Method and system for optimizing arrangement parameters of reflective material for lighting of vertical assemblies

Abstract

This invention provides a method and system for optimizing the arrangement parameters of reflective materials for supplemental lighting of vertically mounted photovoltaic modules. The bifacial photovoltaic modules are fixedly installed vertically to the ground, and reflective materials are arranged on the ground between the modules. The method includes: calculating the solar radiation energy density received at any position on the surface of the reflective material at any time T; calculating the total reflected energy that the modules can collect at time T; calculating the real-time power generation of the modules at time T, and obtaining the total annual power generation based on the real-time power generation; and finding the combination of arrangement parameters of the reflective materials that maximizes the total annual power generation, and using this combination as the target parameter combination. The arrangement parameter combination includes the arrangement width, arrangement position, and arrangement tilt angle of the reflective materials. This invention provides a quantitative basis for setting the arrangement parameters of reflective materials for supplemental lighting of vertically mounted bifacial photovoltaic modules, and improves the power generation of vertically mounted bifacial photovoltaic systems by optimizing the arrangement of reflective materials.

Description

Technical Field

[0001] This invention relates to the field of solar photovoltaic power generation technology, specifically to a method and system for optimizing the arrangement parameters of reflective materials used for supplementing light to vertical bifacial photovoltaic modules. Background Technology

[0002] Vertical bifacial photovoltaic (PV) module supports are a type of support system where the support structure and modules are fixed vertically to the ground. They offer advantages such as minimal land coverage, improved utilization of ambient light, some grid peak-shaving capabilities, reduced dust pollution, and no snow cover losses. Therefore, they have promising applications in agricultural-photovoltaic hybrid projects and high-latitude snow-covered areas. However, vertical PV supports suffer from low cosine efficiency, which is lowest at midday when solar energy is strongest. This results in low solar radiation energy utilization efficiency and low utilization rate of solar panels. To improve the utilization rate of vertical bifacial PV modules, high-albedo reflective materials can be placed on the ground to supplement the PV modules with additional light. Testing has verified that this ground-based albedo supplemental lighting method can increase the power generation of vertical bifacial PV systems by 20%–30%.

[0003] Currently, the common application of this method is to lay reflective material flat on the ground under a conventional support. However, there is still a lack of research on how to set parameters such as the placement, shape, and range of the reflective material to maximize the utilization of solar energy resources. Summary of the Invention

[0004] One of the objectives of this invention is to provide a method and system for optimizing the arrangement parameters of reflective materials for supplementing light to vertical bifacial photovoltaic modules, thereby optimizing existing reflective material arrangement methods and improving the power generation efficiency of vertical bifacial photovoltaic systems.

[0005] The technical solution provided by this invention is as follows:

[0006] A method for optimizing the arrangement parameters of reflective material for supplementing light to vertical bifacial photovoltaic modules, wherein the bifacial photovoltaic modules are fixedly installed at a predetermined height above the ground and perpendicular to the ground, and reflective material is arranged on the ground between two rows of bifacial photovoltaic modules to supplement light to the front and back of the bifacial photovoltaic modules. The method for optimizing the arrangement parameters of the reflective material includes:

[0007] Calculate the solar radiation energy density received at any location on the surface of the reflective material at any time T;

[0008] Calculate the total reflected energy that the bifacial photovoltaic module can collect at time T based on the solar radiation energy density;

[0009] Calculate the total direct solar energy that the bifacial photovoltaic module can receive at time T;

[0010] The real-time power generation of the bifacial photovoltaic module at time T is calculated based on the total direct energy and the total reflected energy.

[0011] The total annual power generation of the bifacial photovoltaic module is obtained based on the real-time power generation of the bifacial photovoltaic module at various times within the annual cycle.

[0012] Find the combination of arrangement parameters of the reflective material that maximizes the total annual power generation, and use it as the target parameter combination; the combination of arrangement parameters includes the arrangement width, arrangement position and arrangement tilt angle of the reflective material.

[0013] In some embodiments, calculating the solar radiation energy density received at a location on the surface of the reflective material at time T includes:

[0014] Calculate the real-time solar irradiance of surfaces with different tilt angles at time T;

[0015] If the location on the surface of the reflective material is not blocked by the bifacial photovoltaic module, the solar radiation energy density received at the location is equal to the real-time solar irradiance.

[0016] If the location is blocked by a bifacial photovoltaic module, the solar radiation energy density received at the location is equal to the real-time solar irradiance multiplied by the scattering factor.

[0017] In some embodiments, calculating the total reflected energy that the bifacial photovoltaic module can collect at time T based on the solar radiation energy density includes:

[0018] Calculate the reflected energy density of the bifacial photovoltaic module at any position on the surface of the reflective material captured at time T;

[0019] The total reflected energy that the bifacial photovoltaic module can collect at time T is obtained by integrating the reflected energy density over the area of ​​the reflected material.

[0020] In some embodiments, calculating the reflected energy density at any position on the surface of the reflective material captured by the bifacial photovoltaic module at time T includes:

[0021] Calculate the solid angle of the bifacial photovoltaic module on both sides from any position on the surface of the reflective material.

[0022] The reflected energy density captured by the bifacial photovoltaic module at time T is calculated based on the solid angles on both sides using the Lambert diffuse reflection model.

[0023] In some embodiments, the reflected energy density ρ of the bifacial photovoltaic module at any position on the surface of the reflective material captured at time T is calculated according to the following formula:

[0024]

[0025] Where, η albedo η is the reflectivity of the reflective material. bifa Let I(x,y,T) be the bifacial factor of the component, and let Ω be the solar radiation energy density received at time T at the surface position (x,y,z(x,y)) of the reflective material. L (x,y) and Ω R (x, y) are the solid angles of the rows of photovoltaic modules on the left and right sides of the reflective material at time T relative to the positions (x, y, z(x, y)) on the surface of the reflective material.

[0026] In some embodiments, calculating the total direct solar energy that the bifacial photovoltaic module can receive at time T includes:

[0027] Calculate the solar radiation energy density received by the direct-sunlight surface of a bifacial photovoltaic module at time T;

[0028] Based on the solar radiation energy density and the effective area of ​​the bifacial photovoltaic module, the total direct solar energy received by the bifacial photovoltaic module at time T is obtained.

[0029] In some embodiments, the real-time power generation P of the bifacial photovoltaic module at time T is calculated according to the following formula:

[0030] P(T)=η pe *(E_dir(T)+E_ref(T)*η bifa );

[0031] Where, η pe η represents the photoelectric conversion efficiency of the bifacial photovoltaic module. bifa E_dir is the bifacial factor of the bifacial photovoltaic module, E_ref is the total direct energy, and E_ref is the total reflected energy.

[0032] In some embodiments, the arrangement parameter combination further includes the shape of the reflective material.

[0033] The present invention also provides a photovoltaic system, including multiple bifacial photovoltaic modules and multiple reflective materials. The bifacial photovoltaic modules are fixedly installed at a preset height above the ground and perpendicular to the ground. The reflective materials are arranged on the ground between two rows of bifacial photovoltaic modules to supplement the front and back of the bifacial photovoltaic modules. The arrangement parameters of the reflective materials are set according to the target parameter combination obtained by the arrangement parameter optimization method for supplementing the light of vertical bifacial photovoltaic modules described in any of the preceding claims.

[0034] The method and system for optimizing the arrangement parameters of reflective materials for supplementing light to vertical bifacial photovoltaic modules provided by this invention can bring at least the following beneficial effects:

[0035] 1. This invention optimizes the arrangement of ground reflective materials in a vertical bifacial photovoltaic system, enabling the optimal arrangement of ground reflective materials and maximizing annual power generation gains.

[0036] 2. By combining the use of reflective materials, this invention fully utilizes the bifacial power generation capability of vertical bifacial photovoltaic modules, resulting in a smoother all-day power generation curve for the vertical bifacial photovoltaic system. Attached Figure Description

[0037] The preferred embodiments will now be described in a clear and easy-to-understand manner, with reference to the accompanying drawings, to further explain the above-mentioned characteristics, technical features, advantages, and implementation methods of a method and system for optimizing the arrangement parameters of reflective materials for supplementing light to vertical bifacial photovoltaic modules.

[0038] Figure 1 This is a flowchart of an embodiment of a method for optimizing the arrangement parameters of reflective materials for supplementing light to vertical bifacial photovoltaic modules according to the present invention;

[0039] Figure 2 This is a schematic diagram illustrating the ground-based diffuse reflection supplementary lighting principle of a vertical bifacial photovoltaic module;

[0040] Figure 3 This is a schematic diagram showing the solid angle of the reflective material surface relative to a photovoltaic module;

[0041] Figure 4 This is a flowchart of a specific application scenario embodiment of the present invention. Detailed Implementation

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0043] To keep the drawings concise, only the parts relevant to the invention are shown schematically in each figure, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, components with the same structure or function are shown only schematically, or only one is labeled. In this document, "a" can mean not only "only one" but also "more than one".

[0044] like Figure 2 As shown, taking a two-row vertical bifacial photovoltaic module support as an example, the row spacing D, the effective width B of the bifacial photovoltaic module in the direction perpendicular to the ground, the effective length len, the support height h, and the reflective material arranged on the ground between the bifacial photovoltaic module supports.

[0045] Figure 2 The diagram shows an equivalent photovoltaic module, which can be a single module or a string of multiple photovoltaic modules. If it is the latter, then B and len are the width and length of the module string, respectively. For ease of description, it will be consistently described as a photovoltaic module from now on.

[0046] The design objective of this invention is to maximize the annual total power generation of a photovoltaic system given the known geographical latitude and solar energy resources of the project site. The optimization focuses on the combination of arrangement parameters for the ground-based reflective materials, including the arrangement width b, arrangement position X0, and arrangement tilt angle θ. Figure 2 The placement position X0 is defined as the distance between the center of the reflective material placement and the bifacial photovoltaic module support. Other definitions can also be used, as long as the position of the reflective material placement center can be determined. The placement tilt angle is the tilt angle θ between the reflective material and the ground. Some embodiments also optimize the shape of the reflective material.

[0047] The following is based on Figure 2 Taking the photovoltaic system shown as an example, a coordinate system OXYZ is established with the midpoint of the ground connection between adjacent supports as the origin. The center of the reflective material arrangement coincides with the midpoint of the ground connection between adjacent supports. The solution of the present invention is described in detail.

[0048] In one embodiment of the present invention, such as Figure 1 As shown, a method for optimizing the arrangement parameters of reflective materials used for supplemental lighting of vertical bifacial photovoltaic modules includes:

[0049] Step S100 calculates the solar radiation energy density I(x,y,T) received at any time T at any position (x,y,z(x,y)) on the surface of the reflective material.

[0050] Specifically, step S100 includes:

[0051] Step S110 calculates the real-time solar irradiance GHI(θ,T) of different tilt angle surfaces at time T;

[0052] Step S120 determines whether the surface position (x,y,z(x,y)) of the reflective material is blocked by the bifacial photovoltaic module;

[0053] If the position (x,y,z(x,y)) on the surface of the reflective material is not blocked by the bifacial photovoltaic module, then the solar radiation energy density received at that position is equal to the real-time solar irradiance energy GHI(θ,T).

[0054] If the position (x,y,z(x,y)) on the surface of the reflective material is blocked by the bifacial photovoltaic module, then the solar radiation energy density received at that position is equal to the real-time solar irradiance energy GHI(θ,T) multiplied by the scattering factor.

[0055] Different tilt angle surfaces refer to the reflective material surfaces that correspond to different arrangement tilt angles θ.

[0056] Real-time solar irradiance can be calculated as follows: Based on the time parameter T, obtain the solar hour angle ω and solar declination angle δ at the corresponding moment; based on the solar hour angle ω, solar declination angle δ, and the latitude of the project site... Obtain the solar elevation angle at that moment. Based on the solar elevation angle, obtain the direct solar irradiance (DNI). Calculate the amount of direct solar irradiance (DNI) emitted onto surfaces with different tilt angles to obtain the corresponding real-time solar irradiance (GHI(θ,T)).

[0057] Step S200 calculates the reflected energy density ρ(x,y,T) captured by the bifacial photovoltaic module at time T, and calculates the total reflected energy E_ref(T) at time T based on the reflected energy density.

[0058] Specifically, step S200 includes:

[0059] Step S210 calculates the solid angle of the surface position (x,y,z(x,y)) of the reflective material with respect to the two sides of the bifacial photovoltaic module;

[0060] Step S220 calculates the reflected energy density of the bifacial photovoltaic module at time T based on the solid angle and the Lambert diffuse reflection model.

[0061] Construct a unit sphere (r = 1) with the observation point as its center. The projected area (s) of any object onto this sphere is the solid angle of that object with respect to the observation point. The solid angle Ω(x,y) represents the solid envelope angle formed by the overall outline of the bifacial photovoltaic module for any point (x,y) on the surface of the reflective material.

[0062] like Figure 3 As shown, taking the left-side module as an example, the right-side module is similar. The solid angle Ω(x,y) of the bifacial photovoltaic module relative to any surface position P(x,y,z(x,y)) of the reflective material is calculated using the following formula:

[0063]

[0064] By applying the surface integral to the vertical component, we obtain the solid angle Ω(x,y):

[0065]

[0066] Where P is any position on the surface of the reflective material, P′ is any point on the bifacial photovoltaic module, PP′ is the line connecting point P and point P′, β is the angle between PP′ and the normal of the bifacial photovoltaic module, and A is the entire surface region of the photovoltaic module distribution surface.

[0067] Based on the above formula, the solid angle Ω(x,y) of each row of components relative to any position (x,y) on the ground can be obtained. Assuming that only one row of supports on each side of the reflective material receives the reflected energy, the reflected energy density ρ(x,y,T) at the surface position (x,y,z(x,y)) of the reflective material captured by the system at time T can be calculated using the following formula:

[0068]

[0069] Where, η albedo η is the reflectivity of the reflective material. bifa Let Ω be the bifaciality factor of the photovoltaic module (assuming the direct sunlight side of the module faces right), I(x,y,T) be the solar radiation energy density received at time T at the surface position (x,y,z(x,y)) of the reflective material, and Ω be the solar radiation energy density received at time T. L (x,y) and Ω R (x,y) are the solid angles formed by the left and right side components of the reflective material relative to the surface positions (x,y,z(x,y)) of the reflective material.

[0070] By applying an area integral over the reflected energy density ρ(x,y,T) within the area of ​​the reflective material arrangement, the total reflected energy E_ref that the photovoltaic module can collect at time T is obtained, as shown in the following equation:

[0071] A1 represents the area for arranging reflective materials.

[0072] Step S300 calculates the real-time power generation P of the bifacial photovoltaic module at time T, and obtains the annual total power generation E_annual based on the real-time power generation P.

[0073] Specifically, step S300 includes:

[0074] Step S310 calculates the total direct solar energy E_dir received by the bifacial photovoltaic module at time T according to the following formula:

[0075] E_dir(T)=B*len*GHI(π / 2,T);

[0076] Where E_dir is the total energy received by the direct surface of the module, B is the effective width of the photovoltaic module, len is the effective length of the photovoltaic module, and GHI(π / 2,T) represents the solar radiation energy density on the surface of the photovoltaic module at time T.

[0077] When the sun's direct rays are on the left, E_dir(T) also needs to be multiplied by the two-sided factor η. bifa .

[0078] Step S320 calculates the real-time power generation P of the photovoltaic module at time T based on the total direct solar energy and the total reflected solar energy, specifically according to the following formula:

[0079] P(T)=η pe *(E_dir(T)+E_ref(T)*η bifa );

[0080] Where E_dir is the total direct energy, E_ref is the total reflected energy, and η pe η represents the photoelectric conversion efficiency of a photovoltaic module. bifa This refers to the bifacial factor of a photovoltaic module.

[0081] Step S330: Obtain the annual total power generation E_annual of the photovoltaic module based on the real-time power generation of the photovoltaic module at various times within the annual cycle.

[0082] For example, according to the formula: E_annual=Σ(P(T)*ΔT).

[0083] Step S400: Change the arrangement parameters of the reflective material, find the combination of reflective material arrangement parameters that maximizes the total annual power generation E_annual, and use it as the target parameter combination.

[0084] In one embodiment, the shape of the reflective material z = f(x) is also optimized. That is, the arrangement parameter combination of the reflective material also includes the shape of the reflective material. An iterative method is used to optimize the shape to obtain the parameter combination that maximizes the system's total annual power generation.

[0085] In this embodiment, by comprehensively evaluating the impact of the arrangement parameters (position / shape / range, etc.) of the reflective material and the bracket rotation angle on the power generation of the photovoltaic system, the existing flat arrangement of reflective materials has been improved, providing a quantitative basis for the selection of arrangement parameters of reflective materials.

[0086] In one embodiment of the present invention, a photovoltaic system includes multiple bifacial photovoltaic modules and multiple reflective materials. The bifacial photovoltaic modules are fixedly installed at a preset height above the ground and perpendicular to the ground. The reflective materials are arranged on the ground between two rows of bifacial photovoltaic modules to supplement the light on the front and back of the bifacial photovoltaic modules. The arrangement parameters of the reflective materials are set according to the target parameter combination obtained by the aforementioned optimization method for the arrangement parameters of reflective materials for supplementing light on vertical bifacial photovoltaic modules.

[0087] In this embodiment, the power generation of the photovoltaic system is improved by arranging the reflective material using the target parameter combination (position / range / shape, etc.) obtained in the aforementioned embodiments.

[0088] The present invention also provides a specific application scenario embodiment, which applies the aforementioned method for optimizing the arrangement parameters of reflective materials for supplementing light to vertical bifacial photovoltaic modules to a vertical bifacial photovoltaic module system. The system includes multiple vertical bifacial photovoltaic modules and multiple reflective materials, with the reflective materials arranged on the ground between two rows of bifacial photovoltaic modules.

[0089] The principle of ground reflective supplementary lighting is as follows: Figure 2 As shown, the optimization process for the arrangement parameters of the reflective material is as follows: Figure 4 As shown, the details are as follows:

[0090] 1. Set the basic parameters for the project site and bifacial photovoltaic modules.

[0091] Including the latitude of the project site Solar irradiance resource GHI and its relationship with time GHI(T), where T is a time parameter, the support row spacing D, the effective width B of the bifacial photovoltaic module string, the effective length len, the column height h, etc.

[0092] 2. Initialize the arrangement parameter combination of ground reflective materials

[0093] The arrangement parameter combination includes the arrangement width b, the arrangement position X0, and the arrangement tilt angle θ.

[0094] 3. Calculate the solar radiation energy density I(x,y,T) received at any position (x,y,z(x,y)) on the surface of the reflective material at time T.

[0095] 4. Calculate the reflected energy density ρ(x,y,T) and total reflected energy E_ref(T) captured by the bifacial photovoltaic module.

[0096] Based on the Lambert diffuse reflection model, the solar energy density ρ(x,y,T) and total reflected energy E_ref(T) reflected at any location on the ground as captured in real time by the photovoltaic module are calculated.

[0097] 5. Calculate the real-time power generation P(T) and the annual total power generation E_annual of the system.

[0098] Annual total power generation E_annual=Σ(P(T)ΔT)

[0099] 6. Change the combination of arrangement parameters for the reflective materials, including arrangement width, arrangement position, and arrangement tilt angle, to find the parameter combination that maximizes the system's total annual power generation E_annual.

[0100] Furthermore, for any reflective material shape (z = f(x)), an iterative method is also used to optimize the shape in order to obtain the parameter combination that maximizes the system's annual total power generation E_annual.

[0101] According to calculations, after optimization using the method described in this paper, the system's power generation can be increased by up to 10% compared to the conventional method of simply laying reflective material between adjacent vertical supports, and by 40% to 50% compared to traditional tracker systems.

[0102] It should be noted that the above embodiments can be freely combined as needed. The above are merely preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for optimizing arrangement parameters of reflective material for light supplementing of vertical bifacial photovoltaic modules, the bifacial photovoltaic modules being fixedly installed vertically to the ground at a preset height from the ground, the reflective material being arranged on the ground between the front and rear rows of bifacial photovoltaic modules for light supplementing of the front and back surfaces of the bifacial photovoltaic modules, characterized in that, The method for optimizing the arrangement parameters of the reflective material includes: Calculate the solar radiation energy density received at any location on the surface of the reflective material at any time T; Calculate the total reflected energy that the bifacial photovoltaic module can collect at time T based on the solar radiation energy density; Calculate the total direct solar energy that the bifacial photovoltaic module can receive at time T; The real-time power generation of the bifacial photovoltaic module at time T is calculated based on the total direct energy and the total reflected energy. The total annual power generation of the bifacial photovoltaic module is obtained based on the real-time power generation of the bifacial photovoltaic module at various times within the annual cycle. Find the combination of arrangement parameters of the reflective material that maximizes the total annual power generation, and use it as the target parameter combination; the combination of arrangement parameters includes the arrangement width, arrangement position and arrangement tilt angle of the reflective material. The calculation of the solar radiation energy density received at a location on the surface of the reflective material at time T includes: Calculate the real-time solar irradiance of surfaces with different tilt angles at time T; If the location on the surface of the reflective material is not blocked by the bifacial photovoltaic module, the solar radiation energy density received at the location is equal to the real-time solar irradiance. If the location is blocked by a bifacial photovoltaic module, the solar radiation energy density received at the location is equal to the real-time solar irradiance multiplied by the scattering factor. The total reflected energy that the bifacial photovoltaic module can collect at time T, calculated based on the solar radiation energy density, includes: Calculate the solid angle of the bifacial photovoltaic module on both sides from any position on the surface of the reflective material. The reflected energy density captured by the bifacial photovoltaic module at time T is calculated based on the solid angles on both sides using the Lambert diffuse reflection model. The total reflected energy that the bifacial photovoltaic module can collect at time T is obtained by integrating the reflected energy density over the area of ​​the reflected material.

2. The method for optimizing the arrangement parameters of reflective materials for supplementing light to vertical bifacial photovoltaic modules according to claim 1, characterized in that, The reflected energy density of the bifacial photovoltaic module at any position on the surface of the reflective material, captured at time T, is calculated using the following formula. : ； in, The reflectivity of the reflective material is... For the bifacial factor of photovoltaic modules, Position of the reflective material surface The solar radiation energy density received at time T and The positions of a row of photovoltaic modules on each side of the reflective material at time T relative to the surface of the reflective material are respectively: The solid angle.

3. The method for optimizing the arrangement parameters of reflective materials for supplementing light to vertical bifacial photovoltaic modules according to claim 1, characterized in that, The calculation of the total direct solar energy that the bifacial photovoltaic module can receive at time T includes: Calculate the solar radiation energy density received by the direct-sunlight surface of a bifacial photovoltaic module at time T; Based on the solar radiation energy density and the effective area of ​​the bifacial photovoltaic module, the total direct solar energy received by the bifacial photovoltaic module at time T is obtained.

4. The method for optimizing the arrangement parameters of reflective materials for supplementing light to vertical bifacial photovoltaic modules according to claim 1, characterized in that, The real-time power generation P of the bifacial photovoltaic module at time T is calculated using the following formula: ； in, The photoelectric conversion efficiency of the bifacial photovoltaic module is given. E_dir is the bifacial factor of the bifacial photovoltaic module, E_ref is the total direct energy, and E_ref is the total reflected energy.

5. The method for optimizing the arrangement parameters of reflective materials for supplementing light to vertical bifacial photovoltaic modules according to claim 1, characterized in that, The arrangement parameter combination also includes the shape of the reflective material.

6. A photovoltaic system comprising multiple bifacial photovoltaic modules and multiple reflective materials, wherein the bifacial photovoltaic modules are fixedly installed at a predetermined height above the ground and perpendicular to the ground, and the reflective materials are arranged on the ground between two rows of bifacial photovoltaic modules for supplementing light to the front and back of the bifacial photovoltaic modules, characterized in that, The arrangement parameters of the reflective material are set according to the target parameter combination obtained by the method for optimizing the arrangement parameters of the reflective material for supplementing light to vertical bifacial photovoltaic modules as described in any one of claims 1-5.

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