Photovoltaic power generation system installation method and photovoltaic power generation system

Abstract

To provide a photovoltaic power generation system installation method and a photovoltaic power generation system, capable of improving a conversion rate per unit area from solar energy to power and capable of easily compensating power reduced by long-term deterioration and the like.SOLUTION: Provided are a photovoltaic power generation system installation method and a photovoltaic power generation system 1, the photovoltaic power generation system 1 including: a first photovoltaic power generation system 10 comprising a first solar cell string 12 comprising a first solar cell module 11 and a first power conversion device 13; and a second photovoltaic power generation system 20 comprising a second solar cell string 22 comprising a transmission type second solar cell module 21 and a second power conversion device 23, the method including superposing and installing the second solar cell string 22 above the first solar cell string 12 so that the first solar cell module 11 generates power using sunlight transmitted through the second solar cell module 21.SELECTED DRAWING: Figure 1

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 technology]

[0002] A conventional solar power generation system includes a solar cell string having a plurality of solar cell modules electrically connected in series with each other, and a power conversion device (PCS: power conditioner) electrically connected to the solar cell string, and is configured to interconnect the generated power with the power grid of a power transmission and distribution company via the power conversion device. In such a solar power generation system, the plurality of solar cell modules are installed so that they do not overlap each other vertically.

[0003] In this type of solar power generation system, the power generation decreases due to the deterioration of the solar cell module over time, etc. Because solar cell modules are constructed by electrically joining materials with different thermal expansion coefficients, such as semiconductors and metals, thermal stress caused by repeated changes in temperature day and night or seasonally will gradually reduce the power generation capacity over the long term. In addition, components may be suddenly damaged by lightning strikes, storms, etc., and these factors will inevitably lead to a power generation failure of the solar cell module as a whole.

[0004] Meanwhile, new solar cells that use perovskite crystals as the power generation layer have been developed in recent years (see, for example, Non-Patent Document 1). Perovskite solar cells can be fabricated, for example, by a coating process or printing process on a resin substrate, which allows for lower manufacturing costs compared to silicon-based solar cells. In addition, products that are lighter and more flexible than silicon-based solar cells can also be fabricated, so they are expected to be used in a variety of applications. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] Tsutomu Miyasaka, "The emergence of perovskite solar cells," Modern Chemistry, Tokyo Kagaku Dojin Co., Ltd., February 18, 2014, March 2014 issue, pp. 24-32 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in a solar power generation system installed using conventional installation methods, the generated power supplied to the power conversion device from multiple solar cell modules is limited by the energy conversion efficiency of each solar cell module, so regardless of the type of solar cell module used, there was a problem in that the solar energy conversion rate to electricity per unit area (energy utilization rate) of the solar power generation system could not be improved using the solar cell module as it was.

[0007] Furthermore, when the power generated by an existing solar power generation system decreases due to aging or other reasons of the solar cell modules, there is a problem in that it is difficult to compensate for the decrease in power.

[0008] The present invention has been proposed in view of the above-mentioned problems, and its object 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 loss of electricity due to deterioration over time, etc. [Means for solving the problem]

[0009] A method for installing a solar power generation system according to the present invention includes a first solar power generation system including a first solar cell string having a plurality of first solar cell modules electrically connected in series with each other and a first power conversion device electrically connected to the first solar cell string, and a second solar power generation system including a second solar cell string having a plurality of transparent second solar cell modules electrically connected in series with each other and a second power conversion device electrically connected to the second solar cell string, and is characterized in that the second solar cell string is installed above the first solar cell string so that each of the first solar cell modules generates power using sunlight that has passed through the second solar cell module.

[0010] In the installation method of the solar power generation system of the present invention, in the above configuration, it is preferable that the first solar cell module has a solar light absorption sensitivity in a predetermined wavelength range, and the second solar cell module has a solar light absorption sensitivity greater than that of the first solar cell module in at least a part of the wavelength range.

[0011] In the method for installing a photovoltaic power generation system of the present invention, in the above configuration, it is preferable that a crystalline silicon solar cell is used as the first solar cell module, and a transparent perovskite solar cell is used as the second solar cell module.

[0012] In the installation method for a solar power generation system of the present invention, in the above configuration, it is preferable that the second solar cell module is a rectangular plate-shaped module having a rectangular power generation area and a non-power generation area provided around the entire periphery outside the power generation area, and that the multiple second solar cell modules are arranged so that the power generation areas of adjacent second solar cell modules are connected to each other when viewed from a direction perpendicular to the second solar cell modules.

[0013] In the installation method for a solar power generation system of the present invention, in the above configuration, it is preferable that a third solar power generation system including a third solar cell string having a plurality of third solar cell modules electrically connected in series with each other, and a third power conversion device electrically connected to the third solar cell string, is installed by stacking the third solar cell string below the first solar cell string so that each of the third solar cell modules faces away from the first solar cell modules.

[0014] The solar power generation system of the present invention is a solar power generation system having: a first solar cell string having a plurality of first solar cell modules electrically connected in series with each other; and a first power conversion device electrically connected to the first solar cell string; and a second solar cell string having a plurality of transparent second solar cell modules electrically connected in series with each other; and a second power conversion device electrically connected to the second solar cell string, characterized in that the second solar cell string is installed above the first solar cell string so that each of the first solar cell modules generates power using sunlight that has passed through the second solar cell module.

[0015] In the solar power generation system of the present invention, in the above configuration, it is preferable that the first solar cell module has a solar light absorption sensitivity in a predetermined wavelength range, and the second solar cell module has a solar light absorption sensitivity greater than that of the first solar cell module in at least a portion of the wavelength range.

[0016] In the solar power generation system of the present invention having the above configuration, it is preferable that the first solar cell module is a crystalline silicon solar cell, and the second solar cell module is a transparent perovskite solar cell.

[0017] In the solar power generation system of the present invention, in the above configuration, it is preferable that the second solar cell module is a rectangular plate having a rectangular power generation area and a non-power generation area arranged around the entire periphery outside the power generation area, and that the multiple second solar cell modules are arranged so that the power generation areas of adjacent second solar cell modules are connected to each other when viewed from a direction perpendicular to the second solar cell modules.

[0018] In the above configuration, the solar power generation system of the present invention preferably further includes a third solar power generation system including a third solar cell string having a plurality of third solar cell modules electrically connected in series with each other, and a third power conversion device electrically connected to the third solar cell string, and the third solar cell string is preferably installed below the first solar cell string in a stacked manner so that each of the third solar cell modules faces away from the first solar cell modules. [Effects of the Invention]

[0019] 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 loss of electricity due to deterioration over time, etc. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a diagram showing an outline of a configuration of a photovoltaic power generation system according to a first embodiment, which is installed by a method for installing a photovoltaic power generation system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing the configuration of the first solar cell module shown in FIG. [Figure 3] FIG. 2 is a diagram showing a configuration of a first solar cell string shown in FIG. [Figure 4] FIG. 2 is a diagram showing the configuration of the second solar cell module shown in FIG. [Figure 5]FIG. 5 is a diagram showing a cross-sectional structure of the second solar cell module shown in FIG. [Figure 6] 2 is a diagram showing one embodiment of the arrangement of a plurality of first solar cell modules and a plurality of second solar cell modules in the solar power generation system shown in FIG. 1. FIG. [Figure 7] 7 is a diagram showing one embodiment of the arrangement of the plurality of first solar cell modules and the plurality of second solar cell modules shown in FIG. 6, as viewed from the arrow A in FIG. 6. FIG. [Figure 8] 10A and 10B are diagrams showing an embodiment of a method for installing and fixing a second solar cell string above a first solar cell string. [Figure 9] FIG. 1 is a diagram showing the relationship between the irradiance of the sunlight spectrum at each wavelength and the relative sensitivity of light absorption of various solar cells. [Figure 10] FIG. 10 is a diagram illustrating a schematic configuration of a solar power generation system according to a modified example. [Figure 11] FIG. 10 is a diagram illustrating a schematic configuration of a solar power generation system according to another modified example. [Figure 12] 12 is a diagram showing one embodiment 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 solar power generation system according to another modified example shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0021] A method for installing a solar power generation system according to the present invention includes a first solar power generation system including a first solar cell string having a plurality of first solar cell modules electrically connected in series with each other, and a first power conversion device electrically connected to the first solar cell string and converting DC power from the first solar cell string into AC power, and a second solar cell string having a plurality of transparent second solar cell modules electrically connected to the second solar cell string and a second power conversion device electrically connected to the second solar cell string and converting DC power from the second solar cell string into AC power, wherein the second solar cell string is installed above the first solar cell string so that each of the first solar cell modules generates power using sunlight that has passed through the second solar cell module.

[0022] Furthermore, the solar power generation system of the present invention is a solar power generation system having: a first solar cell string having a plurality of first solar cell modules electrically connected in series with each other; and a first power conversion device electrically connected to the first solar cell string; and a second solar cell string having a plurality of transparent second solar cell modules electrically connected in series with each other; and a second power conversion device electrically connected to the second solar cell string, wherein the second solar cell string is installed above the first solar cell string so that each of the first solar cell modules generates power using sunlight that has passed through the second solar cell module.

[0023] The solar power generation system of the present invention can be installed by the method for installing a solar power generation system of the present invention.

[0024] As the first solar cell module, various types of solar cells can be used as long as they are capable of receiving sunlight and generating electricity. Furthermore, the first solar cell string includes a plurality of first solar cell modules electrically connected in series, and the arrangement of the plurality of first solar cell modules can be set appropriately as long as each first solar cell module is configured to generate electricity using sunlight that has passed through the second solar cell module.

[0025] As the second solar cell module, various types of solar cells can be used as long as they are capable of receiving sunlight and generating electricity and are transparent, allowing a portion of the received sunlight to pass through. Also, as long as the second solar cell string is configured to include multiple transparent second solar cell modules electrically connected in series, the arrangement of each second solar cell module can be set appropriately.

[0026] The first solar cell module and the second solar cell module may be the same as each other in shape, size, number, and power generation performance, or may be different from each other.

[0027] Furthermore, the first solar power generation system may be one that has already been installed at the time the second solar power generation system is installed, or may be one that is newly installed at the time the second solar power generation system is installed.

[0028] According to the installation method for a solar power generation system or the solar power generation system of the present invention, a plurality of transparent second solar cell modules receive sunlight and generate electricity, and a plurality of first solar cell modules can each generate electricity using sunlight that has passed through the transparent second solar cell module, thereby increasing the solar energy conversion rate to electricity per unit area of ​​the solar power generation system.

[0029] Furthermore, according to the solar power generation system installation method or solar power generation system of the present invention, when the power generation of an existing solar power generation system decreases due to deterioration over time of the solar cell modules, etc., by installing multiple transparent second solar cell modules on top of multiple first solar cell modules whose power generation has decreased due to deterioration over time, etc., the power reduction due to deterioration over time, etc. can be easily compensated for by the power generation of the multiple second solar cell modules.

[0030] Furthermore, according to the solar power generation system installation method or solar power generation system of the present invention, the existing solar power generation system can be used to its performance limits, and after use of the existing solar power generation system has ceased, the existing solar power generation system can continue to be used as the substrate for a new solar power generation system installed above it. This means that the cost of removing the existing solar power generation system can be reserved, and the revenue from power generation by the upper solar power generation system can be used to cover the cost of replacing the existing solar power generation system.

[0031] Furthermore, according to the installation method for a solar power generation system and the solar power generation system of the present invention, the first solar cell module and the second solar cell module can be replaced individually, so that if the power generation performance of either the first solar cell module or the second solar cell module deteriorates, it is possible to continue using either the first solar cell module or the second solar cell module whose power generation performance deterioration is tolerable, and only replace the other solar cell module whose power generation performance deterioration is not tolerable, eliminating the need to replace the entire solar cell module as in tandem solar cell modules (solar cells in which different types of power generation layers are integrally molded). Therefore, according to the installation method for a solar power generation system and the solar power generation system of the present invention, it is possible to reduce the maintenance costs of the solar power generation system.

[0032] The present invention will now be described in more detail with reference to the accompanying drawings.

[0033] 1 shows a solar power generation system 1 according to an embodiment of the present invention, which is installed by a method for installing a solar power generation system according to an embodiment of the present invention. The solar power generation system 1 includes a first solar power generation system 10 and a second solar power generation system 20.

[0034] The first solar power generation system 10 includes a first solar cell string 12 having a plurality of first solar cell modules 11 electrically connected in series with each other, and a first power conversion device (PCS: power conditioner) 13 electrically connected to the first solar cell string 12. The first power conversion device 13 converts DC power of the first solar cell string 12 into AC power.

[0035] 1, the first solar cell string 12 is configured such that a plurality of first solar cell modules 11 are arranged in parallel in the horizontal direction of the page. There may be a gap (for example, about several mm) between adjacent first solar cell modules 11.

[0036] Note that the arrangement of the first solar cell string 12 can be changed as appropriate as long as the first solar cell modules 11 are electrically connected in series to each other. In the case shown in Fig. 1, the first solar power generation system 10 is configured to include only one first solar cell string 12, but this is not limiting and the first solar cell system 10 can also be configured to include a solar cell array including 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 electrically connected to the first power conversion device 13 via the junction box.

[0037] The first power conversion device 13 is a so-called power conditioner (PCS) equipped with an inverter. The first power conversion device 13 converts DC power generated by the plurality of first solar cell modules 11 into AC power and outputs it to the power grid. That is, the first solar power generation system 10 is configured such that the first power conversion device 13 interconnects the power generated by the plurality of first solar cell modules 11 with the power grid of the power transmission and distribution company.

[0038] In addition, when the first solar power generation system 10 is configured to have a plurality of first solar cell strings 12, the first power conversion device 13 can be configured to control power using an MPPT (Maximum Power Point Tracking) method to maximize the power generation of all the first solar cell strings 12.

[0039] The second solar power generation system 20 includes a second solar cell string 22 including a plurality of sunlight-transmitting type (hereinafter simply referred to as "transmitting type") second solar cell modules 21 electrically connected in series with each other, and a second power conversion device (PCS: power conditioner) 23 electrically connected to the second solar cell string 22. The second power conversion device 23 converts DC power of the second solar cell string 22 into AC power.

[0040] In the case shown in FIG. 1, the second solar cell string 22 is configured such that a plurality of second transparent solar cell modules 21 are arranged in parallel in the horizontal direction of the page.

[0041] The second solar cell string 22 includes a plurality of transparent second solar cell modules 21 electrically connected in series with each other, and as described below, the arrangement of the plurality of transparent second solar cell modules 21 can be changed as appropriate as long as each first solar cell module 11 is disposed above the first solar cell string 11 so as to generate power using sunlight transmitted through the transparent second solar cell modules 21. In the example shown in FIG. 1 , the second solar power generation system 20 includes only one second solar cell string 22, but the present invention is not limited to this and the second solar cell system 20 may include a solar cell array including a plurality of second solar cell strings 22. In this case, the plurality of second solar cell strings 22 may be electrically connected to each other using a junction box and electrically connected to the second power conversion device 23 via the junction box.

[0042] The second power conversion device 23 is a so-called power conditioner (PCS) equipped with an inverter. The second power conversion device 23 converts DC power generated by the plurality of second solar cell modules 21 into AC power and outputs it to the power grid. That is, the second solar power generation system 20 is configured such that the second power conversion device 23 interconnects the power generated by the plurality of second solar cell modules 21 with the power grid of the power transmission and distribution company.

[0043] In addition, when the second solar power generation system 20 is configured to include a plurality of second solar cell strings 22, the second power conversion device 23 can be configured to control power using an MPPT (Maximum Power Point Tracking) method to maximize the power generation of all second solar cell strings 22.

[0044] In this way, the solar power generation system 1 is configured such that the first solar power generation system 10 and the second solar power generation system 20 are solar power generation systems on separate systems, and both solar power generation systems are operated in parallel.

[0045] The installation method for the solar power generation system according to this embodiment is characterized in that, when installing the solar power generation system 1 having the above-described configuration at an installation location, the second solar cell string 22 is installed above the first solar cell string 12 so that each first solar cell module 11 generates power from sunlight that has transmitted through the transparent second solar cell module 21. That is, in the solar power generation system 1 according to one embodiment of the present invention, the second solar cell string 22 is installed above the first solar cell string 12 so that each first solar cell module 11 generates power from sunlight that has transmitted through the transparent second solar cell module 21.

[0046] Therefore, in the solar power generation system 1 installed using the solar power generation system installation method of this embodiment, the multiple second solar cell modules 21 can each receive sunlight and generate electricity, and the multiple first solar cell modules 11 can each generate electricity using sunlight that is not generated by the transparent second solar cell modules 12 but that has passed through the transparent second solar cell modules 12, thereby increasing the conversion rate of solar energy to electricity per unit area of ​​the solar power generation system 1.

[0047] Furthermore, according to the installation method for a solar power generation system according to this embodiment, by using an existing solar power generation system as the first solar power generation system 10, when the power generation output of the first solar power generation system 10 decreases due to aging degradation of the solar cell modules 11 or the like, it is possible to install a second solar cell string 22 including a plurality of transparent second solar cell modules 21 on the first solar cell string 12 including a plurality of first solar cell modules 11 whose power generation output has decreased due to aging degradation or the like. This makes it possible to easily compensate for the power reduction due to aging degradation of the solar cell modules 11 by the power generation of the plurality of second solar cell modules 21.

[0048] Furthermore, according to the installation method for the photovoltaic power generation system according to this embodiment, the first photovoltaic power generation system 10, which is an existing photovoltaic power generation system, can be used up to its performance limit, and after use of the existing first photovoltaic power generation system 10 is finished, the first photovoltaic power generation system 10 can continue to be used as a substrate for a new second photovoltaic power generation system 20 installed on the upper level. This allows the removal cost of the first photovoltaic power generation system 10 to be reserved, and the power generation revenue of the second photovoltaic power generation system 20 on the upper level to be applied to the renewal cost of the existing first photovoltaic power generation system 10.

[0049] Furthermore, in the solar power generation system 1 installed by the solar power generation system installation method according to this embodiment, the first solar cell module 11, the second solar cell module 21, and so on can be replaced individually. Therefore, if the power generation performance of either the first solar cell module 10 or the second solar cell module 21 deteriorates, it is possible to continue using the one of the first solar cell module 11 and the second solar cell module 21, whose power generation performance deterioration is tolerable, and replace only the other, whose power generation performance deterioration is not tolerable. This eliminates the need to replace the entire solar cell module, as is the case with tandem solar cell modules (solar cells in which different types of power generation layers are integrally molded), and reduces the maintenance costs of the solar power generation system 1.

[0050] In the installation method for a solar power generation system and the solar power generation system 1 according to this embodiment, a solar cell module having solar light absorption sensitivity in a predetermined wavelength range is used as the first solar cell module 11, and a solar cell module having solar light absorption sensitivity greater than that of the first solar cell module 11 in at least a part of the predetermined wavelength range is used as the second solar cell module 21. More specifically, in the installation method for a solar power generation system and the solar 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.

[0051] As shown in FIG. 2, a first solar cell module 11 using crystalline silicon solar cells has a configuration in which solar cell cells (power generation elements) 11a are aligned on a plane at regular intervals (for example, several mm). In the case shown in FIG. 2, the solar cell module 11 has eight solar cell cells 11a aligned in the vertical direction and six solar cell cells aligned in the horizontal direction on the page, giving the solar cell module 11 a vertically long rectangular shape as a whole. For convenience, only one solar cell 11a is labeled in FIG. 2. A back sheet 11b is arranged on the back side of the solar cell 11a, and the solar cell 11a is supported by a rectangular metal frame 11c on the outside of the back sheet 11b. In the solar cell module 11, the area surrounded by the four corners (A, B, C, C) of the rectangular area in which the solar cell cells 11a are aligned is the power generation area that generates electricity by receiving sunlight.

[0052] As shown in Fig. 3 for one solar cell module 11, each solar cell module 11 has an internal configuration including three cell strings 11d, each of which has 16 solar cells 11a arranged in two rows of eight cells each and is electrically connected in series, and three clusters 11f, each of which includes three bypass diodes (BD) 11e provided on a current path bypassing the cell strings 11d, and the clusters 11f are electrically connected in series with each other. In Fig. 3, a thick solid line indicates the path of the generated current of the first solar cell string 12. In Fig. 3, the current path surrounded by a dotted line includes three bypass diodes 11e housed in a junction box (not shown) installed on the back of each first solar cell module 11 and generated current cables connecting 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.

[0053] The bypass diode 11e operates when the voltage across a portion of the cell string 11d in cluster 11f where the amount of power generated by the cell string 11d is relatively low due to, for example, uneven sunlight irradiation on the cell string 11d caused by a shadow or obstruction becomes higher than the voltage generated by the portion of the cell string 11d in the same cluster 11f that is generating power normally, and becomes equal to the forward voltage of the bypass diode 11e, causing the generated current to bypass the cell string 11d and avoid the occurrence of hot spots in the cell string 11d. Therefore, when sunlight is uniformly irradiated across the entire normal solar cell module 11, the total electromotive force generated by the power generation of each solar cell 11a exceeds the forward voltage of the bypass diode 11e, and the generated current flows sequentially through each cell string 11d without passing through the bypass diode 11e, as shown by the bold line in Figure 3.

[0054] The number of clusters 11f constituting the solar cell module 11 and the number of solar cell cells 11a constituting the clusters 11f can be changed as appropriate.

[0055] As shown in Figure 4, the second solar cell module 21 using a transparent perovskite solar cell is in the form of a rectangular sheet having a rectangular power generation area 21a and a non-power generation area 21b provided around the entire periphery outside the power generation area 21a.

[0056] 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 laminated in this order.

[0057] Substrate 21c is formed of a material that can be treated as transparent (has almost no solar light absorption) in the wavelength range to which various solar cells are sensitive, such as glass or a synthetic resin material such as polyethylene naphthalate (PEN), which is a polymer film with a relatively high heat resistance. When substrate 21c is a polymer film, solar cell module 21 can be made lighter and more flexible than when a glass substrate is used. On the other hand, when a glass substrate is used as substrate 21c, it is not flexible but can withstand loads such as wind pressure.

[0058] The transparent electrode 21e can be, for example, a transparent conductive film (ITO). The electron transport layer 21f can be, for example, titanium oxide (TiO2). The perovskite power generation layer 21g can be, for example, an organic semiconductor material represented by the chemical formula CH3NH3Pb13. The hole transport layer 21h has the function of transporting holes generated by excitation by sunlight to the positive electrode, and can be, for example, Spiro-OMeTAD. Like the substrate 21c, both the electron transport layer 21f and the hole transport layer 21h can be treated as transparent (they absorb almost no sunlight) in the wavelength range to which various solar cells are sensitive. The back electrode 21i can be, for example, a transparent conductive oxide (TCO) formed of transparent conductive glass (FTO: fluorine-doped tin oxide).

[0059] The second solar cell module 21 using transparent perovskite solar cells is formed, for example, through the steps of depositing a multilayer film of a charge transport layer (hole transport layer 21h and electron transport layer 21f) and a perovskite power generation layer 21g on a layer of transparent electrode 21e patterned on a substrate 21c, scribing to separate the charge transport layer and the perovskite power generation layer 21g, depositing a back electrode 21i, and separating the electrodes to electrically connect the cells 21d in series. The reason for separating the cells 21d from the layer of transparent electrode 21e on the substrate 21c side by scribing to form a series-connected structure is to suppress the series resistance of the second solar cell module 21, as is commonly used in thin-film solar cells.

[0060] As shown by the bold arrows in Figure 5, when sunlight enters from the substrate 21c side and reaches the perovskite power generation layer 21g of the cell 21d, charge carriers (electrons and holes) are generated by photoexcitation due to the semiconducting properties of the perovskite power generation layer 21g. The electrons then move to the electron transport layer 21f, and the 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, then to the negative electrode, where they combine with holes generated by the adjacent cell 21d. In this way, as shown by the bold arrows in Figure 5, the electrons generated by photoexcitation are transferred to the adjacent cell 21d one after another, thereby moving toward the negative electrode of the second solar cell module 21. Because the direction of the generated current is opposite to the flow of electrons, the generated current flows from the negative electrode to the positive electrode of the second solar cell module 21 shown in Figure 5.

[0061] The power generating region 21a of the second solar cell module 21 is a region where the cells 21d of the second solar cell module 21 are present. On the other hand, the non-power generating region 21b of the second solar cell module 21 is a region formed by the substrate 21c where the perovskite power generating layer 21g is not present in the second solar cell module 21. Therefore, the non-power generating region 21b does not generate power and does not absorb sunlight, so it is translucent.

[0062] In this way, the second solar cell module 21 using a transparent perovskite solar cell uses transparent electrodes for both the positive and negative electrodes, making the second solar cell module 21 a transparent type that can transmit sunlight.

[0063] Both the power generating region 21a and the non-power generating region 21b of the second solar cell module 21 are translucent, but the power generating region 21a absorbs sunlight in the light absorption wavelength range of the perovskite solar cell, while the non-power generating region 21b simply transmits sunlight, so the power generating region 21a and the non-power generating region 21b have different sunlight transmittances.

[0064] Even if the perovskite solar cell constituting the second solar cell module 21 uses a metal such as gold or silver as the back electrode 21i, it can be used as a second solar cell module 21 having translucency as long as the back electrode 21i has a film thickness and structure that allows it to transmit sunlight.

[0065] When transparent perovskite solar cells having the above-described configuration are used as the multiple second solar cell modules 21, it is preferable to arrange the multiple second solar cell modules 21 so that the power generation regions 21a of adjacent second solar cell modules 21 are connected to each other without any gaps when viewed from a direction perpendicular to the second solar cell modules 21 (a direction perpendicular to the paper surface in Figure 7).

[0066] More specifically, as shown in FIGS. 6 and 7 , the second solar cell modules 21 are installed so that the power generating regions 21a of adjacent second solar cell modules 21 are contiguous, overlapping each other at the outer periphery including the non-power generating regions 21b. When the second solar cell modules 21 are arranged in multiple vertical tiers, the second solar cell modules 21 are installed so that the power generating regions 21a of adjacent second solar cell modules 21 are contiguous, overlapping each other at the outer periphery including the non-power generating regions 21b. This allows the entire power generating region formed by the continuous power generating regions 21a of the multiple second solar cell modules 21 to cover the entire power generating regions of the multiple first solar cell modules 11 included in the first solar cell string 12. Note that the region of the first solar cell module 11 covered by the entire power generating region formed by the continuous power generating regions 21a of the multiple second solar cell modules 21 may include a non-power generating region.

[0067] With this configuration, sunlight that has passed through the plurality of second solar cell modules 21 can be uniformly, i.e., uniformly irradiated onto each of the plurality of first solar cell modules 11. Therefore, even if the configuration shown in Fig. 3 is adopted as the first solar cell string 12, hot spots are not generated in the cell string 11d of the first solar cell modules 11 that constitute the first solar cell string 12, and the first solar power generation system 10 can be operated efficiently.

[0068] In addition, if the power generation area 21a of the second solar cell module 21 is larger than the power generation area of ​​the first solar cell module 11, the first solar cell module 11 can be installed so that the entire power generation area of ​​the first solar cell module 11 is within the range of the power generation area 21a of the second solar cell module 21.

[0069] FIG. 8 shows one example of a method for installing and fixing a second solar cell string 22 above a first solar cell string 12. As shown in FIG. 8, the first solar cell module 11 using crystalline silicon solar cells has a superstrate structure. That is, the first solar cell module 11 has a support plate 11g formed of a transparent substrate such as glass on the light-receiving side. The cell string 11d is encapsulated inside the support plate 11g using a transparent filler material (not shown) and a back sheet 11h, and the periphery is then framed by a frame 11i such as an aluminum frame. The frame 11i corresponds to the metal frame 11c described above. The transparent substrate constituting the support plate 11g can be, for example, heat-strengthened white glass, which is suitable for silicon-based solar cells that utilize long-wavelength light. In this embodiment, the second solar cell string 22 is placed above the first solar cell string 12 so that the non-power generating region 21b of the second solar cell module 21 is located above the frame body 11i of the first solar cell module 11 configured as described above, and the frame body 11i and a portion of the non-power generating region 21b of the second solar cell module 21 are sandwiched with a clamp-type fixture 30, thereby fixing the second solar cell string 22 above the first solar cell string 12. The clamp-type fixture 30 is configured to slide and insert the first solar cell string 12 and the second solar cell string 22, and to sandwich the non-power generating region 21b of the second solar cell module 21 between the frame body 11i of the first solar cell module 11 with a screw-type pressing mechanism 31 provided at the top.

[0070] The clamp-type fixing device 30 may be installed in an appropriate position where it can clamp the frame body 11i and a part of the non-power generating region 21b of the second solar cell module 21, while taking into consideration wind pressure resistance and ease of removal, for example, by attaching it to edges of adjacent first solar cell modules 11 that do not touch each other.

[0071] With this configuration, the second solar cell string 22 can be easily installed above the first solar cell string 12, and the distance between the multiple first solar cell modules 11 that make up the first solar cell string 12 and the multiple second solar cell modules 21 that make up the second solar cell string 22 can be narrowed, allowing sunlight that has passed through the second solar cell modules 21 to be more efficiently irradiated onto the first solar cell modules 11.

[0072] When installing and fixing the second solar cell string 21 above the first solar cell string 12, the terminal box that connects the electrode wires of the second solar cell module 21 to the power cable may be installed taking into consideration the orientation and arrangement of the second solar cell module 21, for example, so as to be off the surface of the first solar cell string 12 so as not to shade the power generation area of ​​the first solar cell string 12.

[0073] As described above, in the installation method for a solar power generation system according to this embodiment and the solar power generation system 1 according to this embodiment, a crystalline silicon solar cell having solar light absorption sensitivity in a predetermined wavelength range is used as the first solar cell module 11, and a transparent perovskite solar cell having solar light absorption sensitivity greater than that of a crystalline silicon solar cell in at least a portion of the above-mentioned predetermined wavelength range is used as the second solar cell module 21.

[0074] As shown in FIG. 9, in the wavelength region of the solar light spectrum, crystalline silicon solar cells and CIS solar cells (compound semiconductor solar cells whose main raw materials are the three elements copper (Cu), indium (In), and selenium (Se)) each have solar light absorption sensitivity in the wavelength region of 400 nm to 1200 nm.

[0075] In contrast, perovskite solar cells have solar light absorption sensitivity in the wavelength range of approximately 350 nm to 800 nm, where the irradiance of sunlight is greater than in other wavelength ranges. Furthermore, in the light absorption wavelength range of perovskite solar cells, the solar light absorption sensitivity of perovskite solar cells is greater than that of crystalline silicon solar cells and CIS solar cells.

[0076] Therefore, second solar cell module 21 using perovskite solar cells can effectively convert sunlight in the wavelength range of approximately 350 nm to 800 nm, which has a relatively high irradiance, into electric power, while first solar cell module 11 using crystalline silicon solar cells can effectively convert into electric power not only sunlight in the wavelength range of 400 nm to 800 nm that has passed through second solar cell module 21 using perovskite solar cells, but also sunlight in the wavelength range of 800 nm to 1200 nm that has passed through second solar cell module 21 using perovskite solar cells but which cannot be effectively converted into electric power by second solar cell module 21 using perovskite solar cells. Therefore, by efficiently converting sunlight in a wide wavelength range into electric power, the solar energy to electric power conversion rate per unit area of ​​solar power generation system 1 can be further improved.

[0077] In the solar power generation system 1 according to this embodiment, a crystalline silicon solar cell is used as the first solar cell module 10, but this is not limited thereto, and other types of non-transparent solar cells such as CIS solar cells may also be used as the first solar cell module 10, or transparent solar cells such as transparent perovskite solar cells may also be used.

[0078] Furthermore, in the solar power generation system 1 according to this embodiment, a transparent perovskite solar cell is used as the second solar cell module 20, but this is not limited thereto, and a transparent solar cell other than a perovskite solar cell may also be used.

[0079] 10 as a modified example, the installation method of the photovoltaic power generation system according to this embodiment can also be configured to install a plurality of second photovoltaic strings 22 corresponding to a plurality of second photovoltaic power generation systems 20 in a stacked manner in multiple tiers above a first photovoltaic string 12 constituting a first photovoltaic power generation system 10. That is, the photovoltaic power generation system 1 according to this embodiment can also be configured to have one first photovoltaic power generation system 10 and a plurality of second photovoltaic power generation systems 20, and to install a plurality of second photovoltaic strings 22 corresponding to a plurality of second photovoltaic power generation systems 20 in a stacked manner in multiple tiers above the first photovoltaic string 12 constituting the first photovoltaic power generation system 10.

[0080] 10 shows a case where two second solar cell strings 22 corresponding to two second solar cell systems 20 are installed in a stacked manner above a first solar cell string 12 constituting a first solar cell power generation system 10. Note that a configuration may also be adopted in which three or more second solar cell strings 22 corresponding to three or more second solar cell systems 20 are installed in a stacked manner above a first solar cell string 12 constituting the first solar cell power generation system 10.

[0081] In this modified example, too, the installation method of the solar power generation system according to this embodiment is such that multiple stages of second solar cell strings 22 are installed above the first solar cell string 12 in a stacked manner so that each first solar cell module 11 generates electricity using sunlight that has passed through each of the multiple stages of transparent second solar cell modules 22.

[0082] In the configuration of this modified example, sunlight is converted into electricity by the upper transmissive second solar cell module 21, sunlight that has passed through the upper second solar cell module 21 is converted into electricity by the lower transmissive second solar cell module 21, and sunlight that has passed through the lower second solar cell module 21 is converted into electricity by the first solar cell module 11. This makes it possible to further increase the solar energy to electricity conversion rate per unit area of ​​the solar power generation system 1.

[0083] In the modified example shown in FIG. 10, a non-transparent perovskite solar cell is used as the first solar cell module 11 of the first solar power generation system 10, but this is not limited thereto, and other types of solar cells such as transparent perovskite solar cells, crystalline silicon solar cells, and CIS solar cells may also be used.

[0084] In addition, in the modified example shown in Figure 10, transparent perovskite solar cells are used as the second solar cell modules 21 of the multi-stage second solar power generation system 20, but transparent solar cells other than perovskite solar cells may also be used.

[0085] In the solar power generation system 1 according to the modification shown in Fig. 10, the arrangement of the second solar cell modules 21 in the multi-stage second solar power generation system 20 can also be the same as the arrangement of the second solar cell modules 21 shown in Fig. 6. In this case, the first solar cell modules 11 made of non-transparent perovskite solar cells do not need to be arranged so that the power generation regions are continuous with each other.

[0086] As shown as another modified example in Figures 11 and 12, the installation method of the solar power generation system according to this embodiment can also be configured such that a third solar power generation system 40 including a third solar cell string 42 having a plurality of third solar cell modules 41 electrically connected in series with each other and a third power conversion device 43 electrically connected to the third solar cell string 42 is installed below the first solar cell string 12 so that each third solar cell module 41 faces away from the first solar cell module 11, i.e., so that sunlight on the third solar cell module 41 faces in the opposite direction to sunlight on the first solar cell module 11. That is, the solar power generation system 1 of this embodiment further includes a third solar power generation system 40 including a third solar cell string 42 having a plurality of third solar cell modules 41 electrically connected in series with each other, and a third power conversion device 43 electrically connected to the third solar cell string 42, and can also be configured such that the third solar cell string 42 is installed below the first solar cell string 12 in a stacked manner so that each third solar cell module 41 faces away from the first solar cell module 11.

[0087] The third solar cell module 41, which is arranged below the first solar cell module 11, is arranged on the opposite side of the first solar cell module 11, i.e., downward, with the substrate 41a facing downward, so that reflected sunlight reflected around the solar power generation system 1 can enter the third solar cell module 41 from below.

[0088] As described above, in another modified example shown in Figures 11 and 12, a transparent second solar cell module 21 is arranged above the first solar cell module 11, and a third solar cell module 41 is arranged below the first solar cell module 11 facing opposite to the first solar cell module 11 (back to back). This allows sunlight to be converted into electricity by the transparent second solar cell module 21, sunlight that has passed through the transparent second solar cell module 21 to be converted into electricity by the first solar cell module 11, and sunlight reflected around the solar power generation system 1 to be converted into electricity by the third solar cell module 41 facing opposite to the first solar cell module 11, thereby further increasing the conversion rate of solar energy to electricity per unit area of ​​the solar power generation system 1.

[0089] In other modified examples shown in Figures 11 and 12, a non-transparent perovskite solar cell is used as the first solar cell module 11 of the first solar power generation system 10, but this is not limited to this, and other types of solar cells such as transparent perovskite solar cells, crystalline silicon solar cells, and CIS solar cells may also be used.

[0090] In addition, in other modified examples shown in Figures 11 and 12, a transparent perovskite solar cell is used as the second solar cell module 21 of the second solar power generation system 20, but a transparent solar cell other than a perovskite solar cell may also be used.

[0091] Furthermore, in other modified examples shown in Figures 11 and 12, a non-transparent perovskite solar cell is used as the fourth solar cell module 41 of the third solar power generation system 40, but this is not limited to this, and other types of solar cells such as transparent perovskite solar cells, crystalline silicon solar cells, and CIS solar cells may also be used.

[0092] Furthermore, in other modified examples shown in Figures 11 and 12, similar to the modified example shown in Figure 10, a configuration can be adopted in which multiple second solar cell strings 22 corresponding to multiple second solar cell systems 20 are installed in a stacked manner above the first solar cell string 12 that constitutes the first solar cell power generation system 10.

[0093] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0094] 1. Solar power generation system 10. The First Solar Power Generation System 11 First solar cell module 11a Solar cell 11b Back seat 11c metal frame 11d Cell String 11e Bypass Diode 11f cluster 11g support plate 11h Back sheet 11i frame 12 First solar cell string 13 First power conversion device 20 Second Solar Power Generation System 21 Second solar cell module 21a Power Generation Area 21b Non-power generation area 21c 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 conversion device 30 Clamp-type fixing device 31 Screw-type pressing mechanism 40 The Third Solar Power Generation System 41 Third solar cell module 41a substrate 42 Third solar cell string 43 Third power conversion device

Claims

1. a first solar power generation system including a first solar cell string including a plurality of first solar cell modules electrically connected in series with each other, and a first power conversion device electrically connected to the first solar cell string; a second solar power generation system including a second solar cell string including a plurality of second transparent solar cell modules electrically connected in series with each other, and a second power conversion device electrically connected to the second solar cell string; A solar power generation system having a second solar cell string being installed above the first solar cell string so that each of the first solar cell modules generates electricity using sunlight that has passed through the second solar cell module;

2. The first solar cell module has a solar light absorption sensitivity in a predetermined wavelength range, The method for installing a photovoltaic power generation system according to claim 1 , wherein the second solar cell module has a higher solar light absorption sensitivity than the first solar cell module in at least a part of the wavelength range.

3. a crystalline silicon solar cell is used as the first solar cell module; The method for installing a solar power generation system according to claim 2 , wherein a transparent perovskite solar cell is used as the second solar cell module.

4. The second solar cell module is a rectangular solar cell module having a rectangular power generating region and a non-power generating region provided around the entire periphery of the power generating region, 4. The installation method for a solar power generation system according to claim 3, wherein the plurality of second solar cell modules are arranged so that the power generation areas of adjacent second solar cell modules are adjacent to each other when viewed from a direction perpendicular to the second solar cell modules.

5. 5. The method for installing a photovoltaic power generation system according to claim 1, wherein a third photovoltaic power generation system includes a third photovoltaic string including a plurality of third photovoltaic modules electrically connected in series with each other, and a third power conversion device electrically connected to the third photovoltaic string, and the third photovoltaic string is installed below the first photovoltaic string so that each of the third photovoltaic modules faces away from the first photovoltaic modules.

6. a first solar power generation system including a first solar cell string including a plurality of first solar cell modules electrically connected in series with each other, and a first power conversion device electrically connected to the first solar cell string; a second solar power generation system including a second solar cell string including a plurality of second transparent solar cell modules electrically connected in series with each other, and a second power conversion device electrically connected to the second solar cell string; A solar power generation system having: A solar power generation system characterized in that the second solar cell string is installed above the first solar cell string so that each of the first solar cell modules generates electricity using sunlight that has passed through the second solar cell module.

7. the first solar cell module has solar light absorption sensitivity in a predetermined wavelength range, The solar power generation system according to claim 6 , wherein the second solar cell module has a higher solar light absorption sensitivity than the first solar cell module in at least a part of the wavelength range.

8. the first solar cell module is a crystalline silicon solar cell, The solar power generation system according to claim 7 , wherein the second solar cell module is a transparent perovskite solar cell.

9. the second solar cell module has a rectangular shape including a rectangular power generating region and a non-power generating region provided around the entire periphery outside the power generating region, 9. The solar power generation system according to claim 8, wherein the plurality of second solar cell modules are arranged such that the power generation areas of adjacent second solar cell modules are adjacent to each other when viewed from a direction perpendicular to the second solar cell modules.

10. a third solar power generation system including a third solar cell string including a plurality of third solar cell modules electrically connected in series with each other, and a third power conversion device electrically connected to the third solar cell string; The solar power generation system according to any one of claims 6 to 9, wherein the third solar cell string is installed below the first solar cell string so that each of the third solar cell modules faces opposite to the first solar cell module.

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