Test method and test system for battery piece

Abstract

The application provides a battery piece testing method and testing system, and relates to the photovoltaic technical field. The testing method comprises the following steps: obtaining a first photoluminescence intensity value of a to-be-tested battery piece under a preset standard sunlight intensity; the to-be-tested battery piece comprises a substrate; the preset standard sunlight intensity is less than or equal to one standard sunlight intensity; based on the first photoluminescence intensity value, a linear regression method is used to calculate a first collection loss current density lost by the to-be-tested battery piece due to the substrate collection. In the first aspect, the whole testing process is a non-contact type, the probe is not used basically, the risk of short circuit is not caused, the difficulty that the probe and the testing point of the battery piece need to be accurately aligned is avoided, the application range is wide, and the application is still suitable for battery pieces without main grids; in the second aspect, testing errors caused by poor contact of the probe are not brought in; and in the third aspect, the testing time is greatly shortened, the testing efficiency is high, and the accuracy is very high.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology, and in particular to a testing method and system for solar cells. Background Technology

[0002] Accurately testing the various electrical parameters of solar cells is the basis for evaluating their performance and classifying them.

[0003] Among them, the current density lost by the solar cell due to substrate collection is of great reference value for evaluating the performance of the solar cell and classifying the solar cell.

[0004] However, currently, the measurement of the current density loss due to substrate collection in solar cells is not accurate enough, resulting in large errors in the electrical test parameters of solar cells. Summary of the Invention

[0005] This invention provides a testing method and system for solar cells, aiming to improve the testing accuracy of the collection loss current density of solar cells due to substrate collection.

[0006] A first aspect of the present invention provides a method for testing battery cells, comprising:

[0007] Obtain the first photoluminescence intensity value of the solar cell under test under a preset number of standard solar intensities; the solar cell under test includes: a substrate; the preset number of standard solar intensities is less than or equal to 1 standard solar intensity;

[0008] Based on the first photoluminescence intensity value, the first collection loss current density of the battery cell under test due to collection by the substrate is calculated by linear regression.

[0009] In this application, for the battery cell under test, the first photoluminescence intensity value can be obtained by non-contact measurement. Then, based solely on the first photoluminescence intensity value, the first collection loss current density lost by the battery cell under test due to substrate collection can be calculated by linear regression. First, the entire testing process for the first collection loss current density of the solar cell under test due to substrate collection is non-contact. Since probes are largely not used, the risk of short circuits caused by misalignment of positive and negative terminals due to overly dense probes is avoided, as is the difficulty of precise alignment between the probes and the test points on the solar cell. Therefore, the solar cell testing method provided in this application is applicable to various types of solar cells, with a wide range of applications, even for solar cells without a main grid. Second, since probes are largely not used, test errors due to poor probe contact are avoided. Third, only the first photoluminescence intensity value of the solar cell under test needs to be obtained and used for calculation. Fewer parameters are required for testing the solar cell under test, thus greatly shortening the testing time and increasing testing efficiency. Fourth, the first photoluminescence intensity value of the solar cell under test has a high linear correlation with the first collection loss current density. The first collection loss current density calculated using linear regression of this first photoluminescence intensity value has high accuracy.

[0010] A second aspect of the present invention provides a testing system for solar cells, comprising:

[0011] The first photoluminescence intensity value acquisition module is used to acquire the first photoluminescence intensity value of the battery cell under test under a preset number of standard solar irradiances; the battery cell under test includes: a substrate; the preset number of standard solar irradiances is less than or equal to 1 standard solar irradiance.

[0012] The calculation module is used to calculate the first collection loss current density of the battery cell under test due to collection by the substrate using a linear regression method based on the first photoluminescence intensity value.

[0013] The above-mentioned testing methods and systems for solar cells have the same or similar beneficial effects, and will not be repeated here to avoid duplication. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 A flowchart illustrating the steps of a first-type battery cell testing method in an embodiment of the present invention is shown;

[0016] Figure 2 A flowchart illustrating the steps of a second battery cell testing method in an embodiment of the present invention is shown;

[0017] Figure 3 A flowchart illustrating the steps of a third battery cell testing method in an embodiment of the present invention is shown;

[0018] Figure 4 A schematic diagram showing the fitting curve of the second photoluminescence intensity value of the sampled battery cell in an embodiment of the present invention and the collection loss current density lost by the substrate is shown.

[0019] Figure 5 A schematic diagram showing the comparison between the measured short-circuit current density and the calculated short-circuit current density of the sampled battery cells in an embodiment of the present invention is shown. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] This invention provides a testing method for battery cells, referring to... Figure 1 The testing method for this solar cell may include the following steps.

[0022] Step 101: Obtain the first photoluminescence intensity value of the battery cell under test under a preset number of standard solar intensities; the battery cell under test includes: a substrate; the preset number of standard solar intensities is less than or equal to 1 standard solar intensity.

[0023] The solar cell under test mentioned in this application can be a solar cell with electrodes on both sides, a back-contact solar cell, a solar cell with a main grid, or a solar cell without a main grid, etc., and there are no specific limitations on the structure of the solar cell under test. The solar cell under test can be a whole solar cell or a segmented solar cell, and there are no limitations on the size of the solar cell under test. It should be noted that for solar cells without a main grid, the small metal contact area can cause short circuits in the press-fit contact method used in related technologies, which cannot guarantee the accuracy of the test.

[0024] This application allows for the acquisition of the first photoluminescence intensity value of a tested solar cell under a preset number of standard solar intensities using photoluminescence instruments. The acquisition of this first photoluminescence intensity value can be achieved through non-contact measurement. The preset number of standard solar intensities is greater than 0 and less than or equal to 1 standard solar intensity. The specific magnitude of this preset number of standard solar intensities is related to the type of solar cell. The magnitude of 1 standard solar intensity is not limited; for example, 1 standard solar intensity is 1000 W / m². 2 .

[0025] A solar cell includes a substrate, which provides support for the various functional layers within the cell and performs functions such as light absorption, electrical conductivity, and current collection. The type of substrate is not limited here. For example, the substrate can be a silicon substrate, and the doping type is also not limited; it can have N-type or P-type doping. The crystal type of the substrate is also not limited; for example, the crystal type can be single crystal, microcrystalline, amorphous, polycrystalline, etc.

[0026] Step 102: Based on the first photoluminescence intensity value, calculate the first collection loss current density of the battery cell under test due to collection by the substrate using linear regression.

[0027] The first collection loss current density of a solar cell due to substrate collection is typically related to substrate losses, surface state conduction, and surface minority carrier recombination. These factors can cause partial or complete current loss during transmission, thus reducing the cell's performance. For example, when the substrate of the solar cell under test is silicon, the first collection loss current density refers to the proportion of long-wavelength (low-energy) photons under low light intensity. However, silicon-based materials have weak absorption of long-wavelength photons, which may result in some photons being lost without being absorbed. Therefore, the first collection loss current density is greatly affected by the recombination of excess carriers, and its actual variation can be significant, impacting the accuracy of the solar cell's electrical parameter testing.

[0028] The inventors discovered through research that, for different battery types, when the battery cells are tested using non-contact testing methods, there is a linear relationship between the first photoluminescence intensity value under a preset standard sunlight intensity and the first collection loss current density lost by the substrate. A linear regression analysis method can be used to establish a linear relationship model between this first photoluminescence intensity value under the preset standard sunlight intensity and the first collection loss current density lost by the substrate, thus accurately obtaining the first collection loss current density through the first photoluminescence intensity value. The specific magnitude of the preset standard sunlight intensity is related to the battery type, and different battery types may correspond to different preset standard sunlight intensities. Photoluminescence value refers to the parameter of the light intensity produced by the battery cell under light excitation; the photoluminescence value obtained under different light intensities also varies.

[0029] In this application, for the battery cell under test, the first photoluminescence intensity value can be obtained by non-contact measurement. Then, based solely on the first photoluminescence intensity value, the first collection loss current density lost by the battery cell under test due to substrate collection can be calculated by linear regression. First, the entire testing process for the first collection loss current density of the solar cell under test due to substrate collection is non-contact. Since probes are largely not used, the risk of short circuits caused by misalignment of positive and negative terminals due to overly dense probes is avoided, as is the difficulty of precise alignment between the probes and the test points on the solar cell. Therefore, the solar cell testing method provided in this application is applicable to various types of solar cells, with a wide range of applications, even for solar cells without a main grid. Second, since probes are largely not used, test errors due to poor probe contact are avoided. Third, only the first photoluminescence intensity value of the solar cell under test needs to be obtained and used for calculation. Fewer parameters are required for testing the solar cell under test, thus greatly shortening the testing time and increasing testing efficiency. Fourth, the first photoluminescence intensity value of the solar cell under test has a high linear correlation with the first collection loss current density. The first collection loss current density calculated using linear regression of this first photoluminescence intensity value has high accuracy.

[0030] In some embodiments, the battery test cell testing method further includes step 103 in addition to step 102. Step 103 involves determining the electrical parameters of the battery cell under test based on the first collection loss current density lost by the battery cell under test due to collection by the substrate; the electrical parameters include at least one of short-circuit current density, short-circuit current, and photoelectric conversion efficiency.

[0031] Specifically, related technologies typically employ contact-based measurements for short-circuit current density and short-circuit current testing of solar cells. However, in contact-based testing, good contact current collection is achieved primarily through the pressing of conductive materials such as probes against the solar cell. This results in pressure applied to the solar cell by the test fixture, which has a certain probability of damaging the electrodes or even the passivation layer of the solar cell by the probes, affecting the actual efficiency of the solar cell. Using a small number of probe arrays for testing can lead to a significant increase in external resistance due to excessive transmission distance, affecting short-circuit current density and other test results. For back-contact solar cells, using overly dense probe arrays can also lead to misalignment of positive and negative terminals, causing short circuits. Furthermore, contact-based testing is susceptible to testing errors due to poor probe contact. Therefore, existing contact-based testing methods have certain limitations. In addition, contact-based testing is often difficult to implement for solar cells with no or few main busbars.

[0032] To address the aforementioned technical issues, this application considers that the first collection loss current density lost by the solar cell due to substrate collection is typically closely related to the solar cell's short-circuit current density, short-circuit current, and photoelectric conversion efficiency. Therefore, by obtaining the first collection loss current density lost by the solar cell under test due to substrate collection, the short-circuit current density, short-circuit current, and photoelectric conversion efficiency of the solar cell under test can be determined. Since probes are largely not used, the risk of short circuits caused by misalignment of positive and negative terminals due to overly dense probes is avoided, as is the difficulty of precisely aligning the probes with the test points on the solar cell. Therefore, the solar cell testing method provided in this application is applicable to various types of solar cells, with a wide range of applications, even for solar cells without a main grid. Furthermore, since probes are largely not used, test errors caused by poor probe contact are avoided. Additionally, the high accuracy of the first collection loss current density test due to substrate collection ensures accurate subsequent testing of electrical parameters such as short-circuit current density, short-circuit current, and photoelectric conversion efficiency.

[0033] When the first collection loss current density lost by the cell under test due to substrate collection is obtained, the non-contact determination method for the short-circuit current density is not limited. For example, the short-circuit current density of the cell under test can be obtained by subtracting the loss current density of the cell under test from the lossless current density Jideal. The loss current density of the cell under test includes: the aforementioned first collection loss current density JLoss lost by the cell under test due to substrate collection. base The reflection loss current density JLoss due to reflection R The loss of front membrane absorption current density JLoss due to light absorption by the front membrane front The transmission loss current density JLoss due to the light lost through the solar cell. TThe lossless current density Jideal of the solar cell under test can be the lossless current density Jideal when the external quantum efficiency EQE is 1, or the lossless current density achievable by the solar cell across the entire wavelength range without considering all losses. Since solar cells typically absorb light in the wavelength range of 300nm-1200nm, the lossless current density Jideal when the external quantum efficiency EQE is 1 can also be the ideal current density achievable by the solar cell in the 300nm-1200nm range without considering all losses. If the solar cell under test also includes a front metal electrode located on the side of the front film facing away from the substrate, the loss current density of the solar cell under test can further include the metal blocking loss current density Jlossmetal caused by the light blocked by the front metal electrode. The cell under test also includes a back film located on the backlight side of the substrate. If at least one of the aforementioned front film, back film and substrate includes a heavily doped portion, the loss current density of the cell under test may also include the parasitic absorption loss current density lost due to parasitic absorption by the heavily doped portion.

[0034] In this application, the lossless current density Jideal of the solar cell under test is typically a design parameter of the cell and can be obtained from its design parameters. For example, the value of the lossless current density Jideal can be 46.3 mA / cm². 2 (mA per square centimeter) -46.5mA / cm 2 The reflection loss current density JLoss of the tested solar cell due to reflection. R This mainly refers to the current density lost due to light reflected from the surface of the solar cell that is not absorbed by the cell. The current density lost due to light absorbed by the front film (JLoss) is also included. frontThis mainly refers to the current density lost due to light absorption by the front film but not by the silicon substrate. During normal operation of the solar cell, the side of the substrate that primarily absorbs light is the light-facing side, while the back-light side is opposite to the light-facing side. The front film located on the light-facing side of the substrate refers to all film layers in the solar cell located on the light-facing side of the substrate, excluding the front metal electrode located on the light-facing side. For example, the front film may include a front passivation layer, etc. The specific film layers included in the front film are not limited. The back film located on the back-light side of the silicon substrate refers to all film layers in the solar cell located on the back-light side of the substrate, excluding the back metal electrode located on the back-light side. For example, the back film may include a back passivation layer, etc. The specific film layers included in the back film are not limited. The metal blocking loss current density Jlossmetal, which is lost due to light blocked by the front metal electrode, is one of the design parameters of the solar cell and can be obtained from the design parameters of the solar cell. For example, when testing a solar cell with electrodes on both sides (such as a TOPCon cell), the metal shading loss current density Jlossmetal can be obtained as follows: Jlossmetal = Jideal × Shading Ratio, where the shading ratio is the proportion of the area of ​​the metal shading on the light-facing side to the total area of ​​the light-facing side. Therefore, for solar cells including the front metal electrode, the metal shading loss current density can also be obtained non-contactly. The doping concentration of the aforementioned heavily doped portion can be greater than or equal to 1E18 atoms / cm². 3 This can be because only the front film includes the heavily doped portion, or only the rear film includes the heavily doped portion, or only the substrate includes the heavily doped portion, or both the front and rear films include the heavily doped portion, or both the front and substrate include the heavily doped portion, or both the substrate and the rear film include the heavily doped portion, or both the front, rear, and substrates include the heavily doped portion.

[0035] The lossless current density (Jideal) and various loss current densities of the solar cell under test can be obtained non-contactly. Therefore, this application can at least achieve non-contact determination of the short-circuit current density of the solar cell under test. Given the short-circuit current density, the short-circuit current and photoelectric conversion efficiency of the solar cell under test can be obtained solely through non-contact methods such as calculation. Furthermore, since the first collection loss current density of the solar cell under test provided by this application is more accurate due to substrate collection, the accuracy of the obtained short-circuit current density, short-circuit current, and photoelectric conversion efficiency of the solar cell under test can be further improved.

[0036] In this application, the short-circuit current is the current flowing through the solar cell when the voltage across the cell is zero (i.e., when the cell is short-circuited), usually denoted as Isc, and it is also the maximum current that can be drawn from the solar cell. The short-circuit current density refers to the amount of current flowing through a unit area of ​​the solar cell when it is in a short-circuit state, and its unit is mA / cm². 2 As mentioned earlier, the short-circuit current density of a solar cell can be calculated by subtracting the cell's loss current density from the loss current density (Jideal). Short-circuit current and short-circuit current density can affect the final efficiency and test rating of the solar cell.

[0037] This invention provides another method for testing battery cells, referring to... Figure 2 The testing method for this solar cell may include the following steps.

[0038] Step 201: For the battery type corresponding to the battery cell under test, within a range of less than or equal to 1 standard solar intensity, determine the preset number of standard solar intensities corresponding to the second photoluminescence intensity value that has the highest linear correlation with the collection loss current density lost due to substrate collection for the battery type.

[0039] The type of battery corresponding to the cell under test is related to its structure. The type of battery corresponding to the cell under test can refer to the type of battery corresponding to the structure of the cell under test. For example, the type of cell under test can be a TOPCON (tunneling oxide passivated contact) cell, a BC (back contact) cell, etc.

[0040] For various battery types, the applicant discovered that, within a certain range of standard solar intensities less than or equal to one standard solar intensity, the photoluminescence intensity value of each battery type exhibits an approximately linear correlation with the collection loss current density lost due to substrate collection. The next step involves identifying, within a range of standard solar intensities less than or equal to one standard solar intensity, the standard solar intensity at which the photoluminescence intensity value of the battery type shows the highest linear correlation with the collection loss current density lost due to substrate collection. This standard solar intensity with the highest linear correlation is then the preset standard solar intensities for the battery under test. The strength of this linear correlation can be determined by the correlation coefficient and the goodness of fit of the linear regression model (R²). 2Characterization is performed using methods such as [list of methods]. In this step, for the battery type corresponding to the cell under test, within a range of less than or equal to one standard solar intensity, the aforementioned preset standard solar intensity corresponding to the second photoluminescence intensity value with the highest linear correlation to the collection loss current density lost due to substrate collection for that battery type is identified. It is understood that the preset standard solar intensity is related to the battery type, and the preset standard solar intensity may differ for different battery types.

[0041] In some embodiments, prior to step 201, the method may further include steps S1 and S2. Step 201 may include step 2011. Step S1: For multiple sampled cells of various efficiencies corresponding to the battery type of the cell under test, determine the second collection loss current density lost by each sampled cell due to substrate collection. Step S2: For each sampled cell of various efficiencies corresponding to the battery type of the cell under test, measure multiple second photoluminescence intensity values ​​for each sampled cell from an initial standard solar intensity up to one standard solar intensity. The initial standard solar intensity is greater than 0 and less than or equal to 0.005 standard solar intensities. Step 2011: For multiple sampled cells of various efficiencies corresponding to the battery type of the cell under test, determine from the multiple second photoluminescence intensity values ​​of the sampled cells the same preset number of standard solar intensities that have the highest linear correlation with the second photoluminescence intensity lost by each sampled cell due to substrate collection.

[0042] Specifically, the battery type corresponding to the tested solar cell typically contains multiple efficiency levels, which refer to photoelectric conversion efficiency. For solar cells of a certain battery type with different efficiency levels, the applicant discovered that, within a range of less than or equal to one standard solar intensity, or within the range from the initial standard solar intensity to one standard solar intensity, under the same preset standard solar intensity, the photoluminescence intensity values ​​of solar cells at each efficiency level all exhibit an approximately linear correlation with the collection loss current density lost due to substrate collection for that battery type. Steps S1, S2, and 2011 here involve identifying, within the range of an initial standard solar intensity to one standard solar intensity, multiple sampled cells of various efficiencies corresponding to the battery type under test. The specific standard solar intensity corresponding to the second photoluminescence intensity value that exhibits the highest linear correlation with the collection loss current density lost due to substrate collection in each sampled cell of that battery type is determined. This ensures that the same preset standard solar intensity is applicable to all cells of the battery type corresponding to the cell under test, enabling non-contact testing of all cells in that battery type and improving testing accuracy. For example, the initial standard solar intensity could be 0.001, 0.002, 0.003, 0.004, or 0.005 standard solar intensities. The sampled solar cells here cover multiple efficiency levels of this type of solar cell, ensuring comprehensive sampling and guaranteeing that the preset standard light intensity is applicable to solar cells of the same type but different efficiencies, further improving test accuracy.

[0043] The second photoluminescence intensity value that has the highest linear correlation with the collection loss current density lost due to substrate collection in each sampled cell of the battery type is defined as follows: For all sampled cells of each efficiency level within the battery type corresponding to the tested cell, the second photoluminescence intensity value under the same preset standard solar energy intensity shows the highest linear correlation with the collection loss current density lost due to substrate collection in the corresponding sampled cell. Alternatively, it can refer to the majority of sampled cells of each efficiency level within the battery type corresponding to the tested cell, where the second photoluminescence intensity value under the same preset standard solar energy intensity shows the highest linear correlation with the collection loss current density lost due to substrate collection in the corresponding sampled cell. Here, "majority" means more than half of the total number of sampled cells of each efficiency level within the battery type corresponding to the tested cell.

[0044] There is no limitation on whether the intensity step value between adjacent standard solar intensities is equal. The goal is to measure the change in photoluminescence intensity of each sampled cell at each efficiency level within the battery type corresponding to the tested cell, while also considering the computational complexity. For example, the intensity step value between adjacent standard solar intensities can be an equal step value, such as 0.002 standard solar intensities, and there is no specific limitation on its magnitude.

[0045] In some embodiments, step S2 may include: for each sampled battery cell of each efficiency level within the battery type corresponding to the battery cell under test, measuring at least 15 second photoluminescence intensity values ​​for each sampled battery cell at at least 15 different standard solar intensities, starting from the aforementioned initial standard solar intensity up to one standard solar intensity. That is, if at least 15 different standard solar intensities are selected from the aforementioned initial standard solar intensity up to one standard solar intensity, then for the same sampled battery cell, at least 15 second photoluminescence intensity values ​​will be obtained at at least 15 different standard solar intensities from the aforementioned initial standard solar intensity up to one standard solar intensity. This improves the accuracy of the preset number of standard solar intensities corresponding to the battery type of the battery cell under test, as well as the accuracy of the linear regression equation, further enhancing the test accuracy.

[0046] For example, starting from the aforementioned initial standard solar intensity, multiple second photoluminescence intensity values ​​were measured for each of the sampled solar cells at 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, and 25 different standard solar intensities.

[0047] It should be noted that for multiple sampled cells of different efficiencies corresponding to the battery type under test, it is also necessary to ensure that the second photoluminescence intensity value, EL (electroluminescence intensity value), and appearance of each sampled cell are all normal, and that the short-circuit current test results of each sampled cell are relatively stable.

[0048] It should be noted that in this application, the second photoluminescence intensity value for the battery type corresponding to the battery cell under test can be referred to here, and will not be repeated here in order to avoid repetition.

[0049] In some embodiments, in step S1, the sampled cells for the battery type corresponding to the cell under test cover at least three efficiency levels. These at least three efficiency levels include: a first efficiency level that accounts for more than 50% of the total number of cells in the battery type corresponding to the cell under test; a second efficiency level higher than the first efficiency level; and a third efficiency level lower than the first efficiency level. The first efficiency level, accounting for more than 50% of the total number, means the dominant efficiency level. For a battery type, this is typically the average efficiency level, or the efficiency level immediately adjacent to it, because the number of cells with the average efficiency level or the efficiency level immediately adjacent to it is relatively large, easily exceeding 50%. Therefore, the first efficiency level can be the average efficiency level or the efficiency level immediately adjacent to it in the battery type corresponding to the cell under test. The second efficiency level can be a higher efficiency level in the battery type corresponding to the cell under test that is higher than the average efficiency level. The third efficiency level can be a lower efficiency level in the battery type corresponding to the cell under test that is lower than the average efficiency level. The differences between the second and first efficiency levels, and between the first and third efficiency levels, are all less than or equal to 0.4%. This means that while there are efficiency differences among the three levels, the differences between adjacent efficiency levels are relatively small. Smaller differences between adjacent efficiency levels indicate smaller performance differences between the sampled solar cells, facilitating the rapid identification of the same preset standard solar intensity for all sampled solar cells of the aforementioned battery type. The sampled solar cells here cover high, medium, and low efficiency levels for this battery type, ensuring comprehensive sampling and further improving test accuracy.

[0050] For example, the difference between the efficiency of the second gear and the efficiency of the first gear can be: 0.4%, 0.35%, 0.33%, 0.3%, 0.28%, 0.26%, 0.25%, 0.24%, 0.2%, and the difference between the efficiency of the first gear and the efficiency of the third gear can be: 0.4%, 0.35%, 0.32%, 0.3%, 0.29%, 0.27%, 0.25%, 0.22%, 0.2%. The difference between the efficiency of the second gear and the efficiency of the first gear can be equal to or unequal to the difference between the efficiency of the first gear and the efficiency of the third gear; there is no limitation on this. In some embodiments, the difference between the second-level efficiency and the first-level efficiency can be equal to the difference between the first-level efficiency and the third-level efficiency. Specifically, the difference can be selected as 0.2%. If a battery has an average efficiency of 28%, then batteries with efficiency higher than the average level can be selected as 28.2%, and batteries with efficiency lower than the average level can be selected as 27.8%.

[0051] It should be noted that the "at least three efficiency levels" mentioned here, in addition to the first, second, and third efficiency levels mentioned above, do not include other efficiency levels. Specifically, the second efficiency level may be further divided into multiple levels, such as an average efficiency of 28%, and also options for cells with lower efficiencies like 27.8% or 27.9%.

[0052] It should be noted that in this application, for the battery type corresponding to the battery cell under test, the sampled battery cells cover at least three efficiency levels. The sampled battery cells can be referred to here, and will not be repeated here to avoid repetition.

[0053] Step 202: Obtain the first photoluminescence intensity value of the battery cell under test under a preset number of standard solar intensities; the battery cell under test includes: a substrate; the preset number of standard solar intensities is less than or equal to 1 standard solar intensity.

[0054] This step can be referred to as step 101 above. To avoid repetition, it will not be repeated here.

[0055] Step 203: For the battery type corresponding to the battery cell under test, determine the linear regression equation between the photoluminescence intensity value under a preset number of standard solar intensities and the collection loss current density lost by the battery type due to substrate collection. The linear regression equation can be determined using the least squares method, minimizing absolute error, weighted least squares method, or by using certain statistical software or data analysis tools; there is no limitation on this. It is understood that the linear regression equation here is based on the linear relationship between the photoluminescence intensity value under a preset number of standard solar intensities and the collection loss current density lost by the battery type due to substrate collection. Therefore, a linear regression analysis method can be used to establish the linear regression equation between the photoluminescence intensity value under a preset number of standard solar intensities and the collection loss current density of the battery type. The core of the linear regression equation is to find an optimal fitting line that can predict the relationship between two variables. In some embodiments, before step 203, the method may further include: step S3, where step 203 may include step 2031. Step S3: For multiple sampled cells of various efficiencies corresponding to the battery type under test, determine the second collection loss current density lost by each sampled cell due to substrate collection. Step 2031: For multiple sampled cells of various efficiencies corresponding to the battery type under test, determine the linear regression equation between the second photoluminescence intensity value of each sampled cell under a preset number of standard solar intensities and the collection loss current density lost by the battery type due to substrate collection.

[0056] In steps S1 and S3 above, the acquisition of the second collection loss current density lost due to substrate collection for each sampled solar cell can be obtained by contact or non-contact methods, without limitation. The number of sampled solar cells corresponds to the number of second collection loss current densities lost due to substrate collection. Each sampled solar cell corresponds to a second photoluminescence intensity value under a preset number of standard solar intensities. Therefore, the number of sampled solar cells corresponds to the number of preset number of second photoluminescence intensity values ​​under standard solar intensities. Thus, for each sampled solar cell, there is a pair of values ​​for the second photoluminescence intensity value under a preset number of standard solar intensities and the second collection loss current density lost due to substrate collection. The number of sampled solar cells corresponds to the number of such pairs. Step 2031 uses the second photoluminescence intensity value under these preset standard sunlight intensities and the value of the second collection loss current density lost due to substrate collection to determine the linear regression equation of the second photoluminescence intensity value and the collection loss current density lost due to substrate collection for this type of battery. The resulting linear regression equation is applicable to all cells of this type and has broad applicability.

[0057] In some embodiments, before obtaining the second collection loss current density lost by each sampled cell due to substrate collection in steps S1 and S3, the method may further include steps S4 and S5, and steps S1 and S3 may include step S11. Step S4: For multiple sampled cells of various efficiencies corresponding to the cell under test, obtain the substrate absorption rate to wavelength and the actual current density of each sampled cell at the actual external quantum efficiency for each sampled cell; Step S5: Obtain the lossless current density of the cell type corresponding to the cell under test at the ideal external quantum efficiency. Step S11: For each sampled cell of various efficiencies corresponding to the cell under test, based on the substrate absorption rate to wavelength, the lossless current density, and the actual current density of the sampled cell at the actual external quantum efficiency, determine the second collection loss current density lost by the sampled cell due to substrate collection.

[0058] Specifically, external quantum efficiency (EQE) represents the efficiency of a solar cell in converting incident photons into output electrons. EQE comprehensively considers photon reflection, transmission, and absorption losses, directly reflecting the energy conversion capability of the solar cell under actual illumination. Ideal EQE refers to the maximum efficiency of the solar cell in converting incident photons into output electrons under theoretically limiting conditions, assuming no losses. The substrate absorptivity (Abb) of the sampled solar cell is represented as a correction factor for the aforementioned lossless current density (Jideal) under ideal EQE. The substrate absorptivity (Abb) of the sampled solar cell can be obtained through non-contact measurement combined with simulation calculations. Specifically, the absorptivity (Abb) can be calculated from the transmittance and actual absorptivity. As mentioned earlier, the lossless current density (Jideal) is usually a design parameter of the sampled solar cell and can be obtained from its design parameters. Actual external quantum efficiency refers to the actual efficiency of the solar cell in converting incident photons into output electrons, measured under actual operating conditions, and includes all possible loss factors in the solar cell. The actual current density J of the sampled solar cell at the actual external quantum efficiency 实际EQE The QE (quantum efficiency) can be measured using a non-contact testing instrument, and the resulting sampled cell's second collection loss current density J due to substrate collection is obtained. 第二收集损失电流密度 Relatively accurate.

[0059] In some embodiments, step S11 may include: for each sampled cell of each efficiency level in the battery type corresponding to the cell under test, subtracting the actual current density of the sampled cell at the actual external quantum efficiency from the product of the substrate absorptivity Abb of the sampled cell and the lossless current density Jideal, to obtain the second collection loss current density lost by the sampled cell due to substrate collection. That is, for a sampled cell, there exists Formula 1.

[0060] J 第二收集损失电流密度 =Jideal ⅹ Abb–J 实际EQE (Formula 1)

[0061] This allows for the accurate determination of the second collection loss current density of the sampled solar cell due to collection by the substrate.

[0062] In some embodiments, prior to step S4, the method may further include: step S6, where obtaining the wavelength absorptivity Abb of the substrate of the sampled solar cell in step S4 may include: step S41. Step S6: Measure the measured fill factor, measured open-circuit voltage, reflectivity, and transmittance of each of the aforementioned sampled solar cells. Step S41: For each sampled solar cell of each efficiency level in the battery type corresponding to the solar cell under test, adjust the simulation parameters until the ratio of the simulated fill factor to the measured fill factor of the sampled solar cell, and the ratio of the simulated open-circuit voltage to the measured open-circuit voltage of the sampled solar cell are all within a preset range. In this case, combine the transmittance and reflectivity of the sampled solar cell to obtain the simulated absorptivity of the sampled solar cell; the simulated fill factor and the simulated open-circuit voltage of the sampled solar cell are simulated from the reflectivity of the sampled solar cell.

[0063] Specifically, step S6 can employ either contact or non-contact measurement, with no limitation on the method. Step S41 can be performed using simulation software such as Quakka3. In this software, by inputting the cell type or relevant process parameters of the sampled cell, as well as reflectivity, the simulated fill factor and simulated open-circuit voltage of the sampled cell can be simulated. In step S41, for each sampled cell of each efficiency level within the cell type corresponding to the cell under test, the simulation parameters can be adjusted in the same simulation software such as Quakka3 until the ratio of the simulated fill factor to the measured fill factor, and the ratio of the simulated open-circuit voltage to the measured open-circuit voltage, are all within preset ranges. In this case, the performance characteristics of the simulated cell can be considered to be substantially similar to those of the sampled cell, and the simulated cell can be approximated as the sampled cell. Here, adjusting the simulation parameters refers to adjusting parameters of the cell structure characteristics other than the reflectivity. In this case, by adjusting the simulation parameters and combining them with the transmittance and reflectance of the sampled solar cell, the simulated absorptivity of the sampled solar cell is obtained. That is to say, the absorptivity Abb of the substrate of the aforementioned sampled solar cell for the wavelength is obtained through simulation and calibration.

[0064] The preset range here indicates that, for the same sampled solar cell, the simulated fill factor and the measured fill factor are approximately equal, as are the simulated open-circuit voltage and the measured open-circuit voltage. For example, this preset range can be from 0.9 to 1.1, and the specific size of this preset range is determined based on factors such as test accuracy and cell type. The closer the preset range is to 1, the higher the test accuracy of the solar cell under test is likely to be. For example, the preset range can be 0.9, 0.92, 0.95, 0.98, 0.99, 1, 1.01, 1.02, 1.05, 1.08, or 1.1.

[0065] In some embodiments, for each sampled battery cell of each efficiency level within the battery type corresponding to the battery cell under test, the absolute value of the difference between the second photoluminescence intensity value of the sampled battery cell under a preset number of standard sunlight intensities, the calculated short-circuit current density determined by calculating the collection loss current density in steps 203 and 2031 corresponding to the battery type, and the measured short-circuit current density, is less than or equal to 0.50 mA / cm². 2 The calculated current density is obtained from the second photoluminescence intensity value of the sampled solar cell under a preset standard solar intensity, based on the linear regression equation corresponding to the battery type. It is noted that for each sampled solar cell of each efficiency level within the battery type corresponding to the tested solar cell, the linear regression equations in steps 203 and 2031 above have high accuracy; the absolute value of the difference is less than or equal to 0.50 mA / cm². 2 This can be used as a termination condition for determining the aforementioned linear regression equation to improve the testing accuracy of the battery cell under test. Here, the calculated short-circuit current density, determined by calculating the collection loss current density, can be calculated by subtracting the loss current density of the battery cell from the loss current density of the sampled battery cell, based on the calculated collection loss current density of the sampled battery cell obtained in the aforementioned short-circuit current density example. The measured short-circuit current density of the sampled battery cell can be the short-circuit current density obtained through contact measurement methods, etc. For example, the short-circuit current density of the sampled battery cell can be obtained through contact measurement using a probe. For example, for each sampled battery cell of each efficiency level in the battery type corresponding to the battery cell under test, the absolute value of the difference between the calculated short-circuit current density determined by calculating the collection loss current density and the measured short-circuit current density can be 0 or 0.01 mA / cm². 2 0.05mA / cm 2 0.1mA / cm 2 0.12mA / cm 2 0.15mA / cm 2 0.19mA / cm 20.20mA / cm 2 0.22mA / cm 2 0.25mA / cm 2 0.3mA / cm 2 0.35mA / cm 2 0.4mA / cm 2 0.42mA / cm 2 0.45mA / cm 2 0.50mA / cm 2 .

[0066] It should be noted that if the absolute value of the difference between the calculated short-circuit current density determined by the calculated collection loss current density and the measured short-circuit current density is greater than 0.5, it indicates that the accuracy of the linear regression equation is low. This may be due to the large light intensity step value between adjacent standard solar intensities in step S2, resulting in fewer data pairs for the simulated linear regression equation. Therefore, the light intensity step value should be reduced, a new preset standard solar intensity with the most linear correlation should be found, and a new linear regression equation should be fitted until the absolute value of the difference between the calculated short-circuit current density determined by the calculated collection loss current density and the measured short-circuit current density is less than or equal to 0.50 mA / cm². 2 .

[0067] Step 204: Substitute the first photoluminescence intensity value into the linear regression equation to calculate the collection loss current density of the battery cell under test due to collection by the substrate.

[0068] Therefore, the linear regression equation is used to calculate the first collection loss current density of the tested solar cell due to the substrate collection, which is simpler and more accurate.

[0069] This application also provides a testing system for solar cells, which can implement any of the aforementioned testing methods for solar cells. The testing system may include: a first photoluminescence intensity value acquisition module, used to acquire a first photoluminescence intensity value of the solar cell under test under a preset number of standard solar intensities; the solar cell under test includes: a substrate; the preset number of standard solar intensities is less than or equal to 1 standard solar intensity; and a calculation module, used to calculate, based on the first photoluminescence intensity value, a first collection loss current density of the solar cell under test due to collection by the substrate using a linear regression method.

[0070] In some embodiments, the first photoluminescence intensity value acquisition module includes: a photoluminescence intensity value tester, which can be used to test and obtain the first photoluminescence intensity value of the battery cell under test under a preset number of standard solar irradiances.

[0071] In some embodiments, the photoluminescence intensity tester and the calculation module can be integrated into a single device.

[0072] It should be noted that this testing system can implement any of the aforementioned battery cell testing methods and has the same or similar beneficial effects as any of the aforementioned battery cell testing methods. The relevant parts can be referred to each other. In order to avoid repetition, they will not be described again here.

[0073] The following is combined with Figures 3 to 5 The present application will be further explained in conjunction with specific embodiments.

[0074] First, ensure that the mechanical parameters of the testing equipment, such as QE (quantum efficiency) and PL (photoluminescence intensity), are consistent across all testing stations. Specifically, these testing stations are used to perform corresponding tests or measurements on sampled solar cells of different efficiency levels corresponding to the type of solar cell being tested. By adjusting the mechanical parameters of the testing equipment, the consistency of measurements on the sampled solar cells can be ensured.

[0075] For a given battery type, sampled cells at three efficiency levels are selected, with five sampled cells at each efficiency level. The three efficiency levels are: the average efficiency level for this battery type, the higher-than-average efficiency level for this battery type, and the lower-than-average efficiency level for this battery type. Specifically, the average efficiency level is 27%, the higher-than-average efficiency level is 27.2%, and the lower-than-average efficiency level is 26.8%. The difference between the higher-than-average efficiency and the lower-than-average efficiency is 0.2%. Therefore, for this battery type, five sampled cells with an efficiency level of 27%, five with an efficiency level of 27.2%, and five with an efficiency level of 26.8% are selected, for a total of 15 sampled cells.

[0076] For each of the 15 sampled solar cells, the measured fill factor (pFF) and measured open-circuit voltage (Voc) were obtained. For each of the 15 sampled solar cells, the reflectivity (R) and transmittance (T) were obtained by measuring the quantum efficiency (QE).

[0077] For each of the 15 sampled solar cells, the reflectance R of the sampled cell was input into the solar cell simulation software Quakka3. The simulation parameters were adjusted until the ratio of the simulated fill factor to the measured fill factor, and the ratio of the simulated open-circuit voltage to the measured open-circuit voltage of the sampled cell, were all within the range of 0.95 to 1.05. Under these conditions, the simulated absorptivity of the sampled cell was obtained by combining the measured transmittance and reflectance.

[0078] For each of the 15 sampled cells, the second collection loss current density lost by the sampled cell due to substrate collection is calculated using the aforementioned Formula 1.

[0079] For each of the 15 sampled solar cells, 20 second photoluminescence intensity values ​​were measured at 20 different standard solar intensities, starting from 0.002 standard solar intensities (sun) to 1 standard solar intensity. Table 1 below shows only 5 of the 20 second photoluminescence intensity values ​​measured for each of the 15 sampled solar cells. Table 1 also shows the measurement results of the second collection loss current density lost due to substrate collection in the 15 sampled solar cells. In Table 1, the unit of the second collection loss current density is mA / cm². 2 The first of the two numbers in the serial number is used to represent different efficiency levels: 1 represents low efficiency, 2 represents average efficiency, and 3 represents high efficiency. 1-1 to 1-5 represent 5 sampled cells in the low efficiency level, 2-1 to 2-5 represent 5 sampled cells in the average efficiency level, and 3-1 to 3-5 represent 5 sampled cells in the high efficiency level.

[0080] Table 1: Partial Measurement Results of Sampled Battery Cells

[0081]

[0082] For each of the 15 sampled solar cells, there is a corresponding second collection loss current density and 20 second photoluminescence intensity values. For each of the 15 sampled solar cells, from the 20 second photoluminescence intensity values ​​corresponding to each sampled solar cell, the same preset standard solar intensity corresponding to the second photoluminescence intensity value with the highest linear correlation to the collection loss current density lost due to substrate collection for each sampled solar cell is determined. This same preset standard solar intensity is 0.02 standard solar intensities.

[0083] Reference Figure 4 For the 15 sampled solar cells, the corresponding cell type was determined, and the second photoluminescence intensity value under 0.02 standard solar intensity was correlated with the collection loss current density lost due to substrate collection for that cell type by a linear regression equation. Figure 4 In this study, the cell types corresponding to the 15 sampled solar cells were determined. The linear regression equation between the second photoluminescence intensity value at 0.02 standard solar intensity and the collection loss current density lost due to substrate collection for that cell type is Y = -1013.8X + 410.52. In this linear regression equation, Y represents the second photoluminescence intensity value at 0.02 standard solar intensity for the cell types corresponding to the 15 sampled solar cells, and X represents the collection loss current density lost due to substrate collection for that cell type. The unit of X can be mA / cm². 2 (milliamperes per square centimeter). The goodness of fit R of the linear regression equation is... 2 =0.8543.

[0084] Reference Figure 5 And as shown in Table 2 below, for each of the 15 sampled solar cells, its second photoluminescence intensity value at 0.02 standard solar intensity was substituted into the linear regression equation Y = -1013.8X + 410.52 to calculate the calculated collection loss current density due to substrate collection. Then, using the aforementioned lossless current density (Jideal), the calculated short-circuit current density was calculated by subtracting the loss current density of the solar cell. The absolute value of the difference between the calculated short-circuit current density and the measured short-circuit current density of the sampled solar cell is less than or equal to 0.50 mA / cm². 2 If the test calibration is successful, it indicates that the linear regression equation has high accuracy and can be directly used for subsequent electrical testing of this type of battery. The measured short-circuit current density obtained from the sampled battery cells here is obtained through a contact method.

[0085] Table 2: Partial Measurement Results of Sampled Battery Cells

[0086]

[0087] It should be noted that the definition of the serial number in Table 2 above is the same as that in Table 1 above.

[0088] It should be noted that for this type of solar cell, the entire preceding process constitutes calibration before electrical performance testing. The purpose is to find a preset standard light intensity (0.02 standard light intensity) corresponding to the second photoluminescence intensity value that is most linearly correlated with the first collection loss current density, ensuring the accuracy of the electrical performance test. Subsequent electrical tests on this type of solar cell can be performed using a non-contact testing method to obtain the photoluminescence intensity value at 0.02 standard solar intensity. This value can then be directly substituted into the linear regression equation Y = -1013.8X + 410.52 to calculate the first collection loss current density due to substrate collection. This, combined with other losses, can then be used to calculate the short-circuit current density and other electrical parameters of the solar cell. The testing method provided in this application offers fast testing speed and high accuracy.

[0089] The standard solar intensity of the photoluminescence intensity tester for the 15 sampled solar cells was adjusted to 0.02 times the standard solar intensity to calibrate the tester.

[0090] For each of the 15 sampled solar cells of the corresponding battery type, a calibrated photoluminescence intensity meter was used to obtain the first photoluminescence intensity value of the solar cell under 0.02 standard solar irradiance. Then, the first photoluminescence intensity value of the solar cell under 0.02 standard solar irradiance was used as Y and substituted into the linear regression equation Y = -1013.8X + 410.52 to calculate the first collection loss current density X of the solar cell under test due to the substrate collection.

[0091] Next, for each of the 15 sampled battery cells corresponding to the battery type under test, based on obtaining the first collection loss current density lost by the battery cell under test due to the substrate collection, the aforementioned lossless current density J is used. i d ea The short-circuit current density of the cell under test is further determined by subtracting the loss current density of the cell from the value of l. Then, electrical parameters such as short-circuit current and photoelectric conversion efficiency are determined.

[0092] In this embodiment, for each of the 15 sampled solar cells corresponding to different battery types, the first collection loss current density, short-circuit current density, short-circuit current, and photoelectric conversion efficiency of the solar cell under test can be accurately calculated solely from the first photoluminescence intensity value of the solar cell under test at 0.02 standard sunlight intensity. The first photoluminescence intensity value of the solar cell under test at 0.02 standard sunlight intensity can be measured using a photoluminescence intensity value tester, without the need for other measurements. The entire testing process is non-contact, and since probes are not used extensively, the risk of short circuits caused by incorrect positive and negative electrode connections due to overly dense probes is avoided, and the probe-related risks are also eliminated. The difficulty of precisely aligning the test points of the solar cell is a major obstacle. Therefore, the solar cell testing method provided in this application is applicable to various types of solar cells, with a wide range of applications, even for solar cells without a main grid. Secondly, since probes are not used extensively, test errors caused by poor probe contact are avoided. Thirdly, only the first photoluminescence intensity value of the solar cell under test needs to be obtained and used for calculation. The number of parameters required for testing the solar cell under test is small, thus greatly shortening the testing time and increasing testing efficiency. Fourthly, as can be seen from the comparison in Table 2, the short-circuit current density calculated by this method has high accuracy and strong repeatability compared with the measured short-circuit current density, making it suitable for testing solar cells of different grades.

[0093] It should be noted that, for the sake of simplicity, the method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments of this application are not limited to the described order of actions, because according to the embodiments of this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions involved are not necessarily essential to the embodiments of this application.

[0094] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0095] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0096] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method for testing battery cells, characterized in that, include: Obtain the first photoluminescence intensity value of the solar cell under test under a preset standard sunlight intensity; The battery cell to be tested includes: a substrate; the preset standard solar intensity is less than or equal to 1 standard solar intensity; Based on the first photoluminescence intensity value, the first collection loss current density of the battery cell under test due to collection by the substrate is calculated by linear regression.

2. The testing method for battery cells according to claim 1, characterized in that, Before the step of obtaining the first photoluminescence intensity value, the method further includes: For the battery type corresponding to the battery cell under test, within a range of less than or equal to 1 standard solar intensity, determine the preset number of standard solar intensities corresponding to the second photoluminescence intensity value that has the highest linear correlation with the collection loss current density lost due to substrate collection for the battery type.

3. The testing method for battery cells according to claim 1, characterized in that, Prior to the step of calculating the first collection loss current density, the method further includes: For the battery type corresponding to the battery cell under test, determine the linear regression equation between the photoluminescence intensity value under the preset standard sunlight intensity and the collection loss current density lost by the battery type due to substrate collection. The steps for calculating the first collection loss current density include: The first photoluminescence intensity value is substituted into the linear regression equation to calculate the collection loss current density of the battery cell under test due to collection by the substrate.

4. The testing method for battery cells according to claim 2, characterized in that, Before the step of determining the preset number of standard solar intensities corresponding to the second photoluminescence intensity value with the highest linear correlation, the method further includes: For multiple sampled cells of various efficiencies corresponding to the battery type of the cell under test, determine the second collection loss current density lost by each sampled cell due to the collection by the substrate; For each sampled battery cell of each efficiency level in the battery type corresponding to the battery cell under test, multiple second photoluminescence intensity values ​​of each sampled battery cell are measured from the initial standard solar intensity to 1 standard solar intensity; the initial standard solar intensity is greater than 0 and less than or equal to 0.005 standard solar intensities. The step of determining the preset number of standard solar intensities corresponding to the second photoluminescence intensity value with the highest linear correlation includes: For multiple sampled cells of various efficiencies in the battery type corresponding to the battery cell under test, the same preset standard solar intensity is determined from the multiple second photoluminescence intensity values ​​of the sampled cells that has the highest linear correlation with the second photoluminescence intensity value of each sampled cell that has the highest collection loss current density due to substrate collection.

5. The testing method for battery cells according to claim 3, characterized in that, Prior to the step of determining the linear regression equation, the method further includes: For multiple sampled cells of various efficiencies corresponding to the battery type of the cell under test, determine the second collection loss current density lost by each sampled cell due to the collection by the substrate; The steps to determine the linear regression equation include: For multiple sampled cells of various efficiencies corresponding to the battery type under test, a linear regression equation is determined for the second photoluminescence intensity value of each sampled cell under the preset standard solar intensity and the collection loss current density lost by the battery type due to substrate collection.

6. The testing method for battery cells according to claim 4 or 5, characterized in that, Before the step of determining the second collection loss current density, the method further includes: For multiple sampled cells of various efficiencies corresponding to the battery type under test, the absorption rate of the substrate to the wavelength and the actual current density of each sampled cell at the actual external quantum efficiency are obtained. Obtain the lossless current density of the battery type corresponding to the battery cell under test at the ideal external quantum efficiency; The step of determining the second collection loss current density includes: For each sampled cell of each efficiency level in the battery type corresponding to the tested cell, based on the absorption rate of the substrate to the wavelength of the sampled cell, the lossless current density, and the actual current density of the sampled cell at the actual external quantum efficiency, the second collection loss current density lost by the sampled cell due to the substrate collection is determined.

7. The testing method for battery cells according to claim 6, characterized in that, Prior to the step of obtaining the absorption rate, the method further includes: The measured fill factor, measured open-circuit voltage, reflectivity, and transmittance of each sampled solar cell were obtained. The steps to obtain the absorption rate include: For each sampled cell of each efficiency level within the battery type corresponding to the tested cell, the simulation parameters are adjusted until the ratio of the simulated fill factor to the measured fill factor of the sampled cell, and the ratio of the simulated open-circuit voltage to the measured open-circuit voltage of the sampled cell, are all within a preset range. Under these conditions, the simulated absorptivity of the sampled cell is obtained by combining the transmittance and reflectance of the sampled cell. The simulated fill factor and simulated open-circuit voltage of the sampled cell are simulated from the reflectance of the sampled cell.

8. The testing method for battery cells according to claim 6, characterized in that, The step of determining the second collection loss current density includes: For each sampled cell of each efficiency level in the battery type corresponding to the tested cell, the product of the absorption rate of the substrate of the sampled cell to the wavelength and the lossless current density is used, and the actual current density of the sampled cell at the actual external quantum efficiency is subtracted to obtain the second collection loss current density of the sampled cell due to the collection by the substrate.

9. The test method for battery cells according to claim 4 or 5, characterized in that, For the battery type corresponding to the battery cell to be tested, the sampled battery cells cover at least three efficiency levels. The at least three efficiency levels include: a first efficiency level that accounts for more than 50% of the battery type corresponding to the tested battery cell, a second efficiency level that is higher than the first efficiency level, and a third efficiency level that is lower than the first efficiency level; the difference between the second efficiency level and the first efficiency level, and the difference between the first efficiency level and the third efficiency level are all less than or equal to 0.4%.

10. The testing method for battery cells according to claim 4, characterized in that, The steps for measuring the second photoluminescence intensity value include: For each sampled cell of each efficiency level in the battery type corresponding to the tested cell, starting from the initial standard solar intensity to one standard solar intensity, at least 15 second photoluminescence intensity values ​​of each sampled cell are measured at at least 15 different standard solar intensities.

11. The testing method for battery cells according to claim 5, characterized in that, For each sampled battery cell of each efficiency level within the battery type corresponding to the tested battery cell, the absolute value of the difference between the calculated short-circuit current density (determined by calculating the collected loss current density) and the measured short-circuit current density is less than or equal to 0.50 mA / cm². 2 The calculated collection loss current density is obtained by calculating the second photoluminescence intensity value of the sampled battery cell under a preset standard solar intensity, based on the linear regression equation corresponding to the battery type.

12. The test method for the battery cell according to any one of claims 1 to 5, 10, characterized in that, Also includes: The electrical parameters of the battery cell under test are determined based on the first collection loss current density lost by the substrate. The electrical parameters include at least one of the following: short-circuit current density, short-circuit current, and photoelectric conversion efficiency.

13. A testing system for solar cells, characterized in that, include: The first photoluminescence intensity value acquisition module is used to acquire the first photoluminescence intensity value of the battery cell under test under a preset number of standard sunlight intensities. The battery cell to be tested includes: a substrate; the preset standard solar intensity is less than or equal to 1 standard solar intensity; The calculation module is used to calculate the first collection loss current density of the battery cell under test due to collection by the substrate using a linear regression method based on the first photoluminescence intensity value.

14. The testing system for solar cells according to claim 13, characterized in that, The first photoluminescence intensity value acquisition module includes: a photoluminescence intensity value tester.

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