Installation method and solar power generation system

Abstract

The objective is to provide a method for installing a solar power generation system and a solar power generation system that can improve the conversion rate of solar energy to electricity per unit area and can easily compensate for the decrease in electricity due to aging or other factors. [Solution] A method for installing a solar power generation system and a solar power generation system 1, comprising a first solar power generation system 10 comprising a first solar cell string 12 having a plurality of first solar cell modules 11 and a first power converter 13, and a second solar power generation system 20 comprising a second solar cell string 22 having a plurality of second solar cell modules 21 and a second power converter 23, wherein each second solar cell module 21 is installed on the back side of the first solar cell module 11 so as to generate electricity using only indirect sunlight.

Description

Technical Field

[0001] The present invention relates to a method for installing a photovoltaic power generation system and a photovoltaic power generation system.

Background Art

[0002] Conventionally, as a photovoltaic power generation system, there is provided a solar cell string including a plurality of solar cell modules electrically connected in series to each other, and a power conversion device (PCS: power conditioner) electrically connected to the solar cell string, and the generated power is linked to the power grid of a power transmission and distribution company by the power conversion device, or a power consumer constructs the power conversion device as its own facility to use the generated power at home (self-consumption). Such a photovoltaic power generation system is configured such that a plurality of solar cell modules are installed so as not to overlap each other vertically.

[0003] In this type of photovoltaic power generation system, the generated power will decrease due to the aging deterioration of the solar cell modules and the like. Since the solar cell module has a structure in which materials with different coefficients of thermal expansion, such as semiconductors and metals, are electrically joined, the generated power gradually decreases in the long term due to thermal stress caused by repeated cold and heat day and night or seasonally. In addition, members may be suddenly damaged during lightning strikes, storms, etc., and it is inevitable that power generation failure will occur in the entire solar cell module due to such factors.

[0004] On the other hand, in recent years, new solar cells having a perovskite crystal as a power generation layer have been developed (see, for example, Non-Patent Document 1). Since perovskite solar cells can be manufactured, for example, by a coating process or a printing process on a resin substrate, it is expected that they can be manufactured at a lower cost than silicon-based solar cells. In addition, since products that are lighter and have flexibility (flexibility) than silicon-based solar cells can also be manufactured, applications to various uses are expected.

Prior Art Documents

Non-Patent Documents

[0005] [Non-Patent Document 1] Riki Miyasaka, "The Emergence of Perovskite Solar Cells," Gendai Kagaku (Modern Chemistry), Tokyo Kagaku Dojin Co., Ltd., February 18, 2014, March 2014 issue, pp. 24-32. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, in conventionally installed solar power generation systems, the amount of power supplied from multiple solar cell modules to the power converter is limited by the energy conversion efficiency of each solar cell module. Therefore, regardless of the type of solar cell module used, the solar cell module alone cannot improve the conversion rate of solar energy to electricity per unit area (energy utilization rate) of the solar power generation system.

[0007] Furthermore, there was a problem in that it was difficult to compensate for the decrease in power generated by existing solar power generation systems when the power output decreased due to the aging of solar cell modules, etc.

[0008] The present invention has been proposed in view of the aforementioned problems, and its objective is to provide a method for installing a solar power generation system and a solar power generation system that can improve the conversion rate of solar energy to electricity per unit area and can easily compensate for the amount of electricity lost due to aging or other factors. [Means for solving the problem]

[0009] The present invention relates to a method for installing a photovoltaic power generation system, comprising: a first photovoltaic power generation system comprising a first solar cell string having a plurality of first solar cell modules electrically connected in series with each other, and a first power converter electrically connected to the first solar cell string; and a second photovoltaic power generation system comprising a second solar cell string having a plurality of second solar cell modules electrically connected in series with each other, and a second power converter electrically connected to the second solar cell string, wherein each of the second solar cell modules is installed on the back side of the first solar cell modules so as to generate electricity using only indirect sunlight.

[0010] In the installation method of the photovoltaic power generation system of the present invention, it is preferable that the second solar cell module is a perovskite solar cell.

[0011] In the installation method of the photovoltaic power generation system of the present invention, in the above configuration, the third photovoltaic power generation system comprises a third solar cell string having a plurality of transparent third solar cell modules electrically connected in series with each other, and a third power converter electrically connected to the third solar cell string, and it is preferable to install the third solar cell modules on top of the first solar cell modules and each second solar cell module on top of the first solar cell modules so that each of the first solar cell modules generates electricity from sunlight that has passed through the third solar cell modules, and to install each of the second solar cell modules on top of the first solar cell modules so that they face away from the first solar cell modules.

[0012] The present invention relates to a photovoltaic power generation system comprising: a first photovoltaic power generation system comprising a first solar cell string having a plurality of first solar cell modules electrically connected in series with each other, and a first power converter electrically connected to the first solar cell string; and a second photovoltaic power generation system comprising a second solar cell string having a plurality of second solar cell modules electrically connected in series with each other, and a second power converter electrically connected to the second solar cell string, wherein each of the second solar cell modules is installed on the back side of the first solar cell module so as to generate electricity using only indirect sunlight.

[0013] In the photovoltaic power generation system of the present invention, it is preferable that the second solar cell module is a perovskite solar cell.

[0014] The photovoltaic power generation system of the present invention further comprises a third photovoltaic power generation system comprising a third solar cell string having a plurality of transmissive third solar cell modules electrically connected in series with each other, and a third power converter electrically connected to the third solar cell string, wherein the third solar cell modules are installed on top of the first solar cell modules so that each of the first solar cell modules generates electricity from sunlight transmitted through the third solar cell modules, and each of the second solar cell modules is installed on top of the first solar cell modules so that it faces away from the first solar cell modules. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a method for installing a solar power generation system and a solar power generation system that can improve the conversion rate of solar energy to electricity per unit area and can easily compensate for the amount of electricity lost due to aging or other factors. [Brief explanation of the drawing]

[0016] [Figure 1] This is a diagram schematically showing the configuration of a photovoltaic power generation system according to a first embodiment installed by the installation method of a photovoltaic power generation system according to an embodiment of the present invention. [Figure 2] This is a diagram showing the configuration of the first solar cell module shown in FIG. 1. [Figure 3] This is a diagram showing the configuration of the first solar cell string shown in FIG. 1. [Figure 4] This is a diagram showing the configuration of the second solar cell module shown in FIG. 1. [Figure 5] This is a diagram showing the cross-sectional structure of the second solar cell module shown in FIG. 4. [Figure 6] This is a diagram showing one aspect of the arrangement of a plurality of first solar cell modules and a plurality of second solar cell modules in the photovoltaic power generation system shown in FIG. 1. [Figure 7] This is a side view of the photovoltaic power generation system shown in FIG. 6. [Figure 8] This is a diagram showing another aspect of the arrangement of a plurality of first solar cell modules and a plurality of second solar cell modules in the photovoltaic power generation system shown in FIG. 1. [Figure 9] This is a diagram schematically showing the configuration of a photovoltaic power generation system according to a modified example. [Figure 10] This is a diagram showing one aspect of the arrangement of a plurality of first solar cell modules, a plurality of second solar cell modules, and a plurality of third solar cell modules in the photovoltaic power generation system according to the modified example shown in FIG. 9.

Embodiments for Carrying Out the Invention

[0017] The installation method of the photovoltaic power generation system of the present invention is a photovoltaic power generation system having a first photovoltaic string including a plurality of first photovoltaic modules electrically connected in series to each other, and a first power conversion device electrically connected to the first photovoltaic string, and a second photovoltaic string including a plurality of second photovoltaic modules electrically connected in series to each other, and a second power conversion device electrically connected to the second photovoltaic string. In the photovoltaic power generation system, each second photovoltaic module is installed on the back side of the first photovoltaic module so as to generate power only by indirect sunlight.

[0018] Further, the photovoltaic power generation system of the present invention is a photovoltaic power generation system having a first photovoltaic string including a plurality of first photovoltaic modules electrically connected in series to each other, and a first power conversion device electrically connected to the first photovoltaic string, and a second photovoltaic string including a plurality of second photovoltaic modules electrically connected in series to each other, and a second power conversion device electrically connected to the second photovoltaic string. Each second photovoltaic module is installed on the back side of the first photovoltaic module so as to generate power only by indirect sunlight.

[0019] The photovoltaic power generation system of the present invention can be installed by the installation method of the photovoltaic power generation system of the present invention.

[0020] Various types of solar cells can be used as the first solar cell module, as long as they are capable of generating electricity from sunlight. Furthermore, the physical arrangement of the multiple first solar cell modules can be set as appropriate, provided that the first solar cell string comprises a plurality of first solar cell modules electrically connected in series with each other, and each first solar cell module is installed to generate electricity from total solar radiation, including direct and indirect sunlight.

[0021] Multiple first solar cell modules can be electrically connected in series with each other and arranged in a straight line, or they can be electrically connected in series with each other and arranged in multiple layers vertically (folded arrangement).

[0022] Multiple first solar cell modules may be transmissive, allowing sunlight to pass through, or opaque, preventing sunlight from passing through.

[0023] Various types of solar cells can be used as the second solar cell module, as long as they are capable of generating electricity from indirect sunlight. Furthermore, the physical arrangement of each second solar cell module can be set as appropriate, provided that the second solar cell string comprises multiple second solar cell modules electrically connected in series with each other, and each second solar cell module is installed on the back side of the first solar cell module so as to generate electricity only from indirect light that does not include direct sunlight.

[0024] Multiple second solar cell modules can be electrically connected in series and physically arranged in a linear fashion, or they can be electrically connected in series and arranged in multiple vertical rows (folded arrangement). Furthermore, the installation location of the second solar power generation system can be arbitrary, as long as it does not reduce the power generation of the first solar power generation system.

[0025] Multiple second solar cell modules may be transmissive, allowing sunlight to pass through, or opaque, preventing sunlight from passing through, but it is preferable to use perovskite solar cells. Since perovskite solar cells can generate electricity efficiently even in low light conditions, using perovskite solar cells as multiple second solar cell modules allows for effective power generation using only indirect light, without direct sunlight.

[0026] Here, direct sunlight refers to sunlight that directly reaches the solar cell module on a clear day when there is no scattering of sunlight by clouds. Indirect sunlight, on the other hand, does not include direct sunlight, but rather sunlight that is scattered by structures, etc., during its journey to the solar cell module and reaches the module indirectly, and also includes scattered sunlight by clouds, etc. In other words, the first solar power generation system is installed to generate electricity using both direct and indirect sunlight, while the second solar power generation system is installed to generate electricity using only indirect sunlight.

[0027] Furthermore, the back side of the first solar cell module refers to the back side that faces away from the light-receiving surface of the first solar cell module, and is the area that overlaps with the first solar cell module when viewed from a direction perpendicular to the light-receiving surface of the first solar cell module. In other words, when viewed from a direction perpendicular to the light-receiving surface of the first solar cell module, the second solar cell module is installed so as to be hidden on the back side of the first solar cell module.

[0028] The first solar cell module and the second solar cell module may be identical in shape or size, number, and power generation performance, or they may be different from each other.

[0029] Furthermore, the first solar power generation system may be one that was already installed at the time the second solar power generation system is installed, or it may be one that is newly installed at the time the second solar power generation system is installed.

[0030] According to the installation method or solar power generation system of the present invention having such a configuration, multiple first solar cell modules generate electricity by receiving direct and indirect sunlight, and multiple second solar cell modules each generate electricity from indirect sunlight on the back side of the first solar cell modules. Therefore, the second solar power generation system can be operated independently in parallel with the first solar power generation system. Furthermore, since all of the multiple second solar cell modules are located on the back side of the first solar cell modules, the conversion rate of solar energy to electricity per unit area in the entire installation site of the solar power generation system can be increased.

[0031] Furthermore, according to the installation method or solar power generation system of the present invention, if the power generation of an existing solar power generation system decreases due to the aging of solar cell modules, by installing a plurality of second solar cell modules on the back side of the plurality of first solar cell modules whose power generation has decreased due to aging, etc., in the opposite direction to the first solar cell modules, the power that has decreased due to aging, etc. can be easily compensated for by the power generation of the plurality of second solar cell modules.

[0032] Furthermore, according to the installation method or solar power generation system of the present invention, the first solar cell module and the second solar cell module can be replaced individually. Therefore, if the power generation performance of either the first solar cell module or the second solar cell module deteriorates, the one whose power generation performance deterioration is acceptable can be used as is, and only the other module whose power generation performance deterioration is not acceptable needs to be replaced. There is no need to replace the first solar cell module and the second solar cell module at the same time. Accordingly, according to the installation method or solar power generation system of the present invention, the maintenance costs of the solar power generation system can be reduced.

[0033] The present invention will be described in more detail below with reference to the drawings.

[0034] The photovoltaic power generation system 1 shown in Figure 1, according to one embodiment of the present invention, is installed by the installation method for a photovoltaic power generation system according to one embodiment of the present invention. This photovoltaic power generation system 1 includes a first photovoltaic power generation system 10 and a second photovoltaic power generation system 20.

[0035] The first solar power generation system 10 includes a first solar cell string 12 comprising a plurality of first solar cell modules 11 electrically connected in series with each other, and a first power converter (PCS: power conditioner) 13 electrically connected to the first solar cell string 12. The first power converter 13 converts the DC power of the first solar cell string 12 into AC power.

[0036] In the case shown in Figure 1, the first solar cell string 12 is configured such that multiple first solar cell modules 11 are arranged side by side in the horizontal direction of the paper. There may be gaps (for example, a few millimeters) between adjacent first solar cell modules 11.

[0037] The first solar cell string 12 can be configured such that the multiple first solar cell modules 11 are electrically connected in series with each other, and the physical arrangement of the multiple first solar cell modules 11 can be changed as appropriate. Furthermore, in the case shown in Figure 1, the first photovoltaic power generation system 10 is configured to have only one first solar cell string 12, but it is not limited to this configuration, and can also be configured to have a solar cell array with multiple first solar cell strings 12. In this case, the multiple first solar cell strings 12 can be electrically connected to each other using a junction box, and then electrically connected to the first power converter 13 via the junction box.

[0038] The first power converter 13 is a so-called power conditioner (PCS) equipped with an inverter. The first power converter 13 converts the DC power generated by the multiple first solar cell modules 11 into AC power and outputs it to the power grid. In other words, the first solar power generation system 10 is configured such that the power generated by the multiple first solar cell modules 11 is connected to the power grid of the power transmission and distribution company by the first power converter 13.

[0039] The first power converter 13 can be configured to control power using the MPPT (Maximum Power Point Tracking) method to maximize the power generated by all first solar cell strings 12 when the first photovoltaic power generation system 10 is configured to have multiple first solar cell strings 12.

[0040] Alternatively, the first power converter 13 may be constructed as part of the owner's own equipment and configured to utilize (consume) the electricity generated by the first solar power generation system 10 for self-use.

[0041] The second solar power generation system 20 includes a second solar cell string 22 having a plurality of second solar cell modules 21 electrically connected in series with each other, and a second power converter (PCS: power conditioner) 23 electrically connected to the second solar cell string 22. The second power converter 23 converts the DC power of the second solar cell string 22 into AC power.

[0042] In the case shown in Figure 1, the second solar cell string 22 is configured such that multiple second solar cell modules 21 are arranged side by side in the horizontal direction of the paper. There may be gaps (for example, a few millimeters) between adjacent second solar cell modules 21.

[0043] The second solar cell string 22 is configured such that multiple second solar cell modules 21 are electrically connected in series with each other, and is installed on the back side of the first solar cell module 11 so as to generate electricity using only indirect light, not direct sunlight, as described later. The physical arrangement of the multiple second solar cell modules 21 can be changed as appropriate. In the case shown in Figure 1, the second solar power generation system 20 is configured to have only one second solar cell string 22, but it is not limited to this configuration, and can also be configured to have a solar cell array with multiple second solar cell strings 22. In this case, the multiple second solar cell strings 22 can be electrically connected to each other using a junction box, and then electrically connected to the second power converter 23 via the junction box.

[0044] The second power converter 23 is a so-called power conditioner (PCS) equipped with an inverter. The second power converter 23 converts the DC power generated by the multiple second solar cell modules 21 into AC power and outputs it to the power grid. In other words, the second photovoltaic power generation system 20 is configured such that the power generated by the multiple second solar cell modules 21 is connected to the power grid of the power transmission and distribution company by the second power converter 23.

[0045] The second power converter 23 can be configured to control power using the Maximum Power Point Tracking (MPPT) method to maximize the power generated by all second solar cell strings 22 when the second photovoltaic power generation system 20 is configured to have multiple second solar cell strings 22.

[0046] Alternatively, the second power converter 23 may be constructed as part of the equipment itself and configured to utilize (self-consume) the electricity generated by the second solar power generation system 20.

[0047] Thus, the photovoltaic power generation system 1 is configured such that the first photovoltaic power generation system 10 and the second photovoltaic power generation system 20 are separate systems, and these two photovoltaic power generation systems are configured to operate in parallel.

[0048] The installation method for the photovoltaic power generation system according to this embodiment is characterized in that, when installing the photovoltaic power generation system 1 having the above configuration at the installation site, each first solar cell module 11 is installed to generate electricity by receiving total solar radiation including direct and indirect sunlight, and each second solar cell module 21 is installed on the back side of the first solar cell module 11 to generate electricity using only indirect sunlight. In other words, in the photovoltaic power generation system 1, the multiple second solar cell modules 21 are installed on the back side of the first solar cell module 11 to generate electricity using only indirect light that does not include direct sunlight.

[0049] Thus, in the photovoltaic power generation system 1 installed by the installation method of the photovoltaic power generation system according to this embodiment, the plurality of first solar cell modules 11 are installed so that they can generate electricity by receiving total solar radiation including direct and indirect sunlight, while the plurality of second solar cell modules 11 are installed on the back side of the first solar cell modules 11 so that they can generate electricity using only indirect sunlight. As a result, the plurality of second solar cell modules 21, which are installed on the back side of the first solar cell modules 11, can be installed without substantially expanding the installation area, thereby enabling the conversion of reflected sunlight reflected around the photovoltaic power generation system 1 into electricity, and thus increasing the conversion rate of solar energy to electricity per unit area of ​​the photovoltaic power generation system 1.

[0050] Furthermore, according to the installation method of the photovoltaic power generation system of this embodiment, by using an existing photovoltaic power generation system as the first photovoltaic power generation system 10, even if the power generated by the first photovoltaic power generation system 10 decreases due to the aging deterioration of the solar cell modules 11, etc., the power lost due to the aging deterioration of the solar cell modules 11 can be easily compensated for by the power generated by the multiple second solar cell modules 21 by installing multiple second solar cell modules 21 on the back side of the multiple first solar cell modules 11 whose power generation has decreased due to the aging deterioration of the solar cell modules 11.

[0051] Furthermore, in a solar power generation system 1 installed according to the installation method of the solar power generation system according to this embodiment, the first solar cell module 11 to the second solar cell module 21 can be replaced individually as they are. Therefore, if the power generation performance of either the first solar cell module 10 or the second solar cell module 21 deteriorates, the one whose power generation performance deterioration is acceptable can be used as is, and only the other one whose power generation performance deterioration is not acceptable can be replaced.

[0052] In the installation method of the photovoltaic power generation system and the photovoltaic power generation system 1 according to this embodiment, a crystalline silicon solar cell is used as the first solar cell module 11, and a transparent perovskite solar cell is used as the second solar cell module 21. The perovskite solar cell used as the second solar cell module 21 is not limited to a transparent type, but may also be an opaque type.

[0053] As shown in Figure 2, the first solar cell module 11 using a crystalline silicon solar cell has a configuration in which solar cells (power generation elements) 11a are arranged in a plane at regular intervals (for example, several millimeters). In the case shown in Figure 2, the solar cell module 11 has eight solar cells 11a arranged vertically and six solar cells arranged horizontally, giving it an overall elongated rectangular shape. For convenience, in Figure 2, only one solar cell 11a is labeled. A back sheet 11b is placed on the back side of the solar cell 11a, and the solar cell 11a is supported by a rectangular metal frame 11c outside the back sheet 11b. In the solar cell module 11, the area enclosed by the four corners A, B, C, and D of the rectangular area in which the solar cells 11a are arranged is the power generation area that generates electricity when it receives sunlight.

[0054] Each solar cell module 11, as illustrated in Figure 3 for one solar cell module 11, has an internal configuration consisting of three cell strings 11d, each containing 16 solar cells 11a arranged in two rows of eight and electrically connected in series, and three bypass diodes (BDs) 11e provided on the current path that bypasses the cell strings 11d, forming three clusters 11f, each cluster 11f being electrically connected in series with the others. In Figure 3, the thick solid line shows the path of the generated current of the first solar cell string 12. The current path enclosed by the dotted line in Figure 3 also consists of a generated current cable connecting the three bypass diodes 11e housed in a junction box (not shown) installed on the back of each first solar cell module 11 to each first solar cell module 11, and these are installed so as to be located on the back of the first solar cell module 11.

[0055] The bypass diode 11e is designed to bypass the cell strings 11d and prevent hot spots from occurring in the cell strings 11d. When sunlight is unevenly irradiated onto the cell strings 11d due to shading or other obstructions, causing the power generation of the cell strings 11d within the cluster 11f to decrease, the voltage across the portion of the cell string 11d that has relatively decreased becomes higher than the power generation voltage generated by the normally functioning portion of the cell string 11d within the same cluster 11f, and equals the forward voltage of the bypass diode 11e. Therefore, when sunlight is uniformly irradiated onto the entire normal solar cell module 11, the sum of the electromotive forces generated by each solar cell 11a will be greater than or equal to the forward voltage of the bypass diode 11e. As shown by the thick line in Figure 3, the power generation current will flow sequentially through each cell string 11d without passing through the bypass diode 11e.

[0056] The number of clusters 11f and the number of solar cells 11a constituting the solar cell module 11 can be changed as appropriate.

[0057] As shown in Figure 4, the second solar cell module 21 using a transparent perovskite solar cell is a rectangular sheet-like structure comprising a rectangular power generation region 21a and a non-power generation region 21b provided around the entire circumference outside the power generation region 21a.

[0058] As shown in Figure 5, the second solar cell module 21 using a transparent perovskite solar cell has a substrate 21c and a plurality of cells 21d provided on the substrate 21c. Each cell 21d has a configuration in which a transparent electrode 21e, an electron transport layer 21f, a perovskite power generation layer 21g, a hole transport layer 21h, and a back electrode 21i are stacked in this order.

[0059] The substrate 21c is made of a material that can be treated as transparent (absorbs almost no sunlight) in the wavelength range to which various solar cells are sensitive, such as synthetic resin materials like polyethylene naphthalate (PEN), which is a polymer film with a relatively high heat resistance temperature, or glass. When the substrate 21c is a polymer film, the solar cell module 21 can be made lighter and more flexible compared to when a glass substrate is used. On the other hand, when a glass substrate is used as the substrate 21c, it does not have flexibility, but it can withstand loads such as wind pressure.

[0060] For the transparent electrode 21e, for example, a transparent conductive film (ITO) can be used. For the electron transport layer 21f, for example, titanium dioxide (TiO2) can be used. Furthermore, for the perovskite power generation layer 21g, for example, an organic semiconductor material represented by the chemical formula CH3NH3Pbl3 can be used. Furthermore, the hole transport layer 21h has the function of moving holes generated by excitation by sunlight to the positive electrode, and for example, Spiro-OMeTAD can be used. Both the electron transport layer 21f and the hole transport layer 21h can be treated as transparent (with almost no sunlight absorption) in the wavelength range to which various solar cells are sensitive, similar to the substrate 21c. Furthermore, for the back electrode 21i, for example, a transparent conductive oxide (TCO) formed from transparent conductive glass (FTO: fluorine-doped tin oxide) can be used.

[0061] The second solar cell module 21, which uses a transparent perovskite solar cell, is formed through the following steps: multilayer deposition of a charge transport layer (hole transport layer 21h and electron transport layer 21f) and a perovskite power generation layer 21g on a patterned transparent electrode 21e layer on a substrate 21c; scribing to separate the charge transport layer and the perovskite power generation layer 21g; deposition of a back electrode 21i; and electrical series connection of cells 21d by electrode separation. The reason for separating the cells 21d from the transparent electrode 21e layer on the substrate 21c side and creating a series connection structure is to suppress the series resistance of the second solar cell module 21, as is commonly done in thin-film solar cells.

[0062] As shown by the thick arrows in Figure 5, when sunlight enters from the substrate 21c side and reaches the perovskite power generation layer 21g of cell 21d, the semiconductor properties of the perovskite power generation layer 21g generate charge carriers (electrons and holes) by photoexcitation. Electrons move to the electron transport layer 21f, and holes move to the hole transport layer 21h. The electrons then move through the electron transport layer 21f to the transparent electrode 21e on the substrate 21c side, and further to the negative electrode, where they combine with holes generated by the adjacent cell 21d. In this way, as shown by the thick arrows in Figure 5, the electrons generated by photoexcitation are successively transferred to the adjacent cell 21d, moving to the negative electrode side of the second solar cell module 21. Since the direction of the generated current is opposite to the direction of the electron flow, the generated current flows from the negative electrode side to the positive electrode side of the second solar cell module 21 as shown in Figure 5.

[0063] The power generation region 21a of the second solar cell module 21 is the region where the cells 21d of the second solar cell module 21 are located. On the other hand, the non-power generation region 21b of the second solar cell module 21 is the region of the substrate 21c in the second solar cell module 21 where the perovskite power generation layer 21g is not present. Therefore, since no power is generated in the non-power generation region 21b, there is no absorption of sunlight and it is light-transmitting.

[0064] Thus, the second solar cell module 21, which uses a transparent perovskite solar cell, employs transparent materials for both the positive and negative electrodes. As a result, the second solar cell module 21 is transparent and capable of transmitting sunlight.

[0065] The perovskite solar cell constituting the second solar cell module 21 may be one in which a metal such as gold or silver is used as the back electrode 21i.

[0066] Figure 6 shows one configuration of the arrangement of multiple first solar cell modules 11 and multiple second solar cell modules 21 in the photovoltaic power generation system 1 shown in Figure 1, and Figure 7 is a side view of the photovoltaic power generation system shown in Figure 6.

[0067] In Figures 6 and 7, the same reference numerals are used to indicate the components or parts corresponding to those mentioned above. In Figure 6, the top of the page is north, the bottom is south, the left side is west, and the right side is east.

[0068] In the photovoltaic power generation system 1 shown in Figure 6, the first photovoltaic power generation system 10 has a configuration in which a solar cell array has two first solar cell strings 12 arranged adjacent to each other in the east-west direction.

[0069] Of the two first solar cell strings 12, the first solar cell string 12 located on the west side has eight first solar cell modules 11 arranged in two upper and lower rows. These modules are electrically connected in series with adjacent modules in a counterclockwise direction, from the easternmost first solar cell module 11 in the upper row to the easternmost first solar cell module 11 in the lower row, thus forming one of the first solar cell strings 12. The easternmost first solar cell module 11 in the upper row and the easternmost first solar cell module 11 in the lower row are each connected to the first power converter 13. Similarly, the other first solar cell string 12 located on the east side also has eight first solar cell modules 11 arranged in two upper and lower rows. These modules are electrically connected in series with adjacent modules in a counterclockwise direction, from the westernmost first solar cell module 11 in the upper row to the westernmost first solar cell module 11 in the lower row, thus forming the other first solar cell string 12. The first solar cell module 11 located on the westernmost side of the upper row and the first solar cell module 11 located on the westernmost side of the lower row are each connected to the first power converter 13. This constitutes the first photovoltaic power generation system 10.

[0070] The power converter 13 may be directly connected to the multiple first solar cell strings 12, or it may be connected via a junction box (not shown).

[0071] As shown in Figure 7, the two first solar cell strings 12 are supported by a south support 30 and a north support 31, respectively, and are installed above the ground 32 at an angle such that the north side is higher than the south side.

[0072] In the photovoltaic power generation system 1 shown in Figure 6, the second photovoltaic power generation system 20 has eight second solar cell modules 21. The eight second solar cell modules 21 are arranged in a horizontal row from west to east and are electrically connected in series to form a second solar cell string 22. The two second solar cell modules 21 at each end are each connected to a second power converter 23, thereby forming the second photovoltaic power generation system 20.

[0073] The eight second solar cell modules 21 are each installed on the back side of the first solar cell modules 11, facing away from the first solar cell modules 11. In other words, the eight second solar cell modules 21 are each installed back-to-back with the first solar cell modules 11. More specifically, as shown in Figures 6 and 7, the eight second solar cell modules 21 are installed on the back side of the corresponding first solar cell modules 11 of the eight first solar cell modules 11 that are positioned on the north side, straddling the two first solar cell strings 12, facing away from the first solar cell modules 11. As a method for installing the second solar cell modules 21 back-to-back with the first solar cell modules 11, any appropriate method or structure can be used, such as fixing the first solar cell modules 11 and the second solar cell modules 21 together with clamps.

[0074] For the first solar cell module 11, it is preferable to use an opaque type, and crystalline silicon solar cells or multi-stage perovskite solar cells including an opaque type at the bottom are applicable. For the second solar cell module 21, it is preferable to use a perovskite solar cell that generates power efficiently even in low light conditions.

[0075] With this arrangement, each first solar cell module 11 generates electricity by receiving direct sunlight, and because each first solar cell module 11 is opaque, each second solar cell module 21 can generate electricity using only indirect sunlight, such as reflected light reflected from a structure 33, such as a wall adjacent to the solar power generation system 1, and the ground 32.

[0076] In this configuration, the second solar cell module 21 is positioned on the back side of the first solar cell module 11, with a bias toward the north. This allows it to receive more indirect sunlight, such as reflected light from the structure 33 adjacent to the solar power generation system 1 and the ground 32, thereby enabling more efficient power generation.

[0077] The photovoltaic power generation system 1 is not limited to a configuration in which eight second solar cell modules 21 are installed back-to-back with the first solar cell module 11, as shown in Figure 7. Alternatively, as shown in Figure 8, the eight second solar cell modules 21 may be installed on the rear side of the first solar cell module 11, using the north support column 31 to install them perpendicular to the ground 32 and facing north.

[0078] In this arrangement, each first solar cell module 11 generates electricity by receiving direct sunlight, and each second solar cell module 21, since it faces north, can generate electricity using only indirect sunlight, such as reflected light reflected by a structure 33 adjacent to the solar power generation system 1. Furthermore, in a ground-mounted solar power plant with multiple solar power generation systems, multiple solar cell arrays are installed in parallel in the north-south direction. As a result, the first solar cell modules 11 of the solar cell array adjacent to the north receive reflected light from direct sunlight, and the second solar cell modules 21 of the solar cell array to the south receive reflected light from direct sunlight, allowing the second solar power generation system 20 to efficiently utilize the reflected light from direct sunlight for power generation. Therefore, the conversion rate of solar energy to electricity per unit area can be further improved.

[0079] As shown in Figures 9 and 10 as modified examples, the installation method of the photovoltaic power generation system according to this embodiment can also be configured such that the third photovoltaic power generation system 40, which comprises a third solar cell string 42 having a plurality of transparent third solar cell modules 41 electrically connected in series with each other, and a third power converter 43 electrically connected to the third solar cell string 42, is installed with the third solar cell modules 41 stacked on top of the first solar cell modules 11 so that each first solar cell module 11 generates electricity from sunlight that passes through the third solar cell modules 41, and the second solar cell modules 21 are installed stacked below the first solar cell modules 11 so that they face away from the first solar cell modules 11. In other words, the photovoltaic power generation system 1 according to this embodiment further comprises a third photovoltaic power generation system 40 comprising a third solar cell string 42 having a plurality of transparent third solar cell modules 41 electrically connected in series with each other, and a third power converter 43 electrically connected to the third solar cell string 42. The third solar cell modules 41 are installed on top of the first solar cell modules 11 so that each first solar cell module 11 generates electricity from sunlight transmitted through the third solar cell modules 41, and each second solar cell module 21 is installed on top of the first solar cell modules 11 so that it faces away from the first solar cell modules 11.

[0080] In this modified photovoltaic power generation system 1, the third solar cell string 42 is configured such that a plurality of transparent third solar cell modules 41 are arranged above a plurality of first solar cell modules 11, side by side in the horizontal direction of the paper.

[0081] As described above, in the modified photovoltaic installation method and photovoltaic system 1, multiple third solar cell strings 42 are arranged in stacks above multiple first solar cell modules 11, such that each first solar cell module 11 generates electricity from sunlight that passes through the transparent third solar cell module 41. In other words, a second solar cell string 22 is installed in stacks above the first solar cell string 12.

[0082] Therefore, in a photovoltaic power generation system 1 installed by the modified installation method, multiple transparent third solar cell modules 41 can each generate electricity by receiving direct sunlight, multiple first solar cell modules 11 can each generate electricity from sunlight that has passed through the transparent third solar cell modules 41 without being generated by the transparent third solar cell modules 41, and multiple second solar cell modules 21 can each generate electricity from reflected sunlight, i.e., indirect sunlight, that has been reflected around the photovoltaic power generation system 1. Thus, the conversion rate of solar energy to electricity per unit area of ​​the photovoltaic power generation system 1 can be further increased.

[0083] In this modified example, it is preferable to use a transparent perovskite solar cell as the third solar cell module 41, as shown in Figures 4 and 5, but other structures of transparent solar cell modules may also be used.

[0084] In this modified example, various types of solar cells can be used as the first solar cell module 11 of the first photovoltaic power generation system 10, such as transparent or opaque perovskite solar cells, crystalline silicon solar cells, and CIS solar cells.

[0085] Furthermore, in this modified example, various types of solar cells can be used as the second solar cell module 21 of the second photovoltaic power generation system 20, such as transparent or opaque perovskite solar cells, crystalline silicon solar cells, and CIS solar cells.

[0086] The present invention is not limited to the embodiments described above, and it goes without saying that various modifications are possible without departing from the spirit of the invention. [Explanation of Symbols]

[0087] 1. Solar power generation system 10. The first solar power generation system 11. First solar cell module 11a solar cell 11b Backseat 11c metal frame 11d Cell String 11e Bypass Diode 11f cluster 12. First solar cell string 13. First power converter 20. Second solar power generation system 21. Second solar cell module 21a Power generation area 21b Non-power generation area 21c circuit board 21d cell 21e transparent electrode 21f Electron transport layer 21g perovskite power generation layer 21h Hole transport layer 21i back electrode 22 Second solar cell string 23. Second power converter 30 South pillar 31 North pillar 32 Ground 33 Structures 40. The third solar power generation system 41. Third solar cell module 42 Third Solar String 43. Third power converter A corner B corner C corner D corner

Claims

1. A first photovoltaic power generation system comprising a first solar cell string having a plurality of first solar cell modules electrically connected in series with respect to each other, and a first power converter electrically connected to the first solar cell string, A second photovoltaic power generation system comprising a second solar cell string having a plurality of second solar cell modules electrically connected in series with respect to each other, and a second power converter electrically connected to the second solar cell string, In a photovoltaic power generation system having, A method for installing a solar power generation system, characterized in that each of the second solar cell modules is installed on the back side of the first solar cell module so as to generate electricity using only indirect sunlight.

2. The method for installing a photovoltaic power generation system according to claim 1, wherein the second solar cell module is a perovskite solar cell.

3. A method for installing a photovoltaic power generation system according to claim 1 or 2, comprising a third solar cell string having a plurality of transparent third solar cell modules electrically connected in series with each other, and a third power converter electrically connected to the third solar cell string, wherein the third solar cell modules are installed on top of the first solar cell modules and each second solar cell module is installed on top of the first solar cell modules so that each of the first solar cell modules generates electricity from sunlight transmitted through the third solar cell modules, and each of the second solar cell modules is installed on top of the first solar cell modules so that it faces away from the first solar cell modules.

4. A first photovoltaic power generation system comprising a first solar cell string having a plurality of first solar cell modules electrically connected in series with respect to each other, and a first power converter electrically connected to the first solar cell string, A second photovoltaic power generation system comprising a second solar cell string having a plurality of second solar cell modules electrically connected in series with respect to each other, and a second power converter electrically connected to the second solar cell string, A solar power generation system having, A photovoltaic power generation system characterized in that each of the second solar cell modules is installed on the back side of the first solar cell module so as to generate electricity solely from indirect sunlight.

5. The photovoltaic power generation system according to claim 4, wherein the second solar cell module is a perovskite solar cell.

6. The third photovoltaic power generation system further comprises a third solar cell string having a plurality of transparent third solar cell modules electrically connected in series with respect to each other, and a third power converter electrically connected to the third solar cell string. The photovoltaic power generation system according to claim 4 or 5, wherein the third solar cell module is installed on top of the first solar cell module so that each of the first solar cell modules generates electricity from sunlight transmitted through the third solar cell module, and each of the second solar cell modules is installed on top of the first solar cell module so that it faces away from the first solar cell module.

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