A photovoltaic module without bypass diodes
By eliminating the bypass diodes between photovoltaic cell strings in the photovoltaic module and utilizing the automatic adjustment mechanism between the cell strings, the problem of current backflow caused by shading was solved, enabling the photovoltaic module to operate normally under shading conditions, saving costs and simplifying the process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ALPHA SOLAR SUZHOU CO LTD
- Filing Date
- 2025-07-16
- Publication Date
- 2026-06-26
AI Technical Summary
In existing photovoltaic modules, bypass diodes, when connected in parallel with battery strings, cause reverse current and ineffective connections due to shading, resulting in wasted components and increased processing costs.
The photovoltaic module circuit design adopts a photovoltaic cell string, which consists of two or more photovoltaic cells of the same quantity and efficiency connected in series and parallel, and connected by a busbar and junction box. The bypass diodes between the photovoltaic cell strings are eliminated, and the automatic adjustment mechanism between the cell strings is used to maintain the operating effect under shading conditions.
Maintaining normal operation of photovoltaic modules under shading conditions saves on bypass diodes, junction box housings, welding and processing costs, simplifies the lamination process, and improves sealing reliability and module uniformity.
Smart Images
Figure CN224418773U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of photovoltaic modules, and in particular to a photovoltaic module that does not require a bypass diode. Background Technology
[0002] In traditional photovoltaic (PV) modules consisting of a single series circuit composed of a single PV cell, without a bypass diode connected in parallel with the cell string, the reduced current transfer capability of a cell when it is shaded will affect the power generation performance of the other cells in the string. For this reason, traditional PV modules composed of a single PV cell typically use three bypass protection diodes, each distributing a portion of the PV cell string. One diode is connected in parallel to one-third of the PV cell string. Theoretically, one diode in parallel with one PV cell is optimal; when the cell or string is shaded, the parallel diode will conduct, providing an alternative current path for that cell or string. However, due to the cost of diodes and the difficulty of wiring them, the industry has generally adopted a compromise solution of connecting one diode in parallel with several series-connected PV cells.
[0003] In existing photovoltaic module designs using half-cells, two identical photovoltaic cells of the same number and specifications are typically connected in series and parallel to form a group. Then, multiple such parallel cell groups are connected in series to form the cell connection structure of the photovoltaic module. To prevent some photovoltaic cells from affecting the operation of the entire system due to shading, a bypass diode is connected in parallel to these parallel cells to provide conduction. This allows the diode to act as an alternative path for the current to flow through the cell series when the photovoltaic cell is shaded, thus protecting the shaded cell and providing bypass protection.
[0004] However, in existing bypass diode structures, under specially designed parallel battery string connections, the two parallel battery strings output in parallel when unobstructed. If one string is obstructed, the voltage drop in the obstructed string causes current to flow back from the unobstructed string to the obstructed string. This voltage difference between the two strings due to the obstruction creates a new output circuit. In this situation, the diode connected in parallel to the battery strings cannot be forward-biased to form a new path, thus failing to perform the additional conduction work and becoming an ineffective connection. This results in a significant waste of related components and manufacturing costs. Utility Model Content
[0005] The purpose of this invention is to provide a photovoltaic module that does not require a bypass diode, thereby addressing the shortcomings of existing technologies. This allows the photovoltaic module to maintain its original operating performance even under shading conditions without the need for a bypass diode, thus saving unnecessary costs.
[0006] To achieve the above objectives, the technical solution adopted by this utility model is as follows: It includes a photovoltaic module circuit, wherein the photovoltaic module circuit is composed of several photovoltaic cells connected in parallel or series; the photovoltaic cell series 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 efficiency connected in series. It also includes a busbar and a junction box; the positive output of the photovoltaic cell series is connected to the positive terminal of the output cable in the junction box through the busbar; the negative output of the photovoltaic cell series is connected to the negative terminal of the output cable in the junction box through the busbar; and no bypass diode is provided between the positive and negative terminals of the photovoltaic cell series.
[0007] Furthermore, a lamination assembly is also provided, in which the photovoltaic cell series is arranged, and the positive and negative outputs of the photovoltaic cell series pass through the backplate structure of the lamination assembly and are connected to the busbar.
[0008] Furthermore, the two junction boxes are provided. The positive output of the photovoltaic cell string in the laminated assembly passes through the backplate structure and is connected to the positive terminal of a separately provided output cable in one of the junction boxes via the busbar. The negative output of the photovoltaic cell string passes through the backplate structure and is connected to the negative terminal of a separately provided output cable in the other junction box via the other busbar.
[0009] Furthermore, it also includes a polymer encapsulation material, which is disposed within and encapsulates the photovoltaic cell string.
[0010] Furthermore, the laminated assembly also includes a front panel structure with a groove in the middle. The photovoltaic cell string and the polymer encapsulation material are disposed in the groove. The depth of the groove is equal to the thickness of the photovoltaic cell string plus the polymer encapsulation material during lamination.
[0011] Furthermore, the groove edge is provided with a slope, the slope of which slopes downward from the outside to the inside; the groove as a whole has a rectangular structure.
[0012] The system comprises several photovoltaic (PV) cell strings, each consisting of two parallel PV cell strings, and each PV cell string consisting of the same number of PV cells connected in series. It also includes a busbar and a junction box. The positive output of each PV cell string is connected to the positive terminal of an output cable within the junction box via the busbar; the negative output of each PV cell string is connected to the negative terminal of an output cable within the junction box via the busbar. This structure, which eliminates the need for bypass diodes between the positive and negative terminals of the PV cell string, and its operation under shading conditions, achieves the goal of maintaining the original operating performance of the PV module even under shading conditions without the need for bypass diodes, thus saving unnecessary costs. Attached Figure Description
[0013] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0014] Figure 1 This is a schematic diagram of the photovoltaic cell series circuit of this utility model;
[0015] Figure 2 This is a schematic diagram of the photovoltaic cell series circuit of this utility model when N=2;
[0016] Figure 3 This is a schematic diagram of the photovoltaic module of this utility model that does not require a bypass diode, with the junction box cover removed.
[0017] Figure 4 A schematic diagram of the junction box of this utility model without the cover plate;
[0018] Figure 5 This is a front view of the junction box of this utility model;
[0019] Figure 6 These are schematic diagrams of photovoltaic modules for two junction box schemes of this utility model;
[0020] Figure 7 This is a schematic diagram of the internal structure of the lamination assembly of this utility model;
[0021] Figure 8 This is a cross-sectional view of the laminated component of this utility model.
[0022] Figure label:
[0023] Photovoltaic cell string 1, photovoltaic cell string 1-1, busbar 2, junction box 3, laminated module 4, backsheet structure 5, polymer encapsulation material 6, front panel structure 7, groove 8, ramp 9. Detailed Implementation
[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.
[0025] In the description of this utility model, it should be noted that the orientation or positional relationship indicated by terms such as "center", "up", "down", "left", "right", "vertical", "horizontal", "inner", and "outer" are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0026] A photovoltaic module that does not require a bypass diode, such as Figures 1-8 As shown, the system includes a photovoltaic module circuit, which consists of several photovoltaic cell strings 1 connected in parallel or in series. Each photovoltaic cell string 1 is composed of two or more photovoltaic cell strings 1-1 connected in parallel, and each photovoltaic cell string 1-1 is composed of photovoltaic cells of the same number and 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 terminal 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 terminal of the output cable in the junction box 3 through the busbar 2. No bypass diodes are provided between the positive and negative terminals of the photovoltaic cell string 1.
[0027] Specifically, the bypass diode is an essential safety component to prevent hot spot effects during shading. In a structure of two or more parallel photovoltaic strings 1-1, when one photovoltaic string 1-1 is shaded, the remaining normal photovoltaic strings 1-1 form a reverse current path through bus 2, thus replacing the function of the bypass diode. Omitting the bypass diode results in equivalent hot spot protection as with traditional solutions. In the existing technology, the parallel bypass diode operation mode of the entire battery string works as follows: when a battery is shaded, the current-carrying capacity of the shaded battery decreases, creating a difference between the current generated by the battery string and the current generated by the battery string. This causes the shaded battery to become a load, generating a reverse load voltage Vreserve, opposite in direction to the photovoltaic voltage generated by the battery string. When the value of this reverse voltage exceeds the sum of the voltage generated by the battery string and the threshold voltage of the parallel diode (i.e., Vreverse > (N-1)*Voc + Vdth), the diode turns on and begins to work, forming another current path parallel to the shaded battery. This solves the problem of reduced current-carrying capacity of the battery string due to battery shading.
[0028] When one photovoltaic cell string 1 is A and the other is B, the A and B strings are connected in parallel, and no cells are shaded. In this case, VA = VB = N * Voc, where N is the number of cells connected in series and Voc is the open-circuit voltage of the cell. Since the number of cells connected in series and the characteristics of the cells in strings A and B are exactly the same, when the A and B strings are connected in parallel, the voltage of the parallel cell strings does not generate a diode threshold voltage Vdth. Therefore, no bypass diode is required between the positive and negative terminals of photovoltaic cell string 1.
[0029] When battery strings A and B are connected in parallel, if any battery in string A is blocked, the voltage of the string drops. The voltage of the blocked string is lower than that of the unblocked string. This causes current to flow from the higher-voltage string B to the lower-voltage string A, increasing the voltage of string A until the voltages of strings A and B are balanced again, i.e., VA' = VB'.
[0030] VA'=(N-1)*Voc-Vverserve+Idrain*RsA
[0031] VB'=N*Voc-Idrain*RsB
[0032] Since the cells in string B only generate photocurrent when there is no shading, 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 conduct. Thus, when 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 terminals of photovoltaic cell string 1.
[0033] When battery strings A and B are connected in parallel, and one battery in string A is 100% shaded, this battery will not be able to carry the series current of the photovoltaic string, meaning the current of the photovoltaic string is zero. Therefore, no bypass diode is required between the positive and negative terminals of photovoltaic string 1.
[0034] Therefore, when any cell is shaded, the shaded cell becomes a load and generates a reverse voltage, which will inevitably create a voltage difference between the two parallel cell strings. This causes current to flow from the side with the higher voltage to the side with the lower voltage, increasing the voltage of the shaded cell string and restoring balance between the two strings. Thus, after shading, the automatic energy adjustment between the two strings eliminates the need for any bypass diodes between the positive and negative terminals of photovoltaic cell string 1.
[0035] The comparison test results under shading conditions are shown in Table 1 below:
[0036]
[0037] Table 1
[0038] Therefore, by eliminating the need for any bypass diodes between the positive and negative terminals of the photovoltaic cell series 1, the photovoltaic module can save the cost of three diodes, the cost of one junction box housing, and the remaining junction box can be reduced in size, saving some housing costs. Furthermore, it can also save on diode welding and processing costs.
[0039] As a preferred embodiment of the above, such as Figures 1-8 As shown, a lamination assembly 4 is also provided, and the photovoltaic cell string 1 is disposed in the lamination assembly 4. The positive and negative outputs of the photovoltaic cell string 1 pass through the back plate structure 5 of the lamination assembly 4 and are connected to the busbar 2.
[0040] Specifically, since no diodes are placed between the positive and negative terminals of the photovoltaic cell series 1, the backplate structure 5 does not need to have holes for diodes. The positive and negative outputs of the photovoltaic cell series 1 pass through the backplate structure 5 of the laminated assembly 4 and connect to the busbar 2, reducing the number of holes in the backplate. The laminated assembly 4 directly wraps the diode-free circuit, simplifying the lamination process. The laminated assembly 4 and the backplate structure 5 are optimized simultaneously. The laminated assembly 4 can completely wrap the protrusion-free circuit, improving structural uniformity. The backplate structure 5 only needs to provide minimal holes for the busbar 2, enhancing sealing reliability.
[0041] As a preferred embodiment of the above, such as Figures 1-8 As shown, two junction boxes 3 are provided. The positive output of the photovoltaic cell string 1 in the laminated assembly 4 passes through the back plate structure 5 and is connected to the positive terminal of a separately provided output cable in one of the junction boxes 3 via the busbar 2. The negative output of the photovoltaic cell string 1 passes through the back plate structure 5 and is connected to the negative terminal of a separately provided output cable in the other junction box 3 via the other busbar 2.
[0042] Specifically, by not placing diodes between the positive and negative terminals of the photovoltaic cell series 1 and directly connecting them to two junction boxes 3 independently, the diode soldering and multiple junction box installation processes are eliminated, saving the housing cost of one middle junction box, and the remaining junction boxes can be reduced in size.
[0043] As a preferred embodiment of the above, such as Figures 1-8 As shown, it also includes a polymer encapsulation material 6, which is disposed within the photovoltaic cell string 1 and encapsulates the photovoltaic cell string 1.
[0044] Specifically, by not setting any bypass diodes between the positive and negative electrodes of the photovoltaic cell string 1, the polymer encapsulation material 6 directly wraps the photovoltaic cell string 1 to form a gapless insulating layer. Since there is no diode heat source, the temperature gradient inside the laminated component 4 decreases, reducing thermal stress damage. Furthermore, the polymer encapsulation material 6 flows more uniformly, the vacuum lamination yield of the laminated component 4 is improved, and the interface stress between the backsheet structure 5 and the encapsulation material 6 is uniform.
[0045] As a preferred embodiment of the above, such as Figures 1-8 As shown, the laminated assembly 4 is further provided with a front panel structure 7, and a groove 8 is provided in the middle of the front panel structure 7. The photovoltaic cell string 1 and the polymer encapsulation material 6 are disposed in the groove 8. The depth of the groove 8 is equal to the thickness of the photovoltaic cell string 1 plus the polymer encapsulation material 6 during lamination.
[0046] Specifically, by not placing any bypass diodes 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 encapsulation 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 encapsulation material 6, so there is no risk of glue overflow during lamination; the absence of diode protrusions in the laminated component 4 ensures uniform pressure distribution during vacuum lamination.
[0047] As a preferred embodiment of the above, such as Figures 1-8 As shown, the groove 8 has a ramp 9 at its edge, and the ramp 9 slopes downward from the outside to the inside; the groove 8 is a rectangular structure as a whole.
[0048] Specifically, no bypass diodes are placed between the positive and negative electrodes of the photovoltaic cell series 1. The right-angled boundary of the rectangular groove 8 clearly constrains the flow range of the polymer encapsulation material 6. The slope of the ramp 9 guides the polymer encapsulation material 6 to flow towards the center of the groove 8, so that the filling is uniform and bubble-free during lamination.
[0049] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.
Claims
1. A photovoltaic module that does not require a bypass diode, characterized in that: The photovoltaic module circuit is composed of several photovoltaic cell strings (1) connected in parallel or in series. The photovoltaic cell string (1) is composed of two or more photovoltaic cell strings (1-1) connected in parallel. The photovoltaic cell string (1-1) is composed of photovoltaic cells of the same number and the same efficiency connected in series. It is also equipped with a busbar (2) and a junction box (3); The positive output of the photovoltaic cell series (1) is connected to the positive terminal 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 terminal of the output cable in the junction box (3) through the busbar (2); No bypass diodes are provided between the positive and negative terminals of the photovoltaic cell string (1).
2. A photovoltaic module without a bypass diode according to claim 1, characterized in that, A lamination assembly (4) is also provided, the photovoltaic cell string (1) is disposed in the lamination assembly (4), and the busbar (2) passes through the back plate structure (5) of the lamination assembly (4) and is connected to the positive and negative outputs of the photovoltaic cell string (1).
3. A photovoltaic module without a bypass diode according to claim 2, characterized in that, The two junction boxes (3) are provided. The positive output of the photovoltaic cell string (1) in the laminated assembly (4) passes through the busbar (2) through the minimal perforation on the back plate structure (5) and is connected to the positive terminal of the output cable separately provided in one of the junction boxes (3). The negative output of the photovoltaic cell string (1) passes through a minimal perforation on the backplate structure (5) and is connected to the negative terminal of a separately provided output cable in another junction box (3) via another busbar (2).
4. A photovoltaic module without a bypass diode according to claim 2, characterized in that, It also includes a polymer encapsulation material (6), which is disposed outside the photovoltaic cell string (1) and wraps the photovoltaic cell string (1).
5. A photovoltaic module without a bypass diode according to claim 4, characterized in that, The laminated assembly (4) is also provided with a front panel structure (7), and a groove (8) is provided in the middle of the front panel structure (7). The photovoltaic cell string (1) and the polymer encapsulation material (6) are provided in the groove (8). The depth of the groove (8) is equal to the thickness of the photovoltaic cell string (1) plus the polymer encapsulation material (6) during lamination.
6. A photovoltaic module without a bypass diode according to claim 5, characterized in that, The groove (8) has a ramp (9) at its edge, and the ramp (9) slopes downward from the outside to the inside; the groove (8) is a rectangular structure as a whole.