Photovoltaic module without bypass diode and shielding working condition operation method thereof

Abstract

The invention relates to the technical field of photovoltaic modules, in particular to a photovoltaic module without a bypass diode and a shielding working condition operation method of the photovoltaic module. Comprising a plurality of photovoltaic cell strings, each photovoltaic cell string is composed of two photovoltaic cell strings connected in parallel, and each photovoltaic cell string is composed of photovoltaic cells with the same number in series; a bus bar and a junction box are also arranged; the positive electrode output of the photovoltaic cell series is connected with the positive electrode of an output cable in the junction box through the bus bar; the cathode output of the photovoltaic cell series is connected with the cathode of an output cable in the junction box through the bus bar; no bypass diode structure is arranged between the positive electrode and the negative electrode of the photovoltaic cell series, and the effects that the photovoltaic module is not provided with the bypass diode, the original operation effect can still be kept under the shielding working condition, and the redundant cost is saved are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic modules, and in particular to a photovoltaic module without bypass diodes and a shielding operation method thereof. Background Art

[0002] In a traditional single-series circuit consisting of a single photovoltaic cell, if there is no bypass diode connected in parallel with the cell string, then when a cell is blocked, the current that the cell can transmit decreases, which will affect the power generation of other good cells in the string. For this reason, traditional photovoltaic modules composed of a single photovoltaic cell generally have three bypass protection diodes, which are evenly divided into a photovoltaic cell string of a module, and one diode is connected in parallel with one-third of the photovoltaic cell string. In theory, one diode in parallel with one photovoltaic cell is the most effective. When this cell or cell string is blocked, the parallel diode will turn on, providing another current path for this cell or cell string. However, due to the cost of diodes and the difficulty of wiring, the industry has generally adopted a compromise solution of connecting one diode in parallel with several photovoltaic cells in series.

[0003] In the design of photovoltaic modules composed of half-cell cells in the prior art, two photovoltaic cells of the same number and specifications are usually connected in series and in parallel to form a group, and then multiple such parallel battery groups are connected in series to form the battery connection structure of the photovoltaic module. In order to prevent some photovoltaic cells from affecting the operation of the entire system due to shading, the design will provide a bypass diode in parallel with the shaded battery group when these parallel groups are conductive. When the photovoltaic cell is shaded, the diode can serve as another path for the battery string current to pass through, while protecting the shaded cell and providing bypass protection.

[0004] However, in the existing bypass diode structure, in a specially designed battery string-parallel connection structure, the two parallel battery strings, when unobstructed, output the two battery paths in parallel. If one path is obstructed, the voltage of the battery string on the obstructed path drops, causing the current in the unobstructed path to flow back to the obstructed battery string. In other words, the voltage difference between the two paths caused by the obstruction forms a new output circuit. In this case, the diode connected in parallel to the battery string cannot be forward-conducted to form a new path, and thus cannot perform additional conduction work, resulting in an ineffective connection. This greatly wastes the relevant components and processing costs. Summary of the Invention

[0005] The purpose of the present invention is to provide a photovoltaic module that does not require a bypass diode and a method for operating the module under shielding conditions in order to address the defects in the prior art, so as to achieve the effect that the photovoltaic module does not need a bypass diode and can still maintain the original operating effect under shielding conditions, thereby saving unnecessary costs.

[0006] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is as follows: it includes a photovoltaic module circuit, the photovoltaic module circuit is composed of a plurality of photovoltaic cells connected in parallel or in series, the photovoltaic cell string is composed of two or more photovoltaic cells connected in parallel, and the photovoltaic cell string is composed of photovoltaic cells of the same number and the same efficiency connected in series; a busbar and a junction box are also provided; the positive output of the photovoltaic cell string is connected to the positive pole of the output cable in the junction box through the busbar; the negative output of the photovoltaic cell string is connected to the negative pole of the output cable in the junction box through the busbar; and no bypass diode is provided between the positive and negative poles of the photovoltaic cell string.

[0007] Furthermore, a laminate assembly is provided, wherein the photovoltaic cell series is provided in the laminate assembly, and the positive and negative outputs of the photovoltaic cell series pass through the back plate structure of the laminate assembly and are connected to the busbar.

[0008] Furthermore, two junction boxes are provided, and the positive output of the photovoltaic cell series in the laminated assembly passes through the backplane structure and is connected to the positive pole of an output cable separately provided in one of the junction boxes via the busbar; the negative output of the photovoltaic cell series passes through the backplane structure and is connected to the negative pole of an output cable separately provided in another junction box via the busbar.

[0009] Furthermore, it also includes a polymer packaging material, which is arranged in the photovoltaic cell series and wraps the photovoltaic cell series.

[0010] Furthermore, the laminated assembly is also provided with a front panel structure, a groove is provided in the middle of the front panel glass, the photovoltaic cell series and the polymer packaging material are arranged in the groove, and the depth of the groove is equal to the thickness of the photovoltaic cell series plus the polymer packaging material during lamination.

[0011] Furthermore, a slope is provided on the edge of the groove, and the slope slopes downward from the outside to the inside; and the groove as a whole is a rectangular structure.

[0012] A photovoltaic module and operating method for operating in shaded conditions without bypass diodes, wherein the photovoltaic cell string is formed by connecting the same number of photovoltaic cells in series, a photovoltaic cell string is formed by connecting two or more photovoltaic cell strings in parallel, and a photovoltaic module circuit is formed by connecting several photovoltaic cell strings in parallel or in series.

[0013] When any number of photovoltaic cells in a photovoltaic cell string are blocked, the remaining photovoltaic cell strings belonging to the same photovoltaic cell string group as the photovoltaic cell string will flow back to the photovoltaic cell string where the blocked photovoltaic cell is located due to the voltage difference, forming an output current of a new string, without causing the diode to conduct forward, thereby providing another path for the blocked cell string, and then the photovoltaic cell string and another photovoltaic cell string maintain a parallel or series current connection;

[0014] The positive and negative outputs of the photovoltaic cell string maintain current connection with the positive and negative poles of the output cable in the junction box through the busbar.

[0015] By including a plurality of photovoltaic cell strings, the photovoltaic cell strings are composed of two parallel photovoltaic cell strings, and the photovoltaic cell strings are composed of the same number of photovoltaic cells connected in series; a bus bar and a junction box are also provided; the positive output of the photovoltaic cell string is connected to the positive pole of the output cable in the junction box through the bus bar; the negative output of the photovoltaic cell string is connected to the negative pole of the output cable in the junction box through the bus bar; the structure of not setting any bypass diode between the positive and negative poles of the photovoltaic cell string and the operating method under shielding conditions, the photovoltaic module is achieved without setting a bypass diode, and can still maintain the original operating effect under shielding conditions, thereby saving unnecessary costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 Schematic diagram of a photovoltaic cell series circuit of the present invention;

[0018] Figure 2 Schematic diagram of the photovoltaic cell series circuit of the present invention when N=2;

[0019] Figure 3 Schematic diagram of a photovoltaic module without bypass diodes according to the present invention without the junction box cover

[0020] Figure 4 This is a schematic diagram of the junction box of the present invention without the cover plate;

[0021] Figure 5 This is a front view of the junction box of the present invention;

[0022] Figure 6A schematic diagram of a photovoltaic module with two junction boxes according to the present invention;

[0023] Figure 7 is a schematic diagram of the interior of a laminate assembly of the present invention;

[0024] Figure 8 2 is a cross-sectional view of a laminate assembly of the present invention.

[0025] Reference numerals:

[0026] Photovoltaic cell string 1, photovoltaic cell string 1-1, busbar 2, junction box 3, laminate assembly 4, backsheet structure 5, polymer encapsulation material 6, frontsheet structure 7, groove 8, slope 9. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0028] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by “center”, “up”, “down”, “left”, “right”, “vertical”, “horizontal”, “inside” and “outside” are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0029] A photovoltaic module without bypass diode, such as Figures 1 to 8 As shown, it includes a photovoltaic module circuit, which is composed of several photovoltaic cell strings 1 connected in parallel or in series. The photovoltaic cell string 1 is composed of more than two photovoltaic cell strings 1-1 connected in parallel, and the photovoltaic cell string 1-1 is composed of photovoltaic cells of the same number and the same efficiency connected in series; a busbar 2 and a junction box 3 are also provided; the positive output of the photovoltaic cell string 1 is connected to the positive pole of the output cable in the junction box 3 through the busbar 2; the negative output of the photovoltaic cell string 1 is connected to the negative pole of the output cable in the junction box 3 through the busbar 2; no bypass diode is provided between the positive and negative poles of the photovoltaic cell string 1.

[0030] Specifically, bypass diodes are essential safety components for preventing hot spot effects during shading. In a structure with two or more parallel photovoltaic cell strings 1-1, when one photovoltaic cell string 1-1 is shaded, the remaining healthy photovoltaic cell strings 1-1 form a reverse current path through the busbar 2, thereby replacing the bypass diode function. Without the bypass diode, the hot spot protection effect is equivalent to that of traditional solutions. In the prior art, bypass diodes are connected in parallel to the entire cell string. When a cell is shaded, the current capacity of the shaded cell decreases, resulting in a current difference with the current generated by the cell string. This causes the shaded cell to become a load, generating a reverse load voltage Vreserve in the opposite direction of the photovoltaic voltage generated by the cell string. When this reverse voltage exceeds the sum of the voltage generated by the cell string and the threshold voltage of the parallel diode (i.e., Vreverse>(N–1)*Voc+Vdth), the diode turns on and begins to operate, forming another current path parallel to the shaded cell. This solves the problem of reduced current capacity of the cell string due to cell shade.

[0031] When one photovoltaic cell string 1-1 in photovoltaic cell string 1 is A and the other is B, cell strings A and B are connected in parallel, and no cells are obstructed, VA = VB = N * Voc, where N is the number of cells connected in series, and Voc is the cell open-circuit voltage. Because the number of cells connected in series and the characteristics of cells in strings A and B are identical, when cell strings A and B are connected in parallel, the voltage across the parallel strings does not generate the diode threshold voltage Vdth, eliminating the need for a bypass diode between the positive and negative electrodes of photovoltaic cell string 1.

[0032] When battery strings A and B are connected in parallel, and any one battery in string A is blocked, the voltage of the battery string drops. The voltage of the battery string with blocked batteries is lower than that of the battery string without blocked batteries. This causes the current of battery string B with high voltage to flow back to battery string A with low voltage, increasing the voltage of battery string A with low voltage, until the voltage of battery string A and battery string B reaches balance again, that is, VA'=VB'.

[0033] VA'=(N-1)*Voc–Vverserve+Idrain*RsA

[0034] VB'=N*Voc–Idrain*RsB

[0035] Since string B only generates photocurrent when there is no shielding, even if all the current generated by string B flows back to string A, the voltage limit of string B is zero. Therefore, the equilibrium state of strings A and B is 0 volts, and no threshold voltage is generated to trigger the diode to turn on. Therefore, when battery strings A and B are connected in parallel, the diode still does not work when the voltage of string B is zero, so that no bypass diode is set between the positive and negative poles of photovoltaic cell string 1.

[0036] When battery strings A and B are connected in parallel, one battery in string A is 100% shaded. This battery cannot pass the string current of the photovoltaic battery string, that is, the current of the photovoltaic string is zero, so that no bypass diode is set between the positive and negative poles of photovoltaic battery string 1.

[0037] Therefore, when any cell is shaded, the shaded cell acts as a load, generating a reverse voltage. This inevitably creates a voltage difference between the two parallel strings, causing current to flow back from the higher voltage side to the lower voltage side, raising the voltage of the shaded cell string and restoring balance between the two strings. Therefore, after a shade event, the automatic energy regulation between the two strings eliminates the need for a bypass diode between the positive and negative electrodes of photovoltaic cell string 1.

[0038] The comparative test of occlusion working conditions is shown in Table 1 below:

[0039]

[0040] Table 1

[0041] Therefore, no bypass diode is required between the positive and negative poles of the photovoltaic cell string 1. The power generation photovoltaic module can save the cost of three diodes and the cost of the middle junction box shell. The remaining junction boxes can therefore be reduced in size, saving part of the box body cost, and also saving diode welding and processing costs.

[0042] As a preferred embodiment of the above, Figures 1 to 8 As shown, a laminate assembly 4 is also provided, the photovoltaic cell string 1 is provided in the laminate assembly 4 , and the positive and negative outputs of the photovoltaic cell string 1 pass through the backboard structure 5 of the laminate assembly 4 and are connected to the busbar 2 .

[0043] Specifically, because no diodes are placed between the positive and negative electrodes of the photovoltaic cell string 1, the backsheet structure 5 does not require holes for the diodes. Instead, the positive and negative outputs of the photovoltaic cell string 1 pass through the backsheet structure 5 of the laminate assembly 4 and connect to the busbar 2. This reduces the number of backsheet perforations, and the laminate assembly 4 directly encapsulates the diode-free circuit, simplifying the lamination process. The laminate assembly 4 and the backsheet structure 5 are simultaneously optimized. The laminate assembly 4 can completely encapsulate the non-protruding circuit, improving structural uniformity, while the backsheet structure 5 only requires minimal perforations for the busbar 2, enhancing sealing reliability.

[0044] As a preferred embodiment of the above, Figures 1 to 8 As shown, two junction boxes 3 are provided, and the positive output of the photovoltaic cell string 1 in the laminate assembly 4 passes through the backboard structure 5 and is connected to the positive pole of the output cable separately provided in one of the junction boxes 3 through the busbar 2; the negative output of the photovoltaic cell string 1 passes through the backboard structure 5 and is connected to the negative pole of the output cable separately provided in another junction box 3 through the other busbar 2.

[0045] Specifically, by not setting a diode between the positive and negative poles of the photovoltaic cell string 1 and directly connecting them to the two junction boxes 3 independently, the diode welding and multi-junction box installation processes are omitted, the shell cost of one of the middle junction boxes is saved, and the remaining junction boxes can be reduced in size.

[0046] As a preferred embodiment of the above, Figures 1 to 8 As shown, it also includes a polymer packaging material 6, which is arranged in the photovoltaic cell string 1 and wraps the photovoltaic cell string 1.

[0047] Specifically, by not setting any bypass diode between the positive and negative electrodes of the photovoltaic cell string 1, the polymer packaging material 6 directly wraps the photovoltaic cell string 1 to form a gapless insulation layer. Since there is no diode heat source, the temperature gradient in the laminated assembly 4 decreases, reducing thermal stress damage; and the polymer packaging material 6 flows more evenly, the vacuum lamination yield of the laminated assembly 4 is improved, and the interface stress between the backboard structure 5 and the packaging material 6 is uniform.

[0048] As a preferred embodiment of the above, Figures 1 to 8 As shown, the laminated assembly 4 is further provided with a front panel structure 7, a groove 8 is provided in the middle of the front panel glass 1, the photovoltaic cell series 1 and the polymer packaging material 6 are arranged in the groove 8, and the depth of the groove 8 is equal to the thickness of the photovoltaic cell series 1 plus the polymer packaging material 6 during lamination.

[0049] Specifically, by not setting any bypass diode between the positive and negative electrodes of the photovoltaic cell string 1, the depth of the groove 8 is precisely matched with the thickness of the photovoltaic cell string 1 + polymer packaging material 6 after lamination, and the surface of the front panel structure 7 is completely flat, thereby eliminating the optical loss caused by the protrusion of the cell string in the traditional solution; the groove 8 restricts the flow range of the polymer packaging material 6 so that there is no risk of glue overflow during lamination; the absence of diode protrusions in the laminated assembly 4 ensures that the vacuum lamination pressure is evenly distributed.

[0050] As a preferred embodiment of the above, Figures 1 to 8 As shown, a slope 9 is provided at the edge of the groove 8, and the slope 9 is inclined downward from the outside to the inside; the groove 8 is a rectangular structure as a whole.

[0051] Specifically, by not setting any bypass diode between the positive and negative poles of the photovoltaic cell series 1, the right-angle boundary of the rectangular groove 8 clearly restricts the flow range of the polymer encapsulation material 6, and the slope 9 guides the polymer encapsulation material 6 to flow toward the center of the groove 8 so that the filling is uniform and bubble-free during lamination.

[0052] A method for operating a photovoltaic module in a shaded condition without a bypass diode, comprising: connecting an equal number of photovoltaic cells in series to form a photovoltaic cell string 1-1; connecting two or more photovoltaic cell strings 1-1 in parallel to form a photovoltaic cell string 1; and connecting a plurality of photovoltaic cell strings 1 in parallel or in series to form a photovoltaic module circuit.

[0053] When any number of photovoltaic cells in a photovoltaic cell string 1-1 are blocked, the remaining photovoltaic cell strings 1-1 belonging to the same photovoltaic cell string 1 as the photovoltaic cell string 1-1 will flow back to the photovoltaic cell string 1-1 where the blocked photovoltaic cell is located due to the voltage difference to form a new string output current, without causing the diode to conduct forward, thereby providing another path for the blocked cell string. Then, the photovoltaic cell string 1 maintains a parallel or series current connection with another photovoltaic cell string 1; the positive and negative outputs of the photovoltaic cell string 1 maintain a current connection with the positive and negative poles of the output cable in the junction box 3 through the busbar 2.

[0054] Specifically, when any cell in photovoltaic cell string 1-1 is blocked, another healthy photovoltaic cell string 1-1 within the same photovoltaic cell string 1 drives current through the voltage difference; this current is then injected back into the blocked string via busbar 2 to form a new output path, completely replacing the traditional diode bypass function and achieving device-free hot spot protection. By forcing a dual-string parallel structure to form a current mutual assistance foundation, busbar 2 is directly connected to junction box 3 to create a low-impedance reverse current path, thereby omitting the bypass diode and forming a new circuit and structure. Therefore, no bypass diode is required between the positive and negative poles of photovoltaic cell string 1. The photovoltaic module can save the cost of three diodes, the cost of one intermediate junction box, and the remaining junction boxes can be reduced in size, saving some box costs. Furthermore, the diode welding and processing costs can be reduced.

[0055] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A photovoltaic module without a bypass diode, characterized by: The invention comprises a photovoltaic assembly circuit, wherein the photovoltaic assembly circuit is composed of a plurality of photovoltaic cell strings (1) connected in parallel or in series, wherein the photovoltaic cell string (1) is composed of two or more photovoltaic cell strings (1-1) connected in parallel, and wherein the photovoltaic cell string (1-1) is composed of photovoltaic cells of the same number and the same efficiency connected in series; A busbar (2) and a junction box (3) are also provided; The positive output of the photovoltaic cell string (1) is connected to the positive electrode of the output cable in the junction box (3) through the busbar (2); The negative electrode output of the photovoltaic cell string (1) is connected to the negative electrode of the output cable in the junction box (3) through the busbar (2); No bypass diode is provided between the positive electrode and the negative electrode of the photovoltaic cell string (1).

2. A photovoltaic module without bypass diode according to claim 1, characterized in that: A laminate assembly (4) is also provided, wherein the photovoltaic cell series (1) is provided in the laminate assembly (4), and the busbar (2) passes through the back plate structure (5) of the laminate assembly (4) and is connected to the positive and negative outputs of the photovoltaic cell series (1).

3. A photovoltaic module without bypass diode according to claim 2, characterized in that: The two junction boxes (3) are provided, and the positive electrode output of the photovoltaic cell string (1) in the laminate assembly (4) passes through the minimalist perforation on the back plate structure (5) through the busbar (2) and is connected to the positive electrode of an output cable separately provided in one of the junction boxes (3); The negative electrode output of the photovoltaic cell string (1) passes through a minimalist perforation on the back plate structure (5) and is connected to the negative electrode of an output cable separately provided in another junction box (3) through another busbar (2).

4. A photovoltaic module without bypass diode according to claim 2, characterized in that: It also includes a polymer packaging material (6), which is arranged outside the photovoltaic cell series (1) and wraps the photovoltaic cell series (1).

5. A photovoltaic module without bypass diode according to claim 4, characterized in that: The laminate assembly (4) is further provided with a front panel structure (7), a groove (8) is provided in the middle of the front panel glass (1), the photovoltaic cell series (1) and the polymer encapsulation material (6) are arranged in the groove (8), and the depth of the groove (8) is equal to the thickness of the photovoltaic cell series (1) plus the polymer encapsulation material (6) during lamination.

6. A photovoltaic module without bypass diode according to claim 5, characterized in that: The edge of the groove (8) is provided with a slope (9), and the slope (9) is inclined downward from the outside to the inside; the groove (8) is a rectangular structure as a whole.

7. A method for operating a photovoltaic module in a shaded condition without a bypass diode, characterized in that: A photovoltaic cell string (1-1) is formed by connecting the same number of photovoltaic cells in series, a photovoltaic cell string (1) is formed by connecting two or more photovoltaic cell strings (1-1) in parallel, and a photovoltaic module circuit is formed by connecting several photovoltaic cell strings (1) in parallel or in series. When any number of photovoltaic cells in a photovoltaic cell string (1-1) are blocked, the remaining photovoltaic cell strings (1-1) belonging to the same photovoltaic cell string (1) as the photovoltaic cell string (1-1) flow back to the photovoltaic cell string (1-1) where the blocked photovoltaic cell is located due to the voltage difference, forming a new string output current without causing the diode to conduct forward, thereby providing another path for the blocked cell string, and then the photovoltaic cell string (1) maintains a parallel or series current connection with another photovoltaic cell string (1); The positive and negative outputs of the photovoltaic cell string (1) maintain current connection with the positive and negative poles of the output cable in the junction box (3) through the busbar (2).

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