Back contact type solar cell and photovoltaic module

Abstract

The invention provides a back contact type solar cell and a photovoltaic module, and the back contact type solar cell comprises a substrate which is provided with two first edges which are oppositely arranged, and each first edge extends along a first direction; the electrode layer is located on the substrate, and the electrode layer comprises a plurality of first current collection electrodes which are alternately arrayed at intervals in the first direction with different polarities and extend in the second direction perpendicular to the first direction; the multiple bus electrodes are alternately arranged at intervals in the second direction with different polarities and extend in the first direction, the bus electrodes are connected with the first current collection electrodes with the same polarity and electrically isolated from the first current collection electrodes with different polarities, and the bus electrode closest to the first edge serves as the first bus electrode; and a second collector electrode extending in the first direction and located between the first bus electrode and the first edge, the second collector electrode having a polarity different from that of the first bus electrode, and being connected to at least one first collector electrode having the same polarity.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular, to a back-contact solar cell and a photovoltaic module. Background Art

[0002] Back-contact solar cells generally have P-region collecting electrodes and N-region collecting electrodes printed on the back of the cell, which are then connected to the bus electrode to effectively collect current; and the front of the cell is not blocked by metal electrodes, which improves light utilization. Therefore, back-contact solar cells are a type of solar cell with relatively high conversion efficiency.

[0003] In back-contact solar cells, the structural design of the back electrode is closely related to the carrier collection efficiency, and there is still room for improvement. For example, there is a large gap between the edge bus electrode and the edge of the cell, resulting in loss of carrier collection. Improvements to this can improve cell efficiency. Summary of the invention

[0004] In view of this, in order to at least partially solve at least one of the above-mentioned technical problems, the present application provides a back-contact solar cell and a photovoltaic module.

[0005] In order to achieve the above purpose, the technical solution of this application is as follows:

[0006] According to an embodiment of one aspect of the present application, there is provided a back-contact solar cell, comprising: a substrate having two first edges arranged opposite to each other and each extending along a first direction; an electrode layer located on the substrate, the electrode layer comprising: a plurality of first collecting electrodes arranged in an array alternately spaced with different polarities in the first direction and each extending along a second direction intersecting the first direction; at least two bus electrodes each extending along the first direction, the bus electrodes being connected to first collecting electrodes of the same polarity and electrically isolated from first collecting electrodes of different polarities, wherein the bus electrode closest to the first edge is the first bus electrode; and a second collecting electrode extending along the first direction and located between the first bus electrode and the first edge, the second collecting electrode having a polarity different from that of the first bus electrode and being connected to at least one first collecting electrode of the same polarity.

[0007] According to another embodiment of the present application, a photovoltaic assembly is provided, comprising: a plurality of the above-mentioned back-contact solar cells connected in series to form a solar cell string; and a packaging structure disposed around the periphery of the above-mentioned solar cell string.

[0008] According to the embodiments of the present application, the back-contact solar cell provided by the present application arranges a second collecting electrode with a polarity different from that of the first bus electrode between the first bus electrode located at the edge and the edge of the battery. At least part of the edge carriers generated at the edge of the battery no longer need to migrate to the first collecting electrode with a polarity different from that of the first bus electrode for collection, but can be effectively collected by the second collecting electrode located at the edge of the battery, thereby reducing the possibility of edge carriers being recombined on the collection path, thereby effectively improving the carrier collection efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and other objects, features and advantages of the present application will become more apparent through the following description of the embodiments of the present application with reference to the accompanying drawings, in which:

[0010] Figure 1 is a partial schematic diagram of a back-contact solar cell in the related art;

[0011] Figure 2 is a partial schematic diagram of a top view of a back-contact solar cell according to an exemplary embodiment of the present application;

[0012] Figure 3 is a schematic diagram of the position of a second current collecting electrode according to an exemplary embodiment of the present application;

[0013] Figure 4 is a schematic diagram of the arrangement of electrode layers on the surfaces of both sides of the separation region according to another exemplary embodiment of the present application;

[0014] Figure 5A is a partial schematic diagram of a cross-sectional view of a back-contact solar cell according to an exemplary embodiment of the present application;

[0015] Figure 5B is a partial schematic diagram of a cross-sectional view of a back-contact solar cell according to another exemplary embodiment of the present application;

[0016] Figure 6 A schematic diagram of the positional relationship between a target semiconductor region and a first collector electrode according to an exemplary embodiment of the present application;

[0017] Figure 7 is a partial schematic diagram of a second collector electrode according to another exemplary embodiment of the present application.

[0018] In the drawings, the meanings of the reference numerals are as follows:

[0019] 100, base;

[0020] 110. Electrode area;

[0021] 120. Separation area;

[0022] 210, a first semiconductor region;

[0023] 220, a second semiconductor region;

[0024] 221, edge semiconductor region;

[0025] 222, target semiconductor region;

[0026] 230, a third semiconductor region;

[0027] 303, a first contact pad;

[0028] 311, first edge;

[0029] 312, second edge;

[0030] 320, a first current collecting electrode;

[0031] 330, busbar electrode;

[0032] 331, a first bus electrode;

[0033] 332. a second bus electrode;

[0034] 340. A second collecting electrode. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0036] The terms used herein are only for describing specific embodiments and are not intended to limit the present application. The terms "including", "comprising", etc. used herein indicate the presence of features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components. All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0037] The relative position between two components (such as film layers or regions) mentioned in this application, such as "above", "upper" or "above", may refer to the direct contact between the two components, or may refer to the indirect contact between the two components. Similarly, the relative position between two components mentioned in this application, such as "below", "lower" or "below", may refer to the direct contact between the two components, or may refer to the indirect contact between the two components. For example, when one of the components (such as film layers or regions) is referred to as "on another component", it can be directly on the other component, or there may be other components between the two. On the other hand, when a component is referred to as "directly on another component", there is no component between the two. In addition, when one of the components is referred to as "on another component", the two have an up-and-down relationship in the top-view direction, and this component can be above or below the other component, so this up-and-down relationship depends on the orientation of the device.

[0038] Unless there are technical obstacles or contradictions, the various technical features disclosed in this application can be freely combined to form additional embodiments, and these additional embodiments are all within the scope of protection of this application. In a back-contact solar cell, the positive collector electrode and the negative collector electrode are respectively arranged on semiconductor regions of different conductivity types on the back of the battery, and then connected to a bus electrode of the same polarity, and / or other bus structures (such as welding strips, conductive backplanes, etc.) to collect the current generated by the battery. The back-contact solar cell can be a rectangular or square structure, and can include an odd or even number of bus electrodes, with the positive and negative bus electrodes distributed adjacently.

[0039] The working principle of solar cells is based on the photovoltaic effect of semiconductor PN junction. The so-called photovoltaic effect is an effect that when a semiconductor is exposed to light, the charge distribution state in the semiconductor changes, generating electromotive force and current. When sunlight or other light shines on the PN junction of a semiconductor, a voltage will appear on both sides of the PN junction, which is called photovoltaic voltage.

[0040] Therefore, the necessary conditions for the effective operation of solar cells are: ① There must be light irradiation, which can be monochromatic light, sunlight, or simulated sunlight; ② After photons are injected into the semiconductor, electron-hole pairs are excited, and they have a sufficiently long life, that is, they will not be recombined before separation; ③ There must be an electrostatic field under the action of the battery, and the electron-hole pairs are separated, with electrons concentrated on one side and holes on the other side (mostly). Solar cells use the electrostatic field of the PN junction to separate electron-hole pairs (the PN junction is the heart of the solar cell); ④ The separated electrons and holes are collected by electrodes and output outside the battery body.

[0041] In the process of realizing the concept of this application, it is found that the structural design of the back electrode is closely related to the carrier collection efficiency, and there is still room for improvement. For example, there is a large gap between the edge bus electrode and the edge of the cell, resulting in loss of carrier collection. Improvements to this can improve cell efficiency. For example, for the electrode area of ​​a back-contact solar cell, such as Figure 1 As shown in the figure, if electron-hole pairs are generated at the edge of the battery, the collection distance of holes is short, while the collection path of electrons is long. Therefore, during the collection process, electrons at the edge of the battery are easily recombined due to the long collection path, resulting in ineffective current generation.

[0042] Specifically, according to an embodiment of one aspect of the present application, a back-contact solar cell is provided. Figure 2 FIG. 1 is a partial schematic diagram of a top view of a back-contact solar cell according to an exemplary embodiment of the present application, wherein the dot-dash line indicates an omitted drawing. Figure 2 As shown, the back-contact solar cell provided in the embodiment of the present application includes a substrate and an electrode layer. The substrate has two first edges 311 arranged opposite to each other, each extending along a first direction a. The electrode layer is located on the substrate, and the electrode layer includes a plurality of first collector electrodes 320, at least two bus electrodes 330, and a second collector electrode 340. Among them, a plurality of first collecting electrodes 320 are arranged in an array alternately spaced with different polarities in a first direction a, and each extends along a second direction b intersecting the first direction a; at least two bus electrodes 330 each extend along the first direction a, the bus electrode 330 is connected to the first collecting electrode 320 of the same polarity, and is electrically isolated from the first collecting electrodes 320 of different polarities, and the bus electrode closest to the first edge 311 is the first bus electrode 331; and a second collecting electrode 340 extends along the first direction a and is located between the first bus electrode 331 and the first edge 311, the second collecting electrode 340 has a different polarity from the first bus electrode 331, and is connected to at least one first collecting electrode of the same polarity.

[0043] The back-contact solar cell provided in the embodiment of the present application can be for a cell with an odd number of bus electrodes, but is not limited thereto, and can also be for a cell with an even number of bus electrodes, which can effectively improve the carrier collection efficiency, and can also be provided with bus electrodes only adjacent to the edge of the cell, and the collector electrodes at other positions rely on other bus structures for current collection. Exemplarily, the specification of the back-contact solar cell can be 182*183.75mm, and can include 19 bus electrodes 330, the main grid distribution of the electrode area can be P1-N1-…-N9-P10, and each bus electrode can include 7 contact pads (PAD points).

[0044] According to an embodiment of the present application, "polarity" refers to a positive electrode or a negative electrode. Generally, an electrode for collecting electrons is a negative electrode, and an electrode for collecting holes is a positive electrode. The polarity of the first bus electrode 331 can be a positive electrode or a negative electrode. When the first bus electrode 331 is a positive electrode, the second collector electrode 340 is a negative electrode. When the first bus electrode 331 is a negative electrode, the second collector electrode 340 is a positive electrode.

[0045] According to an embodiment of the present application, the substrate may be an N-type or P-type semiconductor substrate. Specifically, the semiconductor substrate may be, for example, a crystalline silicon substrate, and further optionally, may be, for example, a semiconductor material selected from monocrystalline silicon, polycrystalline silicon, and microcrystalline silicon, preferably an N-type or P-type monocrystalline silicon substrate. The conversion efficiency of cells based on monocrystalline silicon substrates is higher than that of other types such as polycrystalline silicon cells. By introducing donor impurities such as phosphorus (P), arsenic (As) or antimony (Sb) into these semiconductor materials, an N-type silicon substrate is obtained, or by introducing acceptor impurities such as boron (B), aluminum (Al) or gallium (Ga) into these semiconductor materials, a P-type silicon substrate is obtained. Here, there are no excessive restrictions on the specific type of the substrate. In practical applications, technicians can select a suitable material as a substrate as needed.

[0046] According to an embodiment of the present application, the first collector electrode can be electrically isolated from the bus electrode 330 or other bus structure of different polarities in a variety of ways. For example, one is to set the first collector electrodes of different polarities into a discontinuous structure spaced apart along the second direction b, so that the bus electrode 330 or other bus structure passes through the disconnected portion formed by the first collector electrodes of different polarities, such as Figure 2 As shown; secondly, a first collector electrode with a continuous structure is adopted, and an insulating layer is provided between the overlapping parts of the bus electrode 330 or other bus structures and the first collector electrodes of different polarities.

[0047] According to the embodiments of the present application, during the collection process, the carriers at the edge of the battery are easily recombined due to the long collection path, resulting in the inability to effectively generate current. However, the present application can shorten the collection path of edge carriers by setting a second collector electrode with a different polarity from the first collector electrode between the first collector electrode at the edge and the edge of the battery, thereby reducing the possibility of edge carriers being recombined on the collection path, and effectively improving the carrier collection efficiency.

[0048] Generally, in solar cells, the minority carrier lifetime is shorter than that of majority carriers, which makes the minority carrier migration ability weaker than that of majority carriers, and makes it easier for recombination to occur due to the longer collection path. Therefore, the optimization of minority carrier collection efficiency is more conducive to improving battery efficiency. When considering improving the edge minority carrier collection efficiency, a second collector electrode can be set to collect minority carriers at the edge of the battery. In this case, the first bus electrode is used to collect majority carriers. Compared with setting the second collector electrode to collect majority carriers, this setting has a more significant effect on improving the battery carrier collection efficiency.

[0049] According to an embodiment of the present application, Figure 3 is a schematic diagram of the position of the second collector electrode according to an exemplary embodiment of the present application, such as Figure 2 and Figure 3 As shown, the distance between the side of the second collecting electrode 340 close to the first edge 311 and the first edge 311 is L1, and the distance between the adjacent sides of the second collecting electrode 340 and the first bus electrode 331 is L2, then the ratio of L1 to L2 is 1:4~4:1, for example, it can be 1:4, 2:4, 3:4, 1:1, 4:3, 3:2, 2:1, 3:1 or 4:1.

[0050] According to the embodiment of the present application, a second collector electrode is arranged between the first bus electrode and the edge of the cell, and the two can effectively collect carriers in different situations by changing their relative positions. For example, when the requirements for collecting electrons and holes are the same, the ratio of L1 to L2 can be selected to be 1:1. In other cases, the ratio of L1 to L2 can be selected according to actual needs.

[0051] According to an embodiment of the present application, the distance between the side of the first bus electrode 331 close to the first edge 311 and the first edge 311 is 0.3-1 mm, for example, it can be 0.3 mm, 0.32 mm, 0.4 mm, 0.45 mm, 0.47 mm, 0.5 mm, 0.52 mm, 0.54 mm, 0.55 mm, 0.57 mm, 0.59 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.96 mm or 1 mm. If the first bus electrode is too wide from the first edge, it will make it difficult to effectively collect the current at the edge. If it is too narrow, the current collection effect of the second collector electrode is limited, and the printing accuracy requirement is too high. In the case of setting a sufficient effective power generation area, the preferred range of the above distance can be 0.4-0.6 mm, or 0.5-0.6 mm.

[0052] According to the embodiments of the present application, Figure 2 and Figure 3As shown, the distance L2 between the adjacent sides of the second collector electrode 340 and the first bus electrode 331 is 0.07-0.30 mm, for example, it can be 0.07 mm, 0.08 mm, 0.09 mm, 0.10 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm, 0.15 mm, 0.17 mm, 0.20 mm, 0.22 mm, 0.25 mm, 0.27 mm or 0.30 mm. If the distance between the second collector electrode and the first bus electrode is too narrow, leakage is easy to occur, and if it is too wide, the transmission distance of the carriers on the first collector electrode and the second collector electrode is increased, which is not conducive to the improvement of the current collection effect. In the case of setting a sufficient effective power generation area, the preferred range of the above distance can be 0.07-0.15 mm.

[0053] According to an embodiment of the present application, the distance between the side of the second collector electrode 340 close to the first edge 311 and the first edge 311 can be 0.2-0.53 mm, for example, 0.2 mm, 0.22 mm, 0.25 mm, 0.28 mm, 0.30 mm, 0.32 mm, 0.35 mm, 0.37 mm, 0.40 mm, 0.42 mm, 0.45 mm, 0.48 mm, 0.50 mm or 0.53 mm. If the second collector electrode is too wide from the first edge, it will make it difficult to effectively collect the current at the edge. If it is too narrow, the current collection efficiency of the second collector electrode will be reduced, and the printing accuracy requirement will be too high.

[0054] According to the embodiment of the present application, the width of the bus electrode is determined according to different materials and actual needs, and the width may be, for example, 0.08-0.5 mm, and the material may be, for example, silver, aluminum or copper. Taking aluminum grid lines as an example, the width of the bus electrode 330 may be 0.08-0.5 mm, for example, 0.08 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.32 mm, 0.35 mm, 0.38 mm, 0.40 mm, 0.42 mm, 0.45 mm, 0.48 mm or 0.50 mm.

[0055] According to an embodiment of the present application, the width of the first collecting electrode is determined according to actual needs. The width of the first collecting electrode 320 can be 0.015~0.08mm, for example, it can be 0.015mm, 0.020mm, 0.025mm, 0.030mm, 0.035mm, 0.040mm, 0.045mm, 0.050mm, 0.055mm, 0.060mm, 0.065mm, 0.070mm, 0.075mm or 0.080mm.

[0056] According to an embodiment of the present application, the width of the second collector electrode 340 is 0.015-0.083 mm, for example, 0.015 mm, 0.020 mm, 0.025 mm, 0.030 mm, 0.035 mm, 0.040 mm, 0.045 mm, 0.050 mm, 0.055 mm, 0.060 mm, 0.065 mm, 0.070 mm, 0.075 mm, 0.080 mm or 0.083 mm.

[0057] According to the embodiments of the present application, the width of the electrode is related to the preparation on the one hand, and to the material on the other hand. The width of the electrode will affect the conductivity. A certain degree of width increase is beneficial to improving the conductivity. If it is too wide, it will lead to higher material costs and easily cause contact with semiconductor layers of different conductivity types, causing a short circuit.

[0058] According to the embodiments of the present application, Figure 2 As shown, in one embodiment, the back contact battery of the present application can be a full-cell battery, and its substrate has an electrode area, which is suitable for forming an electrode layer thereon to collect the current generated by the entire cell; in other embodiments, the back contact battery of the present application can be a complete cell before cutting and slicing, and its substrate can include at least one separator area and electrode areas located on both sides of each separator area, and the at least two electrode areas are suitable for forming electrode layers thereon respectively to collect the current generated by the sliced ​​cell respectively and independently; in other embodiments, the back contact battery of the present application can also be a sliced ​​cell after the above-mentioned complete cell is cut and sliced, and its substrate can also include a separator area and an electrode area located on one side of the separator area, and the electrode area is suitable for forming an electrode layer thereon to collect the current generated by the sliced ​​cell.

[0059] For example, Figure 4 is a schematic diagram of the arrangement of electrode layers on the surfaces of both sides of the separation region according to another exemplary embodiment of the present application; Figure 4 As shown, taking the complete battery cell before cutting and slicing as an example, it can be understood that before and after cutting and slicing, the substrate can also have a separation area 120 extending along the second direction b and an electrode area 110 located on one side of the separation area 120; wherein, optionally, one end of the second collecting electrode 340 can be connected to the first collecting electrode 320 closest to the separation area, and the first collecting electrode 320 closest to the separation area has the same polarity as the second collecting electrode 340.

[0060] According to an embodiment of the present application, the back-contact solar cell may include at least one separator 120, and the substrate may be separated into a plurality of electrode regions by the separator 120. A laser may be used to cut along the separator 120 to form a plurality of sliced ​​cells, for example, a standard-size cell may be cut into two half-cells by one separator 120, and then welded in series, or a standard-size cell may be cut into three small cells by two separators 120, and then welded in series, and so on.

[0061] Optionally, the spacing between the first collector electrodes on both sides of the separation area 120 may be 0.5-1.5 mm, for example, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, etc. More preferably, the first collector electrode for collecting minority carriers is closer to the separation area than the first collector electrode for collecting majority carriers, so as to shorten the minority carrier collection path, thereby significantly improving the battery carrier collection efficiency.

[0062] According to an embodiment of the present application, the second collecting electrode is connected to the first collecting electrode closest to the separation zone. It is only necessary to add the second collecting electrode. The end of the second collecting electrode close to the separation zone is closer to the separation zone than the end of the first bus electrode close to the separation zone. An end of the first collecting electrode close to the first edge closest to the separation zone extends to the end of the second collecting electrode close to the separation zone to achieve electrical connection.

[0063] According to the embodiments of the present application, Figure 2 As shown, the substrate has two second edges 312 arranged opposite to each other, each extending along the second direction b; the first collector electrode closest to the separation area 120 and / or the second edge can be a continuous structure extending continuously along the second direction b without being broken in the middle. The "second edge" here can be the two side edges of the full cell, the two side edges of the full cell before cutting and slicing, and the two side edges of the slicing cell after cutting and slicing.

[0064] At this time, the first collector electrode 320 closest to the separation area 120 and / or the second edge can also be a discontinuous structure along the second direction b, with a break F, and the break can allow the bus structures of different polarities to pass through. Figure 1 As shown, for example, the fracture may be 0.87 mm. In the embodiment of the present application, the separation area and / or the edge is a continuous structure, which is conducive to the collection of carriers at the edge or separation area. At the same time, continuous insulating material can be directly printed on the continuous structure, which is not easy to cause insulation failure.

[0065] In actual application, the structure of the first collector electrode closest to the separation area 120 and / or the second edge can be set according to actual needs. For example, the first collector electrodes closest to the two second edges can both be continuous structures extending along the second direction b; or they can both be discontinuous structures along the second direction b; or the first collector electrode closest to one of the second edges can be a continuous structure extending along the second direction b, and the first collector electrode closest to the other second edge can be a discontinuous structure along the second direction b. Similarly, the structure of the first collector electrode closest to both sides of the separation area 120 also has the same three situations as the first collector electrode closest to the two second edges. Because the continuous electrode can improve the regulation of carrier transmission and achieve better current transmission; the disconnected collector electrode can provide a certain insulation space to avoid short circuit, so it can be used in combination according to actual needs.

[0066] According to an embodiment of the present application, the above-mentioned back-contact solar cell further includes a semiconductor layer, such as Figure 5A and 5B As shown, the semiconductor layer is located between the substrate 100 and the electrode layer, and includes:

[0067] The first semiconductor region 210 is arranged in an array with different conductivity types alternately spaced along a first direction a and extends along a second direction b. At this time, the first direction a is perpendicular to Figure 5A and Figure 5B The direction of the paper;

[0068] At least two second semiconductor regions 220, each extending along the first direction a, the second semiconductor region 220 is connected to the first semiconductor region 210 of the same conductivity type and isolated from the first semiconductor region 210 of a different conductivity type, wherein the second semiconductor region 220 closest to the first edge 311 is an edge semiconductor region 221;

[0069] A third semiconductor region 230 , located between the edge semiconductor region 221 and the first edge 311 , the third semiconductor region 230 having a conductivity type different from that of the edge semiconductor region 221 ;

[0070] The first collector electrode 320 is located on the first semiconductor region 210 , the bus electrode 330 is located on the second semiconductor region 220 , and the second collector electrode 340 is located on the third semiconductor region 230 .

[0071] According to an embodiment of the present application, the first semiconductor region 210 is disposed on the surface of the substrate 100 or is at least partially embedded in the surface of the substrate 100 with a higher doping concentration than the substrate 100, and the second semiconductor region 220 is disposed on the surface of the substrate 100 or is at least partially embedded in the surface of the substrate 100 with a higher doping concentration than the substrate 100.

[0072] The back-contact solar cell of the present application may be a traditional IBC cell (interdigitated back-contact cell), or a HPBC cell (composite passivated back-contact cell), a TBC cell (TOPCon back-contact cell) or a hybrid back-contact cell (i.e., the PN passivation therein is a different passivation material, for example, a combination of polycrystalline silicon passivation and amorphous / microcrystalline passivation).

[0073] Exemplarily, the above-mentioned IBC battery (interdigitated back contact battery, not shown in the figure) includes a first semiconductor region 210 disposed on a substrate 100 and alternately arranged along a first direction a to form an interdigitated semiconductor structure together with a second semiconductor region 220, such as Figure 3 A. One of the adjacent first semiconductor regions is N-type and the other is P-type. At this time, the first semiconductor region 210 and the second semiconductor region 220 can be respectively heavily doped regions embedded in the surface of the substrate 100 formed by an inner expansion process to form a high-low junction or a PN junction. At this time, the second semiconductor region 220 may include an edge semiconductor region close to the first edge 311, and the above-mentioned IBC battery may also include a third semiconductor region located between the edge semiconductor region and the first edge 311, and a heavily doped region embedded in the surface of the substrate 100 is formed by an inner expansion process.

[0074] Exemplarily, the above-mentioned TBC cell (TOPCon back contact cell) may include a first semiconductor region 210 formed by alternating doped polysilicon layers of different conductivity types along a first direction a. The second semiconductor region 220 has the same film composition as the first semiconductor region 210 of the same conductivity type. The second semiconductor region 220 is connected to at least part of the first semiconductor region 210 of the same conductivity type and isolated from the first semiconductor region 210 of the different conductivity type. Optionally, the first semiconductor region 210 further includes a tunneling oxide layer disposed between the substrate 100 and the doped polysilicon layer, such as Figure 5A As shown. Compared with IBC cells, TBC cells can provide longer carrier lifetime and lower surface recombination, which is beneficial to improving the photoelectric conversion efficiency of TBC cells. Optionally, the second semiconductor region 220 may include an edge semiconductor region 221 close to the first edge, and the TBC cell may further include a third semiconductor region 230 formed by a patterned doped polysilicon layer, located between the edge semiconductor region 221 close to the first edge and the first edge 311.

[0075] Exemplarily, the HPBC battery comprises a first semiconductor region 210 having a first conductivity type formed by a patterned doped polysilicon layer, and a first semiconductor region 210 having a second conductivity type formed in a substrate surface, forming an alternatingly arranged semiconductor structure, and further comprises a second semiconductor region 220 formed in the substrate surface, the second semiconductor region 220 being connected to at least a portion of the first semiconductor region 210 having the same conductivity type and being isolated from the first semiconductor region 210 having a different conductivity type, such as Figure 3 B. Optionally, the HPBC battery includes an edge semiconductor region 221 having a first conductivity type formed by a patterned doped polysilicon layer, and a third semiconductor region 230 having a second conductivity type formed in the substrate surface, and the third semiconductor region 230 is located between the edge semiconductor region 221 and the first edge 311. Optionally, the HPBC battery includes an edge semiconductor region 221 having a second conductivity type formed in the substrate surface, and a third semiconductor region 230 having a first conductivity type formed by a patterned doped polysilicon layer, and the third semiconductor region 230 is located between the edge semiconductor region 221 and the first edge 311. Optionally, the first semiconductor region 210 or the third semiconductor region 230 provided with the doped polysilicon layer further includes a tunneling oxide layer provided between the substrate 100 and the doped polysilicon layer.

[0076] The hybrid back contact cell may have a conductive type region using a layer structure similar to that of an IBC cell or a TBC cell, and another conductive type region may be configured with a passivation layer structure corresponding to a heterojunction on this basis, such as a combination of at least two of polycrystalline silicon passivation, amorphous silicon passivation and microcrystalline silicon passivation. Optionally, the hybrid back contact cell includes a first semiconductor region 210 having a first conductive type formed by a patterned doped polycrystalline silicon layer, and a first semiconductor region 210 having a second conductive type formed by a patterned stacked intrinsic amorphous silicon layer-doped amorphous silicon layer-TCO layer, forming an alternatingly arranged semiconductor structure. Optionally, the first semiconductor region 210 provided with a doped polycrystalline silicon layer also includes a tunneling oxide layer provided between the substrate 100 and the doped polycrystalline silicon layer.

[0077] Based on the above exemplary embodiments, the third semiconductor region 230 is located between the edge semiconductor region 221 and the first edge 311, and has a different conductivity type from the adjacent edge semiconductor region 221. If the edge semiconductor region 221 adjacent to the third semiconductor region 230 is of the first conductivity type, the film layer structure of the edge semiconductor region 221 of the first conductivity type is the same as the first semiconductor region 210 of the same conductivity type, and the specific film layer setting can refer to the prior art or the above description; if the edge semiconductor region 221 adjacent to the third semiconductor region 230 is of the second conductivity type, the film layer structure of the edge semiconductor region 221 of the second conductivity type can be the same as the first semiconductor region 210 of the same conductivity type, and the specific film layer setting can refer to the prior art or the above description. Optionally, both first edges 311 of the battery cell have edge semiconductor regions 221, and the conductivity types of the two edge semiconductor regions 221 corresponding to the two first edges 311 can be the same or different.

[0078] According to an embodiment of the present application, exemplarily, the first semiconductor region 210 includes P-type semiconductor regions and N-type semiconductor regions alternately arranged, and the first collector electrodes are respectively located on the first semiconductor region 210, that is, the first collector electrode with positive polarity is located in the P-type semiconductor region, and the first collector electrode with negative polarity is located in the N-type semiconductor region, and the bus electrode 330 is located on the second semiconductor region 220; at this time, the second semiconductor region 220 closest to the first edge is the edge semiconductor region 221, and if the edge semiconductor region 221 is a P-type semiconductor region, the third semiconductor region 230 is an N-type semiconductor region, and the second collector electrode 340 has a negative polarity; if the edge semiconductor region 221 is an N-type semiconductor region, the third semiconductor region 230 is a P-type semiconductor region, and the second collector electrode 340 has a positive polarity.

[0079] According to an embodiment of the present application, the structural design of the first semiconductor region and the second semiconductor region matches the structural design of the bus electrode and the first collecting electrode, and the second collecting electrode matches the structural design of the third semiconductor region, thereby effectively collecting carriers of corresponding conductive types.

[0080] According to an embodiment of the present application, the conductivity type of the third semiconductor region 230 is preferably different from that of the substrate 100, so that the second collecting electrode 340 is used to collect minority carriers at the edge of the battery. At this time, the first bus electrode 331 is suitable for collecting majority carriers. Compared with setting the second collecting electrode 340 to collect majority carriers, such a setting has a more significant effect on improving the battery carrier collection efficiency.

[0081] Optionally, since the conductivity type of the third semiconductor region 230 is different from that of the substrate 100, in order to avoid edge short circuit, an edge isolation zone can be formed on the side of the third semiconductor region 230 close to the first edge, for example, by removing the portion of the third semiconductor region 230 close to the first edge using a laser to form the edge isolation zone. The third semiconductor region 230 can also be provided to increase the junction area, increase the effective light-emitting area for generating carriers, and improve the efficiency of the cell.

[0082] Of course, it is not limited to this. The conductivity type of the third semiconductor region 230 can also be the same as the substrate 100. Although the effect of improving the battery carrier collection efficiency is slightly worse than the case where its conductivity type is different from the substrate 100, since the third semiconductor region 230 with the same conductivity type as the substrate will not have an edge short circuit when located at the edge, there is no need to form an edge isolation zone at the edge of the battery by, for example, laser removal of the doped area.

[0083] According to the embodiments of the present application, Figure 6 As shown, the edge of the separation zone or the second edge is represented by a dotted line, where the edge of the separation zone is an imaginary edge, for example, it can be the location of the cutting line. The first collector electrode 320 closest to the separation zone and / or the second edge is a continuous structure that extends continuously along the second direction b and is not broken in the middle. At this time, the second semiconductor region 220 having the same conductivity type as the edge semiconductor region 221 is taken as the target semiconductor region 222. Along the first direction a, the distance L3 from the end of the target semiconductor region closest to the separation zone 120 or the second edge 312 to the first collector electrode closest to the separation zone 120 or the second edge 312 is greater than 0.5 mm.

[0084] According to an embodiment of the present application, by precisely controlling the distance between the first collector electrode closest to the separation region or the second edge and the second semiconductor region, the collector electrode with a continuous structure is not easily arranged across the second semiconductor region to cause a short circuit under appropriate printing accuracy.

[0085] According to the embodiments of the present application, Figure 2 As shown, the first bus electrode 331 is a discontinuous structure composed of a plurality of segmented bus electrodes spaced apart in the first direction a; in the first direction a, the spacing between adjacent ends of the segmented bus electrodes is greater than 0.5L and less than or equal to 1L, where L is the distance between adjacent first collector electrodes of the same polarity along the first direction a. At this time, the remaining bus electrodes 330 except the first bus electrode 331 in the bus electrode 330 are second bus electrodes 332, which can be a continuous structure or a discontinuous structure, and the number thereof can be 0 or at least one.

[0086] In this way, the discontinuous structure of the first bus electrode 331 is conducive to balancing the bus effect and preventing leakage.

[0087] According to the embodiments of the present application, Figure 2 and Figure 4 As shown, the electrode layer also includes a plurality of first contact pads 303, which are arranged in an array along the first direction a, and at least one first contact pad 303 is connected to a segmented bus electrode, for example, one first contact pad 303 may be connected to a segmented bus electrode, and / or two first contact pads 303 may be connected to a segmented bus electrode. Setting the number of first contact pads and segmented bus electrodes in this way is conducive to balancing the bus effect and preventing leakage.

[0088] According to an embodiment of the present application, along the first direction a, the spacing between adjacent first contact pads 303 is preferably 8-12 mm, for example, 8 mm, 9 mm, 10 mm, 11 mm or 12 mm.

[0089] According to an embodiment of the present application, in order to take into account both the bus effect and space utilization, the first contact pad 303 and the first bus electrode 331 can be arranged non-collinearly. Specifically, the first contact pad 303 is located on the side of the first bus electrode away from the first edge 311 and is connected to the first bus electrode.

[0090] like Figure 2 As shown, other contact pads except the first contact pad 303 may be second contact pads 304 , and the second contact pad 304 may be arranged in a co-linear manner with the second bus electrode 332 and connected to the second bus electrode 332 .

[0091] According to the embodiments of the present application, Figure 2 As shown, there is a gap between adjacent segmented bus electrodes; the second collector electrode 340 is connected to the first collector electrode passing through the gap. The above structure increases the number of first collector electrodes in contact with the second collector electrode, reduces the transmission distance of edge carriers on the second collector electrode, and is conducive to improving the collection effect of edge carriers.

[0092] According to an embodiment of the present application, when the number of bus electrodes 330 is an odd number, the second collecting electrode 340 includes two grid lines with the same polarity respectively located at the two first edges 311; when the number of bus electrodes 330 is an even number, the second collecting electrode 340 includes two grid lines with different polarities respectively located at the two first edges 311.

[0093] According to an embodiment of the present application, when the number of bus electrodes is an odd number or an even number, the second collecting electrodes have different polarity designs.

[0094] According to an embodiment of the present application, optionally, Figure 2As shown, the substrate at the end of the first edge 311 is provided with a chamfer, and along the first direction a, the distance L4 between the end of the second collector electrode 340 close to the chamfer and the chamfer edge can be 2-3 mm, for example, 2 mm, 2.1 mm, 2.4 mm, 2.5 mm, 2.7 mm, 2.9 mm or 3.0 mm. It can be understood that the distance L4 is the extension distance from the end of the second collector electrode 340 extending along the first direction a to the intersection with the chamfer edge.

[0095] According to the embodiments of the present application, in the case of a chamfer, by controlling the distance between the second collector electrode and the chamfer, it is helpful to avoid the second collector electrode bridging semiconductor layers of different conductivity types, thereby causing a short circuit.

[0096] According to the embodiment of the present application, for knotless screen printing, there is no knot in the opening area in the direction of the first collector electrode 320, but there may be knots in the opening area in the direction of the second collector electrode 340. Based on this, the embodiment of the present application designs the shape of the second collector electrode 340 to improve the printing effect of the knotless screen.

[0097] Further optionally, if Figure 7 As shown, the second collector electrode 340 can be an electrode extending in a fold line along the first direction a, the period T of the fold line is 0.15-0.25 mm, for example, it can be 0.15 mm, 0.17 mm, 0.19 mm, 0.20 mm, 0.22 mm or 0.25 mm, and the angle θ of the fold line is 120°-180°, for example, it can be 120°, 130°, 135°, 140°, 150°, 160°, 170° or 120°. The fold line design of the above size is conducive to improving the effect of using a knotless screen printing.

[0098] It should be noted that when the electrode is manufactured by ordinary screen printing or other electrode manufacturing methods (such as vapor deposition), the above-mentioned mesh knot problem does not exist, and the second collector electrode 340 can be a straight line, a folded line or any other shape. At this time, the side of the second collector electrode 340 close to the first edge 311 is a folded line, and when calculating the distance between it and the first edge 311, for example, it can be the average value of the distance L1 between a plurality of uniformly distributed sampling points on the side and the first edge 311 within a folded line period.

[0099] According to another embodiment of the present application, a photovoltaic assembly is provided, comprising: a plurality of the above-mentioned back-contact solar cells connected in series to form a solar cell string; and a packaging structure disposed around the periphery of the solar cell string.

[0100] According to the embodiments of the present application, the packaging structure may include a backplane, a packaging film, a glass panel, etc., to improve the stability of the solar cell string. The glass panel is located on the front of the solar cell string, and the backplane is located on the back of the solar cell string, both of which play a protective role; the adhesive film is an adhesive film between the solar cell string and the glass panel and the backplane, which plays a role of bonding and fixing, and must be made of a transparent material.

[0101] According to an embodiment of the present application, the substrate of the back-contact solar cell further has two second edges 312 disposed opposite to each other, each extending along the second direction b, and an electrode region located between the second edges 312;

[0102] The first collector electrode 320 closest to the second edge 312 is a continuous structure with a first polarity, and has an insulating material such as insulating glue on the continuous structure to electrically isolate it from other bus structures with different polarities such as welding strips or conductive back plates.

[0103] By providing insulating material between the first collector electrode that is continuously arranged near the separation area and other bus structures, the risk of insulation failure is reduced.

[0104] Taking HPBC as an example, the battery size is 182*183.75mm, including 19 bus electrodes. Figure 1 and Figure 2 The back-contact solar cell is made by cutting it into P half and N half, with 7 contact points on each bus electrode, denoted as BSL; the same battery specifications are used, according to Figure 2 The back-contact solar cell was made by cutting it into P half and N half, which were recorded as SY. The performance of 1418 SY cells and 1632 BSL cells was tested, and the test results were averaged, as shown in Table 1. From the analysis of Table 1, it can be seen that the efficiency of SY is 0.04% higher than that of BSL, which is mainly reflected in the open circuit voltage Uoc gain of 0.3mV, the short circuit current Isc gain of 37mA, and the fill factor FF decline of 0.12. Although the fill factor has decreased slightly, the design of the second collector electrode improves the current collection effect, which shows the improvement of battery performance as a whole.

[0105] Table 1

[0106]

[0107] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A back-contact solar cell, comprising: A base having two first edges disposed opposite to each other and each extending along a first direction; An electrode layer, located on the substrate, comprising: A plurality of first collector electrodes are arranged in an array alternately with different polarities in the first direction, and each of the electrodes extends along a second direction intersecting the first direction; at least two bus electrodes, each extending along the first direction, the bus electrodes being connected to first collector electrodes of the same polarity and electrically isolated from first collector electrodes of different polarities, wherein the bus electrode closest to the first edge is the first bus electrode; and The second collecting electrode extends along the first direction and is located between the first bus electrode and the first edge. The second collecting electrode has a polarity different from that of the first bus electrode and is connected to at least one first collecting electrode with the same polarity.

2. The back-contact solar cell according to claim 1, wherein: The distance between the side of the second collector electrode close to the first edge and the first edge is The ratio of distances between adjacent sides of the second collector electrode and the first bus electrode is 1:4-4:

1.

3. The back-contact solar cell according to claim 1, wherein: The substrate also has a separation region extending along the second direction and an electrode region located on one side of the separation region; One end of the second collecting electrode is connected to the first collecting electrode closest to the separation region, and the first collecting electrode closest to the separation region has the same polarity as the second collecting electrode.

4. The back-contact solar cell according to claim 1, wherein: The base also has two second edges that are oppositely disposed and each extends along the second direction; At least one of the first collecting electrodes closest to the second edge is a continuous structure extending continuously along the second direction.

5. The back-contact solar cell according to claim 4, further comprising a semiconductor layer located between the substrate and the electrode layer, the semiconductor layer comprising: first semiconductor regions, arranged in an array with different conductivity types alternately spaced along the first direction and extending along the second direction; at least two second semiconductor regions, each extending along the first direction, the second semiconductor regions being connected to the first semiconductor regions of the same conductivity type and isolated from the first semiconductor regions of different conductivity types, wherein the second semiconductor region closest to the first edge is an edge semiconductor region; a third semiconductor region, located between the edge semiconductor region and the first edge, the third semiconductor region having a conductivity type different from that of the edge semiconductor region; The first collector electrode is located on the first semiconductor region, the bus electrode is located on the second semiconductor region, the second collector electrode is located on the third semiconductor region, and, The second semiconductor region having the same conductivity type as the edge semiconductor region is taken as the target semiconductor region. Along the first direction, the distance from the end of the target semiconductor region closest to the second edge to the first collector electrode closest to the second edge is greater than 0.5 mm.

6. The back-contact solar cell according to claim 1, wherein: The substrate also has a separation region extending along the second direction and an electrode region located on one side of the separation region; At least one of the first collecting electrodes closest to the separation region is a continuous structure extending continuously along the second direction.

7. The back-contact solar cell according to claim 6, further comprising a semiconductor layer located between the substrate and the electrode layer, the semiconductor layer comprising: first semiconductor regions, arranged in an array with different conductivity types alternately spaced along the first direction and extending along the second direction; at least two second semiconductor regions, each extending along the first direction, the second semiconductor regions being connected to the first semiconductor regions of the same conductivity type and isolated from the first semiconductor regions of different conductivity types, wherein the second semiconductor region closest to the first edge is an edge semiconductor region; a third semiconductor region, located between the edge semiconductor region and the first edge, the third semiconductor region having a conductivity type different from that of the edge semiconductor region; Wherein, the first collector electrode is located on the first semiconductor region, the bus electrode is located on the second semiconductor region, and the second collector electrode is located on the third semiconductor region; and, The second semiconductor region having the same conductivity type as the edge semiconductor region is taken as the target semiconductor region. Along the first direction, the distance from the end of the target semiconductor region closest to the separation region to the first collector electrode closest to the separation region is greater than 0.5 mm.

8. The back-contact solar cell according to claim 1, wherein: The first bus electrode is a discontinuous structure composed of a plurality of segmented bus electrodes distributed at intervals in the first direction; There is a gap between adjacent segmented electrodes; the second collector electrode is connected to the first collector electrode passing through the gap.

9. The back-contact solar cell according to claim 8, wherein: In the first direction, the spacing distance between adjacent ends of the segmented bus electrodes is greater than 0.5L and less than or equal to 1L, where L is the distance between adjacent first collector electrodes of the same polarity along the first direction.

10. The back-contact solar cell according to claim 1, wherein: The substrate at the first edge end is provided with a chamfer, and along the first direction, the distance between the end of the second collector electrode close to the chamfer and the chamfer edge is 2-3 mm.

11. The back-contact solar cell according to any one of claims 1 to 10, wherein: The second current collecting electrode is an electrode extending in a zigzag line along the first direction, the period of the zigzag line is 0.15-0.25 mm, and the angle of the zigzag line is 120°-180°.

12. A photovoltaic module, comprising: A plurality of back-contact solar cells according to any one of claims 1 to 11, connected in series to form a solar cell string; as well as The packaging structure is arranged around the outer periphery of the solar cell string.

13. The photovoltaic module according to claim 12, wherein: The substrate of the back-contact solar cell further comprises two second edges arranged opposite to each other, each extending along the second direction and an electrode region located between the second edges; The first collector electrode closest to the second edge is a continuous structure with a first polarity, and the continuous structure is provided with insulating materials at intervals.

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