Patent ID: 12199195

The accompanying drawings herein are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

DETAILED DESCRIPTION

In order to better understand the technical solution of the present disclosure, embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

It is to be made clear that the described embodiments are only some rather than all of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present disclosure without creative efforts fall within the protection scope of the present disclosure.

The terms used in the embodiments of the present disclosure are intended only to describe particular embodiments and are not intended to limit the present disclosure. As used in the embodiments of the present disclosure and the appended claims, the singular forms of “a/an”, “the”, and “said” are intended to include plural forms, unless otherwise clearly specified by the context.

It is to be understood that the term “and/or” used herein is merely an association relationship describing associated objects, indicating that three relationships may exist. For example, A and/or B indicates that there are three cases of A alone, A and B together, and B alone. In addition, the character “/” herein generally means that associated objects before and after it are in an “or” relationship.

It is to be noted that the location terms such as “above”, “below”, “left”, and “right” described in the embodiments of the present disclosure are described with reference to the angles shown in the accompanying drawings, and should not be construed as limitations on the embodiments of the present disclosure. In addition, in the context, it is to be further understood that, when one element is referred to as being connected “above” or “below” another element, the one element may be directly connected “above” or “below” another element, or connected “above” or “below” another element via an intermediate element.

Embodiments of the present disclosure provide a photovoltaic module. As shown inFIG.1, the photovoltaic module includes glass10, a first packaging adhesive film20, a solar cell string30, a second packaging adhesive film40, and a back sheet50arranged successively along a thickness direction thereof. As shown inFIG.2andFIG.3, the solar cell string30includes solder strips301and a plurality of solar cells302. The solder strips301are configured to connect adjacent solar cells302. The solar cells302include a first direction X, a second direction Y, and a third direction Z perpendicular in pairs. The first direction X is a width direction of the solar cell302, the second direction Y is a length direction of the solar cell302, and the third direction Z is a thickness direction of the solar cell302. The plurality of solar cells302are spaced apart along the first direction X and/or the second direction Y For ease of description, in the embodiments of the present disclosure, the solar cells302staggered along the first direction X are denoted as first solar cells and second solar cells respectively. That is, the first solar cells and the second solar cells are connected through the solder strips301.

The first packaging adhesive film20and the second packaging adhesive film40may both be polyolefin elastomer (POE) adhesive films. POE is an ethylene octene copolymer, which is composed of saturated fat chains, and has characteristics of good weather resistance, UV aging resistance, excellent heat resistance, low temperature resistance, a wide range of use temperatures, good light transmittance, excellent electrical insulation, high cost performance, and easy manufacturing. Ethylene vinyl acetate (EVA) adhesive films may also be used. The EVA adhesive film is the most common adhesive film, which is mainly composed of EVA, a small amount of crosslinking agent, assistant crosslinker, anti-aging agent, and other functional additives. EVA is prepared by copolymerization of two monomers, and ethylene chain breaking is relatively stable.

The solar cells302may be half-cut solar cells. The use of the half solar cells can reduce resistance of the solar cells302, thereby reducing resistance loss of the photovoltaic module. As shown inFIG.3andFIG.4, the solar cell302includes a substrate1. Along the third direction Z, the substrate1has a first surface (not marked in the figure) and a second surface (not marked in the figure) arranged opposite to each other. The first surface is located on a side of the photovoltaic module facing the sunlight. The second surface is located on a side of the photovoltaic module facing away from the sunlight. The substrate1may be made of a silicon substrate material. The silicon substrate material may include one or more of monocrystalline silicon, polycrystalline silicon, amorphous silicon, and microcrystalline silicon. The substrate1may be an N-type semiconductor or a P-type semiconductor. Specific materials and types of the substrate1are not limited in the present disclosure. The embodiments of the present disclosure are based on an example in which the substrate1is an N-type silicon substrate.

The first surface and/or the second surface of the substrate1is provided with a textured surface (not marked in the figure). The textured surface has a light trapping effect, which can reduce reflectivity of a surface of the substrate1to less than 10%, thereby improving short-circuit current and conversion efficiency of the solar cell302. The second surface is subjected to passivation treatment, or the first surface and the second surface are both subjected to passivation treatment, to form a passivation layer7. The passivation layer7has functions of light antireflection and surface passivation. At the same time, doping layers8having different polarities are arranged on the second surface. For example, PN junctions are obtained by diffusion of boron sources and phosphorus sources.

The first surface and/or the second surface of the substrate1is provided with first busbars2and second busbars3extending along the first direction X and first fingers4and second fingers5arranged on the substrate1and extending along the second direction Y The first busbars2and the second busbars3are alternately arranged along the second direction Y and have opposite polarities. For example, the first busbars2are positive electrodes, while the second busbars3are negative electrodes. Alternatively, the first busbars2are negative electrodes, while the second busbars3are positive electrodes. The first fingers4and the second fingers5are alternately arranged along the first direction X. The first fingers4are connected to the first busbars2, and the second fingers5are connected to the second busbars3. Moreover, the first fingers4have a same polarity as the first busbars2, and the second fingers5have a same polarity as the second busbars3.

As shown inFIG.3, along the first direction X, the first busbars2on the first solar cells and the second busbars3on the second solar cells are located on a same extension line, and the second busbars3on the first solar cells and the first busbars2on the second solar cells are located on a same extension line. That is, the first busbars2of the first solar cells and the second busbars3of the second solar cells adjacent thereto are directly connected through the solder strip301, and the second busbars3of the first solar cells and the first busbars2of the second solar cells adjacent thereto are directly connected through the solder strip301, which effectively avoids warpage of the solar cell302and prevent hidden crack problems caused by excessively great stress.

In some embodiments, the first surface and the second surface are both provided with the first busbars2, the second busbars3, the first fingers4, and the second fingers5, and the solder strips301have one part connected to second surfaces of the solar cells302and the other part bending and extending and connected to first surfaces of the solar cells302adjacent thereto.

In some other embodiments, as shown inFIG.2,FIG.3, andFIG.8toFIG.13, the first busbars2, the second busbars3, the first fingers4, the second fingers5, and the solder strips301are all arranged on the second surface. In this case, the photovoltaic module is an IBC. That is, the solder strips301are respectively connected to second surfaces of two adjacent solar cells302, so as to reduce shielding of the first surface by the first busbars2, the second busbars3, the first fingers4, the second fingers5, and the solder strips301, thereby increasing the contact area between the first surface and the sunlight and thus improving photoelectric conversion efficiency of the photovoltaic module.

In the present disclosure, for example, the first busbars2, the second busbars3, the first fingers4, the second fingers5, and the solder strips301are all arranged on the second surface. That is, the photovoltaic module is an IBC solar cell.

In addition, the first busbars2and the second busbars3do not penetrate the passivation layer7. That is, the first busbars2and the second busbars3are directly printed on the passivation layer7. Alternatively, the first busbars2and the second busbars3penetrate the passivation layer7to contact the substrate1. The first fingers4and the second fingers5may be directly printed on the substrate1. That is, the first fingers4and the second fingers5penetrate the passivation layer7to directly contact the doping layer8.

Along the third direction Z, heights H1 of the first busbars2satisfy: 15 μm≤H1≤25 μm, and/or heights H2 of the second busbars3satisfy: 15 μm≤H2≤25 μm; and/or heights H3 of the first fingers4satisfy: 15 μm≤H3≤25 μm, and/or heights H4 of the second fingers5satisfy: 15 μm≤H4≤25 μm.

If the heights of the first busbars2and/or the second busbars3are less than 15 μm, it is not conducive for the first busbars2and the second busbars3to collect carriers, thereby having more influence on the photoelectric conversion efficiency of the photovoltaic module. If the heights of the first busbars2and/or the second busbars3are greater than 25 μm, the soldering tension may be affected. Therefore, 15 μm≤H1≤25 μm and 15 μm≤H2≤25 μm are conducive for the first busbars2and the second busbars3to collect carriers, which improves the photoelectric conversion efficiency of the photovoltaic module and is also conducive to the soldering tension between the solar cell302and the solder strip301. For example, the heights of the first busbars2and/or the second busbars3may be 15 μm, 20 μm, or 25 μm.

If the heights of the first fingers4and/or the second fingers5are less than 15 μm, it is not conducive for the first fingers4and the second fingers5to collect carriers, thereby affecting the photoelectric conversion efficiency of the photovoltaic module. If the heights of the first fingers4and/or the second fingers5are greater than 25 μm, manufacturing costs of the first fingers4and the second fingers5are increased. Therefore, 15 μm≤H3≤25 μm and 15 μm H4≤25 μm can reduce the manufacturing costs of the first fingers4and the second fingers5, and can also improve the photoelectric conversion efficiency of the photovoltaic module. For example, the heights of the first fingers4and/or the second fingers5may be 15 μm, 20 μm, or 25 μm.

Widths of the first busbars2and/or the second busbars3along the second direction Y may be in a range of 30 μm to 60 μm, and widths of the first fingers4and/or the second fingers5along the first direction X may be in a range of 20 μm to 40 μm, which can reduce shielding of an effective area of the photovoltaic module by the first busbars2, the second busbars3, the first fingers4, and the second fingers5, thereby improving the photoelectric conversion efficiency of the photovoltaic module, reducing manufacturing costs of the first busbars2, the second busbars3, the first fingers4, and the second fingers5, and improving reliability of the first busbars2and the second busbars3.

As shown inFIG.5,FIG.6, andFIG.8toFIG.14, the substrate1is provided with a plurality of busbar pits11, and the doping layers8may be located in the busbar pits11. The plurality of busbar pits11are spaced apart long the second direction Y, and at least part of the first busbars2and at least part of the second busbars3are located in the busbar pits11, which reduces distances from minority carriers to the doping layers8, thereby increasing an open-circuit voltage of the solar cell302and thus improving the photoelectric conversion efficiency of the photovoltaic module.

When the solder strips301are connected to adjacent solar cells302, at least part of the solder strips301are located in the busbar pits11, which is conducive to improving the soldering tension between the solar cells302and the solder strips301, thereby improving stability of the connection between the solder strips301and the solar cells302.

In one or more embodiments, since the first fingers4are not in contact with the second busbars3with a different polarity, the first fingers4are not required to enter the busbar pits11printed with the second busbars3. Since the first fingers4are in contact with the first busbars2with the same polarity, the first fingers4can enter the busbar pits11printed with the first busbars2and connected to the first busbars2. Since the second fingers5are not in contact with the first busbars2with the different polarity, the second fingers5are not required to enter the busbar pits11printed with the first busbars2. Since the second fingers5are in contact with the second busbars3with the same polarity, the second fingers5can enter the busbar pits11printed with the second busbars3and be connected to the second busbars3.

Along the third direction Z, a thickness H of the substrate1satisfies: 160 μm≤H≤230 μm. For example, the thickness of the substrate1in the third direction Z may be 160 μm, 179 μm, 186 μm, 200 μm, 226 μm, or 230 μm.

In some embodiments, since the substrate1is provided with the busbar pits11, if the thickness of the substrate1is small, that is, H≤160 μm, the substrate1is prone to hidden cracks near the busbar pits11. If the thickness of the substrate1is large, that is, H>230 μm, costs of the solar cell302are increased, and an overall thickness of the photovoltaic module is increased. Therefore, 160 μm≤H≤230 μm can reduce the overall thickness of the photovoltaic module to reduce manufacturing costs, increase structural strength of the substrate1, prolong the service life of the photovoltaic module, and improve operation stability of the photovoltaic module.

Along the third direction Z, depths h1 of the busbar pits11satisfy: 30 μm≤h1≤50 μm.

In some embodiments, if the depths of the busbar pits11are less than 30 μm, it is not conducive to the soldering tension between the solar cell302and the solder strip301. If the depths of the busbar pits11are greater than 50 μm, the risk of hidden cracks of the solar cell302may be increased. Therefore, 30 μm≤h1≤50 μm can reduce the risk of hidden cracks of the solar cell302and be conducive to improving the soldering tension between the solar cell302and the solder strip301. For example, the depths of the busbar pits11may be 30 μm, 35 μm, 40 μm, 45 μm, or 50 μm.

Along the third direction Z, ratios of the depths of the busbar pits11to the heights of the first busbars2range from 10:3 to 6:5, and/or ratios of the depths of the busbar pits11to the heights of the second busbars3range from 10:3 to 6:5.

The ratios of the depths of the busbar pits11to the heights of the first busbars2may be in a large range of 10:1 to 10:9 and a small range of 5:2 to 5:3. In one or more embodiments, along the third direction Z, the ratios of the depths of the busbar pits11to the heights of the first busbars2are in a range of 10:3 to 6:5, such as 10:3, 2:1, 7:3, 9:4, 5:2, or 6:5. Additionally or alternatively, the ratios of the depths of the busbar pits11to the heights of the second busbars3may be in a large range of 10:1 to 10:9 and a small range of 5:2 to 5:3. In one or more embodiments, along the third direction Z, the ratios of the depths of the busbar pits11to the heights of the second busbars3are in a range of 10:3 to 6:5, such as 2:1, 7:3, 9:4, 5:2, or 6:5. The ratios of the depths of the busbar pits11to the heights of the first busbars2and the ratios of the depths of the busbar pits11to the heights of the second busbars3may be the same or different.

In certain embodiments, the depths of the busbar pits11along the third direction Z range from 30 μm to 50 μm. “Along the third direction Z, ratios of the depths of the busbar pits11to the heights of the first busbars2and/or the second busbars3range from 10:3 to 6:5” is conducive to improving soldering tension between the solar cell302and electrode pads6and reduces the risk of hidden cracks of the solar cell302. At the same time, due to a decrease in the distances from the minority carriers to the doping layers8, the open-circuit voltage of the IBC is increased, thereby improving photoelectric conversion efficiency of the IBC.

In the present disclosure, the depths of the busbar pits along the thickness direction of the substrate range from 30 μm to 50 μm. Along the thickness direction of the substrate, the ratios of the depths of the busbar pits to the heights of the first busbars and/or the second busbars range from 10:3 to 6:5. When the solder strips are connected to the solar cells, part of the solder strips can extend into the busbar pits, which is conducive to improving soldering tension between the solar cells and the solder strips and reduces risks of hidden cracks of the solar cells, thereby improving operation stability of the photovoltaic module.

In addition, cross sections of the busbar pits11along the second direction Y are in shapes of rectangles, semi-circles, triangles, arcs, trapezoids, or other transformational structures. The shapes of the cross sections of the busbar pits11are not limited in the embodiments of the present disclosure. The embodiments of the present disclosure are based on an example in which cross sections of the busbar pits11along the second direction Y are semi-circles.

In one or more embodiments, as shown inFIG.4, along the first direction X, the electrode pads6are spaced apart on both the first busbars2and the second busbars3, and the solder strip301is fixedly connected with the solar cell302through the electrode pads6. A number of the electrode pads6on one first busbar2and one second busbar3is no less than 3. In one or more embodiments, the number of the electrode pads6may be 4 or more, such as 5 or 6. The specific number of the electrode pads6is not limited in the embodiments of the present disclosure.

In some embodiments, as shown inFIG.4andFIG.5, the busbar pits11extend along the first direction X, and the first busbars2and the second busbars3are arranged in the busbar pits11as a whole. As shown inFIG.8andFIG.9, the solder strip301is directly clamped into the busbar pits11and connected to the first busbars2and the second busbars3. The busbar pits11extend along the first direction X, which simplifies the manufacturing procedure of the busbar pits11, thereby reducing manufacturing costs of the busbar pits11. The solder strip301is clamped, in entirety, into the busbar pits11. When the solder strip301moves relative to the solar cell302, the solder strip301can abut against sidewalls of the busbar pits11to limit an installation position of the solder strip301, which reduces installation difficulty of the solder strip301, thereby improving stability of the connection between the solder strip301and the solar cell302and reducing the risk of deflection of the solder strip301. Taking the solder strip301on the first busbars2as an example, risks of contact and electrical connection of the solder strip301with the second fingers5are reduced. That is, the risk of short circuit of the solar cell302caused by series connection between the first fingers4and the second fingers5through the first busbars2and the solder strip301is reduced, thereby improving the operation stability and service life of the solar cell302.

In some other embodiments, as shown inFIG.4andFIG.6, the plurality of busbar pits11are spaced apart along the first direction X, and part of the first busbars2and part of the second busbars3are located in the busbar pits11. The busbar pits11are spaced apart along the first direction X, which reduces an etching area of the substrate1, thereby helping to improve structural strength of the substrate1. In one or more embodiments, as shown inFIG.10,FIG.11,FIG.12, andFIG.13, the solder strip301includes body portions301aand protruding portions301b. At least part of the protruding portions301bare located in the busbar pits11. When the solder strip301moves relative to the solar cell302, the protruding portions301bcan abut against sidewalls of the busbar pits11to limit an installation position of the solder strip301, which reduces the risk of short circuit of the solar cell302caused by series connection between the first fingers4and the second fingers5through the first busbars2and the solder strip301, thereby improving the operation stability and service life of the solar cell302.

In some embodiments, a number of the busbar pits11is no less than that of the protruding portions301b, so as to facilitate adjustment of the installation position of the solder strip301. In addition, profile shapes of cross sections of the protruding portions301bare not limited to rectangles, cylinders, cones, spheres, and the like. The profile shapes of the protruding portions301bare not limited in the embodiments of the present disclosure.

In one or more embodiments, the busbar pits11include first pits (not marked in the figure) and second pits (not marked in the figure) spaced apart along the first direction X. The first pits are arranged opposite to the electrode pads6along the third direction Z, and depths of the first pits are greater than the second pits.

In some embodiments, the electrode pads6are located at the first pits, and the depths of the first pits are greater than the second pits. After the solder strip301is connected to the solar cell302, the risk of unevenness of surfaces of the solder strip301facing away from the solar cell302caused by protrusion of the solder strip301at the electrode pads6, thereby facilitating the installation and use of the photovoltaic module. Shallow second recesses are arranged in a non-electrode-pad region, which can increase numbers of the protruding portions301band the busbar pits11, thereby increasing positions of clamping between the solder strip301and the solar cell302, reducing the risk of short circuit of the solar cell302caused by local deformation of the solder strip301, and further improving the operation stability and service life of the solar cell302.

One or more second pits may be arranged between two adjacent first pits, and one or more first pits may be arranged between two adjacent second pits. Specific distribution manners of the first pits and the second pits are not limited in the present disclosure. Profile shapes of the first pits and the second pits may be the same or different. Specific structures of the first pits and the second pits are not limited in the present disclosure.

In addition, shapes of cross sections of the body portions301ainclude, but are not limited to, quadrangles, circles, or other transformational structures. Specific structures of the body portions301aare not limited in the present disclosure.

Thickness dimensions h3 of the body portions301ain the third direction Z satisfy: 0.1 mm≤h3≤0.3 mm. For example, thicknesses of the body portions301ain the third direction Z may be 0.1 mm, 0.15 mm, 0.21 mm, 0.26 mm, or 0.3 mm.

In some embodiments, if the thicknesses of the body portions301aare small, i.e., h3≤0.1 mm, the solder strip301may be cracked and damaged during manufacturing, transportation, and installation, and at the same time, there is a risk that the device cannot solder the solder strip301and the electrode pads6. If the thicknesses of the body portions301aare large, i.e., h3>0.3 mm, the solder strip301easily deviates from a preset installation position under external force, that is, the solder strip301is under greater stress, and at the same time, costs of the solder strip301are increased. Therefore, 0.1 mm≤h3≤0.3 mm can facilitate the device to solder the solder strip301and the electrode pads6, reduce costs of the solder strip301, improve structural strength of the body portions301a, prolong the service life of the solder strip301, improve operation stability of the solder strip301, reduce the stress of the solder strip301, and improve stability of the soldering.

Heights h4 of the protruding portions301bin the third direction Z satisfy: 35 μm≤h4≤65 μm; and/or the depths h1 of the busbar pits11in the third direction Z satisfy: 35 μm≤h1≤45 μm. For example, the heights of the protruding portions301bin the third direction Z may be 35 μm, 42 μm, 51 μm, or 65 μm; and the depths of the busbar pits11in the third direction Z may be 35 μm, 39 μm, 43 μm, or 45 μm.

In a high-temperature environment, the solder strip301may expand due to thermal expansion and cold contraction. If the heights of the protruding portions301bare large, that is, h4>65 μm, the protruding portions301bmay exert force on the solar cell302, causing damages to the solar cell302. If the heights of the protruding portions301bare small, that is, h4≤35 μm, depths of the connection between the protruding portions301band the busbar pits11are small. During the installation and fixation, there is a risk that oxygen may enter gaps between the protruding portions301band the busbar pits11to cause oxidization of the solar cell302. Therefore, 35 μm≤h4≤65 μm can reduce the risk of damages to the solar cell302by the solder strip301, and can also reduce the risk of oxidization of the solar cell302, thereby prolonging the service life of the solar cell302and improving operation stability of the solar cell302.

If the depths of the busbar pits11are small, that is, h1≤35 μm, there is a risk that the protruding portions301bare detached from the busbar pits11. If the depths of the busbar pits11are large, that is, h1>45 μm, the strength of the substrate1is reduced, and there is a risk that the substrate1is damaged during subsequent manufacturing, transportation, and use of the substrate1. Therefore, 35 μm≤h1≤45 μm can improve stability of the connection between the protruding portions301band the busbar pits11, thereby improving accuracy of the installation position of the solder strip301, and can reduce risks of defects such as hidden cracks of the solar cell302, thereby prolonging the service life of the solar cell302and improving operation stability of the solar cell302.

In any one of the above embodiments, 15% to 25% of the solder strip301is located in the busbar pits11. If less than 15% of the solder strip301is in the busbar pits11, contact areas between the solder strip301and the busbar pits11are excessively small, and the soldering tension is not ideal. If more than 25% of the solder strip301is in the busbar pits11, the solar cell302is prone to hidden cracks. Therefore, 15% to 25% of the solder strip301is located in the busbar pits, which can prevent excessively small contact areas between the solder strip301and the busbar pits11, help to increase soldering tension between the solar cell302and the solder strip301, and reduce the hidden crack rate of the solar cell302.

As shown inFIG.4toFIG.7, the substrate1is further provided with a plurality of finger pits12spaced apart along the first direction X, and at least part of the first fingers4and at least part of the second fingers5are located in the finger pits12. Since the first surface of the substrate1is provided with no electrodes, photogenerated electrons on the first surface are required to be collected through the electrodes on the second surface (the first fingers4, the second fingers5, the first busbars2, and/or the second busbars3). Through the finger pits12, paths of the photogenerated electrons can be reduced within a certain range and recombinations can be reduced, thereby improving the photoelectric conversion efficiency of the solar cell302.

In some embodiments, the finger pits12extend along the second direction Y, and the first fingers4and the second fingers5are wholly arranged in the finger pits12. The finger pits12extend along the second direction Y, which simplifies the manufacturing procedure of the finger pits12, thereby reducing manufacturing costs of the finger pits12.

In some other embodiments, the plurality of finger pits12are spaced apart along the second direction Y, and part of the first fingers4and part of the second fingers5are located in the busbar pits11. The finger pits12are spaced apart along the second direction Y, which reduces an etching area of the substrate1, thereby helping to improve structural strength of the substrate1.

In one or more embodiments, along the third direction Z, the depths of the busbar pits11are greater than the finger pits12, which helps to embed part of the solder strip301into the busbar pits11and further increases the soldering tension.

Along the third direction Z, the depths h2 of the finger pits12satisfy: 25 μm≤h2≤35 μm.

In some embodiments, if the depths of the finger pits12are less than 25 μm, the finger pits12cannot be formed, and the efficiency of the solar cell302cannot be improved. If the depths of the finger pits12are greater than 35 μm, the substrate1is excessively thin, which may lead to an increase in the hidden crack rate. Therefore, 25 μm≤h2≤35 μm can reduce the hidden crack rate of the solar cell302and help to form the finger pits12. For example, the depths of the finger pits12may be 25 μm, 28 μm, 31 μm, or 35 μm.

Widths of the busbar pits11along the second direction are W1, widths of the finger pits12along the first direction are W2, and W1>W2. The widths of the busbar pits11along the second direction Y are greater than the widths of the finger pits12along the first direction X, which can effectively increase the soldering tension. In other words, in order to enable part of the solder strip301to be embedded into the busbar pits11, the widths and depths thereof are greater than those of the finger pits12, so as to reduce a risk that the solder strip301is installed in the finger bits12by mistake.

The widths W1 of the busbar pits11along the second direction satisfy: 40 μm≤W1≤70 μm; and/or the widths W2 of the finger pits12along the first direction satisfy: 25 μm≤W2≤35 μm.

If the widths of the busbar pits11are less than 40 μm, it is not conducive to improving the soldering tension. If the widths of the busbar pits11are greater than 70 μm, the risk of hidden cracks of the solar cell302is increased. Therefore, 40 μm≤W1≤70 m is more conducive to the soldering tension and reduces the risk of hidden cracks of the solar cell302. For example, the widths of the busbar pits11may be 40 μm, 50 μm, 60 μm, or 70 μm.

If the widths of the finger pits12along the first direction X are less than 25 μm, the efficiency of the solar cell302cannot be improved. If the widths of the finger pits12along the first direction X are greater than 35 μm, the hidden crack rate of the solar cell302is increased. Therefore, 25 μm≤W2≤35 μm can improve the efficiency of the solar cell302and reduce the hidden crack rate of the solar cell302. For example, the widths of the finger pits12may be 25 μm, 28 μm, 31 μm, or 35 μm.

Based on the photovoltaic module in any one of the above embodiments, taking an IBC solar cell as an example, the present disclosure provides a method for manufacturing a photovoltaic module. As shown inFIG.14, the method for manufacturing a photovoltaic module includes: etching the busbar pits11on the second surface of the substrate1; doping the substrate1, and forming n+ doping regions and p+ doping regions arranged alternately after the doping; manufacturing a metal electrode on the second surface, the metal electrode includes first busbars2, second busbars3, first fingers4, second fingers5, and electrode pads6, the first fingers4and the second fingers5are in ohmic contact with the n+ doping regions and the p+ doping regions, and at least part of the first busbars2and the second busbars3are located in the busbar pits11; placing the solder strips301on the solar cells302, part of the solder strips301extending into the busbar pits11; and fixing the solder strips301and the solar cells302through the electrode pads6.

In one or more embodiments, prior to the step of doping the substrate1, and forming n+ doping regions and p+ doping regions arranged alternately after the doping, the method for manufacturing a photovoltaic module further includes: etching the finger pits12on the second surface.

Based on the above, the method for manufacturing a photovoltaic module according to the embodiments of the present disclosure is: etching the busbar pits11and the finger pits12on the second surface of the substrate1by laser etching or mechanical etching; cleaning the substrate1to remove damaged structures after the etching; texturing the first surface and the second surface of the substrate1to form textured surfaces, the texturing is intended to form uneven structures on originally bright surfaces of the substrate1through chemical reaction to extend a propagation path of light on the surfaces thereof, so as to improve light absorption of the solar cells302; doping the second surface of the substrate1, and forming a doping layer8after completion of the doping, wherein the doping layer8includes n+ doping regions and p+ doping regions arranged alternately, for example, PN junctions are obtained by diffusion of boron sources and phosphorus sources; coating the first surface of the substrate1by using a plasma enhanced chemical vapor deposition (PECVD) device, to form an antireflection film which can reduce reflection of the light; depositing a layer of SiNx (silicon nitride) on the second surface of the substrate1by using the PECVD device, to form a passivation layer7having functions of surface passivation and antireflection; manufacturing a metal electrode on the second surface of the substrate1, the metal electrode includes first busbars2, second busbars3, first fingers4, second fingers5, and electrode pads6, the first fingers4and the second fingers5being in ohmic contact with the n+ doping regions and the p+ doping regions on the second surface, at least part of the first busbars2and the second busbars3are located in the busbar pits11, and at least part of the first fingers4and at least part of the second fingers5are located in the finger pits12; placing the solder strips301on the solar cells302to cause part of the solder strips301to extend into the busbar pits11; soldering the solder strips301and the solar cells302at the electrode pads6to form the solar cell string30; and laminating and fixing the glass10, the first packaging adhesive film20, the solar cell string30, the second packaging adhesive film40, and the back sheet50.

In some embodiments, the manufacturing a metal electrode may involve printing silver aluminum paste on the p+ doping regions of the second surface and silver paste on the n+ doping regions of the second side after treatment by screen printing. The first busbars2, the second busbars3, and the electrode pads6may be directly printed on the passivation layer7of the second surface without penetrating the substrate1. Alternatively, the first busbars2, the second busbars3, the first fingers4, and the second fingers5may penetrate the passivation layer7to be printed on the doping layer8, and then are sintered.

In some embodiments, the use of the formed busbar pits11and finger pits12can increase the soldering tension between the solder cell302and the solder strip301and can significantly reduce distances from the minority carriers to the doping layers8, which increases the open-circuit voltage of the IBC, thereby improving efficiency of the IBC.

The above are merely some embodiments of the present disclosure, and are not intended to limit the present disclosure. For those skilled in the art, the present disclosure may be subject to various modifications and changes. Any modification, equivalent replacement, improvement and the like within the spirit and principle of the present disclosure all fall within the protection scope of the present disclosure.