How to repower a solar power system

Abstract

To provide a repowering method for a solar power generation system, which can maximize the rate of increase in power generation when repowering is performed by replacing an existing single-sided solar panel in the solar power generation system with a double-sided solar panel. [Solution] A repowering method for repowering a solar power generation system 1 by replacing existing single-sided light-receiving solar panels 5 with double-sided light-receiving solar panels 17, in which the solar panels 5 are arranged in an array of four rows in the vertical direction, which is the direction in which the gradient angle θ is set, and multiple rows in the horizontal direction perpendicular to the vertical direction, and when arranging the solar panels 17 in the same array as the solar panels 5, the solar panels 17 are arranged so as to form a daylighting section 19 in which no solar panels 17 are arranged in the second row from the bottom in the vertical direction.

Description

[Technical field]

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

[0002] Conventionally, photovoltaic power generation systems equipped with many solar panels that receive sunlight and generate electricity are known as devices that use sunlight as an energy source. However, if a photovoltaic power generation system continues to generate electricity every day for five or ten years, the power generation efficiency will decrease due to deterioration of the equipment over time, and the amount of electricity generated will decrease. Therefore, repowering may be performed to replace the equipment of the photovoltaic power generation system and restore the amount of electricity generated.

[0003] One example of repowering is replacing existing monofacial solar panels installed in a solar power generation system with bifacial solar panels. A bifacial solar panel can generate electricity not only from the front side of the panel, but also from the back side. Therefore, by utilizing the light reflected from the ground, it is possible to obtain more electricity per unit area than a monofacial panel.

[0004] 2. Description of the Related Art A solar power generation system using a bifacial solar panel is known, for example, from the system described in Patent Document 1. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-110278 A Summary of the Invention [Problem to be solved by the invention]

[0006] If a solar power generation system has been certified under the Feed-in Tariff (FIT) for renewable energy, repowering that would change the output capacity of the entire certified system cannot be performed until the end of the FIT period. For this reason, if existing monofacial solar panels are replaced with bifacial solar panels with a larger output capacity, the number of solar panels must be reduced.

[0007] When repowering by reducing the number of solar panels in this way, the increase in power generation of bifacial solar panels compared to monofacial panels is strongly affected by the arrangement of the replaced bifacial solar panels. For this reason, there has been a demand for an arrangement that can maximize the increase in power generation during repowering.

[0008] An object of the present invention is to provide a method for repowering a solar power generation system, which can maximize the rate of increase in power generation when repowering the solar power generation system by replacing an existing monofacial solar panel with a bifacial solar panel. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the present invention provides a repowering method for a solar power generation system, in which an existing single-sided first solar panel is replaced with a double-sided second solar panel, wherein the first solar panels are arranged in an array of multiple rows in a vertical direction in which a gradient is provided, and at least one row in a horizontal direction perpendicular to the vertical direction, and when the second solar panels are arranged in the same array as the first solar panels, a light collecting section in which the second solar panels are not arranged is formed in intermediate rows in the vertical direction except for the top and bottom rows, and the second solar panels are arranged so that the number of rows of the second solar panels arranged above the light collecting section in the vertical direction is greater than the number of rows of the second solar panels arranged below.

[0010] In a solar power generation system, when repowering by replacing an existing monofacial first solar panel with a bifacial second solar panel, the rate of increase in power generation of the second solar panel relative to the first solar panel is strongly affected by the arrangement of the second solar panel. Specifically, the higher the array height, which is the installation height of the bottom end of the array of the second solar panel, and the wider the array pitch, 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, which is the horizontal length corresponding to the vertical direction of the array, the smaller the rate of increase in power generation.

[0011] Due to the above properties, providing a daylighting section in an intermediate stage in the vertical direction increases the array height of the array above the daylighting section and reduces the array width, resulting in a higher rate of increase in power generation, compared to providing the daylighting section in the topmost or bottommost stage. Also, when providing a daylighting section in an intermediate stage, the array pitch of the upper array can be increased and the effect of the decrease in the rate of increase in power generation due to the increased array width can be reduced, resulting in a higher rate of increase in power generation, when the number of stages above the daylighting section is greater than the number of stages below, compared to when the number of stages above the daylighting section is fewer than the number of stages below.

[0012] As a result of the above, by forming a daylighting section in which no second solar panels are placed in the middle vertical section, and by arranging the second solar panels so that the number of rows of second solar panels placed above the daylighting section in the vertical direction is greater than the number of rows of second solar panels placed below, it is possible to maximize the increase in power generation of bifacial solar panels compared to single-facial solar panels. Effect of the Invention

[0013] According to the present invention, when repowering a photovoltaic power generation system by replacing an existing monofacial solar panel with a bifacial solar panel, the power generation increase rate can be maximized. [Brief description of the drawings]

[0014] [Figure 1]3 is a cross-sectional view corresponding to cross section II in FIG. 2, showing an example of a configuration of a solar power generation system before repowering. [Diagram 2] FIG. 2 is a top view showing an example of an arrangement of a solar panel array before repowering of a solar power generation system. [Diagram 3] FIG. 2 illustrates an example of the pitch between adjacent solar panel arrays before repowering of a solar power generation system. [Figure 4] 2 is a cross-sectional view corresponding to FIG. 1, showing an example of the configuration of a solar power generation system in a first arrangement pattern. FIG. [Diagram 5] FIG. 11 is a diagram showing an example of the pitch between adjacent solar panel arrays in a first arrangement pattern. [Figure 6] FIG. 13 is a diagram illustrating an example of a simulation result of a power generation increase rate in the case of a first arrangement pattern. [Figure 7] 1. FIG. 4 is a cross-sectional view corresponding to FIG. 1, illustrating an example of the configuration of a solar power generation system in a second arrangement pattern. [Figure 8] FIG. 13 is a diagram showing an example of the pitch between adjacent solar panel arrays in the second arrangement pattern. [Figure 9] FIG. 13 is a diagram illustrating an example of a simulation result of a power generation increase rate in the case of a second arrangement pattern. [Figure 10] FIG. 13 is a diagram illustrating an example of a simulation result of a power generation increase rate in the case of a second arrangement pattern. [Figure 11] 1. FIG. 4 is a cross-sectional view corresponding to FIG. 1, illustrating an example of the configuration of a solar power generation system in a third arrangement pattern. [Figure 12] FIG. 13 is a diagram showing an example of the pitch between adjacent solar panel arrays in the third arrangement pattern. [Figure 13] FIG. 13 is a diagram illustrating an example of a simulation result of a power generation increase rate in the case of a third arrangement pattern. [Figure 14] FIG. 13 is a diagram illustrating an example of a simulation result of a power generation increase rate in the case of a third arrangement pattern. [Figure 15]1. FIG. 4 is a cross-sectional view corresponding to FIG. 1, illustrating an example of the configuration of a solar power generation system in a fourth arrangement pattern. [Figure 16] FIG. 13 is a diagram showing an example of the pitch between adjacent solar panel arrays in the fourth arrangement pattern. [Figure 17] FIG. 13 is a diagram illustrating an example of a simulation result of a power generation increase rate in the case of a fourth arrangement pattern. [Figure 18] 1. FIG. 4 is a cross-sectional view corresponding to FIG. 1, illustrating an example of the configuration of a solar power generation system in a fifth arrangement pattern. [Figure 19] FIG. 13 is a diagram showing an example of the pitch between adjacent solar panel arrays in the fifth arrangement pattern. [Figure 20] FIG. 13 is a diagram illustrating an example of a simulation result of a power generation increase rate in the case of a fifth arrangement pattern. [Figure 21] FIG. 13 is a diagram showing a list of simulation results of power generation increase rates for first to fifth arrangement patterns. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0016] In this embodiment, repowering is performed to restore the amount of power generated by the solar power generation system by replacing existing monofacial solar panels installed in the solar power generation system with bifacial solar panels.

[0017] <1. Configuration of the solar power generation system before repowering> The configuration of a solar power generation system according to an embodiment before repowering will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a cross-sectional view corresponding to cross section II in Fig. 2 showing an example of the configuration of a solar power generation system before repowering, Fig. 2 is a top view showing an example of the arrangement of solar panel arrays before repowering of the solar power generation system, and Fig. 3 is a diagram showing an example of the pitch between adjacent solar panel arrays before repowering of the solar power generation system.

[0018] As shown in FIG. 1, the solar power generation system 1 before repowering includes a frame 3 and a plurality of solar panels 5 mounted on the frame 3. The frame 3 includes a plurality of foundations 7 installed on the ground G, a plurality of column frames 9 extending vertically from the foundations 7, a plurality of vertical beam frames 11v extending vertically at the upper ends of the column frames 9, a plurality of horizontal beam frames 11h extending horizontally, and a plurality of diagonal brace frames 13 provided between the column frames 9 and the vertical beam frames 11v at an incline with respect to both frames. The "vertical direction" refers to the direction along a side that is provided with a gradient angle θ with respect to the horizontal direction among the four sides of the periphery of the solar panel 5 mounted on the frame 3, and the "horizontal direction" refers to the direction along a side that is perpendicular to the vertical direction and horizontal to the ground G.

[0019] As shown in FIG. 2, the vertical beam frames 11v and the horizontal beam frames 11h are connected in a lattice pattern, and the solar panels 5 are mounted on the multiple substantially rectangular internal spaces surrounded by the frames. In other words, the mounting base 3 is configured so that the lower surface 5b of the mounted solar panels 5 is exposed to the ground G without being covered. In the example shown in FIG. 2, the solar panels 5 are arranged in a lattice pattern with multiple stages (e.g., four stages) in the vertical direction, which is the direction in which the gradient is provided, and multiple rows (e.g., five rows) in the horizontal direction perpendicular to the vertical direction. In this embodiment, the multiple solar panels 5 arranged in a lattice pattern are referred to as a solar panel array 15. In the example shown in FIG. 2, the solar panel array 15 is composed of 20 solar panels 5.

[0020] The above number of rows (four rows) and number of columns (five columns) are merely examples, and other numbers may be used. For example, the number of rows may be five or more, and the number of columns may be one or a number other than five.

[0021] The solar panel 5 (an example of a first solar panel) is a single-sided solar panel. As shown in Fig. 1, the solar panel 5 has a plurality of solar cells (not shown) on an upper surface 5f (front surface) that receive sunlight and generate electricity, and has no solar cells on a lower surface 5b (rear surface). Note that a solar panel is also called a photovoltaic power generation panel, a solar cell panel, a solar cell module, a photovoltaic power generation module, etc.

[0022] As shown in FIG. 1 and FIG. 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 of FIG. 1 and FIG. 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 the "array height H", and the horizontal length of the vertical length ALv of the solar panel array 15 is the "array width W". As shown in FIG. 3, the solar power generation system 1 has a plurality of racks 3 and solar panel arrays 15 in the vertical direction. The horizontal distance between the lower ends of the solar panel arrays 15 adjacent in the vertical direction is the "array pitch P". 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 solar power generation system 1 is installed.

[0023] If the solar power generation system 1 is certified for the Feed-in Tariff (FIT) for renewable energy, repowering that changes the output capacity of the entire certified system cannot be performed until the end of the FIT period. For this reason, when replacing the existing monofacial solar panels with bifacial solar panels with a large output capacity, it is necessary to reduce the number of solar panels. For example, when the output capacity of the monofacial solar panel 5 is about 250W and the output capacity of the bifacial solar panel 17 to be replaced is about 330W, if the output capacity of the solar panel 17 is about 4 / 3 times that of the solar panel 5, the output capacity of the entire system can be made approximately the same by replacing N solar panels 5 with 3 / 4×N solar panels 17 and performing repowering. For example, in the example shown in FIG. 1 and FIG. 2, the output capacity of the entire 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 bifacial solar panel 17 relative to the monofacial solar panel 5 is strongly affected by the arrangement of the replaced bifacial solar panel 17. Specifically, the higher the array height H of the solar panel 17 array and the wider the array pitch P with the adjacent array, the greater the rate of increase in power generation. On the other hand, the larger the array width W of the solar panel 17 array, the smaller the rate of increase in power generation.

[0025] The power generation increase rate, which has such a property, can be calculated by formula (1). Formula (1) is based on the non-patent document "Yuki Tsuno, Shuto Tsuchida, Noboru Yamada, Takashi Ozeki, "Analysis of the factors of power generation fluctuation due to backside light reception in bifacial solar cells and development of a simple calculation model for the power generation increase rate," Proceedings of the Japan Solar Energy Society (2022), p.219-222.

number

[0026] <2. Simulation results of power generation increase rate after repowering> The inventors of the present application set up multiple arrangement patterns for repowering the solar power generation system 1 having the above-mentioned configuration, in which the output capacity of the solar panels 17 is about 4 / 3 times that of the solar panels 5, by replacing N (e.g., 20) solar panels 5 with 3 / 4×N (e.g., 15) solar panels 17, and performed a simulation of the power generation increase rate for each arrangement pattern using formula (1). The simulation results for each arrangement pattern will be described below.

[0027] (2-1. The first arrangement pattern in which a daylighting section is provided on the bottom level) The configuration of a solar power generation system in the first arrangement pattern will be described with reference to Figures 4 and 5. Figure 4 is a cross-sectional view corresponding to the above-mentioned Figure 1 showing an example of the configuration of a solar power generation system in the first arrangement pattern, and Figure 5 is a diagram showing an example of the pitch between adjacent solar panel arrays in the first arrangement pattern. In Figures 4 and 5, the same reference numerals are used for the same configuration as in the above-mentioned Figures 1 and 3, and the description will be omitted as appropriate.

[0028] As shown in Fig. 4 and Fig. 5, the photovoltaic power generation system 1 after repowering has a mounting base 3 and a plurality of solar panels 17 mounted on the mounting base 3. The mounting base 3 is the same as the mounting base 3 on which the solar panels 5 were arranged. In other words, the existing mounting base 3 is reused. Note that some modifications may be made as necessary, such as changing the metal fittings for fixing the solar panels.

[0029] The solar panel 17 (an example of a second solar panel) is a bifacial solar panel. As shown in FIG. 4, the solar panel 17 has a plurality of solar cells (not shown) on an upper surface 17f (front surface) that receive sunlight and generate electricity, and also has a plurality of solar cells (not shown) on a lower surface 17b (rear surface). Although not shown, a reflecting material is installed on the lower part of the stand 3 and on the surrounding ground G. The solar panel 17 receives reflected light from the reflecting material on the lower surface 17b as well as on the upper surface 17f through the internal space of the stand 3 to generate electricity. The size of the solar panel 17 is approximately the same as that of the single-sided solar panel 5. The sizes of the solar panel 17 and the solar panel 5 may be different within a range in which they can be mounted in the same arrangement on the same stand 3.

[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 so as to form a daylighting section where no solar panels 17 are arranged in the lowest row in the vertical direction. Specifically, as shown in Figs. 4 and 5, in the first arrangement pattern, the solar panels 17 are not arranged in the lowest row in the vertical direction, so that a daylighting section 19 is formed in the lowest row. In the daylighting section 19, sunlight is incident downward through the internal space of the frame 3 and reflected by the reflecting material of the ground G. In the first arrangement pattern, the solar panel array 21 arranged in a grid pattern with three rows in the vertical direction and five rows in the horizontal direction is arranged above the daylighting section 19. In this case, ALv ≒ 3 × PLv. The solar panel array 21 is composed of 15 solar panels 17.

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

[0032] The simulation results of the power generation increase rate for the first arrangement pattern are shown in Fig. 6. As shown in Fig. 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 φBifi (Bifaciality) was set to 0.7. In addition, when the vertical length PLv of the solar panel 5 is 990 mm, the horizontal length PLh is 1662 mm, and the thickness is 46 mm, the array height H of the solar power generation system 1 before repowering is 1.038 m, the array pitch P is 6.486 m, and the vertical length PLv of the bifacial solar panel 17 is 992 mm, the horizontal length PLh is 1640 mm, and the thickness is 30 mm (common to the second to fifth arrangement patterns described later), in the first arrangement pattern, the array height H is 1.379 m, the array width W is 2.838 m, the array pitch P is 6.486 m, the relative height h is 0.49, and the ground occupancy rate gcr is 0.44. As a result of the above, the power generation increase rate is 11.48%.

[0033] (2-2. The second layout pattern in which a daylighting section is provided on the second level from the bottom) The configuration of the solar power generation system in the second arrangement pattern will be described with reference to Fig. 7 and Fig. 8. Fig. 7 is a cross-sectional view corresponding to Fig. 1, which shows an example of the configuration of the solar power generation system in the second arrangement pattern, and Fig. 8 is a diagram showing an example of the pitch between adjacent solar panel arrays in the second arrangement pattern. In Fig. 7 and Fig. 8, the same reference numerals are used for the same configuration as Fig. 1 and Fig. 3, and the description will be omitted as appropriate.

[0034] As shown in Figs. 7 and 8, the solar power generation system 1 after repowering has a frame 3 and a plurality of solar panels 17 mounted on the frame 3. The frame 3 is the same as the frame 3 on which the solar panel 5 was arranged. In other words, the existing frame 3 is reused. The solar panel 17 (an example of a second solar panel) is a bifacial solar panel. As shown in Fig. 7, the solar panel 17 has a plurality of solar cells (not shown) on an upper surface 17f (front surface) that receive sunlight and generate power, and also has a plurality of solar cells (not shown) on a lower surface 17b (rear surface).

[0035] In the second arrangement pattern, when the solar panels 17 are arranged in the same arrangement as the solar panels 5, a daylighting section is formed in which the solar panels 17 are not arranged in the middle sections except for the top and bottom sections in the vertical direction, and the solar panels 17 are arranged so that the number of sections of the solar panels 17 arranged above the daylighting section in the vertical direction is greater than the number of sections of the solar panels 17 arranged below. Specifically, as shown in Figs. 7 and 8, in the second arrangement pattern, the solar panels 17 are not arranged in the second section from the bottom in the vertical direction, so that the daylighting section 19 is formed in the second section from the bottom. In the daylighting section 19, sunlight is incident downward through the internal space of the frame 3 and reflected by the reflecting material of the ground G. In the second arrangement pattern, the solar panels 17 are arranged in one row in the vertical direction and five rows in the horizontal direction in the solar panel array 23 below the daylighting section 19, and are arranged in a lattice pattern in two rows in the vertical direction and five rows in the horizontal direction in the solar panel array 25 above the daylighting section 19. In this case, ALv ≈ 1 × PLv in the solar panel array 23, and ALv ≈ 2 × PLv in the solar panel array 25. The solar panel array 23 is composed of five solar panels 17, and the solar panel array 25 is composed of ten solar panels 17.

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

[0037] 9 and 10 show the simulation results of the power generation increase rate in the case of the second arrangement pattern. FIG. 9 corresponds to the solar panel array 23, and FIG. 10 corresponds to the solar panel array 25. In FIG. 9 and FIG. 10, the gradient angle θ, the coefficients a, b, c, d, e, Albedo (solar reflectance), and φBifi (Bifaciality) are omitted because they are the same values ​​as in FIG. 6. As shown in FIG. 9, in the solar panel array 23 in the second arrangement pattern, the array height H1 is 1.023 m, the array width W1 is 0.930 m, the array pitch P1 is 1.908 m, the relative height h is 1.10, and the ground occupancy rate gcr is 0.49. As a result of the above, the power generation increase rate of the solar panel array 23 is 14.30%. 10, in the solar panel array 25 in the second arrangement pattern, the array height H2 was 1.717 m, the array width W2 was 1.884 m, the array pitch P2 was 4.578 m, the relative height h was 0.91, and the ground occupancy rate gcr was 0.41. As a result of the above, 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 is 14.30×0.33+14.50×0.66≒14.43%.

[0039] (2-3. The third layout pattern in which a daylighting section is provided on the third level from the bottom) The configuration of a solar power generation system in the third arrangement pattern will be described with reference to Fig. 11 and Fig. 12. Fig. 11 is a cross-sectional view corresponding to Fig. 1, which shows an example of the configuration of a solar power generation system in the third arrangement pattern, and Fig. 12 is a diagram showing an example of the pitch between adjacent solar panel arrays in the third arrangement pattern. In Fig. 11 and Fig. 12, the same reference numerals are used for the same configuration as in Fig. 1 and Fig. 3, and the description will be omitted as appropriate.

[0040] As shown in Figs. 11 and 12, the solar power generation system 1 after repowering has a frame 3 and a plurality of solar panels 17 mounted on the frame 3. The frame 3 is the same as the frame 3 on which the solar panel 5 was arranged. In other words, the existing frame 3 is reused. The solar panel 17 (an example of a second solar panel) is a bifacial solar panel. As shown in Fig. 11, the solar panel 17 has a plurality of solar cells (not shown) on an upper surface 17f (front surface) that receive sunlight and generate power, and also has a plurality of solar cells (not shown) on a 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 daylighting section is formed in which the solar panels 17 are not arranged in the middle sections except for the top and bottom sections in the vertical direction, and the solar panels 17 are arranged so that the number of sections of the solar panels 17 arranged above the daylighting section in the vertical direction is less than the number of sections of the solar panels 17 arranged below the daylighting section. Specifically, as shown in Figs. 11 and 12, in the third arrangement pattern, the solar panels 17 are not arranged in the third section from the bottom in the vertical direction, so that the daylighting section 19 is formed in the third section from the bottom. In the daylighting section 19, sunlight is incident downward through the internal space of the frame 3 and reflected by the reflecting material of the ground G. In the third arrangement pattern, the solar panels 17 are arranged in two rows in the vertical direction and five rows in the horizontal direction in the solar panel array 27 below the daylighting section 19, and are arranged in a lattice pattern in one row in the vertical direction and five rows in the horizontal direction in the solar panel array 29 above the daylighting section 19. In this case, ALv ≈ 2 × PLv in the solar panel array 27, and ALv ≈ 1 × PLv in the solar panel array 29. The solar panel array 27 is composed of ten solar panels 17, and the solar panel array 29 is composed of five solar panels 17.

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

[0043] 13 and 14 show the simulation results of the power generation increase rate in the case of the third arrangement pattern. FIG. 13 corresponds to the solar panel array 27, and FIG. 14 corresponds to the solar panel array 29. In FIG. 13 and FIG. 14, the gradient angle θ, the coefficients a, b, c, d, e, Albedo (solar reflectance), and φBifi (Bifaciality) are omitted because they are the same values ​​as in FIG. 6. As shown in FIG. 13, in the solar panel array 27 in the third arrangement pattern, the array height H1 is 1.023 m, the array width W1 is 1.884 m, the array pitch P1 is 2.861 m, the relative height h is 0.54, and the ground occupancy rate gcr is 0.66. As a result of the above, the power generation increase rate of the solar panel array 27 is 7.92%. 14, in the solar panel array 29 in the third arrangement pattern, the array height H2 was 2.064 m, the array width W2 was 0.930 m, the array pitch P2 was 3.625 m, the relative height h was 2.22, and the ground occupancy rate gcr was 0.26. As a result of the above, 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 is 7.92×0.66+22.05×0.33≒12.63%.

[0045] (2-4. The fourth layout pattern in which a daylighting section is provided on the top floor) The configuration of a solar power generation system in the fourth arrangement pattern will be described with reference to Fig. 15 and Fig. 16. Fig. 15 is a cross-sectional view corresponding to Fig. 1, which shows an example of the configuration of a solar power generation system in the fourth arrangement pattern, and Fig. 16 is a diagram showing an example of the pitch between adjacent solar panel arrays in the fourth arrangement pattern. In Fig. 15 and Fig. 16, the same reference numerals are used for the same configuration as Fig. 1 and Fig. 3, and the description will be omitted as appropriate.

[0046] As shown in Figs. 15 and 16, the solar power generation system 1 after repowering has a frame 3 and a plurality of solar panels 17 mounted on the frame 3. The frame 3 is the same as the frame 3 on which the solar panel 5 was arranged. In other words, the existing frame 3 is reused. The solar panel 17 (an example of a second solar panel) is a bifacial solar panel. As shown in Fig. 15, the solar panel 17 has a plurality of solar cells (not shown) on an upper surface 17f (front surface) that receive sunlight and generate power, and also has a plurality of solar cells (not shown) on a 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 so as to form a daylighting section in which no solar panels 17 are arranged in the top row in the vertical direction. Specifically, as shown in Figs. 15 and 16, in the fourth arrangement pattern, the solar panels 17 are not arranged in the top row in the vertical direction, so that a daylighting section 19 is formed in the top row. In the daylighting section 19, sunlight is incident downward through the internal space of the frame 3 and reflected by the reflecting material of the ground G. In the fourth arrangement pattern, the solar panel array 31 arranged in a grid pattern of three rows in the vertical direction and five rows in the horizontal direction is arranged below the daylighting section 19. In this case, ALv ≈ 3 × PLv. The solar panel array 31 is composed of 15 solar panels 17.

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

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

[0050] (2-5. Fifth layout pattern without lighting) The fifth arrangement pattern is an arrangement pattern for comparison with the first to fourth arrangement patterns described above, and is an arrangement pattern in which no daylighting section is provided. 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 solar power generation system in the fifth arrangement pattern will be described with reference to Figs. 18 and 19. Fig. 18 is a cross-sectional view corresponding to Fig. 1 described above, which shows an example of the configuration of the solar power generation system in the fifth arrangement pattern, and Fig. 19 is a diagram showing an example of the pitch between adjacent solar panel arrays in the fifth arrangement pattern. In Figs. 18 and 19, the same reference numerals are used for the configurations similar to those in Figs. 1 and 3 described above, and the description will be omitted as appropriate.

[0051] As shown in Figs. 18 and 19, the solar power generation system 1 after repowering has a frame 3 and a plurality of solar panels 17 mounted on the frame 3. The frame 3 is the same as the frame 3 on which the solar panel 5 was arranged. In other words, the existing frame 3 is reused. The solar panel 17 (an example of a second solar panel) is a bifacial solar panel. As shown in Fig. 15, the solar panel 17 has a plurality of solar cells (not shown) on an upper surface 17f (front surface) that receive sunlight and generate power, and also has a plurality of solar cells (not shown) on a lower surface 17b (rear surface).

[0052] In the fifth arrangement pattern, no daylighting sections are provided when the solar panels 17 are arranged in the same arrangement as the solar panels 5. As shown in Figs. 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, the solar panel array 33 is arranged in a grid pattern with four rows vertically and five columns horizontally. In this case, ALv ≈ 4 × PLv. The solar panel array 33 is composed of 20 solar panels 17.

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

[0054] Figure 20 shows the simulation results of the power generation increase rate in the case of 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 omitted because they are the same values ​​as in Figure 6. As shown in Figure 20, in the fifth arrangement pattern, the array height H is 1.023 m, the array width W is 3.792 m, the array pitch P is 6.486 m, the relative height h is 0.27, and the ground occupancy rate gcr is 0.58. As a result of the above, the power generation increase rate is 7.75%.

[0055] Fig. 21 shows a list of the power generation increase rates of the first to fifth arrangement patterns described above. As shown in Fig. 21, it was found that the power generation increase rate (overall) was highest for the second arrangement pattern in which the second solar panel 17 from the bottom was removed. The third arrangement pattern in which the third solar panel 17 from the bottom was removed was the second highest, the first arrangement pattern in which the bottommost solar panel 17 was removed was the third highest, the fourth arrangement pattern in which the topmost solar panel 17 was removed was the fourth highest, and the fifth arrangement pattern in which the solar panel 17 was not removed was the lowest.

[0056] <3. Effects of the embodiment> As described above, in the case of repowering the photovoltaic power generation system 1 by replacing the existing monofacial solar panels 5 with bifacial solar panels 17, the rate of increase in the amount of power generated by the solar panels 17 relative to the solar panels 5 is strongly affected by the arrangement of the solar panels 17. Specifically, the higher the array height H, which is the installation height of the lower ends of the arrays of the 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 the amount of power generated. 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 the amount of power generated.

[0057] Due to the above properties, providing daylight collecting sections 19 in an intermediate stage in the vertical direction increases the array height H2 of the array above daylight collecting sections 19 and reduces the array width W2, resulting in a higher rate of increase in the amount of power generated, compared to providing daylight collecting sections 19 in the topmost or bottommost stage. Also, when daylight collecting sections 19 are provided in an intermediate stage, the array pitch P2 of the upper array can be increased and the effect of the decrease in the rate of increase in the amount of power generated due to the larger array width W2 can be reduced, resulting in a higher rate of increase in the amount of power generated, compared to a case in which the number of stages above daylight collecting sections 19 is fewer than the number of stages below.

[0058] As described above, by forming daylight collecting section 19 in which solar panels 17 are not arranged in the middle stage in the vertical direction and arranging solar panels 17 so that the number of stages above daylight collecting section 19 in the vertical direction is greater than the number of stages below, it is possible to maximize the rate of increase in the amount of power generated by solar panels 17 relative to solar panels 5. As a result, in solar power generation system 1 after repowering, it is possible to significantly increase the income from selling electricity compared to a case in which repowering is not performed or a case in which repowering is performed in an arrangement pattern other than the second arrangement pattern.

[0059] In particular, in this embodiment, the solar panels 5 are arranged in a vertical four-stage arrangement, and when repowering is performed by replacing the N solar panels 5 with 3 / 4×N solar panels 17, the solar panels 17 are arranged so that a daylight collecting section 19 in which no solar panels 17 are arranged is formed in the second stage from the bottom in the vertical direction. This makes it possible to repower the solar power generation system 1 in which the solar panels 5 are arranged in a vertical four-stage arrangement while maximizing the rate of increase in power generation.

[0060] In particular, in this embodiment, during repowering, the solar panel 17 is arranged on the existing frame 3 on which the solar panel 5 was arranged. This makes it possible to perform repowering by using the existing frame 3 without installing a new frame 3 or modifying it. Therefore, it is possible to reduce the cost required for repowering.

[0061] <4. Modifications> In the above, the output capacity of the solar panels 17 is about 4 / 3 times that of the solar panels 5, and the repowering is performed by replacing N solar panels 5 with 3 / 4×N solar panels 17. However, the output capacity ratio of the solar panels 5, 17 is not limited to the above. For example, when the output capacity of the solar panels 17 is about 5 / 4 times that of the solar panels 5, repowering can be performed by replacing N solar panels 5 with 4 / 5×N solar panels 17, and when the output capacity of the solar panels 17 is about 3 / 2 times that of the solar panels 5, repowering can be performed by replacing N solar panels 5 with 2 / 3×N solar panels 17. That is, the number of solar panels 17 after replacement can be set according to the output capacity ratio of the solar panels 5, 17 so that the output capacity of the entire solar power generation system is approximately the same.

[0062] In this case, if the set number of solar panels 17 is not divisible by the number of columns in the existing arrangement of solar panels 5 (multiple columns x multiple columns), rather than removing all of the solar panels in a specific column to form a daylighting section 19 as in the above embodiment, a column may be created from some of the solar panels removed, and the daylighting section 19 may be formed while adjusting the number.

[0063] In the above, the case where the existing solar panels 5 in the solar power generation system 1 are arranged in four vertical rows has been described as an example, but the solar panels 5 may be arranged in a vertical row other than four rows. For example, when the solar panels 5 are arranged in five vertical rows, the solar panels 17 may be arranged so that the second row from the bottom forms a daylighting section 19 in which the solar panels 17 are not arranged. For example, when the solar panels 5 are arranged in six vertical rows, the solar panels 17 may be arranged so that the second or third row from the bottom forms a daylighting section 19 in which the solar panels 17 are not arranged. Note that, when it is necessary to remove two rows of solar panels due to output capacity constraints, the solar panels 17 may be arranged so that the second and third rows form daylighting sections 19 in which the solar panels 17 are not arranged. When the solar panels 5 are arranged in seven or more vertical rows, the power generation increase rate can be maximized by arranging the solar panels 17 in the same manner as described above.

[0064] In addition to the above, the methods according to the above-described embodiments and the methods according to the modifications may be used in appropriate combination.

[0065] Although not specifically illustrated, the present invention can be implemented with various modifications without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0066] 1. Solar power generation system 3 Mounting 5. Solar panels 15 Solar Panel Array 17. Solar Panels 19 Lighting section 21 Solar Panel Array 23 Solar Panel Array 25 Solar Panel Array 27 Solar Panel Array 29 Solar Panel Array 31 Solar Panel Array 33 Solar Panel Array 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 replacing an existing monofacial first solar panel with a bifacial second solar panel in a solar power generation system, comprising: The first solar panels are arranged on a mounting frame in an arrangement of multiple rows in the vertical direction, which is the direction in which the gradient is provided, and at least one row in a horizontal direction perpendicular to the vertical direction, and when the second solar panels are arranged on the existing mounting frame on which the first solar panels were arranged in the same arrangement as the first solar panels, a daylighting section is formed in which the second solar panels are not arranged in intermediate rows excluding the top and bottom rows in the vertical direction, and the second solar panels are arranged so that the number of rows of the second solar panels arranged above the daylighting section in the vertical direction is greater than the number of rows of the second solar panels arranged below. How to repower a solar power system.

2. Repowering is performed by replacing N of the first solar panels with 3 / 4×N of the second solar panels; The first solar panels are arranged in four rows in the vertical direction, The second solar panel is disposed so as to form the daylight collecting portion in the second row from the bottom in the vertical direction. The method for repowering a photovoltaic power generation system according to claim 1 .

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