Solar photovoltaic module and preparation method thereof
Technical Field
The invention relates to the technical field of solar cell manufacturing, in particular to a solar photovoltaic module and a preparation method of the photovoltaic module.
Background
The solar photovoltaic power generation industry has become a new industry which is concerned and developed intensively all over the world due to the characteristics of cleanness, safety, convenience, high efficiency and the like.
With the continuous progress of solar energy technology and the high-speed growth of large-scale system power stations, as the available photovoltaic power generation land resources are continuously reduced, the demand of high-efficiency crystalline silicon battery components is continuously increased, the solar market is developed in the future, and the photovoltaic power generation is mainly focused on the development and application of the high-efficiency crystalline silicon battery components.
In the current market, the mainstream of a solar cell module adopts a conventional module formed by interconnecting tin-coated copper strips, the core element of a photovoltaic module is a cell, and because a single cell is inconvenient to transport, easy to damage and low in voltage, the cell needs to be packaged and connected in series to reach a certain required voltage, the conventional module is generally formed by connecting 60 or 72 cells in series, and a certain distance of gap is required to be reserved between the cells due to the requirement of electrical performance. The sunlight irradiating the gap position is refracted and reflected for multiple times, and then a part of sunlight is bound to finally irradiate the outside of the assembly, and the battery piece on the current market is provided with the main grid lines and the thin grid lines.
Disclosure of Invention
In view of the above, it is an object of the present invention to provide an improved solar photovoltaic module in order to overcome the drawbacks of the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
a solar photovoltaic module comprises a front plate, a packaging layer, a battery layer and a composite bottom plate which are sequentially arranged from top to bottom, wherein the battery layer comprises at least one battery piece, the front surface of the battery piece is not provided with a main grid line on the traditional battery piece, the front surface of the battery piece is only provided with a thin grid line on the traditional battery piece, the edge of the solar battery piece is provided with a through groove which penetrates through the solar battery piece in the thickness direction and/or the inside of the solar battery piece is provided with a through hole which penetrates through the solar battery piece in the thickness direction, the through groove and the through hole are filled with conductive materials to form a front electrode, the front electrode is electrically connected with the thin grid line, the front electrode penetrates through the back surface of the solar battery piece from the front surface of the solar battery piece, and the back surface of the battery piece is provided with a back electrode; the composite bottom plate comprises a conductive circuit board, a back plate and an adhesive film, wherein the conductive circuit board is matched with the battery piece, and the adhesive film is positioned between the conductive circuit board and the back plate.
The through grooves or the through holes are regularly arranged at the intersection of the thin grid lines, so that on one hand, the guide current can be rapidly collected, on the other hand, the excessive grooves or holes can be avoided, the illumination area of the battery piece is reduced, and the appearance of the battery piece is more concise and attractive. The integrated composite bottom plate can be prepared in advance, and the assembly is quick, time-saving and labor-saving during assembly, and is convenient to replace subsequently.
The front surface of the cell is not provided with the main grid line, so that the shading area is greatly reduced, the absorptivity of light energy is greatly increased, the conversion efficiency of the cell is greatly increased, and the power of the cell is effectively increased; the front surface of the battery piece adopts the dense mesh-shaped fine grid line design, so that the current collection path is shorter, and the series resistance of the battery piece is reduced; the positive and negative electrodes are arranged on the back of the battery piece, so that the complexity of the working procedure is reduced, and the production cost is further reduced.
In some preferred embodiments of the present invention, the conductive circuit board includes an insulating plate and conductive traces disposed on the insulating plate, the conductive traces are disposed adjacent to the battery piece, the insulating plate is disposed adjacent to the adhesive film, and the conductive traces are disposed corresponding to the front electrode and the back electrode on the back surface of the battery piece.
In some preferred embodiments of the present invention, the inner walls of the through-grooves and the through-holes are coated with an insulating material to prevent an electrical contact between the conductive material and the inner walls of the through-grooves or the through-holes.
The conductive material is selected from conductive adhesive, specifically, the conductive adhesive is an organic or inorganic mixture containing 80-90% (mass percent) of silver, is fluid at normal temperature, has viscosity of 80-110Pa.s (25 ℃), and has volume resistivity of less than or equal to 1.82x10-40hm cm, after curingSolid, the curing condition is curing for 5min at 145 ℃, the cured product has certain resilience, and the elasticity value is G'<2x107Pa; the insulating material is a compound adhesive with good electrical insulating property, can bond various metals and plastics, does not need surface pretreatment, has quick curing time, approximate viscosity of 20000CPS (25 ℃), and superimposed shear strength of 4200PSI at normal temperature, has the function of preventing the conductive material from being in electrical contact with the inner wall of the through groove or the through hole, and is coated into the through groove or the through hole in a spraying mode.
In some preferred embodiments of the present invention, the through-hole is circular or rectangular, the through-groove is partially circular or rectangular, and the size of the through-hole and the through-groove is 0.3mm to 1.5 mm. When the diameter of the circle is small enough, the perforation can be considered as a dot.
In some embodiments, the size of the through groove at the corner of the solar cell is one fourth of the size of the through hole, and the size of the through groove at the side edge of the solar cell is one half of the size of the through hole. That is, the through holes in the solar cell are completely circular or rectangular, the through grooves at the four corners of the solar cell are quarter circular or rectangular, and the through grooves at the four sides of the solar cell are half circular or rectangular.
In some preferred embodiments of the present invention, a distance between a vertical line formed by the back electrode of the solar cell sheet and a vertical line formed by the front electrode in a vertical direction is less than or equal to 10 mm.
In a specific implementation application, the design of the back electrode of the battery piece can be a conventional pattern, and is realized by adopting a conventional battery piece screen printing process, but under the condition that the extending direction of the back silver electrode is overlapped with a vertical line formed by the upper through hole and the lower through hole, the crossed position of the back silver electrode needs to be subjected to insulation treatment, or the designed position of the back electrode is wholly shifted, so that the electrical connection between different electrodes is prevented.
In some embodiments, when the back aluminum back field is printed, a spacing distance of 0.5-1mm is left at the positions of the openings and the slots (including the through holes, the through slots, the back silver electrodes and the like), so that on one hand, a step-shaped space can be formed, the welding force between the connection bars is increased, the welding is firmer and more stable, and on the other hand, the distance of 0.5-1mm can prevent the electrodes from being in electrical contact with the aluminum back field.
The invention also provides a preparation method of the solar photovoltaic module, which comprises the following steps: forming a through groove and/or a through hole penetrating through the battery piece in the thickness direction on the battery piece with the thin grid line and the back electrode; coating an insulating material in the through groove and the through hole, filling a conductive material in the through groove and the through hole, and controlling the conductive material to be electrically connected with the fine grid line; combining a plurality of battery sheets to form a battery layer, and coating an insulating material on the side edges of the adjacent battery sheets which are contacted with each other; and placing a packaging layer and a front plate on the front surface of the battery layer, and placing a composite bottom plate on the back surface of the battery layer, so that a front electrode and a back electrode on the back surface of the battery piece are electrically connected with the composite bottom plate, and a solar photovoltaic module is formed after lamination. The lamination parameters are similar to those of the conventional assembly, but the time is increased by 2min in the pressure and heat preservation stage.
In some embodiments of the invention, the front electrode is formed by dripping the conductive material into the through groove or the through hole at normal temperature and then curing the conductive material at 145 ℃ for 5min, and the finally formed front electrode penetrates through the thickness direction of the cell slice, the top of the front electrode is higher than the top of the cell slice, and the bottom of the front electrode is higher than the bottom of the cell slice. The insulating material is sprayed by adopting corresponding prior art means, and the insulating material with the thickness of more than 30 mu m is sprayed on the corresponding part.
In some preferred embodiments of the present invention, the preparation of the composite base plate comprises the following steps: and sequentially placing the conductive circuit board, the adhesive film and the back plate and then laminating to obtain the composite bottom plate. The lamination here is carried out at 140 ℃ for 5-10min in a process chamber with pressure parameters of 20-40 pa.
In some preferred embodiments of the present invention, the through-grooves and the through-holes are prepared by cutting the cell sheet with laser and water alternately to break the cell sheet along a cutting path to form the through-grooves or the through-holes, wherein the cutting is performed initially with laser and it is ensured that the cell sheet does not break after the laser cutting.
The preset cutting path is heated by laser firstly, then the cutting path is cooled by water, and the battery piece is cut off along the cutting path through cold and hot alternation, so that a through groove or a through hole is formed, the section of the prepared through groove or through hole is neat and has no crack, the damage of the battery piece is less, and the hidden crack risk of the battery piece is reduced.
Preferably, the number of the alternate cutting is 1, 2, 3 or more, and the cell sheet is completely broken along the cutting path under the water cutting effect of the last alternate cutting to form the through groove or the through hole. The most preferable alternate cutting times are once, the energy consumption is low, the efficiency is high, and the regularity of the cross section of the through groove or the through hole is more facilitated.
Preferably, in each alternate cutting, the path of laser cutting and the path of water cutting are kept consistent so as to ensure the tidiness of the section at the through groove or the through hole; in each alternate cut, water cutting is performed within 1-2s after laser cutting. In each alternate cutting, water cutting is carried out within 1-2s after laser cutting, the interval time is not longer, poor cutting effect and irregular section caused by excessive cooling of the cell pieces are prevented, and the short interval time is also beneficial to improving the productivity.
Specifically, the laser cutting parameters are as follows: the laser power is 15-20W, the laser frequency is 500-600kHz, and the laser running speed is 18000-22000 cm/min; the laser cutting time is 1-2 s. The parameters of the water cutting are as follows: cutting with deionized water at normal temperature at initial jetting speed of 15000-; the water cutting time is 1-2 s.
In a specific embodiment, a preset cutting path is heated by laser, then the cutting path is cooled by water or other cooling liquid or gas, and the battery piece is cut off along the cutting path through cold and hot alternation, so that a through groove or a through hole is formed, the section of the prepared through groove or through hole is neat and has no crack, the damage of the battery piece is less, and the subfissure risk of the battery piece is reduced. And the cutting method can be used for cutting at any position of the cell slice, such as at the edge or inside of the cell slice and can be used for dividing one cell slice into two or more sliced cell slices.
Compared with the prior art, the invention has the advantages that: according to the solar photovoltaic module, the front electrode of the cell is led to the back of the cell, the front side is basically not shielded by a welding strip, and the cells are not spaced from series connection to parallel connection, so that the area of the module can be reduced under the condition of ensuring the same light absorption area, and the power of the module is improved; the design of the integrated composite bottom plate is adopted, and the battery pieces can be pressed in one step after being connected in series and parallel, so that the production time is greatly reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic front side graphic design diagram of a solar cell sheet according to a preferred embodiment 1 of the present invention;
fig. 2 is a schematic diagram of a backside pattern design of a solar cell in a preferred embodiment 1 of the present invention;
fig. 3 is a schematic diagram of conductive traces of a solar cell in the preferred embodiment 1 of the present invention;
fig. 4 is a schematic front view of a solar photovoltaic module according to a preferred embodiment 1 of the present invention;
fig. 5 is a schematic front side graphic design diagram of a solar cell sheet according to a preferred embodiment 2 of the present invention;
fig. 6 is a schematic diagram of the back side pattern design of a solar cell in preferred embodiment 2 of the present invention;
fig. 7 is a schematic front view of a solar photovoltaic module according to a preferred embodiment 2 of the present invention;
fig. 8 is a schematic view of a composite bottom plate of a solar photovoltaic module in a preferred embodiment 2 of the present invention;
fig. 9 is a sectional SEM image of a solar cell cut by the prior art at a through groove or a through hole;
fig. 10 is a sectional SEM image of a solar cell cut by the prior art at a through groove or a through hole;
fig. 11 is a sectional SEM image of a solar cell cut by the prior art at the through groove or through hole;
fig. 12 is a cross-sectional SEM image of the solar cell prepared in preferred embodiment 1 of the present invention at the through groove or through hole;
fig. 13 is a sectional SEM image of the solar cell prepared in preferred embodiment 1 of the present invention at the through groove or through hole;
fig. 14 is a schematic cross-sectional view of a solar cell prepared in preferred embodiment 1 of the present invention at a through groove or a through hole;
in the attached drawing, a battery piece-1, a through groove-2, a through hole-3, a fine grid line-4, a front electrode-5, a back electrode-6, a photovoltaic module-7, a composite bottom plate-8, a conductive circuit board-81, an adhesive film-82, a back plate-83 and an insulating material-9.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not a whole embodiment. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
As shown in fig. 4, the photovoltaic module 7 of the present embodiment includes a front plate, a front encapsulation layer, a battery layer and a composite bottom plate 8, which are sequentially disposed from top to bottom, wherein the battery layer is formed by arranging a plurality of battery pieces 1.
As shown in fig. 1-2, the back surface of the solar cell 1 of this embodiment has a back electrode 6, but the front surface of the solar cell has no main grid lines, the front surface of the solar cell has thin grid lines 4, and the thin grid lines 4 are in a dense mesh design, and the distance between adjacent thin grid lines 4 is 1-2 mm. The edge of the solar cell piece 1 is provided with a through groove 2 penetrating through the solar cell piece in the thickness direction, and/or the inside of the solar cell piece 1 is provided with a through hole 3 penetrating through the solar cell piece in the thickness direction, and the inside of the through groove 2 and the through hole 3 is coated with an insulating material 9.
The through grooves 2 or the through holes 3 are regularly arranged at the intersection of the plurality of thin grid lines 4, the through grooves 2 and the through holes 3 are filled with a conductive material, and the conductive material is guided to the back surface of the solar cell to form the front electrode 5, that is, the front electrode 5 penetrates from the front surface of the solar cell sheet 1 to the back surface of the solar cell sheet 1, as shown in fig. 14.
The conductive material in the embodiment is selected from conductive adhesive, specifically, the conductive adhesive is an organic or inorganic mixture containing 80-90% of silver, is fluid at normal temperature, has viscosity of 80-110Pa.s (25 ℃), and has volume resistivity of less than or equal to 1.82x10-40hm & cm, is solid after being cured, is cured for 5min at the temperature of 145 ℃, has certain rebound resilience after being cured, and has the elasticity value of G'<2x107Pa; the insulating material 9 is an insulating adhesive which is a composite adhesive with good electrical insulating property, can bond various metals and plastics, does not need surface pretreatment, is quick in curing time, has a viscosity of approximately 20000CPS (25 ℃), and has an overlap shear strength of 4200PSI at normal temperature, and has the function of preventing the conductive material from being in electrical contact with the inner wall of the through groove 2 or the through hole 3, and the insulating material 9 is coated into the through groove 2 or the through hole 3 in a spraying mode.
The through hole 3 is circular or rectangular, the through groove 2 is partially circular or rectangular, and the size of the through hole 3 and the size of the through groove 2 are 0.3-1.5 mm. When the diameter of the circle is small enough, the through-hole 3 can be regarded as a dot. The size of the through groove 2 at the corner of the solar cell piece 1 is one fourth of the size of the through hole 3, and the size of the through groove 2 at the side edge of the solar cell piece 1 is one half of the size of the through hole 3. That is, the through holes 3 in the solar cell are completely circular or rectangular, the through grooves 2 at the four corners of the solar cell sheet 1 are quarter circular or rectangular, and the through grooves 2 at the four sides of the solar cell sheet 1 are half circular or rectangular.
The through hole 3 in this embodiment is a circle with a diameter of 0.8mm, the through grooves 2 at the four corners are quarter circles, and the through grooves 2 at the sides are half circles. As shown in fig. 1, the battery sheet 1 may be divided into a plurality of rectangles, and each of the corners of the rectangles has a through-hole 3 or a through-groove 2.
As shown in fig. 8, the composite chassis 8 includes a conductive wiring board 81 fitted to the battery sheet 1, a back plate 83, and an adhesive film 82 between the conductive wiring board 81 and the back plate 83. The conductive circuit board 81 includes an insulating board and a conductive circuit disposed on the insulating board, the conductive circuit is close to the battery piece 1, the insulating board is close to the adhesive film 82, the conductive circuit is disposed corresponding to the front electrode 5 and the back electrode 6 on the back of the battery piece 1, and the conductive circuit is electrically connected to the front electrode 5 or the back electrode 6.
The distance between a vertical line formed by the back electrode 6 of the solar cell piece 1 and a vertical line formed by the front electrode 5 in the vertical direction is less than or equal to 10 mm. The design of the back electrode 6 of the battery piece 1 can be a conventional pattern, and is realized by adopting a screen printing process of the conventional battery piece 1, but the extending direction of the back silver electrode is overlapped with a vertical line formed by the upper and lower through holes 3, at the moment, the crossed position of the conductive circuits on the conductive circuit board 81 needs to be subjected to insulation treatment, or the designed position of the back electrode 6 is wholly deviated, so that the electrodes are prevented from being electrically connected. The insulation treatment may be applied with the insulation material 9 as described above.
As shown in fig. 3, a circle in the figure represents a front electrode 5 (which is a negative electrode on the electrical property of the battery piece 1) led from the front of the battery piece 1, and a rectangle in the figure represents a back electrode 6 (which is a positive electrode on the electrical property of the battery piece 1) of the battery piece 1, for example, when a circuit is vertically routed, the front electrode 5 and the back electrode 6 are on the same vertical line, when the battery pieces 1 are connected in series, the positive electrode and the negative electrode need to be distinguished, and a single circuit connected with the front electrode 5 and a conductive circuit connected with the back electrode 6 need to be avoided or crossed. As shown in fig. 3, an insulation process is required when crossing each other. For example, when the circuit for connecting the front electrode 5 and the circuit for connecting the back electrode 6 are routed in the horizontal direction, the front electrode 5 and the back electrode 6 are not on the same horizontal line, and thus the connection can be performed directly without avoiding or crossing.
When the back aluminum back field is printed, a spacing distance of 0.5-1mm is reserved at the positions of the holes and the grooves (including the through holes 3, the through grooves 2, the back electrodes 6 and the like), on one hand, a step-shaped space can be formed, the welding force between the connecting strips is increased, the welding is firmer and more stable, and on the other hand, the distance of 0.5-1mm can prevent the electrodes from being in electrical contact with the aluminum back field.
By such an arrangement, the space between adjacent battery plates 1 is reduced or even no space is provided, and more battery plates 1 can be accommodated in the photovoltaic module 7 with the same size, as shown in fig. 4. The photovoltaic module 7 in this embodiment is smaller in length and width than the conventional module by 10 to 30mm, and is lighter in weight by 3 to 6kg than the conventional module.
Example 2
The embodiment provides a method for preparing the solar photovoltaic module 7 described in embodiment 1, which specifically includes the following steps:
1) a cell 1 with prepared thin grid lines 4 and back electrodes 6 is selected, and through grooves 2 and/or through holes 3 penetrating through the cell in the thickness direction are formed in the cell.
The method for manufacturing the through groove 2 or the through hole 3 provided in this embodiment is to cut the battery piece 1 alternately with laser and water to break the battery piece 1 along the cutting path to form the through groove 2 or the through hole 3, wherein the cutting is performed with laser at the beginning and it is ensured that the battery piece 1 is not broken after the laser cutting.
The parameters of laser cutting in this example are as follows: the laser power is 20W, the laser frequency is 600kHz, the laser running speed, namely the moving speed of a laser is 22000cm/min, and the laser cutting time of the single cell piece 1 is 1 s. The parameters for water cutting were as follows: the temperature is normal temperature, the adopted water is deionized water, the initial speed of spraying during cutting is 20000cm/min, and the time of water cutting of the single cell piece 1 is 1 s. Here the initial velocity of the spray is the velocity of the water as it leaves the cutting head of the cutting machine.
In the embodiment, the number of times of alternate cutting is one, the energy consumption of one-time alternate cutting is low, the efficiency is high, and the trimming of the sections at the through grooves 2 or the through holes 3 is facilitated. In other embodiments, the number of the alternate cutting is 2, 3 or more, and the cell sheet 1 completely breaks the through groove 2 formed along the cutting path by the water cutting of the last alternate cutting.
As shown in fig. 8 to 12, the cross section of the cell 1 prepared in example 1 and the cross section of the cell 1 cut by laser in the prior art, such as through groove 2 or through hole 3, are scanned by scanning electron microscope. As can be seen from the attached drawings, the cross section of the through groove 2 or the through hole 3 formed by adopting a laser cutting preparation method is irregular, the damage is large, and cracks exist; the section of the through groove 2 or the through hole 3 formed by the method in embodiment 1 of the invention is neat and has no crack, the damage to the battery piece 1 is less, and the hidden crack risk of the battery piece 1 is reduced.
In each alternate cut, the path of the laser cut and the path of the water cut are kept identical to ensure the regularity of the section at the point of penetration of the tank 2. In each alternate cutting, water cutting is carried out within 2s after laser cutting, the interval time is not too long, poor cutting effect caused by excessive cooling of the cell 1 is prevented, and the short interval time is also beneficial to improving the productivity.
Specifically, after the printing of the cell piece 1 is finished, the cell piece 1 is adsorbed and fixed, the laser is started, the infrared nanosecond laser beam is used for scribing and heating the preset part of the cell piece 1, the diameter of a laser spot is 110 micrometers, the laser heating time of the single cell piece 1 is 1-2s, and the laser is turned off after the printing is finished. And then, the water jet cutter is opened, the preset part of the battery piece 1 is repeatedly scribed and cooled, the cooling time of the single battery piece 1 is 1-2s, and the scribing path of the laser is consistent with that of the water jet cutter, so that the grooved part at the edge of the battery piece 1 is rapidly broken through cold and hot alternation, and the damage to the neat section is small. And blowing the battery piece 1 subjected to slotting to complete the whole slotting process.
2) The insulating material 9 is firstly sprayed in the through groove 2 and the through hole 3, the insulating material is required to be uniformly sprayed on the section of the slotting part of the battery piece 1, the spraying thickness reaches more than 30 mu m, then the conductive material is filled, the conductive material is controlled to be electrically connected with the thin grid line 4, and the conductive material is prevented from being electrically contacted with the inner wall of the through groove 2 or the through hole 3.
The front electrode 5 is formed by dropping a conductive material into the through groove 2 or the through hole 3 at normal temperature, and then curing the conductive material at 145 ℃ for 5min, so that the finally formed front electrode 5 penetrates through the thickness direction of the battery piece 1, the top of the front electrode 5 is higher than the top of the battery piece 1, and the bottom of the front electrode 5 is higher than the bottom of the battery piece 1 to be electrically connected with a conductive circuit, as shown in fig. 14.
A plurality of prepared battery pieces 1 are combined to form a battery layer, and insulating materials 9 are coated on the side edges where the adjacent battery pieces 1 are contacted. The insulating material 9 used in example 1 can be used as well.
3) The packaging layer and the front plate are placed on the front side of the battery layer, and the composite bottom plate 8 is placed on the back side of the battery layer, so that the front electrode 5 and the back electrode 6 on the battery piece 1 are electrically connected with the conductive circuit on the composite bottom plate 8 and are laminated to form the solar photovoltaic module 7. The lamination parameters of the novel component are similar to those of the conventional component, and the time of the pressure and heat preservation stage is increased by 2 min.
The preparation of the composite bottom plate 8 comprises the following steps: the conductive wiring board 81, the adhesive film 82, and the back plate 83 are sequentially placed and then laminated to obtain the composite bottom plate 8. The adhesive film 82 can be the adhesive film 82 of the conventional photovoltaic module 7. The composite bottom plate 8 is formed by coating glue among the conductive circuit board 81, the glue film 82 and the back plate 83, heating and pressing are carried out after coating, pressing is carried out only in a process chamber at 140 ℃ for 5-10min, and the pressure parameter is 20-40 pa.
The shading area of the front side of the photovoltaic module 7 prepared by the manufacturing method is greatly reduced, the absorption rate of light energy is greatly increased, and the photoelectric conversion efficiency in unit area is effectively increased.
Example 3
As shown in fig. 5 to 7, the photovoltaic module 7 and the solar cell sheet 1 in the present embodiment are substantially similar to those in embodiment 1, except that: in the embodiment, the solar cell pieces 1 are not provided with the through grooves 2 at the four corners and two sides, so that the cell pieces 1 can only be longitudinally connected with each other to form a cell string and cannot be transversely connected when the photovoltaic module 7 is prepared.
The method for forming the through-grooves 2 and the through-holes 3 in this example is substantially similar to that in example 1, except that: in this embodiment, the number of the main grid lines of the battery piece 1 is 12, and the parameters of the laser cutting in this embodiment are as follows: the laser power is 15W, the laser frequency is 500kHz, the laser running speed, namely the moving speed of a laser is 18000cm/min, and the laser cutting time of the single cell piece 1 is 2 s. The parameters for water cutting were as follows: the temperature is normal temperature, the adopted water is deionized water, the initial spraying speed during cutting is 15000cm/min, and the water cutting time of the single cell piece 1 is 2 s; and water cutting is performed within 1s after the laser cutting. Here the initial velocity of the spray is the velocity of the water as it leaves the cutting head of the cutting machine.
The starting materials not specifically mentioned in the above examples were all obtained commercially. The operation without particular reference to temperature is carried out at room temperature. The methods and conditions not specifically described may be those well known or conventional in the art.
Example 4
The photovoltaic module of example 1 was compared with a conventional photovoltaic module as described in the background, with the following results:
TABLE 1 comparison of results
As can be seen from table 1, when the photovoltaic module of embodiment 1 is designed to be seamless connected, the photoelectric conversion efficiency in unit area is further greatly increased, the conversion efficiency in unit area is significantly improved, the assembly installation cost can be effectively reduced, and the power-assisted internet access is realized at a low price. And the composite bottom plate is adopted, and the battery pieces can be pressed in one step after being connected in series and parallel, so that the production time is greatly reduced, the integrated back plate design does not generate delamination risk, the reliability is higher, and the production cost is effectively reduced.
The above embodiments are merely illustrative of the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the content of the present invention and implement the invention, and not to limit the scope of the invention, and all equivalent changes or modifications made according to the spirit of the present invention should be covered by the scope of the present invention.