JP2018157175A - Solar cell module and solar power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell module and a solar power generation system capable of improving conversion efficiency.SOLUTION: A solar cell module includes: a first solar cell panel 10 which has plural first sub-modules including plural first solar cells; and a second solar cell panel 20 which has plural second sub-modules including plural second solar cells, and is laminated on the first solar cell panel. The first solar cell panel is positioned at a light incident side, and the first solar cell panel and the second solar cell panel are connected electrically in parallel to each other. The plural first solar cells included in the plural first sub-modules are electrically connected in series to one another, and the plural first sub-modules are electrically connected in parallel to one another. The plural second solar cells included in the plural second sub-modules are electrically connected in series to one another, and the plural second sub-modules are electrically connected in parallel to one another.SELECTED DRAWING: Figure 1

Description

  Embodiments relate to a solar cell module and a photovoltaic power generation system.

  There is a multi-junction (tandem) solar cell as a highly efficient solar cell. Since an efficient cell can be used for each wavelength band, higher efficiency than a single junction is expected. Chalcopyrite solar cells such as CIGS (a compound of copper, indium, gallium, and selenium) are known to have high efficiency, and can be a top cell candidate by forming a wide gap. However, in a module in which solar cells having different band gaps are joined, the connection method has not been sufficiently studied.

Japanese Patent No. 4599099

  Embodiments provide a solar cell module and a photovoltaic power generation system with improved conversion efficiency.

  The solar cell module according to the embodiment includes a first solar cell panel having a plurality of first submodules including a plurality of first solar cells, a first solar cell panel, and a plurality of second solar cells. A second solar cell panel having a plurality of second submodules included, the first solar cell panel is present on the light incident side, and the first solar cell panel and the second solar cell panel are electrically in parallel; The plurality of first solar cells that are connected and included in the plurality of first submodules are electrically connected in series, the plurality of first submodules are electrically connected in parallel, and the plurality of second submodules The plurality of second solar cells included in is electrically connected in series, and the plurality of second submodules are electrically connected in parallel.

The perspective conceptual diagram of the solar cell module in connection with an embodiment. The schematic diagram of the solar cell panel in connection with embodiment. The schematic diagram of the solar cell panel in connection with embodiment. The schematic diagram of the solar cell panel in connection with embodiment. The schematic diagram of the solar cell panel in connection with embodiment. The perspective conceptual diagram of the solar cell module in connection with an embodiment. The schematic diagram of the solar cell panel in connection with embodiment. The schematic diagram of the solar cell panel in connection with embodiment. The cross-sectional conceptual diagram of the solar cell module in connection with embodiment. The cross-sectional conceptual diagram of the solar cell module in connection with embodiment. The schematic diagram of the solar cell panel in connection with embodiment. The schematic diagram of the solar cell panel in connection with embodiment. The schematic diagram of the solar cell panel in connection with embodiment. The schematic diagram of the solar cell panel in connection with embodiment. The conceptual diagram of the solar cell system in connection with embodiment.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings.
(First embodiment)
The solar cell module of the first embodiment has a structure in which two or more solar cell panels are stacked. Two or more solar cell panels are electrically connected in parallel. As shown in the perspective conceptual view of FIG. 1, the solar cell module 100 according to the present embodiment includes a first solar cell panel 10 and a second solar cell panel 20. The first solar cell panel 10 and the second solar cell panel 20 are stacked in the third direction. The first solar cell panel 10 and the second solar cell panel 20 are electrically connected in parallel. The depth direction of the solar cell module 100 is a first direction, and the width direction of the solar cell module 100 is a second direction. The first direction and the second direction intersect or are orthogonal to each other, and the surface including the first direction and the second direction is parallel to the panel surface of the solar cell module 100. The first direction is orthogonal to the second direction and the third direction, and the second direction is orthogonal to the first direction and the third direction. In addition, an equivalent structure is included if it is the equivalent range of this invention with orthogonal. The third direction is orthogonal to the first direction and orthogonal to the second direction. In the embodiment, two solar cell panels are stacked, but a solar cell module in which three or more solar cell panels are stacked may be used.

  The electric power generated by the first solar cell panel 10 and the second solar cell panel 20 is converted and stored, transmitted, or consumed. Both the electric power generated by the first solar cell panel 10 and the electric power generated by the second solar cell panel 20 need to be converted by a power converter (converter) in order to store, transmit and consume. If the first solar cell panel 10 and the second solar cell panel 20 are converted by different converters, two converters are required. The power generation cost increases due to the increase in the number of converters. Therefore, the solar cell module 100 has only one power output terminal because the panels are electrically connected in parallel even if the number of stacked panels is two or more. Even if the conversion efficiency is improved, if the power generation cost is increased, even if the conversion efficiency is improved by multi-junction, it is not preferable from the viewpoint of recovery of investment funds.

(First solar panel)
The 1st solar cell panel 10 is a panel which exists in the top side of the solar cell module 100, ie, the light incident side. The first solar battery panel 10 has a plurality of solar battery cells each having a wide band gap light absorption layer. Examples of the wide band gap light absorption layer include one or more of a compound semiconductor, a perovskite compound, a transparent oxide semiconductor, and amorphous silicon. The band gap of the light absorption layer having a wide band gap is 1.4 eV or more, preferably 1.4 eV or more and 2.7 eV or less, and more preferably 1.6 eV or more and 2.0 eV or less. Even if the 1st solar cell panel 10 of embodiment is single-piece | unit, it is excellent in conversion efficiency. Therefore, the first solar cell panel 10 of the embodiment is also preferably used as a single solar cell without being stacked with other solar cell panels. The band gap of the light absorption layer is obtained by measuring transmittance and reflectance, obtaining an absorption coefficient, applying to direct transition and indirect transition types, and fitting.

  The first solar cell panel 10 includes a plurality of first submodules 11A including a plurality of first solar cells. The several 1st photovoltaic cell 11 has a structure which makes a 1st direction a longitudinal direction. The plurality of first solar cells 11 arranged in the second direction included in the first submodule 11A are electrically connected in series. The plurality of first submodules 11A are electrically connected in parallel. By adopting a configuration in which the first solar cells 11 are connected in series and in parallel, the conversion efficiency of the solar cell module 100 can be increased. For this purpose, in the first solar cell panel 10 of the embodiment, the number of cells of the first solar cell 11, the cell size, and the output voltage of the first solar cell panel 10 are adjusted.

  The schematic diagram of the 1st solar cell panel 10 is shown in the schematic diagram of FIG. One of the first submodules 11A is surrounded by a broken line. FIG. 3 is a schematic diagram showing the first solar cell panel 10 shown in the schematic diagram of FIG. 2 in a circuit form. In the schematic diagrams of FIGS. 2 and 3, the thin line connecting the first solar cells 11 is an electrical wiring that connects the first solar cells 11 in series. Moreover, in the schematic diagram of FIG. 2, FIG. 3, the thick line which connects the 1st photovoltaic cell 11 is an electrical wiring which connects the 1st photovoltaic cell 11 in parallel. 2 and 3, three first submodules 11 </ b> A in which three solar cells 11 are connected in series are connected in parallel. In the schematic diagrams of FIGS. 2 and 3, the first solar cells 11 are arranged so that the polarities of the first submodules 11A are staggered, but the first solar modules 11A have the same electric polarity. The battery cell 11 may be disposed, and wiring for parallel connection may be further provided.

(Second solar cell panel)
The second solar cell panel 20 is a panel that exists on the bottom side of the solar cell module 100, that is, on the side opposite to the light incident side. The second solar battery panel 20 has a plurality of solar battery cells each having a narrow band gap light absorption layer. Examples of the narrow band gap light absorption layer include a compound semiconductor or Ge. The band gap of the light absorption layer having a narrow band gap is less than 1.4 eV, preferably 0.7 eV or more and less than 1.4 eV, and more preferably 0.7 eV or more and 1.2 eV or less. Even if the 2nd solar cell panel 20 of embodiment is single-piece | unit, it is excellent in conversion efficiency. Therefore, the second solar cell panel 20 of the embodiment is also preferably used as a single solar cell without being stacked with other solar cell panels.

  The second solar cell panel 20 has a plurality of first submodules 11A including a plurality of first solar cells. The several 2nd photovoltaic cell 21 has a structure which makes a 1st direction a longitudinal direction. A plurality of second solar cells 21 arranged in the second direction included in the second submodule 21A are electrically connected in series. The plurality of second submodules are electrically connected in parallel. By adopting a configuration in which the second solar cells 21 are connected in series and in parallel, the conversion voltage of the solar cell module 100 is adjusted by adjusting the output voltage of the first solar cell panel 10 and the output voltage of the second solar cell panel 20. Can be increased. For this purpose, in the second solar battery panel 20 of the embodiment, the number of cells of the second solar battery cell 21, the cell size, and the output voltage of the second solar battery panel 20 are adjusted.

  The schematic diagram of the 2nd solar cell panel 20 is shown in the schematic diagram of FIG. One of the second submodules 21A is surrounded by a broken line. FIG. 5 is a schematic diagram showing the second solar cell panel 20 shown in the schematic diagram of FIG. 4 as a circuit. In the schematic diagrams of FIGS. 4 and 5, the thin line connecting the second solar cells 21 is an electrical wiring that connects the second solar cells 21 in series. Moreover, in the schematic diagram of FIG. 4, FIG. 5, the thick line which connects the 2nd photovoltaic cell 21 is an electrical wiring which connects the 1st photovoltaic cell 21 in parallel. 4 and 5, two second submodules 21 </ b> A in which six solar cells 21 are connected in series are connected in parallel. 4 and 5, the second solar cells 21 are arranged so that the polarities of the second submodules 21A are staggered, but the second solar modules 21A have the same electric polarity. The battery cell 21 may be disposed and a wiring for parallel connection may be provided.

  Hereinafter, the connection form of the photovoltaic cells will be described in more detail. Since the first solar cell panel 10 and the second solar cell panel 20 are connected in parallel, the output voltage difference between the first solar cell panel 10 and the second solar cell panel 20 is preferably small. Therefore, it is preferable that the plurality of first solar cells 11 are electrically connected in series and the plurality of second solar cells 21 are electrically connected in series. The output voltage of the first solar panel 10 and the second solar panel 20 can be matched by changing the number of solar cells connected in series. The difference in output voltage between the first solar cell panel 10 and the second solar cell panel 20 is preferably 2.0 V or less. The smaller the difference between the output voltages, the more the output voltages of the first solar panel 10 and the second solar panel 20 when the first solar panel 10 and the second solar panel 20 are electrically connected in parallel. Less loss due to difference is preferable. Therefore, the difference in output voltage between the first solar cell panel 10 and the second solar cell panel 20 is more preferably 1.5 V or less or 1.0 V or less, and even more preferably 0.5 V or less. The voltage difference between the maximum output point of the first solar cell panel 10 and the maximum output point of the second solar cell panel 20 is preferably 2.0 V or less, preferably 1.5 V or less or 1.0 V or less, and 0.5 V or less. Is more preferable.

  It is possible to reduce the output voltage difference between the first solar panel 10 and the second solar panel 20 by electrically connecting all the solar cells in series in consideration of the open voltage of the solar cells. However, in the first solar battery cell 11 of the first solar battery panel 10, both the upper and lower electrodes need to be transparent electrodes. The transparent electrode has a higher resistance than the metal electrode. Therefore, if the first solar cell 11 and the second solar cell 21 are only electrically connected in series, the number of cells is small and the area of the cell is large. Then, the resistance of the transparent electrode in the cell increases, and the conversion efficiency of the solar battery cell decreases.

  Further, if the width of the first solar cell 11 in the second direction is adjusted in consideration of the resistance of the transparent electrode and all of them are connected in series, the output voltage with the second solar cell panel 20 will not match. Further, for example, if the first solar battery panel 10 is composed of one solar battery cell, the generated voltage difference from the second solar battery panel 10 is greatly different.

Therefore, as described above, the conversion efficiency of the first solar battery cell 11 and the second solar battery cell 21 is increased by connecting the submodules in which the solar battery cells are electrically connected in series electrically in parallel. And it is preferable to make the output voltage difference of the 1st solar cell panel 10 and the 2nd solar cell panel 20 small. By adopting such a configuration, first, the number (range) of solar cells is adjusted so as to be the size of the solar cells so as to be superior in conversion efficiency. Under the condition of this number, the first solar panel 10 and the first solar cell The series number and parallel number of the first solar cells 10 and the series number and parallel number of the second solar cells 21 are selected so that the output voltages of the two solar panel 20 are the same or close to each other. The number of first solar cells 11 is N ₁ , the open circuit voltage is Voc ₁ , the number of series is S ₁ , the number of parallel cells is P ₁ , the number of second solar cells 21 is N ₂ , and the open circuit voltage is Voc _2. When the serial number is S ₂ and the parallel number is P ₂ , N ₁ = S ₁ × P ₁ , N ₂ = S ₂ × P ₂ , 0.9 ≦ (Voc ₁ × S ₁ ) / (Voc ₂ × S ₂ ) ≦ 1.1 is preferably satisfied.

  Even if the high first solar cell panel and the second solar cell panel 20 are electrically connected in parallel by connecting the submodules in which the solar cells are electrically connected in series electrically in parallel, there is no power loss. Since there are few, the solar cell module 100 with high conversion efficiency can be obtained. In the first solar cell panel 10 and the second solar cell panel 20, the parallel number of the plurality of submodules is preferably 2 or more and 10 or less. When the parallel number is small, the area of the transparent electrode per one solar battery cell 11 is large, and the power generation efficiency decreases due to the increase in resistance caused by the transparent electrode. Moreover, when there are too many parallel numbers, the number of the photovoltaic cells 11 in a panel will increase, non-power generation area | regions, such as wiring, will increase, and electric power generation efficiency will fall. In addition, this parallel number is suitably set by the magnitude | size of the 1st solar cell panel 10, and its required characteristic. For example, if the first solar cell panel 10 becomes larger, the number of parallels may increase from the number of parallels described above.

  It is preferable that the number of the series connection of the first solar cells 10 included in each first submodule 11A and the number of the series connection of the second solar cells 20 included in each second submodule are different. By changing the number of series, the difference between the output voltage of the first solar cell panel 10 and the output voltage of the second solar cell panel 20 can be reduced. Since the 1st solar cell panel 10 and the 2nd solar cell panel 20 have the light absorption layer of a different band gap, respectively, the open circuit voltage of each solar cell differs. Since the solar cell module 100 of the embodiment connects the first solar cell panel 10 and the second solar cell panel 20 in parallel, if there is a difference in operating voltage between the two panels, the power output by being connected in parallel. Becomes approximately the lower voltage, and a power loss is caused by the voltage difference. Therefore, in the 1st solar cell panel 10 and the 2nd solar cell panel 20, when the connection structure of the same series number is employ | adopted, according to the difference in the open circuit voltage of a photovoltaic cell, the 1st solar cell panel 10 and the 2nd solar cell panel 20 are. A large difference occurs in the output voltage. The output voltage of the solar battery panel is related to the open circuit voltage of the solar battery cells and the series number thereof. Since the open-circuit voltages of the first solar cells 11 and the second solar cells 21 are different, the number of first solar cells connected in series in the first submodule 11A and the second solar included in the second submodule 21A are different. The number of battery cells 20 connected in series is preferably different.

Here, the first solar battery panel 10 using CGS (Cu _0.95 GaSe _1.95 S _0.05 ) whose Voc (open voltage) is _0.95 V for the light absorption layer of the first solar battery cell 11, The second solar battery panel 20 using polycrystalline CIGS (Cu _0.93 Ga _0.3 In _0.7 Se ₂ ) having a Voc of 0.71 V is laminated on the light absorption layer of the second solar battery cell 21. The solar cell module 100 will be described as an example.

  The number of the 1st photovoltaic cells 11 which used CGSS for the light absorption layer is 168 pieces. 42 first solar cells 11 are electrically connected in series, and four connected first submodules 11A are configured. Four first submodules 11A are electrically connected in parallel. Since CGSS with Voc of 0.95V is used, the first solar cell panel 10 with Voc of 39.9V is obtained. The second solar cell panel 20 is set to Voc39.9V of the first solar cell panel 10. The number of the 2nd photovoltaic cell 21 which used CIGS for the light absorption layer is 168 (183) pieces. 56 (61) second solar cells 21 are electrically connected in series, and three connected second submodules 21A are configured. Three second submodules 21A are electrically connected in parallel. Since VOC is 0.71 (single value, Voc after the first solar panel 10 is mounted is changed to 0.66V), CIGS of V is used, Voc is 39.8 (single value, first solar panel 10 Voc after being changed to 40.3V) becomes the second solar cell panel 20 of V. Since Voc of the obtained 1st solar cell panel 10 and the 2nd solar cell panel 20 is very near, the output voltage of each panel also becomes close and the conversion efficiency of the solar cell module 100 improves. In general, in view of Voc, FF, and the like of the bottom panel when the top panel is mounted, it is better to set the difference in Voc at the maximum output to be small.

(Second Embodiment)
The solar cell module of the second embodiment has a structure in which two or more solar cell panels are stacked. Two or more solar cell panels are electrically connected in parallel. As shown in the perspective conceptual view of FIG. 6, the solar cell module 101 according to this embodiment includes a first solar cell panel 10 and a second solar cell panel 20. The first solar cell panel 10 and the second solar cell panel 20 are stacked in the third direction. The first solar cell panel 10 and the second solar cell panel 20 are electrically connected in parallel. The first solar cell panel 10 includes a first bus bar 12 that connects the first submodule 11A including the first solar cell 11 in the first solar cell panel 10 in parallel. The second solar battery panel 20 includes a second bus bar 22 that connects the second submodule 21A including the second solar battery cell 21 in the second solar battery panel 20 in parallel. The description common to the first embodiment and the second embodiment is omitted.

(Bus bar)
The first bus bar 12 is made of a conductive material such as a metal plate or a metal foil that connects the plurality of first submodules 11A including the first solar cells 11 in parallel in the second direction. The schematic diagram of FIG. 7 shows a schematic diagram of the first solar cell panel 10 of the second embodiment. The first bus bar 12 is a metal wiring extending in the first direction. The first bus bars 12 are arranged side by side in the second direction of the first solar cell panel 10. The first bus bar 12 is disposed between both ends of the first solar cell panel 10 and the plurality of first submodules 11A.

  The second bus bar 22 is a metal plate that connects a plurality of second submodules 21A including the second solar cells 21 in parallel in the second direction. The schematic diagram of FIG. 8 shows a schematic diagram of the second solar cell panel 20 of the second embodiment. The second bus bar 22 is a metal wiring extending in the first direction. The second bus bar 22 is arranged side by side in the second direction of the second solar cell panel 20. The second bus bar 12 is disposed between both ends of the second solar cell panel 20 and the plurality of second submodules 21A.

  The metal used for the first bus bar 12 and the second bus bar 22 is not particularly limited. For example, the first bus bar 12 and the second bus bar 22 are preferably wirings including any one or more metals of Al, Cu, Au, Ag, Mo and W. The widths of the first bus bar 12 and the second bus bar 22 are preferably 1 mm or more and 5 mm or less. If the first bus bar 12 and the second bus bar 22 are too thin, resistance is generated during current collection, which is not preferable. Further, the portion where the first bus bar 12 and the second bus bar 22 are provided is a non-power generation region. Therefore, if the wiring of the first bus bar 12 and the second bus bar 22 is too thick, the amount of power generation is reduced, which is not preferable. Further, the heights of the first bus bar 12 and the second bus bar 22 are not particularly limited. However, if the height is too high, wiring becomes difficult, and therefore it is preferably 2 mm or less or 1 mm or less. Analysis of the solar cell module, such as the height of the first bus bar 12 and the second bus bar 22, can be performed by top surface observation and cross-sectional observation. Perform elemental analysis as necessary.

  9 and 10 are schematic cross-sectional views of the solar cell module 100. FIG. In the schematic diagram of FIG. 9, there are a first solar battery panel 10 having first solar battery cells 11 and a second solar battery panel 20 having second solar battery cells 21. The first solar cell panel 10 shown in the schematic diagram of FIG. 9 includes a plurality of first solar cells including a first bus bar 12, a substrate 13, a first electrode 14, a light absorption layer 15, a buffer layer 16, and a second electrode 17. Cell 11 is included. The second solar cell panel 20 shown in the schematic diagram of FIG. 9 includes a plurality of second solar cells including a second bus bar 22, a substrate 23, a first electrode 24, a light absorption layer 25, a buffer layer 26, and a second electrode 27. A cell 21 is included. P 1, P 2, and P 3 represent side surfaces of cutting by the patterns 1, 2 and 3. Although FIG. 9 illustrates the substrate type substrate configuration, the first solar cell panel 10 and the second solar cell panel 20 may adopt a super straight type substrate configuration. When the super straight type substrate configuration is adopted, the substrate 13 can carry the tempered glass on the light receiving surface side, which leads to a reduction in the weight of the solar cell panel 100. If it is a substrate type substrate configuration, it may be laminated with the second solar cell panel 20 after being coated with a resin if necessary and inverted.

  FIG. 9 is a schematic diagram of three patterns (A), (B), and (C). FIG. 9A shows a form in which the first bus bar 12 is provided on the first electrode 14 of the first solar battery cell 11, and the second bus bar 22 is provided on the first electrode 24 of the second solar battery cell 21. The first electrode 14 of the first solar battery cell 11 exists between the first bus bar 12 and the substrate 13, and the first electrode 24 of the second solar battery cell 21 exists between the second bus bar 22 and the substrate 23. To do.

  FIG. 9B shows a form in which the first bus bar 12 is provided on the second electrode 17 of the first solar battery cell 11, and the second electrode 17 exists between the first bus bar 12 and the light absorption layer 15. To do. In addition, the second bus bar 22 is provided on the second electrode 27 of the second solar battery cell 21, and the second electrode 27 exists between the second bus bar 22 and the light absorption layer 25.

  FIG. 9C shows a form in which the first bus bar 12 is provided on the substrate 13 of the first solar battery cell 11, and the first bus bar 12 exists between the substrate 13 and the first electrode 14. Further, the second bus bar 22 is provided on the substrate 23 of the second solar battery cell 21, and the second bus bar 22 exists between the substrate 23 and the first electrode 24. P4 cut side surfaces exist at both ends of the first bus bar 12 and the second bus bar 22 in the schematic diagram of FIG. 9C. If the bus bar 12 and the second electrode 17 may be a parallel wiring, it is not necessary to form a cross section of P4. 9A, 9B, and 9C, the first solar cells 11 are arranged symmetrically around the first bus bar 12, and the second sub-center around the second bus bar 22. The second solar cells 21 are arranged symmetrically so that the polarities of the modules are staggered. Moreover, in FIG. 9, although the 1st photovoltaic cell 11 and the 2nd photovoltaic cell 21 are exposed, it is preferable to coat | cover this with resin, for example.

FIG. 10 is a schematic diagram of three patterns (A), (B), and (C). In the schematic diagram of FIG. 10, the second solar cell panel 20 is omitted. 10A, 10B, and 10C are arranged so that the polarities of the first solar cells 11 are in the same direction so that the polarities of the first submodules are aligned. . FIG. 10A shows a form in which one bus bar 12 is provided on the first electrode 14 of the first submodule 11A on the left side of the drawing and on the second electrode 17 of the first submodule 11A on the right side of the drawing. . The two bus bars 12 are at least partially overlapped in the third direction. The polarity of the bus bar 12 on the first electrode 14 and the polarity of the bus bar 12 on the second electrode 17 are different. The insulating film 18 is made of resin or SiO ₂ and insulates the two bus bars 12. FIG. 10B shows a form in which one bus bar 12 is provided on each of the first electrode 14 and the insulating film 18 of the first submodule 11A on the left side of the drawing. The bus bar 12 on the insulating film 18 is connected to the first electrode 14 of the first submodule 11A on the right side of the drawing. The two bus bars 12 are at least partially overlapped in the third direction. The polarity of the bus bar 12 on the first electrode 14 and the bus bar 12 on the insulating film 18 have different polarities. FIG. 10C shows a form in which one bus bar 12 is provided on the first electrode 14 of the first submodule 11A on the left side of the drawing and on the first electrode 14 of the first submodule 11A on the right side of the drawing. . The two bus bars 12 are arranged side by side in the second direction. The polarity of the bus bar 12 on the first electrode 14 of the first submodule 11A on the left side of the drawing is different from the polarity of the bus bar 12 on the first electrode 14 of the first submodule 11A on the right side of the drawing. Moreover, in FIG. 10, although the 1st photovoltaic cell 11 is exposed, it is preferable to coat | cover this with resin, for example.

(substrate)
As the substrates 13 and 23 of the embodiment, soda lime glass is desirably used, and general glass such as quartz, white plate glass, and chemically tempered glass, or resins such as polyimide and acrylic can also be used.

(First electrode)
The first electrode 14 of the first solar cell 11 of the embodiment is an electrode of the first solar cell 10. For example, the first electrode 14 is a transparent electrode including a semiconductor film formed on the substrate 13. The first electrode 14 exists between the substrate 13 and the light absorption layer 15. The first electrode 14 may include a thin metal film. As the first electrode 14, a semiconductor film containing at least indium tin oxide (ITO) can be used. A layer containing an oxide such as SnO ₂ , TiO ₂ , carrier-doped ZnO: Ga, or ZnO: Al may be stacked on the ITO on the light absorption layer 15 side. It may be a laminate of ITO and SnO ₂ from the substrate 13 side to the light absorption layer 15 side, or a laminate of ITO, SnO ₂ and TiO ₂ from the substrate 13 side to the light absorption layer 15 side. The layer in contact with the light absorption layer of the first electrode 14 is preferably an oxide layer of any one of ITO, SnO ₂ and TiO ₂ . Further, a layer containing an oxide such as SiO ₂ may be further provided between the substrate 13 and the ITO. The first electrode 14 can be formed by sputtering the substrate 13 or the like. The film thickness of the first electrode 14 is, for example, not less than 100 nm and not more than 1000 nm. When the solar cell of the embodiment is used for a multi-junction solar cell, the solar cell of the embodiment is present on the top cell side or the middle cell side, and the first electrode 14 is a light-transmitting semiconductor film. preferable. The 1st electrode 24 of the 2nd photovoltaic cell 21 may be the same as the 1st electrode 14 of the 1st photovoltaic cell 11, and metal films, such as Mo and W, may be sufficient as it.

(Light absorption layer)
The light absorption layer 15 of the first solar battery cell 11 according to the embodiment is one or more of a compound semiconductor, a perovskite compound, a transparent oxide semiconductor, and amorphous silicon. The light absorption layer 15 is a layer that forms a pn junction with the buffer layer 16. If the light absorption layer 15 is p-type, the buffer layer is n-type. If the light absorption layer 15 is n-type, the buffer layer 16 is p-type. The light absorption layer 15 exists between the first electrode 14 and the buffer layer 16. When the light absorption layer 15 is a homojunction type, the buffer layer 16 may be omitted.

The light absorption layer 15 is a compound having a chalcopyrite structure such as CuGaSe ₂ , Cu (Al, Ga) (S, Se) ₂ , CuGa (S, Se) ₂ , Cu (In, Ga) (S, Se) ₂ . A semiconductor layer or a compound semiconductor layer such as CdTe, (Cd, Zn, Mg) (Te, Se, S) or (In, Ga) ₂ (S, Se, Te) ₃ can be used as the light absorption layer. The film thickness of the light absorption layer 15 is, for example, not less than 800 nm and not more than 3000 nm.

The light absorption layer 15 is preferably made of an oxide transparent semiconductor such as Cu ₂ O.

  By combining the elements, the size of the band gap can be easily adjusted to a target value. The target band gap value is, for example, 1.0 eV or more and 2.7 eV or less.

It is preferable that the band gap value of the light absorption layer 15 on the top cell side is large from the viewpoint of increasing the power generation amount in the second solar cell on the bottom cell side by widening the band gap of the light absorption layer 15 on the top cell side. As the light absorption layer 15 having a larger band gap, Cu ₂ O, (Cd, Zn, Mg) (Te, Se, S), (In, Ga) ₂ (S, Se, Te) _{3 and the} like absorb light. Suitable for layer 15.

In addition, the light absorption layer 15 may be a perovskite type compound or amorphous silicon layer represented by CH ₃ NH ₃ PbX ₃ (X is at least one halogen).

The light absorption layer 25 of the second solar battery cell 21 of the embodiment is preferably a layer using any one of a compound semiconductor, an oxide transparent semiconductor, a perovskite compound, and a compound containing Ge. As the compound semiconductor, a compound semiconductor having a chalcopyrite structure represented by Cu (In, Ga) Se ₂ , CuInTe ₂ , Cu (In, Al) Se ₂ , Ag (In, Ga) Se ₂ , and others Examples thereof include a compound semiconductor layer having a kesterite structure or a stannite structure represented by CZTS (Cu ₂ ZnSnS ₄ ) or CZTSS (Cu ₂ ZnSnSe _4−x S _x ). CuO etc. are mentioned as an oxide transparent semiconductor. Examples of the perovskite compound include CH ₃ NH ₃ PbX ₃ (X is at least one halogen). The light absorption layer 25 of the second solar cell 21 is common to the light absorption layer 15 of the first solar cell 21 except for the composition of the compound and the like. The light absorption layer 25 of the second solar battery cell 21 has a narrower band gap than the light absorption layer 15 of the first solar battery cell 11.

(Buffer layer)
The buffer layers 16 and 26 of the embodiment are n-type or p-type semiconductor layers. The buffer layers 16 and 26 exist between the light absorption layers 15 and 25 and the second electrodes 17 and 27. The buffer layers 16 and 26 are layers in physical contact with the surface of the light absorption layers 15 and 25 opposite to the surface facing the first electrodes 14 and 24 side. The buffer layers 16 and 26 are layers that are heterojunction with the light absorption layers 15 and 25. The buffer layers 16 and 26 are preferably an n-type semiconductor or a p-type semiconductor whose Fermi level is controlled so that a solar cell with a high open-circuit voltage can be obtained.

When the light absorption layers 15 and 25 are chalcopyrite type compounds, kesterite type compounds, or stannite type compounds, the buffer layers 16 and 26 are, for example, Zn _1-y M _y O _1-x S _x , Zn _{1-y- z} Mg _z M _y O, ZnO _1-x S _x , Zn _1-z Mg _z O (M is at least one element selected from the group consisting of B, Al, In, and Ga), CdS, and the like are used. it can. The thickness of the buffer layers 16 and 26 is preferably 2 nm or more and 800 nm or less. The buffer layers 16 and 26 are formed by sputtering or CBD (Chemical Solution Deposition), for example. When the buffer layers 166 and 26 are formed by CBD, for example, a metal salt (for example, CdSO ₄ ), a sulfide (thiourea) and a complexing agent (ammonia) are chemically reacted with each other on the light absorption layers 15 and 25 in an aqueous solution. Can be formed. When a chalcopyrite compound containing no In in the IIIb group element, such as a CuGaSe ₂ layer, an AgGaSe ₂ layer, a CuGaAlSe ₂ layer, or a CuGa (Se, S) ₂ layer, is used for the light absorption layer 15, the buffer layers 16 and 26 CdS is preferred.

When the light absorption layer 25 is Ge, the buffer layer 26 is preferably made of, for example, ZnO _X.

  When the light absorption layer 15 is a perovskite type compound, the buffer layer 16 is an n-type layer called a so-called compact layer. The compact layer is preferably a layer of one or more oxides selected from titanium oxide, zinc oxide, gallium oxide, and the like.

  When the light absorption layer 15 is amorphous silicon, the buffer layer 16 is preferably made of amorphous SiC: H having a wide gap and close properties.

(Oxide layer)
The oxide layer of the embodiment is a thin film that is preferably provided between the buffer layers 16 and 26 and the second electrodes 17 and 27. The oxide layer is a thin film containing any one compound of Zn _1-x Mg _x O, ZnO _1-y S _y and Zn _1-x Mg _x O _1-y S _y (0 ≦ x, y <1). is there. The oxide layer may not cover all the surfaces of the buffer layers 16 and 26 facing the second electrodes 17 and 27. For example, it is only necessary to cover 50% of the surface of the buffer layers 16 and 26 on the second electrode 17 side. Other candidates include AlO _Z , SiO _Z , SiN _Z , Wurtz-type AlN, GaN, BeO, and the like. When the volume resistivity of the oxide layer is 1 Ωcm or more, there is an advantage that leakage current derived from a low resistance component that may exist in the light absorption layer 15 can be suppressed. In the embodiment, the oxide layer can be omitted. These oxide layers are oxide particle layers, and preferably have a large number of voids in the oxide layer. The intermediate layer is not limited to the above-described compounds and physical properties, and may be any layer that contributes to improving the conversion efficiency of the solar cell. The intermediate layer may be a plurality of layers having different physical properties.

(Second electrode)
The second electrodes 17 and 27 of the embodiment are electrode films that transmit light such as sunlight and have conductivity. The second electrodes 17 and 27 are in physical contact with the surface of the intermediate layer or the buffer layers 16 and 26 opposite to the surface facing the light absorption layer 15 side. Between the second electrodes 17, 27 and the first electrode 14, there are the light absorption layers 15, 25 and the buffer layers 16, 26 joined. For example, the second electrodes 17 and 27 are formed by sputtering in an Ar atmosphere. As the second electrodes 17 and 27, for example, ZnO: Al using a ZnO target containing 2 wt% of alumina (Al ₂ O ₃ ) or ZnO: B using B from a diborane or triethylboron as a dopant can be used. .

(Third electrode)
The third electrode of the embodiment is an electrode of the first solar cell 11 or the second solar cell 21, and is a metal film formed on the side opposite to the light absorption layers 15 and 25 side on the second electrode. is there. As the third electrode, a conductive metal film such as Ni or Al can be used. The film thickness of the third electrode is, for example, not less than 200 nm and not more than 2000 nm. The third electrode may be omitted when the resistance values of the second electrodes 17 and 27 are low and the series resistance component can be ignored.

(Antireflection film)
The antireflection film of the embodiment is a film for facilitating the introduction of light into the light absorption layers 15 and 25, and the light absorption layers 15 and 25 side on the second electrodes 17 and 28 or the third electrode It is formed on the opposite side. It is preferable to provide an antireflection film between the first solar cell panel 10 and the second solar cell panel 20. For example, MgF ₂ or SiO ₂ is preferably used as the antireflection film. In the embodiment, the antireflection film can be omitted. Although it is necessary to adjust the film thickness according to the refractive index of each layer, it is preferable to deposit 70-130 nm (80-120 nm). In place of the antireflection film, a dichroic mirror that reflects a short wavelength and transmits a long wavelength is preferably provided between the first solar cell panel 10 and the second solar cell panel 20. Providing a dichroic mirror is preferable in that the light absorption layer on the top cell side can be thinned.

  The production method of the first solar battery cell 11 and the side faces P1, P2, and P3 cut by the patterns 1, 2, and 3 will be briefly described. A first electrode 14 is formed on the substrate 13, and the first electrode 14 is scribed to form a cross section P1. Subsequently, the light absorption layer 15 and the buffer layer 16 are formed. The light absorption layer 15 is also formed on the cross section of P1. The light absorption layer 15 and the buffer layer 16 are scribed to form a cross section P2. Subsequently, the second electrode 17 is formed on the buffer layer 16. The second electrode 17 is also formed on the cross section of P2. Then, when scribing is performed on the light absorption layer 15, the buffer layer 16, and the second electrode 17, a cross section of P3 is formed. And the 1st photovoltaic cell 11 connected in series is obtained. The bus bar 12 may be formed on the substrate before the first electrode 14 is formed, or may be formed before or after the scribing process for forming the cross section of P3. The production method and the patterns 1, 2, and 3 of the second solar cell 21 are common to the production method and the patterns 1, 2, and 3 of the first solar cell 21.

  Since both the first electrode 14 and the second electrode 17 of the first solar battery cell 11 are transparent electrodes that transmit light, the resistance tends to be higher than that of the metal film electrode. For this reason, when the areas of the first electrode 14 and the second electrode 17 are large, the influence of the high resistance of the electrodes becomes significant. The small solar cell panel is about 1200 mm × 600 mm, and the large one is about 1600 mm × 1000 mm. Since the solar cell panel 10 has a large area, the first electrode 14 and the second electrode 17 per one of the first solar cells 11 also have a large area if they are simply connected in series. In the embodiment, the area of the transparent electrode can be reduced by electrically connecting the submodules in parallel. If the area of the transparent electrode is reduced, the number of sub-modules connected in parallel increases accordingly, and the non-power generation area increases. Therefore, it is not preferable to make the area of the transparent electrode too small. Moreover, the electricity generated by the cell flows in the width direction (short direction) which is the second direction of the solar battery cell. Therefore, the influence of the resistance of the transparent electrode can be reduced by shortening the distance in the width direction of the transparent electrode. Therefore, the width of the first electrodes 14, 24, the width of the second electrodes 17, 27, or the width of the first electrodes 14, 24 and the second electrodes 17, 27 is preferably 3 mm or more and 15 mm or less. .3 mm or more and 8 mm or less is more preferable, and 3.5 mm or more and 8 mm or less is more preferable. The widths of the first electrodes 14 and 24 are distances in the second direction of the surfaces of the first electrodes 14 and 24 facing the substrates 13 and 24. Similarly, the widths of the second electrodes 17 and 27 are distances in the second direction of the surfaces of the second electrodes 17 and 27 facing the substrates 13 and 23.

(Third embodiment)
The solar cell module of the third embodiment is laminated with a first solar cell panel in which a plurality of first submodules including a plurality of first solar cells are electrically connected by a bus bar, and the first solar cell panel, A plurality of second submodules including a plurality of second solar cells have a second solar cell panel having a second solar cell panel electrically connected by a bus bar. The two solar cell panels are preferably electrically connected in parallel. FIG. 11 shows a schematic diagram of the first solar cell panel 20 of the third embodiment, and FIG. 12 shows a schematic diagram of the second solar cell panel 20 of the third embodiment. The panels of FIGS. 11 and 12 are rectangular in size. The longitudinal direction of the first submodule 11A is the same direction as the longitudinal direction of the first solar cell in the first submodule 11A. The longitudinal direction of the second submodule 21A is the same as the longitudinal direction of the second solar cell in the second submodule 21A.

  In the first solar cell panel 10 of FIG. 11, first submodules 11A having the first direction as the longitudinal direction are arranged. A first bus bar 12 is connected between and at both ends of the first sub module 11 </ b> A, and the power generated by the first sub module 11 </ b> A is taken out by the first bus bar 12. In the schematic diagram of FIG. 11, a plurality of sets in which three first submodules 11A are electrically connected in parallel by the first bus bar 12 are shown. The number of first submodules 11A and the like can be appropriately selected according to the size and shape of the panel.

  In the second solar cell panel 20 of FIG. 12, second submodules 21A having the second direction as the longitudinal direction are arranged. A second bus bar 22 is connected between and at both ends of the second sub module 21 </ b> A, and the power generated by the second sub module 21 </ b> A is taken out by the second bus bar 22. A region surrounded by a broken line in FIG. 12 is a region 28 in which a shadow generated by the first bus bar 12 covers the second solar cell panel 20 when light is irradiated perpendicularly to the first solar cell panel 10. Represents. In the schematic diagram of FIG. 12, a plurality of sets in which two second submodules 21A are electrically connected in parallel by the second bus bar 22 are shown. The number of second submodules 21A and the like can be appropriately selected according to the size and shape of the panel.

  The first bus bar 12 of the first solar battery panel 10 exists so as to straddle the short direction of the second solar battery cell 21 of the second solar battery panel 20. Accordingly, the regions 28 that are the shadows of all the second solar cells 21 are substantially equal. The area part of the area | region 28 which becomes the shadow of the 2nd photovoltaic cell 21 becomes a non-electric power generation area | region. When the non-power generation area of each second solar battery cell 21 is equal, the influence on power generation by the second solar battery panel 20 can be reduced. For example, if the shadow caused by the first bus bar 12 completely covers one of the second solar cells 21, the power generation amount of the second solar cell 21 becomes 0, and the power generation amount The power generation amount of the submodule in which the second solar cells 21 having 0 are connected in series also becomes zero. However, if the shadow generated by the first bus bar 12 covers the second solar cells 21 partially evenly, the power generation amount in all the second solar cells 21 is reduced to the same extent. The power generation amount of the module 21A is reduced only by the area of the shaded area. Even if the size and direction of the submodule are not aligned and the direction of the bus bar 12 is not aligned, the first bus bar 12 is unlikely to be a shadow of the second solar cell 21. The first solar cell panel 10 can be configured to increase the arrival of light to the power generation region of the second solar cell panel 20. Even in such a configuration, the first solar cell panel 10 and the second solar cell panel 20 can be connected in parallel with low loss by aligning the power generation voltages of the first solar cell panel 10 and the second solar cell panel 20.

(Fourth embodiment)
The solar cell module according to the fourth embodiment includes a first solar cell panel in which a plurality of first submodules including a plurality of first solar cells are electrically connected by a bus bar, and a first solar cell panel stacked with the first solar cell panel. 2 solar panels. The solar cell module of the fourth embodiment is a modification of the solar cell module of the third embodiment. The two solar cell panels are preferably electrically connected in parallel. FIG. 13 shows a schematic diagram of the first solar cell panel 20 of the fourth embodiment, and FIG. 14 shows a schematic diagram of the second solar cell panel 20 of the fourth embodiment. The panels of FIGS. 13 and 14 are polygonal shapes of the same size. When a solar cell module is arranged on a roof or the like, if the area to be arranged is not rectangular, the installation area (effective area) of the solar cell module can be efficiently expanded by using the module of this embodiment.

  The solar cell module of the fourth embodiment is common to the solar cell module of the third embodiment except that the shape of the panel and the arrangement or configuration of the submodules are different.

  When the panel shape is a polygon, if the submodule is arranged so that one direction is the longitudinal direction in each panel as in the third embodiment, the submodule may partially protrude from the panel, or non-power generation An area | region increases and a photovoltaic cell (submodule) cannot be arrange | positioned efficiently. Therefore, when the panel shape is other than a rectangle such as a polygon, the submodules can be efficiently arranged on the panel by changing the arrangement and configuration of the submodules as shown in the schematic diagrams of FIGS.

  In the first solar cell panel 10 shown in the schematic diagram of FIG. 13, three first submodules 11A1 whose longitudinal direction is the first direction on the right side of the panel in the drawing and the second direction on the left side of the panel in the drawing are the longitudinal direction. By combining the three first submodules 11A2, the polygonal shape and the arrangement of the submodules are matched. The three submodules are electrically connected in parallel. The aspect ratios of the three first submodules 11A connected in parallel are different. By adjusting any of the size, aspect ratio, arrangement direction, number, and position of the first submodule 11A, it is possible to arrange the first submodule 11A in accordance with the shape of the panel.

  In the second solar cell panel 20 shown in the schematic diagram of FIG. 14, two second submodules 21 </ b> A <b> 1 whose longitudinal direction is the second direction on the right side of the panel in the drawing and the first direction on the left side of the panel in the drawing are the longitudinal direction. By combining the two second submodules 21A2, the polygonal shape and the arrangement of the submodules are matched. The two submodules are electrically connected in parallel. The aspect ratios of the two second submodules 21A connected in parallel are different. By adjusting any one of the size, aspect ratio, arrangement direction, number, and position of the second submodule 21A, it is possible to arrange the second submodule 21A in accordance with the shape of the panel.

  Even if the solar panels of FIGS. 13 and 14 are overlapped, the bus bar 12 of the first solar panel 10 reduces the amount of power generated in the second solar cell 21 of the second solar panel 20 as in the third embodiment. The influence on is suppressed. Even if the orientation of the sub modules is not aligned and the orientation of the bus bar 12 is not aligned, the bus bar 12 is unlikely to be a shadow of the second solar cell 21. The first solar cell panel 10 can be configured to increase the arrival of light to the power generation region of the second solar cell panel 20. Even in such a configuration, the first solar cell panel 10 and the second solar cell panel 20 can be connected in parallel with low loss by aligning the power generation voltages of the first solar cell panel 10 and the second solar cell panel 20.

(Fifth embodiment)
The solar cell modules 100 and 101 (including the third embodiment and the fourth embodiment) of the embodiment can be used as a power generator that generates power in the solar power generation system of the third embodiment. The solar power generation system according to the embodiment generates power using a solar cell module. Specifically, the solar cell module that generates power, means for converting the generated electricity, and the generated electricity A storage unit for storing electricity or a load for consuming the generated electricity. FIG. 15 shows a conceptual diagram of the configuration of the photovoltaic power generation system 200 of the embodiment. The solar power generation system of FIG. 15 includes a solar cell module 201 (100, 101, 102), a converter 202, a storage battery 203, and a load 204. Either the storage battery 203 or the load 204 may be omitted. The load 204 may be configured to be able to use electrical energy stored in the storage battery 203. The converter 202 is a device including a circuit or an element that performs power conversion such as transformation or DC / AC conversion, such as a DC-DC converter, a DC-AC converter, and an AC-AC converter. As the configuration of the converter 202, a suitable configuration may be adopted according to the generated voltage, the configuration of the storage battery 203 and the load 204.

  The solar cells included in the received solar cell module 201 generate power, and the electric energy is converted by the converter 202 and stored in the storage battery 203 or consumed by the load 204. The solar cell module 201 is provided with a solar light tracking drive device for always directing the solar cell module 201 toward the sun, a condensing body for condensing sunlight, a device for improving power generation efficiency, and the like. It is preferable to add.

  The solar power generation system 200 is preferably used for real estate such as a residence, a commercial facility, a factory, or used for movable property such as a vehicle, an aircraft, or an electronic device. By using the photoelectric conversion element excellent in conversion efficiency of the embodiment for the solar cell module 201, an increase in the amount of power generation is expected.

EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not limited to a following example.
Example 1
Example 1 uses Cu _0.95 GaSe _1.82 S _0.18 for the light absorption layer of the first solar battery cell of the first solar battery panel, and the light absorption of the second solar battery cell of the second solar battery panel. Cu _0.95 In _0.7 Ga _0.3 Se ₂ is used for the layer. The first solar cell panel and the second solar cell panel are 1650 mm in the first direction and 991 mm in the second direction. The first solar cells all have the same 4.5 mm width and are provided in 216 rows in the second direction. 72 first cells are electrically connected in series to form three first submodules. A total of four 3 mm bus bars are provided between and at both ends of the three first submodules, and are electrically connected in parallel. All the second solar cells have the same width of 3.5 mm and are provided in 276 rows in the second direction. Two second submodules are formed by electrically connecting 138 cells in series. A total of three 3 mm bus bars are provided between the two second submodules and at both ends, and are electrically connected in parallel.

  First, separately obtain the Jsc, Voc, and conversion efficiency for the first solar cell panel and the second solar cell panel, and then stack the first solar cell panel and the second solar cell panel in parallel electrically. The conversion efficiency of the connected solar cell module is obtained. The results of other examples and comparative examples are also shown in Table 1.

(Comparative Example 1)
The first solar cells all have the same 4.5 mm width and are provided in 216 rows in the second direction. One first submodule is formed by electrically connecting 216 cells in series. Bus bars are provided at both ends of the panel, and the first solar cells are electrically connected in series. All the second solar cells have the same width of 3.5 mm and are provided in 276 rows in the second direction. One second submodule is formed by electrically connecting 276 cells in series. Bus bars are provided at both ends of the panel, and the second solar cells are electrically connected in series. Except for these, the second embodiment is the same as the first embodiment.

(Comparative Example 2)
The first solar cells all have the same 13.6 mm width and are provided in 72 rows in the second direction. One first submodule is formed by electrically connecting 72 cells in series. Bus bars are provided at both ends of the panel, and the first solar cells are electrically connected in series. All the second solar cells have the same width of 7.0 mm and are provided in 138 rows in the second direction. One second submodule is formed by electrically connecting 138 cells in series. Bus bars are provided at both ends of the panel, and the second solar cells are electrically connected in series. Except for these, the second embodiment is the same as the first embodiment.

(Example 2)
The first solar cells all have the same 6.1 mm width and are provided in 159 rows in the second direction. Three first submodules are formed by electrically connecting 53 cells in series. A total of four bus bars are provided between and at both ends of the three first submodules, and are electrically connected in parallel. All the second solar cells have the same width of 4.8 mm and 200 rows are provided in the second direction. Two second submodules are formed by electrically connecting 100 cells in series. A total of three bus bars are provided between and at both ends of the two second submodules, and are electrically connected in parallel. Except for these, the second embodiment is the same as the first embodiment.

(Example 3)
The first solar cells all have the same 8.4 mm width and are provided in 115 rows in the second direction. Twenty-three cells are electrically connected in series to form five first submodules. A total of six bus bars are provided between and at both ends of the five first submodules, and are electrically connected in parallel. The second solar cells all have the same 11 mm width and are provided in 88 rows in the second direction. 44 cells are electrically connected in series to form two second submodules. A total of three bus bars are provided between and at both ends of the two second submodules, and are electrically connected in parallel. Except for these, the second embodiment is the same as the first embodiment.

Example 4
The first solar cells all have the same 8.4 mm width and are provided in 115 rows in the second direction. Twenty-three cells are electrically connected in series to form five first submodules. A total of six bus bars are provided between and at both ends of the five first submodules, and are electrically connected in parallel. All the second solar cells have the same width of 7.4 mm and are provided in 132 rows in the second direction. 44 cells are electrically connected in series to form three second submodules. A total of four bus bars are provided between and at the ends of the three second submodules, and are electrically connected in parallel. Except for these, the second embodiment is the same as the first embodiment.

(Example 5)
The first solar cells all have the same 13 mm width and are provided in 75 rows in the second direction. Twenty-five cells are electrically connected in series to form three first submodules. A total of four bus bars are provided between and at both ends of the three first submodules, and are electrically connected in parallel. The second solar cells all have the same width of 6.9 mm and are provided in 141 rows in the second direction. 47 cells are electrically connected in series to form three second submodules. A total of four bus bars are provided between and at the ends of the three second submodules, and are electrically connected in parallel. Except for these, the second embodiment is the same as the first embodiment.

(Example 6)
The first solar cells all have the same width of 14 mm and are provided in 69 rows in the second direction. Three first submodules are formed by electrically connecting 23 cells in series. A total of four bus bars are provided between and at both ends of the three first submodules, and are electrically connected in parallel. All the second solar cells have the same width of 7.4 mm and are provided in 132 rows in the second direction. 44 cells are electrically connected in series to form three second submodules. A total of four bus bars are provided between and at the ends of the three second submodules, and are electrically connected in parallel. Except for these, the second embodiment is the same as the first embodiment.

(Example 7)
The first solar cells all have the same 15 mm width and are provided in 63 rows in the second direction. 21 cells are electrically connected in series to form three first submodules. A total of four bus bars are provided between and at both ends of the three first submodules, and are electrically connected in parallel. All the second solar cells have the same 8.1 mm width and 120 rows are provided in the second direction. Forty cells are electrically connected in series to form three second submodules. A total of four bus bars are provided between and at the ends of the three second submodules, and are electrically connected in parallel. Except for these, the second embodiment is the same as the first embodiment.

(Example 8)
Cu _0.95 GaSe ₂ is used for the light absorption layer of the first solar battery cell of the first solar battery panel. The first solar cells all have the same width of 5.4 m and are provided in 180 rows in the second direction. Sixty first cells are formed by connecting 60 cells electrically in series. A total of four bus bars are provided between and at both ends of the three first submodules and are electrically connected in parallel. Using _Cu 0.96 _{In 0.59} Ga _0.41 Se ₂ on the light-absorbing layer of the second solar cell of the second solar cell panel. The second solar cells all have the same width of 5.9 mm and are provided in 164 rows in the second direction. 82 cells are electrically connected in series to form two second submodules. A total of three bus bars are provided between and at both ends of the two second submodules, and are electrically connected in parallel. Except for these, the second embodiment is the same as the first embodiment. (The Voc of the second solar cell is 0.705 with the top cell)

Example 9
Cu _0.95 GaSe ₂ is used for the light absorption layer of the first solar battery cell of the first solar battery panel. The first solar cells all have the same 6.1 mm width and are provided in 160 rows in the second direction. Two first submodules are formed by electrically connecting 80 cells in series. A total of three bus bars are provided between the two first submodules and at both ends, and are electrically connected in parallel. Using _Cu 0.96 _{In 0.59} Ga _0.41 Se ₂ on the light-absorbing layer of the second solar cell of the second solar cell panel. The second solar cells all have the same width of 4.5 mm and are provided in 216 rows in the second direction. Two second submodules are formed by electrically connecting 108 cells in series. A total of three bus bars are provided between and at both ends of the two second submodules, and are electrically connected in parallel. Except for these, the second embodiment is the same as the first embodiment.

(Example 10)
CH ₃ NH ₃ Pb (I, Cl) ₃ is used as the perovskite compound in the light absorption layer of the first solar battery cell of the first solar battery panel. The first solar cells all have the same 8.1 mm width and 120 rows are provided in the second direction. Forty cells are electrically connected in series to form three first submodules. A total of four bus bars are provided between and at both ends of the three first submodules and are electrically connected in parallel. Using _Cu 0.96 _In 0.59 _{Ga 0.41} Se ₂ on the light-absorbing layer of the second solar cell of the second solar cell panel. The second solar cells all have the same width of 7.8 mm and are provided in 124 rows in the second direction. Two second submodules are formed by electrically connecting 62 cells in series. A total of three bus bars are provided between and at both ends of the two second submodules, and are electrically connected in parallel. Except for these, the second embodiment is the same as the first embodiment.

(Example 11)
Amorphous silicon is used for the light absorption layer of the first solar battery cell of the first solar battery panel. The first solar cells all have the same 8.1 mm width and 120 rows are provided in the second direction. Forty cells are electrically connected in series to form three first submodules. A total of four bus bars are provided between and at both ends of the three first submodules and are electrically connected in parallel. Using _Cu 0.96 _In 0.59 _{Ga 0.41} Se ₂ on the light-absorbing layer of the second solar cell of the second solar cell panel. The second solar cells all have the same 6.2 mm width and are provided in 156 rows in the second direction. 52 cells are electrically connected in series to form three second submodules. A total of four bus bars are provided between and at the ends of the three second submodules, and are electrically connected in parallel. Except for these, the second embodiment is the same as the first embodiment.

(Example 12)
Amorphous silicon is used for the light absorption layer of the first solar battery cell of the first solar battery panel. The first solar cells all have the same 8.1 mm width and 120 rows are provided in the second direction. Forty cells are electrically connected in series to form three first submodules. A total of four bus bars are provided between and at both ends of the three first submodules and are electrically connected in parallel. Using _Cu 0.96 _In 0.59 _{Ga 0.41} Se ₂ on the light-absorbing layer of the second solar cell of the second solar cell panel. All the second solar cells have the same width of 9.4 mm and are provided in 104 rows in the second direction. 52 cells are electrically connected in series to form two second submodules. A total of three bus bars are provided between and at both ends of the two second submodules, and are electrically connected in parallel. Except for these, the second embodiment is the same as the first embodiment.

(Example 13)
Amorphous silicon is used for the light absorption layer of the first solar battery cell of the first solar battery panel. The first solar cells all have the same 8.1 mm width and 120 rows are provided in the second direction. Forty cells are electrically connected in series to form three first submodules. A total of four bus bars are provided between and at both ends of the three first submodules and are electrically connected in parallel. Cu _1.87 Zn _1.02 Sn _0.99 Se _0.07 S _3.93 is used for the light absorption layer of the second solar battery cell of the second solar battery panel. All the second solar cells have the same width of 6.8 mm and are provided in 144 rows in the second direction. Two second submodules are formed by electrically connecting 72 cells in series. A total of three bus bars are provided between the two second submodule groups and at both ends, and are electrically connected in parallel. Except for these, the second embodiment is the same as the first embodiment.

Efficiency is increased by setting the first and second parallel numbers to optimum values.
If you try to force the same number of parallel lines and widen the scribe width, the efficiency of a single unit will drop. Therefore, the total efficiency (output) is lowered.

Further, as a light absorbing layer of the first solar _{cell, Cu 2 O, (Cd,} Zn, Mg) (Te, Se, S) and _{(In, Ga) 2 (S} , Se, Te) 3 , such as a solar cell By using a light absorption layer having a very wide band gap, the band gap difference between the bottom second solar cell and the light absorption layer can be further increased. As the difference in the band gap is larger, the light that contributes to the power generation of the light absorption layer of the second solar cell reaches and the power generation amount increases. By adopting such a multi-junction solar cell with a large difference in band gap and adopting the connection form of the embodiment, the amount of power generation in the second solar cell panel on the bottom cell side increases, and the multi-junction solar cell A further increase in power generation in the battery is expected. In the specification, some elements are represented only by element symbols.

  The embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, you may combine suitably the component covering different embodiment like a modification.

DESCRIPTION OF SYMBOLS 100, 101, 102 ... Solar cell, 10 ... 1st solar cell panel, 11 ... 1st photovoltaic cell, 11A ... 1st submodule, 12 ... 1st bus bar, 13 ... Board | substrate, 14 ... 1st electrode, 15 ... Light absorption layer, 16 ... buffer layer, 17 ... second electrode, 18 ... insulating film, 20 ... second solar battery panel, 21 ... second solar battery cell, 21A ... second submodule, 22 ... second bus bar, 23 ... Substrate, 24 ... first electrode, 25 ... light absorption layer, 26 ... buffer layer, 27 ... second electrode, 28 ... shadow region, 200 ... solar cell system, 201 ... solar cell module, 202 ... converter, 203 ... Storage battery, 204 ... load

Claims (11)

A first solar panel having a plurality of first submodules including a plurality of first solar cells;
A second solar panel having a plurality of second submodules laminated with the first solar panel and including a plurality of second solar cells;
The first solar cell panel exists on the light incident side,
The first solar cell panel and the second solar cell panel are electrically connected in parallel,
The plurality of first solar cells included in the plurality of first submodules are electrically connected in series,
The plurality of first sub-modules are electrically connected in parallel;
The plurality of second solar cells included in the plurality of second submodules are electrically connected in series,
A solar cell module in which the plurality of second submodules are electrically connected in parallel. The plurality of first solar cells have a structure in which a first direction is a longitudinal direction,
The first solar cells included in the first submodule are electrically connected in series in a second direction intersecting the first direction,
The first submodule is electrically connected in parallel in the second direction;
The plurality of second solar cells have a structure in which the first direction is a longitudinal direction,
The second solar cells included in the second submodule are electrically connected in series in the second direction,
The second submodule is a solar cell module electrically connected in parallel in the second direction.   The solar cell module according to claim 1 or 2, wherein a difference in output voltage between the first solar cell panel and the second solar cell panel is 2.0 V or less.   The plurality of first solar cells according to any one of claims 1 to 3, wherein any one or more of a compound semiconductor, a perovskite compound, a transparent oxide semiconductor, and amorphous silicon is used for the light absorption layer. The solar cell module described. The plurality of second solar cells have a light absorption layer using any one of a compound semiconductor, an oxide transparent semiconductor, a perovskite compound, and a compound containing Ge,
5. The solar cell according to claim 1, wherein the band gaps of the light absorption layers of the plurality of second solar cells are narrower band gaps than the light absorption layers of the plurality of first solar cells. module.   The number of series connection of the said 1st photovoltaic cell contained in each said 1st submodule and the number of series connection of the said 2nd photovoltaic cell contained in each said 2nd submodule are different from any one of Claim 1 thru | or 5. The solar cell module according to item. The plurality of first submodules are electrically connected in parallel by a bus bar,
The solar cell module according to any one of claims 1 to 6, wherein the plurality of second submodules are electrically connected in parallel by a bus bar.   The solar cell module according to claim 7, wherein the bus bar is also present at both ends of the first solar cell panel. The plurality of first solar cells have a structure in which a first direction is a longitudinal direction,
The first sub-module is electrically connected in parallel in a second direction intersecting the first direction;
The first solar cells included in the first submodule are electrically connected in series in the second direction,
The plurality of second solar cells have a structure in which the first direction is a longitudinal direction,
The second submodule is electrically connected in parallel in the second direction;
The second solar cells included in the second submodule are electrically connected in series in the second direction,
The solar cell module according to claim 7 or 8, wherein the bus bar has the first direction as a longitudinal direction. A first solar panel in which a plurality of first submodules including a plurality of first solar cells are electrically connected by a bus bar;
A solar cell module having a second solar cell panel laminated with the first solar cell panel and in which a plurality of second submodules including a plurality of second solar cells are electrically connected by a bus bar. A photovoltaic power generation system using the solar cell module according to any one of claims 1 to 10.