Engineering calculation method and device for back irradiance of high-precision double-sided photovoltaic module

Abstract

The invention discloses an engineering calculation method and device for back irradiance of a high-precision double-sided photovoltaic module. The calculation method comprises the following steps: (1) inputting related parameter information of a photovoltaic power station; (2) the array is simplified into a two-dimensional diagram, and the sun position including the zenith angle and the azimuth angle is calculated; (3) calculating the ground shadow condition according to the geometric information of the component and the sun position; (4) calculating a sky view angle factor between rows which can be seen by each ground section according to the geometric parameters of the array; calculating an incident angle according to the dip angle, the component azimuth, the solar azimuth and the zenith angle; using a Perez model to decompose the input horizontal direct radiation irradiance and horizontal diffusion irradiance into a direct radiation part, an isotropic diffusion part, an annular solar region diffusion part, a horizon line scattering part and a ground reflection part; using a Perez model to calculate the diffused irradiance of the inclined plane; and (5) calculating the back irradiance after all the steps are completed. According to the method, a three-dimensional scene is simplified into a two-dimensional scene, a View Factor method, back shadow analysis and a sky view angle factor algorithm are simplified, the irradiance received by the ground is accurately considered, and the irradiance received by the back is calculated by using angle-by-angle incidence loss, so that the accuracy is not lacked, and the operation efficiency is high.

Description

Technical Field

[0001] The invention relates to a high-precision engineering calculation method and device for the back irradiance of a double-sided photovoltaic module, and belongs to the field of photovoltaics. Background Art

[0002] In the photovoltaic field, bifacial photovoltaic modules have attracted widespread attention and application in recent years due to their ability to simultaneously absorb sunlight from both the front and back sides, thereby improving power generation efficiency. To accurately evaluate the power generation performance of bifacial photovoltaic modules, it is crucial to understand the distribution of irradiance on the back side.

[0003] Currently, the View Factor method is the basis for calculating the backside irradiance of bifacial photovoltaic modules. Based on geometry and the principles of radiation heat transfer, the View Factor method describes the proportion of radiant energy received by one surface from another. In calculating the backside irradiance of bifacial photovoltaic modules, the View Factor method is used to calculate the scattered and reflected irradiance received by the module's backside from the surrounding environment.

[0004] However, while the View Factor method is the basis for calculating the backside irradiance of bifacial photovoltaic modules, in practice, different researchers and institutions may adopt different simplification schemes. These simplification schemes may vary in terms of calculation accuracy, efficiency, and scope of application, leading to inconsistent calculation results.

[0005] Furthermore, most current calculation methods do not perform cell-by-cell irradiance simulation. Bifacial PV modules typically consist of multiple cells, and the irradiance received by each cell on its back may vary due to factors such as position, angle, and shading. Therefore, to more accurately evaluate the power generation performance of bifacial PV modules, cell-by-cell irradiance simulation is necessary. This calculation method requires more complex mathematical models and higher computing power, but it can provide more accurate and detailed results.

[0006] In summary, the current method for calculating the backside irradiance of bifacial PV modules primarily uses the View Factor method. However, the inconsistency of simplified schemes and the lack of cell-by-cell simulation limit its accuracy and applicability. Therefore, further refinement and optimization of the calculation method are needed to improve the accuracy of evaluating the power generation performance of bifacial PV modules. Summary of the Invention

[0007] In order to solve the above problems, the present invention provides a high-precision engineering calculation method and device for the back side irradiance of bifacial photovoltaic modules. The method is based on the View Factor method and is simplified. The irradiance of the irradiance source is simulated by analyzing the ground shadow conditions, etc. The View Factor method is used to calculate the irradiance transfer fraction between the two surfaces for each cell, thereby realizing irradiance analysis at the cell level.

[0008] The technical solutions of the present invention are as follows:

[0009] A high-precision engineering calculation method for the back irradiance of a bifacial photovoltaic module includes the following steps:

[0010] (1) Input relevant parameter information of the photovoltaic power station;

[0011] (2) Simplify the array into a two-dimensional diagram, ignoring the factors in the length direction of the array and only considering the factors in the height direction of the array; calculate the sun's position, including the zenith angle and azimuth angle;

[0012] Simplify the View Factor method to two dimensions: Where θ1<θ2;

[0013] (3) Calculate the ground shadow situation based on the component geometry information and the sun position;

[0014] (4) Calculate the sky viewing angle factor between rows that can be seen by each ground segment based on the array geometric parameters; calculate the incident angle based on the inclination angle, component azimuth angle, solar azimuth angle, and zenith angle; use the Perez model to decompose the input horizontal direct irradiance and horizontal diffuse irradiance into direct, isotropic diffuse, circumsolar diffuse part, horizon scattered part, and ground reflected part; use the Perez model to calculate the inclined surface diffuse irradiance;

[0015] (5) After all the above steps are completed, calculate the back irradiance. The back irradiance amplitude is divided into four parts: direct sky, sky scattering, front surface reflection, and ground reflection. Decompose the back of the component into 180 1-degree segments to solve;

[0016] Since the model calculates irradiance by angle segments, the AOI correction of the one-degree segment considering diffuse radiation is a fixed value of 180;

[0017] The back diffuse irradiance is obtained by dividing the back surface into 180 one-degree segments and adding the product of view factor, AOI correction and irradiance to each segment;

[0018]

[0019] Where VF i is the viewing factor of the i-th degree segment, Fi is the AOI correction coefficient of the i-th segment, I i is the source irradiance of the i-th segment; B glo is the total radiation received by the back side, B dir is the amount of direct radiation received by the back surface.

[0020] The information of the photovoltaic power station in the above step (1) includes the module model, tilt angle, photovoltaic module width in the array height direction, azimuth angle, ground reflectivity, spacing, height of the lowest point of the module from the ground, local latitude and longitude, and meteorological data.

[0021] The specific calculation steps of the above step (3) are as follows:

[0022] Given the width of the module W, we can get the height of the photovoltaic panel h = W·sin(β), where h represents the vertical distance from the highest point of the module to the lowest point of the module. Given the module azimuth and the solar azimuth and zenith angle obtained in step (2), we can get Where sazm represents the module azimuth, azm represents the solar azimuth, zen represents the solar zenith angle, and PA represents the horizontal angle between the highest point of the module and the endpoint of the corresponding shadow part;

[0023] The shadow position is determined by three lengths:

[0024] Lh represents the horizontal distance between the intersection of the highest point of the component and the right side of the horizontal shadow of the lowest point of the component;

[0025] Lhc represents the horizontal distance between the highest point of the component and the shadow on the right side of the ground;

[0026] Lc represents the horizontal distance between the lowest point of the component and the shadow on the left side of the ground;

[0027] C represents the distance between the component and the ground;

[0028] If D<Lh<-(2·pitch-D), the ground is completely shaded. In other cases, the shadow range is determined based on Lc and Lhc in (0, pitch). The ground is divided into 100 segments, and each segment is judged to be within the shadow range. The proportion of the back shadow is also calculated. i,back , D represents the horizontal distance between the highest point of the component and the lowest point of the back row component; pitch represents the distance between the two components.

[0029] The calculation steps of the sky view factor in step (4) above are as follows:

[0030] The single-line viewing factor is Among them, β1 is the largest angle formed by the highest point and the lowest point of the components at the back of the row and the ground segment, and β2 is the smallest angle formed by the highest point and the lowest point of the components at the front of the row and the ground segment. The sky view factor of the ground segment is obtained by adding up all the view factors of the front, middle and back rows.

[0031] The calculation formula for the incident angle in step (4) above is as follows:

[0032] angle=arccos(sin(zen)·cos(azm-sazm)·sinβ+cos(zen)·cosβ);

[0033] Where β represents the module inclination angle, sazm represents the module azimuth angle, azm represents the solar azimuth angle, and zen represents the solar zenith angle.

[0034] The calculation formula for the diffuse irradiance of the inclined surface in step (4) above is as follows:

[0035]

[0036] The diffuse part includes isotropic diffuse, circumsolar diffuse and horizontal diffuse;

[0037] Where F1 and F2 are the annular coefficient and horizontal brightness coefficient, which are functions describing the three parameters of zenith angle, clarity and brightness; β is the component inclination angle, a is the cosine of the incident angle, and b is the cosine of the zenith angle.

[0038] The irradiance calculation formula of the sky scattered part in the back irradiance amplitude in the above step (5) is as follows:

[0039] Sky scattering part: multiply the View factor by the horizontal diffuse irradiance, as shown in formula B i,dif =VF(0,β i,sky )·H dif , where β i,sky is the end angle of the sky part, the starting angle of the sky part is 0°, H dif is the horizontal diffuse irradiance.

[0040] The irradiance of the front surface reflected part of the back surface irradiance amplitude in the above step (5) is calculated as follows:

[0041] What needs to be considered is the effective diffuse irradiance reflected from the front surface of the array to the rear of the module. In this process, it is assumed that direct light and diffuse light around the sun are specular reflections and will not reach the back of the module, so the direct light reflected from the front is ignored.

[0042] In the formula is the diffuse irradiance of the inclined surface, IAMdif is the incident angle correction factor of diffuse irradiance, R cor is the incident angle correction factor, assuming the reflective surface is glass and the incident angle is 60°, and L is the contamination loss;

[0043] The calculation formula for the portion of light reflected from the front surface that reaches the back surface is:

[0044] Where β i,sky The sky part ends at an angle of 0°, and the sky part starts at an angle of 0°. i,ground is the starting angle of the ground part, and the ending angle of the ground part is 180°.

[0045] The irradiance calculation method for the ground reflection part of the back irradiance amplitude in the above step (5) is as follows:

[0046] First calculate the irradiance received by the ground. According to the obtained ground shadow and sky viewing factor, the irradiance GRI received by the ground is n For GRI n =α·(DNI+I cir )+CF sky I sky , where α is the cosine of the solar zenith angle if the ground segment is not blocked, DNI is the direct normal irradiance, and the input is the horizontal direct irradiance. The conversion formula is HDir=DNI·cos(zenith), CF sky is the sky viewing factor, I sky is the isotropic sky diffuse irradiance;

[0047] From β i,ground Each 1° segment (j, j+1) from 180° to 180° is projected onto the ground, and the view factor of the segment is calculated separately. The ground irradiance (actualGroundGHI) of the segment (j, j+1) is j ) is obtained by using the range of the projection on the ground as an index. It is assumed that all ground areas between rows have the same irradiance distribution. Therefore, regardless of whether the projection is inside or outside the row, the ground irradiance can be obtained by limiting the index value to the index of the current row. If the projection range exceeds the row spacing, the average irradiance will be used.

[0048]

[0049] Where β i,ground is the starting angle of the ground part, actualGroundGHI j is the ground irradiance of segment (j, j+1), proj x1 is the starting position of (j, j+1) projected on the ground, proj x2is the end position of the projection of (j, j+1) on the ground, and albedo is the albedo of the ground;

[0050] The irradiance calculation formula of the direct sky portion in the back irradiation amplitude in step (5) is as follows:

[0051] B i,dir =T dir ·(1-Shade i,back ), where T dir is the direct irradiance of the inclined surface, Shade i,back is the backface occlusion score.

[0052] A device, which utilizes the above-mentioned calculation method, is used to perform high-precision calculation of the simulation accuracy and efficiency of the back irradiance of a bifacial photovoltaic module.

[0053] The beneficial effects of the present invention are:

[0054] This method simplifies the three-dimensional scene into two dimensions, and simplifies the View Factor method, back shadow analysis, sky view factor algorithm, accurately considers the irradiance received by the ground, and uses the angle-by-angle incidence loss to calculate the irradiance received by the back. It has both high accuracy and high efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is the geometric information of photovoltaic modules and the position of the sun;

[0056] Figure 2 It is a schematic diagram of the sky view factor between rows that can be seen by each ground segment;

[0057] Figure 3 is a schematic diagram of the irradiance of the scattered part of the sky;

[0058] Figure 4 It is a schematic diagram of the irradiance of the ground reflection part;

[0059] Figure 5 This is a comparative data diagram of Example 1. DETAILED DESCRIPTION

[0060] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0061] A high-precision engineering calculation method for the back irradiance of a bifacial photovoltaic module includes the following steps:

[0062] (1) Input relevant parameter information of the photovoltaic power station;

[0063] (2) Simplify the array into a two-dimensional diagram, ignoring the factors in the length direction of the array and only considering the factors in the height direction of the array; calculate the sun's position, including the zenith angle and azimuth angle;

[0064] Simplify the View Factor method to two dimensions: Where θ1<θ2;

[0065] (3) Calculate the ground shadow situation based on the component geometry information and the sun position;

[0066] (4) Calculate the sky viewing angle factor between rows that can be seen by each ground segment based on the array geometric parameters; calculate the incident angle based on the inclination angle, component azimuth angle, solar azimuth angle, and zenith angle; use the Perez model to decompose the input horizontal direct irradiance and horizontal diffuse irradiance into direct, isotropic diffuse, circumsolar diffuse part, horizon scattered part, and ground reflected part; use the Perez model to calculate the inclined surface diffuse irradiance;

[0067] (5) After all the above steps are completed, calculate the back irradiance. The back irradiance amplitude is divided into four parts: direct sky, sky scattering, front surface reflection, and ground reflection. Decompose the back of the component into 180 1-degree segments to solve;

[0068] Because the model calculates irradiance by angular segment, the AOI correction for each one-degree segment of diffuse radiation is a fixed value of 180. This method considers the angle distribution of diffuse radiation incident on the PV module and calculates the corresponding AOI correction factor accordingly. Most diffuse radiation is always incident non-perpendicular to the module, so the correction factor is less than 1, which also means that the PV module does not perfectly receive all incident scattered light.

[0069] The back diffuse irradiance is obtained by dividing the back surface into 180 one-degree segments and adding the product of view factor, AOI correction and irradiance to each segment;

[0070]

[0071] Where VF i is the viewing factor of the i-th degree segment, F i is the AOI correction coefficient of the i-th segment, I i is the source irradiance of the i-th segment; B glo is the total radiation received by the back side, B dir is the amount of direct radiation received by the back surface.

[0072] The information of the photovoltaic power station in the above step (1) includes the module model, tilt angle, photovoltaic module width in the array height direction, azimuth angle, ground reflectivity, spacing, height of the lowest point of the module from the ground, local latitude and longitude, and meteorological data.

[0073] The specific calculation steps of the above step (3) are as follows:

[0074] like Figure 1 As shown, given the width of the module W, the height of the photovoltaic panel is obtained as h = W·sin(β), where h represents the vertical distance from the highest point of the module to the lowest point of the module. Given the module azimuth and the solar azimuth and zenith angle obtained in step (2), we can get Where sazm represents the module azimuth, azm represents the solar azimuth, zen represents the solar zenith angle, and PA represents the horizontal angle between the highest point of the module and the endpoint of the corresponding shadow part;

[0075] The shadow position is determined by three lengths:

[0076] Lh represents the horizontal distance between the intersection of the highest point of the component and the right side of the horizontal shadow of the lowest point of the component;

[0077] Lhc represents the horizontal distance between the highest point of the component and the shadow on the right side of the ground;

[0078] Lc represents the horizontal distance between the lowest point of the component and the shadow on the left side of the ground;

[0079] C represents the distance between the component and the ground;

[0080] If D<Lh<-(2·pitch-D), the ground is completely shaded. In other cases, the shadow range is determined based on Lc and Lhc in (0, pitch). The ground is divided into 100 segments, and each segment is judged to be within the shadow range. The proportion of the back shadow is also calculated. i,back , D represents the horizontal distance between the highest point of the component and the lowest point of the back row component; pitch represents the distance between the two components.

[0081] The calculation steps of the sky view factor in step (4) above are as follows:

[0082] like Figure 2 As shown, the sum of the view factors of all the front, middle and back rows is the sky view factor of the ground segment. The view factor of a single row is Among them, β1 is the largest angle formed by the highest point and the lowest point of the components at the back of the row and the ground segment, and β2 is the smallest angle formed by the highest point and the lowest point of the components at the front of the row and the ground segment. The sky view factor of the ground segment is obtained by adding up all the view factors of the front, middle and back rows.

[0083] The calculation formula for the incident angle in step (4) above is as follows:

[0084] angle=arccos(sin(zen)·cos(azm-sazm)·sinβ+cos(zen)·cosβ);

[0085] Where β represents the module inclination angle, sazm represents the module azimuth angle, azm represents the solar azimuth angle, and zen represents the solar zenith angle.

[0086] The calculation formula for the diffuse irradiance of the inclined surface in step (4) above is as follows:

[0087]

[0088] The diffuse part includes isotropic diffuse, circumsolar diffuse and horizontal diffuse;

[0089] Where F1 and F2 are the annular coefficient and horizontal brightness coefficient, which are functions describing the three parameters of zenith angle, clarity and brightness; β is the component inclination angle, a is the cosine of the incident angle, and b is the cosine of the zenith angle.

[0090] The irradiance calculation formula of the sky scattered part in the back irradiance amplitude in the above step (5) is as follows:

[0091] The component back is decomposed into 180 1-degree segments to solve.

[0092] Sky scattering part: multiply the View factor by the horizontal diffuse irradiance, as shown in formula B i,dif =VF(0,β i,sky )·H dif , where β i,sky is the end angle of the sky part, and the starting angle of the sky part is 0°, such as Figure 3 As shown, H dif is the horizontal diffuse irradiance.

[0093] The irradiance of the front surface reflected part of the back surface irradiance amplitude in the above step (5) is calculated as follows:

[0094] What needs to be considered is the effective diffuse irradiance reflected from the front surface of the array to the rear of the module. In this process, it is assumed that direct light and diffuse light around the sun are specular reflections and will not reach the back of the module, so the direct light reflected from the front is ignored.

[0095] Where T difref is the diffuse irradiance of the inclined surface, IAM dif is the incident angle correction factor of diffuse irradiance, R cor is the incident angle correction factor, assuming the reflective surface is glass and the incident angle is 60°, and L is the contamination loss;

[0096] The calculation formula for the portion of light reflected from the front surface that reaches the back surface is:

[0097] Where β i,sky The sky part ends at an angle of 0°, and the sky part starts at an angle of 0°. i,ground is the starting angle of the ground part, and the ending angle of the ground part is 180°.

[0098] The irradiance calculation method for the ground reflection part of the back irradiance amplitude in the above step (5) is as follows:

[0099] First calculate the irradiance received by the ground. According to the obtained ground shadow and sky viewing factor, the irradiance GRI received by the ground is n For GRI n =α·(DNI+I cir )+CF sky I sky , where α is the cosine of the solar zenith angle if the ground segment is not blocked, DNI is the direct normal irradiance, and the input is the horizontal direct irradiance. The conversion formula is HDir=DNI·cos(zenith), CF sky is the sky viewing factor, I sky is the isotropic sky diffuse irradiance (obtained by decomposing the light using the Perez model);

[0100] From β i,ground Each 1° segment (j, j+1) to 180° is projected onto the ground, such as Figure 4 As shown, the view factor of the segment is calculated separately, and the ground irradiance (actualGroundGHI j ) is obtained by using the range of the projection on the ground as an index. It is assumed that all ground areas between rows have the same irradiance distribution. Therefore, regardless of whether the projection is inside or outside the row, the ground irradiance can be obtained by limiting the index value to the index of the current row. If the projection range exceeds the row spacing,

[0101] The average irradiance will be used to calculate:

[0102]

[0103] Where β i,ground is the starting angle of the ground part, actualGroundGHI j is the ground irradiance of segment (j, j+1), proj x1 is the starting position of (j, j+1) projected on the ground, proj x2 is the end position of the projection of (j, j+1) on the ground, and albedo is the albedo of the ground;

[0104] The irradiance calculation formula of the direct sky portion in the back irradiation amplitude in step (5) is as follows:

[0105] B i,dir =T dir ·(1-Shade i,back ), where T dir is the direct irradiance of the inclined surface, Shade i,back is the backface occlusion score.

[0106] A device, which utilizes the above-mentioned calculation method, is used to perform high-precision calculation of the simulation accuracy and efficiency of the back irradiance of a bifacial photovoltaic module.

[0107] Example 1:

[0108] The irradiance calculations were compared using the mainstream software PVsyst model, SAM model and this model.

[0109] like Figure 5 The figure shows a comparison of the irradiance received by the backside of the satellite using this model, PVsyst, and SAM throughout the year. The default array parameters are: a location in Shanghai, facing due south, a system array collector width of 1.102 meters, a GCR (Gross Response Rate) of 0.5 (the spacing divided by the array collector width), a ground clearance of 0.8 meters, an albedo of 0.3, and an inclination of 25°. Hourly meteorological data are from NREL / NSRDB TMY. This comparison is performed using a controlled variable approach.

[0110] PVsyst's backside irradiance calculation method is relatively accurate under normal configuration and is widely recognized. However, when the array spacing is large, the irradiance increases too much. Figure 5 As shown in the figure, when GCR = 0.01, it is found that the PVsyst irradiance increases too much. In addition, a PVsyst simulation takes a long time, which does not meet the requirement of high efficiency.

[0111] As the array spacing increases, the irradiance on the back of bifacial modules increases. This is because increasing the spacing reduces shadowing between the front and rear rows of modules, allowing more ground-reflected light to reach the back of the modules. However, this increase is not infinite. When the spacing increases to a certain level, the increase in back irradiance gradually reaches saturation. Therefore, PVsyst software has the drawback of discreteness, and irradiance is inaccurate in extreme cases.

[0112] The software SAM does not produce discretization and runs faster, but it may overestimate compared to other models.

[0113] The results of this model are very close to those of PVsyst under normal configuration, and there is no SAM overestimation. In extreme cases, it also shows more reasonable prediction results, demonstrating high accuracy and robustness.

[0114] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-precision engineering calculation method for the back irradiance of a bifacial photovoltaic module, characterized in that The steps include: (1) Input relevant parameter information of the photovoltaic power station; (2) Simplify the array into a two-dimensional diagram, ignoring the factors in the length direction of the array and only considering the factors in the height direction of the array; calculate the sun's position, including the zenith angle and azimuth angle; Simplify the View Factor method to two dimensions: Where θ1<θ2; (3) Calculate the ground shadow situation based on the component geometry information and the sun position; (4) According to the array geometry parameters, calculate the sky viewing factor between rows that can be seen by each ground segment; calculate the angle of incidence according to the inclination angle, component azimuth angle, solar azimuth angle, and zenith angle; use the Perez model to decompose the input horizontal direct irradiance and horizontal diffuse irradiance into direct, isotropic diffuse, circumsolar diffuse, horizon scattered, and ground reflected; use the Perez model to calculate the diffuse irradiance of the inclined surface; (5) After all the above steps are completed, calculate the back irradiance. The back irradiance amplitude is divided into four parts: direct sky, sky scattering, front surface reflection, and ground reflection. Decompose the back of the component into 180 1-degree segments for solution; Since the model calculates irradiance by angle segment, the AOI correction of the one-degree segment considering diffuse radiation is a fixed value of 180; The back diffuse irradiance is calculated by dividing the back surface into 180 one-degree segments and adding the product of the view factor, AOI correction and irradiance to each segment; Where VF i is the viewing factor of the i-th degree segment, F i is the AOI correction coefficient for the i-th segment, I i is the source irradiance in the i-th segment; B glo is the total radiation received by the back side, B dir is the amount of direct radiation received by the back side.

2. A high-precision engineering calculation method for back irradiance of a bifacial photovoltaic module according to claim 1, characterized in that The information of the photovoltaic power station in step (1) includes module model, inclination, photovoltaic module width in the array height direction, azimuth, ground reflectivity, spacing, height of the lowest point of the module from the ground, local longitude and latitude, and meteorological data.

3. A high-precision engineering calculation method for back irradiance of a bifacial photovoltaic module according to claim 1, characterized in that The specific calculation steps of step (3) are as follows: Given the width of the module W, we can get the height of the photovoltaic panel h = W·sin(β), where h represents the vertical distance from the highest point of the module to the lowest point of the module. Given the module azimuth and the solar azimuth and zenith angle obtained in step (2), we can get Where sazm represents the component azimuth, azm represents the solar azimuth, zen represents the solar zenith angle, and PA represents the horizontal angle between the highest point of the component and the endpoint of the corresponding shadow part; The shadow position is determined by three lengths: Lh represents the horizontal distance between the intersection of the highest point of the component and the right side of the shadow of the lowest point of the component in the horizontal direction; Lhc represents the horizontal distance between the highest point of the component and the shadow on the right side of the ground; Lc represents the horizontal distance between the lowest point of the component and the left shadow of the ground; C represents the distance between the component and the ground; If D<Lh<-(2·pitch-D), the ground is completely shadowed. In other cases, the shadow range is determined according to Lc and Lhc in (0, pitch). The ground is divided into 100 segments, and each segment is judged whether it is in the shadow range, and the proportion of the back shadow is solved. i,back , D represents the horizontal distance between the highest point of a component and the lowest point of the back row component; pitch represents the spacing between two components.

4. A high-precision engineering calculation method for back irradiance of a bifacial photovoltaic module according to claim 1, characterized in that The calculation steps of the sky viewing factor in step (4) are as follows: The single-line viewing factor is Among them, β1 is the largest angle formed by the highest point and the lowest point of the component behind the row and the ground segment, and β2 is the smallest angle formed by the highest point and the lowest point of the component in front of the row and the ground segment. The sum of all the viewing angle factors in the front, middle and back rows is the sky viewing angle factor of the ground segment.

5. A high-precision engineering calculation method for back irradiance of a bifacial photovoltaic module according to claim 1, characterized in that The calculation formula of the incident angle in step (4) is as follows: angle=arccos(sin(zen)·cos(azm-sazm)·sinβ+cos(zen)·cosβ); Where β represents the component inclination angle, sazm represents the component azimuth angle, azm represents the solar azimuth angle, and zen represents the solar zenith angle.

6. A high-precision engineering calculation method for back irradiance of a bifacial photovoltaic module according to claim 1, characterized in that The calculation formula of the inclined surface diffuse irradiance in step (4) is as follows: The diffuse part includes isotropic diffuse, circumsolar diffuse and horizontal diffuse; Among them, F1 and F2 are the annular coefficient and the horizontal brightness coefficient, which are functions describing the three parameters of zenith angle, clarity and brightness; β is the component inclination angle, a is the cosine of the incident angle, and b is the cosine of the zenith angle.

7. A high-precision engineering calculation method for back irradiance of a bifacial photovoltaic module according to claim 1, characterized in that The irradiance calculation formula of the sky scattered part in the back side irradiation amplitude in step (5) is as follows: Sky scattering part: multiply the View factor by the horizontal diffuse irradiance, as shown in formula B i,dif =VF(0,β i,sky )·H dif , where β i,sky is the end angle of the sky part, the starting angle of the sky part is 0°, H dif is the horizontal diffuse irradiance.

8. A high-precision engineering calculation method for back irradiance of a bifacial photovoltaic module according to claim 1, characterized in that The method for calculating the irradiance of the front surface reflected part in the back surface irradiation amplitude in step (5) is as follows: What needs to be considered is the effective diffuse irradiance T reflected from the front surface of the array to the rear of the module. difref In this process, it is assumed that direct light and diffuse light around the sun are specular reflections and will not reach the back of the component, so the direct light reflected from the front is ignored; Where T difref is the diffuse irradiance of the inclined surface, IAM dif is the incident angle correction factor of diffuse irradiance, R cor is the incident angle correction factor, assuming that the reflective surface is glass and the incident angle is 60°, and L is the contamination loss; The calculation formula for the portion of the reflection from the front surface that reaches the back surface is: Where β i,sky is the end angle of the sky part, the starting angle of the sky part is 0°, β i,ground is the starting angle of the ground part, and the ending angle of the ground part is 180°.

9. A high-precision engineering calculation method for back irradiance of a bifacial photovoltaic module according to claim 1, characterized in that The method for calculating the irradiance of the ground reflected part in the back irradiation amplitude in step (5) is as follows: First, calculate the irradiance received by the ground. According to the obtained ground shadow and sky viewing factor, the irradiance GRI received by the ground is n For GRI n =α·(DNI+I cir )+CF sky I sky , where α is the cosine of the solar zenith angle if the ground segment is not blocked, DNI is the direct normal irradiance, and the input is the horizontal direct irradiance conversion formula: HDir = DNI·cos(zenith), CF sky is the sky viewing factor, I sky is the isotropic sky diffuse irradiance; From β i,ground Each 1° segment (j, j+1) from 180° to 180° is projected onto the ground, and the view factor of the segment is calculated separately. The ground irradiance (actualGroundGHI) of the segment (j, j+1) is j ) is obtained by using the range of the projection on the ground as the index. It is assumed that all ground areas between rows have the same irradiance distribution. Therefore, regardless of whether the projection is inside or outside the row, the ground irradiance can be obtained by limiting the index value to the index of the current row. If the projection range exceeds the row spacing, the average irradiance will be used for calculation: Where β i,ground is the starting angle of the ground part, actualGroundGHI j is the ground irradiance of segment (j, j+1), proj x1 is the starting position of (j,j+1) projected on the ground, proj x2 is the end position of the projection of (j, j+1) on the ground, and albedo is the albedo of the ground; The irradiance calculation formula of the direct sky portion in the back side irradiation amplitude in step (5) is as follows: B i,dir =T dir ·(1-Shade i,back ), where T dir is the direct irradiance of the inclined surface, Shade i,back is the backface occlusion score.

10. A device, characterized in that: It utilizes the calculation method described in any one of claims 1 to 9 to perform high-precision calculation of the simulation accuracy and efficiency of the back irradiance of a double-sided photovoltaic module.

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