Total radiation modeling method for inclined plane of back-row double-sided photovoltaic module considering shielding of adjacent modules

Abstract

The invention provides a rear-row double-sided photovoltaic module inclined plane total radiation modeling (model construction method) considering adjacent module shielding, which can construct a rear-row double-sided photovoltaic module inclined plane total radiation model under multiple scenes, and analyzes whether a front-row double-sided photovoltaic module causes shadow shielding to the rear-row double-sided photovoltaic module or not. According to the difference of total radiation received by a ground shadow area and a ground non-shadow area between gaps of the two rows of modules, accurate description of total radiation received by the back row of double-sided photovoltaic modules under the shielding condition is realized by combining sun geometry and a corrected vision field factor model, and based on the model, the double-sided photovoltaic modules can be better researched, and the research on the total radiation received by the back row of double-sided photovoltaic modules is facilitated. On the basis, optimization design, output power prediction and the like of a multi-row photovoltaic system formed by the double-sided photovoltaic modules can be better carried out.

Description

Technical Field

[0001] The present invention belongs to the technical field of photovoltaic power generation, and in particular relates to a method for constructing an inclined total radiation model of rear-row double-sided photovoltaic components taking into account the shielding of adjacent components. Background Art

[0002] By the end of December 2023, the country's cumulative installed power generation capacity will be about 2.92 billion kilowatts, a year-on-year increase of 13.9%, and the cumulative photovoltaic grid-connected installed capacity will be about 609 million kilowatts. Among them, the country's newly added photovoltaic grid-connected installed capacity in 2023 will be 216 million kilowatts, a year-on-year increase of 55.2%.

[0003] In the photovoltaic industry, bifacial photovoltaic modules have gradually become the mainstream of the market. The market share of bifacial photovoltaic modules has increased by 23% in the two years from 2019 to 2021. It is estimated that the market share of bifacial photovoltaic modules will reach 60% by 2027.

[0004] In the layout planning of photovoltaic power stations, it is usually necessary to optimize the overall power generation efficiency of photovoltaic power stations. However, in the case of limited space, the spacing selection of photovoltaic arrays becomes an important factor affecting the utilization of light energy by photovoltaic power stations. In order to increase the capacity of the system, some photovoltaic power stations choose dense component layout when designing the layout, which will cause the front row of photovoltaic components to form shadows on the rear row of photovoltaic components. When the photovoltaic components are in the shadow, the system will have a certain power gap, which will cause the operating frequency and voltage of the system to shift, affecting the reliability of power supply. Therefore, constructing a double-sided photovoltaic component inclined total radiation model that takes into account the shading of adjacent components in a multi-row array system is of great significance to improving the predictability and certainty of photovoltaic power generation output and the smooth operation of the system.

[0005] On this basis, Qi Jun et al. considered that the PU output characteristics of the photovoltaic array may be significantly different from the single-peak PU curve of the typical photovoltaic cell in the presence of shadows, and established a mathematical model of the photovoltaic array under shadow conditions based on the input photovoltaic array structure, light intensity, shadow range and other information in their literature. Starting from the output characteristic model of photovoltaic cells, Xia Yonghong et al. derived the output characteristics of photovoltaic modules when they were blocked, and also evaluated the shadow loss under different inclination angles and spacings when the photovoltaic modules were placed horizontally and vertically, but did not study and analyze the modeling of the modules affected by shadows. Xiao Jingliang et al. studied the output characteristics of systems of various sizes under various shadow conditions to optimize the system structure and revealed the characteristics of the optimal shadow distribution. The related studies of Liu and Jordan, Klucher et al. and Perez et al. provide the currently commonly used modeling methods for the total radiation of the inclined surface of photovoltaic modules, but these models only consider the ideal situation and do not cover the shadow effect of the front row modules on the rear row modules when the module spacing is too small. Li Fen et al. divided the weather types according to the direct ratio, and selected different inclined radiation models under different weather types, achieving a more accurate characterization of the total radiation received by the rear-row components under the shading of the front-row components. In this study, only traditional single-sided photovoltaic components were studied. Zhang Zhen et al. calculated the distribution of radiation received on the back of bifacial photovoltaic components based on the view factor model, indicating that under different installation ground conditions, the micro-mismatch loss caused by the uneven radiation received on the back of bifacial photovoltaic components is different. Liao Dongjin et al. analyzed the impact of ground shadows on the total radiation received on the back of bifacial photovoltaic components, and optimized the model for receiving reflected radiation on the back with the view factor, but did not consider the impact of the existence of the front and back rows on the total ground radiation between the two rows of components, resulting in a larger calculation result. Among them, the above-mentioned research by Zhang Zhen et al. and Liao Dongjin et al. only considered the impact of the shadow of the single-row bifacial component itself on the ground on the radiation received on the back of the component, and did not consider the situation where the front-row components blocked the rear-row components. Nóra Varga et al. used the corner loss model to evaluate the shading loss between the front and rear rows of components in a ground-based photovoltaic power station and compared it with the traditional model. The results showed that the traditional model underestimated the shading loss by 50%-80%, which highlights the importance of detailed shading calculations in photovoltaic power station simulations.

[0006] However, at present, there are few studies on the impact of component shading (i.e., the shadow of the front row of components affects the rear row of components) on the total radiation received by bifacial PV modules, and there is a lack of a refined model that takes into account the shading of adjacent components to calculate the total radiation received by the front and back of the rear row of components. Therefore, the total radiation of the oblique surface of bifacial PV modules calculated based on existing research still has a certain deviation from the actual data, and cannot accurately guide the optimization design and power prediction of multi-row photovoltaic array systems composed of bifacial PV modules. Summary of the invention

[0007] The present invention is made to solve the above problems, and its purpose is to provide a model construction method for constructing a model for calculating the total radiation of the inclined surface of the rear-row bifacial photovoltaic modules taking into account the shading between adjacent modules. The model analyzes the difference in total radiation received by the shadow area and the non-shadow area of ​​the ground between the two rows of gaps under two conditions: whether the front-row modules cause shadow shading to the rear-row modules. Combined with the solar geometry and the corrected view factor model, an accurate description of the total radiation received by the rear-row bifacial photovoltaic modules under shading is achieved. Based on the model, the changing laws of the various radiation components and losses of the bifacial photovoltaic modules under different module spacings and the changes in the total radiation gain received by the bifacial photovoltaic modules under different ground reflectivity and spacings are studied.

[0008] Specifically, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for constructing a slope total radiation model of a rear row of double-sided photovoltaic modules taking into account the shielding of adjacent modules. The method has the following technical features, and comprises the following steps: step S1, obtaining solar radiation data and double-sided photovoltaic module data of a target area; step S2, judging whether there is direct radiation according to the solar radiation data, and dividing the weather type into two types according to the judgment result, and setting corresponding slope total radiation calculation methods for the two weather types, wherein the two weather types are weather type 1 representing a rainy day and weather type 2 representing a sunny or cloudy day; step S3, constructing a weather type based on the solar radiation data and introducing a viewshed factor and an isotropic model. Step S4, judging whether the front-row components block the rear-row components according to the solar radiation data and the installation parameters and size data of the bifacial photovoltaic components, and constructing the obstructed / unobstructed obstructed front and back obstructed front and back obstructed front and back obstructed rear-row bifacial photovoltaic components according to the judgment result and relevant view factors under weather type 2; Step S5, constructing the obstructed rear-row bifacial photovoltaic components according to the obstructed / unobstructed front and back obstructed obstructed front and back obstructed front and back obstructed rear-row bifacial photovoltaic components according to the obstructed / unobstructed front and back obstructed front and back obstructed rear-row photovoltaic components according to the weather type 1.

[0010] The method for constructing a slope total radiation model of a rear row of bifacial photovoltaic modules taking into account the shading of adjacent modules provided by the present invention may also have such a technical feature, wherein in step S1, the solar radiation data includes the horizontal plane total radiation of the sun in the target area, the horizontal plane direct radiation I b , Horizontal scattered radiation I d and reflected radiation, the bifacial photovoltaic module data includes the installation parameters and size specification data of the bifacial photovoltaic module, specifically including: the component spacing d between the front row components and the rear row components, the photovoltaic module length l, the latitude of the photovoltaic module installation location PV panel installation inclination angle β.

[0011] The method for constructing a slope total radiation model of a rear-row double-sided photovoltaic assembly taking into account the shielding of adjacent assemblies provided by the present invention may also have such a technical feature, wherein, in step S2, it is determined whether there is direct radiation according to the solar radiation data. When it is determined that there is no direct radiation, the weather type is weather type 1 representing a rainy day, and the slope total radiation is calculated using a slope radiation model that does not take into account direct radiation and the direct radiation component of the surrounding sun; when it is determined that there is a weather type 2 representing a sunny or cloudy day, the slope total radiation is calculated using a slope radiation model that takes into account direct radiation and the direct radiation component of the surrounding sun. For the weather type 1, the expression for calculating the slope total radiation is:

[0012]

[0013] In the formula, I T1 is the total slope radiation received by the rear components under weather type 1, I Td1 is the scattered radiation received by the front of the rear components under weather type 1, I Tr is the reflected radiation received by the front side of the rear components, is the scattered radiation received by the back of the rear components in weather type 1, is the reflected radiation received by the back of the rear assembly; for the weather type 2, the expression for calculating the total radiation of the slope is:

[0014]

[0015] In the formula, I T2 is the total slope radiation received by the rear components under weather type 2, I Tb is the direct radiation received by the rear components on the front side, I Td2 is the scattered radiation received by the front of the rear components in weather type 2, is the direct radiation received by the back of the rear components, It is the scattered radiation received by the back of the rear-row components in weather type 2. Since there is no direct radiation in weather type 1, direct radiation and direct radiation from the sun are not taken into account, and there is no need to determine whether the front-row components cause shadows to the ground and rear-row components. The scene is simple, and the view factor and isotropic model are directly introduced to construct the oblique radiation received by the front and back of the rear-row components in weather type 1.

[0016] The method for constructing the inclined total radiation model of the rear-row bifacial photovoltaic components taking into account the shielding of adjacent components provided by the present invention may also have such a technical feature, wherein step S3 includes the following sub-steps: step S3-1, calculating the view factor of the front of the rear-row components to the sky, the ground, and the back of the front-row components, the view factor of the ground to the sky, and the view factor of the back of the components to the sky, the ground, and the front of the rear-row components; step S3-2, constructing the inclined total radiation received by the front and back of the rear-row photovoltaic components under weather type 1 according to the view factor calculated in step S3-1 and the isotropic model. Wherein, the ground is the ground between the two rows of components, and the front-row components and the rear-row components are both bifacial photovoltaic components.

[0017] The method for constructing a slope total radiation model of a rear-row bifacial photovoltaic assembly taking into account the shielding of adjacent assemblies provided by the present invention may also have such a technical feature, wherein, in step S3-1, the view factor F of the rear-row assembly facing the sky is R-sky , the viewing factor F of the rear components facing the ground R-g , the viewing factor of the rear component facing the back of the front component The ground-to-sky viewing factor F g-sky , the view factor of the back of the rear components facing the sky View factor of the back of the rear row components to the ground View factor of the back of the front row components facing the sky View factor of the back of the front row components to the ground View factor of the back of the front row component to the front of the rear row component The view factors of the back row facing the ground and the sky are the same as those of the front row facing the sky and the ground. To simplify the description, the view factors of the front row and the back are used instead. The specific expression of the view factor is:

[0018]

[0019]

[0020] In step S3-2, the total oblique radiation received by the front of the rear assembly under weather type 1 is:

[0021]

[0022] In the formula, I T1 is the total slope radiation received by the front of the rear assembly under weather type 1, ρ is the ground reflectivity, I d is the horizontal scattered radiation, is the total radiation received by the back of the front row components, The last term in the above formula represents the reflection from the back of the front row of modules. The surface of photovoltaic modules is generally designed with an anti-reflection (AR) coating to reduce the reflectivity of the photovoltaic module surface to less than 5%, so the reflected radiation from the back of the front row of modules to the front of the rear row of modules can be ignored.

[0023] The total slope radiation received by the back of the rear components under weather type 1 is:

[0024]

[0025] In the formula, represents the total radiation received by the rear components in weather type 1, ρ p is the reflectivity of the front side of the module, I T.R is the total oblique radiation received by the front of the rear row of modules. The last term in the above formula represents the reflection from the front of the rear row of modules, and the reflection from the front of the rear row of modules to the back of the rear row is the same as the reflection from the front of the rear row to the back of the front row. Similarly, since the surface of photovoltaic modules is generally designed with an anti-reflection (AR) coating, the reflectivity of the module surface is very small, so this term can be ignored.

[0026] The method for constructing a slope total radiation model of rear-row bifacial photovoltaic components taking into account the shading of adjacent components provided by the present invention may also have such a technical feature, wherein step S4 includes the following sub-steps: step S4-1, calculating the shadow length of the front-row components according to the solar geometry and the installation parameters and size specifications of the bifacial photovoltaic components; step S4-2, judging whether the shadow length is greater than the component spacing, so as to judge whether the front-row components cause shading to the rear-row components; step S4-3, when step S4-2 is judged to be no, the shadow of the front-row components forms a ground shadow area and a ground non-shadow area on the ground, and the view factors of the front and back of the rear-row components to the ground shadow area and the ground non-shadow area, as well as the view factors of the ground shadow area and the ground non-shadow area to the sky are calculated respectively; step S4-4, according to the said in step S3-1 and step S4-3 The view factor, solar geometry and the calculation method of the slope total radiation corresponding to weather type 2 are used to calculate the slope total radiation received by the front and back sides of the rear-row components without any obstruction under weather type 2; step S4-5, when step S4-2 is judged to be yes, the shadow of the front-row components forms a component shadow area and a component non-shadow area on the front side of the rear-row components, and the proportion of the component shadow area is calculated according to the shadow length, the installation parameters and size specifications of the bifacial photovoltaic components; step S4-6, calculate the view factor of the rear-row component shadow area and the rear-row component non-shadow area to the sky and the ground; step S4-7, according to the proportion, the view factor of step S3-1 and step S4-6, the solar geometry and the calculation method of the slope total radiation corresponding to weather type 2, calculate the slope total radiation received by the front and back sides of the rear-row components when obstruction occurs under weather type 2.

[0027] The method for constructing the inclined total radiation model of the rear-row bifacial photovoltaic modules taking into account the shading of adjacent modules provided by the present invention may also have such a technical feature, wherein in step S4-1, the shadow length expression of the front-row modules is:

[0028] ds=lcosβ+(lsinβcosγ s ) / tanα s

[0029] Where ds is the shadow length, d is the module spacing, l is the module length, β is the module placement inclination angle, α s is the solar altitude angle, γ s is the solar azimuth.

[0030] In step S4-3, the rear row components face the view factor F of the ground shadow area. R-g.s , the viewing factor F of the rear row components facing the non-shadow area of ​​the ground R-g.us , the viewing factor F of the ground shadow area to the skyg.s-sky , the viewing factor F of the ground non-shadow area to the sky g.us-sky , the viewing factor of the back of the rear row components facing the ground shadow area The viewing factor of the back side of the rear row components to the non-shadow area of ​​the ground The viewing factor of the back of the front row components to the ground shadow area The viewing factor of the back of the front row component to the non-shadow area of ​​the ground The view factors of the back row facing the ground shadow area and the ground non-shadow area correspond to the view factors of the front row facing the ground shadow area and the ground non-shadow area respectively. To simplify the description, the view factors of the front row and the back row are used instead. The specific expression of the view factor is:

[0031]

[0032]

[0033] In step S4-4, under the weather type 2, the calculation formula for the total oblique radiation received by the front of the rear assembly without being blocked is:

[0034]

[0035] In the formula, I T2.us is the total radiation received by the front of the rear components when there is no shielding in weather type 2, R b It is the ratio of the direct radiation from the front of the rear-row components to the direct radiation from the horizontal plane, and I0 is the solar radiation reaching the horizontal plane at the upper boundary of the atmosphere.

[0036] Under the weather type 2, the calculation formula for the total oblique radiation received by the back of the rear assembly without any shielding is:

[0037]

[0038] In the formula, Indicates that in weather type 2, the front row components do not form a shadow on the rear row components to block the total radiation received by the back of the components. It is the ratio of direct radiation from the back of the module to direct radiation from the horizontal plane.

[0039] In step S4-5, when the judgment in step S4-2 is yes, the calculation formula of the shadow length formed by the front row component on the rear row component is:

[0040]

[0041] Calculate the proportion of the shadow area of ​​the components on the front of the rear row of components based on the shadow length, installation parameters and size specifications of the bifacial PV modules.

[0042] In step S4-6, the view factor F of the shadow area of ​​the rear row components to the sky Rs-sky , the view factor F of the non-shadow area of ​​the rear component to the sky Rus-sky , the view factor F of the shadow area of ​​the rear component to the ground Rs-g , the view factor F of the non-shadow area of ​​the rear component to the ground Rus-g The expression is:

[0043]

[0044] In step S4-7, under the weather type 2, the calculation formula for the total oblique radiation received by the front of the rear assembly under the shading condition is:

[0045]

[0046] In the formula, I T2.s It represents the total slope radiation received by the front of the rear components under the influence of shadow under weather type 2.

[0047] Under the weather type 2, the calculation formula for the total oblique radiation received by the back of the rear components under the shading condition is:

[0048]

[0049] It indicates that in weather type 2, the front row components cast shadows on the rear row components, blocking the total slope radiation received by the back of the components.

[0050] Function and Effect of the Invention

[0051] According to the method for constructing an inclined total radiation model of rear-row double-sided photovoltaic components taking into account the shading of adjacent components of the present invention, it is possible to construct an inclined total radiation model of rear-row double-sided photovoltaic components in multiple scenarios. The model analyzes the difference in total radiation received by the shadow area and the non-shadow area of ​​the ground between the two rows of components under the two conditions of whether the front-row double-sided photovoltaic components cause shadow shading to the rear-row double-sided photovoltaic components or not. Combined with the solar geometry and the corrected view factor model, an accurate description of the total radiation received by the rear-row double-sided photovoltaic components under shading conditions is achieved. Based on the model, the double-sided photovoltaic components can be better studied, and on this basis, the optimization design of a multi-row photovoltaic system composed of double-sided photovoltaic components and the prediction of output power can be better performed. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a flow chart of a method for constructing an inclined total radiation model of rear-row bifacial photovoltaic modules taking into account the shielding of adjacent modules in an embodiment of the present invention;

[0053] Figure 2It is a flowchart of the sub-steps of the method for constructing the inclined total radiation model of the rear-row bifacial photovoltaic modules taking into account the shading of adjacent modules in an embodiment of the present invention;

[0054] Figure 3 Schematic diagram of the view factors of the front and back sides of a bifacial module to the sky, the ground, and the adjacent back side or front side under weather type 1 in an embodiment of the present invention;

[0055] Figure 4 is a schematic diagram of a situation in which the front row components do not block the rear row components (the front row components themselves form a partial shadow on the ground) under weather type 2 in an embodiment of the present invention;

[0056] Figure 5 It is a schematic diagram of the view factors of the front of the rear-row components facing various areas, the back of the front-row components facing different areas of the ground, and different areas of the ground facing the sky when the front-row components do not block the rear-row components under weather type 2 in an embodiment of the present invention;

[0057] Figure 6 1 is a schematic diagram of a situation in which the front row components shield the rear row components (the ground is completely shaded) in weather type 2 in an embodiment of the present invention;

[0058] Figure 7 Schematic diagram of view factors of the shadow area and non-shadow area on the front side of the rear-row components to the sky and the ground, the ground to the sky, and the back side of the front-row components to the ground when the front-row components block the rear-row components under weather type 2 in an embodiment of the present invention;

[0059] Figure 8 is a schematic diagram showing how the radiation amounts received by the rear row components vary with the spacing between components in an embodiment of the present invention;

[0060] Fig. 9 is a schematic diagram showing how the loss ratio of each radiation amount received by the rear row components varies with the component spacing in an embodiment of the present invention;

[0061] Fig.10 It is a schematic diagram of the variation of the gain of the radiation received on the back side of a double-sided photovoltaic module with the spacing between modules when the ground reflectivity is 0.2 and 0.3 respectively in an embodiment of the present invention. DETAILED DESCRIPTION

[0062] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the following is a detailed description of the method for constructing the inclined total radiation model of the rear-row double-sided photovoltaic components taking into account the shading of adjacent components in combination with the embodiments and drawings.

[0063] <Example>

[0064] Figure 1 is a flow chart of a method for constructing an inclined total radiation model of rear-row bifacial photovoltaic modules taking into account the shading of adjacent modules in this embodiment. Figure 2 It is a flowchart of the sub-steps of the method for constructing the inclined total radiation model of the rear row of bifacial photovoltaic modules taking into account the shading of adjacent modules in this embodiment.

[0065] like Figure 1 and Figure 2 As shown, the method comprises the following steps:

[0066] Step S1, obtaining solar radiation data and bifacial photovoltaic module data of the target area;

[0067] Step S2, judging whether there is direct radiation according to the solar radiation data, and classifying the weather type into two types according to the judgment result, and setting corresponding slope total radiation calculation methods for the two weather types respectively;

[0068] Step S3, constructing a slope total radiation model received by the front and back sides of the rear row components under weather type 1 according to the solar radiation data and introducing a view factor;

[0069] Step S4, judging whether the front-row components block the rear-row components according to the solar radiation data and the installation parameters and size data of the bifacial photovoltaic components, and constructing a slope total radiation model for the front and back sides of the rear-row bifacial photovoltaic components that distinguishes between unblocked and blocked under weather type 2 according to the judgment result and relevant view factors;

[0070] Step S5, constructing a slope total radiation model of the rear-row bifacial photovoltaic components that takes into account the shading of adjacent components based on the slope total radiation model received by the front and back sides of the bifacial photovoltaic components under the weather type 1 and the slope total radiation model of the front and back sides of the rear-row components that distinguish between unshaded and shaded under the weather type 2.

[0071] The above steps will be described in detail below.

[0072] Step S1, obtaining solar radiation data and bifacial photovoltaic module data of a target area.

[0073] The solar radiation data include the horizontal total radiation of the sun in the target area, the horizontal direct radiation I b , Horizontal scattered radiation I d In this embodiment, the solar radiation data comes from the Wuhan Meteorological Station, a national first-level radiation observation station.

[0074] The bifacial PV module data includes the installation parameters and size specification data of the bifacial PV modules, including: the module spacing d between the front and rear modules, the length l of the PV module, the latitude of the location where the PV module is installed PV panel installation inclination angle β.

[0075] The multi-row photovoltaic system contains multiple bifacial photovoltaic modules arranged in a sub-array. If two rows of bifacial photovoltaic modules are randomly selected in the photovoltaic array (except the last row), one row is the front row of bifacial photovoltaic modules (hereinafter referred to as the front row modules), and the other row is the back row of bifacial photovoltaic modules (hereinafter referred to as the back row modules) according to their relative positions. In the actual photovoltaic system arranged in the first row, the second row, ... the nth row (the last row), the calculation method of the total back radiation and the view factor for each area of ​​the first row, the second row, ... the (n-1)th row is the same; the calculation method of the total front radiation and the view factor for each area of ​​the second row, the third row, ... the nth row is the same. Since the first row has no front row shading, the calculation of the total front radiation and the view factor for each area is simple (the same as the conventional single-row front), and since the nth row (the last row) has no back row shading, the calculation of the total back radiation and the view factor for each area is simple (the same as the conventional single-row back).

[0076] Step S2, judging whether there is direct radiation according to the solar radiation data, if it is judged that there is no direct radiation, the weather type is weather type 1 indicating a rainy day, and the slope radiation model that does not take into account direct radiation and the direct radiation component of the surrounding sun is used to calculate the slope total radiation; if it is judged that there is some direct radiation, the weather type is weather type 2 indicating a sunny or cloudy day, and the slope radiation model that takes into account direct radiation and the direct radiation component of the surrounding sun is used to calculate the slope total radiation. For the weather type 1, the expression for calculating the slope total radiation is:

[0077]

[0078] In the formula, I T1 is the total slope radiation received by the rear components under weather type 1, I Td1 is the scattered radiation received by the front of the rear components under weather type 1, I Tr is the reflected radiation received by the front side of the rear components, is the scattered radiation received by the back of the rear components in weather type 1, is the reflected radiation received by the back of the rear assembly; for the weather type 2, the expression for calculating the total radiation of the slope is:

[0079]

[0080] In the formula, I T2 is the total slope radiation received by the rear components under weather type 2, I Tb is the direct radiation received by the rear components on the front side, I Td2 is the scattered radiation received by the front of the rear components in weather type 2, is the direct radiation received by the back of the rear components, It is the scattered radiation received by the back of the rear components in weather type 2.

[0081] Since there is no direct radiation under weather type 1, direct radiation and direct radiation from the sun are not taken into account. There is no need to judge whether the front-row components cause shadows to the ground and rear-row components. The scene is simple, and the view factor and isotropic model are directly introduced to construct the oblique radiation received by the front and back of the rear-row components under weather type 1.

[0082] like Figure 2 As shown, step S3 specifically includes the following sub-steps:

[0083] Step S3-1, calculating the viewing factors of the front and back of the rear row components for each area.

[0084] in, Figure 3 It is a schematic diagram of the viewing factors of the front and back sides of a bifacial module to the sky, the ground, and the adjacent back side or front side under weather type 1 in an embodiment of the present invention.

[0085] like Figure 3 As shown, the viewing factor F of the rear assembly facing the sky is R-sky , the viewing factor F of the rear components facing the ground R-g , the viewing factor of the rear component facing the back of the front component The ground-to-sky viewing factor F g-sky , the view factor of the back of the rear components facing the sky View factor of the back of the rear row components to the ground View factor of the back of the front row components facing the sky View factor of the back of the front row components to the ground View factor of the back of the front row component to the front of the rear row component The view factors of the back row facing the ground and the sky are the same as those of the front row facing the sky and the ground. To simplify the description, the view factors of the front row and the back are used instead. The specific expression of the view factor is:

[0086]

[0087]

[0088] Step S3-2, calculate the total slope radiation received by the front of the rear components under weather type 1, the expression is:

[0089]

[0090] In the formula, I T1 is the total slope radiation received by the front of the rear assembly under weather type 1, ρ is the ground reflectivity, I d is the horizontal scattered radiation, is the total radiation received by the back of the front row components, The last item represents the reflection from the back of the front row of modules. The surface of photovoltaic modules is generally designed with an anti-reflection (AR) coating to reduce the reflectivity of the photovoltaic module surface to less than 5%, so the reflected radiation from the back of the front row of modules to the front of the rear row of modules can be ignored.

[0091] The total slope radiation received by the back of the rear components under weather type 1 is:

[0092]

[0093] In the formula, represents the total radiation received by the rear components in weather type 1, ρ p is the reflectivity of the front side of the module, I T.R is the total oblique radiation received by the front of the rear row of modules. The last term represents the reflection from the front of the rear row (third row) modules. Similarly, since the surface of photovoltaic modules is generally designed with an anti-reflection (AR) coating, the reflectivity of the module surface is very small, so this term can be ignored.

[0094] like Figure 2 As shown, step S4 includes the following sub-steps:

[0095] Step S4-1, calculate the shadow length d of the front row of components according to the installation parameters and size specifications of the bifacial photovoltaic components s .

[0096] Step S4-2, determine the shadow length d s Whether it is greater than the component spacing d, so as to determine whether the front row components block the rear row components.

[0097] Figure 4 It is a schematic diagram of a situation in which the front row components do not block the rear row components (the front row components themselves form a partial shadow on the ground) under weather type 2 in an embodiment of the present invention.

[0098] like Figure 4 As shown, Q1 is the projection point formed by the light through the front row components on the ground, the front row components A1B1 are represented by P, and the rear row components A2B2 are represented by R. The expression for calculating the shadow length ds is as follows:

[0099] ds=l cosβ+(l sinβcosγ s ) / tanα s

[0100] Where, ds is the shadow length, l is the component length, β is the component placement angle, α s is the solar altitude angle, γ s In this embodiment, l is 2.3 m, and β is the optimal inclination angle of 20° in Wuhan area.

[0101] In step S4-3, when the judgment in step S4-2 is no, that is, the front row components do not form a shadow to the rear row components, the viewing factors of the front and back of the rear row components to the ground shadow area and the ground non-shadow area, and the viewing factors of the ground shadow area and the ground non-shadow area to the sky are calculated.

[0102] Figure 5 It is a schematic diagram of the viewing factors of the front of the rear row components facing various areas, the back of the front row components facing different areas of the ground, and different areas of the ground facing the sky when the front row components do not block the rear row components under weather type 2 in an embodiment of the present invention.

[0103] like Figure 5 As shown, the viewing factor F of the rear row components facing the ground shadow area is R-g.s , the viewing factor F of the rear row components facing the non-shadow area of ​​the ground R-g.us , the viewing factor F of the ground shadow area to the sky g.s-sky , the viewing factor F of the ground non-shadow area to the sky g.us-sky , the viewing factor of the back of the rear row components facing the ground shadow area The viewing factor of the back side of the rear row components to the non-shadow area of ​​the ground The viewing factor of the back of the front row components to the ground shadow area The viewing factor of the back of the front row component to the non-shadow area of ​​the ground The view factors of the back row facing the ground shadow area and the ground non-shadow area correspond to the view factors of the front row facing the ground shadow area and the ground non-shadow area respectively. To simplify the description, the view factors of the front row and the back row are used instead. The specific expression of the view factor is:

[0104]

[0105] Step S4-4, under the weather type 2, calculate the total oblique radiation received by the front of the rear row components when the front row components are not blocked. The expression is as follows:

[0106]

[0107] In the formula, I T2.us is the total radiation received by the front of the rear components when there is no shielding in weather type 2, R b It is the ratio of the direct radiation from the front of the rear-row components to the direct radiation from the horizontal plane, and I0 is the solar radiation reaching the horizontal plane at the upper boundary of the atmosphere.

[0108] Under the weather type 2, the calculation formula for the total slope radiation received by the back of the rear row components when the front row components are not blocked is:

[0109]

[0110] In the formula, Indicates that in weather type 2, the front row components do not form a shadow on the rear row components to block the total radiation received by the back of the components. It is the ratio of direct radiation from the back of the module to direct radiation from the horizontal plane.

[0111] Step S4-5: When the judgment in step S4-2 is yes, that is, the front row components form a shadow to the rear row components, the proportion of the component shadow area on the front of the rear row components is calculated according to the shadow length, the installation parameters and the size specifications of the bifacial photovoltaic components.

[0112] Figure 6 It is a schematic diagram of the situation where the front row components block the rear row components (the ground is completely shaded) under weather type 2 in an embodiment of the present invention.

[0113] like Figure 6 As shown, since the calculated shadow length is greater than the component spacing, it is determined that the front-row components block the rear-row components, that is, the shadows cast by the front-row components will cover the front of the rear-row components, forming component shadow areas and component non-shadow areas on the front of the rear-row components. Figure 6 In, l s is the length of the shadow formed by the front row components on the rear row components, l us It is the length of the illuminated area (non-shadow area) on the rear row components.

[0114] The calculation formula for the shadow length formed by the front row components on the rear row components is:

[0115]

[0116] Step S4-6, calculating the view factors of the shadow area and the non-shadow area of ​​the rear-row components to the sky and the ground.

[0117] Figure 7 It is a schematic diagram of the viewing factors of the shadow area and non-shadow area on the front of the rear-row components to the sky and the ground, the ground to the sky, and the back of the front-row components to the ground when the front-row components block the rear-row components under weather type 2 in an embodiment of the present invention.

[0118] like Figure 7 As shown, the viewing factor F of the shadow area of ​​the rear component to the sky Rs-sky , the view factor F of the non-shadow area of ​​the rear component to the sky Rus-sky , the view factor F of the shadow area of ​​the rear component to the ground Rs-g , the view factor F of the non-shadow area of ​​the rear component to the ground Rus-g The expression is:

[0119]

[0120] In step S4-7, under the weather type 2, the calculation formula for the total oblique radiation received by the front of the rear assembly under the shading condition is:

[0121]

[0122] In the formula, I T2.s It represents the total slope radiation received by the front of the rear components under the influence of shadow under weather type 2.

[0123] Under the weather type 2, the calculation formula for the total oblique radiation received by the back of the rear components under the shading condition is:

[0124]

[0125] It indicates that in weather type 2, the front row components cast shadows on the rear row components, blocking the total slope radiation received by the back of the components.

[0126] Step S5, constructing a slope total radiation model for the rear row of bifacial photovoltaic modules that takes into account the shading of adjacent modules based on the slope total radiation model received by the front and back sides of the bifacial photovoltaic modules under weather type 1 and the slope total radiation model distinguishing between unshaded and shaded front and back sides of the bifacial photovoltaic modules under weather type 2.

[0127] That is, by integrating the total radiation models received by the front and back sides of the bifacial photovoltaic modules under different weather types and scenarios constructed in steps S2, S3, and S4, a total radiation model of the inclined surface of the rear-row bifacial photovoltaic modules taking into account the shading of adjacent modules is constructed.

[0128] Figure 8 is a schematic diagram showing how the radiation amounts received by the rear row components vary with the component spacing in this embodiment. Fig. 9 It is a schematic diagram showing how the loss ratio of each radiation amount received by the rear row components varies with the component spacing in this embodiment.

[0129] like Figure 8 and Fig. 9 As shown, in this embodiment, the influence of the change in the spacing between components on the total radiation received by the rear-row components and the loss ratio is also analyzed based on the model. Figure 8 As can be seen from the figure, as the distance between components increases, the radiation received by the rear components increases, among which the increase in direct radiation and total radiation is relatively more obvious. Fig. 9 It can be seen that as the distance between components increases, the loss ratios of various radiation amounts received by the rear-row components decrease, among which the direct radiation loss ratio decreases most significantly.

[0130] Table 1 below shows the change in the loss of direct radiation, scattered radiation, reflected radiation and total radiation received by the rear-row photovoltaic modules as the front-row modules block the rear-row modules, as the modules are spaced apart.

[0131] Table 1 Summary of the proportion of PV module receiving radiation loss as the distance between modules changes

[0132]

[0133] As can be seen from Table 1, as the distance between modules increases, the influence of the shading of the front-row photovoltaic modules on the rear-row photovoltaic modules gradually decreases. Direct radiation and scattered radiation are the main parts of the total radiation received by the modules, and the shading has the most significant effect on the direct radiation and scattered radiation received by the rear-row modules. In this embodiment, when the distance between the front and rear-row modules is 2 meters, the shading loss is nearly 40%, which cannot be ignored.

[0134] In addition, based on the constructed total radiation receiving model of the rear-row bifacial photovoltaic modules taking into account the shading of adjacent modules, the gain brought by the total radiation received on the back side under different ground reflectivities is analyzed as the distance between the front and rear rows of modules changes.

[0135] Fig.10 It is a schematic diagram of the change of the radiation gain received on the back of a bifacial photovoltaic module with the spacing between modules when the reflectivity ρ is 0.2 and 0.3 respectively.

[0136] like Fig.10 As shown, when bifacial photovoltaic modules are installed in a scene with high ground reflectivity, the gain they bring is considerable.

[0137] Functions and Effects of the Embodiments

[0138] According to the method for constructing a slope total radiation model of rear-row bifacial photovoltaic components taking into account the shading of adjacent components provided in this embodiment, the slope total radiation model of rear-row bifacial photovoltaic components taking into account the shading of adjacent components can be constructed. The model analyzes the difference in total radiation received by the shadow area and the non-shadow area of ​​the ground between the two rows of components in the two cases where the front-row bifacial photovoltaic components cause shadow shading to the rear-row bifacial photovoltaic components or not. Combined with the solar geometry and the corrected view factor model, an accurate description of the total radiation received by the rear-row bifacial photovoltaic components under the condition of shading is achieved. Based on the model, the bifacial photovoltaic components can be better studied, and on this basis, the photovoltaic array composed of bifacial photovoltaic components can be better optimized and its output power can be predicted.

[0139] In the embodiment, based on the model, the variation patterns of the radiation components and losses of the bifacial photovoltaic modules at different module spacings, as well as the variation of the total radiation gain received by the back of the bifacial photovoltaic modules at different ground reflectivities and spacings are studied, which verifies the scientific rationality of the method. On this basis, a more accurate prediction of the power generation output of the photovoltaic array set up in the target area can be made, and key parameters such as the module spacing of the photovoltaic array can be optimized.

[0140] The above embodiments are only used to illustrate the specific implementation of the present invention, and the present invention is not limited to the description scope of the above embodiments. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for constructing a slope total radiation model for rear-row bifacial photovoltaic modules taking into account the shading of adjacent modules, characterized in that: The following steps are involved: Step S1, obtaining solar radiation data and bifacial photovoltaic module data of the target area; Step S2, judging whether there is direct radiation according to the solar radiation data, and classifying the weather type into two types according to the judgment result, and setting corresponding slope total radiation calculation methods for the two weather types, wherein the two weather types are respectively weather type 1 representing a rainy day and weather type 2 representing a sunny or cloudy day; Step S3, constructing a slope total radiation model received by the front and back sides of the rear row components under the weather type 1 based on the solar radiation data and introducing a view factor and an isotropic model; Step S4, judging whether the front-row components block the rear-row components according to the solar radiation data and the bifacial photovoltaic component data, and constructing a slope total radiation model for the front and back sides of the rear-row components that distinguish between unblocked / blocked under the weather type 2 according to the judgment result and the view factor corresponding to the judgment result, wherein both the front-row components and the rear-row components are bifacial photovoltaic components; Step S5, constructing a slope total radiation model of the rear-row bifacial photovoltaic components that takes into account the shading of adjacent components based on the slope total radiation model received by the front and back of the rear-row components under the weather type 1 and the slope total radiation model of the front and back of the rear-row components that are distinguished as unshaded / shaded under the weather type 2.

2. The method for constructing a slope total radiation model of rear-row bifacial photovoltaic modules taking into account the shading of adjacent modules according to claim 1, characterized in that: in, In step S1, the solar radiation data includes the horizontal total radiation of the sun in the target area, the horizontal direct radiation I b , Horizontal scattered radiation I d and reflected radiation, The bifacial photovoltaic module data includes the installation parameters and size specification data of the bifacial photovoltaic module, specifically including: the module spacing d between the front row modules and the rear row modules, the length l of the photovoltaic module, the latitude of the location where the photovoltaic module is installed, PV panel installation inclination angle β.

3. The method for constructing a slope total radiation model of rear-row bifacial photovoltaic modules taking into account the shading of adjacent modules according to claim 2, characterized in that: in, In step S2, it is determined whether there is direct radiation according to the solar radiation data. When it is judged as no, the weather type is the weather type 1, and the total slope radiation is calculated using a slope radiation model that does not take into account direct radiation and direct radiation components around the sun. When it is determined that the weather type is the weather type 2, the total slope radiation is calculated using a slope radiation model that takes into account direct radiation and direct radiation components of the sun. For the weather type 1, the expression for calculating the slope total radiation is: In the formula, I T1 is the total slope radiation received by the rear components under weather type 1, I Td1 is the scattered radiation received by the front of the rear components under weather type 1, I Tr is the reflected radiation received by the front side of the rear components, is the scattered radiation received by the back of the rear components in weather type 1, is the reflected radiation received by the back of the rear components, For the weather type 2, the expression for calculating the slope total radiation is: In the formula, I T2 is the total slope radiation received by the rear components under weather type 2, I Tb is the direct radiation received by the rear components on the front side, I Td2 is the scattered radiation received by the front of the rear components in weather type 2, is the direct radiation received by the back of the rear components, It is the scattered radiation received by the back of the rear components in weather type 2.

4. The method for constructing a slope total radiation model of rear-row bifacial photovoltaic modules taking into account the shading of adjacent modules according to claim 2, characterized in that: in, Step S3 includes the following sub-steps: Step S3-1, for the weather type 1, respectively calculating the viewing factors of the front of the rear-row components facing the sky, the ground, and the back of the front-row components, the viewing factors of the ground facing the sky, and the viewing factors of the back of the front-row components facing the sky, the ground, and the front of the rear-row components; Step S3-2, constructing the total oblique radiation received by the front and back of the rear components under the weather type 1 according to the multiple view factors calculated in step S3-1 and the isotropic model, The ground is the ground in the gap between two adjacent rows of components. In step S3-1, the view factor F of the rear row components facing the sky R-sky , the viewing factor F of the rear row components facing the ground R-g , the viewing factor of the front of the rear component facing the back of the front component The ground-to-sky viewing factor F g-sky , the viewing factor of the back of the rear assembly facing the sky The viewing factor of the back side of the rear row components facing the ground The view factor of the back of the front row components facing the sky The viewing factor of the back of the front row component facing the ground The viewing factor of the back side of the front row component to the front side of the rear row component The expressions are: In step S3-2, the total oblique radiation received by the front side of the rear row components under the weather type 1 is: In the formula, I T1 is the total slope radiation received by the front of the rear assembly under weather type 1, ρ is the ground reflectivity, I d is the horizontal scattered radiation, is the total radiation received by the back of the front row components, is the reflectivity of the back side of the module, The total oblique radiation received by the back of the rear row components under the weather type 1 is: In the formula, represents the total radiation received by the rear panel under weather type 1, ρ p is the reflectivity of the front side of the module, I T.R It is the total oblique radiation received by the front side of the rear components.

5. The method for constructing a slope total radiation model of rear-row bifacial photovoltaic modules taking into account the shading of adjacent modules according to claim 4, Features: Wherein, step S4 includes the following sub-steps: Step S4-1, for the weather type 2, calculating the shadow length of the front row components according to the solar geometry and the installation parameters and size specification data of the bifacial photovoltaic components; Step S4-2, determining whether the shadow length is greater than the component spacing, thereby determining whether the front row components block the rear row components; Step S4-3, when the judgment in step S4-2 is no, the shadow of the front-row components forms a ground shadow area and a ground non-shadow area on the ground, and the viewing factors of the front and back of the rear-row components to the ground shadow area and the ground non-shadow area, and the viewing factors of the ground shadow area and the ground non-shadow area to the sky are calculated respectively; Step S4-4, calculating the total slope radiation received by the front and back sides of the rear-row components without any shielding under the weather type 2 according to the multiple view factors calculated in step S3-1 and step S4-3, the solar geometry, and the slope total radiation calculation method corresponding to the weather type 2; Step S4-5, when the judgment in step S4-2 is yes, the ground is entirely in shadow, the shadow of the front row of components forms a component shadow area and a component non-shadow area on the front of the rear row of components, and the proportion of the component shadow area is calculated according to the shadow length, the installation parameters and size specification data of the bifacial photovoltaic components; Step S4-6, respectively calculating the view factors of the shadow area of ​​the rear row components and the non-shadow area of ​​the rear row components to the sky and the ground; Step S4-7, calculating the total slope radiation received by the front and back of the rear components under the condition of shading caused by the weather type 2 according to the proportion, the multiple view factors calculated according to the steps S3-1 and S4-3, the solar geometry, and the slope total radiation calculation method corresponding to the weather type 2, Wherein, in step S4-1, the expression of the shadow length of the front row component is: ds=lcosβ+(lsinβcosγ s ) / thana s Where ds is the shadow length, d is the module spacing, l is the module length, β is the module placement inclination angle, α s is the solar altitude angle, γ s is the solar azimuth, In step S4-3, the rear row components face the view factor F of the ground shadow area. R-g.s , the viewing factor F of the rear row components facing the non-shadow area of ​​the ground R-g.us , the viewing factor F of the ground shadow area to the sky g.s-sky , the viewing factor F of the ground non-shadow area to the sky g.us-sky , the viewing factor of the back of the rear row components facing the ground shadow area The viewing factor of the back side of the rear row components to the non-shadow area of ​​the ground The viewing factor of the back of the front row component to the ground shadow area The viewing factor of the back of the front row component to the non-shadow area of ​​the ground The expressions are: In step S4-4, under the weather type 2, the calculation formula for the total oblique radiation received by the front of the rear assembly without being blocked is: In the formula, I T2.us is the total radiation received by the front of the rear components when there is no shielding in weather type 2, R b is the ratio of the direct radiation from the front of the rear-row components to the direct radiation from the horizontal plane, I0 is the solar radiation reaching the horizontal plane at the upper boundary of the atmosphere, Under the weather type 2, the calculation formula for the total oblique radiation received by the back of the rear assembly without any shielding is: In the formula, Indicates that in weather type 2, the front row components do not form a shadow on the rear row components to block the total radiation received by the back of the components. is the ratio of the direct radiation from the back of the module to the direct radiation from the horizontal plane, In step S4-5, the calculation formula for the shadow length formed by the front row components on the rear row components is: In step S4-6, the view factor F of the shadow area of ​​the rear row components to the sky Rs-sky , the view factor F of the non-shadow area of ​​the rear component to the sky Rus-sky , the view factor F of the shadow area of ​​the rear component to the ground Rs-g , the view factor F of the non-shadow area of ​​the rear component to the ground Rus-g The expressions are: In step S4-7, under the weather type 2, the calculation formula for the total oblique radiation received by the front of the rear assembly under the shading condition is: In the formula, I T2.s It represents the total slope radiation received by the front of the rear components under the influence of shadow under weather type 2. Under the weather type 2, the calculation formula for the total oblique radiation received by the back of the rear assembly under the shading condition is: In the formula, It indicates the total slope radiation received by the back of the front row components when the front row components cast shadows on the rear row components in weather type 2.

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