Patent Application
20210376174
This application is based upon and claims the benefit of priority from Japanese Patent Applications No. 2016-184900, filed on Sept. 21, 2016, No. 2017-056694 filed on Mar. 22, 2017, and No. 2017-125122 filed on Jun. 27, 2017; the entire contents of which are incorporated herein by reference.
Embodiments described herein relate to a solar cell module and a photovoltaic power generation system.
As a high-efficiency solar cell, there is a multi-junction (tandem) solar cell. The multi-junction solar ceil is capable of using an efficient cell for each wavelength range, and therefore is expected to achieve a higher efficiency than a single-junction solar cell. Chalcopyrite solar cells, including CIGS solar cells, are known to be highly efficient, and can be a candidate for a top cell if they have a wide band gap. However, there has not fully been studied a method for connecting solar cells with different band gaps in a module in which the solar cells are joined.
A solar cell module of an embodiment includes: a first solar panel having a plurality of first submodules each including a plurality of first solar cells; and a second solar panel layered with the first solar panel, the second solar panel having a plurality of second solar cells. The first solar panel exists on the side where light is incident. The first solar panel and the second solar panel are electrically connected in parallel. The first solar cells included in the first submodules are electrically connected in series. The first submodules are electrically connected in parallel.
Embodiments are described in detail below with reference to drawings. Some of reference numerals of overlapping components in the drawings are omitted.
A solar cell module according to a first embodiment has a structure in which two or more solar panels are stacked on top of another. The two or more solar panels are electrically connected in parallel. As shewn in a perspective schematic diagram of
The first solar panel 10 is a panel existing on the top side of the solar cell module 100, i.e., the side where light is incident. The first solar panel 10 includes a plurality of solar cells with a wide-bandgap light-absorbing layer. The wide-bandgap light-absorbing layer includes, for example, at least one selected from the group consisting of the following: a compound semiconductor, a perovskite-type compound, a transparent oxide semiconductor, and amorphous silicon. The first solar panel 10 according to the first embodiment achieves excellent conversion efficiency by itself. Therefore, it is also preferable that the first solar panel 10 according to the first embodiment is used as stand-alone solar cells without being stacked on top of another solar panel. The first solar panel 10 includes a plurality of first submodules including a plurality of first solar cells.
The second solar panel 20 is a panel existing on the bottom side of the solar cell module 100, i.e., the side opposite to the light incident side. The second solar panel 20 includes a plurality of solar cells that generate electricity from transmitted light that has passed through the first solar panel 10. The second solar panel 20 includes a plurality of second submodules including a plurality of second solar cells.
Second solar cells of the second solar panel 20 have polycrystalline, monocrystalline Si, or a perovskite compound in their light-absorbing layer. The band gap of the polycrystalline, monocrystalline Si, or a perovskite compound light-absorbing layers is a narrower band gap than that of the light-absorbing layers of first solar cells.
The second solar panel 20 is, for example, a panel using any of the following types of solar cells: PERC (Passivated Emitter and Rear Contact cell) type, PERL (Passivated Emitter and Rear Locally diffusion cell) type and PERT (Passivated Emitter and Rear Totally diffusion cell) type, back contact type (Interdigitated Back Contact cell), and heterojunction (HIT) type.
Electricity generated by the first solar panel 10 and the second solar panel 20 is converted and then is stored, transmitted, or consumed. To store, transmit, or consume electricity, both electricity generated by the first solar panel 10 and electricity generated by the second solar panel 20 need to be converted by power conversion equipment (a converter). If separate converters are used to convert electricity in the first solar panel 10 and the second solar panel 20, two converters are required. An increase in the number of converters increases the power generation cost. Therefore, even though the number of stacked panels is two or more, the solar cell module 100 has a power output terminal (plus/minus)for only a single system because the panels are electrically connected in parallel. Even when the conversion efficiency is improved by using multi-junction solar cells, if the power generation cost increases, which is not preferable in terms of investment capital recovery despite the improvement in the conversion efficiency.
As shown in a schematic diagram of
The upper and lower electrodes of each first solar cell 11 of the first solar panel 10 need to be transparent electrodes. Transparent electrodes have a higher resistance than metal electrodes. If all the first solar cells 11 are connected in series in the second direction, the area of one cell increases, and the increase in resistance of the transparent electrodes decreases the conversion efficiency of the first solar panel 10. If the width of the first solar cells 11 in the second direction is adjusted in consideration of the resistance of the transparent electrodes, and all the first solar cells 11 are connected in series, the output voltage of the first solar panel 10 does riot match that of the second solar panel 20. Furthermore, for example, if the first solar panel 10 includes one solar cell, the difference in output voltage between the first solar panel 10 and the second solar panel 20 becomes larger.
Accordingly, preferably, the first solar panel 10 includes a plurality of first submodules 11A of the first solar cells 11 electrically connected in series in the second direction, and the plurality of first submodules 11A are electrically connected in parallel in the second direction. By adopting this configuration, the first solar panel 10 can match the output voltage with that of the second solar panel 20, while having a connection configuration of the first solar cells 11 having the high conversion efficiency. The difference in output voltage between the first solar panel 10 and the second solar panel 20 is preferably 2.0 V or less. Preferably, the smaller the difference in output voltage, the smaller the loss caused by the difference in output voltage. Therefore, the difference in output voltage between the first solar panel 10 and the second solar panel 20 is more preferably 1.5 V or less or 1.0 V or less, still more preferably 0.5 V or less. The number of the plurality of first submodules 11A in the first solar panel 10 is preferably two or more but not exceeding ten. If a parallel number is small, the transparent electrode area per first solar cell 11 is large, and the increase in resistance due to the transparent electrodes decreases the power generation efficiency. Furthermore, if a parallel number is too large, the number of the first solar cells 11 in the first solar panel 10 is large, and a non-power-generation region, such as a ring region, increases, and the power generation efficiency decreases.
Here, there is described an example of the solar cell module 100 in which the first solar panel 10 using CGSS (Cu0.95GaSe1.95S0.05) with an open circuit voltage Voc of 0.95 V in its light-absorbing layer and the second solar panel 20 using polycrystalline Si with Voc of 0.66 V in its light-absorbing layer are stacked.
The second solar panel 20 includes six arrays of second submodules 21A that are electrically connected in series; each of the second submodules 21A includes ten second solar cells 21 using Si in their light-absorbing layer that are electrically connected in series. The open circuit voltage Voc of these second solar cells 21 is 0.66 V. As 60 cells with Voc of 0.66 V are connected in series, the open circuit voltage Voc of the second solar panel 20 is 39.6 V (a stand-alone value, which decreases to 37.8 V after the top panel is put thereon). On the other hand, the open circuit voltage Voc of the first solar cells 11 using CGSS in their light-absorbing layer is 0.95 V. To match Voc of the first solar panel 10 with that of the second solar panel 20, i.e., Voc of 39.6 V, 41 arrays of first solar cells 11 are preferably connected in series. If 41 arrays of first solar cells 11 with Voc of 0.95 V are connected in series, Voc of the first solar cells 11 is 39.9 V. Such a panel is about 1 m long in both the first and second directions; for example, when the panel is divided into 41 parts in the second direction, the area of the first solar cells 11 is substantially large. Therefore, 41 arrays of first solar cells 11 connected in series are arranged in parallel. A parallel number is two or more but riot exceeding ten. In general, in view of Voc, FF, etc. of the bottom panel with the top panel put thereon, it should be set so that the difference in Voc at the maximal output is small.
A solar cell module according to a second embodiment has a structure in which two or more solar panels are stacked on top of another. The two or more solar panels are electrically connected in parallel. As shown in a perspective schematic diagram of
The busbars 12 are metallic plates that connect a plurality of first submodules 11A in the second direction.
In
In
In
In
In
As the substrate 13 in the second embodiment, it is preferable to use soda lime glass, or glass in general, such as quartz, super white glass, and chemically strengthened glass, and resin, such as polyimide and acrylic, can also be used.
The first electrode 14 in the second embodiment is an electrode of the first solar panel 10. The first electrode 14 is, for example, a transparent electrode containing a semiconductor film formed on the substrate 13. The first electrode 14 exists between the substrate 13 and the light-absorbing layer 15. The first electrode 14 can contain a thin film. As the first electrode 14, a semiconductor film containing at least ITO (Indium-Tin Oxide) can be used. On ITO on the side of the light-absorbing layer 15, a carrier-doped layer containing oxide, such as SnO2, TiO2, ZnO:Ga or ZnO:Al, can be lamdnated. ITO and SnO2 can be laminated from the side of the substrate 13 toward the side of the light-absorbing layer 15, or ITO, SnO2, and TiO2 can be laminated from the side of the substrate 13 toward the side of the light-absorbing layer 15. The layer in contact with a light-absorbing layer of the first electrode 14 is preferably any one of the following oxide layers: ITO, SnO2, and TiO2. Furthermore, a layer containing oxide, such as SiO2, can be further installed between the substrate 13 and ITO. The film of first electrode 14 can be formed on the substrate 13 by sputtering or the like. The film thickness of the first electrode 14 is, for example, 100 nm or more but not exceeding 1000 nm. In the case where the solar cells in the second embodiment are used in a multi-junction solar cell, it is preferable that the solar cells in the second embodiment exist the top cell side or the middle cell side, and the first electrodes 14 are transparent semiconductor films.
The light-absorbing layer 15 in the second embodiment is at least one type layer of a compound semiconductor, a perovskite-type compound, a transparent oxide semiconductor, and amorphous silicon. The light-absorbing layer 15 is a layer forming a p-n junction with the buffer layer 16. If the light-absorbing layer 15 is p-type, the buffer layer 16 is n-type; if the light-absorbing layer 15 is n-type, the buffer layer 16 is p-type. The light-absorbing layer 15 exists between the first electrodes 14 and the buffer layer 16. If the light-absorbing layer 15 is homojunction type, the buffer layer 16 can be omitted.
The light-absorbing layer 15 can use, as a light-absorbing layer, a compound semiconductor layer having a chalcopyrite structure, such as Cu(In,Ga)Se2, CuInTe2, CuGaSe2, Cu(In,Al)Se2,Cu(Al,Ga) (S,Se)2, or CuGa(S,Se)2,Ag (In,Ga)Se2, Cu(In,Ga) (S,Se)2, or a compound semiconductor layer, such as CdTe, (Cd,Zn,Mg) (Te,Se,S), or (In,Ga)2(S,Se,Te)3. Furthermore, the light-absorbing layer 15 can also use a compound semiconductor layer having a kesterite structure or stannite structure represented by CZTS (Cu2ZnSnS4) or a CdTe layer. The film thickness of the light-absorbing layer 15 is, for example, 800 nm or more but not exceeding 3000 nm.
A transparent oxide semiconductor, such as Cu2O can be used as the light-absorbing layer 15.
A combination of elements helps to adjust the band gap to an intended value. The intended value of the band gap is, for example, 1.0 eV or more but not exceeding 2.7 eV.
The light absorbing layer 15 provided on the side of a top cell and having a large band gap is preferable because power generation in the second solar cell at the bottom side increases due to have wider band gap in the light absorbing layer 15 provided on the side of a top cell. The light absorbing layer 15 having more wider band gap, such as Cu2O, (Cd, Zn, Mg) (Te, Se, S) or (In, Ga)2 (S, Se, Te)3 can be preferably used.
Besides the above, the light-absorbing layer 15 can use a Perovskite type compound or amorphous silicon layer represented by CH3NH3PbX3 (X is at least one or more types of halogen).
The buffer layer 16 in the second embodiment is an n-type or p-type semiconductor layer. The buffer layer 16 exists between the light-absorbing layer 15 and the second electrode 17. The buffer layer 16 is a layer in direct contact with the surface of the light-absorbing layer 15 on the opposite side of the surface facing toward the first electrode 14. Then, the buffer layer 16 is a layer forming a heterojunction with light-absorbing layer 15. The buffer layer 16 is preferably an n-type or p-type semiconductor of which the Fermi level is controlled so as to obtain a solar cell with a high open circuit voltage.
In the case where the light-absorbing layer 15 is a chalcopyrite-type compound, a kesterite-type compound, or a stannite-type compound, the buffer layer 16 can use, for example, Zn1-yMyO1-xSx, Zn1-y-zMgzMyO, ZnO1-xSx, Zn1-zmgzO (M is at least one element selected from a group of B, Al, In, and Ga) CdS, etc. The thickness of the buffer layer 16 is preferably 2 nm or more but not exceeding 800 nm. The film of buffer layer 16 is formed, for example, by sputtering or chemical bath deposition (CBD). When the film of buffer layer 16 is formed by CBD, the buffer layer 16 can be formed on the light-absorbing layer 15, for example, by a chemical reaction of metal salt (for example, CdSO4) and sulfide (thiourea) with complexing agent (ammonia) in aqueous solution. In the case where a chalcopyrite-type compound not containing In in IIIb group elements, such as a CuGaSe2 layer, a AgGaSe2 layer, a CuGaAlSe2 layer, and a CuGa (Se, S)2 layer is used in the light-absorbing layer 15, CdS is preferable as the buffer layer 16.
In the case where the light-absorbing layer 15 is CdTe, n-type CdS is preferable as the buffer layer 16.
In the case where the light-absorbing layer 15 is a perovskite-type compound, the buffer layer 16 is a so-called n-type compact layer. As the compact layer, one or more layers of oxides selected from the group consisting of titanium oxide, zinc oxide, allium oxide, and the like are preferable.
In the case where the light-absorbing layer 15 is amorphous silicon, the buffer layer 16 is preferably a-SiC:H because it has a wide band gap and is easy-to-form in a process.
The oxide layer in the second embodiment is a thin film that is preferably installed between the buffer layer 16 and the second electrode 17. The oxide layer is a thin film containing any of the following compounds: Zn1-xMgxO, ZnO1-ySy, and Zn1-xmgxO1-ySy (0≤x, y<1). The oxide layer can be configured not to cover the whole surface the buffer layer 16 facing toward the second electrode 17. For example, the oxide layer only has to cover 50% of the surface of the buffer layer 16 on the side of the second electrode 17. Other candidates include AlOz, SiOz, SiNz, and wurtzite-type such as AlN, GaN, and BeO. If the volume resistivity of the oxide layer is 1 Ωcm or more, there is an advantage that it is possible to suppress leakage current deriving from a low-resistance component that is likely to exist in the light-absorbing layer 15. Incidentally, in the second embodiment, the oxide layer can be omitted. The oxide layer is an oxide particle layer, and preferably has many voids therein. The intermediate layer is not limited to the above-mentioned compounds and physical property, and only has to be a layer contributing to the improvement in the conversion efficiency of the solar cell. The intermediate layer can be multiple layers with different physical properties.
The second electrode 17 second embodiment is an electrode film that transmits light such as sunlight therethrough and has conductivity. The second electrode 17 is in direct contact with the surface of an intermediate layer or the buffer layer 16 on the opposite side of the surface facing toward the light-absorbing layer 15. The joined light-absorbing layer 15 and buffer layer 16 exist between the second electrode 17 and the first electrode 14. The film of second electrode 17 is formed, for example, by sputtering in the Ar atmosphere. The film of second electrode 17 can use, for example, ZnO:Al using a ZnO target containing 2 wt % alumina (Al2O3) ZnO:B with B dopant from diborane triethylboron.
A third electrode in the second embodiment is an electrode of the first solar cell 11, and is a metal film formed on the second electrode 17 on the opposite side of the side of the light-absorbing layer 15. As the third electrode, a conductive metal film, such as Ni and Al, can be used. The film thickness of the third electrode is, for example, 200 nm or more but not exceeding 2000 nm. Furthermore, in the case where the resistance value of the second electrode 17 is low, and a series resistance component is negligible, the third electrode can be omitted.
Antireflection coating in the second embodiment is a film for making it easy to introduce light into the light-absorbing layer 15, and is formed on the second electrode 17 or on the third electrode on the opposite side of the side of the light-absorbing layer 15. As the antireflection coating, for example, it is preferable to use MgF1 or SiO2. Incidentally, in the second embodiment, the antireflection coating can be omitted. The film thickness of each layer needs to be adjusted according to its refractive index; however, it is preferable to evaporate the film to be 70 to 130 nm (more preferably, 80 to 120 nm) thick.
A method for manufacturing the first solar cells 11 and the sections P1, P2, and P3 in patterns 1, 2, and 3 are briefly described. The first electrode 14 is formed on the substrate 13, and is subjected to scribing, and the section P1 is formed. Then, films of the light-absorbing layer 15 and the buffer layer 16 are formed. The light-absorbing layer 15 is formed on the section P1 as well. The light-absorbing layer 15 and the buffer layer 16 are subjected to scribing, and the section P2 is formed. Then, the second electrode 17 is formed on the buffer layer 16. The second electrode 17 is formed on the section P2 as well. Then, the light-absorbing layer 15, the buffer layer 16, and the second electrode 17 are subjected to scribing, and the section P3 is formed. Then, series-connected first solar cells 11 are obtained. The busbars 12 can be formed on the substrate before the film of first electrode 14 is formed, or can be formed after the scribing process for the formation of the section P3.
The first electrode 14 and the second electrode 17 are both a transparent electrode that transmits light therethrough, so tend to have a higher resistance than a metal electrode. Therefore, if the areas of the first electrode 14 and the second electrode 17 are large, the effect of the high resistance of the electrodes becomes prominent. The size of even a small solar panel is about 1200 mm×600 mm, and the size of a large solar panel is about 16000 mm×1000 mm. The area of the solar panel 10 is large, so that just connecting the first solar cells 11 in series results in the large areas of the first electrode 14 and the second electrode 17 per first solar cell 11 as well. In the second embodiment, the first submodules 11A are electrically connected in parallel; therefore, the area of a transparent electrode per cell or the width of one cell (the width of a transparent electrode) can be reduced. The area of a transparent electrode is reduced to be small, which increases the number of parallel connections, and increases a non-power-generation region. Therefore, reducing the area of a transparent electrode to be too small is not preferable. Furthermore, electricity generated by the cells flows in the width direction (short direction) that is the second direction. Therefore, by lessening the distance between transparent electrodes in the width direction, the effect of the resistance of the transparent electrodes can be softened. From these facts, the width of the first electrode 14, the width of the second. electrode 17, or the widths of the first electrode 14 and the second electrode 17 are preferably 3 mm or more hut not exceeding 15 mm, more preferably 3.3 mm or more but not exceeding 8 mm, still more preferably 3.5 mm or more but not exceeding 8 mm. Incidentally, the width of the first electrode 14 is the second-direction length of the first electrode 14 facing the substrate 13. Likewise, the width of the second electrode 17 is the second-direction length of the second electrode 17 facing the substrate 13.
A solar cell module according to a third embodiment has a structure in which two or more solar panels are stacked on top of another. The two or more solar panels are electrically connected in parallel. As shown in a perspective schematic diagram of
If the busbar 12 of the first solar panel 10 overlaps with the second solar cell 21, the amount of light, that, the second solar cell 21 receives is reduced. If the busbar 12 between first submodules 11A exists on a non-power-generation region that is a region between a plurality of second submodules 21A of the second solar cells 21, the effect on the light receiving amount of the second solar cells 21 is less, which is preferable. The second solar cells 21 are all electrically connected in series. Therefore, when the light receiving amount of one cell is reduced due to a busbar 12, the overall output voltage decreases, which is not preferable.
When respective polarities of the first submodules 11A of the first solar panel 10 alternate positive and negative, it is preferable that the number of busbars 12 is (n/m)+1, where n denotes the number of arrays of the plurality of second submodules 21A of the second solar cells 21 and m denotes a divisor of n, and the busbars 12 are arranged at equally spaced intervals. Of the busbars 12, two exist at both ends of the first solar panel 10 in the second direction. It is preferable that, as shown in a cross-sectional schematic diagram of the solar cell module in
When a busbar 12 exists on the non-power-generation region of the second solar panel 20, it is preferable that the overlapping distance between the busbar 12 on the non-power-generation region of the second solar panel 20 when projected onto the side of the second solar panel 20 in the third direction and the second solar cells 21 is small. An overlapping distance O1 between the busbar 12 and the second solar cell 21 is +X mm in.
A solar cell module according to a fourth embodiment includes a first solar panel and a second solar panel stacked together with the first solar panel; the first solar panel includes a plurality of first submodules that are electrically connected by busbars and each include a plurality of first solar cells. It is preferable that the two solar panels are electrically connected in parallel.
In the first solar panel 10 shown in
In the second solar panel 20 shown in
The busbars 12 of the first solar panel 10 exist on a non-power-generation region of the second solar panel 20 where no second solar cells 21 are installed. Even if the submodules are not uniform in size and direction and the busbars 12 are not uniform in direction, the busbars 12 are less likely to be shielded by the second solar cells 21. The first solar panel 10 can be configured so as to increase the amount of light reaching a power-generation region of the second solar panel 20. Also in this configuration, the power generation voltage of the first solar panel 10 can be matched with that of the second solar panel 20, and the first solar panel 10 and the second solar panel 20 can be connected in parallel so as to keep loss low.
A solar cell module according to a fifth embodiment includes a first solar panel and a second solar panel stacked together with the first solar panel; the first solar panel includes a plurality of first submodules that are electrically connected by busbars and each include a plurality of first solar cells. The solar cell module according to the fifth embodiment is a variation of the solar cell module according to the fourth embodiment. It is preferable that the two solar panels are electrically connected in parallel.
The solar cell module according to the fifth embodiment is the same as the solar cell module according to the fourth embodiment, except that they differ in the shape of the panels and the arrangement or configuration of the submodules.
In the case where the panel shape is polygonal, if the submodules are arranged in the same manner as the fourth embodiment, some of the submodules protrude from the panels, so the arrangement and configuration of the submodules are altered as shown in the schematic diagrams of
In the first solar panel 10 shown in the schematic diagram of
In the second solar panel 70 shown in the schematic diagram of
When the solar panels shown in
The solar cell modules 100, 101, and 102 according to the first to third embodiments and the solar cell modules according to the fourth and fifth embodiments can be used as a power generator that generates electricity in a photovoltaic power generation system according to a sixth embodiment. The photovoltaic power generation system according to the present embodiment is for generating electricity by using a solar cell module, and, specifically, includes a solar cell module configured to generate electricity, a unit configured to convert generated electricity, and an electricity storage unit configured to store the generated electricity or a load configured to consume the generated electricity.
Solar cells included in the solar cell module 201 having received light generate electricity, and its electric energy is converted by the converter 202 and then is stored in the storage battery 203 or consumed by the load 204. Preferably, the solar cell module 201 is installed with a solar-light tracking/drive device configured to constantly turn the solar cell module 201 to face to the sun, or is provided with a light collector configured to collect solar light, or added with a device or the like for improving the power generation efficiency.
Preferably, the photovoltaic power generation system 200 is used in immovables, such as houses, commercial facilities, and factories, or is used in movables, such as vehicles, aircrafts, and electronic devices. By using a photoelectric converter with excellent conversion efficiency in the solar cell module 201 in the present embodiment, the amount of generated electricity is expected to increase.
The present embodiments are specifically explained below on the basis of examples; however, the present embodiments are not limited to the following examples.
In Example 1, Cu0.95GaSe1.95S0.05 is used in light-absorbing layers of first solar cells of a first solar panel, and polycrystalline Si is used in light-absorbing layers of second solar cells of a second solar panel. The first solar panel and the second solar panel have the same size of 1650 mm in the first direction × 991 mm in the second direction. The first solar cells all have the same width of 3.94 mm (the width of second electrodes of the cells is also the same), and are arranged in 246 arrays in the second direction. The 41 cells are electrically connected in series, and six first submodules 11A are formed. A total of seven 3-mm busbars are installed at both ends and in between the six first submodules 11A, and are electrically connected in parallel. The busbars are arranged at the positions not overlapping with the second solar cells. Six arrays of second submodules 21A of ten second solar cells, which are arranged in the first direction in each array and are connected in series, are arranged in the second direction. The six series second submodules 21A are also connected in series, and the 60 second solar cells are connected in series.
First, with respect to each of the first solar panel and the second solar panel, Jsc, Voc, and the conversion efficiency are found; then, the conversion efficiency of a solar cell module in which the first solar panel and the second solar panel are stacked on top of another and electrically connected in parallel is found. Table 1 shows the results together with results of other examples and comparative examples.
Example 2 is The same as Example 1, except that the busbars of the first solar panel and the first solar cells are arranged so that all the busbars overlap by 1 mm with the second solar cells.
Example 3 is the same as Example 1, except that the busbars 2.0 of the first solar panel and the first solar cells are arranged so that all the busbars overlap by 2 mm with the second solar cells.
The first solar cells all had the same width of 4.74 mm (the width of the second electrodes of the cells is also the same), and are arranged in 205 arrays in the second direction. The 41 cells are electrically connected in series, and five first submodules 11A are formed. A total of six 3-mm busbars are installed at both ends and in between the five first submodules 11A. Then, Example 4 is the same as Example 1, except that the busbars of the first solar panel and the first solar cells are arranged so that the busbars overlap by 2 mm or less with the second solar cells.
The first solar cells all had the same width of 7.95 mm (the width of the second electrodes of the cells is also the same), and are arranged in 123 arrays in the second direction. The 41 cells are electrically connected in series, and three first submodules 11A are formed. Example 5 is the same as Example 1, except that a total of four busbars are installed at both ends and in between the three first submodules 11A, and the busbars of the first solar panel and the first solar cells are arranged.
The first solar cells all have the same width of 11.96 mm (the width of the second electrodes of the cells is also the same), and are arranged in 82 arrays in the second direction. The 41 cells are electrically connected in series, and two first submodules 11A are formed. Example 6 is the same as Example 1, except that a total of three busbars are installed at both ends and in between the two first submodules 11A, and the busbars of the first solar panel and the first solar cells are arranged.
The first solar cells all have the same width of 3.73 mm (the width of the second electrodes of the cells is also the same), and are arranged in 240 arrays in the second direction. The 40 cells are electrically connected in series, and six first submodules 11A are formed. Example 7 is the same as Example 1, except that a total of five busbars are installed at both ends and in between the six first submodules 11A, and the busbars of the first solar panel and the first solar cells are arranged.
The first solar cells are one array of stand-alone cells with a width of 985 mm (the width of the second electrodes of the cells is also the same). Compare Example 1 is the same as Example 1, except that a total of two busbars are installed at both ends of the first solar panel, and the busbars of the first solar panel and the first solar cells are arranged.
The first solar cells all have the same width of 24 mm (the width of the second electrodes of the cells is also the same), and are arranged in 41 arrays in the second direction. The 41 cells are electrically connected in series, and one first submodules 11A is formed. Comparative Example 2 is the same as Example 1, except that a total of two busbars are installed at both ends of the first solar panel, and the busbars of the first solar panel and the first solar cells are arranged.
Cu0.93GaSe2 is used in the light absorbing layers of the first solar is of the first solar panel. The first solar cells all have the same width of 3.75 mm (the width of the second electrodes of the cells is also the same), and are arranged in 258 arrays in the second direction. The 43 cells are electrically connected in series, and six first submodules 11A are formed. A total of seven 3-mm busbars are installed at both ends and in between the six first submodules 11A, and are electrically connected in parallel. The busbars are arranged at the positions not overlapping with the second solar cells. Except for these, Example 8 is the same as Example 1.
A perovskite compound is used in the light-absorbing layers of the first solar cells of the first solar panel. The first solar cells all have the same width of 4.36 mm (the width of the second electrodes of the cells is also the same), and are arranged in 222 arrays in The second direction. The 37 cells are electrically connected in series, and six first submodules 11A are formed. A total of seven 3-mm busbars are installed at both ends and in between the six first submodules 11A, and are electrical y connected in parallel. The busbars are arranged at the positions not overlapping with the second solar cells. Except for these, Example 9 is the same as Example 1.
Amorphous silicon is used in the light-absorbing layers of the first solar cells of the first solar panel. The first solar cells all have the same width of 3.83 mm (the width of The second electrodes of the cells is also the same), and are arranged in 252 arrays in The second direction. The 42 cells are electrically connected in series, and six first submodules 11A are formed. A total of seven 3-mm busbars are installed at both ends and in between the six first submodules 11A, and are electrically connected in parallel. The busbars are arranged at the positions not overlapping with the second solar cells. Except for these, Example 10 is the same as Example 1.
A CdTe compound is used in the light-absorbing layers of the first solar cells of the first solar panel. The first solar cells all have the same width of 3.5 mm (the width of the second electrodes of the cells is also the same), and are arranged in 276 arrays in the second direction. The 46 cells are electrically connected in series, and six first submodules 11A are formed. A total of seven 3-mm busbars are installed at both ends and in between the six first submodules 11A, and are electrically connected in parallel. The busbars are arranged at the positions not overlapping with the second solar cells. Except for these, Example 11 is the same as Example 1.
From these examples, it turns out that a panel with an efficiency exceeding that of Si alone can be obtained (even at present). The efficiency of the CGSS or CGS cells has room for improvement. If the efficiency is improved, the open circuit voltage is also improved, so that it will require consideration again, including the number of series connections. Furthermore, the efficiency of the bottom Si solar cell also improves day by day; therefore, a high-efficiency module can be obtained by stacking high-efficiency panels on top of another.
A difference between a band gap of the light absorbing layer of the first solar cell and a band gap of the light absorbing layer of the second solar cell can be increased by using Cu2O, (Cd, Zn, Mg) (Te, Se, S), (In, Ga)2 (S, Se, Te)3, having very wider band gap, as a light absorbing layer of the first solar cell. When the difference between the band gap of the light absorbing layer of the first solar cell and a band gap of the light absorbing layer of the second solar cell increases, the power generation increases because light that contributes to the power generation in the light absorbing layer of the second solar cell increases. By applying such multi-junction solar cell having large difference between the band gaps and also applying the connecting mode of the solar cells, the power generation in the second solar panel on the bottom side, increasing the power generation in the multi-junction solar cell is expected.
Here, some elements are expressed only by element symbols thereof.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-184900 | Sep 2016 | JP | national |
| 2017-056694 | Mar 2017 | JP | national |
| 2017-125122 | Jun 2017 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15698392 | Sep 2017 | US |
| Child | 17404409 | US |
