Solar cell series resistance test system

Abstract

The invention discloses a solar cell series resistance test system, which is used for solving the problem of limitation in electrical contact measurement of series resistance. The system comprises a transmission mechanism used for bearing and transmitting battery pieces; the test camera obscura is located above the transmission mechanism, and the bottom of the test camera obscura is open; the light source is located in the test camera obscura and is used for emitting light to the battery piece on the transmission mechanism, so that at least part of the area of the battery piece is illuminated; and the imaging component is positioned in the test camera obscura and is used for measuring the photoluminescence intensity value of the battery piece.

Description

[0001] This application is a divisional application of the patent application with the application number 202411426960.4 and the invention creation name "A Method and System for Measuring the Series Resistance of Solar Cells". The filing date of the patent application with the application number 202411426960.4 is October 14, 2024. Technical Field

[0002] The present invention relates to the technical field of solar cell testing, and in particular to a system for measuring the series resistance of solar cells. Background Art

[0003] The solar cell I-V tester is an important device in solar cell testing. It measures the current (I) and voltage (V) of the solar cell by simulating the irradiation of sunlight (AM1.5G), thereby obtaining the I-V characteristic curve of the solar cell and other performance parameters reflecting the quality of the cell. The main performance parameters obtained are short-circuit current (I sc ), open-circuit voltage (V oc ), fill factor (FF), photoelectric conversion efficiency (E ta ), series resistance (R s ), and parallel resistance (R sh ), etc. Among them, the series resistance R s is one of the important parameters of the solar cell. Its value will directly affect the output characteristics and conversion efficiency of the cell, and is of great significance for studying cell efficiency, optimizing cell structure, controlling process parameters, ensuring product quality, and improving cell performance.

[0004] Currently, the main method to obtain the series resistance R s of the solar cell is as follows: First, the electrodes of the cell are completely contacted through an electrical contact type fixture (such as a probe type fixture and a PCB board type fixture). Using the photovoltaic effect, the current and voltage of the cell under constant light illumination are measured to obtain the I-V characteristic curve, and then the series resistance R s is calculated through the I-V characteristic curve and Ohm's law R = V / I. However, measuring some solar cells (such as non-main grid back contact cells) through an electrical contact type fixture is not very applicable. Summary of the Invention

[0005] The purpose of the present invention is to provide a system for measuring the series resistance of solar cells to solve the limitations existing in the electrical contact measurement of the series resistance, ensure the test accuracy, and reduce the fragmentation rate.

[0006] In the first aspect, the present invention also provides a system for measuring the series resistance of solar cells, including:

[0007] A transmission mechanism for carrying and transmitting the cell;

[0008] A test dark box is located above the transmission mechanism, and the bottom of the test dark box is open.

[0009] A light source is located inside the test dark box. The light source is used to emit light to the solar cell on the transmission mechanism so that at least part of the area of the solar cell is illuminated.

[0010] An imaging component is located inside the test dark box and is used to measure the photoluminescence intensity value of the solar cell.

[0011] In the case of adopting the above technical solution, the transmission mechanism transports the solar cell to directly below the open bottom of the test dark box. The light source emits light to the solar cell inside the test dark box so that at least part of the area of the solar cell is illuminated. The imaging component measures the illuminated solar cell to obtain the photoluminescence intensity value of the solar cell. Through this solar cell series resistance test system, the total photoluminescence intensity value and the local photoluminescence intensity value can be measured, which is convenient for calculating the series resistance according to the measured total photoluminescence intensity value and local photoluminescence intensity value subsequently. The entire area and at least one partial area of the first side of the solar cell are respectively irradiated and illuminated. Adopting a non-contact test method, using the principle that the photo-generated current generated in the illuminated area of the solar cell flows to the non-illuminated area and there is a potential difference between the illuminated area and the non-illuminated area, through the measured total photoluminescence intensity value, the fitted photoluminescence intensity value and the short-circuit current, and using Ohm's law, the series resistance R of the solar cell is finally calculated. s Compared with the existing contact-type fixture for contact measurement of the electrodes of the solar cell, since the series resistance test system in this application is used for non-contact testing, there will be no short circuit caused by incorrect connection of the positive and negative poles of the fixture to the electrodes of the solar cell, and there is no need to use a contact-type fixture. Therefore, it is not restricted by the density of the fine grids of the solar cell, there is no requirement for the accuracy of the contact fixture, and there will be no excessive external resistance caused by fewer probes of the contact fixture, which affects the test results. And there is no need to apply elastic pressure to ensure good contact between the probe and the electrode of the solar cell, reducing the fragmentation rate of the solar cell and protecting the electrode and the structure of the solar cell.

[0012] In some possible implementation manners, the solar cell series resistance test system further includes a mask plate mechanism, which is used to carry at least one mask plate and is used to drive the mask plate to move relative to the solar cell between the test dark box and the transmission mechanism to adjust the shielding area of the mask plate on the solar cell.

[0013] In the case of adopting the above technical solution, the mask plate mechanism drives at least one mask plate to sequentially move to the position between the test dark box and the transmission mechanism, that is, above the battery cell, so as to adjust the shielding area of the mask plate on the battery cell. During one shielding process, the light source emits light to the battery cell in the test dark box, so that the unshielded area of the battery cell is illuminated, and the imaging component measures the illuminated battery cell to obtain the photoluminescence intensity value of the battery cell. Through this solar cell series resistance test system, the total photoluminescence intensity value and the local photoluminescence intensity value can be measured, which is convenient for calculating the series resistance according to the measured total photoluminescence intensity value and local photoluminescence intensity value subsequently. By using the mask plate mechanism to irradiate and illuminate all areas and at least one partial area of the first side of the battery cell respectively, compared with the existing contact fixture for contact measurement of the battery cell electrodes, since the series resistance test system in this application is used for non-contact testing, there will be no short circuit caused by incorrect connection of the positive and negative poles of the fixture to the battery cell electrodes, and there is no need to use a contact fixture. Therefore, it is not limited by the density of the fine grids of the battery cell, there is no requirement for the accuracy of the contact fixture, and there will be no excessive external resistance caused by fewer probes of the contact fixture, which affects the test results. Moreover, there is no need to apply elastic pressure to ensure good contact between the probes and the electrodes of the battery cell, reducing the fragmentation rate of the battery cell and protecting the electrode and battery cell structure.

[0014] In some possible implementation manners, the mask plate mechanism includes:

[0015] A turntable that can rotate;

[0016] At least two mask plates are arranged on the turntable at intervals along the circumferential direction of the turntable. The rotation of the turntable drives at least two mask plates to alternately move to the position between the test dark box and the transmission mechanism, and the shielding areas formed by each mask plate on the battery cell are different.

[0017] In the case of adopting the above technical solution, the rotation of the turntable drives the mask plate thereon to alternately move to the position between the test dark box and the transmission mechanism, that is, directly above the battery cell. Different shielding areas are formed on the battery cell by different mask plates. After each irradiation and illumination is completed, the turntable rotates to move the next mask plate above the battery cell to complete the replacement operation of the mask plate. This mask plate mechanism has a simple structure and is convenient to operate.

[0018] In some possible implementation manners, at least two mask plates include a first mask plate and a second mask plate. The hollowed-out areas of the first mask plate and the second mask plate are both strip-shaped areas. The strip-shaped areas can be perpendicular to the length direction of the fine grids of the battery cell, and the projections of the hollowed-out areas of the first mask plate and the second mask plate on the same battery cell are alternately arranged.

[0019] In the case of adopting the above technical solution, the hollowed-out areas of the first mask plate and the second mask plate are strip-shaped areas, and the strip-shaped areas are perpendicular to the length direction of the fine grid. When the solar cell is blocked, the fine grid exposed from the hollowed-out area is complete in the length direction, which is convenient for subsequent calculation. Moreover, the projections of the hollowed-out areas of the first mask plate and the second mask plate on the same solar cell are alternately arranged, which can make the resistance of the light-receiving parts of the solar cell uniform twice, and the measured series resistance result is more accurate.

[0020] In some possible implementation manners, the at least two mask plates further include a third mask plate and a fourth mask plate. The hollowed-out area of the third mask plate is used to expose all areas of the first surface of the solar cell, and the fourth mask plate has no hollowed-out area. The fourth mask plate is used to block all areas of the first surface of the solar cell. With such a setting, when the third mask plate is moved above the solar cell, the hollowed-out area of the third mask plate is used to make all areas of the first surface of the solar cell receive light, and the total photoluminescence intensity value is measured. By moving the fourth mask plate above the solar cell to block all areas of the first surface of the solar cell, it is used to ensure that the photoluminescence intensity of the solar cell is zeroed before receiving light, which is convenient for improving the measurement accuracy.

[0021] In some possible implementation manners, the third mask plate, the first mask plate, the second mask plate, and the fourth mask plate are arranged in sequence along the circumferential direction of the turntable. With such a setting, according to the test sequence, the turntable rotates in the same direction, and the third mask plate, the first mask plate, the second mask plate, and the fourth mask plate are used for measurement in sequence. In this way, the reciprocating rotation of the turntable is avoided, and the test efficiency can be improved.

[0022] In some possible implementation manners, the light source is a matrix laser light source, and the emitted light rays are parallel light rays.

[0023] In some possible implementation manners, the light source can successively adjust the range of the emitted light rays, so that the emitted light rays successively irradiate at least one partial area on the first surface of the solar cell.

[0024] In some possible implementation manners, the light source is a laser light source, and the laser light source forms a light-receiving area and a non-light-receiving area on the solar cell by means of line laser scanning. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0026] Figure 1 It is a schematic flow chart of a method for testing the series resistance of a solar cell provided by an embodiment of the present invention;

[0027] Figure 2The schematic diagram of photoluminescence obtained after irradiating and receiving light on the entire area of the first side of the battery cell by the test method provided in the embodiment of the present invention;

[0028] Figure 3 The schematic diagram of photoluminescence obtained after irradiating and receiving light on the first part area of the first side of the battery cell by the test method provided in the embodiment of the present invention;

[0029] Figure 4 The schematic diagram of photoluminescence obtained after irradiating and receiving light on the second part area of the first side of the battery cell by the test method provided in the embodiment of the present invention;

[0030] Figure 5 The structural schematic diagram of a solar cell series resistance test system provided in the embodiment of the present invention;

[0031] Figure 6 For Figure 5 The top view schematic diagram of the test system in;

[0032] Figure 7 For Figure 5 The partial side view schematic diagram of the test system in;

[0033] Figure 8 For Figure 5 The structural schematic diagram of the first mask plate of the test system in;

[0034] Figure 9 For Figure 5 The structural schematic diagram of the second mask plate of the test system in;

[0035] Figure 10 The data comparison chart of the series resistance obtained by the test method in the embodiment of the present invention and the series resistance obtained by the existing contact test;

[0036] Figure 11 The data comparison chart of the series resistance obtained by the mask plate test and the series resistance obtained by the grating test in the embodiment of the present invention.

[0037] Reference numerals: 1 is a test dark box, 2 is a transmission mechanism, 3 is a mask plate mechanism, 31 is a turntable, 32 is a mask plate, 321 is a first mask plate, 322 is a second mask plate, 323 is a third mask plate, 324 is a fourth mask plate, 325 is a hollowed-out area, 4 is a battery cell. Detailed implementation manners

[0038] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] It should be noted that when an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0040] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined. "Several" means one or more unless otherwise specifically defined.

[0041] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention.

[0042] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] The existing main method for obtaining the series resistance R of a solar cell s is as follows: First, the electrodes of the cell are completely contacted through an electrical contact type fixture (such as a probe type fixture and a PCB board type fixture), and using the photovoltaic effect, the current and voltage of the cell under constant illumination conditions are measured to obtain the I-V characteristic curve, and then the series resistance R is calculated through the I-V characteristic curve and Ohm's law R = V / I. s of a solar cell obtained in a common laboratory sThe methods include the double-light-intensity method (1-Suns and 0.5-Suns) and the bright-dark field method (1-Suns and 0-Suns), etc. However, all the methods are based on the electrical contact method, using electrical measuring instruments such as ammeters and voltmeters to test the actual electrical parameters, and then calculating the series resistance through Ohm's law R = V / I. However, the measurement of some solar cells (such as the back-contact cell without main grid) by the electrical contact fixture is not very applicable, mainly for the following problems:

[0044] 1. The PN fine grids on the back of the back-contact cell without main grid are distributed in a finger-like pattern. Using a too dense probe-type fixture or a PCB board-type fixture may cause incorrect connection between the positive and negative poles of the fixture and the electrodes of the cell, easily resulting in short circuits. For relatively dense fine grids, the processing accuracy of the contact fixture cannot meet the test requirements.

[0045] 2. If a fixture with fewer probes or a PCB board is used to contact the local electrodes, it will lead to too large external resistance, affecting the test of the fill factor FF, and further affecting the test results.

[0046] 3. To ensure the test accuracy and repeatability of the back-contact cell without main grid, applying elastic pressure on the cell to ensure good contact between the probes and the electrodes of the cell greatly increases the fragmentation rate of the cell, and may also damage the passivation layer or electrodes of the cell, thus affecting the cell performance.

[0047] In view of the above problems, as shown in Figures 1-4 The embodiment of the present invention provides a method for testing the series resistance of a solar cell, including the following steps:

[0048] Step S100: Provide a cell, which has opposite first and second surfaces, and at least the first surface of the cell has electrodes. The electrodes can be grid electrodes, and the grid electrodes can include main grid electrodes and / or fine grid electrodes.

[0049] Step S200: As shown in Figure 2 Irradiate and illuminate the entire area of the first surface, and measure the total photoluminescence intensity value PL corresponding to the entire area. oc . Among them, a laser light source can be used to emit light onto the first surface of the cell, and through some means, the entire area of the first surface is illuminated. Then, the illuminated cell can be imaged and measured by a PL (photoluminescence intensity) tester to obtain an open-circuit photoluminescence map as shown in Figure 2 , and the total photoluminescence intensity value PL of the cell can be obtained from this photoluminescence map. oc .

[0050] Step S300: As shown in Figure 3 and Figure 4As shown, at least one partial area of the first side is irradiated and light-received under the same lighting conditions, and at least one local photoluminescence intensity value PL corresponding to each partial area is measured. p When there are at least two partial areas, the partial areas do not overlap. The lighting conditions in step S300 are the same as those in step S200. In step S300, each time of irradiation, only a partial area of the first side of the cell is light-received, and the remaining areas are not light-received. And if there are multiple irradiations, the light-received areas on the cell do not overlap each time of irradiation, and each light-received area corresponds to a local photoluminescence intensity value PL. p The operation of obtaining the local photoluminescence intensity value is the same as the operation of obtaining the total photoluminescence intensity value in step S200, and will not be elaborated here.

[0051] Step S400: Fit at least one local photoluminescence intensity value PL p to obtain a fitted photoluminescence intensity value PL characterizing the first side. That is, all the local photoluminescence intensity values PL obtained in step S300 p are fitted to obtain a fitted photoluminescence intensity value PL characterizing the first side.

[0052] Step S500: Obtain the short-circuit current I of the cell sc . For example, an I-V test can be performed on the cell to obtain the short-circuit current I of the cell sc . This I-V test is a traditional contact measurement. Only the short-circuit current needs to be measured, and the measurement accuracy of the short-circuit current is not affected by the probe contact and the electrode structure. Therefore, only the traditional contact measurement is used for the short-circuit current in step S500, and it will not have an adverse impact on the test results of the entire series resistance. Of course, a non-contact measurement method for the cell can also be used to obtain the short-circuit current I of the cell sc .

[0053] Step S600: Calculate the series resistance R of the cell according to the total photoluminescence intensity value PL oc , the fitted photoluminescence intensity value PL and the short-circuit current I sc . s .

[0054] In the case of adopting the above technical solution, the entire area and at least one partial area of the first side of the cell are respectively irradiated and light-received under the same lighting conditions. Using a non-contact test method, based on the principle that the photocurrent generated in the light-received area of the cell flows to the non-light-received area and there is a potential difference between the light-received area and the non-light-received area, through the measured total photoluminescence intensity value PL oc , the fitted photoluminescence intensity value PL and the short-circuit current I sc , and using Ohm's law, the series resistance R of the cell is finally calculated.s Compared with the existing contact fixture for contact measurement of the battery cell electrodes, since the test method for the series resistance in this application adopts a non-contact test method, there will be no short circuit caused by incorrect connection of the positive and negative poles of the fixture to the battery cell electrodes, and there is no need to use a contact fixture. Therefore, it is not restricted by the density of the fine grids of the battery cell, there is no requirement for the accuracy of the contact fixture, and there will be no excessive external resistance caused by fewer probes of the contact fixture, which affects the test results. Moreover, there is no need to apply elastic pressure to ensure good contact between the probes and the electrodes of the battery cell, reducing the fragmentation rate of the battery cell and protecting the electrode and the battery cell structure.

[0055] In some embodiments, in step S300, when a partial area of the first surface is irradiated and light-received under the same light condition to obtain a local photoluminescence intensity value PL corresponding to this partial area p when, in step S400, at least one local photoluminescence intensity value PL p is fitted to obtain a fitted photoluminescence intensity value PL representing the first surface. Specifically, this local photoluminescence intensity value PL p is used as the fitted photoluminescence intensity value, that is, PL = PL p In step S600, according to the total photoluminescence intensity value PL oc , the fitted photoluminescence intensity value PL, and the short-circuit current I sc a specific step for calculating the series resistance R of the battery cell s is as follows:

[0056] Step S601, substitute the total photoluminescence intensity value PL oc , the fitted photoluminescence intensity value PL, and the short-circuit current I sc into formula (1) to calculate the series resistance R of the battery cell s ;

[0057]

[0058] where, V t is the thermal voltage, R s is the series resistance, I sc is the short-circuit current, PL is the fitted photoluminescence intensity value, PL oc is the total photoluminescence intensity value, V t = KT / q = 0.02568, V t is a known number. Among them, K is the Boltzmann constant, T is the thermodynamic temperature of the battery cell, q is the electron charge, T and q can both be measured in advance and are known values. This formula (1) is a deformation formula of Ohm's law. After taking the logarithm of the photoluminescence intensity value, the corresponding voltage value can be obtained. Given the voltage and the short-circuit current, the series resistance R can be calculated through calculation.s .

[0059] Using the above formula (1) to calculate the series resistance is applicable to the case where the cell is only partially shaded once. At this time, assuming that the resistances of each region on the cell are relatively uniform, therefore, light can be irradiated on only a partial region on the first side of the cell to obtain the local photoluminescence intensity value PL of this partial region p , and the series resistance R representing the entire cell is calculated using formula (1) s . Since only a partial region is irradiated with light once in this method, therefore, the series resistance R of the cell can be quickly measured s , improving the test efficiency of the series resistance

[0060] In some other embodiments, in step S300, when at least two partial regions on the first side are irradiated with light under the same light conditions to obtain at least two local photoluminescence intensity values PL corresponding to the respective partial regions p , another specific step of calculating the series resistance R of the cell according to the total photoluminescence intensity value PL oc , the fitting photoluminescence intensity value PL, and the short-circuit current I sc is as follows s :

[0061] Step S602, substituting the total photoluminescence intensity value PL oc , the fitting photoluminescence intensity value PL, and the short-circuit current I sc into formula (2) to calculate the series resistance R of the cell s ;

[0062]

[0063] where V t is the thermal voltage, R s is the series resistance, I sc is the short-circuit current, PL is the fitting photoluminescence intensity value, PL oc is the total photoluminescence intensity value, V t = KT / q = 0.02568, V t is a known number, where K is the Boltzmann constant, T is the thermodynamic temperature of the cell, q is the electron charge, T and q can both be measured in advance and are known values. This formula (2) is a deformation formula of Ohm's law. After taking the logarithm of the photoluminescence intensity value, the voltage value can be correspondingly obtained. Given the voltage and short-circuit current, the series resistance R can be calculated through calculation s .

[0064] The series resistance is calculated using the above formula (2), which is applicable to the cases where the resistance of the cell is uniform or non-uniform. At least two partial regions on the first side of the cell are irradiated with light under the same illumination conditions, and these partial regions do not overlap, so as to obtain the local photoluminescence intensity value PL corresponding to each partial region. p When this is the case, the series resistance R characterizing the entire cell can be calculated using formula (2). s This method can obtain the series resistance more accurately.

[0065] This embodiment provides a specific way to irradiate and receive light on a partial region of the first side of the cell. Specifically, the step of irradiating and receiving light on at least one partial region of the first side under the same illumination conditions in step S300 is as follows:

[0066] Step S310: Successively and proximally block different blocking regions on the first side through at least one mask plate, so that the unblocked regions on the first side are irradiated with light under the same illumination conditions. That is to say, the mask plate is brought close to the first side of the cell to form a blocking region and an unblocked region on the first side. The light source irradiates the entire first side of the cell, and the light can only irradiate on the unblocked region of the cell, and the unblocked region of the cell forms a partial region that receives light. The hollow regions of different mask plates are different and do not overlap, so the corresponding blocking regions and unblocked regions formed on the cell are different and do not overlap, that is, the partial regions that receive light do not overlap. It should be noted that at least one mask plate can be one or more; when there is only one mask plate, this mask plate can only perform one proximal block of one blocking region on the first side, or can successively and proximally block different blocking regions on the first side through one mask plate multiple times. When there are multiple mask plates, that is, at least two, each mask plate performs one block, and these mask plates can successively and proximally block different blocking regions on the first side multiple times.

[0067] This method directly blocks the cell through the mask plate. Since the mask plate is close to the cell, the accuracy of the blocking pattern is easy to control, and it can be applicable to various lights, such as parallel light or scattered light, etc., and it is not easy to irradiate on the cell outside the hollow region of the mask plate.

[0068] The data obtained by testing the cell through the method of blocking with this mask plate is compared with the data obtained by the existing method of testing with a contact fixture, and the test data is shown in Table 1 below:

[0069] Table 1. Comparison of test data between the method of blocking the cell with a mask plate and the method of testing with a contact fixture

[0070]

[0071]

[0072] Plotted based on the series resistance data in Table 1 Figure 10 , as Figure 10 shown, the correlation coefficient of the series resistance obtained by the two testing methods is 0.9394, indicating a good correlation, which shows that the test results of the non-contact testing method for the mask plate are highly accurate.

[0073] Another embodiment provides another specific way to irradiate and receive light on a partial area of the first side of the solar cell. Specifically, the step of irradiating and receiving light on at least one partial area of the first side under the same light condition in step S300 is as follows:

[0074] Step S320, successively and proximally blocking the light source by at least one mask plate, so that the light emitted by the light source under the same light condition passes through the hollow pattern of the mask plate and irradiates on at least one partial area of the first side. That is to say, by directly blocking the light source with the mask plate, the range of the light emitted by the light source is adjusted, so that the light of the light source passes through the hollow pattern of the mask plate and irradiates on a partial area of the solar cell. The light source is preferably a surface array laser light source, and the emitted light is parallel light. This method can be simply referred to as the grating method. It should be noted that at least one mask plate can be one or more; when there is only one mask plate, the mask plate can block the light source proximally only once, so that the light passes through the hollow pattern and irradiates on a partial area of the first side, or the mask plate can successively and proximally block different positions of the light source multiple times, so that the light passes through the hollow pattern and irradiates on different partial areas of the first side. When there are multiple mask plates, that is, at least two, each mask plate blocks the light source once, and these mask plates can successively and proximally block different positions of the light source multiple times, so that the light passes through the hollow pattern and irradiates on different partial areas of the first side.

[0075] The series resistance obtained by testing with the grating method is compared with the series resistance obtained by testing with the method of blocking the solar cell with the mask plate in the embodiment of the present application. As Figure 11 shown, it can be seen that the correlation coefficient of the series resistance obtained by the two methods is 0.98, indicating a good correlation, which shows that the test results of both the non-contact testing with the mask plate and the non-contact testing with the grating method are highly accurate.

[0076] In yet another embodiment, another specific way to irradiate and receive light on a partial area of the first side of the solar cell is provided. Specifically, the step of irradiating and receiving light on at least one partial area of the first side under the same light condition in step S300 is as follows:

[0077] Step S330: By successively adjusting the range of the emitted light of the light source, the emitted light is successively irradiated on at least one partial area of the first surface. That is to say, instead of adjusting the light-receiving area on the cell through a mask plate, the range of the emitted light of the light source itself is adjusted, such as in the way of line laser scanning, which equivalently forms a local shielding effect on the cell, so that a light-receiving area and a non-light-receiving area are formed on the cell. This method can also be applied to the calculation formula of the series resistance in this application. It should be noted that the range of the emitted light of the light source can be adjusted only once or multiple times.

[0078] In some embodiments, when a mask plate is used for local shielding of the cell, irradiating at least one partial area of the first surface under the same light condition in step S300 and measuring at least one local photoluminescence intensity value PL corresponding to each partial area p , specifically includes the following steps:

[0079] Step S311: As Figure 3 and Figure 8 shown, the first shielding area of the first surface is shielded by the first mask plate 321, so that the first partial area of the first surface that is not shielded is irradiated to receive light, and the first local photoluminescence intensity value PL corresponding to the first partial area is measured p1 ;

[0080] Step S312: As Figure 4 and Figure 9 shown, the second shielding area of the first surface is shielded by the second mask plate 322, so that the second partial area of the first surface that is not shielded is irradiated to receive light under the same light condition, and the second local photoluminescence intensity value PL corresponding to the second partial area is measured p2 ; wherein, the first shielding area and the second shielding area do not overlap, and the ratio of the first shielding area to the entire area of the first surface is a, the ratio of the second shielding area to the entire area of the first surface is b, and a + b = 1;

[0081] On this basis, fitting at least one local photoluminescence intensity value PL p in step S400 to obtain a fitting photoluminescence intensity value PL characterizing the first surface, specifically in step S401, the first local photoluminescence intensity value PL p1 and the second local photoluminescence intensity value PL p2 are used to calculate the weighted average through the formula PL = a × PL p1 + b × PL p2 to fit and obtain a fitting photoluminescence intensity value PL characterizing the first surface.

[0082] In the case of adopting the above technical solution, the first mask plate 321 and the second mask plate 322 are used to perform two occlusions successively. The occluded areas of the two occlusions do not overlap, and the sum of the proportions of the occluded areas of the two occlusions is equal to 1. By irradiating and exposing the solar cell after the two occlusions, two local photoluminescence intensity values PL are measured p The weighted average is calculated to obtain a fitted photoluminescence intensity value PL representing the entire solar cell. This fitted photoluminescence intensity value PL is the average photoluminescence intensity value of the entire solar cell. Compared with the fitted photoluminescence intensity value PL obtained by only performing one local occlusion, the accuracy of the fitted photoluminescence intensity value PL is improved, and the subsequent calculation of the series resistance R s is more accurate. In other words, when a + b = 1, the first partial area and the second partial area jointly form the entire area of the first surface, and the entire area of the first surface can be tested in two times, so that the test result can better reflect the series resistance R of the solar cell s .

[0083] Further, in this embodiment, the first occluded area can be greater than, equal to, or less than the second occluded area. The absolute value of the difference between a and b is greater than or equal to 0 and less than or equal to 0.2. That is, the sizes of the first occluded area and the second occluded area are not very different, which ensures the light-receiving balance of the two partial areas of the solar cell and the uniformity of the resistance of each light-receiving area. In addition, when the proportion of one of the partial areas is too small, the influence degree of the minority carrier lifetime on the PL test value will increase, and then the accuracy of the series resistance R s test will be reduced. Therefore, by reducing the size difference between the first occluded area and the second occluded area, the accuracy of the test result of the series resistance can be improved

[0084] Exemplarily, the proportion a of the first occluded area is 0.5, and the proportion b of the second occluded area is 0.5; or, the proportion a of the first occluded area is 0.45, and the proportion b of the second occluded area is 0.55; or, the proportion a of the first occluded area is 0.4, and the proportion b of the second occluded area is 0.6, etc. As long as the sizes of the first occluded area and the second occluded area are not very different, the accuracy of the test result of the series resistance can be further improved

[0085] Such as Figure 3 and Figure 4As shown, in some embodiments, both the first partial region and the second partial region are a plurality of strip-shaped regions perpendicular to the length direction of the fine grid of the cell. The first partial region and the second partial region are arranged alternately along the length direction of the fine grid. With such an arrangement, the strip-shaped regions of the first partial region and the second partial region are perpendicular to the fine grid direction, and there is no need to consider the angle of the non-occluded region relative to the fine grid, which is convenient for calculation. If the angle of the non-occluded region relative to the fine grid needs to be considered, the PL intensity component perpendicular to the length direction of the fine grid needs to be calculated, and the calculation process is relatively complex. Moreover, the first partial region and the second partial region are arranged alternately along the length direction of the fine grid, which improves the uniformity of the resistance of the first partial region and the second partial region, and the obtained series resistance result is more accurate.

[0086] In some embodiments, as Figure 8 and Figure 9 shown, the first mask plate 321 and the second mask plate 322 are different mask plates, and the first mask plate 321 and the second mask plate 322 successively replace and block different occluded regions of the first surface. Alternatively, the first mask plate and the second mask plate are the same mask plate, and the first mask plate moves and switches relative to the first surface in two different occluded regions.

[0087] In the case of adopting the above technical solution, the cell is occluded twice in two ways. When the ratios of the first occluded region and the second occluded region are different or the same, two different mask plates can be used. When the ratios of the first occluded region and the second occluded region are the same, the occlusion of different regions of the cell can be achieved by moving the position of one mask plate.

[0088] Of course, in addition to being able to occlude the cell twice, the cell can also be occluded three times, four times, five times, etc. more times. The light-receiving regions formed on the cell during each occlusion do not overlap, and the plurality of local photoluminescence intensity values PL p obtained after multiple occlusions and receiving light are all weighted averaged to fit and obtain the fitted photoluminescence intensity value PL.

[0089] As Figures 5-7 shown, the present invention also provides a solar cell series resistance testing system, which can be used to perform the solar cell series resistance testing method described in any of the above embodiments. The testing system includes a transmission mechanism 2, a testing dark box 1, a light source, and an imaging component; wherein, the transmission mechanism 2 is used to carry and transmit the cell 4; the testing dark box 1 is located above the transmission mechanism 2, the bottom of the testing dark box 1 is open, and the area of the open bottom is greater than or equal to the entire area of the cell 4 for aligning with the cell 4; the light source is located inside the testing dark box 1, and the light source is used to emit light to the cell 4 on the transmission mechanism 2 so that at least part of the region of the cell 4 receives light; the imaging component is located inside the testing dark box 1 and is used to image the cell 4 after receiving light to obtain a photoluminescence map, asFigures 2-4 as shown, and measure the photoluminescence intensity value of the cell.

[0090] When the test system works, the transmission mechanism 2 transmits the cell 4 and moves it to directly below the bottom opening of the test dark box 1, then stops transmitting. The light source emits light to the cell 4 in the test dark box 1, so that at least part of the cell 4 is illuminated. The imaging component images the illuminated cell 4 to obtain Figure 3 and Figure 4 the photoluminescence map as shown, and measure the photoluminescence intensity value of the cell 4.

[0091] Through this solar cell series resistance test system, the total photoluminescence intensity value and the local photoluminescence intensity value can be measured in a non-contact manner, which is convenient for calculating the series resistance according to the measured total photoluminescence intensity value and local photoluminescence intensity value subsequently. This solar cell series resistance test system adopts a non-contact measurement method and has the same beneficial effects as the first aspect, which will not be elaborated here.

[0092] In some embodiments, the solar cell series resistance test system further includes a mask plate mechanism 3, which is used to carry at least one mask plate 32 and drive the mask plate 32 to move relative to the cell 4 between the test dark box 1 and the transmission mechanism 2 to adjust the shielding area of the mask plate 32 on the cell 4.

[0093] When the test system works, the transmission mechanism 2 transmits the cell 4 and moves it to directly below the bottom opening of the test dark box 1, then stops transmitting. The mask plate mechanism 3 drives at least one mask plate 32 to successively move to the position between the test dark box 1 and the transmission mechanism 2, that is, above the cell 4 carried by the transmission mechanism 2, to adjust the shielding area of the mask plate 32 on the cell 4. During each shielding process, the light source emits light to the cell 4 in the test dark box 1, so that the unshielded area of the cell 4 is illuminated. The imaging component images the illuminated cell 4 to obtain Figure 3 and Figure 4 the photoluminescence map as shown, and measure the photoluminescence intensity value of the cell 4.

[0094] As Figures 5-7As shown, further, in some embodiments, the mask plate mechanism 3 includes a turntable 31 and at least two mask plates 32; wherein, the turntable 31 can rotate, specifically, the turntable 31 can be driven to rotate by a rotating motor or other power components; at least two mask plates 32 are arranged on the turntable 31 at intervals along the circumferential direction of the turntable 31, and the rotation of the turntable 31 drives at least two mask plates 32 to alternately move to the position between the test dark box 1 and the transmission mechanism 2. The hollowed-out areas of these mask plates 32 are different, and the shielding areas formed by each mask plate 32 on the battery cell 4 are different, that is, the locally illuminated areas formed are different, and the locally illuminated areas do not overlap.

[0095] When the mask plate mechanism works, the turntable 31 rotates to drive the mask plates 32 thereon to alternately move to the position between the test dark box 1 and the transmission mechanism 2, that is, to directly above the battery cell 4. Different shielding areas are formed on the battery cell 4 through different mask plates 32. After each irradiation and light reception, the turntable 31 rotates to move the next mask plate 32 above the battery cell 4 to complete the replacement operation of the mask plate 32. The structure of this mask plate mechanism 3 is simple and the operation is convenient.

[0096] As Figures 6-9 shown, exemplarily, at least two mask plates 32 include a first mask plate 321 and a second mask plate 322. The hollowed-out areas 325 of the first mask plate 321 and the second mask plate 322 are both strip-shaped areas. The strip-shaped areas can be perpendicular to the length direction of the fine grid of the battery cell 4 when the mask plate 32 rotates to above the battery cell 4, and the projections of the hollowed-out areas 325 of the first mask plate 321 and the second mask plate 322 on the same battery cell 4 are alternately arranged.

[0097] In the case of adopting the above technical solution, the hollowed-out areas 325 of the first mask plate 321 and the second mask plate 322 are strip-shaped areas, and the strip-shaped areas are perpendicular to the length direction of the fine grid. When the battery cell 4 is shielded, only the shielding ratio needs to be considered, and the angle of the hollowed-out area 325 relative to the fine grid does not need to be considered, which is convenient for subsequent calculations. If the angle of the hollowed-out area 325 relative to the fine grid needs to be considered, the PL intensity component perpendicular to the length direction of the fine grid needs to be calculated, and the calculation process is relatively complex. Moreover, the projections of the hollowed-out areas 325 of the first mask plate 321 and the second mask plate 322 on the same battery cell 4 are alternately arranged, which can make the resistance of the light-receiving parts of the battery cell 4 uniform twice, and the measured series resistance result is more accurate.

[0098] Of course, in addition to locally shielding the solar cell 4 through the first mask plate 321 and the second mask plate 322, the solar cell 4 can also be locally shielded by three, four, five or more mask plates 32. The multiple mask plates 32 are arranged along the circumferential direction of the turntable 31. As long as the space permits, the mask plates 32 do not interfere with each other when moving to the shielding position. The hollow areas 325 on the multiple mask plates 32 are all different.

[0099] As Figure 6 shown, further, at least two mask plates 32 further include a third mask plate 323 and a fourth mask plate 324. The hollow area of the third mask plate 323 is used to expose all areas of the first surface of the solar cell 4. The fourth mask plate 324 does not have a hollow area, and the fourth mask plate 324 is used to shield all areas of the first surface of the solar cell 4. With such a setting, when the third mask plate 323 moves above the solar cell 4, the hollow area of the third mask plate 323 is used to allow all areas of the first surface of the solar cell 4 to receive light, and the total photoluminescence intensity value PL oc is measured. By moving the fourth mask plate 324 above the solar cell to shield all areas of the first surface of the solar cell 4, it is used to ensure that the photoluminescence intensity of the solar cell 4 is reset to zero before receiving light, avoiding the superposition of the number of photons during the next light reception, and improving the measurement accuracy.

[0100] Of course, the third mask plate 323 may not be provided. When it is necessary to irradiate and receive light on all areas of the first surface of the solar cell 4, the first mask plate 321 and the second mask plate 322 can be moved away, and no mask plate 32 is provided above the solar cell 4. When the bottom opening of the test chamber 1 is relatively large and the distance between the actual power generation area on the solar cell 4 and the edge of the solar cell 4 is relatively large, the third mask plate 323 can be provided, and the ineffective area of the solar cell can be better shielded through the hollow area thereon to achieve better light reception testing. Of course, the fourth mask plate 324 may not be provided. After each light reception is completed, the light source can be turned off and a suitable stationary time can be set to enable the solar cell 4 to return to the initial state without light reception in the test chamber 1. The operation of turning off the light source and the stationary time can be omitted through the fourth mask plate 324, improving the test efficiency.

[0101] Further, in this embodiment, as Figure 6 shown, the third mask plate 323, the first mask plate 321, the second mask plate 322 and the fourth mask plate 324 are arranged in sequence along the circumferential direction of the turntable 31. With such a setting, according to the test sequence, the turntable 31 rotates in the same direction, and the third mask plate 323, the first mask plate 321, the second mask plate 322 and the fourth mask plate 324 are used for measurement in sequence, thus avoiding the reciprocating rotation of the turntable 31 and improving the test efficiency.

[0102] Of course, in addition to usingFigures 5-7 In addition to the turntable mode switching mask plate 32 shown, a linear drive structure can also be adopted, that is, multiple mask plates are arranged along the same straight line, and the mask plates are driven by a linear drive mechanism to move linearly in sequence above the battery cell for shielding. Or, only one mask plate is included, and the position of the mask plate relative to the battery cell is driven by a linear drive mechanism to adjust different shielding areas on the battery cell. As long as the adjustment of different shielding areas on the battery cell can be achieved, it is not limited to the structural forms listed in this embodiment.

[0103] It should be noted that the transmission mechanism 2 can be a conveyor belt or a transmission roller, and a positioning component can also be arranged on the transmission mechanism 2 for positioning the battery cell 4 below the test dark box 1 when the battery cell 4 moves below the test dark box 1.

[0104] In the description of the above embodiments, specific features, structures, materials or characteristics can be combined in a suitable manner in any one or more embodiments or examples.

[0105] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A solar cell series resistance test system, characterized in that: include: A transmission mechanism, used for carrying and transmitting the battery cells; A test dark box, located above the transmission mechanism, with an open bottom; A light source is located in the test dark box, and is used to emit light to the battery sheet on the transmission mechanism so that at least a part of the battery sheet is illuminated; The imaging component is located in the test dark box and is used to measure the photoluminescence intensity value of the cell.

2. The solar cell series resistance testing system according to claim 1, characterized in that: Also includes: The mask plate mechanism is used to carry at least one mask plate and to drive the position of the mask plate between the test dark box and the transmission mechanism to move relative to the battery cell to adjust the shielding area of ​​the mask plate on the battery cell.

3. The solar cell series resistance testing system according to claim 1, characterized in that: The mask plate mechanism comprises: Turntable, capable of rotating; At least two mask plates are arranged on the turntable at intervals along the circumferential direction of the turntable. The at least two mask plates are driven to move alternately to the position between the test darkroom and the transmission mechanism through the rotation of the turntable. The shielding area formed by each mask plate on the battery cell is different.

4. The solar cell series resistance testing system according to claim 3, characterized in that: The at least two mask plates include a first mask plate and a second mask plate, the hollow areas of the first mask plate and the hollow areas of the second mask plate are both strip areas, the strip areas can be perpendicular to the length direction of the fine grids of the battery cell, and the projections of the hollow areas of the first mask plate and the hollow areas of the second mask plate on the same battery cell are alternately arranged.

5. The solar cell series resistance testing system according to claim 4, characterized in that: The at least two mask plates further include a third mask plate and a fourth mask plate, wherein the hollow area of ​​the third mask plate is used to expose the entire area of ​​the first surface of the battery cell, and the fourth mask plate has no hollow area, and is used to cover the entire area of ​​the first surface of the battery cell; The third mask plate, the first mask plate, the second mask plate and the fourth mask plate are arranged in sequence along the circumferential direction of the turntable.

6. The solar cell series resistance testing system according to claim 1, characterized in that: The light source is a planar array laser light source, and the emitted light is parallel light.

7. The solar cell series resistance testing system according to claim 1, characterized in that: The light source can adjust the range of the emitted light successively, so that the emitted light is irradiated on at least a partial area on the first surface of the battery sheet successively.

8. The solar cell series resistance testing system according to claim 7, characterized in that: The light source is a laser light source, and the laser light source forms a light-receiving area and a non-light-receiving area on the battery cell by means of line laser scanning.

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