A hot spot testing method for photovoltaic strings

Abstract

The present application relates to a hot spot testing method for a photovoltaic string, which comprises the following steps: applying light intensity to the surface of the photovoltaic string; determining a photovoltaic module to be tested in the photovoltaic string; shielding the upper or lower half of the photovoltaic module to be tested, ensuring that the shielded area of ​​at least one half-cell of each corresponding cell substring is greater than 1 / 2 of the area of ​​the half-cell; measuring the temperature of the other half of the photovoltaic module to be tested to determine the half-cell of the other half; partially shielding the half-cell of the tested cell to ensure that the area of ​​the partial shielding is less than or equal to 1 / 2 of the area of ​​the half-cell of the tested cell, measuring the corresponding hot spot temperature, shielding the other half of the photovoltaic module to be tested, partially shielding the half-cell of the tested cell in the other half of the module, and measuring the corresponding hot spot temperature. The testing process is quick and effective, and the accuracy of hot spot detection of photovoltaic modules is improved.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to a hot spot testing method for photovoltaic strings. Background Art

[0002] Photovoltaic modules are composed of several solar cells. Due to factors such as shadows on the solar cells, the light on the surface of the photovoltaic module is uneven, which in turn causes hot spots on the solar cells. This may cause local burning of the photovoltaic module, melting of solder joints, and even the scrapping of the entire photovoltaic module. Therefore, it is necessary to provide a hot spot test method for photovoltaic modules.

[0003] The mainstream hot spot test method is to test based on the IEC61215 standard, determine the maximum leakage position, block at different ratios, combine the maximum power test inflection point, determine the target blocking area, select hot spots on the battery cell, block and then test the hot spot temperature, etc., but each step requires a lot of manpower and time for testing, which is a huge workload; or by taking infrared images of photovoltaic power station components, classifying them through algorithms, and calibrating special hot spot components and positions. This method is suitable for most power station applications and can effectively find the hot spot location, but this method is more about collecting and classifying existing situations, and does not measure the actual hot spot limit conditions.

[0004] At present, in the hot spot testing process of all components, it is often simply to select and choose photovoltaic cells with large leakage through complex testing methods, and conduct multiple tests to determine the shielding area. This testing process is very cumbersome and is more of a general test. It cannot conduct quick and effective testing based on the actual situation of the power station and the characteristics of mainstream half-cell components. Summary of the invention

[0005] Based on this, it is necessary to provide a hot spot testing method for photovoltaic strings to address the above technical issues.

[0006] The present application provides a hot spot test method for a photovoltaic string, wherein the photovoltaic string comprises a plurality of photovoltaic modules connected in series, each of the photovoltaic modules comprises an upper and a lower part, and the upper and lower parts each comprise a plurality of battery substrings, wherein the battery substrings are composed of a plurality of half-cell batteries connected in series, and the method comprises:

[0007] applying light intensity to the surface of the photovoltaic string;

[0008] Determining a photovoltaic component to be tested in the photovoltaic string;

[0009] The upper or lower half of the photovoltaic module to be tested is shielded to ensure that the shielded area of ​​at least one half-cell of each corresponding cell substring is greater than 1 / 2 of the area of ​​the half-cell;

[0010] Measuring the temperature of the other half of the photovoltaic module to be tested to determine the half cell to be tested in the other half of the module; partially shielding the half cell to be tested to ensure that the area of ​​the partial shielding is less than or equal to 1 / 2 of the area of ​​the half cell to be tested, and measuring the corresponding hot spot temperature;

[0011] The other half of the photovoltaic module to be tested is shielded to ensure that the shielded area of ​​at least one half-cell of each corresponding battery substring is larger than 1 / 2 of the area of ​​the half-cell; the temperature of the other half of the photovoltaic module to be tested is measured to determine the half-cell to be tested in the other half of the module; the half-cell to be tested is partially shielded to ensure that the area of ​​the partial shielding is smaller than 1 / 2 of the area of ​​the half-cell to be tested, and the corresponding hot spot temperature is measured.

[0012] In one embodiment, determining a photovoltaic component to be tested among the plurality of photovoltaic components comprises:

[0013] Based on the shielding conditions of each photovoltaic component in the photovoltaic string, a photovoltaic component to be tested is determined.

[0014] In one embodiment, determining a photovoltaic component to be tested among the plurality of photovoltaic components comprises:

[0015] Obtaining the shading probability of each photovoltaic component in the photovoltaic string;

[0016] The photovoltaic components with the shielding probability higher than the preset value are selected as the photovoltaic components to be tested.

[0017] In one embodiment, determining a photovoltaic component to be tested among the plurality of photovoltaic components comprises:

[0018] Based on the abnormality detection information of each photovoltaic component in the photovoltaic string, a photovoltaic component to be tested is determined.

[0019] In one of the embodiments, if there are multiple half-cells to be tested in the upper or lower half of the photovoltaic module to be tested, each of the half-cells to be tested is partially shielded in turn to measure the corresponding hot spot temperature.

[0020] In one of the embodiments, based on the temperature of each of the half-cell batteries to be tested, the half-cell batteries to be tested with a higher temperature are tested first.

[0021] In one of the embodiments, a thermal imager is used to measure the temperature of each half cell in the upper or lower half of the photovoltaic module to be tested.

[0022] In one of the embodiments, the area of ​​the partial shielding of the half-cell battery to be tested is preferably less than or equal to 1 / 3 of the area of ​​the half-cell battery to be tested.

[0023] In one of the embodiments, the temperature of the half-cell battery to be tested is higher than a preset value.

[0024] In one embodiment, the irradiance of the light is between 800 and 1200 W / m 2 between.

[0025] The hot spot test method of the photovoltaic string is as follows: applying light intensity to the surface of the photovoltaic string; determining the photovoltaic module to be tested in the photovoltaic string; shielding the upper or lower half of the photovoltaic module to be tested, ensuring that the shielded area of ​​at least one half-cell of each corresponding cell substring is greater than 1 / 2 of the area of ​​the half-cell; measuring the temperature of the other half of the photovoltaic module to be tested to determine the half-cell to be tested in the other half of the module; partially shielding the half-cell to be tested, ensuring that the area of ​​the partial shielding is less than or equal to 1 / 2 of the area of ​​the half-cell to be tested, and measuring the corresponding hot spot temperature; The test method comprises the following steps: shielding each component to ensure that at least one half-cell of each corresponding battery substring is shielded in an area larger than 1 / 2 of the area of ​​the half-cell; measuring the temperature of the other half of the component in the photovoltaic component to be tested to determine the half-cell of the component to be tested in the other half; partially shielding the half-cell to be tested to ensure that the area of ​​the partial shielding is smaller than 1 / 2 of the area of ​​the half-cell to be tested, and measuring the corresponding hot spot temperature. The test process is fast and effective, and the severity of the test can be considered as the extreme case after shielding, which improves the accuracy of hot spot detection of photovoltaic components, thereby ensuring the improvement of safety, reliability and stability of photovoltaic component power stations.

[0026] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0028] Figure 1 is a schematic diagram of the structure of a photovoltaic module in an embodiment;

[0029] Figure 2 is a circuit structure diagram of a photovoltaic module in an embodiment;

[0030] Figure 3is a schematic flow chart of a hot spot testing method for a photovoltaic string in an embodiment;

[0031] Figure 4 The figure is a schematic diagram of the principle of a hot spot testing method for a photovoltaic string in an embodiment. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0033] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0034] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0035] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantity limitation, and may indicate the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships, for example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0036] The present application provides a hot spot testing method for a photovoltaic string, wherein the photovoltaic string comprises a plurality of photovoltaic modules connected in series. Figure 1 A typical structural diagram of a photovoltaic module is shown in Figure 2. Figure 1 As shown, the power generation unit (cell, possibly with chamfers at the four corners) is cut in half perpendicular to the main grid direction using a welding ribbon. After the half-cells are interconnected to form a battery string, bus bars (tinned copper strips) and welding ribbons are used to connect the top, middle and bottom positions of the component to achieve the effect of current convergence. Finally, a hole is punched on the back of the middle position to lead out the middle bus bar, and a junction box with wires and connectors is installed. After the lead-out, the photovoltaic components are connected in series and parallel through the interconnection between the connectors to output energy. Figure 1 Area A in the middle is the bus bar lead-out position, which realizes energy extraction after connecting to the junction box with diodes. The main function of the diode is to protect the internal circuit when an abnormal situation occurs; area B realizes bus bar conduction and connects the battery strings corresponding to different diodes in series; C is a schematic diagram of the junction box on the back of the component.

[0037] Figure 2 The circuit structure diagram of the photovoltaic module is as follows: Figure 2As shown, this mainstream half-cell photovoltaic module consists of two parts, the upper part and the lower part, with two strings as one unit, which is a series structure; the upper part contains three units, and the lower part contains three units. The first unit in the upper part and the first unit in the lower part are mirror-image parallel structures, separated by a wire box in the middle, and the wire box contains a bypass diode; the photovoltaic module contains these three parallel structures, and these three parallel structures are connected in series again. Furthermore, the photovoltaic modules are connected in series and parallel again as units of the photovoltaic power station (mainly in series), and generally 10-30 photovoltaic modules are connected in series to form a substring of the power station circuit.

[0038] In such a photovoltaic circuit system, it is necessary to ensure that each half-cell has the same power generation capacity, the same electrical properties (such as leakage), the same welding level, the same long-term attenuation, and even the same amount of light received by each cell (light intensity). Otherwise, the barrel effect will occur because one half-cell is not as good as the other cells, so consistency in the photovoltaic system is very important. However, the battery consistency in the photovoltaic system can be sorted by testing each cell in advance, but the consistency of the environment cannot be judged in advance. There will be differences in different installation areas, and the environment will continue to change during the 20 to 30 years of photovoltaic product use, especially cloudy weather and some shade caused by trees, bird droppings, etc., which will turn the local power supply into a load and cause hot spot problems.

[0039] Although each parallel unit has a bypass diode for protection, the increasing power of the components (increasing current and voltage) will actually increase the hot spot problem. In actual applications, hot spot testing is very complicated. Normally, only a small number of components will be tested for hot spots when the product is introduced, and most components used in power stations cannot be accurately tested. However, once the hot spot problem occurs, the operating temperature of the component problem point will often be higher than 100°C, and even 150°C or higher local temperatures will occur, which will directly cause burning.

[0040] The present application provides a method for testing hot spots in a photovoltaic string. The components in the photovoltaic string include an upper and a lower part. The upper and lower parts each include a plurality of battery substrings. The battery substrings are composed of a plurality of half-cell batteries connected in series. Figure 3 As shown, the method includes:

[0041] Step 201, applying light intensity to the surface of the photovoltaic string;

[0042] Step 202, determining a photovoltaic component to be tested in the photovoltaic string;

[0043] Step 203, shielding the upper or lower half of the photovoltaic module to be tested, ensuring that the shielded area of ​​at least one half-cell of each corresponding cell substring is greater than 1 / 2 of the area of ​​the half-cell;

[0044] Step 204, measuring the temperature of the other half of the photovoltaic module to be tested to determine the half cell to be tested in the other half of the module; partially shielding the half cell to be tested to ensure that the area of ​​the partial shielding is less than or equal to 1 / 2 of the area of ​​the half cell to be tested, and measuring the corresponding hot spot temperature;

[0045] Step 205, shielding the other half of the photovoltaic module to be tested, ensuring that the shielded area of ​​at least one half-cell of each corresponding battery substring is larger than 1 / 2 of the area of ​​the half-cell; measuring the temperature of the other half of the photovoltaic module to be tested to determine the half-cell to be tested in the other half of the module; partially shielding the half-cell to be tested, ensuring that the partially shielded area is smaller than 1 / 2 of the area of ​​the half-cell to be tested, and measuring the corresponding hot spot temperature.

[0046] When the test of the photovoltaic component to be tested is completed, steps 201 to 205 are repeated to perform hot spot tests on other untested components in the photovoltaic string.

[0047] It should be noted that in step 203 of the present embodiment, either the upper half of the photovoltaic assembly to be tested or the lower half of the photovoltaic assembly to be tested can be blocked. If in step 203, the upper half of the photovoltaic assembly to be tested is blocked, then in step 205, the lower half of the photovoltaic assembly to be tested is blocked, and the upper half of the photovoltaic assembly to be tested is not blocked at this time; correspondingly, if in step 203, the lower half of the photovoltaic assembly to be tested is blocked, then in step 205, the upper half of the photovoltaic assembly to be tested is blocked, and the lower half of the photovoltaic assembly to be tested is not blocked at this time.

[0048] The following will explain the principle of the hot spot test in this application with reference to examples:

[0049] Due to the special structure of half-cell photovoltaic modules, partial obstruction often occurs in actual application, such as the shadow of the front row modules obstructing the lower half of the rear row modules (or the lawn growing too high to the south); for example, for photovoltaic modules on the roof, the buildings in front often obstruct some batteries in the lower half of the entire photovoltaic module array during a specific period of time; for example, there are protrusions above the module power station (trees or eaves, ridge protrusions, door or window positions, etc.), which will cause obstruction to the upper half of some modules in the photovoltaic power station. This obstruction is long-term and unavoidable. In this case, because the area of ​​the module in the obstructed part is large, the diode is started, and because the area of ​​the battery that becomes the load is large (that is, the area that becomes the resistor to consume energy is relatively large), there will be no obvious hot spot phenomenon.

[0050] More importantly, because the photovoltaic modules in the power station are multiple series connected, each parallel unit is a basic unit in the module string (currently the mainstream product contains three parallel units in one module). For the sake of simplicity, it is assumed that the upper part of one of the parallel units is shielded, such as Figure 4 As shown, under normal working conditions, the working current of the component string is I, the current in the upper half of the parallel unit is I1, and the current in the lower half is I2. The bypass diode is in the cut-off state and there is no current. The current values ​​of I1 and I2 are equivalent, I1+I2=I, and all parallel units perform similarly.

[0051] After shielding the upper half of one of the parallel units, the parallel unit becomes a load, and the voltage value of AB is positive. The typical voltage value is VB-VA=-0.3V (here is BA, that is, the voltage on the left is higher than the voltage on the right, and the current flows from low voltage to high voltage when used as a power supply), and the diode starts. At this time, because the other components in the component string are working normally, it can be considered that the total current I value remains unchanged (the light intensity remains unchanged), that is, I11+I12+I22=I=I1+I2 (it is worth noting that because the entire photovoltaic system has the function of maximum power output, if a large number of components are shielded by a large area, the current I in the system will become smaller. Extreme example: In an 18-piece component system, all components are shielded by a material with a light transmittance of 33%, and only one component is not shielded. In order to achieve maximum power output, the current of this system will become 33% of the original current. Similarly, because the unshielded component is in series with other components, the current of this component will also become 33%.

[0052] That is to say, when the upper part of a parallel unit is blocked, the current of I11 decreases. At this time, the characteristics of the half-cell component design appear. For the current value, I11+I12+I22=I, the current of I11 decreases (basically 0 when the upper part is completely blocked), while the current of I remains unchanged (I12+I22+I11=I), and the current of I12+I22 increases, that is, they jointly absorb the current reduced by I11.

[0053] Regarding voltage, because the voltages at points A and B are positive (under normal unobstructed conditions, the voltage of the parallel unit is VB-VA = -13.5V, which is a positive value, so B is the positive pole and the external current is output from B), the entire parallel unit also becomes a load. Although the lower half is not blocked, because the voltage value at point B is lower than that at point A, the components in the lower half also become a load.

[0054] In this case, the lower half of the parallel unit is not blocked, and theoretically it is a power structure in a normal power generation state. In this case, the lower half of the parallel unit consists of 20 half-cell batteries. When working normally, each battery operates with a current of I2 and a voltage of 0.675V (B to A direction), and the total voltage is 13.5V. But after the upper half of the components are blocked, the voltage of the lower half becomes a typical value of -0.3V. At this time, according to experiments, when one of the lower half-cell batteries is blocked (for example, only a small part is blocked), the battery will have a negative pressure. In this case, its load voltage is about 0.675×(20-1)+0.3, which is the sum of the working voltages of the other batteries, plus the voltage difference between A and B.

[0055] Therefore, in this case, the hot spot effect produced by the battery cell with the lower part blocked is much greater than that of the battery cell with a large area blocked above (the area that becomes the load after the upper part is blocked is large, and the energy consumption per unit area is small). This type of blocking method can be considered to be more stringent than the conventional hot spot test.

[0056] Based on the above test principles, this application provides a method for hot spot detection of outdoor photovoltaic modules that are already in use, targeting the current mainstream half-cell photovoltaic modules. By shielding the upper / lower half modules, the mutual influence of parallel units in the module is reduced, and the test is simpler and faster. At the same time, it is indeed common that the upper / lower half of the module is blocked by a large area, and the other half has a small area of ​​​​blocking or poor conditions (such as bird droppings, local dirt, and poor battery itself). Finally, the severity of the test can be considered as the extreme case after shielding, which improves the accuracy of hot spot detection of photovoltaic modules, thereby ensuring the improvement of safety, reliability and stability of photovoltaic module power stations.

[0057] In one embodiment, determining the photovoltaic component to be tested among the plurality of photovoltaic components includes: determining the photovoltaic component to be tested based on the shading condition of each photovoltaic component in the photovoltaic string. Specifically, obtaining the shading probability of each photovoltaic component in the photovoltaic string; selecting the photovoltaic component with the shading probability higher than a preset value as the photovoltaic component to be tested. That is, testing photovoltaic components with a high shading probability in an actual application environment, such as shadow shading, etc.

[0058] In one of the embodiments, determining the photovoltaic component to be tested among the plurality of photovoltaic components includes: determining the photovoltaic component to be tested based on abnormality detection information of each of the photovoltaic components in the photovoltaic string.

[0059] This application is aimed at photovoltaic power stations that are actually in operation. In order to save time and energy, hot spot testing can be performed on only specific one or several components, such as components with more shading, abnormal components during normal inspections, etc. It is not necessary to perform hot spot testing on all components in the system power station.

[0060] In one of the embodiments, if there are multiple half-cells to be tested in the upper or lower half of the photovoltaic module to be tested, each of the half-cells to be tested is partially shielded in turn to measure the corresponding hot spot temperature.

[0061] Specifically, the specific method for the present application to determine the half-cell battery to be tested in the upper / lower half assembly of the photovoltaic module is: according to the temperature of each half-cell battery in the upper / lower half assembly of the photovoltaic module to be tested, select the battery cell with a higher temperature as the half-cell battery to be tested in the upper / lower half assembly. Furthermore, the temperature of the half-cell battery to be tested should be higher than the preset value. The present application selects battery cells with higher temperatures for testing, generally 1-3 half-cell batteries are sufficient, and in principle no more than 3 cells. Testing more battery cells will increase the workload. For example, if 3 battery cells with higher temperatures are selected, the test steps need to be performed one by one, that is, the second battery cell is tested after the first battery cell is tested, and so on. Based on the temperature of each half-cell battery to be tested, the present application gives priority to testing the half-cell battery to be tested with a higher temperature.

[0062] The temperature of each half cell in the upper or lower half of the photovoltaic module to be tested is measured and observed by using a thermal imager.

[0063] In one of the embodiments, the area of ​​the partial shielding of the half-cell battery to be tested is preferably less than or equal to 1 / 3 of the area of ​​the half-cell battery to be tested.

[0064] Specifically, when partially shielding a battery cell with a higher temperature to measure the hot spot temperature of the battery cell, the area of ​​the partial shielding is ≤ 1 / 2 of the total area of ​​the half-cell battery. Preferably, the area of ​​the partial shielding is ≤ 1 / 3 of the total area of ​​the half-cell battery.

[0065] In one embodiment, the irradiance of the light is between 800 and 1200 W / m 2 between.

[0066] The hot spot test method for photovoltaic strings provided in the embodiment of the present application can be combined with the IEC test steps in indoor testing. During the IEC test process, the upper / lower half of the component is shielded and tested to compare the differences in test results. Indoor IEC testing can also be performed on photovoltaic components that have uncertainties after testing.

[0067] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0068] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for testing hot spots of a photovoltaic string, wherein the photovoltaic string comprises a plurality of photovoltaic modules connected in series, each of the photovoltaic modules comprises an upper and a lower part, the upper and lower parts each comprising a plurality of battery substrings, the battery substrings comprising a plurality of half-cell batteries connected in series, characterized in that: The method comprises: applying light intensity to the surface of the photovoltaic string; Determining a photovoltaic component to be tested in the photovoltaic string; The upper or lower half of the photovoltaic module to be tested is shielded to ensure that the shielded area of ​​at least one half-cell of each corresponding cell substring is greater than 1 / 2 of the area of ​​the half-cell; Measuring the temperature of the other half of the photovoltaic module to be tested to determine the half cell to be tested in the other half of the module; partially shielding the half cell to be tested to ensure that the area of ​​the partial shielding is less than or equal to 1 / 2 of the area of ​​the half cell to be tested, and measuring the corresponding hot spot temperature; The other half of the photovoltaic module to be tested is shielded to ensure that the shielded area of ​​at least one half-cell of each corresponding battery substring is larger than 1 / 2 of the area of ​​the half-cell; the temperature of the other half of the photovoltaic module to be tested is measured to determine the half-cell to be tested in the other half of the module; the half-cell to be tested is partially shielded to ensure that the area of ​​the partial shielding is smaller than 1 / 2 of the area of ​​the half-cell to be tested, and the corresponding hot spot temperature is measured.

2. The method according to claim 1, characterized in that Determining a photovoltaic component to be tested among the plurality of photovoltaic components comprises: Based on the shielding conditions of each photovoltaic component in the photovoltaic string, a photovoltaic component to be tested is determined.

3. The method according to claim 2, characterized in that Determining a photovoltaic component to be tested among the plurality of photovoltaic components comprises: Obtaining the shading probability of each photovoltaic component in the photovoltaic string; The photovoltaic components with the shielding probability higher than the preset value are selected as the photovoltaic components to be tested.

4. The method according to claim 1, characterized in that Determining a photovoltaic component to be tested among the plurality of photovoltaic components comprises: Based on the abnormality detection information of each photovoltaic component in the photovoltaic string, a photovoltaic component to be tested is determined.

5. The method according to claim 1, characterized in that If there are multiple half-cells to be tested in the upper or lower half of the photovoltaic module to be tested, each of the half-cells to be tested is partially shielded in turn to measure the corresponding hot spot temperature.

6. The method according to claim 5, characterized in that Based on the temperature of each of the half-cell batteries to be tested, the half-cell battery to be tested with a higher temperature is tested first.

7. The method according to claim 1, characterized in that Use a thermal imager to measure the temperature of each half cell in the upper or lower half of the photovoltaic module to be tested.

8. The method according to claim 1, characterized in that The area of ​​the partial shielding of the half-cell battery to be tested is less than or equal to 1 / 3 of the area of ​​the half-cell battery to be tested.

9. The method according to claim 1, characterized in that: The temperature of the half-cell battery to be tested is higher than a preset value.

10. The method according to claim 1, characterized in that The irradiance of the light intensity is between 800 and 1200 W / m 2 between.

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