A method for determining the current of a bypass device of a photovoltaic module and a photovoltaic module

Abstract

The application relates to a current determination method of a photovoltaic module bypass device and a photovoltaic module. The current determination method of the photovoltaic module bypass device comprises the following steps: obtaining multiple proportional relationships between maximum average forward rectification currents of bypass devices in test photovoltaic modules and short circuit currents of the test photovoltaic modules by separately testing the test photovoltaic modules under various different shading conditions; and determining the value of the maximum average forward rectification current required by the bypass device arranged in a target photovoltaic module based on the proportional relationships and the short circuit current of the target photovoltaic module obtained through testing, so that the maximum current value required by the bypass device in the photovoltaic module is reduced, and the manufacturing cost of the photovoltaic module is reduced.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a method for determining the current of a photovoltaic module bypass device and a photovoltaic module. Background Technology

[0002] Bypass diodes are a common method for preventing hot spots in photovoltaic (PV) modules. When a cell is shaded, the corresponding current flowing through the circuit is redirected from the cell to the bypass diode. Due to the increase in cell size and efficiency, the operating current and short-circuit current of PV systems are also gradually increasing. Taking the currently mainstream 182-inch rectangular cell as an example, the short-circuit current of a PV module can reach 16.3A, while for larger cells, the short-circuit current can reach 18.6A.

[0003] Because photovoltaic (PV) modules need to operate outdoors for over twenty years, for current technology, the matching bypass diodes generally need to consider, at least the bifaciality of the PV module (the impact of backlighting on power generation) and situations where the light intensity exceeds the short-circuit current test value, in addition to the short-circuit current. The short-circuit current test corresponds to 1000 W / m. 2 In reality, under good lighting conditions, the light intensity can reach 1200W / m². 2 Even 1300W / m 2 The situation.

[0004] Currently, the maximum average forward rectified current (IF) requirement for general diodes is greater than the photovoltaic module's short-circuit current Isc × 1.3 × 1.25. For a short-circuit current of 18.6A, this corresponds to 18.6 × 1.3 × 1.25 = 30.225A. A common practice is to use a 35A bypass diode to match the photovoltaic module. As cell size continues to increase, short-circuit current will also continue to increase, thus increasing the maximum average forward rectified current requirement for bypass diodes, leading to increased photovoltaic module costs. There is also a difficulty in supplying diodes for modules with such high current requirements. If more complex bypass devices such as photovoltaic optimizers and smart device integrations are used for hot spot prevention, the increased current requirements will significantly impact the cost of photovoltaic modules. Summary of the Invention

[0005] Therefore, it is necessary to provide a method for determining the current of a photovoltaic module bypass device and a photovoltaic module to address the above-mentioned technical problems.

[0006] In a first aspect, embodiments of this application provide a method for determining the current of a bypass device in a photovoltaic module, wherein the photovoltaic module includes a power generation body and a bypass device connected in parallel with the power generation body, and the method includes:

[0007] The photovoltaic modules were individually tested under various shading conditions to obtain multiple proportional relationships between the maximum average forward rectified current of the bypass device and the short-circuit current of the photovoltaic modules.

[0008] Based on the aforementioned proportional relationships and the short-circuit current of the target photovoltaic module obtained from the test, the value of the maximum average forward rectified current required by the bypass device installed in the target photovoltaic module is determined.

[0009] In one embodiment, the step of individually testing the photovoltaic module under various shading conditions to obtain multiple proportional relationships between the maximum average forward rectified current of the bypass device and the short-circuit current of the photovoltaic module includes:

[0010] The photovoltaic module was tested individually under various shading conditions to obtain multiple sets of operating current values ​​of the bypass device and the maximum power point current of the photovoltaic module.

[0011] Based on the maximum power point current of the test photovoltaic module obtained under various shading conditions, the short-circuit current of the test photovoltaic module under various shading conditions is determined.

[0012] Based on the short-circuit current of the tested photovoltaic module under various shading conditions and the corresponding operating current value of the bypass device, several proportional relationships between the maximum average forward rectified current of the bypass device and the short-circuit current of the tested photovoltaic module are determined.

[0013] In one embodiment, the maximum average forward rectified current of the bypass device is between 1.6 times the short-circuit current of the target photovoltaic module and greater than or equal to 0.5 times the short-circuit current of the target photovoltaic module.

[0014] In one embodiment, the maximum average forward rectified current of the bypass device is between 1 times the short-circuit current of the target photovoltaic module and greater than or equal to 0.5 times the short-circuit current of the target photovoltaic module.

[0015] In one embodiment, the atmospheric quality is AM1.5, the ambient temperature is 25°C, and the irradiance is 1000 W / m². 2 Under illumination, the target photovoltaic module is short-circuited and then tested to obtain the short-circuit current of the target photovoltaic module.

[0016] In one embodiment, the individual testing of the photovoltaic modules under various shading conditions includes:

[0017] The photovoltaic modules were tested individually under cloud cover conditions, simulated bird droppings cover conditions, and simulated shadow cover conditions.

[0018] Secondly, embodiments of this application also provide a photovoltaic module, including multiple cell groups and bypass devices connected in parallel with each of the cell groups, wherein the maximum average forward rectified current value of each bypass device is determined by the method described in the first aspect above.

[0019] In one embodiment, each of the battery cell groups includes multiple battery strings, and the battery cells in each battery string are connected in series with each other through a conductive material. The battery strings are connected in series and parallel to form the battery cell group.

[0020] In one embodiment, the battery cell is a half-cell battery, a three-cell battery, a four-cell battery, or a six-cell battery.

[0021] In one embodiment, the bypass device includes a Schottky diode or a photovoltaic optimizer.

[0022] The aforementioned method for determining the current of the bypass device in a photovoltaic module and the photovoltaic module itself involve individually testing the photovoltaic module under various shading conditions to obtain multiple proportional relationships between the maximum average forward rectified current of the bypass device in the test photovoltaic module and the short-circuit current of the test photovoltaic module. Based on these proportional relationships and the short-circuit current of the target photovoltaic module obtained from the tests, the maximum average forward rectified current required by the bypass device in the target photovoltaic module is determined, thereby reducing the maximum current required by the bypass device in the photovoltaic module and lowering the manufacturing cost of the photovoltaic module.

[0023] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0024] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0025] Figure 1 This is an exploded view of a typical photovoltaic module structure in one embodiment;

[0026] Figure 2 This is an electrical schematic diagram of a typical photovoltaic module in one embodiment;

[0027] Figure 3 This is a flowchart illustrating a method for determining the current of a photovoltaic module bypass device in one embodiment;

[0028] Figure 4 This is an electrical schematic diagram of a photovoltaic module being tested in one embodiment. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this application clearer, the application is described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. All other embodiments obtained by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0030] Obviously, the accompanying drawings described below are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar scenarios based on these drawings without any inventive effort. Furthermore, it is understood that although the efforts made in this development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, any changes to design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as insufficient disclosure of the content of this application.

[0031] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0032] The following is an explanation of the current parameters appearing in this application:

[0033] Maximum average forward rectified current (IF): This refers to the maximum average forward current allowed when a diode operates for an extended period. This current is determined by the junction area of ​​the PN junction and heat dissipation conditions. The average current flowing through the diode during operation must not exceed this value.

[0034] Short-circuit current (Isc): refers to the current measured when a photovoltaic module experiences a short circuit.

[0035] Maximum power point current (Imp): refers to the current generated by a photovoltaic module when it operates at its maximum power point. Its value is always less than the short-circuit current (Isc).

[0036] like Figure 1The diagram shown is an exploded view of a typical photovoltaic module structure, including: front glass / panel 10, laminated glass 20, metal interconnect 30, cell 40, laminated glass 50, back glass / panel 60, frame 70, junction box 80, and cable connector 90. Figure 1 This includes the main structure and corresponding positions of the laminate. In the specific process, the power generation cells are first welded together to form a battery string using welding strips. Then, the welding strips and busbars are welded together to form the interconnection between the battery strings. Next, the front glass / panel, corner glass, and back glass / panel are stacked together in sequence. The stacked product is placed in a laminator. Through the high temperature and vacuum of the laminator, the interlayer material melts and the gas inside the laminate is expelled. After lamination, the overflowing interlayer material and residual material are cut off. After processing, the laminate undergoes a frame installation process (framing process). The framing process requires applying adhesive (silicone) to the cavity in a specific position on the upper part of the frame and using a framing machine to snap and fix the frame to the laminate.

[0037] Figure 2 This is a typical electrical schematic diagram of a photovoltaic module. You can see that the photovoltaic module consists of 12 battery strings (6 strings at the top and 6 strings at the bottom, with one bypass diode at each of the three positions in the middle, left, center, and right. Each diode drives 4 battery strings, which are formed by two battery strings connected in series and then connected in parallel with the other two battery strings). These strings are connected in series and parallel through busbars to form a whole, located at the top, center, and bottom of the module.

[0038] This application provides a method for determining the current of a bypass device in a photovoltaic module. The photovoltaic module includes a power generation main body and a bypass device connected in parallel with the power generation main body, such as... Figure 3 As shown, the method includes the following steps:

[0039] Step 201: Perform individual tests on the photovoltaic module under various shading conditions to obtain multiple proportional relationships between the maximum average forward rectified current of the bypass device and the short-circuit current of the photovoltaic module.

[0040] like Figure 4 The diagram shown is an example electrical schematic of a photovoltaic module for testing. It includes a power generation body 100 composed of battery cells and a bypass diode 200. The battery cells are 182-size half-cell cells, with 24 cells connected in series on the top and bottom, and the cells are connected in parallel in the top and bottom arrays. A bypass diode 200 is also connected in parallel. The short-circuit current Isc obtained by the photovoltaic module for testing according to the IEC standard is 13.81A. The photovoltaic module for testing is connected to a photovoltaic system composed of the same cells for testing.

[0041] The testing methods of this application include two types: long-term application environment tracking test and human influence test. The test photovoltaic modules are tested separately under natural environment cloud cover conditions, simulated bird droppings cover conditions, and simulated shadow (building, plant) cover conditions to obtain multiple proportional relationships between the maximum average forward rectified current of the bypass device and the short-circuit current of the test photovoltaic module under various cover conditions.

[0042] The long-term application environment tracking test is detailed as follows:

[0043] In summer, the highest light intensity can reach 1100W / m². 2 In certain regions, the maximum current of the bypass diodes in natural environments was tracked over a long period. This situation corresponds to the shading effect of climate on photovoltaic modules (the effect of cloudy weather). Through long-term observation, it was found that, under normal circumstances, the bypass diodes of photovoltaic modules do not conduct. This is because the clouds in the sky are large and generally affect all photovoltaic modules in the system quickly, meaning that the light intensity of all photovoltaic modules in the system is reduced. Therefore, in this case, the shading effect applies to all system modules, and the overall reduction in light intensity does not cause the diodes to start. Secondly, although some modules in the system may be shaded, in this case, because the clouds are high, there is transmission and scattering of light during transmission. The difference in light intensity between adjacent shaded and unshaded photovoltaic modules is not significant, similar to the situation under slight shading conditions, and the bypass diodes of the photovoltaic modules will not conduct.

[0044] In special circumstances, such as when a thick, small cloud cover obstructs the photovoltaic (PV) module, after several months of testing, the diode's operating current did not exceed 0.3 times the maximum power point current (Imp) of the tested PV module. Furthermore, in such situations, the maximum power point current (Imp) of the tested PV module in practical applications is often much smaller than 0.6 times the Imp under the standard test light intensity (i.e., the light intensity is often not strong under these conditions). Therefore, without special obstruction, the actual maximum average forward rectified current (IF) of the diode only needs to be 0.18 times the maximum power point current (Imp) under the standard test light intensity to be sufficient.

[0045] Because light intensity varies during outdoor testing, this application uses the maximum power point current Imp of the tested photovoltaic module as a benchmark, and then converts it into a percentage of the short-circuit current Isc of the tested photovoltaic module. Based on empirical statistics, the maximum power point current Imp of the tested photovoltaic module is approximately 90% of the short-circuit current Isc, i.e., 0.18Imp = 0.16Isc. This means that under these test conditions, the maximum average forward rectified current of the bypass device is equal to 0.16 times the short-circuit current of the tested photovoltaic module.

[0046] To further understand the impact of shading conditions such as buildings, plants, and bird droppings on photovoltaic modules, the operating current levels of the diodes in a half-cell photovoltaic module under different shading conditions were also tested. Please refer to [link / reference]. Figure 4 There are three paths for current to flow in a photovoltaic module: the upper photovoltaic cell string connected in parallel, the lower photovoltaic cell string, and the diode circuit. During normal operation, the diodes are off. When the module is shaded, the bypass diodes activate, acting as a current shunting circuit.

[0047] In photovoltaic (PV) modules, the severity of shading and its impact on diode current are determined by the most severely shaded cell, a phenomenon known as the "barrel effect." Testing revealed that after a PV module cell is shaded, current does not cease flowing through the shaded cell. Instead, the current flow is related to the shading conditions, roughly corresponding one-to-one. For example, if the most severely shaded cell in the upper half is 80% shaded, the current in the upper half will decrease by approximately 80%. The current flowing through the diode is a portion of this reduced current. For instance, under normal operating conditions, the PV module's short-circuit current Isc is 11A, and the operating current Imp is 10A. With 80% shading in the upper half, and the lower half of the module operating normally, the upper half loses 4A of current. This 4A is diverted through the diode and the lower half current, keeping the overall PV module operating current at 10A (the lower half has limited absorption capacity, typically only absorbing about 15% under extreme conditions; the rest needs to be absorbed by the diode).

[0048] The simulated bird droppings test is as follows:

[0049] Bird droppings are often unavoidable. Through observation and testing, the impact of bird droppings is mainly to block local batteries. According to the observation, the degree of blockage is generally no more than 25% for the most severely affected batteries (i.e., the maximum light blocking ratio of a single battery does not exceed 25%). Although there are cases where the blocked area is greater than 1 / 4, large areas of bird droppings still have a certain light transmittance. Therefore, it is reasonable to calculate the maximum current loss as 25% overall. In extreme cases, assuming that bird droppings block both the upper and lower parts at the same time, the limit is only at the 40% Imp level (Imp is about 90% of Isc).

[0050] Therefore, the maximum diode current caused by animal effects such as bird droppings is 0.9Isc × 40% = 0.36Isc. Meanwhile, for bifacial photovoltaic modules, the presence of obstructions on the back side can be ignored; only the case where the maximum light intensity exceeds the standard light intensity needs to be considered, i.e., 0.36Isc × 1.25 = 0.45Isc.

[0051] Finally, considering the combined effects of clouds and bird droppings, the hot spots on the photovoltaic modules lead to a surge in the maximum operating current of the diodes, resulting in a synchronous mutual influence of 0.45Isc + 0.16Isc = 0.61Isc. In areas with favorable climates, few birds, and no vegetation or buildings providing shade, a maximum diode operating current of 0.5Isc is actually sufficient.

[0052] The simulated building and plant shadow tests are as follows:

[0053] One or more batteries at the top or bottom were shielded with a material with a certain light transmittance. In this case, a light shielding effect of more than 30% is required to cause the diode to conduct (some slight differences in shielding, such as a distant utility pole, or some thin clouds, will not cause the diode to conduct). The test results are shown in Table 1.

[0054] Table 1

[0055]

[0056] To study the extreme cases, the most stringent shading conditions were directly used during the test, and the test results are shown in Table 2. Since the light intensity varies during outdoor testing, the maximum power point current Imp of the tested photovoltaic module was used as the benchmark, and finally converted into a percentage of the short-circuit current Isc.

[0057] Table 2

[0058]

[0059] As can be seen from Table 2, when half of the module is covered by a completely black material, the diode current is less than 1 / 2 of Imp. Only when the entire module is completely covered by an opaque material will the diode current approach Imp. Even when using an almost opaque tarpaulin for covering, the diode current is only 77% of Imp. After raising the tarpaulin (the shadow at least covers the entire module), the diode current drops rapidly to 69% of Imp.

[0060] The data above shows that in photovoltaic application environments, the light transmittance of general buildings / plants is unlikely to block photovoltaic modules by more than 70%. The extreme case is considered to be the most severe situation, in which the diode operating current is 0.69×Imp=0.69×Isc×0.9=0.62Isc.

[0061] Similarly, considering the effects of bird droppings and weather, since the impact of weather generally does not exceed the impact of obstructions, from this perspective, the impact of clouds is negligible when there are building obstructions. Similarly, the impact from the back is also basically negligible. The effects of bird droppings and obstructions can be partially offset. In general, in complex application environments, the actual maximum average forward rectified current IF of the diode will not exceed 1 times the short-circuit current Isc of the photovoltaic module.

[0062] Step 202: Based on the aforementioned proportional relationships and the short-circuit current of the target photovoltaic module obtained from the test, determine the value of the maximum average forward rectified current required by the bypass device installed in the target photovoltaic module.

[0063] The existing technology requiring the bypass diode of a photovoltaic module to have an IF ≥ 1.3 × 1.25 × Isc = 1.625Isc is actually overly redundant. Based on the test results above, it is known that under ideal operating conditions, a maximum average forward rectified current IF of 0.5 times Isc is generally sufficient, and even under more complex conditions, a value of 1 times Isc is generally adequate. This application can determine the maximum average forward rectified current required for the bypass device in the target photovoltaic module based on the measured ratios and the short-circuit current of the target photovoltaic module, combined with the actual operating environment of the photovoltaic module.

[0064] This application determines the current value of the diode under normal operating conditions through actual testing, and clarifies the current value of the bypass diode under various shading conditions. This clarifies how much current flows into the diode under actual conditions, thereby determining the maximum average forward rectified current required by the bypass diode. This reduces the maximum current required by the bypass device in the photovoltaic module, thus lowering the manufacturing cost of the photovoltaic module.

[0065] With future advancements in photovoltaic technology, the Imp and Isc values ​​of photovoltaic modules will increase. Designing bypass current requirements based on actual application conditions can effectively reduce costs and expand applicability, especially for more complex bypass devices, such as electrical equipment that combines optimization, intelligence, and inverter functions for transmitting control information from photovoltaic modules. This intelligent entity is integrated with the bypass function; effectively reducing the bypass current requirements can correspondingly reduce the current requirements of the intelligent entity to some extent.

[0066] In one embodiment, the step of individually testing the photovoltaic module under various shading conditions to obtain multiple proportional relationships between the maximum average forward rectified current of the bypass device and the short-circuit current of the photovoltaic module includes the following steps:

[0067] Step 301: Perform individual tests on the photovoltaic module under various shading conditions to obtain multiple sets of operating current values ​​of the bypass devices and the maximum power point current of the photovoltaic module.

[0068] Step 302: Based on the maximum power point current of the test photovoltaic module obtained under various shading conditions, determine the short-circuit current of the test photovoltaic module under various shading conditions.

[0069] Since the light intensity changes during outdoor testing, the maximum power point current Imp of the tested photovoltaic module is used as the benchmark. Finally, based on the ratio of Imp to Isc, it is converted into the corresponding short-circuit current.

[0070] Step 303: Based on the short-circuit current of the test photovoltaic module under various shading conditions and the corresponding operating current value of the bypass device, determine several proportional relationships between the maximum average forward rectified current of the bypass device and the short-circuit current of the test photovoltaic module.

[0071] In one embodiment, the maximum average forward rectified current of the bypass device is between 1.6 times and greater than or equal to 0.5 times the short-circuit current of the target photovoltaic module.

[0072] The test results above show that, under ideal application conditions, a maximum average forward rectified current IF of 0.5 times Isc is generally sufficient. Under relatively complex conditions, a value of 1 times Isc is also generally sufficient. To improve the applicability of the bypass device and reduce its cost, this embodiment sets the maximum average forward rectified current of the bypass device to 1.6 times the short-circuit current of the target photovoltaic module. Compared to the existing 1.625Isc, this is sufficient for use in photovoltaic modules under various extreme shading environments, thus reducing the cost of the photovoltaic module.

[0073] In one embodiment, the maximum average forward rectified current of the bypass device is between 1 times the short-circuit current of the target photovoltaic module and greater than or equal to 0.5 times the short-circuit current of the target photovoltaic module.

[0074] Based on the above test results, it can be seen that under the condition of good actual application environment, the condition of the maximum average forward rectified current IF being 0.5 times Isc can basically meet the requirements, and under the condition of relatively complex environment, the condition of Isc being 1 times can also basically meet the requirements.

[0075] In one embodiment, the atmospheric quality was AM1.5, the ambient temperature was 25°C, and the irradiance was 1000 W / m².2 Under illumination conditions, the target photovoltaic module is short-circuited and tested to obtain the short-circuit current of the target photovoltaic module. Then, based on the proportional relationships obtained from the test and the short-circuit current of the target photovoltaic module, and combined with the actual usage environment of the photovoltaic module, the maximum average forward rectified current required by the bypass device in the target photovoltaic module is determined, thereby reducing the maximum current value required by the bypass device in the photovoltaic module and reducing the manufacturing cost of the target photovoltaic module.

[0076] In one embodiment, the individual testing of the photovoltaic module under various shading conditions includes: testing the photovoltaic module individually under cloud shading conditions, simulated bird droppings shading conditions, and simulated shadow shading conditions.

[0077] This application involves conducting individual tests on photovoltaic modules under cloud cover, simulated bird droppings, and simulated shadow conditions to obtain multiple proportional relationships between the maximum average forward rectified current of the bypass device and the short-circuit current of the photovoltaic module under the corresponding shading conditions. Then, based on these proportional relationships, the short-circuit current of the target photovoltaic module, and the actual operating environment of the photovoltaic module, the required maximum average forward rectified current value for the bypass device installed in the target photovoltaic module can be determined.

[0078] This application also provides a photovoltaic module, including multiple cell groups and bypass devices connected in parallel with each of the cell groups, wherein the maximum average forward rectified current value of each bypass device is determined by the method described in any of the above embodiments.

[0079] Based on the proportional relationships obtained from the tests and the short-circuit current of the target photovoltaic module obtained from the tests, and in combination with the actual usage environment of the photovoltaic module, this application determines the value of the maximum average forward rectified current required by the bypass device in the target photovoltaic module, thereby reducing the maximum current value required by the bypass device in the photovoltaic module and reducing the manufacturing cost of the photovoltaic module.

[0080] In one embodiment, each of the battery cell groups includes multiple battery strings, and the battery cells in each battery string are connected in series with each other through a conductive material. The battery strings are connected in series and parallel to form the battery cell group.

[0081] In one embodiment, the battery cell is a half-cell, a three-cell, a four-cell, or a six-cell cell. A half-cell photovoltaic module refers to a module where a whole cell is cut in half, and the individual cells are connected in series and then in parallel, shortening the internal connection path and thus reducing losses. The principle of multi-cell modules is the same as that of half-cell modules; the battery cell is cut into multiple pieces of equal area, and then various series connections are made in parallel, which can further reduce the resistance loss within the photovoltaic module. Similarly, the principle of the bypass diode is also the same as that of the half-cell module, except that in a half-cell module, half-cell battery string 1, half-cell battery string 2, and the bypass diode are connected in parallel. Taking a four-cell photovoltaic module as an example, a four-cell photovoltaic module is formed by connecting four-cell battery strings 1, 2, 3, and 4 in parallel with the bypass diode to form 5 sets of parallel circuits. The principle of the impact on diode current is the same. If one quarter-cell cell is completely blocked, the impact on the diode's maximum operating current will be less than 1 / 4 of the Imp value. Furthermore, the distribution of quarter-cell cells is more diverse, and blocking four quarter-cell cells connected in parallel within the same circuit is even more challenging. Therefore, theoretically, the operating current of diodes in mainstream half-cell photovoltaic modules is higher than that in multi-cell modules after blocking. In other words, the diode requirements for half-cell modules should be able to cover the operating current requirements of diodes in multi-cell modules.

[0082] The most preferred photovoltaic module is a photovoltaic module composed of half cells connected in series and parallel. It is also suitable for photovoltaic modules with multiple cell arrangements, such as three-cell, four-cell, and six-cell cells.

[0083] In one embodiment, the bypass device includes a Schottky diode or a photovoltaic optimizer. Hot spot protection for photovoltaic modules is achieved by employing Schottky diodes, photovoltaic optimizers, or smart integrated devices.

[0084] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for determining the current of a bypass device in a photovoltaic module, the photovoltaic module comprising a power generation body and a bypass device connected in parallel with the power generation body, characterized in that, The method includes: The photovoltaic module is tested individually under various shading conditions to obtain multiple proportional relationships between the maximum average forward rectified current of the bypass device and the short-circuit current of the photovoltaic module. This includes: testing the photovoltaic module individually under various shading conditions to obtain multiple sets of operating current values ​​of the bypass device and the maximum power point current of the photovoltaic module; determining the corresponding short-circuit current of the photovoltaic module under various shading conditions based on the maximum power point current of the photovoltaic module obtained under various shading conditions; and determining multiple proportional relationships between the maximum average forward rectified current of the bypass device and the short-circuit current of the photovoltaic module based on the short-circuit current of the photovoltaic module under various shading conditions and the corresponding operating current values ​​of the bypass device. Based on the aforementioned proportional relationships and the short-circuit current of the target photovoltaic module obtained from the test, the maximum average forward rectified current required by the bypass device installed in the target photovoltaic module is determined; wherein, the maximum average forward rectified current of the bypass device is less than or equal to 1 times the short-circuit current of the target photovoltaic module, and greater than or equal to 0.5 times the short-circuit current of the target photovoltaic module.

2. The method for determining the current of a photovoltaic module bypass device according to claim 1, characterized in that, At an atmospheric quality of AM1.5, an ambient temperature of 25℃, and an irradiance of 1000 W / m², 2 Under illumination, the target photovoltaic module is short-circuited and then tested to obtain the short-circuit current of the target photovoltaic module.

3. The method for determining the current of a photovoltaic module bypass device according to claim 1, characterized in that, The individual testing of the photovoltaic modules under various shading conditions includes: The photovoltaic modules were tested individually under cloud cover conditions, simulated bird droppings cover conditions, and simulated shadow cover conditions.

4. A photovoltaic module, characterized in that, It includes multiple cell packs and bypass devices connected in parallel with each of the cell packs, wherein the maximum average forward rectified current value of each bypass device is determined by the current determination method of the photovoltaic module bypass device according to any one of claims 1 to 3.

5. The photovoltaic module according to claim 4, characterized in that, Each of the battery cell groups includes multiple battery strings, and the battery cells in each battery string are connected in series with each other through a conductive material. The battery strings are connected in series and parallel to form the battery cell group.

6. The photovoltaic module according to claim 5, characterized in that, The battery cell is a half-cell battery, a three-cell battery, a four-cell battery, or a six-cell battery.

7. The photovoltaic module according to claim 4, characterized in that, The bypass device includes a Schottky diode or a photovoltaic optimizer.

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