This application is based upon and claims foreign priority benefits under 35 U.S.C. § 119(a)-(d) or 35 U.S.C. § 365(b) to Chinese Patent Application No. 201711268793.5, filed Dec. 5, 2017, titled “Solar cell sheet and preparation method thereof, solar cell string and photovoltaic module”, and Chinese Patent Application No. 201721672980.5, filed Dec. 5, 2017, titled “Double-sided power generation solar cell sheet, cell string and double-sided power generation photovoltaic module”, the entire contents of which are incorporated herein by reference.
The present disclosure relates to the technical field of solar energy, and in particular, relates to a solar cell sheet and a preparation method thereof, a solar cell string and a photovoltaic module.
With the development of solar cell technology, heterojunction solar cell has become one of the mainstream solar cells with its high efficiency and high stability. According to different installation methods and installation environments, the actual outdoor power generation of the heterojunction solar cells is 15%-30% higher than the actual outdoor power generation of conventional crystalline silicon cell. An important indicator for evaluating the performance of the heterojunction solar cells is the short-circuit current density Jsc. The larger the short-circuit current density Jsc is, the higher the efficiency of the heterojunction solar cell is.
The first aspect of the present disclosure provides a solar cell sheet, the solar cell sheet includes: a conductive connection member; and a first electrode, a first transparent conductive layer, a first doped layer of a first conductivity type, a first passivation layer, a monocrystalline silicon wafer, a second passivation layer, a second doped layer of a second conductivity type, a second transparent conductive layer, and a second electrode arranged in an order from top to bottom, one end of the conductive connection member is electrically connected to the first electrode, the other end of the conductive connection member extends to a side of the second transparent conductive layer adjacent to the second electrode, and the conductive connection member is insulated from the second transparent conductive layer and the second electrode.
The second aspect of the present disclosure further provides a method for preparing a solar cell sheet, and the method for preparing the solar cell sheet includes:
providing a first through hole in a monocrystalline silicon wafer, the monocrystalline silicon wafer comprising first and second surfaces which are opposite;
performing a texturing operation and a cleaning operation on both of the first and the second surfaces;
forming a first passivation layer and a first doped layer on the first surface sequentially, and forming a second passivation layer and a second doped layer on the second surface sequentially;
forming a first transparent conductive layer on a surface of the first doped layer away from the first passivation layer, and forming a second transparent layer on the surface of the second doped layer away from the second passivation layer; and
preparing a first electrode on a surface of the first transparent conductive layer away from the first doped layer, preparing a second electrode on a surface of the second transparent conductive layer away from the second doped layer, and preparing a conductive connection member located in the first through hole when preparing the first electrode or preparing the second electrode, such that one end of the conductive connection member is connected to the first electrode, and the other end of the conductive connection member extends to a side of the second transparent conductive layer adjacent to the second electrode.
A third aspect of the present disclosure further provides a solar cell string, including: a plurality of the solar cell sheets, the plurality of solar cell sheets are electrically connected together.
The fourth aspect of the present disclosure further provides a photovoltaic module, including a front plate, a first bonding layer, a solar cell string, a second bonding layer, and a backing plate in an order from top to bottom; wherein the solar cell string is the above solar cell string.
The embodiments of the present disclosure are described in detail below, and the examples of the embodiments are illustrated in the drawings, wherein the same or similar reference numerals are used to refer to the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are intended to be illustrative and explain the present disclosure only, and are not to be construed as limiting.
In the related art, the heterojunction solar cell has the characteristic of double-sided power generation. Therefore, both electrodes on two opposite surfaces of the heterojunction solar cell include a plurality of fine gate lines and a main gate line which are spaced apart. Since the main gate line blocks a part of a light receiving area of the heterojunction solar cell, the short-circuit current density of the heterojunction solar cell is reduced; accordingly, the photoelectric conversion efficiency of the heterojunction solar cell is reduced. The main gate line is made of silver material. Therefore, when the main gate line is made of a large amount of silver material, the cost of preparing the main gate line is very high.
In addition, the existing solar cell sheet cooperates with a special back plate integrated with positive and negative electrodes by a Metal Wrap Through (MWT) back contact technology to achieve an interconnection between two adjacent solar cells. However, since the special back plate integrated with the positive and negative electrodes is non-transparent, when the back plate of the solar cell is the special back plate integrated with positive and negative electrodes, the solar cell cannot realize the double-sided power generation function. Moreover, since the special back plate integrated with positive and negative electrodes is generally expensive, it is not conducive to the control of industrialization costs.
As shown in
In conjunction with
It may be understood that, as shown in
In addition, the solar cell sheet 100 provided by the embodiments of the present disclosure does not need to use a special back plane integrated with positive and negative electrodes. Therefore, the solar cell sheet 100 provided by the embodiments of the present disclosure can realize double-sided solar power generation.
In some embodiments, the conductive connection member 102 described above may be made of metal.
In some embodiments, as shown in
In some embodiments, as shown in
A width of each of the plurality of first gate lines b1 is generally set to be from 30 μm to 90 μm. For example, the width of each of the plurality of first gate lines b1 is 30 μm, 90 μm, 45 μm, or 70 μm. A width direction of each of the plurality of first gate lines b1 is perpendicular to a linear direction of a corresponding first gate line of the plurality of first gate lines b1.
In some embodiments, as shown in
In some embodiments, as shown in
In some embodiments, as shown in
In some embodiments, as shown in
When the conductive connection member 102 is disposed in the through hole 101, an orthographic projection of the conductive connection member 102 on one surface of the monocrystalline silicon wafer 50 at least overlaps with an orthographic projection of the first confluence point 11 on one surface of the monocrystalline silicon wafer 50. At this time, the first confluence point 11 is located at an end of the sixth through hole a6 of the first transparent conductive layer 20 away from the first doped layer 30. At the same time, an orthographic projection of the conductive connection member 102 on one surface of the monocrystalline silicon wafer 50 and an orthographic projection of the second confluence point 91 on one surface of the monocrystalline silicon wafer 50 are independent from each other to avoid the conductive connection member 102 is electrically connected to the second confluence point 91.
In some embodiments, as shown in
As shown in
In some embodiments, as shown in
In some embodiments, as shown in
In the first implementation manner, the first doped layer 30 is an N-type amorphous silicon-based doped layer, and the second doped layer 70 is a P-type amorphous silicon-based doped layer.
In the second implementation manner, as shown in
In some embodiments, as shown in
In some embodiments, when the first transparent conductive layer 20 and the second transparent conductive layer 80 are both conductive layers, and when the first transparent conductive layer 20 is provided with a sixth through hole a6, and the second transparent conductive layer 80 is provided with a sixth through hole a7, a part of the conductive connection member 102 is located in the sixth through hole a6 and the seventh through hole a7. At this time, the conductive connection member 102 may influence the photoelectric conversion efficiency of the solar cell sheet 100. With respect to this problem, an inner wall of the through hole 101 is provided with an insulating film c. The material of the insulating film c is an ethylene-vinyl acetate copolymer (EVA), polyvinyl butyral (PVB) or Dai Nippon Printing (DNP) material.
In some embodiments, referring to
In one implementation, as shown in
In another implementation manner, as shown in
In addition, when a plurality of second gate lines b2 included in the second electrode 90 join together at a second confluence point 91, the second confluence point 91 should be spatially offset from the insulating hole 801 and the through hole 101 to ensure that the conductive connection member 102 disposed in the through hole 101 and the second confluence point 91 are in an insulated state. In other words, the orthographic projection of the second confluence point 91 on the plane of the one of the surfaces is outside the region enclosed by the annular orthographic projection. At this time, although the conductive connection member 102 is inserted in the region surrounded by the transparent conductive layer 80 corresponding to the annular orthographic projection, the conductive connection member 102 will not be electrically connected with the second confluence point 91 formed by joining the plurality of second gate lines b2 included in the second electrode 90. Therefore, although the above-mentioned conductive connection member 102 electrically connected to the first electrode is inserted in the region surrounded by the annular orthographic projection corresponding to the transparent conductive layer 80, the first electrode 10 connected with the conductive connection member 102 will not be electrically connected to the second electrode 90 contacting the second transparent conductive layer 80.
In some embodiments, referring to
In addition, as shown in
As shown in
In some embodiments, as shown in
In other embodiments, when preparing the conductive connection member 102, it is not necessary to use silver material, and only a general metal material such as a copper or a tin-plated copper is used, therefore, the manufacturing cost of the above-mentioned conductive connection member 102 is relatively low.
As shown in
In S1, a first through hole a1 is formed in the monocrystalline silicon wafer 50, and the monocrystalline silicon wafer 50 includes a first surface 501 and a second surface 502 which are opposite with each other. There are many ways for forming the first through hole a1 in the monocrystalline silicon wafer 50. For example, the first through hole a1 is formed in the monocrystalline silicon wafer 50 by laser drilling.
In S2, the first surface 501 and the second surface 502 are both subjected to a texturing operation and a cleaning operation. The texturing operation means forming a suede having a pyramidal pattern on both the first surface 501 and the second surface 502, and a size (a maximum span) of the pyramid is 1 μm to 10 μm. The texturing operation may reduce the reflectance of the surface of the monocrystalline silicon wafer 50, so as to increase the photoelectric conversion efficiency of the prepared solar cell sheet 100.
In S3, the first passivation layer 40 and the first doped layer 30 are sequentially formed on the first surface 501 described above. A second passivation layer 60 and a second doped layer 70 are sequentially formed on the second surface 502 described above.
In some embodiments, the sequentially forming the first passivation layer 40 and the first doped layer 30 on the first surface 501 includes: sequentially depositing a first passivation layer 40 and a first doping layer 30 on the first surface 501, so that the first passivation layer 40 includes a second through hole a2, and the first doped layer 30 includes a third through hole a3. And the orthographic projections of the first through hole a1, the second through hole a2, and the third through hole a3 on the plane where the first surface 501 is located are overlapped.
The forming sequentially the second passivation layer 60 and the second doped layer 70 on the second surface 502 includes: sequentially depositing a second passivation layer 60 and a second doped layer 70 on the second surface 502, so that the second passivation layer 60 includes a fourth through hole a4, and the second doped layer 70 includes a fifth through hole a5. And the orthographic projections of the first through hole a1, the fourth through hole a4, and the fifth through hole a5 on the plane of the second surface 502 are overlapped.
In some embodiments, the deposition method may be a Plasma Enhanced Chemical Vapor Deposition (PECVD) or a Hot Wire Chemical Vapor Deposition (HWCVD). The two passivation layers of the first passivation layer 40 and the second passivation layer 60, and the two doped layers of the first doped layer 30 and the second doped layer 70 are deposited in the same manner. The first passivation layer 40 and the second passivation layer 60 are deposited in the same step but in different chambers.
Illustratively, the first passivation layer 40 and the second passivation layer 60 are simultaneously formed in the same chamber, and then the first doped layer 30 and the second doped layer 70 are formed in another chamber.
In some embodiments, the first doped layer 30 is an N-type amorphous silicon-based doped layer. The second doped layer 70 is a P-type amorphous silicon-based doped layer.
In some other embodiments, the first doped layer 30 is a P-type amorphous silicon-based doped layer. The second doped layer 70 is an N-type amorphous silicon-based doped layer.
In some embodiments, the first passivation layer 40 and the second passivation layer 60 are both amorphous silicon basic passivation layers.
In S4, a first transparent conductive layer 20 is formed on the surface of the first doped layer 30 away from the first passivation layer 40. A second transparent conductive layer 80 is formed on the surface of the second doped layer 70 away from the second passivation layer 60.
In some embodiments, forming the first transparent conductive layer 20 on the surface of the first doped layer 30 away from the first passivation layer 40 includes: depositing the first transparent conductive layer 20 on the surface of the first doped layer 30 away from the first passivation layer 40, so that the first transparent conductive layer 20 includes a sixth through hole a6. The orthographic projections of the first through hole a1 and the sixth through hole a6 on the plane of the first surface 501 are overlapped.
The forming the second transparent conductive layer 80 on the surface of the second doped layer 70 away from the second passivation layer 60 includes: depositing the second transparent conductive layer 80 on the surface of the second doped layer 70 away from the second passivation layer 60, so that the second transparent conductive layer 80 includes a seventh through a7. The orthographic projections of the first through hole a1 and the seventh through hole a7 on the plane of the second surface 502 are overlapped.
The above deposition method may be a Physical Vapor Deposition (PVD), or may be a remote plasma coating method. The remote plasma coating method is also called as Plasma Reactive Deposition (PRD).
The first through hole a1, the second through hole a2, the third through hole a3, the fourth through hole a4, the fifth through hole a5, the sixth through hole a6, and the seventh through hole a7 are communicated to form the through hole 101.
In some embodiments, the first transparent conductive layer 20 and the second transparent conductive layer 80 are both TCO glass conductive layers.
In S5, the first electrode 10 is prepared on the surface of the first transparent conductive layer 20 away from the first doped layer 30. The second electrode 90 is prepared on the surface of the second transparent conductive layer 80 away from the second doped layer 70. Moreover, the conductive connection member 102 located in the first through hole a1 is prepared when preparing the first electrode 10 or preparing the second electrode 90.
In some embodiments, the step of preparing the first electrode 10 on the surface of the first transparent conductive layer 20 away from the first doped layer 30 and the step of preparing the second electrode 90 on the surface of the second transparent conductive layer 80 away from the second doped layer 70 are performed successively.
The preparing the conductive connection member 102 in the first through hole a1 when preparing the first electrode 10 or preparing the second electrode 90 includes:
preparing the conductive connection member 102 located in the through hole 101 when preparing the first electrode 10 or when preparing the second electrode 90.
In some embodiments, when the number of the through holes is multiple, the foregoing S1 includes:
forming a plurality of first through holes a1 on the monocrystalline silicon wafer 50 by laser drilling; and/or
as shown in
in S501, a plurality of first gate lines b1 are printed on the surface of the first transparent conductive layer 20 away from the first doped layer 30 by a screen printing process to form a first electrode 10 composed of a plurality of first gate lines b1, the plurality of first gate lines b1 join to form a plurality of first confluence points 11, and the orthographic projections of the plurality of first confluence points 11 on the plane of the first surface 501 are located in the orthographic projections of the through holes 101 on the plane of the first surface 501 in a one-to-one correspondence; and/or
as shown in
in S502, a plurality of second gate lines b2 are printed on the second transparent conductive layer 80 by a screen printing process to form a second electrode 90 composed of a plurality of second gate lines b2, the plurality of second gate lines b2 join to form a plurality of second confluence points 91, and the orthographic projections of the plurality of second confluence points 91 on the plane of the second surface 502 are outside the annular orthographic projection of the insulating hole 801 on the plane of the second surface 502 in a one-to-one correspondence; and/or
the preparing the conductive connection member in the first through hole a1 when preparing the first electrode 10 or when preparing the second electrode 90 includes: step 503 (S503) and step 504 (S504).
In S503, when printing the plurality of first gate lines b1 or printing the plurality of second gate lines b2, filling the plurality of through holes a5 with silver paste.
In S504, drying the silver paste filled in the plurality of through holes 101, so that the silver paste filled in the plurality of the through holes 101 is solidified, thereby a plurality of conductive connection members 102 are obtained, and the plurality of conductive connection members 102 are located in the plurality of the through holes 101 in a one-to-one correspondence.
Since the orthographic projections of the plurality of first confluence points 11 on the plane of the first surface 501 are located within the orthographic projection of the first through hole a1 on the plane of the first surface 501, and the orthographic projections of the plurality of second confluence points 91 on the plane of the second surface 502 and the orthographic projection of the first through hole a1 on the plane of the second surface 502 are independent from each other, when the plurality of conductive connection members 102 are located in the plurality of the through holes 101 in a one-to-one correspondence, one ends of the plurality of conductive connection members 102 may be electrically connected to the first confluence point 11 in a one-to-one correspondence, the other ends of the plurality of conductive connection members 102 are not electrically connected to the plurality of second confluence points 91.
It may be seen that: after the plurality of conductive connection members 102 are formed in the plurality of through holes 100 in a one-to-one correspondence, the current extraction end of the first electrode 10 is led out through the plurality of conductive connection members 102 to the surface of the second transparent conductive layer 80 adjacent to the second electrode 90, so that the current extraction end of the first electrode 10 is located on the same side as the second electrode 90.
In some embodiments, the first electrode 10 and the second electrode 90 are made of the silver paste and a resin material.
Illustratively, the silver paste and the resin material are mixed to form a premix with a mass percent greater than 90%. The premix is printed on the surface of the second transparent conductive layer 80 away from the second doped layer 70 by the screen printing process, so that a plurality of second gate lines b2 are formed on the surface of the second transparent conductive layer 80 away from the second doped layer 70. Similarly, a premix is printed on the surface of the first transparent conductive layer 20 away from the first doped layer 30 by the screen printing process, so that a plurality of second gate lines b2 are formed on the surface of the first transparent conductive layer 20 away from the first doped layer 30.
In some embodiments, as shown in
In one embodiment, as shown in
In S401, the material of the first transparent conductive layer 20 and the material of the second transparent conductive layer 80 formed in the inner wall of the through hole 101 (for example, the forming manner is deposition manner) are removed by a corrosion process or a laser etching process. When the material of the first transparent conductive layer 20 and the material of the second transparent conductive layer 80 formed in the inner wall of the through hole 101 are removed by the corrosion process, it is possible to use a strong alkali to corrode the material of the first transparent conductive layer 20 and the material of the second transparent conductive layer 80 formed in the inner wall of the through hole 101. The strong alkali includes an inorganic alkali such as sodium hydroxide or potassium hydroxide.
Since a total thickness of the first passivation layer 40, the first doped layer 30, the first transparent conductive layer 20, the second passivation layer 60, the second doped layer 70, and the second transparent conductive layer 80 is nanometer scale, for convenience of operation, the material of the first transparent conductive layer 20 and the material of the second transparent conductive layer 80 formed on the inner wall of the through hole 101 consisting of the first through hole a1, the second through hole a2, the third through hole a3, the fourth through hole a4, the fifth through hole a5, the sixth through hole a6, and the seventh through hole a7 may be corroded for one time, in this way, the method of removing the material of the first transparent conductive layer 20 and the material of the second transparent conductive layer 80 is simple and convenient to operate, and has a high reliability.
Illustratively, the first doped layer has a thickness of 6 nm, the second doped layer has a thickness of 8 nm, and the first transparent conductive layer 20 and the second transparent conductive layer 80 both have a thickness of 80 nm.
In some embodiments, as shown in
In S402, an insulating film c is prepared on the inner wall of the through hole 101 and the surface of the second transparent conductive layer 80 for contacting the conductive connection member 102. The insulating film c is an ethylene-vinyl acetate copolymer (EVA) material layer, a polyvinyl butyral material layer or a Dai Nippon Printing (DNP) plastic layer. Since the material of the first transparent conductive layer 20 and the material of the second transparent conductive layer 80 are conductive materials, in order to prevent the material of the first transparent conductive layer 20 and the material of the second transparent conductive layer 80 on the inner wall of the through hole 101 from affecting the current collection by the electrode, in particular, it is necessary to provide an insulating film on the inner wall of the sixth through hole a6 included in the through hole 101 and the inner wall of the seventh through hole a7 included in the through hole 101. Since the first passivation layer 40, the first doped layer 30, the first transparent conductive layer 20, the second passivation layer 60, the second doped layer 70, and the second transparent conductive layer 80 have a total thickness of nanometer scale, the insulating film c is entirely provided on the inner wall of the through hole 101, and it is not necessary to define the position where the insulating film c is formed, so that it is convenient to form the insulating film c on the inner wall of the through hole 101. Further, providing the insulating film c entirely on the inner wall of the through hole 101 can also ensure a good insulation between the conductive connection member 102 and the first transparent conductive layer 20, the second transparent conductive layer 80.
Referring to
In some other embodiments, as shown in
In S403, an annular insulating hole 801 is formed in the second transparent conductive layer 80, so that the orthographic projection of the insulating hole 801 on the plane of the second surface 502 is an annular orthographic projection. The orthographic projection of the seventh through hole a7 included in the through hole 101 on the plane of the second surface 502 is located in the region surrounded by the annular orthographic projection. The orthographic projection of the seventh through hole a7 included in the through hole 101 on the plane of the second surface 502 and the orthographic projection of the conductive connection member 102 on the plane of the second surface 502 are both located in the region enclosed by the annular orthographic projection, and the orthographic projection of the second confluence point 91 on the plane of the second surface 502 is outside the region enclosed by the annular orthographic projection. At this time, the region surrounded by the second transparent conductive layer 80 corresponding to the annular orthographic projection is not only insulated from the outer region of the second transparent conductive layer 80 corresponding to the annular orthographic projection, but also insulated from the second electrode 81. Since the region surrounded by the second transparent conductive layer 80 corresponding to the annular orthographic projection is electrically connected to the conductive connection member 102, by providing the insulating hole 801 on the second transparent conductive layer 102, the insulating holes 801 may insulate the conductive connection members 102 from the second transparent conductive layer 80 and the second electrode 90.
The manner in which the second transparent conductive layer 80 and the conductive connection member 102 are insulated by the insulating holes 801 is simpler and easier to operate. The first transparent conductive layer 20 is in contact with the first electrode 10, and the conductive connection member 102 is electrically connected to the first electrode, therefor the polarity of the first transparent conductive layer 20 is the same as that of the conductive connection member 102, and the conductive connection members 102 can be insulated from the second transparent conductive layer 80 and the second electrodes by only providing the insulating holes 801 in the second transparent conductive layer 80.
As shown in
Compared with the related art, the beneficial effects of the solar cell string 200 provided by the embodiments of the present disclosure are the same as those of the solar cell sheet 100 provided by the above embodiments, which are not described herein.
It should be understood by those skilled in the art that, as shown in
In some embodiments, as shown in
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In some embodiments, as shown in
Illustratively, as shown in
Illustratively, the conductive connection member 102 has a thickness of 0.01 mm to 0.2 mm and a width of 0.6 mm to 12 mm. Compared with the conventional silver main gate line, the above-mentioned conductive connecting line 102 is also smaller in size, which reduces the shielding of the light receiving surface of the solar cell sheet 100, thereby improving the conversion efficiency of the solar cell sheet 100.
It may be understood that, as shown in
The shapes of the first confluence point 11 and the second confluence point 91 in
In some embodiments, the above conductive connecting line 210 is made of a copper strip. The copper strip may be a pure copper strip or a tinned copper strip, but the present disclosure is not limited thereto.
Illustratively, the outer surface of the above conductive connecting line 210 is coated with a layer of insulating material. For example, the insulating material is preferably a rubber or plastic.
When the conductive connection member 200 included in one of the adjacent two solar cell sheets 100 of the plurality of cell sub-strings is electrically connected to the second electrode 90 included in the other solar cell sheet, it is only necessary to expose the inner tinned copper strip by spot welding or gluing the insulating material at the end of the conductive connecting line 210 to ensure the electrical conductivity.
In some embodiments, the temperature of the spot welding described above does not exceed 200 degrees. The temperature of the above low temperature curing does not exceed 220 degrees.
In addition, as shown in
As shown in
Compared with the related art, the beneficial effects of the photovoltaic module 300 provided by some embodiments of the present disclosure are the same as those of the solar cell sheet 100 described above, and are not elaborated herein.
In some embodiments, the first bonding layer 320 and the second bonding layer 330 are both ethylene-vinyl acetate copolymer (EVA) material layer and polyvinyl butyral (PVB) material layer, a polyolefin elastomer (POE) material layer or a thermoplastic silicone layer.
The structures, features and effects of the present disclosure have been described in detail above with reference to the embodiments shown in the drawings. The above is only the preferred embodiment of the present disclosure, but the disclosure does not limit the scope of the implementation as shown in the drawings. All changes which come within the spirit and scope of the present disclosure are intended to be included within the protection scope of the present disclosure.
Number | Date | Country | Kind |
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201711268793.5 | Dec 2017 | CN | national |
201721672980.5 | Dec 2017 | CN | national |