A solar cell, a cell assembly, and a photovoltaic system

Abstract

The application provides a solar cell, a cell assembly and a photovoltaic system. The solar cell comprises a substrate, a first surface of the substrate is provided with a plurality of collecting grid lines, the plurality of collecting grid lines are arranged at intervals along a first direction, each collecting grid line comprises a plurality of grid line segments arranged along a second direction, the first direction and the second direction intersect each other, a solder pad is arranged between two adjacent grid line segments, the solder pad is in contact with the two adjacent grid line segments, the solder pad comprises a plurality of wire segments, the plurality of wire segments are arranged in sequence along the first direction, or the plurality of wire segments are arranged in sequence along the second direction, or the plurality of wire segments are arranged around a preset point of the solder pad. The application can reduce the cost of the solar cell.

Description

Technical Field

[0001] This application relates to the field of photovoltaic technology, and in particular to a solar cell, a battery module and a photovoltaic system. Background Technology

[0002] Solar cells, as a highly efficient and clean energy conversion device, are widely used in various photovoltaic power generation systems. A solar cell consists of a substrate and grid lines disposed on the substrate. The grid lines and the silicon substrate are in ohmic contact, responsible for effectively collecting electrons and holes (charge carriers) generated by the substrate under sunlight, and then converting them into usable electrical energy.

[0003] As technology advances, there is a desire to further reduce the cost of solar cells. However, existing solar cells are relatively expensive. Utility Model Content

[0004] This application provides a solar cell, a battery module, and a photovoltaic system that can reduce costs.

[0005] According to one aspect of this application, a solar cell is provided, comprising:

[0006] A substrate, wherein a plurality of collection grid lines are disposed on a first surface of the substrate, the plurality of collection grid lines being spaced apart along a first direction; each collection grid line includes a plurality of grid line segments disposed along a second direction; wherein the first direction and the second direction intersect each other.

[0007] A pad is provided between two adjacent gate line segments, and the pad is in contact with the two adjacent gate line segments; the pad includes multiple conductive segments; the multiple conductive segments are arranged sequentially along a first direction, or the multiple conductive segments are arranged sequentially along a second direction, or the multiple conductive segments are arranged around a preset point of the pad.

[0008] Optionally, when multiple conductor segments are set to wrap around preset points on the pad:

[0009] The first ends of the plurality of conductor segments of the pad are connected to each other, or the pad may further include a first central portion, with the plurality of conductor segments arranged around the first central portion and the first ends of the plurality of conductor segments electrically connected to the first central portion.

[0010] Optionally, the first central part can be circular, elliptical, semi-circular, semi-elliptical, fan-shaped, or polygonal.

[0011] The first central portion has a dimension of 400 micrometers to 550 micrometers along the first direction, and the first central portion has a dimension of 400 micrometers to 550 micrometers along the second direction.

[0012] Optionally, when multiple conductor segments are arranged sequentially along the first direction:

[0013] The pad further includes a second central portion, the width of which along the first direction is greater than the width of which the conductor segment along the first direction; a plurality of conductor segments are respectively disposed on both sides of the second central portion along the first direction, and the gate segment is connected to the second central portion.

[0014] Optionally, the second central portion is a polygon;

[0015] The second central portion has a dimension of 400-550 micrometers along the first direction, and the second central portion has a dimension of 800-1100 micrometers along the second direction.

[0016] Optionally, when multiple conductive segments are arranged sequentially along the second direction:

[0017] The pad also includes a connecting portion, which connects to a plurality of the conductor segments, and the gate line segment is connected to any of the conductive segments.

[0018] Optionally, a plurality of the conductor segments are located on one or both sides of the connector along the second direction, and the grid line segments are connected to the connector;

[0019] The dimension of the connecting part along the first direction is 400 micrometers-550 micrometers, and the dimension of the connecting part along the second direction is 800 micrometers-1100 micrometers.

[0020] Optionally, the linewidth of the conductor segment is 100 micrometers to 400 micrometers;

[0021] The pad has a size of 800-1100 micrometers along the first direction and a size of 800-1100 micrometers along the second direction.

[0022] According to another aspect of this application, a battery assembly is provided, including the solar cell described in any embodiment of this application.

[0023] According to another aspect of this application, a photovoltaic system is provided, including the battery module described in any embodiment of this application.

[0024] This application embodiment sets the pad to include multiple conductive segments; the multiple conductive segments are arranged sequentially along a first direction, or the multiple conductive segments are arranged sequentially along a second direction, or the multiple conductive segments are set around a preset point of the pad. Since the amount of paste used by the multiple conductive segments is less than the amount of paste used by the solid block pad, the paste consumption of the solar cell can be reduced. In addition, the setting of multiple conductive segments can ensure a better connection between the pad and the solder strip, thus ensuring the reliability of the solar cell module.

[0025] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of a solar cell provided in an embodiment of this application.

[0028] Figure 2 This is a schematic diagram of a solder pad provided in an embodiment of this application.

[0029] Figure 3 This is a schematic diagram of another type of solder pad provided in the embodiments of this application.

[0030] Figure 4 This is a schematic diagram of another type of solder pad provided in the embodiments of this application.

[0031] Figure 5 This is a schematic diagram of another type of solder pad provided in the embodiments of this application.

[0032] Figure 6 This is a schematic diagram of another type of solder pad provided in the embodiments of this application.

[0033] Figure 7 This is a schematic diagram of another type of solder pad provided in the embodiments of this application.

[0034] Reference numerals: 10-substrate, 20-collection grid line, 201-first collection grid line, 202-second collection grid line, 21-grid line segment, 30-pad, 31-conductor segment, 32-first center portion, 33-second center portion, 34-connector portion, 60-solder strip. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0036] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0037] This application provides a solar cell, Figure 1 This is a schematic diagram of a solar cell provided in an embodiment of this application. Figure 2 This is a schematic diagram of a solder pad provided in an embodiment of this application. Figure 3 This is a schematic diagram of another type of solder pad provided in an embodiment of this application. Figure 4 This is a schematic diagram of another type of solder pad provided in an embodiment of this application. Figure 5 This is a schematic diagram of another type of solder pad provided in an embodiment of this application. Figure 6 This is a schematic diagram of another type of solder pad provided in an embodiment of this application. Figure 7 This is a schematic diagram of yet another type of solder pad provided in an embodiment of this application. (Reference) Figures 1-7 The solar cells include:

[0038] The substrate 10 has a plurality of collection grid lines 20 disposed on its first surface. The plurality of collection grid lines 20 are arranged at intervals along a first direction X. Each collection grid line 20 includes a plurality of grid line segments 21 disposed along a second direction Y. The first direction X and the second direction Y intersect each other.

[0039] A pad 30 is provided between two adjacent gate line segments 21, and the pad 20 contacts the two adjacent gate line segments 21; the pad 30 includes multiple conductor segments 31; the multiple conductor segments 31 are arranged sequentially along the first direction X, or the multiple conductor segments 31 are arranged sequentially along the second direction Y, or the multiple conductor segments 31 are arranged around a preset point of the pad 30.

[0040] The substrate 10 is the foundation of the solar cell. The substrate 10 may include a silicon substrate and various functional layers stacked on the silicon substrate; that is, the substrate 10 is the part of the solar cell excluding the metallized electrode pattern. The functional layers include a first doped layer and a second doped layer. In addition, the functional layers may also include tunneling layers, passivation layers, antireflection layers, etc. The first and second doped layers have different doping types; for example, the first doped layer can be an n-type doped layer, and the second doped layer can be a p-type doped layer. The silicon substrate can be an n-type silicon substrate or a p-type silicon substrate. The silicon substrate and the p-type or n-type doped layer form a pn junction, generating a photovoltaic effect. When light shines on the solar cell, photons can excite electrons to jump from the valence band to the conduction band, forming electron-hole pairs. These charge carriers separate at the pn junction due to the built-in electric field, generating a current. The substrate 10 has opposing light-facing and back-light-receiving surfaces. The light-facing surface of the substrate 10 is the light-receiving surface of the substrate 10, and the first surface of the substrate 10 can be the back-light-receiving surface of the substrate 10.

[0041] A collection gate line 20 is disposed on the substrate 10, and the collection gate line 20 is used to collect carriers generated by the substrate 10. For example, the collection gate line 20 may include a first collection gate line 201 and a second collection gate line 202. The first collection gate line 201 is disposed in the region of the first doped layer on the substrate 10, and the first collection gate line 201 is in contact with the first doped layer. The first collection gate line 201 is used to collect carriers from the first doped layer. The second collection gate line 202 is disposed in the region of the second doped layer on the substrate 10, and the second collection gate line 202 is in contact with the second doped layer. The second collection gate line 202 is used to collect carriers from the second doped layer. The collecting gate line 20 includes multiple gate line segments 21 arranged along the second direction Y. Pads 30 are electrically connected to the gate line segments 21. Specifically, the first collecting gate line 201 includes multiple gate line segments 21, and the gate line segments 21 of the first collecting gate line 201 are connected to the corresponding pads 30. The second collecting gate line 201 also includes multiple gate line segments 21, and the gate line segments 21 of the second collecting gate line 202 are connected to the corresponding pads 30. The pads 30 are used for electrical connection with the solder ribbon 60, allowing the solder ribbon 60 to draw out the charge carriers from the collecting gate line 42.

[0042] In the fabrication of solar cells, the n-type silicon wafer is typically polished using wet etching to remove the surface mechanical damage layer. SiO2 and polycrystalline silicon are then fabricated on the back side of the wafer using a thin-film deposition (LP) system. The polycrystalline silicon is then boron-diflated using a diffusion system to create the first doped layer. The first doped layer is patterned using laser engraving. Residue from the laser-engraved areas is removed by wet cleaning, and the laser-engraved areas are then textured. SiO2 and polycrystalline silicon are then fabricated using an LP system, and the polycrystalline silicon is phosphorus-diflated using a diffusion system to activate passivation, creating the second doped layer. The second doped layer is patterned using laser engraving. Wet etching is then used to remove the polycrystalline silicon layer and oxide layer from the front side of the wafer. Wet etching is then used to texturize the front side. Medium-temperature surface coating is then applied to both the front and back surfaces. The collection grid lines 20 are then metallized. The collection grid lines 20 can be fabricated using processes such as printing.

[0043] In existing solar cells, the pads 30 are typically solid blocks, resulting in significant paste consumption during fabrication. This embodiment reduces paste consumption by including multiple conductive segments 31 within the pads 30. (Reference) Figures 2-4 The pad 30 can be snowflake-shaped, with multiple conductor segments 31 arranged around a preset point on the pad 30. The preset point can be the center point. One end of each conductor segment 31 is electrically connected, and the other end is radiating outwards. The gate line segment 21 can be electrically connected to any conductor segment 31 or to the center of the pad 30. (Reference) Figure 5 Multiple conductor segments 31 can also be arranged sequentially along the first direction X, and the grid line segment 21 can be electrically connected to any conductor segment 31. (Reference) Figure 6 and Figure 7 Multiple conductor segments 31 can also be arranged sequentially along the second direction Y, and the grid end 21 can be electrically connected to any conductor segment 31.

[0044] In this embodiment, the pad 30 is configured to include multiple conductive segments 31. The multiple conductive segments 31 are arranged sequentially along the first direction X, or sequentially along the second direction Y, or the multiple conductive segments 31 are arranged around a preset point of the pad 30. Since the amount of paste used by the multiple conductive segments 31 is less than that used by the solid block pad 30, the paste consumption of the solar cell can be reduced. Furthermore, the arrangement of the multiple conductive segments 31 can ensure a better connection between the pad 30 and the solder ribbon 60, thus ensuring the reliability of the solar cell module.

[0045] Based on the above embodiments, optionally, refer to Figures 1-4 When multiple conductor segments 31 are set to surround the preset points of pad 30:

[0046] The first ends of the multiple conductor segments 31 of the pad 30 are interconnected. Figure 2Alternatively, the pad 30 may also include a first center portion 32, with a plurality of conductor segments 31 arranged around the first center portion 32, and the first ends of the plurality of conductor segments 31 electrically connected to the first center portion 32. Figure 3 and Figure 4 ).

[0047] For details, please refer to Figure 2 The first ends of multiple conductor segments 31 converge at a predetermined point and are interconnected at that point. (Reference) Figure 3 and Figure 4 The first central portion 32 is located at the center of the pad 30, and the second ends of the plurality of conductor segments 31 are divergent. The gate segment 21 can contact any conductor segment 31 or the first central portion 32.

[0048] By setting the first ends of multiple wire segments 31 to be interconnected, that is, all wire segments 31 are interconnected, even if the position of the solder strip is offset when setting the solder strip, as long as the solder strip is connected to a wire segment 31, it can be electrically connected to the solder pad 30, thereby improving the reliability of the battery module.

[0049] By setting the pad 30 to include a first central portion 32, the pad 30 and the solder strip have a larger contact area, which can reduce contact resistance, reduce current transmission loss, and improve the photoelectric conversion efficiency of the solar cell.

[0050] Based on the above embodiments, optionally, the first central portion 32 can be circular, elliptical, semi-circular, semi-elliptical, fan-shaped, or polygonal.

[0051] Specifically, circular, elliptical, semi-circular, semi-elliptical, fan-shaped, and polygonal shapes are simple to manufacture, which can reduce the difficulty of manufacturing solar cells.

[0052] Based on the above embodiments, optionally, the size of the first central portion 32 along the first direction X is 400 micrometers-550 micrometers, and the size of the first central portion 32 along the second direction Y is 400 micrometers-550 micrometers.

[0053] This configuration ensures that the first central portion 32 has a large area, reduces the contact resistance with the solder ribbon, and ensures that the amount of solder paste consumed by the solder pad 30 is small.

[0054] Based on the above embodiments, optionally, refer to Figure 5 When multiple conductor segments 31 are arranged sequentially along the first direction X:

[0055] The pad 30 also includes a second center portion 33, the width of the second center portion 33 along the first direction X is greater than the width of the conductor segment 31 along the first direction X; a plurality of conductor segments 31 are respectively disposed on both sides of the second center portion 33 along the first direction X, and the gate line segment 21 is connected to the second center portion 33.

[0056] Specifically, by setting a wider second central portion 33, the pads 30 and the solder strip have a larger contact area, which reduces contact resistance, current transmission loss, and improves the photoelectric conversion efficiency of the solar cell. Furthermore, the grid line segment 21 is connected to the second central portion 33. Because the second central portion 33 has a larger width along the first direction X, it can connect to each other even if there are manufacturing position deviations in the first direction X, reducing the difficulty of the manufacturing process.

[0057] Optionally, based on the above embodiments, the second central portion 33 may be a polygon.

[0058] For example, the second central portion 33 can be a rectangle, parallelogram, pentagon, etc. Polygons are easy to manufacture. By setting the second central portion 33 to be a polygon, the manufacturing process of the pad 30 can be simplified, thereby reducing the manufacturing difficulty of the solar cell.

[0059] Based on the above embodiments, optionally, the size of the second central portion 33 along the first direction X is 400 micrometers-550 micrometers, and the size of the second central portion 33 along the second direction Y is 800 micrometers-1100 micrometers.

[0060] This configuration ensures that the second central part 33 has a large area, reduces the contact resistance with the solder strip, and ensures that the amount of paste consumed by the solder pad 30 is small.

[0061] Based on the above embodiments, optionally, refer to Figure 6 and Figure 7 When multiple conductive segments 31 are arranged sequentially along the second direction Y:

[0062] The pad 30 also includes a connecting portion 34, which connects multiple conductor segments 31, and the gate segment 21 is connected to any conductive segment 31.

[0063] Specifically, by setting the connecting part 34 to connect multiple wire segments 31, the wire segments 31 are electrically connected to each other, so that after the grid line segment 21 is connected to any wire segment 31, it can be connected to the solder strip. Moreover, after the position of the solder strip is shifted, as long as it is connected to one wire segment 31, it can be connected to the solder pad 30 and the grid line segment 21, thereby improving the reliability of the solar cell module.

[0064] Based on the above embodiments, optionally, refer to Figure 6 Multiple conductor segments 31 are located on one or both sides of the connecting part 34 along the second direction Y, and the grid line segment 21 is connected to the connecting part 34.

[0065] Based on the above embodiments, optionally, the dimension of the connecting portion 34 along the first direction X is 400 micrometers-550 micrometers, and the dimension of the connecting portion 34 along the second direction Y is 800 micrometers-1100 micrometers.

[0066] This configuration ensures that the connection part 34 has a large area, reduces the contact resistance with the solder strip, and ensures that the amount of solder paste consumed by the solder pad 30 is small.

[0067] Based on the above embodiments, optionally, the line width of conductor segment 31 is 100 micrometers to 400 micrometers;

[0068] The pad 30 has a size of 800-1100 micrometers along the first direction X, and the pad 30 has a size of 800-1100 micrometers along the second direction Y.

[0069] Specifically, if the linewidth of conductor segment 31 is too small, it will increase the difficulty of the manufacturing process; if the linewidth is too large, the reduction in paste consumption will be insufficient. By setting the linewidth of conductor segment 31 to 100-400 micrometers, the manufacturing difficulty of conductor segment 31 can be reduced while significantly reducing paste consumption. Using the above dimensions for pad 30 and conductor segment 31 reduces the silver paste consumption of solder 30 by 5-10 mg.

[0070] This application also provides a battery assembly, including the solar cell described in the above embodiments.

[0071] A battery module may include multiple solar cells, which can be connected in series to form a battery string. The battery strings can be connected in series, in parallel, or in a series-parallel combination to achieve current output. For example, the connection between individual cells can be achieved by welding ribbons, or the connection between battery strings can be achieved by busbars.

[0072] The battery module may also include a metal frame, a backsheet, photovoltaic glass, and an encapsulating film. The encapsulating film can be filled between the light-facing side of the solar cell and the photovoltaic glass, the back-facing side and the backsheet, and adjacent cells. As a filler, it can be a transparent colloid with good light transmittance and aging resistance; for example, EVA film or POE film can be used, and the choice is based on the specific circumstances and is not limited here. The photovoltaic glass can cover the encapsulating film on the light-facing side of the solar cell. The photovoltaic glass can be ultra-clear glass, which has high light transmittance, high transparency, and superior physical, mechanical, and optical properties. For example, the light transmittance of ultra-clear glass can reach over 92%, which can protect the solar cell while minimizing the impact on its efficiency. Simultaneously, the encapsulating film can bond the photovoltaic glass and the solar cell together, and its presence provides sealing, insulation, waterproofing, and moisture protection for the solar cell.

[0073] The backsheet can be attached to the encapsulating film on the back side of the solar cell. The backsheet protects and supports the solar cell, providing reliable insulation, water resistance, and aging resistance. Multiple backsheet options are available, typically including tempered glass, acrylic glass, and aluminum alloy TPT composite encapsulating film, etc., with specific choices depending on the circumstances. The backsheet, solar cell, encapsulating film, and photovoltaic glass can be mounted on a metal frame. The metal frame serves as the main external support structure for the entire battery module, providing stable support and installation. For example, the battery module can be installed at the desired location using the metal frame.

[0074] The battery module in this application embodiment belongs to the same application concept as the solar cell described in the above embodiments of this application and has corresponding beneficial effects. For technical details not covered in this embodiment, please refer to the solar cell described in any embodiment of this application.

[0075] This application also provides a photovoltaic module, including the battery module described in the above embodiments.

[0076] Photovoltaic systems can be applied in photovoltaic power plants, such as ground-mounted, rooftop, and floating power plants, as well as in equipment or devices that utilize solar energy to generate electricity, such as user solar power supplies, solar streetlights, solar cars, and solar buildings. Of course, it's understandable that the application scenarios of photovoltaic systems are not limited to these; that is, photovoltaic systems can be applied in all fields that require solar energy to generate electricity. Taking a photovoltaic power generation network as an example, a photovoltaic system can include photovoltaic arrays, combiner boxes, and inverters. A photovoltaic array can be a combination of multiple battery modules; for example, multiple battery modules can form multiple photovoltaic arrays. The photovoltaic arrays are connected to combiner boxes, which collect the current generated by the photovoltaic arrays. The collected current flows through an inverter and is converted into AC power required by the mains grid before being connected to the mains grid to achieve solar power supply.

[0077] The beneficial effects of the photovoltaic system in this embodiment are equivalent to the beneficial effects of the battery module described above, and will not be repeated here.

[0078] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.

[0079] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A solar cell, characterized in that, include: A substrate, wherein a plurality of collection grid lines are disposed on a first surface of the substrate, the plurality of collection grid lines being spaced apart along a first direction; each collection grid line includes a plurality of grid line segments disposed along a second direction; wherein the first direction and the second direction intersect each other. A pad is provided between two adjacent gate line segments, and the pad is in contact with the two adjacent gate line segments; the pad includes multiple conductive segments; the multiple conductive segments are arranged sequentially along a first direction, or the multiple conductive segments are arranged sequentially along a second direction, or the multiple conductive segments are arranged around a preset point of the pad.

2. The solar cell according to claim 1, characterized in that: When multiple conductor segments are positioned around a pad at a preset point: The first ends of the plurality of conductor segments of the pad are connected to each other, or the pad may further include a first central portion, with the plurality of conductor segments arranged around the first central portion and the first ends of the plurality of conductor segments electrically connected to the first central portion.

3. The solar cell according to claim 2, characterized in that: The first central part is circular, elliptical, semi-circular, semi-elliptical, fan-shaped, or polygonal; The first central portion has a dimension of 400 micrometers to 550 micrometers along the first direction, and the first central portion has a dimension of 400 micrometers to 550 micrometers along the second direction.

4. The solar cell according to claim 1, characterized in that: When multiple conductor segments are arranged sequentially along the first direction: The pad further includes a second central portion, the width of which along the first direction is greater than the width of which the conductor segment along the first direction; a plurality of conductor segments are respectively disposed on both sides of the second central portion along the first direction, and the gate segment is connected to the second central portion.

5. The solar cell according to claim 4, characterized in that: The second central part is a polygon; The second central portion has a dimension of 400-550 micrometers along the first direction, and the second central portion has a dimension of 800-1100 micrometers along the second direction.

6. The solar cell according to claim 1, characterized in that: When multiple conductive segments are arranged sequentially along the second direction: The pad also includes a connecting portion, which connects to a plurality of the conductor segments, and the gate segment is connected to any of the conductive segments.

7. The solar cell according to claim 6, characterized in that: The plurality of said conductor segments are located on one or both sides of the connecting portion along the second direction, and the grid wire segments are connected to the connecting portion; The dimension of the connecting part along the first direction is 400 micrometers-550 micrometers, and the dimension of the connecting part along the second direction is 800 micrometers-1100 micrometers.

8. The solar cell according to claim 1, characterized in that: The linewidth of the conductor segment is 100 micrometers to 400 micrometers; The pad has a size of 800-1100 micrometers along the first direction and a size of 800-1100 micrometers along the second direction.

9. A battery assembly, characterized in that, Includes the solar cell as described in any one of claims 1 to 8.

10. A photovoltaic system, characterized in that, Includes the battery assembly as described in claim 9.

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