] The doping concentration of the N-type dopant in the N-type doping layer is 4 times the doping concentration of the P-type dopant in the P-type doping layer.

[0127] Wherein, in the N-type doping layer, the doping concentration of the N-type dopant is 8×10 20 cm -3 In the P-type doping layer, the doping concentration of the P-type dopant is 2×10 20 cm -3 .

[0128] Wherein, the conductivity of the N-type doped layer is 2800 ohm -1 .cm -1 , the conductivity of the P-type doped layer is 1000ohm -1 .cm -1 .

[0129] Among them, see Figure 1 As shown, the N-type doped layer is an N-type polysilicon material layer doped with an N-type dopant, the P-type doped layer is a P-type polysilicon material layer doped with a P-type dopant, and the silicon substrate is an N-type silicon substrate, and the doping concentration of the N-type silicon substrate is 4.5×10 14 cm -3 , the width of the N-type doping layer is greater than the width of the P-type doping layer.

[0130] Wherein, the width of the N-type doping layer is 3.2 times the width of the P-type doping layer.

[0131] Wherein, the width of the P-type doping layer is 400 μm.

[0132] Among them, see Figure 1 As shown, an isolation region is provided between adjacent N-type doped layers and P-type doped layers to separate the two, and the sum of the widths of a single N-type doped layer, two isolation regions and a single P-type doped layer (hereinafter referred to as "unit width") is 1.78 mm.

[0133] Wherein, the sheet resistance of the P-type doped layer is greater than the sheet resistance of the N-type doped layer.

[0134] The square resistance of the P-type doped layer is 3.08 times that of the N-type doped layer.

[0135] The sheet resistance of the N-type doped layer is 26 ohm / sq, and the sheet resistance of the P-type doped layer is 80 ohm / sq.

[0136] Among them, see Figure 1 As shown, a passivation layer is also provided on the backlight surface, and the passivation layer is provided on the outside of the N-type doped layer and the P-type doped layer, and the passivation layer is provided with a first window and a second window, and a metal gate line is provided outside the passivation layer, and the metal gate line at least partially extends into the first window and contacts with the N-type doped layer, and the metal gate line at least partially extends into the second window and contacts with the P-type doped layer, and the metal gate line forms an ohmic contact with the N-type doped layer and the P-type doped layer.

[0137] This embodiment also discloses a battery assembly, including the above-mentioned back-contact solar cell.

[0138] This embodiment also discloses a photovoltaic system, including the above-mentioned battery assembly.

[0139] Example 3

[0140] This embodiment discloses a back-contact solar cell, comprising:

[0141] A silicon substrate, wherein the silicon substrate has a light-receiving surface and a backlight surface opposite to each other;

[0142] The backlight surface is provided with N-type doping layers and P-type doping layers arranged alternately and spaced apart.

[0143] The conductivity of the N-type doping layer is greater than the conductivity of the P-type doping layer, and the doping concentration of the N-type dopant in the N-type doping layer is greater than the doping concentration of the P-type dopant in the P-type doping layer.

[0144] The doping concentration of the N-type dopant in the N-type doping layer is 5 times the doping concentration of the P-type dopant in the P-type doping layer.

[0145] Wherein, in the N-type doping layer, the doping concentration of the N-type dopant is 4×10 20 cm -3 In the P-type doping layer, the doping concentration of the P-type dopant is 0.8×10 20 cm -3 .

[0146] Wherein, the conductivity of the N-type doped layer is 1800 ohm -1 .cm -1 , the conductivity of the P-type doped layer is 450ohm -1 .cm -1 .

[0147] Among them, see Figure 1 As shown, the N-type doped layer is an N-type polysilicon material layer doped with an N-type dopant, the P-type doped layer is a P-type polysilicon material layer doped with a P-type dopant, and the silicon substrate is an N-type silicon substrate, and the doping concentration of the N-type silicon substrate is 4.5×10 14 cm -3 , the width of the N-type doping layer is greater than the width of the P-type doping layer.

[0148] Wherein, the width of the N-type doping layer is 3.2 times the width of the P-type doping layer.

[0149] Wherein, the width of the P-type doping layer is 400 μm.

[0150] Among them, see Figure 1 As shown, an isolation region is provided between adjacent N-type doped layers and P-type doped layers to separate the two, and the sum of the widths of a single N-type doped layer, two isolation regions and a single P-type doped layer (hereinafter referred to as "unit width") is 1.78 mm.

[0151] Wherein, the sheet resistance of the P-type doped layer is greater than the sheet resistance of the N-type doped layer.

[0152] The square resistance of the P-type doped layer is 1.83 times that of the N-type doped layer.

[0153] The sheet resistance of the N-type doped layer is 120 ohm / sq, and the sheet resistance of the P-type doped layer is 220 ohm / sq.

[0154] Among them, see Figure 1 As shown, a passivation layer is also provided on the backlight surface, and the passivation layer is provided on the outside of the N-type doped layer and the P-type doped layer, and the passivation layer is provided with a first window and a second window, and a metal gate line is provided outside the passivation layer, and the metal gate line at least partially extends into the first window and contacts with the N-type doped layer, and the metal gate line at least partially extends into the second window and contacts with the P-type doped layer, and the metal gate line forms an ohmic contact with the N-type doped layer and the P-type doped layer.

[0155] This embodiment also discloses a battery assembly, including the above-mentioned back-contact solar cell.

[0156] This embodiment also discloses a photovoltaic system, including the above-mentioned battery assembly.

[0157] Example 4

[0158] This embodiment discloses a back-contact solar cell, comprising:

[0159] A silicon substrate, wherein the silicon substrate has a light-receiving surface and a backlight surface opposite to each other;

[0160] The backlight surface is provided with N-type doping layers and P-type doping layers arranged alternately and spaced apart.

[0161] The conductivity of the N-type doping layer is greater than the conductivity of the P-type doping layer, and the doping concentration of the N-type dopant in the N-type doping layer is greater than the doping concentration of the P-type dopant in the P-type doping layer.

[0162] The doping concentration of the N-type dopant in the N-type doping layer is 6.25 times the doping concentration of the P-type dopant in the P-type doping layer.

[0163] Wherein, in the N-type doping layer, the doping concentration of the N-type dopant is 5×10 20 cm -3 In the P-type doping layer, the doping concentration of the P-type dopant is 0.8×10 20 cm -3 .

[0164] Wherein, the conductivity of the N-type doped layer is 2500 ohm -1 .cm -1 , the conductivity of the P-type doped layer is 450ohm -1 .cm -1 .

[0165] Among them, see Figure 1 As shown, the N-type doped layer is an N-type polysilicon material layer doped with an N-type dopant, the P-type doped layer is a P-type polysilicon material layer doped with a P-type dopant, and the silicon substrate is an N-type silicon substrate, and the doping concentration of the N-type silicon substrate is 4.5×10 14 cm -3 , the width of the N-type doping layer is greater than the width of the P-type doping layer.

[0166] Wherein, the width of the N-type doping layer is 1.4 times the width of the P-type doping layer.

[0167] Wherein, the width of the P-type doping layer is 900 μm.

[0168] Among them, see Figure 1 As shown, an isolation region is provided between adjacent N-type doped layers and P-type doped layers to separate the two, and the sum of the widths of a single N-type doped layer, two isolation regions and a single P-type doped layer (hereinafter referred to as "unit width") is 2.26 mm.

[0169] Wherein, the sheet resistance of the P-type doped layer is greater than the sheet resistance of the N-type doped layer.

[0170] The square resistance of the P-type doped layer is 6.29 times that of the N-type doped layer.

[0171] The sheet resistance of the N-type doped layer is 35 ohm / sq, and the sheet resistance of the P-type doped layer is 220 ohm / sq.

[0172] Among them, see Figure 1 As shown, a passivation layer is also provided on the backlight surface, and the passivation layer is provided on the outside of the N-type doped layer and the P-type doped layer, and the passivation layer is provided with a first window and a second window, and a metal gate line is provided outside the passivation layer, and the metal gate line at least partially extends into the first window and contacts with the N-type doped layer, and the metal gate line at least partially extends into the second window and contacts with the P-type doped layer, and the metal gate line forms an ohmic contact with the N-type doped layer and the P-type doped layer.

[0173] This embodiment also discloses a battery assembly, including the above-mentioned back-contact solar cell.

[0174] This embodiment also discloses a photovoltaic system, including the above-mentioned battery assembly.

[0175] Example 5

[0176] This embodiment discloses a back-contact solar cell, comprising:

[0177] A silicon substrate, wherein the silicon substrate has a light-receiving surface and a backlight surface opposite to each other;

[0178] The backlight surface is provided with N-type doping layers and P-type doping layers arranged alternately and spaced apart.

[0179] The conductivity of the N-type doping layer is greater than the conductivity of the P-type doping layer, and the doping concentration of the N-type dopant in the N-type doping layer is greater than the doping concentration of the P-type dopant in the P-type doping layer.

[0180] The doping concentration of the N-type dopant in the N-type doping layer is 6.25 times the doping concentration of the P-type dopant in the P-type doping layer.

[0181] Wherein, in the N-type doping layer, the doping concentration of the N-type dopant is 5×10 20 cm -3 In the P-type doping layer, the doping concentration of the P-type dopant is 0.8×10 20 cm -3 .

[0182] Wherein, the conductivity of the N-type doped layer is 2500 ohm -1 .cm -1 , the conductivity of the P-type doped layer is 450ohm -1 .cm-1 .

[0183] Among them, see Figure 1 As shown, the N-type doped layer is an N-type polysilicon material layer doped with an N-type dopant, the P-type doped layer is a P-type polysilicon material layer doped with a P-type dopant, and the silicon substrate is an N-type silicon substrate, and the doping concentration of the N-type silicon substrate is 4.5×10 14 cm -3 , the width of the N-type doping layer is greater than the width of the P-type doping layer.

[0184] Wherein, the width of the N-type doping layer is 5 times the width of the P-type doping layer.

[0185] Wherein, the width of the P-type doping layer is 100 μm.

[0186] Among them, see Figure 1 As shown, an isolation region is provided between adjacent N-type doped layers and P-type doped layers to separate the two, and the sum of the widths of a single N-type doped layer, two isolation regions and a single P-type doped layer (hereinafter referred to as "unit width") is 0.7 mm.

[0187] Wherein, the sheet resistance of the P-type doped layer is greater than the sheet resistance of the N-type doped layer.

[0188] The square resistance of the P-type doped layer is 6.29 times that of the N-type doped layer.

[0189] The sheet resistance of the N-type doped layer is 35 ohm / sq, and the sheet resistance of the P-type doped layer is 220 ohm / sq.

[0190] Among them, see Figure 1 As shown, a passivation layer is also provided on the backlight surface, and the passivation layer is provided on the outside of the N-type doped layer and the P-type doped layer, and the passivation layer is provided with a first window and a second window, and a metal gate line is provided outside the passivation layer, and the metal gate line at least partially extends into the first window and contacts with the N-type doped layer, and the metal gate line at least partially extends into the second window and contacts with the P-type doped layer, and the metal gate line forms an ohmic contact with the N-type doped layer and the P-type doped layer.

[0191] This embodiment also discloses a battery assembly, including the above-mentioned back-contact solar cell.

[0192] This embodiment also discloses a photovoltaic system, including the above-mentioned battery assembly.

[0193] Example 6

[0194] This embodiment discloses a back-contact solar cell, comprising:

[0195] A silicon substrate, wherein the silicon substrate has a light-receiving surface and a backlight surface opposite to each other;

[0196] The backlight surface is provided with N-type doping layers and P-type doping layers arranged alternately and spaced apart.

[0197] The conductivity of the N-type doping layer is greater than the conductivity of the P-type doping layer, and the doping concentration of the N-type dopant in the N-type doping layer is greater than the doping concentration of the P-type dopant in the P-type doping layer.

[0198] The doping concentration of the N-type dopant in the N-type doping layer is 6.25 times the doping concentration of the P-type dopant in the P-type doping layer.

[0199] Wherein, in the N-type doping layer, the doping concentration of the N-type dopant is 5×10 20 cm -3 In the P-type doping layer, the doping concentration of the P-type dopant is 0.8×10 20 cm -3 .

[0200] Wherein, the conductivity of the N-type doped layer is 2500 ohm -1 .cm -1 , the conductivity of the P-type doped layer is 450ohm -1 .cm -1 .

[0201] Among them, see Figure 1 As shown, the N-type doped layer is an N-type polysilicon material layer doped with an N-type dopant, the P-type doped layer is a P-type polysilicon material layer doped with a P-type dopant, the silicon substrate is a P-type silicon substrate, and the doping concentration of the P-type silicon substrate is 4.5×10 14 cm -3 , the width of the N-type doping layer is greater than the width of the P-type doping layer.

[0202] Wherein, the width of the N-type doping layer is 5 times the width of the P-type doping layer.

[0203] Wherein, the width of the P-type doping layer is 100 μm.

[0204] Among them, see Figure 1 As shown, an isolation region is provided between adjacent N-type doped layers and P-type doped layers to separate the two, and the sum of the widths of a single N-type doped layer, two isolation regions and a single P-type doped layer (hereinafter referred to as "unit width") is 0.7 mm.

[0205] Wherein, the sheet resistance of the P-type doped layer is greater than the sheet resistance of the N-type doped layer.

[0206] The square resistance of the P-type doped layer is 6.29 times that of the N-type doped layer.

[0207] The sheet resistance of the N-type doped layer is 35 ohm / sq, and the sheet resistance of the P-type doped layer is 220 ohm / sq.

[0208] Among them, see Figure 1 As shown, a passivation layer is also provided on the backlight surface, and the passivation layer is provided on the outside of the N-type doped layer and the P-type doped layer, and the passivation layer is provided with a first window and a second window, and a metal gate line is provided outside the passivation layer, and the metal gate line at least partially extends into the first window and contacts with the N-type doped layer, and the metal gate line at least partially extends into the second window and contacts with the P-type doped layer, and the metal gate line forms an ohmic contact with the N-type doped layer and the P-type doped layer.

[0209] This embodiment also discloses a battery assembly, including the above-mentioned back-contact solar cell.

[0210] This embodiment also discloses a photovoltaic system, including the above-mentioned battery assembly.

[0211] Comparative Example 1

[0212] This comparative example discloses a back-contact solar cell, comprising:

[0213] A silicon substrate, wherein the silicon substrate has a light-receiving surface and a backlight surface opposite to each other;

[0214] The backlight surface is provided with N-type doping layers and P-type doping layers arranged alternately and spaced apart.

[0215] The doping concentration of the N-type dopant in the N-type doping layer is 0.15×10 20 cm -3 The doping concentration of the P-type dopant in the P-type doping layer is 0.5×10 20 cm -3 .

[0216] The conductivity of the N-type doped layer is 320 ohm -1 .cm -1 , the conductivity of the P-type doped layer is 380 ohm - 1 .cm -1 .

[0217] The N-type doped layer is an N-type polysilicon material layer doped with an N-type dopant, the P-type doped layer is a P-type polysilicon material layer doped with a P-type dopant, the silicon substrate is an N-type silicon substrate, and the doping concentration of the N-type silicon substrate is 4.5×10 14 cm-3 , the width of the P-type doping layer is greater than the width of the N-type doping layer.

[0218] Wherein, the ratio of the width of the N-type doping layer to the width of the P-type doping layer is 0.31.

[0219] Wherein, the width of the P-type doping layer is 1280 μm, and the width of the N-type doping layer is 400 μm.

[0220] Among them, an isolation region is provided between adjacent N-type doped layers and P-type doped layers to separate the two, and the sum of the widths of a single N-type doped layer, two isolation regions and a single P-type doped layer (hereinafter referred to as "unit width") is 1.78 mm.

[0221] The solar cells prepared in Examples 1 to 6 and Comparative Example 1 were tested for performance, and the test results are as follows:

[0222]

[0223] Compared with Comparative Example 1, the open circuit voltage, short circuit current and fill factor of Comparative Examples 1 to 5 of the present invention are significantly improved, and the conversion efficiency is effectively improved. Comparative Examples 1 to 3 show that the difference in doping concentration and conductivity between the N-type doping layer and the P-type doping layer has a great influence on the conversion efficiency. Comparative Examples 3 to 5 show that the width setting of the N-type doping layer and the P-type doping layer has a great influence on the conversion efficiency.

[0224] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with the field can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A back contact solar cell, characterized in that: include: A silicon substrate, wherein the silicon substrate has a light-receiving surface and a backlight surface opposite to each other; The backlight surface is provided with N-type doping layers and P-type doping layers arranged alternately and spaced apart. The conductivity of the N-type doping layer is greater than the conductivity of the P-type doping layer, and the doping concentration of the N-type dopant in the N-type doping layer is greater than the doping concentration of the P-type dopant in the P-type doping layer.

2. The back contact solar cell according to claim 1, characterized in that: The doping concentration of the N-type dopant in the N-type doping layer is 1.5 to 12 times the doping concentration of the P-type dopant in the P-type doping layer.

3. The back contact solar cell according to claim 2, characterized in that: The doping concentration of the N-type dopant is 3 to 9 times the doping concentration of the P-type dopant.

4. The back contact solar cell according to claim 1, characterized in that: In the N-type doping layer, the doping concentration of the N-type dopant is 0.4×10 20 cm -3 ~10×10 20 cm -3 In the P-type doping layer, the doping concentration of the P-type dopant is 0.1×10 20 cm -3 ~2.5×10 20 cm -3 .

5. The back contact solar cell according to claim 1, characterized in that: The conductivity of the N-type doped layer is 600 ohm -1 .cm -1 ~2800ohm -1 .cm -1 , the conductivity of the P-type doped layer is 150 ohm -1 .cm -1 ~1000ohm -1 .cm -1 .

6. The back contact solar cell according to claim 5, characterized in that: The conductivity of the N-type doped layer is 1000 ohm -1 .cm -1 ~1800ohm -1 .cm -1 , the conductivity of the P-type doped layer is 240ohm -1 .cm -1 ~450ohm -1 .cm -1 .

7. The back contact solar cell according to claim 1, characterized in that: The N-type doped layer is an N-type polysilicon material layer doped with an N-type dopant, the P-type doped layer is a P-type polysilicon material layer doped with a P-type dopant, and the width of the N-type doped layer is greater than the width of the P-type doped layer.

8. The back contact solar cell according to claim 7, characterized in that: The silicon substrate is an N-type single crystal silicon wafer or a P-type single crystal silicon wafer, and the doping concentration of the N-type single crystal silicon wafer or the P-type single crystal silicon wafer is less than 1×10 15 cm -3 .

9. The back contact solar cell according to claim 7, characterized in that: The width of the N-type doping layer is 1 to 5 times the width of the P-type doping layer.

10. The back contact solar cell according to claim 9, characterized in that: The width of the N-type doping layer is 1.4 to 3.2 times the width of the P-type doping layer.

11. The back contact solar cell according to claim 7, characterized in that: The width of the P-type doping layer is 100 μm to 900 μm.

12. The back contact solar cell according to claim 11, characterized in that: The width of the P-type doping layer is 200 μm to 500 μm.

13. The back contact solar cell according to claim 7, characterized in that: An isolation region is provided between adjacent N-type doping layers and P-type doping layers to separate the two. The sum of the widths of a single N-type doping layer, two isolation regions and a single P-type doping layer is 0.3 mm to 3 mm.

14. The back contact solar cell according to claim 13, characterized in that: The sum of the widths of the single N-type doping layer, the two isolation regions and the single P-type doping layer is 0.5 mm to 1.6 mm.

15. The back contact solar cell according to claim 1, characterized in that: The sheet resistance of the P-type doping layer is greater than the sheet resistance of the N-type doping layer.

16. The back contact solar cell according to claim 15, characterized in that: The square resistance of the P-type doping layer is 1.5 to 10 times that of the N-type doping layer.

17. The back contact solar cell according to claim 15, characterized in that: The sheet resistance of the N-type doped layer is 26 ohm / sq to 150 ohm / sq, and the sheet resistance of the P-type doped layer is 80 ohm / sq to 400 ohm / sq.

18. The back contact solar cell according to claim 17, characterized in that: The sheet resistance of the N-type doped layer is 35 ohm / sq to 120 ohm / sq, and the sheet resistance of the P-type doped layer is 90 ohm / sq to 350 ohm / sq.

19. The back contact solar cell according to claim 18, characterized in that: The sheet resistance of the N-type doped layer is 35 ohm / sq to 80 ohm / sq, and the sheet resistance of the P-type doped layer is 90 ohm / sq to 220 ohm / sq.

20. The back contact solar cell according to claim 1, characterized in that: A passivation layer is also provided on the backlight surface, and the passivation layer is provided on the outside of the N-type doped layer and the P-type doped layer, and the passivation layer is provided with a first window and a second window, and a metal gate line is provided outside the passivation layer, and the metal gate line at least partially extends into the first window and contacts with the N-type doped layer, and the metal gate line at least partially extends into the second window and contacts with the P-type doped layer.

21. A battery assembly, characterized in that: Comprising a back-contact solar cell according to any one of claims 1 to 20.

22. A photovoltaic system, characterized in that: A battery assembly comprising the battery assembly of claim 21.

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