Methods for repowering solar power generation systems

Abstract

This invention provides a repowering method for a solar power generation system that maximizes the rate of increase in power generation when repowering a solar power generation system by replacing existing single-sided light-receiving solar panels with double-sided light-receiving solar panels. [Solution] A repowering method for a solar power generation system 1, in which an existing single-sided light-receiving solar panel 5 is replaced with a double-sided light-receiving solar panel 17, wherein the solar panel 5 is arranged in four rows vertically in the direction in which the gradient angle θ is provided and in multiple rows horizontally perpendicular to the vertical direction, and when arranging the solar panel 17 in the same arrangement as the solar panel 5, the solar panel 17 is arranged such that a light-collecting section 19 is formed in the second row from the bottom in the vertical direction where no solar panel 17 is placed.

Description

Technical Field

[0001] The present invention relates to a repowering method for recovering power generation by replacing the solar panels of a solar power generation system.

Background Art

[0002] [[ID=In the past, as a device that uses sunlight as an energy source, a solar power generation system equipped with a large number of solar panels that receive sunlight and generate electricity is known. However, if the solar power generation system continues to generate electricity every day for 5 years or 10 years, the power generation efficiency will decrease due to the aging deterioration of the equipment, and the power generation amount will decrease. Therefore, repowering may be performed by replacing the equipment of the solar power generation system to recover the power generation amount.

[0003] As an example of repowering, there is a method of replacing an existing single-sided light-receiving type solar panel installed in a solar power generation system with a double-sided light-receiving type solar panel. A double-sided light-receiving type solar panel can use sunlight incident on the back surface in addition to the front surface of the panel for power generation. Therefore, by using the reflected light from the ground, it is possible to obtain a larger power generation amount per unit area than the single-sided light-receiving type.

[0004] As a solar power generation system using a double-sided light-receiving type solar panel, for example, the one described in Patent Document 1 is known.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] If a solar power generation system is certified under the Feed-in Tariff (FIT) for renewable energy, it is not possible to repower the entire certified system in a way that changes its output capacity until the FIT period ends. Therefore, when replacing existing single-sided solar panels with double-sided solar panels that have a larger output capacity, it is necessary to reduce the number of solar panels.

[0007] When repowering by reducing the number of solar panels in this way, the rate of increase in power generation between double-sided solar panels and single-sided solar panels is strongly influenced by the arrangement of the replaced double-sided solar panels. Therefore, there was a demand for an arrangement that would maximize the rate of increase in power generation during repowering.

[0008] The object of the present invention is to provide a method for repowering a solar power generation system that can maximize the rate of increase in power generation when repowering a solar power generation system by replacing existing single-sided light-receiving solar panels with double-sided light-receiving solar panels. [Means for solving the problem]

[0009] To achieve the above objective, the present invention provides a repowering method for a photovoltaic power generation system, in which an existing single-sided light-receiving first photovoltaic panel is replaced with a double-sided light-receiving second photovoltaic panel, wherein the first photovoltaic panel is arranged in multiple rows in the vertical direction, which is the direction in which the slope is provided, and in at least one row in the horizontal direction perpendicular to the vertical direction, and when arranging the second photovoltaic panel in the same arrangement as the first photovoltaic panel, a light-collecting section is formed in the intermediate rows, excluding the top and bottom rows in the vertical direction, where the second photovoltaic panel is not placed, and the second photovoltaic panel is arranged such that the number of rows of the second photovoltaic panel located above the light-collecting section in the vertical direction is greater than the number of rows of the second photovoltaic panel located below it.

[0010] In a solar power generation system, when repowering by replacing an existing single-sided light-receiving first solar panel with a double-sided light-receiving second solar panel, the rate of increase in power generation of the second solar panel compared to the first solar panel is strongly influenced by the arrangement of the second solar panel. Specifically, the higher the array height (the installation height of the lower end of the array of the second solar panel) and the wider the array pitch (the horizontal distance between adjacent arrays), the greater the rate of increase in power generation. On the other hand, the larger the array width (the horizontal length corresponding to the vertical length of the array), the smaller the rate of increase in power generation.

[0011] Based on the above properties, placing the light-gathering section in an intermediate section in the vertical direction allows for a higher array height and a smaller array width for the array above the light-gathering section, resulting in a greater increase in power generation. Furthermore, when the light-gathering section is placed in an intermediate section, having more upper sections than lower sections allows for a larger array pitch for the upper array and reduces the impact of the increased array width on the power generation increase rate, resulting in a greater increase in power generation.

[0012] As described above, by forming a light-gathering section in the middle of the vertical direction without placing a second solar panel, and arranging the second solar panels such that the number of rows of second solar panels positioned above the vertical light-gathering section is greater than the number of rows of second solar panels positioned below it, the rate of increase in power generation of a double-sided solar panel compared to a single-sided solar panel can be maximized. [Effects of the Invention]

[0013] According to the present invention, when repowering a solar power generation system by replacing existing single-sided light-receiving solar panels with double-sided light-receiving solar panels, the rate of increase in power generation can be maximized. [Brief explanation of the drawing]

[0014] [Figure 1]It is a cross-sectional view corresponding to the I-I cross-section in FIG. 2 showing an example of the configuration of a solar power generation system before repowering. [Figure 2] It is a top view showing an example of the arrangement of a solar panel array of a solar power generation system before repowering. [Figure 3] It is a diagram showing an example of the pitch between adjacent solar panel arrays of a solar power generation system before repowering. [Figure 4] It is a cross-sectional view corresponding to FIG. 1 showing an example of the configuration of a solar power generation system in the case of the first arrangement pattern. [Figure 5] It is a diagram showing an example of the pitch between adjacent solar panel arrays in the case of the first arrangement pattern. [Figure 6] It is a diagram showing an example of the simulation result of the power generation increase rate in the case of the first arrangement pattern. [Figure 7] It is a cross-sectional view corresponding to FIG. 1 showing an example of the configuration of a solar power generation system in the case of the second arrangement pattern. [Figure 8] It is a diagram showing an example of the pitch between adjacent solar panel arrays in the case of the second arrangement pattern. [Figure 9] It is a diagram showing an example of the simulation result of the power generation increase rate in the case of the second arrangement pattern. [Figure 10] It is a diagram showing an example of the simulation result of the power generation increase rate in the case of the second arrangement pattern. [Figure 11] It is a cross-sectional view corresponding to FIG. 1 showing an example of the configuration of a solar power generation system in the case of the third arrangement pattern. [Figure 12] It is a diagram showing an example of the pitch between adjacent solar panel arrays in the case of the third arrangement pattern. [Figure 13] It is a diagram showing an example of the simulation result of the power generation increase rate in the case of the third arrangement pattern. [Figure 14] It is a diagram showing an example of the simulation result of the power generation increase rate in the case of the third arrangement pattern. [Figure 15]It is a cross-sectional view corresponding to FIG. 1 showing an example of the configuration of a photovoltaic power generation system in the case of the fourth arrangement pattern. [Figure 16] It is a diagram showing an example of the pitch between adjacent photovoltaic panel arrays in the case of the fourth arrangement pattern. [Figure 17] It is a diagram showing an example of the simulation result of the power generation increase rate in the case of the fourth arrangement pattern. [Figure 18] It is a cross-sectional view corresponding to FIG. 1 showing an example of the configuration of a photovoltaic power generation system in the case of the fifth arrangement pattern. [Figure 19] It is a diagram showing an example of the pitch between adjacent photovoltaic panel arrays in the case of the fifth arrangement pattern. <Element ID: [Figure 20] It is a diagram showing an example of the simulation result of the power generation increase rate in the case of the fifth arrangement pattern. [Figure 21] It is a diagram showing a list of the simulation results of the power generation increase rates of the first to fifth arrangement patterns.

Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0016] In this embodiment, re-powering is performed to recover the power generation amount of the photovoltaic power generation system by replacing the existing single-sided light-receiving type photovoltaic panels installed in the photovoltaic power generation system with double-sided light-receiving type photovoltaic panels.

[0017] <1. Configuration of the Photovoltaic Power Generation System Before Repowering> Using FIGS. 1 to 3, the configuration of the photovoltaic power generation system according to the embodiment before repowering will be described. FIG. 1 is a cross-sectional view corresponding to the I-I cross-section in FIG. 2 showing an example of the configuration of the photovoltaic power generation system before repowering, FIG. 2 is a top view showing an example of the arrangement of the photovoltaic panel arrays of the photovoltaic power generation system before repowering, and FIG. 3 is a diagram showing an example of the pitch between adjacent photovoltaic panel arrays of the photovoltaic power generation system before repowering. <0Element ID:

[0018] As shown in Figure 1, the photovoltaic power generation system 1 before repowering has a mounting frame 3 and a plurality of solar panels 5 mounted on the mounting frame 3. The mounting frame 3 has a plurality of foundation sections 7 installed on the ground G, a plurality of column frames 9 extending vertically from the foundation sections 7, a plurality of vertical beam frames 11v extending vertically and a plurality of horizontal beam frames 11h extending horizontally at the upper end of the column frames 9, and a plurality of diagonal bracing frames 13 provided between the column frames 9 and the vertical beam frames 11v at an angle relative to both frames. The "vertical direction" is the direction along the side of the outer circumference of the solar panels 5 mounted on the mounting frame 3 that has a gradient angle θ with respect to the horizontal direction, and the "horizontal direction" is the direction along the side that is perpendicular to the vertical direction and horizontal to the ground G.

[0019] As shown in Figure 2, the vertical beam frame 11v and the horizontal beam frame 11h are connected in a grid pattern, and solar panels 5 are mounted on multiple roughly rectangular internal spaces enclosed by each frame. In other words, the mounting frame 3 is configured so that the lower surface 5b of the mounted solar panels 5 is not covered and is exposed to the ground G. In the example shown in Figure 2, the solar panels 5 are arranged in a grid pattern with multiple rows (e.g., 4 rows) in the vertical direction, which is the direction in which the slope is provided, and multiple columns (e.g., 5 columns) in the horizontal direction perpendicular to the vertical direction. In this embodiment, the multiple solar panels 5 arranged in a grid pattern are called a solar panel array 15. In the example shown in Figure 2, the solar panel array 15 consists of 20 solar panels 5.

[0020] The above numbers of rows (4) and columns (5) are just examples, and other numbers are also acceptable. For example, the number of rows may be 5 or more, and the number of columns may be 1 or more than 5.

[0021] Solar panel 5 (an example of the first solar panel) is a single-sided light-receiving solar panel. As shown in Figure 1, solar panel 5 has multiple solar cells (not shown) on its upper surface 5f (front surface) that receive sunlight and generate electricity, while the lower surface 5b (back surface) does not have any solar cells. Solar panels are also called photovoltaic panels, solar cell panels, solar cell modules, photovoltaic modules, etc.

[0022] As shown in Figures 1 and 2, the vertical length of the solar panel 5 is PLv, the horizontal length is PLh, the vertical length of the solar panel array 15 is ALv, and the horizontal length is ALh. In the example in Figures 1 and 2, ALv ≈ 4 × PLv and ALh ≈ 5 × PLh. The installation height of the lower end of the upper surface 5f of the solar panel array 15 is defined as "array height H," and the horizontal length of the vertical length ALv of the solar panel array 15 is defined as "array width W." As shown in Figure 3, the photovoltaic power generation system 1 has multiple mounting frames 3 and solar panel arrays 15 in the vertical direction. The horizontal distance between the lower ends of adjacent vertical solar panel arrays 15 is defined as "array pitch P." Each of the above dimensions and the gradient angle θ are set to appropriate values ​​according to the region, season, power generation specifications, etc., in which the photovoltaic power generation system 1 is installed.

[0023] If a solar power generation system 1 is certified under the Feed-in Tariff (FIT) for renewable energy, it is not possible to repower the system in a way that changes the overall output capacity until the FIT period ends. Therefore, when replacing existing single-sided solar panels with double-sided solar panels that have a larger output capacity, it is necessary to reduce the number of solar panels. For example, if the output capacity of a single-sided solar panel 5 is approximately 250W and the output capacity of the double-sided solar panel 17 to be replaced is approximately 330W, and the output capacity of solar panel 17 is approximately 4 / 3 times that of solar panel 5, then by repowering the system by replacing N solar panels 5 with 3 / 4 × N solar panels 17, the overall output capacity of the system can be made approximately the same. For example, in the examples shown in Figures 1 and 2, the overall output capacity of the system can be made approximately the same by replacing 20 solar panels 5 with 15 solar panels 17.

[0024] When repowering by reducing the number of solar panels in this way, the rate of increase in power generation of the double-sided solar panels 17 compared to the single-sided solar panels 5 is strongly influenced by the arrangement of the replaced double-sided solar panels 17. Specifically, the higher the array height H of the solar panel array and the wider the array pitch P between adjacent arrays, the greater the rate of increase in power generation. On the other hand, the larger the array width W of the solar panel array, the smaller the rate of increase in power generation.

[0025] The rate of increase in power generation, which has these properties, can be calculated by equation (1). Equation (1) is based on the non-patent literature "Yuki Tsuno, Shuto Tsuchida, Noboru Yamada, and Takashi Ozeki, "Analysis of Factors Affecting Power Generation Fluctuation Due to Back-Surface Reception in Double-Sided Solar Cells and Development of a Simple Model for Calculating the Rate of Increase in Power Generation," Proceedings of the Japan Solar Energy Society (2022), pp. 219-222."

number

[0026] <2. Simulation results of the rate of increase in power generation after repowering> The inventors of the present invention have set up multiple arrangement patterns for repowering a solar power generation system 1 with the above-described configuration, where the output capacity of the solar panels 17 is approximately 4 / 3 times that of the solar panels 5, and where N solar panels 5 (for example, 20 panels) are replaced with 3 / 4 × N solar panels 17 (for example, 15 panels). For each arrangement pattern, they simulated the rate of increase in power generation using equation (1). The simulation results for each arrangement pattern are described below.

[0027] (2-1. First arrangement pattern with a light-gathering section at the bottom) The configuration of the photovoltaic power generation system when the first arrangement pattern is adopted will be explained using Figures 4 and 5. Figure 4 is a cross-sectional view corresponding to Figure 1 above, showing an example of the configuration of the photovoltaic power generation system when the first arrangement pattern is adopted, and Figure 5 is a diagram showing an example of the pitch between adjacent solar panel arrays when the first arrangement pattern is adopted. In Figures 4 and 5, the same reference numerals are used for components as in Figures 1 and 3 above, and explanations are omitted as appropriate.

[0028] As shown in Figures 4 and 5, the repowered photovoltaic power generation system 1 has a mounting frame 3 and multiple solar panels 17 mounted on the mounting frame 3. The mounting frame 3 is the same as the mounting frame 3 on which the solar panels 5 were previously mounted. In other words, the existing mounting frame 3 is reused. Some modifications may be made as needed, such as changing the fittings for fixing the solar panels.

[0029] The solar panel 17 (an example of a second solar panel) is a double-sided solar panel. As shown in Figure 4, the solar panel 17 has multiple solar cells (not shown) on its upper surface 17f (front surface) that receive sunlight and generate electricity, and also has multiple solar cells (not shown) on its lower surface 17b (back surface). Although not shown, reflective material is installed on the ground G below and around the mounting frame 3. In addition to the upper surface 17f, the solar panel 17 also receives reflected light from the reflective material through the internal space of the mounting frame 3 on its lower surface 17b and generates electricity. The size of the solar panel 17 is approximately the same as that of the single-sided solar panel 5. Note that the sizes of the solar panel 17 and the solar panel 5 may differ within the range that they can be mounted on the same mounting frame 3 in the same arrangement.

[0030] In the first arrangement pattern, when the solar panels 17 are arranged in the same arrangement as the solar panels 5, the solar panels 17 are arranged such that a light-collecting section is formed in the bottom row in the vertical direction, where no solar panels 17 are placed. Specifically, as shown in Figures 4 and 5, in the first arrangement pattern, a light-collecting section 19 is formed in the bottom row because no solar panels 17 are placed in the bottom row in the vertical direction. In the light-collecting section 19, sunlight is incident downwards through the internal space of the mounting frame 3 and reflected by the reflective material of the ground G. In the first arrangement pattern, a solar panel array 21, arranged in a grid pattern with 3 rows vertically and 5 columns horizontally, is placed above the light-collecting section 19. In this case, ALv ≈ 3 × PLv. The solar panel array 21 consists of 15 solar panels 17.

[0031] As shown in Figure 4, the installation height of the lower end of the upper surface 17f of the solar panel array 21 is defined as "array height H," and the horizontal length of the vertical length ALv of the solar panel array 21 is defined as "array width W." Also, as shown in Figure 5, the horizontal distance between the lower ends of vertically adjacent solar panel arrays 21 is defined as "array pitch P."

[0032] Figure 6 shows the simulation results of the power generation increase rate when the first arrangement pattern is used. As shown in Figure 6, in this simulation the gradient angle θ was set to 20°, the coefficients a, b, c, d, and e were set to 1.092, 0.864, 9.471, 0.167, and 1.105 respectively, the Albedo (solar reflectance) was set to 90.0%, and the φBifi (Bifaciality) was set to 0.7. Furthermore, assuming that the vertical length PLv of the aforementioned solar panel 5 is 990 mm, the horizontal length PLh is 1662 mm, and the thickness is 46 mm, and that the array height H in the solar power generation system 1 before repowering is 1.038 m, the array pitch P is 6.486 m, and that the vertical length PLv of the double-sided solar panel 17 is 992 mm, the horizontal length PLh is 1640 mm, and the thickness is 30 mm (the second to fifth arrangement patterns described later are also common), in the first arrangement pattern, the array height H was 1.379 m, the array width W was 2.838 m, the array pitch P was 6.486 m, the relative height h was 0.49, and the ground occupancy rate gcr was 0.44. As a result, the power generation increase rate was 11.48%.

[0033] (2-2. Second arrangement pattern in which the light-gathering section is placed on the second row from the bottom) The configuration of the photovoltaic power generation system when the second arrangement pattern is used will be explained using Figures 7 and 8. Figure 7 is a cross-sectional view corresponding to Figure 1 above, showing an example of the configuration of the photovoltaic power generation system when the second arrangement pattern is used, and Figure 8 is a diagram showing an example of the pitch between adjacent solar panel arrays when the second arrangement pattern is used. In Figures 7 and 8, components similar to those in Figures 1 and 3 above are denoted by the same reference numerals, and explanations are omitted as appropriate.

[0034] As shown in Figures 7 and 8, the repowered photovoltaic power generation system 1 has a mounting frame 3 and multiple photovoltaic panels 17 mounted on the mounting frame 3. The mounting frame 3 is the same as the mounting frame 3 on which the photovoltaic panels 5 were placed. In other words, the existing mounting frame 3 is reused. The photovoltaic panels 17 (an example of a second photovoltaic panel) are double-sided photovoltaic panels. As shown in Figure 7, the photovoltaic panel 17 has multiple photovoltaic cells (not shown) on its upper surface 17f (front surface) that receive sunlight and generate electricity, and also has multiple photovoltaic cells (not shown) on its lower surface 17b (back surface).

[0035] In the second arrangement pattern, when the solar panels 17 are arranged in the same arrangement as the solar panels 5, a light-collecting section is formed in the intermediate rows, excluding the top and bottom rows in the vertical direction, and the solar panels 17 are arranged such that the number of rows of solar panels 17 positioned above the light-collecting section in the vertical direction is greater than the number of rows of solar panels 17 positioned below. Specifically, as shown in Figures 7 and 8, in the second arrangement pattern, a light-collecting section 19 is formed in the second row from the bottom by not placing a solar panel 17 in the second row from the bottom in the vertical direction. In the light-collecting section 19, sunlight is incident downwards through the internal space of the mounting frame 3 and reflected by the reflective material of the ground G. In the second arrangement pattern, the solar panels 17 are arranged in a 1-row vertical and 5-column horizontal arrangement in the solar panel array 23 below the light-collecting section 19, and in a grid-like arrangement of 2 rows vertical and 5-column horizontal arrangements in the solar panel array 25 above the light-collecting section 19. In this case, ALv ≈ 1 × PLv for solar panel array 23, and ALv ≈ 2 × PLv for solar panel array 25. Solar panel array 23 consists of 5 solar panels 17, and solar panel array 25 consists of 10 solar panels 17.

[0036] As shown in Figure 7, the installation height of the lower end of the upper surface 17f of the solar panel array 23 is defined as "array height H1", the installation height of the lower end of the upper surface 17f of the solar panel array 25 is defined as "array height H2", the horizontal length of the vertical length ALv of the solar panel array 23 is defined as "array width W1", and the horizontal length of the vertical length ALv of the solar panel array 25 is defined as "array width W2". Furthermore, as shown in Figure 8, the horizontal distance between the lower end of the solar panel array 23 and the lower end of the solar panel array 25 on the same mounting frame 3 is defined as "array pitch P1", and the horizontal distance between the lower end of the solar panel array 25 on one mounting frame 3 and the lower end of the solar panel array 23 on the other mounting frame 3 for vertically adjacent mounting frames 3 is defined as "array pitch P2".

[0037] Figures 9 and 10 show the simulation results of the power generation increase rate for the second arrangement pattern. Figure 9 corresponds to the solar panel array 23, and Figure 10 corresponds to the solar panel array 25. Note that in Figures 9 and 10, the gradient angle θ, coefficients a, b, c, d, e, Albedo (solar reflectance), and φBifi (Bifaciality) are the same values ​​as in Figure 6, so they are not shown. As shown in Figure 9, for the solar panel array 23 in the second arrangement pattern, the array height H1 was 1.023 m, the array width W1 was 0.930 m, the array pitch P1 was 1.908 m, the relative height h was 1.10, and the ground occupancy rate gcr was 0.49. As a result, the power generation increase rate for the solar panel array 23 was 14.30%. As shown in Figure 10, in the second arrangement pattern, the solar panel array 25 had an array height H2 of 1.717m, an array width W2 of 1.884m, an array pitch P2 of 4.578m, a relative height h of 0.91, and a ground occupancy ratio gcr of 0.41. As a result, the power generation increase rate of the solar panel array 25 was 14.50%.

[0038] Since the area ratio of solar panel array 23 to solar panel array 25 is 1:2, the overall power generation increase rate in the second arrangement pattern was 14.30 × 0.33 + 14.50 × 0.66 ≈ 14.43%.

[0039] (2-3. A third arrangement pattern in which the light-gathering section is placed on the third tier from the bottom.) The configuration of the photovoltaic power generation system when the third arrangement pattern is used will be explained with reference to Figures 11 and 12. Figure 11 is a cross-sectional view corresponding to Figure 1 above, showing an example of the configuration of the photovoltaic power generation system when the third arrangement pattern is used, and Figure 12 is a diagram showing an example of the pitch between adjacent solar panel arrays when the third arrangement pattern is used. In Figures 11 and 12, components similar to those in Figures 1 and 3 above are denoted by the same reference numerals, and explanations are omitted as appropriate.

[0040] As shown in Figures 11 and 12, the repowered photovoltaic power generation system 1 has a mounting frame 3 and multiple photovoltaic panels 17 mounted on the mounting frame 3. The mounting frame 3 is the same as the mounting frame 3 on which the photovoltaic panels 5 were placed. In other words, the existing mounting frame 3 is reused. The photovoltaic panels 17 (an example of a second photovoltaic panel) are double-sided photovoltaic panels. As shown in Figure 11, the photovoltaic panel 17 has multiple photovoltaic cells (not shown) on its upper surface 17f (front surface) that receive sunlight and generate electricity, and also has multiple photovoltaic cells (not shown) on its lower surface 17b (back surface).

[0041] In the third arrangement pattern, when the solar panels 17 are arranged in the same arrangement as the solar panels 5, a light-collecting section is formed in the intermediate rows, excluding the top and bottom rows in the vertical direction, and the solar panels 17 are arranged such that the number of rows of solar panels 17 positioned above the light-collecting section in the vertical direction is less than the number of rows of solar panels 17 positioned below. Specifically, as shown in Figures 11 and 12, in the third arrangement pattern, a light-collecting section 19 is formed in the third row from the bottom by not placing a solar panel 17 in the third row from the bottom in the vertical direction. In the light-collecting section 19, sunlight is incident downwards through the internal space of the mounting frame 3 and reflected by the reflective material of the ground G. In the third arrangement pattern, the solar panels 17 are arranged in a grid pattern in a 2-row vertical and 5-column horizontal arrangement in the solar panel array 27 below the light-collecting section 19, and in a grid pattern in a 1-row vertical and 5-column horizontal arrangement in the solar panel array 29 above the light-collecting section 19. In this case, ALv ≈ 2 × PLv for solar panel array 27, and ALv ≈ 1 × PLv for solar panel array 29. Solar panel array 27 consists of 10 solar panels 17, and solar panel array 29 consists of 5 solar panels 17.

[0042] As shown in Figure 11, the installation height of the lower end of the upper surface 17f of the solar panel array 27 is defined as "array height H1", the installation height of the lower end of the upper surface 17f of the solar panel array 29 is defined as "array height H2", the horizontal length of the vertical length ALv of the solar panel array 27 is defined as "array width W1", and the horizontal length of the vertical length ALv of the solar panel array 29 is defined as "array width W2". Also, as shown in Figure 12, the horizontal distance between the lower end of the solar panel array 27 and the lower end of the solar panel array 29 on the same mounting frame 3 is defined as "array pitch P1", and the horizontal distance between the lower end of the solar panel array 29 on one mounting frame 3 and the lower end of the solar panel array 27 on the other mounting frame 3 when two vertically adjacent mounting frames 3 are used is defined as "array pitch P2".

[0043] Figures 13 and 14 show the simulation results of the power generation increase rate for the third arrangement pattern. Figure 13 corresponds to the solar panel array 27, and Figure 14 corresponds to the solar panel array 29. Note that in Figures 13 and 14, the gradient angle θ, coefficients a, b, c, d, e, Albedo (solar reflectance), and φBifi (Bifaciality) are the same values ​​as in Figure 6, so they are not shown. As shown in Figure 13, for the solar panel array 27 in the third arrangement pattern, the array height H1 was 1.023 m, the array width W1 was 1.884 m, the array pitch P1 was 2.861 m, the relative height h was 0.54, and the ground occupancy rate gcr was 0.66. As a result, the power generation increase rate for the solar panel array 27 was 7.92%. Furthermore, as shown in Figure 14, in the third arrangement pattern, the solar panel array 29 had an array height H2 of 2.064 m, an array width W2 of 0.930 m, an array pitch P2 of 3.625 m, a relative height h of 2.22, and a ground occupancy rate gcr of 0.26. As a result, the power generation increase rate of the solar panel array 29 was 22.05%.

[0044] Since the area ratio of solar panel array 27 to solar panel array 29 is 2:1, the overall power generation increase rate in the third arrangement pattern was 7.92 × 0.66 + 22.05 × 0.33 ≈ 12.63%.

[0045] (2-4. Fourth arrangement pattern with a light-gathering section at the top) The configuration of the photovoltaic power generation system when the fourth arrangement pattern is used will be explained using Figures 15 and 16. Figure 15 is a cross-sectional view corresponding to Figure 1 above, showing an example of the configuration of the photovoltaic power generation system when the fourth arrangement pattern is used, and Figure 16 is a diagram showing an example of the pitch between adjacent solar panel arrays when the fourth arrangement pattern is used. In Figures 15 and 16, the same reference numerals are used for components as in Figures 1 and 3 above, and explanations are omitted as appropriate.

[0046] As shown in Figures 15 and 16, the repowered photovoltaic power generation system 1 has a mounting frame 3 and multiple photovoltaic panels 17 mounted on the mounting frame 3. The mounting frame 3 is the same as the mounting frame 3 on which the photovoltaic panels 5 were placed. In other words, the existing mounting frame 3 is reused. The photovoltaic panels 17 (an example of a second photovoltaic panel) are double-sided photovoltaic panels. As shown in Figure 15, the photovoltaic panel 17 has multiple photovoltaic cells (not shown) on its upper surface 17f (front surface) that receive sunlight and generate electricity, and also has multiple photovoltaic cells (not shown) on its lower surface 17b (back surface).

[0047] In the fourth arrangement pattern, when the solar panels 17 are arranged in the same arrangement as the solar panels 5, the solar panels 17 are arranged in such a way that a light-collecting section is formed in the uppermost row in the vertical direction, without any solar panels 17. Specifically, as shown in Figures 15 and 16, in the fourth arrangement pattern, a light-collecting section 19 is formed in the uppermost row because no solar panels 17 are placed in the uppermost row in the vertical direction. In the light-collecting section 19, sunlight is incident downwards through the internal space of the mounting frame 3 and reflected by the reflective material of the ground G. In the fourth arrangement pattern, a solar panel array 31, arranged in a grid pattern with 3 rows vertically and 5 columns horizontally, is located below the light-collecting section 19. In this case, ALv ≈ 3 × PLv. The solar panel array 31 consists of 15 solar panels 17.

[0048] As shown in Figure 15, the installation height of the lower end of the upper surface 17f of the solar panel array 31 is defined as "array height H," and the horizontal length of the vertical length ALv of the solar panel array 31 is defined as "array width W." Also, as shown in Figure 16, the horizontal distance between the lower ends of vertically adjacent solar panel arrays 31 is defined as "array pitch P."

[0049] Figure 17 shows the simulation results of the power generation increase rate for the fourth arrangement pattern. Note that in Figure 17, the gradient angle θ, coefficients a, b, c, d, e, Albedo (solar reflectance), and φBifi (Bifaciality) are the same values ​​as in Figure 6 and are therefore omitted from the illustration. As shown in Figure 17, in the fourth arrangement pattern, the array height H was 1.023m, the array width W was 2.838m, the array pitch P was 6.486m, the relative height h was 0.36, and the ground occupancy rate gcr was 0.44. As a result, the power generation increase rate was 10.77%.

[0050] (2-5. Fifth arrangement pattern without a light-gathering section) The fifth arrangement pattern is an arrangement pattern for comparison with the first to fourth arrangement patterns described above, and is an arrangement pattern without a light-gathering section. For example, when the FIT period ends and it is possible to change the output capacity of the entire system, the fifth arrangement pattern can be used. The configuration of the photovoltaic power generation system when the fifth arrangement pattern is used will be explained using Figures 18 and 19. Figure 18 is a cross-sectional view corresponding to Figure 1 above, showing an example of the configuration of the photovoltaic power generation system when the fifth arrangement pattern is used, and Figure 19 is a diagram showing an example of the pitch between adjacent solar panel arrays when the fifth arrangement pattern is used. In Figures 18 and 19, the same reference numerals are used for components as in Figures 1 and 3 above, and explanations are omitted as appropriate.

[0051] As shown in Figures 18 and 19, the repowered photovoltaic power generation system 1 has a mounting frame 3 and multiple photovoltaic panels 17 mounted on the mounting frame 3. The mounting frame 3 is the same as the mounting frame 3 on which the photovoltaic panels 5 were placed. In other words, the existing mounting frame 3 is reused. The photovoltaic panels 17 (an example of a second photovoltaic panel) are double-sided photovoltaic panels. As shown in Figure 15, the photovoltaic panel 17 has multiple photovoltaic cells (not shown) on its upper surface 17f (front surface) that receive sunlight and generate electricity, and also has multiple photovoltaic cells (not shown) on its lower surface 17b (back surface).

[0052] In the fifth arrangement pattern, the solar panels 17 are arranged in the same arrangement as the solar panels 5, but no light-gathering section is provided. As shown in Figures 18 and 19, in the fifth arrangement pattern, the same number of solar panels 17 as the solar panels 5 are arranged in the same arrangement. That is, in the fifth arrangement pattern, a solar panel array 33 is arranged in a grid pattern with 4 rows vertically and 5 columns horizontally. In this case, ALv ≈ 4 × PLv. The solar panel array 33 consists of 20 solar panels 17.

[0053] As shown in Figure 18, the installation height of the lower end of the upper surface 17f of the solar panel array 33 is defined as "array height H," and the horizontal length of the vertical length ALv of the solar panel array 33 is defined as "array width W." Also, as shown in Figure 19, the horizontal distance between the lower ends of vertically adjacent solar panel arrays 33 is defined as "array pitch P."

[0054] Figure 20 shows the simulation results of the power generation increase rate for the fifth arrangement pattern. Note that in Figure 20, the gradient angle θ, coefficients a, b, c, d, e, Albedo (solar reflectance), and φBifi (Bifaciality) are the same values ​​as in Figure 6 and are therefore omitted from the illustration. As shown in Figure 20, in the fifth arrangement pattern, the array height H was 1.023m, the array width W was 3.792m, the array pitch P was 6.486m, the relative height h was 0.27, and the ground occupancy rate gcr was 0.58. As a result, the power generation increase rate was 7.75%.

[0055] Figure 21 shows a list of the power generation increase rates for the first to fifth arrangement patterns described above. As shown in Figure 21, the second arrangement pattern, in which the second-to-last row of solar panels 17 from the bottom is removed, shows the highest overall power generation increase rate. The third arrangement pattern, in which the third-to-last row of solar panels 17 from the bottom is removed, is the second highest, the first arrangement pattern, in which the bottom-most solar panel 17 is removed, is the third highest, the fourth arrangement pattern, in which the top-most solar panel 17 is removed, is the fourth highest, and the fifth arrangement pattern, in which no solar panels 17 are removed, is the lowest.

[0056] <3. Effects of the Embodiment> As explained above, in a photovoltaic power generation system 1, when repowering is performed by replacing existing single-sided light-receiving solar panels 5 with double-sided light-receiving solar panels 17, the rate of increase in power generation of solar panels 17 compared to solar panels 5 is strongly influenced by the arrangement of solar panels 17. Specifically, the higher the array height H, which is the installation height of the lower end of the array of solar panels 17, and the wider the array pitch P, which is the horizontal distance between adjacent arrays, the greater the rate of increase in power generation. On the other hand, the larger the array width W, which is the horizontal length corresponding to the vertical direction of the array, the smaller the rate of increase in power generation.

[0057] Based on the above properties, placing the light-collecting section 19 in an intermediate section compared to placing it in the uppermost or lowermost section in the vertical direction allows for a higher array height H2 and a smaller array width W2 of the upper array of the light-collecting section 19, resulting in a larger increase in power generation. Furthermore, when the light-collecting section 19 is placed in an intermediate section, having more upper sections than lower sections allows for a larger array pitch P2 of the upper array and reduces the impact of the decrease in power generation increase rate due to the larger array width W2, resulting in a larger increase in power generation.

[0058] As described above, by forming a light-collecting section 19 in which no solar panels 17 are placed in the intermediate vertical sections, and by arranging the solar panels 17 such that the number of upper sections is greater than the number of lower sections above the vertical light-collecting section 19, the rate of increase in power generation of the solar panels 17 relative to the solar panels 5 can be maximized. As a result, in the repowered solar power generation system 1, it is possible to significantly increase the revenue from selling electricity compared to cases where no repowering is performed or when repowering is performed with an arrangement pattern other than the second arrangement pattern.

[0059] Furthermore, in this embodiment, the solar panels 5 are arranged in a four-tiered vertical configuration. When repowering is performed by replacing N solar panels 5 with 3 / 4 × N solar panels 17, the solar panels 17 are arranged such that a light-gathering section 19 is formed in the second tier from the bottom in the vertical direction, where no solar panels 17 are placed. This allows the solar power generation system 1, in which the solar panels 5 are arranged in a four-tiered vertical configuration, to be repowered while maximizing the rate of increase in power generation.

[0060] Furthermore, in this embodiment, the solar panels 17 are placed on the existing mounting frame 3 where the solar panels 5 were previously mounted during repowering. This allows repowering to be performed using the existing mounting frame 3 without installing or modifying a new mounting frame 3. Therefore, the cost required for repowering can be reduced.

[0061] <4. Variation> The above explanation uses the example of a case where the output capacity of solar panel 17 is approximately 4 / 3 times that of solar panel 5, and repowering is performed by replacing N solar panels 5 with 3 / 4 × N solar panels 17. However, the output capacity ratio of solar panels 5 and 17 is not limited to the above. For example, if the output capacity of solar panel 17 is approximately 5 / 4 times that of solar panel 5, then repowering should be performed by replacing N solar panels 5 with 4 / 5 × N solar panels 17. If the output capacity of solar panel 17 is approximately 3 / 2 times that of solar panel 5, then repowering should be performed by replacing N solar panels 5 with 2 / 3 × N solar panels 17. In other words, the number of solar panels 17 after replacement should be set so that the total output capacity of the solar power generation system is approximately the same, according to the output capacity ratio of solar panels 5 and 17.

[0062] In this case, if the number of solar panels 17 set is not divisible by the number of columns in the existing arrangement of solar panels 5 (multiple rows x multiple columns), instead of removing all the solar panels in a particular row to form the light-collecting section 19 as in the above embodiment, a row with some of the solar panels removed may be provided to balance the number and form the light-collecting section 19.

[0063] Furthermore, while the above description has taken the example of a solar power generation system 1 where the existing solar panels 5 are arranged in a four-row vertical configuration, the solar panels 5 may be arranged in a vertical configuration other than four rows. For example, if the solar panels 5 are arranged in five rows vertically, the solar panels 17 may be arranged such that a light-collecting section 19 is formed in the second row from the bottom where no solar panels 17 are placed. Also, for example, if the solar panels 5 are arranged in six rows vertically, the solar panels 17 may be arranged such that a light-collecting section 19 is formed in either the second or third row from the bottom where no solar panels 17 are placed. If it is necessary to remove two rows of solar panels due to output capacity constraints, the solar panels 17 may be arranged such that a light-collecting section 19 is formed in both the second and third rows where no solar panels 17 are placed. Even if the solar panels 5 are arranged in seven or more rows vertically, the rate of increase in power generation can be maximized by arranging the solar panels 17 in the same manner as described above.

[0064] In addition to what has already been described above, the methods according to the above embodiments and the methods according to the modified embodiments may be used in appropriate combinations.

[0065] Furthermore, although not to be exemplified individually, the present invention may be implemented with various modifications without departing from its spirit. [Explanation of Symbols]

[0066] 1. Solar power generation system 3. Stand 5. Solar panels 15 Solar panel arrays 17 Solar panels 19 Light-gathering section 21 Solar panel arrays 23 Solar panel arrays 25 Solar Panel Arrays 27 Solar panel arrays 29 Solar panel arrays 31 Solar panel arrays 33 Solar panel arrays G ground gcr ground occupancy P Array Pitch P1 Array Pitch P2 Array Pitch W Array width W1 Array width W2 Array Width θ gradient angle

Claims

1. A repowering method for a solar power generation system, which involves replacing an existing single-sided light-receiving first solar panel with a double-sided light-receiving second solar panel, The first solar panels are arranged in multiple rows in the vertical direction, which is the direction in which the slope is provided, and in at least one row in the horizontal direction perpendicular to the vertical direction. When arranging the second solar panels in the same arrangement as the first solar panels, light-gathering sections are formed in the intermediate rows, excluding the top and bottom rows in the vertical direction, where the second solar panels are not placed. The second solar panels are arranged such that the number of rows of second solar panels positioned above the light-gathering sections in the vertical direction is greater than the number of rows of second solar panels positioned below them. Methods for repowering solar power generation systems.

2. Repowering is performed by replacing N of the first solar panels with 3 / 4 × N of the second solar panels. The first solar panel is arranged in a four-tiered vertical configuration. The second solar panel is arranged such that the light-collecting section is formed in the second row from the bottom in the vertical direction. A method for repowering a solar power generation system according to claim 1.

3. The second solar panel is placed on the existing mounting frame where the first solar panel was installed. A method for repowering a solar power generation system according to claim 1 or 2.

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