Solar unit for operation on open spaces, especially those used for agricultural purposes, photovoltaic system including such a unit, and methods for operating such a solar unit.

Abstract

Solar unit (5) for operation on open areas, especially those used for agriculture, with several photovoltaic modules (11, 12, 13) and with a frame structure (15) supporting the photovoltaic modules (11, 12, 13), wherein the frame structure (15) is a mobile frame structure (15) which stands freely on the ground, and wherein the solar unit (5) has liquid storage for a liquid for ballasting the solar unit (5), characterized by that the liquid storage tubes (17, 18) of the frame structure (15) are and that the frame structure (15) has skids formed by the storage tubes (17, 18) by means of which the solar unit (5) stands on the ground and on which the solar unit (5) can slide over the ground in order to be able to move the solar unit (5) to another location, in particular from one field to another field

Description

[0001] The invention relates to a solar power unit for operation on open spaces, particularly those used for agricultural purposes, according to the preamble of claim 1. The invention further relates to a photovoltaic system with at least one solar power unit according to the invention. The invention also relates to a method for operating the solar power unit according to the invention.

[0002] A solar unit comprises several photovoltaic modules and a frame structure supporting them. It is known to install such solar units on foundations spaced apart in a field, leaving strips between them accessible to agricultural vehicles. Grass typically grows permanently directly beneath the solar units, occasionally mowed from these strips or grazed by animals such as sheep. Consequently, the field's agricultural use is limited. Due to the strips between the solar units and the resulting low density of photovoltaic modules in the field, this known photovoltaic system provides only limited solar energy.

[0003] To improve agricultural use of the field, it is also known to install photovoltaic modules on a fixed frame with stands, positioned high above the field to allow access for agricultural machinery underneath. However, such a construction is complex and expensive to manufacture. Agricultural use is still hampered by the stands. Finally, the photovoltaic modules must be sufficiently translucent to ensure that all plants growing beneath them receive enough sunlight for their growth. This limits the selection of plant varieties that can be cultivated in the field and also reduces the potential yield and thus the availability of solar-generated energy.

[0004] From US 2016 / 0344330 A1, a transportable solar energy system with solar cells and a frame supporting the solar cells is known. The frame can be mounted on wheels or, according to a described variant, on removable skids. Ballast tanks can also be provided on the frame. DE 20 2016 106 604 U1 discloses a mounting system for solar roofs, the support of which, in a preferred embodiment, consists of a liquid-filled register structure. This register structure enables ballasting of the mounting system and simultaneously serves for heat transfer.

[0005] WO 2022 / 098144 A1 also discloses a wheeled trailer equipped with a solar energy unit.

[0006] The invention is based on the objective of providing a solar unit, a photovoltaic system and a method for operating a solar unit, which enable cost-effective improved use of open spaces for solar energy generation.

[0007] The invention solves this problem with a solar unit according to claim 1, with a photovoltaic system according to claim 7 and with a method for operating a solar unit according to claim 11. Advantageous embodiments of the invention are specified in the dependent claims.

[0008] In a solar power unit for operation on open areas, particularly agricultural ones, with several photovoltaic modules and a frame structure supporting the photovoltaic modules, wherein the frame structure is a mobile frame structure that stands freely on the ground, and wherein the solar power unit has liquid storage tanks for a liquid for ballasting the solar power unit, it is essential to the invention that the liquid storage tanks are storage tubes of the frame structure and that the frame structure has skids formed by the storage tubes, by means of which the solar power unit stands on the ground and on which the solar power unit can slide over the ground in order to be able to move the solar power unit to another location, in particular from one field to another field.

[0009] In an inventive method for operating a solar unit, which is designed according to one of its possible embodiments according to the invention, comprising several photovoltaic modules and a frame structure supporting the photovoltaic modules, which stands freely on the ground as a mobile frame structure, and in which storage tubes of the frame structure are used as liquid storage for liquid to ballast the solar unit, on open areas, in particular agriculturally used, it is provided that the solar unit is pulled to another location, in particular from one field to another field, and thereby glides over the ground on skids formed by the storage tubes of the frame structure and by means of which the solar unit stands on the ground.

[0010] Thanks to the invention, a conventionally cultivated field after harvest, or an otherwise fallow crane pad next to a wind turbine, can be used for solar energy generation by placing the solar units with their inventively mobile frame structures on it. The liquid stored in the frame structure provides sufficient ballast for the solar units, eliminating the need for fixed foundations on the crane pad or in the field. The field with the solar units placed on it does not need to be cultivated during this time. Furthermore, it is advantageous if the field is left fallow for a period of time or at least not used for commercial cultivation of crops such as grain.Therefore, the solar units can be placed very close together on the field, regardless of whether the field is accessible and regardless of shading, so that a high electrical energy yield per unit area is achieved by means of all solar units placed on the field.

[0011] In an advantageous embodiment of the solar unit according to the invention, the photovoltaic modules have heat exchangers on their rear sides. These heat exchangers, together with the storage tubes, are integrated into at least one circuit in which the fluid circulates, and the fluid circulating in the respective circuit flows through them to cool the respective photovoltaic module. According to the method, the photovoltaic modules are cooled by the fluid circulating in the respective circuit. This counteracts a reduction in the efficiency of the photovoltaic modules due to overheating.

[0012] In one embodiment of the invention, the liquid is water, which can also be easily drained if necessary, for example if the solar unit is to be moved to another location.

[0013] According to an alternative and preferred embodiment of the solar unit, a redox flow battery with two electrolyte solutions circulating in separate circuits for the chemical storage of electrical energy is integrated into the solar unit, and the storage tubes designed as liquid reservoirs for the liquid are designed as electrolyte reservoirs for the electrolyte solutions. In a correspondingly advantageous embodiment of the method, electrical energy is chemically stored in the redox flow battery, with the storage tubes designed as liquid reservoirs for the liquid being used as electrolyte reservoirs for the electrolyte solutions.

[0014] Thanks to the integration of the redox flow battery into the solar unit, solar-generated electrical energy can be stored chemically using electrolyte solutions, enabling the provision of electrical energy even at night or on demand, for example, to locally charge the battery of an electric vehicle. Alternatively or additionally, the solar-generated electrical energy can be fed directly into the power grid via an existing grid connection after its generation or after intermediate storage.

[0015] The lower tubes of the frame structure, which also serve as storage tubes and skids, allow the solar unit to be towed without the need for wheels. Advantageously, the skids are parallel to each other and aligned with the length of the solar unit. The skids distribute the load, preventing the solar unit from sinking into the ground and becoming stuck. Furthermore, thanks to the fluid within the skids, the solar unit's center of gravity is advantageously low, ensuring high stability without the need for foundations.

[0016] The photovoltaic modules of the solar unit are preferably arranged on the frame structure at an angle to the longitudinal direction of the solar unit relative to its base, i.e., in particular, at an angle perpendicular to the orientation of the skids. The solar units can thus preferably be arranged approximately in an east-west direction on the fallow crane area or field, with the photovoltaic modules oriented obliquely towards the south.

[0017] Advantageously, the electrolyte solution is arranged in parts of the frame structure further away from the skids, so that no separate lines are required. In particular, the frame structure is designed to include conduit pipes that serve as fluid lines for the liquid, especially as electrolyte lines for the electrolyte solutions. These conduit pipes are preferably connected to the skids in a fluid-conducting manner.

[0018] In an advantageous embodiment of the system, the connecting pipes link the skids (i.e., the energy storage units) of the redox flow battery integrated into the solar unit to other components of the redox flow battery. In particular, the solar unit is provided with at least one pump in each circuit for pumping the respective electrolyte solution through the electrolyte lines assigned to that circuit. Furthermore, the solar unit is provided with a galvanic cell for ion exchange between the electrolyte solutions in the circuits. The galvanic cell is thus integrated into both circuits. Even when using water as the liquid, preferably at least one circuit with at least one pump is provided to circulate the water for cooling the photovoltaic modules.

[0019] The solar unit is specifically designed to store electrical energy supplied by the photovoltaic modules in the redox flow battery. Preferably, the solar unit is connected to an external power grid, particularly the public power grid, for feeding electrical energy into the grid. Alternatively, the solar-generated and, if necessary, temporarily stored energy is supplied locally.

[0020] In a further development of the invention, the solar unit is designed to dimension the electrical energy fed into the external power grid depending on the electrical energy provided by the photovoltaic modules and the state of charge of the redox flow battery.

[0021] In a further embodiment of the invention, the solar unit is configured to feed the electrical energy supplied by the photovoltaic modules into the external power grid up to a defined limit and to store any electrical energy exceeding this limit in the redox flow battery. It is advantageous to adjust this defined limit depending on the state of charge of the redox flow battery.

[0022] A photovoltaic system according to the invention comprises at least one solar unit according to one of its embodiments, which is placed on an open area. In one embodiment of the invention, the open area on which the solar unit is placed is the crane platform of a wind turbine. Such crane platforms are provided next to the base of wind turbines to allow a crane to be erected there for the construction or maintenance of the respective wind turbine. Otherwise, these crane platforms are generally unused. By placing at least one solar unit according to the invention on the crane platform, this crane platform can be put to practical use.

[0023] The solar-generated energy can be fed into the public power grid via the existing feed-in device for the wind turbine. Specifically, the photovoltaic system is electrically connected to the wind turbine, with at least one solar unit connected to an external power grid, particularly the public grid, via a feed-in device of the wind turbine. In embodiments with an integrated redox flow battery, it can also be provided that wind power is temporarily stored in the redox flow battery during peak loads.

[0024] Another embodiment of the photovoltaic system according to the invention comprises several solar units according to one of its embodiments, which, in particular with their longitudinal directions aligned parallel to each other, stand on a field of an agriculturally used open area and are connected to an external power grid, in particular to the public power grid, via a common feed-in device.

[0025] Further embodiments are described in the claims, the accompanying drawings, and the following description of a particularly preferred embodiment of the invention illustrated in the drawings. The drawings show: Fig. 1: a solar unit according to an embodiment of the invention in a simplified representation in a side view; and Fig. 2: the solar unit of Fig. 1 in a top view.

[0026] In the Fig. 1 and Fig. Figure 2 shows a solar unit 5 according to the invention, comprising a plurality of photovoltaic modules arranged side by side in three rows, of which a photovoltaic module 11 in the first row, a photovoltaic module 12 in the second row, and a photovoltaic module 13 in the third row are designated by way of example. The solar unit 5 has a frame structure 15 which supports the photovoltaic modules 11, 12, and 13. The frame structure 15 includes storage tubes 17 and 18, as well as line tubes 19 and 20 and further unnamed line tubes, and optionally connecting lines that are not part of the frame structure 15. The storage tubes 17 and 18 form sliding skids aligned parallel to each other, with which the solar unit 5 rests on the substrate and on which the solar unit 5 can be pulled slidingly over the substrate in a pulling direction 8. The storage tubes 17 and 18 are aligned parallel to the pulling direction 8.Storage pipes 17 and 18 are in . Fig. 2 are arranged essentially concealed beneath the photovoltaic modules 11, 12, 13 and are therefore only visible at their protruding ends.

[0027] To pull the solar unit 5 in the direction of pull 8, a pulling element 23 in the form of at least one pull cable is attached to the frame structure 15 at two attachment points. In particular, the pulling element 23 is attached to the storage tubes 17 and 18, but can alternatively also be attached, for example, to the conduit tubes 19 and 20, preferably in their lower region.

[0028] Storage tubes 17 and 18 are each filled with an electrolyte solution to ballast the solar unit 5 and thus simultaneously serve as electrolyte storage for a redox flow battery integrated into the solar unit 5. The connecting tubes 19 and 20, as well as any connecting lines present, are electrolyte lines for the electrolyte solution and connect the storage tubes 17 and 18 to the photovoltaic modules 11, 12, and 13. This forms two separate circuits of the redox flow battery, each with a pump (not shown) for circulating the electrolyte solution. These circuits are routed past each other in a galvanic cell (also not shown), where ion exchange takes place, generating or releasing electrical energy. Heat exchangers are formed on the back of the photovoltaic modules 11, 12, and 13, through which the electrolyte solutions flow.The electrolyte solutions thus ensure the removal of heat and counteract excessive heating of the photovoltaic modules 11, 12, 13.

Claims

[1] Solar unit (5) for operation on open areas, especially those used for agriculture, with several photovoltaic modules (11, 12, 13) and with a frame structure (15) supporting the photovoltaic modules (11, 12, 13), wherein the frame structure (15) is a mobile frame structure (15) which stands freely on the ground, and wherein the solar unit (5) has liquid storage for a liquid for ballasting the solar unit (5), characterized by , that the liquid storage tubes (17, 18) of the frame structure (15) are and that the frame structure (15) has skids formed by the storage tubes (17, 18) by means of which the solar unit (5) stands on the ground and on which the solar unit (5) can slide over the ground in order to be able to move the solar unit (5) to another location, in particular from one field to another field [2] Solar unit (5) according to claim 1, characterized by , that the photovoltaic modules (11, 12, 13) have heat exchangers on their rear sides which, together with the storage tubes (17, 18), are integrated into at least one circuit in which the respective liquid circulates, for the purpose of cooling the photovoltaic modules (11, 12, 13) and can be permeated by the liquid circulating in the respective circuit for the purpose of cooling the respective photovoltaic module (11, 12, 13). [3] Solar unit (5) according to any one of the preceding claims, characterized by , that a redox flow battery with two electrolyte solutions circulating in separate circuits for chemical storage of electrical energy is integrated into the solar unit (5) and that the storage tubes (17, 18) designed as liquid storage for the liquid are designed as electrolyte storage for the electrolyte solutions. [4] Solar unit (5) according to any one of the preceding claims, characterized bythat the skids are parallel to each other and in the longitudinal direction of the solar unit (5). [5] Solar unit (5) according to any one of the preceding claims, characterized by , that the photovoltaic modules (11, 12, 13) are arranged on the frame structure (15) at an angle to the longitudinal direction of the solar unit (5) relative to its base surface. [6] Solar unit (5) according to any one of the preceding claims, characterized by , that the frame structure (15) has conduit pipes (19, 20) which are designed as fluid lines for the fluid. [7] Photovoltaic system with at least one solar unit (5) according to one of the preceding claims, which is placed on an open area. [8] Photovoltaic system according to claim 7, characterized by , that the open area on which the solar unit (5) is placed is a crane area of ​​a wind turbine. [9] Photovoltaic system according to claim 8, characterized bythat the photovoltaic system is electrically connected to the wind power plant, wherein the at least one solar unit (5) is connected to an external power grid, in particular the public power grid, via a feed-in device of the wind power plant. [10] Photovoltaic system according to claim 7 with several solar units (5) according to one of claims 1 to 6, which, in particular with their longitudinal directions aligned parallel to each other, are located on a field of an agriculturally used open area and are connected to an external power grid, in particular to the public power grid, via a common feed-in device. [11] Method for operating a solar unit (5) designed according to one of claims 1 to 6, comprising several photovoltaic modules (11, 12, 13) and a frame structure (15) supporting the photovoltaic modules (11, 12, 13), which stands freely on the ground as a mobile frame structure, and in which storage tubes (17, 18) of the frame structure (15) are used as liquid storage for liquid to ballast the solar unit (5), on, in particular, agriculturally used, open areas, wherein the solar unit (5) is pulled to another location, in particular from one field to another field, and thereby slides over the ground on skids formed by the storage tubes (17, 18) of the frame structure (15) and by means of which the solar unit (5) stands on the ground. [12] Method according to claim 11, characterized by, that the photovoltaic modules (11, 12, 13) are cooled, wherein heat exchangers, which the photovoltaic modules (11, 12, 13) have on their rear sides and which together with the storage tubes (17, 18) are integrated into at least one circuit in which the respective liquid circulates, are through which the liquid circulating in the respective circuit flows for the purpose of cooling the respective photovoltaic module (11, 12, 13). [13] Method according to claim 11 or claim 12, characterized by , that electrical energy is chemically stored in a redox flow battery integrated into the solar unit (5) with two electrolyte solutions circulating in separate circuits, wherein the storage tubes (17, 18) designed as liquid storage for the liquid are used as electrolyte storage for the electrolyte solutions.

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