Patent Publication Number: US-2019189823-A1

Title: Solar cell photovoltaic module and solar cell photovoltaic assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application s the US national phase of PCT application No. PCT/CN2017/089372 filed on Jun. 21, 2017, which claims priority to Chinese Patent Application No. 201710424871.X, filed with the Chinese Patent Office on Jun. 7, 2017, the disclosures of which are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present disclosure relates to solar cell technical field, and particular to a solar cell photovoltaic module and a solar cell photovoltaic assembly. 
     BACKGROUND OF THE INVENTION 
     With the rise of energy prices, the development and utilization of new energy sources has become the main topic of research in the nowadays energy field. Due to that solar energy has the advantages of no pollution, no regional restrictions, inexhaustible advantages and the like, research on solar power has become the main direction for the development and utilization of new energy sources. Using solar cell to generate electricity is a major way for people to use solar energy nowadays, however, existing solar cell has the following disadvantages. 
     1. The present arrangement of the solar cells is: the spacing between cells is 2 mm, the spacing between strings is 3 mm, the entire blank area of the solar cell assembly is relatively large, and the utilization rate of power generating is low. Although a stacked cell assembly is designed, and the power is improved, the stacked cell assembly increases the usage amount of the cells, and cells of the stacked part cannot generate electricity, resulting in a significant increase in the cost of the assembly, and therefore the cost performance is not high. 
     2. The present conventional assemblies adopt full-piece welding, and the currents of the cells are relatively large, which actually causes that the internal loss of the assemblies increases exponentially, and the power cannot be increased. In order to reduce the internal loss, the interconnectors employed by the design are thickened, and correspondingly, the hidden crack preventing capability of the cells is reduced, and meanwhile the cost of assembly is increased. 
     3. The present battery mainly employs 4 main grids or 5 main grids design, and the widths of the main grids are 1.1 mm and 0.8 mm, respectively, the widths of the main grids are relatively large, which reduces the actual irradiation area of the cells and then reduces the power of the cells; although the 12-grid cell assembly is designed to reduce the widths of the main grids, this assembly has a small welding contact surface, and a high potential risk of reliability, welding strip used in the 12 grid cells is relatively thick, and at present the thickness of most of the used copper wire material is 0.39 mm, which increases by 40% compared with the conventional welding strip with a thickness of 0.27 mm, and in order to reduce hidden crack, the thickness of encapsulating material has to be further increased, thus increasing the cost of the assembly. In addition, the usage amounts of the main grid material and the interconnector material actually used are large, which further increase the cost. If a rounded welding strip is used, there is still a problem that a real surface contact cannot be achieved, resulting a long-term reducing of the reliability of connections between the main grids and the copper-based material actually. The performance of the product is not improved but the risk is. 
     4. In the design of conventional assemblies, the internal circuit is a series structure formed by a plurality of cells, and if an abnormality occurs in one string, the hot spot protection is usually conducted via a diode, and the overall power generation loss relates to the entire string. During the periods of sunrise in the morning and sunset in the afternoon, it faces the waste of power generation by shade, especially the waste of high-efficiency assemblies in this aspect is higher, and therefore, in the case of frequent shade of foreign matter such as bird droppings and leaves, the lack of cleanliness in time which results in the wastage of power generating capacity is a hidden trouble seriously affecting the income of the power station. 
     5. With the further improvement of the efficiency of the cells, the efficiency of the cells has been increased to 19.5% for polycrystalline PERC of mass production, 20.8% for monocrystalline cells, 21% for N-type double-sided cells. and 22.5% for heterojunction cells on average. The operating current of the overall cells rises rapidly. With the application and attenuation, the potential suitability between the cells inside the same assembly increases, with the addition of the external shading or internal hidden cracking and the like of the potential application process, how to improve the suitability of the cells in the assembly becomes a key element of the actual long-term power generation performance. In addition, for the double-sided cell assembly, the difference in the reflective environment at the back results in very great fluctuations and differences in reflection and power generation output, which is a factor that has to face and that results in the difference in suitability of the cells of the assembly during operation. 
     6. At present, in order to solve the abnormalities such as shade of cells or hot spots inside the assembly, the process employed is that a diode is provided between a string and another string, and current shunting and abnormal cell protection are realized through reverse conduction of the diode. However, the start-up of the diode actually separates the string circuit entirely, and reduces the voltage of the entire assembly according to the configuration of the diode proportionally. A local abnormality of a single cell leads to that the entire string of cells does not provide power generation to the working circuit due to being protected by the diode. The damage to power generation capacity is multiplied based on the number of cells of protected strings. In addition, as a centralized inverter circuit, the voltage drop of a single string further affects other parallel string circuits, resulting in the influence and damage of the final output of the combiner box. In addition, there is also an intelligent optimizing chip design for the strings, which monitors the voltage and current of each string and optimizes the string through the chip. This can properly reduce the damage of the string voltage, but it is still an improvement that stays at the string level. The increased cost of string level optimization design is relatively high, and the string level optimization design does not achieve large-scale acceptance in the market in the industry. 
     7. The amount of power generated by the assembly is directly related to the temperature at which the assembly is operating. The higher the operating temperature, the less power generated by the assembly. As described in 5#, the increase of the efficiency of the cells, the raising of the current, and the operating temperature of conventional assembly actually form the restraining factors of the generating capacity. The hot spots or hidden cracking of the assembly in the work process, or the inconformity of the attenuation difference between the cells of the assembly, will lead to internal loss and temperature rise of the assembly, and eventually lead to that the power generation capacity of the assembly cannot be optimized. 
     8. The latest technology of the present assembly is the process design of the overlapped assembly product. There is no welding strip on the surface of the actual overlapped assembly, and under the condition that the cells have hidden cracks, the entire string will suffer from obstructed current output, and the risk of hot spot failure will increase. In addition, the overlapped assembly itself s the cells to overlap and connect with each other to form a circuit for current output. How to compress the inter-cell spacing to close to zero in the assembly design and to improve the conversion efficiency of the assembly, the advantages and the short boards of the overlapped assembly are obvious. 
     SUMMARY OF THE INVENTION 
     The present disclosure provides a solar cell photovoltaic module and a solar cell photovoltaic assembly, to solve the above mentioned technical problems existing in the existing solar cell photovoltaic assemblies. 
     To solve the above mentioned technical problems, the present disclosure provides a solar cell photovoltaic module comprising a plurality of matrix-arranged cells, wherein a plurality of main grids and fine grids are distributed on a light receiving surface of the cells, the main grids collect currents on the fine grids connected thereto, the currents collected by the main grids are transmitted through interconnectors that connect to the main grids, the cells are rectangular, lengths of long sides of the cells are 156-160 mm, lengths of short sides of the cells are 31-54 mm, and the main grids are parallel to the short sides of the cells, and the widths of the main grids are 0.4-0.7 mm, preferably 0.5-0.6 mm. 
     It should be noted that the cells can be obtained by cutting a present conventional cell, for example, dividing a conventional cell along parallel lines parallelly into 2-12 pieces, or directly obtaining cells of a required size through a silicon slice one-time ingot process. 
     In an embodiment, spacing between each two adjacent cells is 0-0.5 mm. 
     In an embodiment, the interconnectors comprise cell-to-cell interconnectors and string-to-string interconnectors, wherein the cell-to-cell interconnectors transport currents on the cells along a direction of the main grids, and the string-to-string interconnectors connect parallel cell-to-cell interconnectors in series. 
     In an embodiment, the cell-to-cell interconnectors are arranged parallel to main grids, and the string-to-string interconnectors perpendicularly intersect the cell-to-cell interconnectors, and connect the cell-to-cell interconnectors intersecting therewith in series. 
     In an embodiment, an end of each cell-to-cell interconnector is a light receiving surface end, and the other end thereof is a back light surface end, the light receiving surface end is connected to one main grid of one cell, the back light surface end is connected to a main grid of a back light surface of another cell, the cell-to-cell interconnector is used to connect two cells in series, and a string-to-string interconnector is welded on the back light surface end. 
     In an embodiment, widths of the cell-to-cell interconnectors are 0.5-0.8 mm, thicknesses thereof are 0.12-0.18 mm, and widths of the string-to-string interconnectors are 0.5-6 mm, thicknesses thereof are 0.1-0.4 mm. 
     In an embodiment, the string-to-string interconnectors employ tinned copper tapes, conductive tapes or transparent conductive films. 
     In an embodiment, a direction parallel to the long sides of the cells is transverse, and a direction parallel to the short sides of the cells is longitudinal, a transverse arrangement, i.e., a number of columns of the matrix-arranged cells is 2-6, and a longitudinal arrangement, i.e., a number of rows of the matrix-arranged cells is 5-40, the string-to-string interconnectors are arranged in a density of every 1-3 row(s) of cells. 
     The present disclosure further provides a solar cell photovoltaic assembly comprising more than two solar cell photovoltaic modules described above and bus bars for collecting currents of the interconnectors. 
     To prevent disconnection of the assembly and thus paralysis resulting from one module failure, in the prior art, two adjacent solar cell photovoltaic modules are generally connected via a diode or via a virtual conductive wire and a diode, and a junction box is connected with an output via the bus bars or the bus bars and the virtual conductive wire. In this way, when one module fails, the connection can through the diode or the virtual conductive wire, that is, the failure module is short-circuited, to ensure the normal operation of other modules. 
     In an embodiment, the solar cell photovoltaic modules are arranged along the long sides of the cells, and the bus bars are parallel to the long sides of the cells. 
     It should be noted that the direction that the long side of the assembly is parallel to the long side of the cell is horizontal, and the direction that the long side of the assembly is parallel to the short side of the cell is vertical. 
     The solar cell photovoltaic module provided by the present disclosure has the following advantages over the prior art: 
     1. The present disclosure employs rectangular cells, the widths of the cells are reduced compared to the conventional cells, that is, the number of rows of the fine grids on a single cell is reduced, the currents collected on the main grids are reduced, and the internal loss is reduced exponentially, so as to increase the generated power. 
     2. In the present disclosure, due to that the side of the cell along the direction of the main grids is short, and thus the currents required to be loaded by the main grids are greatly reduced, the width can be narrowed by 40%, to greatly reduce the shading area of the conductive coating, and to increase the light receiving area of the cell body, to further improve the power generation efficiency; on the other hand, the usage of main grid material (silver paste) is reduced, thereby reduces the production cost. 
     3. Based on the exponential reduction of internal loss described in 1#, narrow and thin interconnector material can be used for current collection. By using interconnectors made of ultra-thin and ultra-soft material, the arrangement of the cells can be realized with a very small spacing for a compact design. The cell spacing is within 0.5 mm, but it does not affect the fragmentation rate and the manufacturing yield of the cells, and avoid the problem of the overlapped assembly that there is a loss due to the overlap and shade between cells, and due to that the interconnectors collect currents, it can better overcome the potential failure resulted from the hidden cracking during the cell application. In this way, the advantage of improving the conversion efficiency of the assembly but not increase the cost is achieved. 
     4. In the present disclosure, spacing between the cells is very small, the blank invalid area is reduced, and the power generation efficiency is further improved by the compact arrangement. 
     5. In the present disclosure, a connection mode of connecting the cells in parallel and then in series is achieved through the sting-to-string interconnectors, and under the condition that one cell is shaded, the current can be continuously transmitted through other cells arranged in parallel therewith, thereby reducing the impact on the whole due to that one single cell is shaded; 
     6. Through the targeted design of the matching of the cell main grid lines and the size of the bar material, combining with the small size of the cells, the overall conventional large current is reduced to a small current, the heat loss index during internal work is reduced, and through balancing the width of the main grid of the cells, the proportion of the front-side silver paste, the width and thickness of the interconnectors, and the final width of light shading, combining with the manufacturing capability of the string welding equipment, the power output of the assembly is maximized, and meanwhile the overall vertical integration cost of the assembly is reduced. 
     7. Through the small current of the small-size cells, and through transverse interconnecting to achieve the bidirectional trends of cells in horizontal and vertical, the side shunt design and process can well solve the above-mentioned suitability difference of the cells of the assembly, and through transverse interconnecting and side shunt, it can also maintain the normal output of the cells without reducing the voltage, achieve a very low external loss, and in particular, bring value for improving the power generation capacity of high-current high-efficiency assembly and long-term inconsistent attenuation. For the potential shades of the assembly in the morning/evening, the power generation capacity of the assembly is continuesly improved. Through the preliminary experimental estimated data, it can be seen that the new design can achieve more than 5% improvement in power generation capacity, especially in the application areas where the ambient temperature is high, and is beneficial for rapidly reducing the cost per kilowatt-hour in the photovoltaic industry. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a structure schematic diagram of a light receiving surface without arranging interconnectors of Embodiment 1; 
         FIG. 2  is a structure schematic diagram of a back light surface of a solar cell photovoltaic module of Embodiment 1; 
         FIG. 3  is a partial structure schematic diagram of a light receiving surface of the solar cell photovoltaic module of  FIG. 2 ; 
         FIG. 4  is a connection schematic diagram between cell-to-cell interconnectors and cells of Embodiment 1; 
         FIG. 5  is a structure schematic diagram of a back light surface of a horizontal type solar cell photovoltaic assembly of Embodiment 2; 
         FIG. 6  is a structure schematic diagram of a back light surface of a vertical type solar cell photovoltaic assembly of Embodiment 3. 
     
    
    
     Wherein: 
       10 —cell;  21 —main grid;  22 —fine grid;  30 —cell-to-cell interconnector;  31 —light receiving surface end;  32 —back light surface end;  33 —string-to-string interconnector. 
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     The exemplary embodiments of the present disclosure are explained in detail combining with the accompanying drawings so that purposes, features and advantages of the present disclosure can be more obvious and more understandable. It should be noted that the drawings of the present disclosure all adopt simplified forms and all use non-precise proportions, and are only used for the purpose of conveniently and clearly explaining the embodiments of the present disclosure. 
     Embodiment 1: Solar Cell Photovoltaic Module 
     A solar cell photovoltaic module provided by the present disclosure comprises, a plurality of matrix-arranged cells, as shown in  FIG. 1 , a light receiving surface of each cell  10  is distributed with four longitudinal main grids  21  and  32  transverse fine grids  22 , of course, the numbers of the main grids  21  and the fines grids  22  may increase or decrease according to requirement, and the present embodiment only gives an example, and the main grids  21  collect currents on the fine grids  22  connected thereto. The cell  10  is obtained by divided a normal cell evenly along  2  transverse parallel lines, that is, ⅓ of the normal cell, and is rectangular, wherein a length L 1  of a long side thereof is 156.75±0.25 mm or is selected in the range of 156-160 mm, a length L 2  of a short side thereof is 52.25±0.25 mm or is selected in the range of 31-54 mm, and the widths d of the main grids is 0.5-0.6 mm, and may broadened to 0.4-0.7 mm. 
     As shown in  FIG. 2 , the solar cell photovoltaic module comprises a plurality of matrix-arranged cells  10 , a direction parallel to the long sides of the cells  10  is transverse, and a direction parallel to the short sides of the cells  10  is longitudinal, a transverse arrangement, i.e., a number of columns of the matrix of the cells  10  is 6, and a longitudinal arrangement, i.e., a number of rows of the matrix of the cells is 7. 
     As shown in  FIG. 3 , enlarging a partial 2×2 matrix of the cells, spacing G between each two adjacent cells both in the transverse direction and in the longitudinal direction is 0-0.5 mm. The currents collected by the main grids  21  are transmitted through interconnectors that connect to the main grids  21 , and the interconnectors are divided into cell-to-cell interconnectors  30  and string-to-string interconnectors  33 . 
     As shown in  FIG. 4 , an end of each cell-to-cell interconnect  30  is a light receiving surface end  31 , and the other end thereof is a back light surface end  32 , as shown in  FIGS. 2-4 , the light receiving surface end  31  is directly welded to one main grid  21  of one cell  10  on the right side, the back light surface end  33  is connected to a main grid  21  of a back light surface of another cell  10  on the left side, and the cell-to-cell interconnect  30  is used to connect the two cells in series. The string-to-string interconnectors  33  perpendicularly intersect the cell-to-cell interconnectors  30 , and the string-to-string interconnect  33  are welded on the back light surface ends  32 , of course, also can be welded on the light receiving surface ends  31 , in the present embodiment, material of the string-to-string interconnectors  33  uses tinned copper tapes, and the string-to-string interconnectors  33  are arranged in a density of every three rows, that is, in every other two rows. 
     Widths of the cell-to-cell interconnectors  30  are in the range of 0.5-0.8 mm, thicknesses thereof are in the range of 0.12-0.18 mm; widths of the string-to-string interconnectors are in the range of 0.5-6 mm, thicknesses thereof are in the range of 0.1-0.4 mm. 
     It should be noted that the string-to-string interconnectors  33  may also use conductive tapes or transparent conductive films, wherein transparent conductive material may interconnected on the back light surface or the light receiving surface, to avoid the influence of the shade by itself. Such a design may be used in a double-sided cell, and may also be used in cell assembly applications such as no main grid process, welding strip process. 
     It should be noted that, for the encapsulation of the cells  10  provided in the present disclosure, double glass process and a narrow frame protection can be combined, to utilize the characteristics of high water resistance, such that the potential leakage of the cells  10  can be solved, and using a narrow frame protection, the convenient installation of assembly, low cost and high reliability can be achieved, especially for the technology of double-sided cells, the requirement of the front and back non-shading installation can resolved. 
     Embodiment 2: Horizontal Solar Cell Photovoltaic Assembly 
     As shown in  FIG. 5 , the horizontal solar cell photovoltaic assembly comprises two solar cell photovoltaic modules  1  arranged side-by-side, that is, arranged along a direction of long sides of the cells  10 , and bus bars  4  for collecting currents of the interconnectors, and the bus bars  4  are parallel to the long sides of the cells  10 , the two solar cell photovoltaic modules I are connected to a virtual conductive wire  5  via diodes (not shown), and the virtual conductive wire  5  may be a conventional thin bus strip. The virtual conductive wire  5  and the cells  10  are isolated by insulating material. The insulating material may be conventional EPE material or a transparent insulating EPC or a transparent backplane, so as to ensure that the virtual conductive wire  5  does not directly contact the cells  10 . A junction box (not shown) is connected with an output through the bus bars  4  and the virtual conductive wire  5 , and here, the junction box adopts a three pin structure, and the working current of an employed single duodiode is between 15 A and 20 A. 
     The solar cell photovoltaic module  1  in the present embodiment differs from that in Embodiment 1 by that the string-to-string interconnectors  33  are arranged in a density of every two rows, that is, in every other row. 
     It is recommended that the double-sided cell assembly uses transparent insulating conductive material and transparent conductive film material. The single-sided cell assembly may directly use non-transparent insulating conductive material and non-transparent conductive film material, directly arranged on the back side. 
     Embodiment 3: Vertical Solar Cell Photovoltaic Assembly 
     As shown in  FIG. 6 , it differs from Embodiment 2 by that, in the solar cell photovoltaic module  1  is arranged side-by-side, the number of columns of the matrix of the cells  10  is 3, and the row thereof is 20. A vertical solar cell photovoltaic assembly is configured. The string-to-string interconnectors  33  are also arranged in a density of every three rows, that is, in every other two rows. 
     It is obvious that those skilled in the art can make various changes or modifications on the present disclosure without depart from scope of the present disclosure. Thus, the present disclosure is also intended to encompass these changes and modifications of the present disclosure which belong to the scope of the claims of the disclosure and equivalents thereof.