Photovoltaic power generation system

Abstract

To provide a photovoltaic power generation system including a tandem type solar cell module in which movement of chloride ions derived from material of a perovskite layer is suppressed.SOLUTION: A photovoltaic power generation system 1 comprises a solar cell string 10 in which M four terminal type tandem type solar cell modules 20, each of which includes a crystalline silicon system solar cell sub-module 22 and a perovskite system solar cell sub-module 24, are connected. The M sub-modules 22 constitute a crystalline silicon system solar cell string 12; the M sub-modules 24 constitute a perovskite system solar cell string 14. When output voltage of the string 14 is larger than output voltage of the string 12, negative potential terminals of these strings are connected to the same reference potential; when the output voltage of the string 14 is smaller than the output voltage of the string 12, positive potential terminals of these strings are connected to the same reference potential.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a photovoltaic power generation system. [Background technology]

[0002] A solar power generation system includes a solar cell string in which multiple solar cell modules are connected in series or in parallel, and a power conditioner (also called a power conditioning system: PCS) that converts DC power from the solar cell string into desired AC power or DC power.

[0003] In recent years, tandem (multi-junction) solar cell modules have been known in which photoelectric conversion layers with different bandgaps are stacked together, with the aim of effectively utilizing light in a wide wavelength range to increase the conversion efficiency of the solar cell module. Examples of photoelectric conversion layers include crystalline silicon substrates, inorganic thin films such as amorphous silicon thin films, organic thin films, and organic-inorganic hybrid thin films (e.g., perovskite thin films). For example, Patent Documents 1 to 3 disclose tandem solar cell modules in which two types of solar cell submodules, each containing a different photoelectric conversion layer, such as a crystalline silicon solar cell submodule and a perovskite solar cell submodule, are stacked together. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 102128 [Patent Document 2] International Publication No. 2022 / 101969 [Patent Document 3] International Publication No. 2022 / 080196 Summary of the Invention [Problem to be solved by the invention]

[0005] Perovskite solar cell submodules may contain chlorine Cl as a material of the perovskite layer. In this case, if the potential of the crystalline silicon solar cell submodule is higher than the potential of the perovskite solar cell submodule in a tandem solar cell module, chlorine ions Cl derived from the material of the perovskite layer may be released. - is transferred from the perovskite-based solar cell sub-module to the crystalline silicon-based solar cell sub-module.

[0006] This may lead to the following problems: Corrosion of electrodes and interconnections of crystalline silicon solar cells in crystalline silicon solar cell submodules - Bubbles generated by gasification of chlorine Cl Sodium ions (Na) derived from glass in the backside protective material + The reaction between chlorine and sodium chloride (Cl) causes the precipitation of sodium chloride (NaCl), which further accelerates the corrosion described above.

[0007] The present invention is directed to a tandem solar cell module that utilizes chloride ions Cl derived from the perovskite layer material. - The object of the present invention is to provide a solar power generation system that suppresses the movement of [Means for solving the problem]

[0008] The solar cell module according to the present invention includes a solar cell string (M is an integer of 1 or greater) in which M four-terminal tandem solar cell modules, each including a crystalline silicon solar cell submodule and a perovskite solar cell submodule, are electrically connected. In the solar cell string, the M crystalline silicon solar cell submodules in the M tandem solar cell modules are connected in series or parallel to form a crystalline silicon solar cell string, and the M perovskite solar cell submodules in the M tandem solar cell modules are connected in series or parallel to form a perovskite solar cell string. When the output voltage of the perovskite solar cell string is higher than the output voltage of the crystalline silicon solar cell string, the negative potential terminal of the perovskite solar cell string and the negative potential terminal of the crystalline silicon solar cell string are connected to the same reference potential. When the output voltage of the perovskite solar cell string is lower than the output voltage of the crystalline silicon solar cell string, the positive potential terminal of the perovskite solar cell string and the positive potential terminal of the crystalline silicon solar cell string are connected to the same reference potential. [Effects of the Invention]

[0009] According to the present invention, in a tandem solar cell module, chloride ions Cl derived from the material of the perovskite layer are - The movement of the particles can be suppressed. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing the configuration of a solar power generation system according to an embodiment of the present invention. [Figure 2] 1 is a schematic cross-sectional view of a solar cell module according to an embodiment of the present invention. [Figure 3] FIG. 3 is a schematic cross-sectional view of a perovskite solar cell sub-module in the solar cell module shown in FIG. 2. [Figure 4] FIG. 3 is a schematic cross-sectional view of the solar cell module shown in FIG. 2. [Figure 5] FIG. 2 is a schematic diagram of a solar cell string in the solar power generation system shown in FIG. [Figure 6] FIG. 2 is a schematic diagram of a solar cell string in the solar power generation system shown in FIG. [Figure 7] FIG. 10 is a schematic diagram showing the configuration of a solar power generation system according to a modified example of the present embodiment. [Figure 8] FIG. 8 is a schematic diagram of a solar cell string in the solar power generation system shown in FIG. [Figure 9] FIG. 8 is a schematic diagram of a solar cell string in the solar power generation system shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] An example of an embodiment of the present invention will be described below with reference to the accompanying drawings. The same or equivalent parts in each drawing are designated by the same reference numerals. For convenience, hatching and reference numerals may be omitted. In such cases, reference should be made to other drawings.

[0012] (Solar power generation system) 1 is a schematic diagram showing the configuration of a solar power generation system according to this embodiment. As shown in FIG. 1, the solar power generation system 1 includes a solar cell string 10 and a power conditioning system (PCS) 30.

[0013] The solar cell string 10 includes M solar cell modules 20 (M is an integer of 1 or more) electrically connected between two positive potential terminals P and two negative potential terminals N. In the following, when referring to each of the M solar cell modules 20, it may be referred to as the m-th solar cell module from the negative potential terminal N side of the solar cell string 10 (m is an integer of 1 or more and M or less).

[0014] The solar cell module 20 is a tandem solar cell module in which a bottom-side solar cell submodule 22 and a top-side solar cell submodule 24 are stacked, and is a four-terminal solar cell module. In the solar cell module 20, the bottom-side solar cell submodule 22 and the top-side solar cell submodule 24 are electrically insulated from each other.

[0015] In the solar cell string 10, M bottom solar cell submodules 22 in M ​​solar cell modules 20 form a bottom solar cell string 12 connected in series between one positive potential terminal P and one negative potential terminal N, and M top solar cell submodules 24 in M ​​solar cell modules 20 form a top solar cell string 14 connected in series between the other positive potential terminal P and the other negative potential terminal N.

[0016] The bottom solar cell submodule 22 includes a plurality of solar cells (or solar cell panels) connected in series, and the top solar cell submodule 24 includes a plurality of solar cells (or solar cell panels) connected in series.

[0017] The power conditioner 30 converts DC power from the bottom-side solar cell string 12 in the solar cell string 10 into desired AC power or DC power, converts DC power from the top-side solar cell string 14 in the solar cell string 10 into desired AC power or DC power, and combines these converted powers. The power conditioner 30 may have a maximum power point tracking (MPPT) function that tracks the optimal operating point (maximum power point) of the output power of the bottom-side solar cell string 12 in the solar cell string 10, or may have a maximum power point tracking (MPPT) function that tracks the optimal operating point (maximum power point) of the output power of the top-side solar cell string 14 in the solar cell string 10.

[0018] (solar cell module) Fig. 2 is a schematic cross-sectional view of a solar cell module according to this embodiment. As described above, the solar cell module 20 shown in Fig. 2 is a tandem solar cell module in which a bottom-side solar cell submodule 22 and a top-side solar cell submodule 24 are stacked, and is a four-terminal solar cell module. In the solar cell module 20, an insulating member such as a sealing material 5 described below is interposed between the bottom-side solar cell submodule 22 and the top-side solar cell submodule 24.

[0019] As described above, the bottom solar cell submodule 22 includes a plurality of solar cell cells 22S connected in series, and the top solar cell submodule 24 includes a plurality of solar cell cells 24S connected in series.

[0020] The solar cell submodules 22 and 24 are sandwiched between a light-receiving-side protection member 3 and a back-side protection member 4. A liquid or solid sealing material 5 is filled between the light-receiving-side protection member 3 and the back-side protection member 4, thereby sealing the solar cell submodules 22 and 24.

[0021] The sealing material 5 seals and protects the solar cell submodules 22, 24, and is interposed between the light-receiving surface of the top-side solar cell submodule 24 and the light-receiving-side protection member 3, and between the back surface of the bottom-side solar cell submodule 22 and the back-side protection member 4. The shape of the sealing material 5 is not particularly limited, and may be, for example, a sheet. This is because a sheet shape makes it easy to cover the front and back surfaces of the planar solar cell submodules 22, 24.

[0022] The material for the encapsulant 5 is not particularly limited, but preferably has the property of transmitting light (translucency). Furthermore, the material for the encapsulant 5 preferably has adhesive properties that allow the top-side solar cell submodule 24 to adhere to the light-receiving-side protection member 3, and that allow the bottom-side solar cell submodule 22 to adhere to the back-side protection member 4. Examples of such materials include translucent resins such as ethylene / vinyl acetate copolymer (EVA), ethylene / α-olefin copolymer, ethylene / vinyl acetate / triallyl isocyanurate (EVAT), polyvinyl butyrate (PVB), acrylic resin, urethane resin, and silicone resin.

[0023] The light-receiving-side protection member 3 covers the surfaces (light-receiving surfaces) of the solar cell submodules 22, 24 via the sealing material 5, thereby protecting the solar cell submodules 22, 24. The shape of the light-receiving-side protection member 3 is not particularly limited, but a plate or sheet shape is preferable in order to indirectly cover the planar light-receiving surface.

[0024] The material for the light-receiving-side protective member 3 is not particularly limited, but, like the encapsulant 5, a material that is translucent and resistant to ultraviolet light is preferred. Examples include glass or transparent resins such as acrylic resin or polycarbonate resin. The surface of the light-receiving-side protective member 3 may be textured or coated with an anti-reflective coating layer. This configuration makes it difficult for the light-receiving-side protective member 3 to reflect the received light, allowing more light to be guided to the solar cell submodules 22 and 24. When the light-receiving-side protective member 3 is made of resin, a barrier film that prevents water vapor from passing through may be provided on the front or rear surface of the light-receiving-side protective member 3. This protects the solar cell module 20 from water vapor.

[0025] The back-side protection member 4 covers the back surfaces of the solar cell submodules 22, 24 via the sealing material 5, thereby protecting the solar cell submodules 22, 24. The shape of the back-side protection member 4 is not particularly limited, but similar to the light-receiving-side protection member 3, a plate or sheet shape is preferable in order to indirectly cover the planar back surface.

[0026] The material for the backside protection member 4 is not particularly limited, but is preferably a material that prevents the intrusion of water (highly water-resistant). Examples include resin films such as polyethylene terephthalate (PET), polyethylene (PE), olefin-based resins, fluorine-containing resins, and silicone-containing resins, or laminates of a translucent plate-shaped resin material such as glass, polycarbonate, or acrylic with a metal foil such as aluminum foil. When the backside protection member 4 is made of resin, a barrier film that prevents the passage of water vapor may be provided on the front or back surface of the backside protection member 4. This can protect the solar cell submodules 22, 24 from water vapor.

[0027] <Bottom solar cell submodule: Crystalline silicon solar cell submodule> The bottom-side solar cell submodule 22 is a crystalline silicon solar cell submodule including a plurality of crystalline silicon solar cell cells 22S (hereinafter, the bottom-side solar cell submodule is also referred to as a crystalline silicon solar cell submodule, and the bottom-side solar cell string is also referred to as a crystalline silicon solar cell string.) For example, the plurality of crystalline silicon solar cell cells 22S are connected in series, and the crystalline silicon solar cell submodule 22 constitutes a two-terminal module.

[0028] <<Crystalline silicon solar cells>> The crystalline silicon solar cell 22S includes a semiconductor substrate as a photoelectric conversion layer. The semiconductor substrate absorbs light and generates photocarriers. The semiconductor substrate is a crystalline silicon substrate such as single crystal silicon or polycrystalline silicon.

[0029] The semiconductor substrate may have a pyramidal micro-relief structure called a texture structure on the light-receiving surface side, which reduces reflection of incident light on the light-receiving surface and improves the light trapping effect in the semiconductor substrate.

[0030] The semiconductor substrate may also have a pyramidal micro-relief structure, known as a texture structure, on the back surface, which increases the recovery efficiency of light that passes through the semiconductor substrate without being absorbed.

[0031] Examples of crystalline silicon solar cell 22S include a diffusion type cell in which a second conductivity type diffusion layer is provided on the light receiving surface side of a first conductivity type single crystalline silicon substrate, and a heterojunction cell in which a silicon-based thin film is provided on both sides of a first conductivity type single crystalline silicon substrate.

[0032] In the case of a heterojunction cell having silicon-based thin films on the front and back of a single-crystal silicon substrate, the crystalline silicon-based solar cell 22S has a conductive silicon-based thin film formed on the light-receiving surface side of the photoelectric conversion layer and a conductive silicon-based thin film formed on the back side of the photoelectric conversion layer.

[0033] The single crystal silicon substrate can be either p-type or n-type. Since electrons have a higher mobility than holes, the use of an n-type single crystal silicon substrate provides particularly excellent conversion characteristics. The conductive silicon thin film can be either a p-type silicon thin film or an n-type silicon thin film.

[0034] It is preferable that an intrinsic silicon-based thin film is provided between the single-crystal silicon substrate as the photoelectric conversion layer and the conductive silicon-based thin film. By providing an intrinsic silicon-based thin film on the surface of the single-crystal silicon substrate, surface passivation can be effectively performed while suppressing the diffusion of impurities into the single-crystal silicon substrate. By providing an intrinsic amorphous silicon thin film as the intrinsic silicon-based thin film on the surface of the single-crystal silicon substrate, a high passivation effect can be obtained for the surface of the single-crystal silicon substrate.

[0035] The crystalline silicon solar cell 22S may be a double-sided electrode type (also called a double-sided junction type) cell or a back electrode type (also called a back junction type or back contact type) cell. Note that a back electrode type cell can improve the output of the solar cell module and the design of the solar cell module compared to a double-sided electrode type cell.

[0036] The crystalline silicon solar cell 22S may be a large semiconductor substrate (wafer) of a specified size (for example, a 6-inch semi-square shape), or may be a half-cut cell obtained by cutting a large semiconductor substrate (wafer) in two.

[0037] <Top solar cell submodule: Perovskite solar cell submodule> The top-side solar cell submodule 24 is a perovskite-based solar cell submodule including a plurality of perovskite-based solar cell cells 24S (hereinafter, the top-side solar cell submodule will also be referred to as a perovskite-based solar cell submodule, and the top-side solar cell string will also be referred to as a perovskite-based solar cell string).

[0038] <<Perovskite solar cells>> The perovskite solar cell 24S includes a thin-film semiconductor layer as a photoelectric conversion layer. The semiconductor layer absorbs light and generates photocarriers. The semiconductor layer has a band gap different from that of the semiconductor substrate of the crystalline silicon solar cell described above. Therefore, the semiconductor substrate and semiconductor layer have spectral sensitivity characteristics in different wavelength ranges. Therefore, in a tandem solar cell module in which the crystalline silicon solar cell submodule 22 and the perovskite solar cell submodule 24 described above are stacked, light with a wider wavelength range can be contributed to photoelectric conversion.

[0039] Specifically, examples of thin films constituting the semiconductor layer include organic semiconductor thin films, more specifically organic-inorganic hybrid semiconductor thin films, such as perovskite thin films containing a photosensitive material with a perovskite crystal structure.

[0040] The compound constituting the perovskite crystal material is not particularly limited, but for example, 1 NH3M 1 X3 or HC(NH2)2M 1 X3, where R 1 is an alkyl group, preferably an alkyl group having 1 to 5 carbon atoms, and particularly preferably a methyl group. 1 is a divalent metal ion, preferably Pb or Sn. X is a halogen, such as F, Cl, Br, or I. All three Xs may be the same halogen element, or multiple halogens may be mixed.

[0041] A preferred example of a compound constituting a perovskite-type crystal material is a compound having the formula CH3NH3Pb(I 1-x Br x )3 (where 0≦x≦1). The spectral sensitivity characteristics of perovskite materials can be changed by changing the type and ratio of halogens. Perovskite semiconductor thin films can be formed by various dry processes or solution film formation such as spin coating.

[0042] Figure 3 is a schematic cross-sectional view of the perovskite solar cell submodule 24 in the solar cell module 20 shown in Figure 2. As shown in Figure 3, the perovskite solar cell submodule 24 is divided in the X direction (integration direction: first direction) on a single base material 30b, extends in the Y direction (second direction) intersecting the X direction, and is composed of a plurality of perovskite solar cell cells 24S connected in series and integrated. This shortens the conductive distance in the X direction and reduces the amount of current per cell 24S, resulting in a reduction in resistance loss due to the electrodes 34, 35, particularly the electrodes 34, 35 made of transparent electrodes (ITO).

[0043] The solar cell 24S is formed on a film-like or plate-like substrate 30b. Materials for the substrate 30b include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), glass, and the like.

[0044] The solar cell 24S has a perovskite layer 31 as a photoelectric conversion layer, and charge transport layers 32 and 33. One of the charge transport layers 32 and 33 is a hole transport layer, and the other is an electron transport layer.

[0045] Examples of materials for the hole transport layer include polythiophene derivatives such as poly-3-hexylthiophene (P3HT) and poly(3,4-ethylenedioxythiophene) (PEDOT), fluorene derivatives such as 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (Spiro-OMeTAD), carbazole derivatives such as polyvinylcarbazole, triphenylamine derivatives, diphenylamine derivatives, polysilane derivatives, and polyaniline derivatives.

[0046] Examples of materials for the electron transport layer include metal oxides such as titanium oxide, zinc oxide, niobium oxide, zirconium oxide, and aluminum oxide.

[0047] An electrode 34 for extracting photogenerated carriers is formed on the charge transport layer 32 side of solar cell 24S. An electrode 35 for extracting photogenerated carriers is formed on the charge transport layer 33 side of solar cell 24S.

[0048] The electrode 34 may include a transparent electrode and a metal electrode, or may include only a transparent electrode, or may include only a metal electrode. Similarly, the electrode 35 may include a transparent electrode and a metal electrode, or may include only a transparent electrode, or may include only a metal electrode. Metal oxides such as ITO, zinc oxide, and tin oxide are preferably used as materials for the transparent electrode. Silver, copper, aluminum, and the like are preferably used as materials for the metal electrode.

[0049] (Operation method of solar cell string 10) As described above, the perovskite solar cell submodule 24 may contain chlorine Cl as a material of the perovskite layer 31. In this case, as shown in FIG. 4 , in the tandem solar cell module 20, if the potential of the crystalline silicon solar cell submodule 22 is higher than the potential of the perovskite solar cell submodule 24, chlorine ions Cl derived from the material of the perovskite layer 31 will be released. - moves from the perovskite-based solar cell submodule 24 to the crystalline silicon-based solar cell submodule 22.

[0050] This may lead to the following problems: Corrosion of the electrodes and interconnections of the crystalline silicon solar cell 22S in the crystalline silicon solar cell submodule 22 - Bubbles generated by gasification of chlorine Cl Sodium ions (Na) derived from the glass of the rear protective material 4, etc. + The reaction between chlorine and sodium chloride (Cl) causes the precipitation of sodium chloride (NaCl), which further accelerates the corrosion described above.

[0051] In this regard, according to the solar power generation system 1 of this embodiment, when the output voltage of the perovskite solar cell string 14 is greater than the output voltage of the crystalline silicon solar cell string 12, the negative potential terminal N of the perovskite solar cell string 14 and the negative potential terminal N of the crystalline silicon solar cell string 12 are connected to the same reference potential. On the other hand, when the output voltage of the perovskite solar cell string 14 is smaller than the output voltage of the crystalline silicon solar cell string 12, the positive potential terminal P of the perovskite solar cell string 14 and the positive potential terminal P of the crystalline silicon solar cell string 12 are connected to the same reference potential.

[0052] For example, as shown in Figure 5, when the output voltage of the perovskite solar cell string 14 is greater than the output voltage of the crystalline silicon solar cell string 12, that is, when the output voltage of the perovskite solar cell submodule 24 is greater than the output voltage of the crystalline silicon solar cell submodule 22, the negative potential terminal N of the perovskite solar cell string 14 and the negative potential terminal N of the crystalline silicon solar cell string 12 are grounded.

[0053] As a result, in the first solar cell module 20, the potential of the positive potential terminal + of the perovskite solar cell submodule 24 is higher than the potential of the positive potential terminal + of the crystalline silicon solar cell submodule 22. Furthermore, in the m-th solar cell modules 20 other than the first, the potential of the negative potential terminal − of the perovskite solar cell submodule 24 is higher than the potential of the negative potential terminal − of the crystalline silicon solar cell submodule 22, and the potential of the positive potential terminal + of the perovskite solar cell submodule 24 is higher than the potential of the positive potential terminal + of the crystalline silicon solar cell submodule 22. That is, at least at the positive potential terminal + of the M solar cell modules 20, the potential of the perovskite solar cell submodule 24 is higher than the potential of the crystalline silicon solar cell submodule 22. In this way, in each of the M tandem solar cell modules 20, the potential of the perovskite solar cell submodule 24 is configured to be higher than the potential of the crystalline silicon solar cell submodule 22.

[0054] On the other hand, for example, as shown in Figure 6, when the output voltage of the perovskite solar cell string 14 is smaller than the output voltage of the crystalline silicon solar cell string 12, that is, when the output voltage of the perovskite solar cell submodule 24 is smaller than the output voltage of the crystalline silicon solar cell submodule 22, the positive potential terminal P of the perovskite solar cell string 14 and the positive potential terminal P of the crystalline silicon solar cell string 12 are grounded.

[0055] As a result, in the fifth solar cell module 20, the potential of the negative potential terminal − of the perovskite solar cell submodule 24 is higher than the potential of the negative potential terminal − of the crystalline silicon solar cell submodule 22. Furthermore, in the m-th solar cell modules 20 other than the fifth, the potential of the positive potential terminal + of the perovskite solar cell submodule 24 is higher than the potential of the positive potential terminal + of the crystalline silicon solar cell submodule 22, and the potential of the negative potential terminal − of the perovskite solar cell submodule 24 is higher than the potential of the negative potential terminal − of the crystalline silicon solar cell submodule 22. That is, at least at the negative potential terminal − of the M solar cell modules 20, the potential of the perovskite solar cell submodule 24 is higher than the potential of the crystalline silicon solar cell submodule 22. In this way, in each of the M tandem solar cell modules 20, the potential of the perovskite solar cell submodule 24 is configured to be higher than the potential of the crystalline silicon solar cell submodule 22.

[0056] This allows the chloride ions (Cl ) from the perovskite layer material to be released. - ) can be prevented (suppressed) from migrating from the perovskite-based solar cell submodule 24 to the crystalline silicon-based solar cell submodule 22, and the above-mentioned problems can be prevented (suppressed).

[0057] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and various modifications and variations are possible. For example, the above-described embodiments illustrate a configuration in which the negative potential terminal N of the perovskite solar cell string 14 and the negative potential terminal N of the crystalline silicon solar cell string 12 are grounded when the output voltage of the perovskite solar cell string 14 is higher than the output voltage of the crystalline silicon solar cell string 12. However, the present invention is not limited to this configuration, and the negative potential terminal N of the perovskite solar cell string 14 and the negative potential terminal N of the crystalline silicon solar cell string 12 may be set to the same reference potential. Even in this configuration, the potential of the perovskite solar cell sub-module 24 in each of the M tandem solar cell modules 20 can be configured to be higher than the potential of the crystalline silicon solar cell sub-module 22.

[0058] Furthermore, the negative potential terminals N of the crystalline silicon solar cell strings 12 may be grounded or set to the same reference potential via a resistor. According to this embodiment, in each of the M tandem solar cell modules 20, the potential of the perovskite solar cell sub-modules 24 can be configured to be even higher than the potential of the crystalline silicon solar cell sub-modules 22.

[0059] Similarly, in the above-described embodiment, when the output voltage of the perovskite solar cell string 14 is smaller than the output voltage of the crystalline silicon solar cell string 12, the positive potential terminal P of the perovskite solar cell string 14 and the positive potential terminal P of the crystalline silicon solar cell string 12 are grounded. However, the present invention is not limited to this, and the positive potential terminal P of the perovskite solar cell string 14 and the positive potential terminal P of the crystalline silicon solar cell string 12 may be set to the same reference potential. Even in this embodiment, in each of the M tandem solar cell modules 20, the potential of the perovskite solar cell sub-module 24 can be configured to be higher than the potential of the crystalline silicon solar cell sub-module 22.

[0060] Furthermore, the positive potential terminals P of the perovskite solar cell strings 14 may be grounded or set to the same reference potential via a resistor. According to this embodiment, in each of the M tandem solar cell modules 20, the potential of the perovskite solar cell sub-modules 24 can be configured to be even higher than the potential of the crystalline silicon solar cell sub-modules 22.

[0061] Furthermore, in the above-described embodiment, an example has been given of a configuration in which M perovskite solar cell sub-modules 24 are connected in series in M ​​tandem solar cell modules 20. However, the features of the present invention are not limited to this, and are also applicable to a configuration in which M perovskite solar cell sub-modules 24 are connected in parallel in M ​​tandem solar cell modules 20, as shown in Fig. 7, for example.

[0062] Even in this configuration, when the output voltage of the perovskite solar cell string 14 is greater than the output voltage of the crystalline silicon solar cell string 12, the negative potential terminal N of the perovskite solar cell string 14 and the negative potential terminal N of the crystalline silicon solar cell string 12 are connected to the same reference potential. On the other hand, when the output voltage of the perovskite solar cell string 14 is smaller than the output voltage of the crystalline silicon solar cell string 12, the positive potential terminal P of the perovskite solar cell string 14 and the positive potential terminal P of the crystalline silicon solar cell string 12 are connected to the same reference potential.

[0063] For example, as shown in Figure 8, when the output voltage of the perovskite solar cell string 14 is greater than the output voltage of the crystalline silicon solar cell string 12, that is, when the output voltage of each of the perovskite solar cell submodules 24 is greater than the output voltage of the crystalline silicon solar cell string 12, the negative potential terminal N of the perovskite solar cell string 14 and the negative potential terminal N of the crystalline silicon solar cell string 12 are grounded.

[0064] On the other hand, for example, as shown in Figure 9, when the output voltage of the perovskite solar cell string 14 is smaller than the output voltage of the crystalline silicon solar cell string 12, that is, when the output voltage of each of the perovskite solar cell submodules 24 is smaller than the output voltage of the crystalline silicon solar cell string 12, the positive potential terminal P of the perovskite solar cell string 14 and the positive potential terminal P of the crystalline silicon solar cell string 12 are grounded.

[0065] This allows a relatively large number of states in which the potential of the perovskite solar cell string 14 is higher than the potential of the crystalline silicon solar cell string 12. Therefore, the chlorine ions (Cl - ) can be prevented from migrating from the perovskite-based solar cell submodule 24 to the crystalline silicon-based solar cell submodule 22, thereby preventing the above-mentioned problems.

[0066] Even in this configuration, if the output voltage of the perovskite solar cell string 14 is higher than the output voltage of the crystalline silicon solar cell string 12, the negative potential terminal N of the perovskite solar cell string 14 and the negative potential terminal N of the crystalline silicon solar cell string 12 may be set to the same reference potential. This makes it possible to relatively frequently increase the number of states in which the potential of the perovskite solar cell string 14 is higher than the potential of the crystalline silicon solar cell string 12.

[0067] Furthermore, the negative potential terminal N of the crystalline silicon solar cell string 12 may be grounded or set to the same reference potential via a resistor, thereby increasing the number of states in which the potential of the perovskite solar cell string 14 is higher than the potential of the crystalline silicon solar cell string 12.

[0068] Similarly, when the output voltage of the perovskite solar cell string 14 is smaller than the output voltage of the crystalline silicon solar cell string 12, the positive potential terminal P of the perovskite solar cell string 14 and the positive potential terminal P of the crystalline silicon solar cell string 12 may be set to the same reference potential. This makes it possible to relatively frequently increase the number of states in which the potential of the perovskite solar cell string 14 is higher than the potential of the crystalline silicon solar cell string 12.

[0069] Furthermore, the positive potential terminal P of the perovskite solar cell string 14 may be grounded or set to the same reference potential via a resistor. This increases the number of situations in which the potential of the perovskite solar cell string 14 is higher than the potential of the crystalline silicon solar cell string 12.

[0070] Furthermore, in the above-described embodiment, an example has been given in which M crystalline silicon solar cell submodules 22 in M ​​tandem solar cell modules 20 are connected in series. However, the features of the present invention are not limited to this, and the present invention can also be applied to an example in which M crystalline silicon solar cell submodules 22 in M ​​tandem solar cell modules 20 are connected in parallel. [Explanation of symbols]

[0071] 1. Solar power generation system 3. Light receiving side protection member 4 Back protection material 5. Encapsulating material 10 solar cell strings 12 Bottom solar cell string (crystalline silicon solar cell string) 14 Top-side solar cell string (perovskite solar cell string) 20 Solar cell modules 22 Bottom side solar cell submodule (crystalline silicon solar cell submodule) 22S crystalline silicon solar cell 24 Top-side solar cell submodule (perovskite solar cell submodule) 24S Perovskite solar cell 30 Power Conditioner 30b Base material 31 Photoelectric conversion layer 32,33 Charge transport layer 34,35 electrode

Claims

1. a solar cell string in which M four-terminal tandem solar cell modules, each including a crystalline silicon solar cell sub-module and a perovskite solar cell sub-module, are electrically connected, where M is an integer of 1 or greater; In the solar cell string, the M crystalline silicon solar cell sub-modules in the M tandem solar cell modules constitute a crystalline silicon solar cell string connected in series or in parallel, the M perovskite solar cell sub-modules in the M tandem solar cell modules constitute a perovskite solar cell string connected in series or in parallel; When the output voltage of the perovskite solar cell string is greater than the output voltage of the crystalline silicon solar cell string, a negative potential terminal of the perovskite solar cell string and a negative potential terminal of the crystalline silicon solar cell string are connected to the same reference potential; when the output voltage of the perovskite solar cell string is smaller than the output voltage of the crystalline silicon solar cell string, the positive potential terminal of the perovskite solar cell string and the positive potential terminal of the crystalline silicon solar cell string are connected to the same reference potential; Solar power generation system.

2. when the output voltage of the perovskite solar cell string is greater than the output voltage of the crystalline silicon solar cell string, a negative potential terminal of the perovskite solar cell string and a negative potential terminal of the crystalline silicon solar cell string are grounded; when the output voltage of the perovskite solar cell string is smaller than the output voltage of the crystalline silicon solar cell string, the positive potential terminal of the perovskite solar cell string and the positive potential terminal of the crystalline silicon solar cell string are grounded; The solar power generation system according to claim 1 .

3. the M crystalline silicon solar cell sub-modules in the M tandem solar cell modules constitute a crystalline silicon solar cell string connected in series, the M perovskite solar cell sub-modules in the M tandem solar cell modules constitute a perovskite solar cell string connected in series; In each of the M tandem solar cell modules, the potential of the perovskite solar cell sub-module is configured to be higher than the potential of the crystalline silicon solar cell sub-module. The solar power generation system according to claim 1 or 2.

4. the M crystalline silicon solar cell sub-modules in the M tandem solar cell modules constitute a crystalline silicon solar cell string connected in series, the M perovskite solar cell sub-modules in the M tandem solar cell modules constitute a perovskite solar cell string connected in parallel, When the output voltage of each of the perovskite solar cell sub-modules is greater than the output voltage of the crystalline silicon solar cell string, the negative potential terminal of each of the perovskite solar cell sub-modules and the negative potential terminal of the crystalline silicon solar cell string are connected to the same reference potential; when the output voltage of each of the perovskite solar cell sub-modules is smaller than the output voltage of the crystalline silicon solar cell string, the positive potential terminal of each of the perovskite solar cell sub-modules and the positive potential terminal of the crystalline silicon solar cell string are connected to the same reference potential; The solar power generation system according to claim 1 .

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