Detailed Description
The present application will be described in detail below with reference to embodiments shown in the drawings. The present invention is not limited to the above embodiments, and structural, methodological, or functional changes made by one of ordinary skill in the art according to the present embodiments are included in the scope of the present invention. The terms "first" and "second" do not represent any sequence relationships, but are merely used for distinguishing between the descriptions, and specific meanings of the terms can be clearly understood by those skilled in the art.
A photovoltaic Module (PV Module) generally includes a plurality of photovoltaic cells arranged in an array, and the photovoltaic cells can be connected into a plurality of cell strings, and the cell strings are connected in series and/or parallel to form the Module. In each cell string, two adjacent photovoltaic cells may be electrically connected by a conductive material (e.g., copper tape or conductive adhesive). Generally, a photovoltaic cell includes a doped semiconductor substrate (e.g., crystalline silicon) and electrodes formed on front and back surfaces of the semiconductor substrate, respectively, and the electrodes may be formed on the semiconductor substrate by printing or sintering. Generally, the electrodes include a plurality of fine grid electrodes for collecting current and a plurality of main grid electrodes cross-connected to the fine grid electrodes for collecting current, and the extending direction of the main grid electrodes coincides with the arrangement direction of each photovoltaic cell in the cell string. For convenience of description, hereinafter, the "electrodes" are all referred to as main gate electrodes.
In order to increase the generated power per unit area of the photovoltaic module, consideration is given to how to increase the light utilization efficiency of the surface of the module and how to reduce or eliminate the gap between adjacent photovoltaic cells. In terms of improvement of light utilization rate, on one hand, since the conductive member is used as a connecting medium for adjacent photovoltaic cells, it needs to cover the surface of the photovoltaic cell, and the covered area cannot be received by light, so that the generated power of the photovoltaic cell is reduced. On the other hand, in addition to the light rays perpendicularly irradiated to the surface of the photovoltaic cell, the light rays reflected to the surface of the photovoltaic cell by other objects can also bring a certain gain of the cell power. Therefore, how to reduce the light shielding on the surface of the battery and how to utilize the reflected light are the current issues to be considered in the industry. With respect to the elimination of the gap between the photovoltaic cells, there are solutions in the industry that facilitate a shingle assembly that overlaps the edges of adjacent photovoltaic cells and uses conductive glue to make electrical connections at the overlapped locations. However, the conductive adhesive itself has a high cost, and the conductive performance and the connection reliability of the conductive adhesive have hidden troubles. To the problem that exists in the industry, this application provides a novel electrically conductive piece for electrically connecting photovoltaic cell.
Fig. 1A and fig. 1B are schematic structural diagrams of a novel conductive device according to an embodiment of the present application. As shown in fig. 1A and 1B, the conductive member 10 includes a non-reflective section 11 and a reflective section 12 integrally formed in a longitudinal direction thereof. The non-light-reflecting section 11 is used to electrically connect with the back side (i.e., the backlight side) of the photovoltaic cell, and the light-reflecting section 12 is used to electrically connect with the front side (i.e., the light-receiving side) of the photovoltaic cell.
The definitions for "retroreflective segments" and "non-retroreflective segments" are as follows:
the reflecting section comprises a plane contact surface and a reflecting surface opposite to the plane contact surface, the reflecting surface can reflect light rays to the surface of the photovoltaic cell, and the reflecting surface comprises a curved surface or an inclined plane not parallel to the contact surface.
The non-light reflecting section comprises a plane contact surface and a non-contact surface opposite to the plane contact surface, and the non-contact surface is plane and approximately parallel to the contact surface.
In the embodiment of the present application, the non-light reflecting section 11 has a first cross section perpendicular to the self length direction, and the light reflecting section 12 has a second cross section perpendicular to the self length direction, and the area of the first cross section needs to be approximately equal to the area of the second cross section. Since the cross-sectional shapes of the non-reflective section 11 and the reflective section 12 are different, if the cross-sectional areas of the non-reflective section and the reflective section are different, the manufacturing process of the conductive device is complicated, and the mass production is not facilitated. For this reason, in the process of manufacturing the conductive device, it is necessary to always maintain the cross-sectional areas of the non-reflective section 11 and the reflective section 12 to be uniform, so as to ensure the productivity of the conductive device. In addition, when the cross-sectional areas of the non-reflective section 11 and the reflective section 12 are different, the resistances of the non-reflective section 11 and the reflective section 12 are different (on the premise that the lengths of the non-reflective section and the reflective section are equal), and the power losses of the non-reflective section 11 and the reflective section 12 are different due to the different resistances, so that the adjacent two photovoltaic cells are mismatched.
Further, the conductive member 10 may further include a transition section 13 connected between the non-reflective section 11 and the reflective section 12, wherein the height of the transition section 13 is smaller than the height of the reflective section 12 and larger than the height of the non-reflective section 11, and the height of the transition section 13 is gradually decreased in a direction away from the non-reflective section 11. The cross-sectional area of the transition section 13 perpendicular to the length direction of the conductive member needs to be approximately equal to the cross-sectional area of the non-reflective section 11 or the reflective section 12 perpendicular to the length direction of the conductive member. Intuitively, the transition section 13 has a certain slope, and its existence can ensure the smooth transition between the non-reflective section 11 and the reflective section 12, so as not to form a shape similar to a step at the junction of the two. On one hand, the transition section 13 can improve the bending performance of the joint position of the two and is not easy to break; on the other hand, the transition section 13 can also avoid scratching the surface of the photovoltaic cell or the edge of the photovoltaic cell in contact with the transition section.
As shown in fig. 2A, in the embodiment of the present application, the non-reflective section 11 may be substantially flat, and its cross section perpendicular to its length direction is substantially rectangular; the cross section of the light reflecting section 12 perpendicular to the length direction thereof is hexagonal, and the light reflecting section 12 has two reflecting surfaces 122, 124 respectively extending along the length direction of the conductive member. Of course, as a possible embodiment, the cross-sectional shape of the light reflecting section 12 perpendicular to the length direction thereof includes, but is not limited to: triangular, trapezoidal, circular, oval, polygonal, etc. In the embodiment, the width of the contact surface of the light-reflecting section 12 in the direction perpendicular to the length direction of the conductive device is defined as W1, and the width of the contact surface of the non-light-reflecting section 11 in the direction perpendicular to the length direction of the conductive device is defined as W2, which satisfies W1 ≦ W2. Since W1 is not more than W2, on one hand, the shading area of the light reflecting section 12 to the front surface (light receiving surface) of the battery can be effectively reduced; on the other hand, the contact area of the non-light reflecting section 11 with the back surface of the battery can be increased, thereby ensuring the reliability of the welding between the back surface of the battery and the non-light reflecting section 11. In addition, because the light is mainly from the front side of the cell, the broadening of the non-reflective segments 11 has negligible effect on the power generation of the cell. Of course, in other embodiments, W1 > W2 is also possible. In this embodiment, the above-mentioned cross-section of the reflector segment 12 is roughly divided into an upper triangular portion and a lower rectangular portion, wherein the height of the rectangular portion is defined as H1, and the height of the reflector segment 12 (i.e. the distance from the contact surface to the apex of the triangular portion) is defined as H0, which should be satisfied for the convenience of production: h0 > H2, and H1 ═ H2. When H1 and H2 are equal, cold rolling by means of two press rolls (described in detail below) is facilitated, and the production efficiency is high.
For a bifacial cell (i.e., a cell that generates electricity on both the front and back sides), the efficiency of light utilization on the back side of the cell is also important. Therefore, the embodiment of the application also provides a conductive piece comprising two reflecting sections.
As shown in fig. 2B, in an embodiment, the conductive member includes a first reflective section 14 and a second reflective section 16 integrally formed in a length direction thereof, the first reflective section 14 has a contact surface and first reflective surfaces 142 and 144 facing away from the contact surface, and the second reflective section 16 has a contact surface and second reflective surfaces 162 and 164 facing away from the contact surface. The first reflective surfaces 142, 144 and the second reflective surfaces 162, 164 are respectively located on different sides of the conductive member in the height direction. In other words, the conductive member is defined to include an upper side and a lower side in a height direction thereof, and the first reflective surfaces 142 and 144 may be located at the upper side and the second reflective surfaces 162 and 164 may be located at the lower side. Similarly, the cross-sectional area of the first light reflecting segment 14 perpendicular to its length direction needs to be approximately equal to the cross-sectional area of the second light reflecting segment 16 perpendicular to its length direction. In the present embodiment, the above-described cross-sections of the first reflector segment 14 and the second reflector segment 16 are equally divided into rectangular portions and triangular portions in the height direction. Defining the height of the rectangular portion of the first light reflecting section 14 as H3, the height of the rectangular portion of the second light reflecting section 16 as H4, the height of the first light reflecting section 14 as H5, the height of the second light reflecting section 16 as H6, the width of the contact surface of the first light reflecting section 14 in the direction perpendicular to the length direction of the conductive member as W3, and the width of the contact surface of the second light reflecting section 16 in the direction perpendicular to the length direction of the conductive member as W4, the following conditions should be satisfied: w3 is not more than W4, H3 is H4, and H5 is not less than H6. Because the utilization rate of the front light has larger influence on the power gain of the double-sided battery, when W3 is less than or equal to W4, the shielding area of the conductive piece on the front side of the battery can be reduced, and meanwhile, the contact area of the conductive piece and the back side of the battery is considered. H3 ═ H4 can make the manufacture of the conductive device easier. Of course, in other embodiments, W3 > W4 is also possible.
Fig. 2C shows another conductive device comprising two reflective segments. The difference from the above fig. 2B is that: the cross section of the second light reflecting section 16 perpendicular to the length direction thereof is circular or elliptical, and the second light reflecting section also has a certain light reflecting effect. The diameter of the second reflector segment 16 is defined as R1.
In the embodiment of the present application, the above parameters need to satisfy the following conditions:
0.2mm≤R1≤0.45mm;
0.2mm≤W3≤0.6mm;
0.2mm≤H5≤0.6mm。
in one embodiment, the conductive member further comprises a transition section (not shown) connected between the first light reflecting section 14 and the second light reflecting section 16, and the transition section is flat (i.e. the cross section perpendicular to the length direction of the conductive member is rectangular).
Fig. 3A-3C illustrate schematic cross-sectional views of additional light-reflecting segments. As shown in fig. 3A, the light-reflecting section includes a planar top 123 extending along the length direction of the conductive member, and the planar top 123 is substantially parallel to the contact surface of the light-reflecting section. As shown in fig. 3B, the light-reflecting section includes a circular arc top 125 extending along the length direction of the conductive member. The plane top 123 and the arc top 125 can reduce the pressure of the reflective section to the packaging adhesive film in the assembly laminating process, and the existence of the plane top 123 and the arc top 125 can also control the height of the reflective section, thereby being beneficial to the assembly laminating process.
Fig. 4 shows a connection state of two adjacent photovoltaic cells in an embodiment of the present application. As shown in fig. 4, the photovoltaic module includes a first photovoltaic cell 21, a second photovoltaic cell 22, and a conductive member electrically connecting the first photovoltaic cell 21 and the second photovoltaic cell 22. The conductive member may include a non-reflective section 11 electrically connected to the back side of the first photovoltaic cell 21 and a reflective section 12 electrically connected to the front side of the second photovoltaic cell 22. In order to increase the generated power per unit area of the module, the edges of two adjacent photovoltaic cells are overlapped to form an overlapping region, and the conductive member passes through the overlapping region. The width W0 of the overlapped area along the length direction of the conductive piece is less than or equal to 1.0mm, and more preferably, 0.3mm is less than or equal to W3 is less than or equal to 1.0 mm. Because adjacent battery pieces are electrically connected through the lengthways extending conductive piece, compared with a laminated assembly which is connected by conductive adhesive, the laminated assembly has higher yield and more advantageous cost, and the width of the overlapping region along the length direction of the conductive piece can be further reduced.
As shown in fig. 5, the difference from fig. 4 is that: and additionally arranging a buffer material layer 30 between the conductive device and the photovoltaic cell in the overlapped region, wherein the buffer material layer 30 is used for relieving the hard contact between the conductive device and the photovoltaic cell, thereby improving the problem of cell cracking caused by the hard contact. The cushioning material layer 30 may be made of a material having certain elasticity or flexibility, such as: EVA (ethylene-vinyl acetate copolymer).
As shown in fig. 6, the difference from fig. 4 is that: a certain pitch (e.g., less than 0.5mm) may exist between two adjacent cells, through which the conductive member passes from the front surface of one cell to the back surface of the other cell.
It should be noted that fig. 4 to 6 above only exemplify the number of the conductive members welded on the surface of the battery, however, the number is not limited in the present application, and may be adjusted to 9, 12, etc. as needed.
As shown in fig. 7A, in the embodiment of the application, a part of the non-reflective section 11 is clamped in the overlapping region, and since the contact area between the non-reflective section 11 and the battery is larger, the hard contact pressure between the conductive member and the battery piece in the overlapping region can be reduced, and the probability that the battery piece is fractured at the overlapping position is further reduced. Furthermore, the light reflecting section 12 may be disposed outside the overlapping region, so as to prevent the sharp-top light reflecting section 12 from scratching the surface of the battery in the overlapping region and prevent the light reflecting section 12 from fracturing the battery.
In the embodiment of the present application, the length L1 of the light reflecting section 12 is smaller than the length L2 of the non-light reflecting section 11, so that the length of one of the non-light reflecting sections 11 electrically connected to the back surface of the first photovoltaic cell 21 is equal to L1, and the length of the other section sandwiched in the overlapping region is: L2-L1. Further, when the lengths of the front electrode and the back electrode of the photovoltaic cell are consistent, the difference between the lengths of the non-reflective section 11 and the reflective section 12 is: L2-L1, defining the width of the overlap region along the length direction of the conductive device as W0, it should satisfy: (L2-L1) ≧ W0, so that the completely flat non-reflective segment 11 is clamped in the overlapping region.
As shown in fig. 7B, the difference from fig. 7A is that: a space may be left between the end of the light reflecting section 12 and the overlap region to further reduce the possibility of scratching the cell or cell splinting.
As shown in fig. 8, the difference from fig. 7 is that: the electrically conductive member comprises a transition section connected between the light-reflecting section 12 and the non-light-reflecting section 11, both the transition section and the light-reflecting section 12 being located outside the overlap region.
Next, the above method for manufacturing the conductive device and the related device will be described with reference to fig. 9A to 12B.
Fig. 9A and 9B are schematic structural views of a device 100 for producing a conductive member according to a first embodiment of the present application, where the device 100 is used for producing a continuous reflective conductive member. The apparatus 100 comprises: a first press roll (e.g., a tungsten steel press roll) 101 and a second press roll 102, wherein each of the first press roll 101 and the second press roll 102 has a cylindrical shape and a gap 103 is provided therebetween. Wherein first press roll 101 has a first rolled surface 110 and second press roll 102 has a second rolled surface 120. One or more parallel grooves 112 of corresponding shape are previously formed in the first rolled surface 110 by mechanical grinding or laser engraving, and the extending direction of the grooves 112 is perpendicular to the rotating shaft of the first press roll 101. The groove 112 extends for a length equal to the circumference of a cross section of the first pressure roller 101 perpendicular to its axis of rotation. Taking the light reflecting section shown in fig. 2A as an example, the cross section of the groove 112 perpendicular to the self-extending direction is substantially triangular, and the width of the groove 112 tends to become gradually larger from inside to outside.
Accordingly, the operation of the above-described apparatus 100 is substantially as follows:
s101: the conductive material 10a to be processed (e.g., a circular conductive tape or a rectangular conductive tape, etc.) is arranged along the extending direction of the grooves 112, and the conductive material 10a is placed in the gap 103 between the first pressing roll 101 and the second pressing roll 102.
S102: first press roller 101 and second press roller 102 are driven to rotate relatively, and the rotation directions of the two rollers are opposite. In this process, the conductive raw material 10a is kept being fed between the first pressing roller 101 and the second pressing roller 102, and the continuous type light reflecting conductive member 10b is manufactured.
Wherein the continuous type light reflecting conductive member 10b is divided into a lower rectangular portion and an upper triangular portion in the height direction thereof, and the height of the rectangular portion is substantially equal to the pitch of the gap 103.
Fig. 10A and 10B are schematic structural views of a device 200 for producing a conductive device according to a second embodiment of the present application, where the device 200 is also used for producing a continuous reflective conductive device. The device 200 is processed in a metal wire drawing manner. The device 200 comprises a drawing channel extending lengthwise, the drawing channel comprises a feeding port 202 and a discharging port 201, wherein, from the feeding port 202 to the discharging port 201, the cross-sectional area of the drawing channel perpendicular to the lengthwise direction of the drawing channel tends to become smaller, and when the discharging port 201 is triangular, the cross section of the produced conductive piece is approximately triangular.
Fig. 11A and 11B are schematic structural diagrams of a device 300 for producing a conductive device according to a third embodiment of the present application, where the device 300 is used to produce a discontinuous reflective conductive device (i.e. including a reflective segment and a non-reflective segment). The non-retroreflective segments and the retroreflective segments may appear periodically, a combined segment composed of a retroreflective segment having a length of L1 and a non-retroreflective segment having a length of L2 is defined as one period, and the length of the combined segment is defined as L3 — L1+ L2. The apparatus 300 comprises a first pressing roller 301 and a second pressing roller 302, and likewise, the first pressing roller 301 and the second pressing roller 302 are both cylindrical. Wherein the first press roll 301 has a first rolled surface 310 and the second press roll 302 has a second rolled surface 320. In this embodiment, the following conditions need to be satisfied: the circumference of the cross section of the first press roller 301 perpendicular to the rotation axis thereof is equal to the above-mentioned length L3, or equal to an integral multiple of the above-mentioned length L3. One or more grooves 312 are formed in the first rolled surface 310 by grinding or laser processing of the first rolled surface 310, and the extending direction of the grooves 312 is perpendicular to the rotating shaft of the first pressing roller 301. The groove 312 has an extension L4 ═ L1. In one example, if the circumference of the cross section of the first platen 301 perpendicular to its rotation axis is equal to the length L3 described above, and L1 is L2, then it is necessary to satisfy: L4-L1-L2-L3/2. The first rolled surface 310 is flat except for the grooves 312.
Accordingly, the operation of the apparatus 300 is substantially as follows:
s301: a conductive material to be processed (e.g., a circular conductive tape or a rectangular conductive tape) is placed between the first rolled surface 310 and the second rolled surface 320, and the conductive material is aligned with the grooves 312.
S302: the first pressing roller 301 and the second pressing roller 302 are driven to perform relative movement, and the rotation directions of the two rollers are opposite. In this process, the conductive material is constantly fed between the first pressing roller 301 and the second pressing roller 302.
Fig. 12A and 12B are schematic structural diagrams of a device 400 for producing conductive elements according to a fourth embodiment of the present application, where the device 400 is used to produce reflective conductive elements that occur periodically (i.e. contain reflective segments and non-reflective segments), and also to produce non-periodic reflective conductive elements. Specifically, the apparatus 400 includes a nip platform 403, a first nip roller 401 and a second nip roller 402 located above the nip platform 403. The distance between the first press roll 401 and the nip platform 403 is equal to the distance between the second press roll 402 and the nip platform 403. Wherein the first press roll 401 has a first rolled surface cooperating with the rolling platform 403, and the second press roll 402 has a second rolled surface cooperating with the rolling platform 403. One or more rows of first grooves 412 extending along the self-rotation direction are formed on the first rolling surface, one or more rows of second grooves 422 extending along the self-rotation direction are formed on the second rolling surface, the first grooves 412 are used for rolling the light reflecting sections, and the second grooves 422 are used for rolling the non-light reflecting sections. The first trenches 412 and the second trenches 422 are arranged at equal intervals, and the interval between two adjacent first trenches 412 is equal to the interval between two adjacent second trenches 422. Further, the first grooves 412 and the second grooves 422 are aligned in position in the rotational direction of the platen roller. In this example, the cross section of the first trench 412 perpendicular to the self length direction may be triangular or trapezoidal, and the cross section of the second trench 422 perpendicular to the self length direction is substantially rectangular. The first grooves 412 have a length substantially equal to the length of the light-reflecting segments and the second grooves 422 have a length substantially equal to the length of the non-light-reflecting segments. In the embodiment of the present application, the length of the retroreflective segments is defined as L1, the length of the non-retroreflective segments is defined as L2, and the distance between the first pressing roller 401 and the second pressing roller 402 is defined as L5, so that the following requirements are satisfied: L5-L1-L2.
Accordingly, the process of the above apparatus 400 is substantially as follows:
s401: the first press roll 401 and the second press roll 402 are moved away from the press platform 403.
S402: conductive material to be rolled (e.g., circular conductive tape) is placed on the rolling platform 403 and is arranged at equal intervals along the first and second grooves 412 and 422.
S403: the first press roll 401 and the second press roll 402 are driven to move toward the nip platform 403 until the first press roll 401 and the second press roll 402 contact the nip platform 403.
S404: the first pressing roller 401 and the second pressing roller 402 are driven to roll in the direction D1 in the drawing. Wherein the first press roller 401 and the second press roller 402 roll a distance substantially equal to the length of the retroreflective segments or the length of the non-retroreflective segments.
In another embodiment, when the conductive device is a flat conductive device, only a portion of the raw material segments need to be rolled periodically to deform the rolled flat conductive segments into triangular conductive segments. Accordingly, in this embodiment, one of the first press roller 401 and the second press roller 402 may be omitted, and the corresponding grooves may be provided on a single press roller.
In the specific embodiment of the present application, it is also necessary to roll a "ramp" transition section between the light reflecting section and the conducting section. Specifically, a rolling tool can be adopted to perform inclined rolling on the transition section between the light reflecting section and the conducting section, so that a slope-shaped transition section is rolled.
In the embodiment of the present application, the conductive member may include a conductive substrate (e.g., a copper substrate) and a solder assistant layer (e.g., a tin layer) covering at least a contact surface of the conductive substrate. In the process of rolling the special-shaped conductive piece, a rolling process can be carried out by taking a conductive substrate as a raw material, and after the required sectional special-shaped conductive piece is obtained by rolling and molding, a corresponding welding-assisting layer is formed on the contact surface of the special-shaped conductive piece. Of course, in an alternative embodiment, a conductive device with a solder mask layer may be produced first, and then the conductive device may be subjected to a rolling process, which is not limited herein.
Fig. 13 is a manufacturing process of a photovoltaic module according to an embodiment of the present application, the method includes steps S1 to S5, where:
step S1: providing a first photovoltaic cell 21;
step S2: providing a second photovoltaic cell 22;
step S3: providing a conductive member with a preset length. The conductive piece comprises a non-reflective section 11 and a reflective section 12, and the cross-sectional area of the non-reflective section 11 perpendicular to the length direction of the conductive piece is equal to the cross-sectional area of the reflective section 12 perpendicular to the length direction of the conductive piece.
Step S4: the non-reflective segment 11 is electrically connected to the back side of the first photovoltaic cell 21.
Step S5: electrically connecting the light-reflecting section 12 to the front side of the second photovoltaic cell 22.
The above steps S1 to S5 do not necessarily have to be defined in order.
In one embodiment, step S3 may include steps S31-S32:
s31: a non-reflective conductive member of a predetermined length is provided, the non-reflective conductive member being divided into a first section and a second section connected to each other.
S32: and applying deformation pressure to the first section in the non-light-reflecting conductive member to deform the first section into a light-reflecting section.
As shown in fig. 13, in another embodiment, step S3 may include S33-S34:
s33: providing a reflective conductive member with a preset length, wherein the reflective conductive member is divided into a first section and a second section which are connected. For example, a triangular conductive member of a certain length is pulled out from a reel 50 for housing the conductive member and cut.
S34: and applying deformation pressure to the first section of the light-reflecting conductive member to deform the first section into a non-light-reflecting section. For example, a pressure plate 60 is used to apply pressure to one of the triangular conductive members to deform the one into the non-reflective segment 11.
In an embodiment, the method further comprises: the first and second photovoltaic cells 21 and 22 are overlapped at their edges to form an overlapped region, and the conductive member is passed through the overlapped region.
In an embodiment, the method further comprises: and clamping part of the non-light reflecting sections 11 in the overlapping area.
In one embodiment, the step S5 includes: the light-reflective segments 12 of the electrically conductive member are electrically connected to the front side of the second photovoltaic cell 22 outside said overlap region.
Next, referring to fig. 14 to 16, the reflection paths of the parallel light irradiated perpendicularly to the surface of the cell by the light reflection sections are shown. The description is given only by way of example of parallel beams perpendicular to the surface of the photovoltaic cell, and the light rays that can be utilized are not limited to the parallel beams. Parallel light beams perpendicular to the surface of the photovoltaic cell penetrate through the light-permeable front plate 40 and then irradiate on the reflecting surface of the light reflecting section 12 welded on the surface of the photovoltaic cell 20.
In the embodiment of the application, the height range of the non-reflective section is 0.1-0.32 mm or 0.2-0.6 mm, and the width range of the contact surface of the reflective section is 0.2-0.9 mm or 0.2-0.6 mm, so that the thickness of an encapsulation adhesive film (such as ethylene-vinyl acetate copolymer EVA) is effectively reduced, the lamination yield of the assembly is ensured, and the cost is saved. In addition, the width range of the contact surface of the non-reflective section is 0.2-1.4 mm or 0.2-1.6 mm, and the height range of the non-reflective section is 0.05-0.3 mm, so that the non-reflective section and the back surface of the battery piece are ensured to have larger contact area, the welding tension is increased, and the reliability of the product is improved.
In the embodiment of the application, the length of the part, in the non-light-reflecting section, in contact with the light receiving surface of the battery along the length direction of the conductive piece is 0.6-1.4 mm, and the distance between two adjacent battery strings is 2.0-3.0 mm. Because parallel incident light rays pass through the front plate and the transparent packaging adhesive film and then irradiate the battery piece and the light-reflecting conductive piece, the light rays irradiating the battery piece can be directly absorbed and utilized to be converted into electric energy, some light rays irradiating the light-reflecting conductive piece are directly reflected to the battery piece, and some light rays are reflected to the front plate and then are secondarily reflected to the battery piece.
Taking the example where the conductive segment includes two reflective surfaces that face away from the contact surface, the included angle formed between the two reflective surfaces needs to satisfy a certain condition, and the angular range thereof will be derived below.
Taking the same two reflecting surfaces as an example, the side length corresponding to the reflecting surface in the cross section is defined as a, the included angle formed by the two reflecting surfaces is alpha, the included angle formed by the reflecting surface and the contact surface is beta, the refractive index n1 of the front plate (such as glass), the refractive index of air is n2, and the critical total internal reflection angle is theta.
In order to reflect the parallel incident light to the surface of the cell as much as possible, the following requirements are satisfied:
1. conditions for direct reflection to the cell:
the angle of incidence is equal to the angle of reflection:
θ1=θ2;
the geometrical relationship shows that:
β=θ1=θ2;
β+β+α=180°;
in order to satisfy the requirement that reflected light is directly reflected to the surface of the cell, the following requirements are satisfied:
θ1+θ2>90°;
i.e. alpha < 90 deg..
2. The total internal reflection condition occurs:
critical angle of in-loop reflection θ c:
θc=arcsin(n2/n1);
the geometrical relationship shows that:
θ=θ1+θ2;
β=θ1=θ2;
β+β+α=180°
in order to satisfy the requirement that the light reflected to the glass is totally reflected to the surface of the cell, the following requirements are satisfied:
θ>θc;
i.e., α < 180 ° - θ c (where θ c is 41.5 °, i.e., α < 138.5 °).
In summary, in order to enable the parallel light beams perpendicularly irradiated to the surface of the cell to be reflected to the surface of the cell, it is necessary to satisfy: alpha is less than 138.5 degrees.
Optionally, alpha is more than or equal to 60 degrees and less than or equal to 138.5 degrees. When α is 60 °, the cross section of the light reflecting section is substantially an equilateral triangle, and when the light reflecting section is used, it is not necessary to distinguish between the contact surface and the light reflecting surface, and any one of the three surfaces can be used as the contact surface.
Optionally, α is more than or equal to 45 degrees and less than or equal to 60 degrees, or α is more than or equal to 60 degrees and less than or equal to 90 degrees, so that light can be directly reflected to the surface of the cell, and absorbed by the cell and converted into photo-generated current.
Optionally, alpha is more than or equal to 90 degrees and less than or equal to 97 degrees, or alpha is more than or equal to 99 degrees and less than or equal to 138.5 degrees, or alpha is more than or equal to 105 degrees and less than or equal to 120 degrees, or alpha is more than or equal to 120 degrees and less than or equal to 138.5 degrees.
According to the embodiment of the application, the light rays are reflected to the surface of the battery by the light reflecting section in the conductive piece, so that the optical utilization rate of the light receiving surface of the photovoltaic battery component is increased, and the power generation power of the component is increased; on the other hand, the non-reflective section is electrically connected with the back surface of the battery, so that the welding reliability between the back surface of the photovoltaic battery and the conductive piece is ensured.
It should be understood that although the present description refers to embodiments, not every embodiment contains only a single technical solution, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the technical solutions in the embodiments can also be combined appropriately to form other embodiments understood by those skilled in the art.
The above list of details is only for the concrete description of the feasible embodiments of the present application, they are not intended to limit the scope of the present application, and all equivalent embodiments or modifications that do not depart from the technical spirit of the present application are intended to be included within the scope of the present application.