A method for determining laser damage to solar cells

Abstract

The present invention discloses a method and system for identifying laser damage to solar cells. The present invention first obtains spectral reflectance data of a solar cell after laser damage, obtained through measurement, and calculates theoretical scattering spectrum data of the solar cell based on the specified cell thicknesses of the GaInP layer and GaAs layer. Finally, based on the measured spectral reflectance data and the calculated theoretical scattering spectrum data, the solar cell damage is inverted by comparing the absorption peak characteristics of the visible light band and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve. The method and system of the present invention utilize the surface material properties and wavelength dimension resolution information provided by the scattering spectrum to reflect the material, and achieve damage identification of the solar cell by measuring the scattering spectrum of the solar cell before and after laser irradiation. The solution of the present invention is simple to implement and easy to implement in engineering and experimentally verify.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser damage assessment, and in particular relates to a method and system for distinguishing laser damage of solar cells. Background Art

[0002] Since the 1970s, scholars at home and abroad have conducted extensive research in the field of spectral detection and feature recognition of spacecraft targets. Research institutions have conducted laboratory measurements of the scattering spectra of numerous spacecraft materials and established corresponding spectral databases. Combined with scattering spectra data obtained from astronomical observation experiments, this data can be used to discriminate and analyze the surface material types of spacecraft targets, such as satellites and rocket bodies, in space environments, and even to infer changes in the surface material of spacecraft targets in space environments.

[0003] For solar cells in spacecraft systems, which have a large surface area and provide the energy to maintain normal spacecraft operation, damage to the cells will lead to a decline in their photoelectric performance, which in turn can cause malfunctions in the spacecraft. Lasers, as high-brightness light sources, often affect the photoelectric performance of solar cells when irradiated. When the irradiated laser energy is high enough, it can damage the cells, rendering their photoelectric performance unable to maintain normal spacecraft operation. In particular, when solar cells on non-cooperative target spacecraft are damaged by laser beam energy, traditional detection methods such as radar and optical imaging have difficulty identifying the specific damage to the cells. Therefore, a method is needed to determine the extent of laser damage to non-cooperative target solar cells. Summary of the Invention

[0004] In view of this, the object of the present invention is to discriminate the degree of laser damage to non-cooperative target solar cells.

[0005] To achieve the above-mentioned object, the present invention provides a method for identifying laser damage to a solar cell, comprising:

[0006] The step of obtaining spectral reflectance data of a solar cell after laser damage obtained by measurement;

[0007] The step of calculating theoretical scattering spectrum data of a solar cell according to the specified GaInP layer and GaAs layer cell thickness;

[0008] The step of inverting solar cell damage, in which the damage of the solar cell is inverted by comparing the absorption peak characteristics of the visible light band and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve based on the measured spectral reflectance data and the calculated theoretical scattering spectrum data.

[0009] Furthermore, in the step of calculating the theoretical scattering spectrum data of the solar cell according to the specified GaInP layer and GaAs layer cell thicknesses, each time the GaInP layer and GaAs layer cell thicknesses in the solar cell are specified, the step of calculating the theoretical scattering spectrum data of the solar cell includes:

[0010] Step S210: Calculate the complex refractive index N of each layer of the solar cell according to the incident angle θ0 and the geometric thickness of each layer of the solar cell. j and the incident angle θ of the jth layer j , the calculation formula is:

[0011] N j =n j -ik j ,

[0012]

[0013] Among them, the solar cell has k layers, j represents the jth layer space on the light path, j = 0, 1, 2, ..., k, k + 1, N0 is the complex refractive index of the medium in vacuum or atmospheric environment, θ0 is the incident angle of the incident light on the first layer of the solar cell, n j is the real refractive index of the jth layer of the solar cell, k j is the extinction coefficient of the jth layer of the solar cell, and i is an imaginary unit;

[0014] Step S220: Calculate the effective phase thickness δ of the jth layer j , the calculation formula is:

[0015]

[0016] Among them, d j is the thickness of the jth layer of the solar cell, and λ is the wavelength of the incident light;

[0017] Step S230: Calculate the admittance η of the jth layer j , the calculation formula is:

[0018]

[0019] Step S240: Calculate the spectral reflectance R total (θ i ,λ), the calculation formula is:

[0020]

[0021] Among them, R S (θ i ,λ) and R P (θ i,λ) represent the spectral reflectance of S-polarized wave and P-polarized wave respectively. j Substitute the following spectral reflectance R expression to obtain:

[0022]

[0023]

[0024] Furthermore, in the step of inverting the damage of the solar cell, a measured spectrum curve is obtained based on the spectral reflectance data obtained by measurement, and a simulated spectrum curve is obtained based on the theoretical scattering spectrum data obtained by calculation. The absorption peak characteristics of the visible light band of the measured spectrum curve and the simulated spectrum curve, and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve are compared. If they match, it indicates that the GaInP layer and GaAs layer battery thickness in the specified solar cell is the thickness of the solar cell after damage; if they do not match, the GaInP layer and GaAs layer battery thickness are re-specified, and the theoretical scattering spectrum data of the solar cell are calculated using the new GaInP layer and GaAs layer battery thickness, thereby obtaining a new simulated spectrum curve for comparison, until the absorption peak characteristics of the visible light band of the measured spectrum curve and the simulated spectrum curve, and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve are consistent, that is, until the thickness of the solar cell after damage is obtained.

[0025] The present invention also provides a solar cell laser damage identification system, comprising a solar cell surface scattering spectrum measurement device, a solar cell theoretical scattering spectrum data calculation module and a solar cell damage inversion module; wherein,

[0026] The solar spectrum measuring device is used to measure the spectral reflectance data of solar cells after laser damage.

[0027] The solar cell theoretical scattering spectrum data calculation module is used to calculate the theoretical scattering spectrum data of the solar cell according to the specified GaInP layer and GaAs layer cell thickness;

[0028] The solar cell damage inversion module is used to invert solar cell damage. The module inverts the solar cell damage based on the measured spectral reflectance data and the calculated theoretical scattering spectrum data by comparing the absorption peak characteristics of the visible light band and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve.

[0029] Furthermore, the solar cell surface scattering spectrum measurement device is an experimental measurement device, comprising a darkroom, a light source, a detector, a spectrum detection module, a three-dimensional motion platform, and a data acquisition and control module; wherein the light source, the detector, and the three-dimensional motion platform are placed in the darkroom;

[0030] During measurement, the laser-damaged solar cell is first placed on a three-dimensional motion platform. The data acquisition and control module controls the three-dimensional motion platform to move to the test position. The incident light emitted by the light source irradiates the solar cell, and the solar cell reflects the incident light. The detector receives the reflected light from the solar cell, and the reflected light information is introduced into the spectrometer in the spectrum detection module. After receiving the reflected light information transmitted by the detector, the spectrometer outputs the processed original scattered spectrum information to the data acquisition and control module. There are multiple test positions to ensure that all positions of the solar cell are measured. By processing the original scattered spectrum data measured multiple times, the spectral reflectance data of the solar cell after laser damage is obtained.

[0031] Furthermore, the three-dimensional motion platform includes a rotating platform, a first mechanical cantilever and a second mechanical cantilever, the rotating platform is used to fix the solar cell, the light source is set on the first mechanical cantilever, and the detector is set on the second mechanical cantilever; the data sampling and control module controls the position of the rotating platform, the first mechanical cantilever and the second mechanical cantilever, thereby controlling the azimuth rotation of the solar cell and / or measuring the change of the geometric model.

[0032] Furthermore, the first mechanical cantilever and the second mechanical cantilever constrain the light source and the detector within the same plane. The first mechanical cantilever and the second mechanical cantilever enable the detector to perform circular motion around the sample rotating platform, thereby receiving reflected light in the range of 0° to 360°.

[0033] Furthermore, the detector adopts a luminous flux detector, whose transmission channel includes a visible light channel and a near-infrared channel. The reflected light scattered by the solar cell under test is received by the detector. Correspondingly, the spectrometer includes a visible light spectrometer and a near-infrared spectrometer, which are respectively connected to the visible light channel and the near-infrared channel.

[0034] Furthermore, the light source includes a halogen lamp, a focusing bowl, an aperture and a power supply; the power supply supplies power to the halogen lamp and realizes current regulation of the halogen lamp, the focusing bowl focuses the light emitted by the halogen lamp into parallel light, which serves as incident light to illuminate the solar cell, the halogen lamp is located on the robotic arm of the three-dimensional motion platform, and the center position of the incident light coincides with the center of the solar cell placed on the three-dimensional motion platform; the aperture is used to limit the spot size of the incident light so that the incident light can completely illuminate the surface of the sample.

[0035] Furthermore, the darkroom is of fully enclosed design, and no other stray light enters the darkroom. The light source, detector, three-dimensional motion platform and walls placed in the darkroom are coated with matte paint.

[0036] The method and system of the present invention utilize the resolution information of the surface material properties and wavelength dimension of the material provided by the scattering spectrum, and realize damage identification of the solar cell by measuring the scattering spectrum of the solar cell before and after laser irradiation. The solution of the present invention is simple to implement and is conducive to engineering realization and experimental verification. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The present invention is a flow chart of the solar cell laser damage identification method.

[0038] Figure 2 Schematic diagram of the principle of calculating theoretical scattering spectrum data of a solar cell in an embodiment of the present invention.

[0039] Figure 3 This is a flow chart of a method for determining laser damage to a solar cell according to an embodiment of the present invention.

[0040] Figure 4 Schematic diagram of the structure of each layer of a triple-junction gallium arsenide solar cell in an embodiment of the present invention.

[0041] Figure 5 This is the effect of the DAR layer of the solar cell on the spectral reflectivity of the cell in the embodiment of the present invention.

[0042] Figure 6 This is the effect of the Ge layer of the solar cell on the spectral reflectivity of the cell in the embodiment of the present invention.

[0043] Figure 7 This is the effect of the GaInP and GaAs layers of the solar cell on the cell's spectral reflectivity in the embodiment of the present invention.

[0044] Figure 8 This is the characteristic change in thickness of the GaInP layer and the GaAs layer of the solar cell under laser irradiation in the embodiment of the present invention.

[0045] Figure 9 is a comparison of the simulation results of the solar cell scattering spectrum characteristics model and the experimental measurement results under different laser power densities in the embodiment of the present invention. 2 Comparison of simulation results; Figure 9(c) and Figure 9(d) are 0.42J / cm 2 Comparison of simulation results; Figure 9(e) and Figure 9(f) are 1.16J / cm 2 Comparison of simulation results; Figure 9(g) and Figure 9(h) are 1.58J / cm 2 Comparison of simulation results; Figure 9(i) and Figure 9(j) are 2.14J / cm 2 Comparison of simulation results; Figure 9(k) and Figure 9(l) are 2.96 J / cm 2 Comparison chart of simulation results.

[0046] Figure 10 This is a block diagram of the solar cell laser damage identification system of the present invention.

[0047] Figure 11 Schematic diagram of the principle of a device for measuring the surface scattering spectrum of a solar cell in an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0049] The method and system of the present invention utilize the resolution information of the surface material properties and wavelength dimension of the material provided by the scattering spectrum, and realize damage identification of the solar cell by measuring the scattering spectrum of the solar cell before and after laser irradiation.

[0050] Example 1

[0051] This embodiment is used to explain in detail the method for identifying laser damage to solar cells of the present invention.

[0052] like Figure 1 As shown, the method for distinguishing laser damage to solar cells of the present invention includes: a step of obtaining spectral reflectance data of the solar cell after laser damage obtained by measurement; a step of calculating theoretical scattering spectrum data of the solar cell according to the specified cell thicknesses of the GaInP layer and the GaAs layer; and a step of inverting the damage of the solar cell. In this step, the damage condition of the solar cell is inverted by comparing the absorption peak characteristics of the visible light band and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve based on the measured spectral reflectance data and the calculated theoretical scattering spectrum data.

[0053] In some specific embodiments of the present invention, the spectral reflectance data of the solar cell after laser damage is obtained by measuring with a ground experimental system. In other specific embodiments, the data is obtained by actually measuring a non-cooperative target solar cell.

[0054] The principle of calculating the theoretical scattering spectrum data of a solar cell based on the specified GaInP layer and GaAs layer cell thickness is as follows.

[0055] See also Figure 2 , the admittance matrix method is used to derive the quantitative relationship between the equivalent optical admittance Y of the solar cell multilayer structure and substrate combination and the structural parameters of each layer and substrate, as shown below:

[0056]

[0057] Where E0 is the electric field strength outside the first interface (the incident medium is air), E k+1is the electric field intensity outside the lower interface of the kth layer (exit medium), k is the number of film layers, η j is the admittance of the j-th layer of space, δ j is the effective phase thickness of the jth layer. In the formula, the matrix performs complex operations, where δ j The calculation formula is

[0058]

[0059] Where d is the thickness of each layer, N j is the complex refractive index of each layer, λ is the wavelength of the incident light, N j d j cosθ j is the optical phase thickness of the j-th interface.

[0060] The phase thickness is the same for both p-polarization (light vector E is in the plane of incidence) and s-polarization (light vector E is perpendicular to the plane of incidence). The solar cell has k layers, j represents the jth layer space on the light path, j = 0, 1, 2, ..., k, k + 1, such as Figure 2 In the four-layer solar cell shown, 0 represents the space where light enters, 1 represents the first layer of the solar cell, and 5 represents the space after light exits the fourth layer. Each layer reflects and refracts light. Layers 1-4 are all material and solid, while layers 0 and 5 are air or vacuum, devoid of matter. j is the admittance of the jth layer, which takes different forms for p-polarization and s-polarization, and we have

[0061]

[0062] The refraction angle θ of the jth layer j Determined by Snell's law, that is

[0063] N0 sinθ0=N j sinθ j =N s sinθ s

[0064] Where N0 is the complex refractive index of the incident medium, N s is the complex refractive index of the output medium, N j is the complex refractive index of the j-th layer of medium.

[0065] Complex refractive index N of each layer j Take the following form:

[0066] N j =n j -ik j

[0067] Where n j is the real refractive index, kj is the extinction coefficient.

[0068] k j Reflects the absorption of each layer, k j = 0 means no absorption. Therefore, for a multilayer structure composed of k layers of material, when light is incident from the incident medium N0 at an angle θ0, the characteristic matrix of the combination of the substrate and each layer can be made into

[0069]

[0070]

[0071]

[0072] Further we can get:

[0073]

[0074] Y is called the optical admittance of the combination of each layer and the substrate. The amplitude reflection coefficient r and reflectivity R of the multilayer structure can be calculated from the optical admittance, which are

[0075]

[0076]

[0077] In the formula, * indicates conjugation.

[0078] The above theoretical model can be used to obtain simulation results of the scattering spectrum characteristics of solar cells, which can be combined with the experimental measurement results of the scattering spectrum to analyze the scattering spectrum characteristics of laser-irradiated cells.

[0079] In some specific embodiments of the present invention, the step of calculating theoretical scattering spectrum data of a solar cell according to the specified thicknesses of the GaInP layer and the GaAs layer includes:

[0080] Step S210: Calculate the complex refractive index N of each layer of the solar cell according to the incident angle θ0 and the geometric thickness of each layer of the solar cell. j and the incident angle θ of the jth layer j , the calculation formula is:

[0081] N j =n j -ik j ,

[0082]

[0083] Among them, the solar cell has N layers, j = 1, 2, ..., N, N0 is the complex refractive index of the medium in vacuum or atmospheric environment, θ0 is the incident angle of the incident light on the first layer of the solar cell, nj is the real refractive index of the jth layer of the solar cell, k j is the extinction coefficient of the jth layer of the solar cell, and i is an imaginary unit;

[0084] Since in a vacuum or atmospheric environment, the complex refractive index N0 of the medium can be approximately 1, and determines the complex refractive index N of each layer j The two parameters with specific values ​​are the real refractive index n of the medium j and the extinction coefficient k of the medium j , after the type of each layer is determined, it is only related to the wavelength of the incident light. Therefore, after the incident angle θ0 is determined, the complex refractive index N j and the incident angle θ of the jth layer j calculate.

[0085] Step S220: Calculate the effective phase thickness δ of the jth layer j , the calculation formula is:

[0086]

[0087] Among them, d j is the thickness of the jth layer of the solar cell, and λ is the wavelength of the incident light;

[0088] Step S230: Calculate the admittance η of the jth layer j , the calculation formula is:

[0089]

[0090] Step S240: Calculate the spectral reflectance R total (θ i ,λ), the parameters required for calculation are the effective phase thickness δ j and admittance η j , since the change of optical properties also depends on the polarization state of light, when the incident light is unpolarized, according to the Fresnel equation, the total spectral reflectance is:

[0091]

[0092] Among them, R S (θ i ,λ) and R P (θ i ,λ) represent the spectral reflectance of S-polarized wave and P-polarized wave respectively. j Substitute the following spectral reflectance R expression to obtain, where * represents conjugation,

[0093]

[0094]

[0095] When the number of layers L = 4, the above formula can be transformed into:

[0096]

[0097] See also Figure 3 In some specific embodiments of the present invention, in the step of inverting solar cell damage, a measured spectrum curve is obtained based on the measured spectral reflectance data, and a simulated spectrum curve is obtained based on the calculated theoretical scattering spectrum data. The absorption peak characteristics of the measured spectrum curve and the simulated spectrum curve in the visible light band, and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve are compared. If they are consistent, it indicates that the GaInP layer and GaAs layer battery thickness in the specified solar cell is the thickness of the solar cell after damage; if they are not consistent, the GaInP layer and GaAs layer battery thickness are re-specified, and the theoretical scattering spectrum data of the solar cell are calculated using the new GaInP layer and GaAs layer battery thickness, thereby obtaining a new simulated spectrum curve for comparison, until the absorption peak characteristics of the measured spectrum curve and the simulated spectrum curve in the visible light band, and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve are consistent, that is, until the thickness of the solar cell after damage is obtained.

[0098] Example 2

[0099] This embodiment takes a triple-junction gallium arsenide solar cell as an example to further illustrate the solar cell laser damage identification method of the present invention.

[0100] The simplified structure of a triple-junction GaAs solar cell is shown in Figure 2. Figure 4 As shown in the figure, the triple-junction gallium arsenide solar cell mainly includes an anti-reflection film DAR layer, a top cell GaInP layer, a middle cell GaAs layer and a bottom cell Ge layer. The main materials are TiO2 / Al2O3, GaInP, GaAs and Ge respectively. The thickness of each cell layer is as follows: TiO2 / Al2O3 = 0.100μm, GaInP = 0.670μm, GaAs = 3.7μm, Ge = 170μm, and the total thickness of the cell sample is about 174.47μm.

[0101] By changing the thickness of each layer of the solar cell, the present invention simulates and analyzes the influence of each layer of the solar cell on the target scattering characteristics. Taking the typical measurement geometric model 30° as an example, the results are as follows: Figure 5 、 Figure 6 、 Figure 7 shown.

[0102] The effects of the DAR layer and the Ge layer on the spectral reflectivity of the cell are shown in Figure 5 and Figure 6As shown in the figure, the horizontal axis is wavelength, ranging from 400 to 1200nm, and the vertical axis is spectral reflectivity, ranging from 0 to 1. In the absence of the DAR layer and the Ge layer, the amplitude of the battery spectral reflectivity curve increases as a whole. The absorption peak in the visible spectrum (400 to 750nm) and the quasi-periodic oscillation phenomenon in the near-infrared spectrum (900 to 1200nm) still exist, and the trend of the scattering spectrum change does not change significantly. This is mainly because the anti-reflection film DAR layer and the bottom battery Ge layer function to absorb sunlight and reduce reflected energy, which has no effect on the change pattern of the scattering spectrum characteristics.

[0103] The influence of GaInP and GaAs layers on the spectral reflectivity of the cell is as follows Figure 7 As shown, when the cell contains only the GaInP layer, the spectral reflectivity curve exhibits a clear absorption peak in the visible spectrum. However, when the cell contains only the GaAs layer, the spectral reflectivity curve has no absorption peak in the visible spectrum, and the near-infrared curve exhibits periodic oscillation-like thin-film interference characteristics after 900nm. The simulation results show that the top cell GaInP layer primarily affects the absorption peak in the visible spectrum, while the middle cell GaAs layer primarily affects the interference characteristics in the near-infrared spectrum.

[0104] Therefore, the main functions of each layer of cells in a triple-junction GaAs solar cell are as follows:

[0105] (1) Anti-reflection film DAR layer: absorbs sunlight, reduces reflected energy, and has little effect on the changing pattern of the scattering spectrum curve characteristics;

[0106] (2) Top cell GaInP layer: It mainly affects the absorption characteristics of the visible spectrum. When this layer of cell is damaged, the number of absorption peaks in the visible spectrum decreases, the position of the absorption peak shifts, and the amplitude of the absorption peak weakens.

[0107] (3) Middle battery GaAs layer: mainly affects the interference characteristics of the near-infrared spectrum. When this layer of battery is damaged, the periodic oscillation characteristics of the near-infrared spectrum curve gradually disappear;

[0108] (4) Bottom cell Ge layer: absorbs sunlight, reduces reflected energy, and has little effect on the changing pattern of the scattering spectrum curve characteristics.

[0109] like Figure 8As shown in the figure, the thickness variation characteristics of the GaInP layer and GaAs layer caused by the change of laser energy density are given. In the figure, the horizontal axis is the laser energy density, the vertical axis on the left is the thickness of the GaInP layer, and the vertical axis on the right is the thickness of the GaAs layer. Line 1 is the change in the thickness of the GaInP layer, and line 2 is the change in the thickness of the GaAs layer. The changes in the scattering spectrum of the damaged battery after irradiation with different laser energy densities are obtained by simulation analysis and compared with the actual measurement results. If the characteristics of the spectrum curve are consistent, the damage of the solar cell can be judged. As shown in Figure 9, line 1 in the figure is the spectrum measurement curve of the original intact battery, line 2 is the experimental measurement curve of the spectrum of the irradiated damaged battery, and line 3 is the simulation curve of the spectrum of the irradiated damaged battery. Through comparison, it is found that the characteristics of the experimentally measured visible light and near-infrared spectrum curves are basically consistent with the characteristics of the simulated spectrum curves, which verifies the accuracy of the method.

[0110] Example 3

[0111] This embodiment further illustrates the solar cell laser damage identification system of the present invention.

[0112] See also Figure 10 The solar cell laser damage identification system of this embodiment includes a solar cell surface scattering spectrum measurement device, a solar cell theoretical scattering spectrum data calculation module and a solar cell damage inversion module; wherein the solar cell surface scattering spectrum measurement device is used to measure the spectral reflectance data of the solar cell after laser damage, and the solar cell theoretical scattering spectrum data calculation module is used to calculate the theoretical scattering spectrum data of the solar cell according to the specified GaInP layer and GaAs layer cell thickness; the solar cell damage inversion module is used to invert the solar cell damage, and the module inverts the solar cell damage by comparing the absorption peak characteristics of the visible light band and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve based on the measured spectral reflectance data and the calculated theoretical scattering spectrum data.

[0113] In order to obtain the scattering spectrum characteristics of laser damage to solar cells, in some specific embodiments of the present invention, the spectral reflectance data of solar cells after laser damage is obtained by measuring with a ground experimental system, and in other specific embodiments, it is obtained by actually measuring non-cooperative target solar cells.

[0114] This embodiment adopts Figure 11 The solar cell surface scattering spectrum measurement device shown in the figure includes a darkroom, a light source, a detector, a spectrum detection module, a three-dimensional motion platform, and a data acquisition and control module. Among them, the light source, the detector, and the three-dimensional motion platform are placed in the darkroom.

[0115] During measurement, the laser-damaged solar cell is first placed on a three-dimensional motion platform. The data acquisition and control module controls the three-dimensional motion platform to move to the test position. The incident light emitted by the light source irradiates the solar cell, and the solar cell reflects the incident light. The detector receives the reflected light of the solar cell, and the reflected light information is introduced into the spectrometer in the spectrum detection module. After receiving the reflected light information transmitted by the detector, the spectrometer outputs the processed original scattered spectrum information to the data acquisition and control module. There are multiple test positions to ensure that all positions of the solar cell are measured. By processing the original scattered spectrum data measured multiple times, the spectral reflectance data of the solar cell after laser damage is obtained, so as to perform a discrimination analysis on the damage condition of the laser-irradiated solar cell.

[0116] Preferably, the three-dimensional motion platform includes a rotating platform, a first mechanical cantilever and a second mechanical cantilever, the rotating platform is used to fix the solar cell, the light source is arranged on the first mechanical cantilever, and the detector is arranged on the second mechanical cantilever; the data sampling and control module controls the position of the rotating platform, the first mechanical cantilever and the second mechanical cantilever, thereby controlling the azimuth rotation of the solar cell and / or measuring the change of the geometric model.

[0117] Preferably, in a specific embodiment of the present invention, the detector utilizes a flux detector with two transmission channels: a visible channel and an infrared channel. The detector receives reflected light scattered from the target. During spectral measurement, the detector can perform circular motion around the sample rotating platform, enabling detection within a 0° to 360° range. Target measurement and data acquisition and processing are both automatically performed by a computer system.

[0118] Preferably, the darkroom is fully enclosed, and no other stray light enters the darkroom. The instruments and walls are coated with matte paint, so that the reflectivity of the wall and the instrument is less than 3%. The darkroom can eliminate stray light and absorb background light to a high degree, thereby ensuring the measurement accuracy of the experimental system.

[0119] Preferably, the light source includes a halogen lamp, a focusing bowl, an aperture, and a power supply. An adjustable power supply supplies power to the halogen lamp to regulate the lamp current, while the focusing bowl focuses the light emitted by the halogen lamp into parallel light. The halogen lamp is located on a mechanical cantilever that moves on a three-dimensional motion platform, and the center of the parallel light coincides with the center of the solar cell placed on the rotating platform. The aperture limits the spot size of the incident light source, ensuring that the light source fully illuminates the sample surface and reducing interference with the detector's optical information during measurement caused by reflected light from the platform or gasket.

[0120] Halogen lamps offer 10% higher lighting efficiency than standard lamps. Filled with xenon, they feature dimmable light and a spectral range of 400 to 1700 nm. Driven by an adjustable, regulated current power supply, they offer excellent operational stability. To address shading and heat dissipation, the light source system incorporates components such as a fan and a shading tube with fins to filter out stray light and dissipate heat naturally.

[0121] Preferably, the three-dimensional motion platform controls the movement of the instrument through a computer, and the battery sample is placed horizontally on the rotating platform. Since the optical information received by the detector is related to multiple factors such as the incident angle and azimuth of the light source and the receiving angle, receiving azimuth, and wavelength of the detector, in order to simplify the measurement geometric model, the light source and the detector are constrained in the same plane. At this time, the measurement geometric model of the scattering spectrum is only related to the incident angle of the light source, the receiving angle of the detector, the wavelength, and the relative intensity of the spectrum.

[0122] Preferably, the spectrometer includes two spectrometers with different spectral response ranges, which can obtain spectral information from visible light to near-infrared light. Since solids do not have molecular rotation in the usual sense, they cannot form far-infrared spectra. The near-infrared spectrum is a vibrational spectrum generated by molecular vibrational energy level transitions. When a substance produces a visible light spectrum, it will also produce a near-infrared spectrum. Therefore, the experiment selected spectra in the visible light and near-infrared spectral ranges (400-1200nm) to analyze the surface scattering spectral characteristics of solar cells before and after irradiation.

[0123] Preferably, the data acquisition and control module is mainly composed of a spectrometer, platform driving software and a control system, which realizes continuous acquisition of spectra.

[0124] The present invention discloses a method and system for identifying laser damage to solar cells. The present invention first obtains spectral reflectance data of a solar cell after laser damage, obtained through measurement, and calculates theoretical scattering spectrum data of the solar cell based on the specified cell thicknesses of the GaInP layer and GaAs layer. Finally, based on the measured spectral reflectance data and the calculated theoretical scattering spectrum data, the solar cell damage is inverted by comparing the absorption peak characteristics of the visible light band and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve. The method and system of the present invention utilize the surface material properties and wavelength dimension resolution information provided by the scattering spectrum to reflect the material, and achieve damage identification of the solar cell by measuring the scattering spectrum of the solar cell before and after laser irradiation. The solution of the present invention is simple to implement and easy to implement in engineering and experimentally verify.

[0125] This application is not limited to the contents defined in the description and claims. Any modifications and changes known in the art fall within the scope of this application. The specific embodiments of the description are only illustrative of the present invention and are not specific limitations of the present invention.

Claims

1. A method for identifying laser damage to solar cells, characterized in that include: Step S10: obtaining spectral reflectance data of the solar cell after laser damage obtained by measurement; Step S20: Calculating theoretical scattering spectrum data of the solar cell according to the specified GaInP layer and GaAs layer cell thicknesses; Step S210: According to the incident angle and the geometric thickness of each layer of the solar cell, calculate the complex refractive index of each layer of the solar cell Pass the exam j Layer incident angle , the calculation formula is: ， ， Among them, solar cells have k layer, j Indicates the first j Layer space, , is the complex refractive index of the medium in vacuum or atmospheric environment, is the incident angle of the incident light on the outside of the first layer of the solar cell, For solar cells j The real refractive index of the layer, For solar cells j The extinction coefficient of the layer, i is an imaginary unit; Step S220: Calculate the j Effective phase thickness of the layer , the calculation formula is: in, For solar cells j The thickness of the layer, λ is the wavelength of the incident light; Step S230: Calculate the j Admittance of the layer , the calculation formula is: Step S240: Calculate spectral reflectance , the calculation formula is: ， in, and Represent the spectral reflectance of S-polarized wave and P-polarized wave respectively, by taking the admittance Substitute the following spectral reflectance The expression is obtained, where * means taking conjugate, in, is the admittance in vacuum or atmospheric environment; Step S30: Inverting solar cell damage. In this step, the solar cell damage is inverted by comparing the absorption peak characteristics of the visible light band and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve based on the measured spectral reflectance data and the calculated theoretical scattering spectrum data. A measured spectrum curve is obtained based on the spectral reflectance data obtained by measurement, and a simulated spectrum curve is obtained based on the theoretical scattering spectrum data obtained by calculation. The absorption peak characteristics of the visible light band and the quasi-periodic oscillation characteristics of the measured spectrum curve and the simulated spectrum curve are compared. If they are consistent, it indicates that the battery thickness of the GaInP layer and GaAs layer in the specified solar cell is the thickness of the solar cell after damage; if they are not consistent, the battery thickness of the GaInP layer and GaAs layer is re-specified, and the theoretical scattering spectrum data of the solar cell is calculated using the new GaInP layer and GaAs layer battery thickness, so as to obtain a new simulated spectrum curve for comparison, until the absorption peak characteristics of the visible light band and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve of the measured spectrum curve and the simulated spectrum curve are consistent, that is, until the thickness of the solar cell after damage is obtained.

2. A system for implementing the solar cell laser damage identification method according to claim 1, characterized in that: It includes a solar cell surface scattering spectrum measurement device, a solar cell theoretical scattering spectrum data calculation module and a solar cell damage inversion module; wherein, The solar cell surface scattering spectrum measurement device is used to measure the spectral reflectance data of solar cells after laser damage. The solar cell theoretical scattering spectrum data calculation module is used to calculate the theoretical scattering spectrum data of the solar cell according to the specified GaInP layer and GaAs layer cell thickness; The solar cell damage inversion module is used to invert solar cell damage. The module inverts the solar cell damage based on the measured spectral reflectance data and the calculated theoretical scattering spectrum data by comparing the absorption peak characteristics of the visible light band and the quasi-periodic oscillation characteristics of the near-infrared spectrum curve.

3. The solar cell laser damage identification system according to claim 2, characterized in that: The solar cell surface scattering spectrum measurement device is an experimental measurement device, which includes a darkroom, a light source, a detector, a spectrum detection module, a three-dimensional motion platform, and a data acquisition and control module; wherein the light source, the detector and the three-dimensional motion platform are placed in the darkroom; During measurement, the laser-damaged solar cell is first placed on a three-dimensional motion platform. The data acquisition and control module controls the three-dimensional motion platform to move to the test position. The incident light emitted by the light source irradiates the solar cell, and the solar cell reflects the incident light. The detector receives the reflected light from the solar cell, and the reflected light information is introduced into the spectrometer in the spectrum detection module. After receiving the reflected light information transmitted by the detector, the spectrometer outputs the processed original scattered spectrum information to the data acquisition and control module. There are multiple test positions to ensure that all positions of the solar cell are measured. By processing the original scattered spectrum data measured multiple times, the spectral reflectance data of the solar cell after laser damage is obtained.

4. The solar cell laser damage identification system according to claim 3, characterized in that: The three-dimensional motion platform includes a rotating platform, a first mechanical cantilever, and a second mechanical cantilever. The rotating platform is used to fix the solar cell. The light source is set on the first mechanical cantilever, and the detector is set on the second mechanical cantilever. The data sampling and control module controls the position of the rotating platform, the first mechanical cantilever, and the second mechanical cantilever, thereby controlling the azimuth rotation of the solar cell and / or measuring the change of the geometric model.

5. The solar cell laser damage identification system according to claim 4, characterized in that: The first mechanical cantilever and the second mechanical cantilever constrain the light source and the detector in the same plane. The first mechanical cantilever and the second mechanical cantilever enable the detector to perform circular motion around the sample rotating platform, thereby receiving reflected light in the range of 0° to 360°.

6. The solar cell laser damage identification system according to claim 5, characterized in that: The detector adopts a light flux detector, whose transmission channel includes a visible light channel and a near-infrared channel. The reflected light scattered by the solar cell under test is received by the detector. Correspondingly, the spectrometer includes a visible light spectrometer and a near-infrared spectrometer, which are connected to the visible light channel and the near-infrared channel respectively.

7. The solar cell laser damage identification system according to claim 5, characterized in that: The light source includes a halogen lamp, a focusing bowl, an aperture and a power supply; the power supply supplies power to the halogen lamp and realizes current regulation of the halogen lamp; the focusing bowl focuses the light emitted by the halogen lamp into parallel light, which serves as incident light to illuminate the solar cell; the halogen lamp is located on the robotic arm of the three-dimensional motion platform, and the center position of the incident light coincides with the center of the solar cell placed on the three-dimensional motion platform; the aperture is used to limit the spot size of the incident light so that the incident light can completely illuminate the surface of the sample.

8. The solar cell laser damage identification system according to claim 5, characterized in that: The darkroom is of fully enclosed design, and no other stray light enters the darkroom. The light source, detector, three-dimensional motion platform and walls placed in the darkroom are coated with matte paint.

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