IL315286B2 - Agrivoltaic dual-purpose structure with distributed columns enabling high utilization of land for planting and including built in track for robotic cleaning system - Google Patents

Description

AGRIVOLTAIC DUAL-PURPOSE STRUCTURE WITH DISTRIBUTED COLUMNS ENABLING HIGH UTILIZATION OF LAND FOR PLANTING AND INCLUDING BUILT IN TRACK FOR ROBOTIC CLEANING SYSTEM TECHNOLOGICAL FIELDThe present disclosure relates to the field of agrivoltaics, and more specifically, but not exclusively, to an installation of an agrivoltaic solar farm with distributed supports, enabling a high utilization of the land for planting, and incorporating a built-in track for a cleaning robot for the solar panels.

BACKGROUND OF THE INVENTION Agrivoltaics refers to a system in which land underneath raised solar panels is utilized for agricultural purposes. The solar panels are installed at an elevation of approximately 5-6 meters off the ground, and create a micro-climate for growth of crops below them. By applying this dual use concept, the farmer maximizes land utilization, at significantly reduced water consumption. In order for agrivoltaics to be cost-effective, it is necessary to maintain a high yield of the crops grown underneath the solar panels. Indeed, several countries condition subsidies for agrivoltaic installations on whether the relative yield of crops planted in the installation, compared to crops planted in a standard field, reaches a minimum level of productivity. For example, in Japan this minimum is 80% yield, and in Germany this minimum is 66% yield. See generally Dupraz, Christian. "Assessment of the ground coverage ratio of agrivoltaic systems as a proxy for potential crop productivity." Agroforestry Systems (2023): 1-18. Among the factors that influence agricultural yield in agrivoltaic installations is the amount of land that is sacrificed for the structures of the photovoltaic system. Much land is required for items such as posts, electric systems, support structures, guy cables, and access tracks for maintenance. According to Dupraz, cited above, the typical "lost area" of a field having an agrivoltaic installation is around 10%, but may range to as high as 30%, or even higher. Obviously, any "lost areas" cannot contribute to the agricultural yield. In fields with a large percentage of "lost areas," in order to meet regulatory targets for agricultural yield, it is necessary to reduce the ground coverage ratio of the solar panels (the ratio of area of photovoltaic panels to area of land). This reduction makes the entire venture less profitable. In many cases, the percentage of "lost areas" in agrivoltaic fields is higher than necessary, because the solar panels are built using conventional construction strategies, which are not necessarily motivated by the need to minimize ground space. Examples of such conventional construction strategies are found in FIGS. 19A-19B. FIG. 19A illustrates an agrivoltaic installation in Chiba, Japan, over a wheat crop. The distance between stanchions is 4 meters, and the ratio of cropped area to the total field area is 75%. FIG. 19B illustrates an agrivoltaic installation in Fukushima, Japan, also over a wheat crop. In this example, the distance between post lines is only 2 meters, and the cropped area is just 50% of the total field. In addition to the loss of agricultural space, the proliferation of stanchions also causes a higher risk for accidental structural damage by farming machines. Solar tracking refers to a method of operation of solar panels in which the panels are rotated throughout the day. The purpose of solar tracking is to maintain the photovoltaic panels as close as possible to a 90˚ angle to the sun throughout the day, thereby maximizing the energy received from the sun’s rays. Various strategies currently exist for performing solar tracking. The most economical and common type is a "single axis tracker," in which the solar panels are affixed to a N/S horizontal axis or an E/W horizontal axis, such as a rod, and the rod is rotated in its entirety with the solar panels attached thereto. A truss is a framework, typically consisting of rafters, posts, and struts, supporting a roof, bridge, or other structure. Trusses may be used to support agrivoltaic structures. One such example is illustrated in FIG. 19C, in which transverse trusses support a roof frame, a portion of which is covered by fixed photovoltaic panels. Solar panels require regular cleaning in order for them to perform at maximum efficiency. Various types of robots have been developed capable of coping with two main types of field layouts. One field type is comprised of a 100% panels coverage, allowing for a cleaning robot to move freely in all directions. The second field type is comprised of multiple parallel rows of panels, evenly spaced between each other, allowing either manual cleaning by hopping from row to row or by using a fully autonomous, fully automatic cleaning system, comprised of a robot and a mobile base. In the second field type, one common strategy for transporting the robot is to have a cart dimensioned to travel on a ground path adjacent to the rows of solar panels. While this basic approach is certainly effective, in the context of agrivoltaic installations, it is disfavored, because it causes sacrifice of even more land that would be otherwise available for planting.

SUMMARY OF THE INVENTION The present disclosure introduces a novel support system for rows of photovoltaic panels in agrivoltaic installations. The support system minimizes the number of stanchions required to support rows of photovoltaic panels. In addition, the support system includes a built-in track, allowing for linear motion for a cleaning robot for the solar panels, as well as a mobile base station of the cleaning robot. The built-in track is formed out of a box truss that supports the rows of photovoltaic panels. The construction system is based on a novel profile design. A profile is a basic building block of construction, which is typically used in the assembly of structural frames. In the present disclosure, when installed as part of the interior rows supporting the solar panels, the profiles serve a dual function – both as a framing element and as an axis for rotation of the solar panel. Specifically, the profiles feature two opposed flat faces and two opposed faces that are at least partially rounded. The rounded portions together make up the circumference of a circle. The opposed rounded faces serve as guides for rotation of the solar panels around the profiles. The faces include exterior grooves that enable connections between parallel profiles in a conventional manner. In some embodiments, the edges of the grooves are equipped with a frictional surface, to ensure stable contact between the profile and bolts that are inserted therein. In particularly advantageous embodiments, the same profile, or a profile with the same proportions, is used as a building block for construction of the entire raised photovoltaic structure. In other words, in theory, any framing element may be used for construction of the portions of the frame that do not bear rotating solar panels, such as the box trusses of the edge rows of the array and the columns supporting the array. Nevertheless, it is advantageous to use the same profile for those portions as well. Advantageously, the raised structure of photovoltaic panels is thus built in an entirely modular manner, and it may be rearranged or rebuilt as desired. In preferred embodiments, the edge rows also serve as tracks for movement of a solar cleaning robot. The solar cleaning robot has an independent mobile base which moves laterally along the edge support rows. When the base reaches a given interior row, the robot leaves the base, activates it rotating brushes, moves along the line of panels, and returns back to the base station. Because the edge rows are anyways present as part of the structure, it is not necessary to dedicate any extra land for transport of the cleaning robot. Utilizing the structure described herein, a raised agrivoltaic structure may be built with a maximum percentage of land underneath the structure available for agricultural use. In addition, the raised agrivoltaic structure maintains an ability to rotate the solar panels in order to track the sun and to have the solar panels cleaned regularly. According to a first aspect, a profile includes two opposed linear edges, and two opposed edges that are at least partially curvilinear. The linear edges and curvilinear edges are arranged sequentially to form a tube having a central internal cavity. An external groove is configured along an extent of each of the linear and curvilinear edges. Optionally, the four external grooves are identical in width and depth. Optionally, a frictional surface surrounds outer edges of each of the grooves. The profile serves multiple purposes, including a support structure of the solar farm, and an axis of rotation of solar panels built on the solar farm. According to a second aspect, a three-dimensional assembly for supporting a row of rotatable solar panels is disclosed. The assembly is built, at least in part, from a plurality of the profiles. The assembly includes: an upper row and a lower row arranged in parallel, each of the upper and lower rows comprising two or more of the profiles arranged linearly, a plurality of internal connectors spanning the central internal cavities of adjacent profiles, and a plurality of struts connecting between external grooves of the parallel profiles that are facing each other. A plurality of rotatable panels are arranged on panel connectors that are on the upper row. Optionally, the panel connectors each include one or more sleeves that are dimensioned to fit around the upper row and to rotate around the curvilinear edges of the one or more profiles of the upper row. The sleeves may be configured on the upper row at locations without any connections to struts, thereby permitting free rotation of the panels. The rotatable panels may be configured to rotate around an angle of 180 degrees. The rotatable panels may be solar panels. A motor may be arranged on the structure and configured to rotate the solar panels so as to track the sun.

The assembly may include at least one bracket for joining multiple struts and connecting said multiple struts to the external grooves of the parallel profiles. A bracket may be fixed within the external groove of two adjacent profiles, such that two adjacent profiles are held in place by both an internal connector and at least one bracket. An elevated solar farm may be built from a plurality of the interior profiles. The solar farm includes: a plurality of interior rows arranged in a first horizontal direction, each interior row comprising upper and lower sets of two or more of the profiles arranged linearly, wherein internal connectors span the internal cavities of adjacent profiles, and wherein the upper and lower sets are arranged vertically aligned one over the other. A plurality of struts are arranged as a truss connecting between the external grooves of the parallel profiles that aligned one over the other. A plurality of solar panels are rotatably arranged on the upper set of each of the interior rows. Two edge rows are arranged at ends of the interior rows. Each edge row includes four sets of the profiles arranged in a rectangular orientation, a plurality of internal connectors spanning the internal cavities of adjacent profiles, and a plurality of struts arranged as a truss connecting between the external grooves of parallel profiles. A plurality of edge connectors connect between the internal cavities of profiles of the interior rows and the external groove of the profiles of the edge rows. A plurality of vertical columns support the edge rows, each column comprising four sets of the profiles arranged in a rectangular orientation. A plurality of internal connectors spanning the internal cavities of adjacent profiles. A plurality of struts are arranged as a truss connecting between the external grooves of parallel profiles. Optionally, the solar panels are arranged on panel connectors, wherein each panel connector comprises one or more sleeves that are dimensioned to fit around the upper set of profiles of each interior row and to rotate around the curvilinear edges of said profiles. Optionally, the sleeves are configured on the upper row at locations without any connections to struts, thereby permitting free rotation of the panels. Optionally, the panels are configured to rotate around an angle of 180 degrees. The solar farm may include at least one bracket for joining multiple struts between parallel profiles and connecting said multiple struts to the external grooves of the parallel profiles. The bracket may be fixed within the external groove of two adjacent profiles, such that two adjacent profiles are held in place by both an internal connector and at least one bracket.

The edge rows may be built of profiles having a different size than the profiles of the interior rows. The profiles of the edge rows may have the same cross section as the profiles of the interior rows. In preferred embodiments, the interior rows and edge rows are configured at a height suitable for permitting agricultural growth underneath the interior rows. The elevated solar farm may include a cleaning robot assembly configured to clean the solar panels arranged on each interior row. The cleaning robot assembly may include a base, the base comprising wheels dimensioned to roll along the profiles of the edge rows; and a cleaning robot configured to travel from the base along the panels of each interior row. The base may include a solar panel sufficiently large for recharging the cleaning robot for continuous overnight cleaning. The elevated solar farm may be part of an agrivoltaic installation including crops planted underneath the interior rows. A total percentage of the square area of the ground taken up by the columns, relative to the square area of the ground delineated by the edge rows and interior rows, may be less than 2%. In another aspect, a method of solar tracking of solar panels is disclosed. The method includes: mounting solar panels on panel connectors each having a sleeve; arranging the sleeves of the panel connectors around a row comprised of a profile having at least two opposed at least partially curvilinear edges; and rotating the panel connectors around the curvilinear edges of the profile. Optionally, the method includes rotating the panel connectors around an arc of up to 180˚. In another aspect, a method of cleaning an array of solar panels is disclosed. The solar panels are arranged on interior rows bounded by edge rows that are perpendicular to the interior rows. The method includes: transporting a cleaning robot along an edge row on a first base until the cleaning robot is aligned with an interior row; moving the cleaning robot from the base to the interior row; cleaning the interior row while moving the cleaning robot along said interior row; returning the cleaning robot to the first base or to a second base located on a second edge row that is at an opposite side of the interior row; transporting the cleaning robot on the first base or second base to a subsequent interior row in the array, and cleaning the solar panels of the subsequent interior row; and repeating the moving, cleaning, returning, and transporting steps until the entire array is cleaned. Optionally, the method further includes, following the cleaning of the entire array, returning the cleaning robot to the base, and charging the cleaning robot at the base from energy captured from a solar panel mounted on the base. If necessary, the cleaning robot may be charged by a connection to grid power, depending on the state of charge of the battery and of the base.

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: FIG. 1A illustrates a cross-section view of a profile, according to embodiments of the present disclosure; FIG. 1B illustrates a cross-section view of an internal sleeve suitable to be inserted in the profile of FIG. 1A, according to embodiments of the present disclosure; FIG. 2illustrates a side view of the profile of FIG. 1A ; FIG. 3illustrates a perspective view of the profile of FIG. 1A ; FIG. 4Ais a perspective view of a solar farm built of interior rows, exterior rows, and columns all made of the profile of FIG. 1A; FIG. 4Bis a zoomed-in view of the solar farm of FIG. 4A; FIG. 4Cis a top view of the solar farm of FIG. 4A; FIG. 4Dis a further zoomed-in perspective view of the solar farm of FIG. 4A; FIG. 4Eis a side view of the solar farm of FIG. 4A; FIG. 5A illustrates a portion of an interior row, with a solar panel rotatably arranged thereon, according to embodiments of the present disclosure; FIG. 5Billustrates a cross section of the interior row taken along axis A-A of FIG. 5A; FIG. 5C illustrates a cross section of the interior row taken along axis C-C of FIG. 5A; FIG. 5Dillustrates a cross section of the interior row taken along axis B-B of FIG. 5A; FIG. 5Eillustrates a cross-section of the interior row taken along axis D-D of FIG. 5A; FIG. 6is a schematic representation of an interior row with four sets of three solar panels configured thereon, with a different orientation of struts; FIG. 7illustrates a zoomed-in portion of the interior row of FIG. 6, showing the truss between the upper and lower profiles of the interior row, and illustrating the solar panel at a 90 degree angle to the axis of the interior row; FIG. 8illustrates a perspective view of an interior row; FIG. 9illustrates a side view of a connector for mounting a solar panel onto the profile of the interior row of FIG. 5A; FIG. 10illustrates a perspective view of the connector of FIG. 9; FIG. 11illustrates solar panels mounted onto the connectors which are mounted onto the profiles; FIG. 12Aillustrates a strut that may be incorporated in the interior row; FIG. 12Billustrates a bracket that may be incorporated in the interior row; FIG. 12Cillustrates a strut connected to a bracket which is connected to a profile; FIG. 12Dillustrates two brackets connected to a profile; FIG. 13illustrates the rotation of the solar panel around a profile; FIG. 14 illustrates a cross section view of an interior row, including edge connectors; FIG. 15is a perspective view of the edge connector illustrated in FIG. 14 ; FIGS. 16A-Dillustrate an interior row, with the solar panel configured at different angles; FIG. 17is a zoomed-in perspective view of an elevated solar farm, illustrating the connection of the interior rows to the edge rows; FIG. 18 illustrates a cleaning robot base arranged on an edge row of the elevated solar farm, according to embodiments of the present disclosure; and FIGS. 19A-Cillustrate prior art agrivoltaic installations.

DETAILED DESCRIPTION OF EMBODIMENTS The present disclosure relates to the field of agrivoltaics, and more specifically, but not exclusively, to an installation of an agrivoltaic solar farm with distributed supports, enabling a high utilization of the land for planting, and incorporating a built-in track for a cleaning robot for the solar panels. Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not necessarily limited in its application to the details of construction and the arrangement of the components and/or methods set forth in the following description and/or illustrated in the drawings and/or the Examples. The invention is capable of other embodiments or of being practiced or carried out in various ways. As used in the present disclosure, the term "solar panel" refers to a panel designed to absorb the sun's rays as a source of energy for generating electricity or heating. A solar panel is constructed of photovoltaic cells, and utilizes other components such as inverters, controllers, and solar trackers. A "solar farm" is a large-scale array of solar panels used for the production of electricity. Although the present disclosure utilizes profiles for the construction of an agrivoltaic solar farm, the profiles used in the support structures described herein may be used in any suitable installation. Accordingly, in the present disclosure, the profiles are first described as standalone units, followed by a description of the agrivoltaic solar farm that may be constructed with them. Referring to FIGS. 1A, 1B, 2, and 3, FIG. 1A is a cross-section view of the profile 10, FIG. 1B is a cross-section view of a sleeve (also referred to herein as an "internal connector") configured to fit within profile 10, FIG. 2 is a side view of the profile 10, and FIG. 3 is a perspective view of the profile 10. Profile 10 includes two opposed linear edges 12 and two opposed, at least partially curvilinear, edges 14. The curvilinear edges are dimensioned such that they are each along the circumference of a circle 15 that circumscribes the profile 10. The linear edges 12 and curvilinear edges 14 are arranged in sequence to form a tube having a central internal cavity 18. Each edge 12, 14 also has an external groove 16 accessible from the outside of the profile 10. The external groove is dimensioned so as to receive therein a bracket or other suitable connector element, for connecting between different profiles, as will be described further herein. In the illustrated embodiment, the groove 16 has a curved bottom; however, the specific contours of the groove 16 are not critical, and any suitable cross-section shape may be utilized. Preferably, each of the grooves 16 of the four faces of the profile 10 is identical in width and depth, to thereby permit connectors of the same size to be inserted therein. The profile may be made of aluminum or any other suitable material. In exemplary embodiments, a portion 13 of each external face surrounding the cavity 16 may be made in a ribbed or otherwise high-friction finish, in order to promote adherence of the connector element to the profile 10, without slipping.

The profile may be dimensioned in suitable sizes and with suitable tolerances in order to support a structure. In one exemplary embodiment, the circle circumscribed around the profile 10 has a diameter of 120 mm. The wall of the profile may be between and 5 mm thick. Each of the grooves 16 may be 13 mm wide and approximately 9 mm deep. The length of the profile may be between 150 and 200 cm. The foregoing values represent one example, and other dimensions may also be utilized. Referring to FIGS. 4A-4E, the profiles 10 may serve as basic building blocks of an elevated solar farm 100. The solar farm 100 includes interior rows 80, columns 92, and edge rows 94. Each of the interior rows 80 is constructed of an upper and lower row formed of the profiles 10, and connected by an array of struts and connectors. Each of the columns 92 and edge rows 94 is constructed of four rows of the profiles 10, arranged substantially rectangularly, and connected by an array of struts and connectors. In the illustrated embodiment, each interior row 80 includes four rotatable arrays of solar panels, arranged colinearly. As seen best in FIGS. 4C and 4D, vertical connectors 20 connect between upper and lower rows of profiles within each interior row 80, while transverse connectors 76 and 78 provide stabilizing horizontal connections between adjacent interior rows 80. The "interior rows" 80 may also form a standalone assembly, and thus, in the absence of a solar panel, the interior rows may also be referred to as a "three-dimensional assembly." FIG. 5A illustrates an interior row 80 comprised of a plurality of profiles 10. Interior row 80 includes an upper row 82 and lower row 84 arranged in parallel. Each upper row 82 and lower row 84 consists of one or more of the profiles 10 arranged in sequence. When there is more than one profile 10 in a given row, adjacent profiles 10 are connected through insertion of sleeve 110 (shown in FIG. 1B) within the central internal cavity 18. The sleeve 110 is dimensioned in order to fit snugly within the central internal cavity 18 of both profiles 10 that it connects. Still referring to FIG. 5A, a plurality of struts 20 connect between external grooves of the parallel profiles 10 that are facing each other. Each strut includes a hole 21 on either end thereof (location indicated in FIG. 5D), for forming connections thereto. The struts 20 are arranged in a pattern to thereby form a truss. The specific pattern of the truss may be selected according to desired strength properties of the interior row 80, in a manner known to those of skill in the art. The embodiment of FIG. 5A illustrates a triangular truss configuration. The triangles may be equilateral triangles (also known as Warren trusses) or isosceles triangles (also known as Neville trusses). Still referring to FIG. 5A, an array of solar panels 30 is mounted onto the upper row 82. Each solar panel 30 is attached to a connector 31 at either side of the solar panel 30. The connectors 31 are threaded around the upper row 82 in locations not connected to struts, to thereby permit free rotation of the connectors 31 around the upper row 82. FIG. 5B illustrates a cross-section of the upper row 82 in the center of an array of solar panels 30, taken at cut A-A of FIG. 5A. Each connector 31 includes a substantially flat surface 32, a sleeve 34, and a face 36, to which sleeve 34 is attached. The solar panels are arranged over the upper row 82 of the interior row 80. The sleeves 34 are dimensioned to fit around the profiles 10, with the radius of the sleeves 34 being only slightly larger than the radius of the corresponding curvilinear faces 14 of the profiles 10. As a result, the curvilinear faces 14 serve as a basis of rotation for the sleeves 34, and the sleeves 34 rotate smoothly around the profiles 10. FIG. 5C illustrates a cross-section of the upper row 82 at the end of a solar panel array 30, taken at cut C-C of FIG. 5A. In this view, the edge of a connector 31 is visible. An endcap 38 is placed over the profile 10 at this location. Horizontal stabilizing strut is attached to the endcap and extends horizontally to another edge row (out of the page in the view of FIG. 5A). The horizontal stabilizing strut 78 is positioned at the end of the connector 31, in a location in which it does not interfere with rotation of the solar panel 30. FIG. 5D illustrates a cross-section of the upper row 82 in the middle of the solar panel array, taken at cut B-B of FIG. 5A. FIG. 5D illustrates one manner of attachment of struts 20 to the profile 10. In the illustrated embodiments, a hammerhead bolt 19 is inserted into groove 16, with the hammerhead within the groove. A plate 22 is threaded around the bolt and is sealed in place with nut 29. Connector 23 extends from plate and includes a hole. The hole is of the same dimension as hole 21 of the strut 20. A bolt is inserted through both holes, and is sealed in place by nut 42. Because FIG. 5D is a cross-section view that cuts the middle of the bracket connector 23, only a single strut is seen connected to the bracket connector 23. In actuality, bracket connector 23 may have multiple holes which are aligned horizontally, with connections to two struts 20 (as seen in the profile view of the cross-section) or even more.

In the illustrated embodiment, a sleeve 110 is within the internal cavity of the profile 10, and bolts 19 and plates 22 are inserted in all of the grooves 16. This configuration may be used at a junction between two adjacent profiles, in order to secure the adjacent profiles to each other both internally and on all four external faces. FIG. 5E illustrates a cross-section of the lower row 84 in the middle of the solar panel array, taken at cut D-D of FIG. 5A. Two struts are visible: a vertical supporting strut 20 (due to the cross-section view, only one of the two emanating from the bracket is visible), and a lower horizontal stabilizing strut 76, which extends horizontally to another lower row 84 (out of the page in the view of FIG. 5A). The mechanism of connection is the same as that described in FIG. 5D. FIG. 6 illustrates an exemplary embodiment of an internal row 80, and particularly shows how the truss structure of each internal row 80 enables rotation of the solar panels around the upper row 82. The internal row 80 includes four sub-assemblies 81, each containing three solar panels that are affixed one to the other and rotatable with each other. The four subassemblies 81 may each include a separate solar tracking mechanism. FIG. 7 illustrates a subsection of the internal row 80, in the portion of the area marked within the circle of FIG. 6, and exemplifies how the rotation of the solar panels is consistent with the truss structure. As can be seen, brackets 62 are attached to profiles of the upper rows 82 at locations where there are no sleeves 34. Thus, although sleeves completely surround the profiles 10, their movement is not encumbered by the brackets 62 and struts 20. This configuration ensures that the solar panel is able to rotate freely through a 180˚ angle around the upper row 82. The panel is prevented from performing a full 360˚ loop due to the presence of struts 20 at some locations parallel to the panel 30. However, a 180˚ range of motion is sufficient for purposes of solar tracking. In this view, the horizontal stabilizing struts 76 and 78 are not visible, although their locations also do not interfere with the rotation of the solar panels, as discussed. In addition, as seen in FIG. 7, and as previously discussed in connection with FIG. 5E, on the lower row 84, the bracket 62 is configured at location 11, which is the junction between profiles 10a and 10b. This configuration strengthens the connection between adjacent profiles 10a, 10b. FIG. 8 illustrates a perspective view of interior row 80. In this view, a rotation slider 39 is attached to one end of the solar panel connector 31. The slider 39 is attached to an actuator (not shown) that raises and lowers the slider 39 to thereby change the tilt angle of the solar panels 30. Other mechanisms of rotation are possible as well.

FIGS. 9 and 10 provide additional views of the connectors 31, including a side view (FIG. 9) and a perspective view (FIG. 10) of panel connectors 31. Each panel connector 31 includes a substantially flat surface 32, a sleeve 34, and a face 36, to which sleeve 34 is attached. Sleeve 34 is constructed of a material having a low coefficient of friction relative to the material of the profile 10, such as a rubber or a polymer. The solar panels 30 are attached to the panel connector 31 with clips 33, as seen in FIG. 11. FIGS. 12A-12D illustrate components for connecting a strut 20 to the profile. Referring to FIG. 12A, strut 20 is a long, essentially uniform, tubular structure. Strut includes holes 21 at either end thereof, for attachment to the brackets 22. FIG. 12B illustrates a bracket 22 for insertion into the grooves of the profiles 10. As shown in FIG. 12B, bracket 22 includes a region 64 which is sized and shaped to fit within the external grooves 16 of the profiles 10. In the present example, region 64 has a curvature to match the curvature of external grooves 16. Flat region 63 of the bracket 22 is sized and shaped to fit to abut the flat or curvilinear surface of the profile 10. Flat region 63 stabilizes the connection of bracket 22 to groove 56, preventing lateral movement of the bracket 22. As discussed above, prevention of slipping may also be assisted through the frictional surface of the profile. Brackets 22 may be slid into place by insertion into the end of the profile 10. FIG. 12C illustrates an assembly including a profile 10 (part of a lower row), a bracket 22, and a strut 20 bolted to the bracket 22. FIG. 12D illustrates how a bracket may be inserted into any or all of the external grooves 16, as needed for the structure that is being built. In the example of FIG. 12D, two brackets 22 are affixed within opposite faces of the profile 10. Also as seen in FIG. 12D, the location of each bracket 22 may be fixed such that the bracket 22 spans two adjacent profiles 10a and 10b. Thus, the two adjacent profiles 10a, 10b are held in place by both an internal sleeve (not shown) and one or more of the brackets 62. This placement of the bracket 62 helps stabilize the entire interior row. FIG. 13 is a zoomed in view of the sleeve 34 and the profile 50, showing the rotation of the solar panel connector 31 around the profile 10, through curve "c." As can be seen, the sleeve 34 substantially conforms to the dimensions of the curvilinear face 14 of the profile 10. The curvilinear face 14 provides support for the sleeve 34 during its rotation, helping ensure that the rotation proceeds smoothly.

Referring now to FIGS. 14, 15, 16A-D, and 17, and referring back to FIGS. 4A-4E, the assemblies of rows 80 may be integrated into an elevated solar farm. To that end, each of the rows 80 may include endcap connectors 13 on both ends of the upper and lower rows 82, 84. FIG. 14 illustrates a side view of one such row 80, with the endcap connectors 13 shown only from the far end of the row. FIG. 15 is a perspective view of an endcap connector 13. As can be seen, the endcap connector is generally L-shaped, with holes for receiving bolts therethrough for affixing the endcap connector 16 to both the end of the row 80, on a first side, and an edge row that is perpendicular to row 80, on the second side. FIGS. 16A-D illustrate the solar panels 30 in four different rotation positions around assembly 80. The assembly 80 includes endcap connectors 13 visible on both the upper and lower rows. The solar panels 30 are shown in four rotation positions. As is evident to those of skill in the art, the four illustrated positions are merely exemplary, and the solar panels may be rotated around the upper rows around the entire 180 degrees. The elevated solar farm 100 includes multiple interior rows 80 as described, bounded by edge rows 90. For purposes of completeness, each of the elements of the interior rows 80 is recited again herein. Each interior row 80 includes upper and lower sets of the profiles 10 arranged linearly. Internal sleeves span the internal cavities of adjacent profiles. The upper and lower sets of the profiles 10 are arranged vertically aligned one over the other, to form upper row 82 and lower row 84. Struts 20 are arranged as a truss connecting between the external grooves 16 of the parallel profiles 10 that are aligned one over the other. Solar panels 30 are rotatably arranged on the upper row 82 of each of the interior rows 80. Two edge rows 94 are arranged at ends of the interior rows 80. Each edge row is constructed as a box truss. Four sets of the profiles 10 are arranged in a rectangular orientation. As in the interior rows, a plurality of internal connectors 19 span the internal cavities of adjacent profiles, and a plurality of struts 20 and brackets 22 connect between the external grooves of parallel profiles. A plurality of vertical columns 92 support the edge rows 94. Each column 92 is constructed like the edge rows 94, but with a vertical orientation. The columns 92 include four sets of the profiles 10 arranged in a rectangular orientation, a plurality of internal connectors 19 spanning the internal cavities 18 of adjacent profiles 10, and a plurality of struts 20 and brackets 22 arranged as a vertically oriented box truss connecting between the external grooves 16 of parallel profiles 10. The columns 92 may be connected to the edge rows 94 using any suitable means, including through endcap connectors 13. In addition, one or more diagonal braces 95 may be introduced to stabilize the connection between the edge rows 94 and the columns 92. The height of the columns 92 is suitable for permitting agricultural growth underneath the interior rows, e.g., between 2 and meters. The trusses of the edge rows 94 and vertical columns 92 provide great strength to the overall structure, and enable the structure to be constructed with a minimum of vertical columns. For example, in the illustrated embodiment, only six vertical columns are needed to support twenty four rows of solar panels. Advantageously, the minimum number of vertical columns enables more land underneath the solar panels to be dedicated to growing crops, thereby maximizing the crop yield of an agrivoltaic system. Some basic calculations illustrate the efficiency of the described structure. In the example depicted herein, the length of the edge rows is 42 meters. The width of the entire installation, including the edge rows, is approximately 24.8 meters. Thus, the installation has a total area of 1,042 square meters. The width of each of the interior rows is 22.1 meters. The width of each edge row, interior row, and column is 1.2 meters. Thus, each column occupies approximately 1.5 square meters, and the six columns occupy a total area of only 9 square meters, which is less than 1% of the total surface area that would theoretically be available for farming. Even accounting for some additional loss of land for various other materials related to the photovoltaic structures, this still represents a remarkable utilization potential. Thus, the arrangement of the edge rows 94, columns 92, and interior rows permits an extremely high ratio of planted crops relative to the entire field. Furthermore, while not shown, it is also possible to further increase the capacity of the planting underneath the structure by placing interior rows 80 on both sides of edge rows 94. FIG. 17 illustrates a close-up of the edge row 94 and the connection to each interior row 80. The view of FIG. 17 also shows how each edge row 94 is constructed of the exact same elements as the interior rows 80 – including profiles 10, struts 20, and brackets 22. Each edge row 94 is made of four horizontal lines comprised of one or more of the profiles 10, arranged in a rectangular formation. A plurality of horizontal struts 20 are connected between adjacent lines. The struts 20 may join together at brackets, which may be situated at the junctions of two adjacent profiles 10, or may be affixed to the profiles 10 using the hammerhead bolts or any other suitable connectors.

In some embodiments, each of the rows of the edge rows 94 and columns 92 is constructed of the same profile 10 as the interior rows 80. To be clear, unlike the interior rows 80, there is no specific function for the curvilinear faces of the profiles 10 in the edge rows 94 or columns 62. Since no solar panels or other elements rotate around the edge rows 94 and columns 62, the same functions may be achieved equally well with a profile having four flat faces. Nevertheless, it is useful to use the same materials that are used to construct the interior rows in order to construct the edge rows and columns, in order to enable the entire structure to be built in a modular manner. In alternative embodiments, the edge rows 94 are made of a different profile than the interior rows 80. In particular, the edge rows may be made of a profile of the same shape, but of a larger size. In theory, as well, the edge rows 94 may be made of a profile with an entirely different shape as well. Referring now to FIG. 18, edge row 94, in addition to serving as a support for the interior rows, may also serve as a track for a base 401 of a cleaning robot 400. The cleaning robot 400 and base 401 together constitute a cleaning robot assembly. The cleaning robot 400 may include brushes and other suitable materials for removing dust or debris from the surface of the photovoltaic panels. The cleaning robot 400 may travel back and forth along the surface of the panels in each interior row 80, in the direction of arrow 402. After cleaning the panels 30 of each row 80, the cleaning robot 400 mounts back onto the base 401 (or a second base 401 on the opposite edge row, not shown). The base 401 then travels in direction of arrow 404 along the edge row until it is positioned opposite the next interior row 80. The process is repeated, until the cleaning robot 4has cleaned the entire array of solar panels. Base 401 is a docking station that is constructed of a frame 406 and includes wheels 405. The wheels 405 are sized and shaped to match the dimensions of the profiles 10 that form the edge rows 94. In particular, when the curvilinear faces of the profiles face upward in edge rows 94, the wheels 405 may have a substantially concave shape matching the curvature of the profiles, to enable smooth rolling of the wheels 405 over the profiles. Alternatively, the wheels may be shaped so as to roll within the grooves of the profiles 10. Base 401 may further include a solar panel 403. The solar panel 403 may be large enough to provide sufficient power to the cleaning robot so that the cleaning robot may clean the solar panels overnight, when the solar panels are not in use, without additional powering up. The base 401 may also include a connection to an external water source, as well as an optional external grid energy supply for extended cleaning time, typical for large scale photovoltaic (PV) plants. The agrivoltaic system described herein may include a computing system with central controller (not shown). The controller may be used to provide instructions (through cables or wirelessly) to the motors for rotating the solar panels. The controller may also communicate with both the base and the cleaning robot, to thereby enable safe and efficient performance of cleaning tasks.

Claims (9)

-18- 315286/ CLAIMS:

1. A three-dimensional assembly built from a plurality of profiles wherein each profile comprises two opposed linear edges and two edges that are at least partially curvilinear, wherein the linear edges and curvilinear edges are arranged sequentially to form a tube having a central internal cavity, and an external groove configured along an extent of each of the linear and curvilinear edges, the assembly comprising: an upper row and a lower row arranged in parallel, each of the upper and lower rows comprising two or more of the profiles arranged linearly, a plurality of internal connectors spanning the central internal cavities of adjacent profiles, and a plurality of struts connecting between external grooves of the parallel profiles that are facing each other; and a plurality of rotatable panels arranged on panel connectors that are on the upper row. The three-dimensional assembly of claim 1, wherein the panel connectors each comprise one or more sleeves that are dimensioned to fit around the upper row and to rotate around the curvilinear edges of the one or more profiles of the upper row. 3. The three-dimensional assembly of claim 1, wherein the sleeves are configured on the upper row at locations without any connections to struts, thereby permitting free rotation of the panels. 4. The three-dimensional assembly of claim 3, wherein the rotatable panels are configured to rotate around an angle of 180 degrees. 5. The three-dimensional assembly of claim 1, wherein the rotatable panels are solar panels. 6. The three-dimensional assembly of claim 5, further comprising a motor arranged on the structure and configured to rotate the solar panels so as to track the sun. 7. The three-dimensional assembly of claim, further comprising at least one bracket for joining multiple struts and connecting said multiple struts to the external grooves of the parallel profiles. -19- 315286/ 8. The three-dimensional assembly of claim 7, wherein a bracket is fixed within the external groove of two adjacent profiles, such that two adjacent profiles are held in place by both an internal connector and at least one bracket. 9. An elevated solar farm built from a plurality of profiles, wherein each profile comprises two opposed linear edges and two edges that are at least partially curvilinear, wherein the linear edges and curvilinear edges are arranged sequentially to form a tube having a central internal cavity, and an external groove configured along an extent of each of the linear and curvilinear edges, the solar farm comprising: a plurality of interior rows arranged in a first horizontal direction, each interior row comprising upper and lower sets of two or more of the profiles arranged linearly, wherein internal connectors span the internal cavities of adjacent profiles, and wherein the upper and lower sets are arranged vertically aligned one over the other, a plurality of struts are arranged as a truss connecting between the external grooves of the parallel profiles that aligned one over the other; and a plurality of solar panels rotatably arranged on the upper set of each of the interior rows; two edge rows arranged at ends of the interior rows, each edge row comprising four sets of the profiles arranged in a rectangular orientation, a plurality of internal connectors spanning the internal cavities of adjacent profiles, and a plurality of struts arranged as a truss connecting between the external grooves of parallel profiles, a plurality of edge connectors for connecting between the internal cavities of profiles of the interior rows and the external groove of the profiles of the edge rows; and a plurality of vertical columns supporting the edge rows, each column comprising four sets of the profiles arranged in a rectangular orientation, a plurality of internal connectors spanning the internal cavities of adjacent profiles, and a plurality of struts arranged as a truss connecting between the external grooves of parallel profiles. 10. The elevated solar farm of claim 9, wherein the solar panels are arranged on panel connectors, wherein each panel connector comprises one or more sleeves that are dimensioned to fit around the upper set of profiles of each interior row and to rotate around the curvilinear edges of said profiles. 11. The elevated solar farm of claim 10, wherein the sleeves are configured on the upper row at locations without any connections to struts, thereby permitting free rotation of the panels. -20- 315286/ 1

2. The elevated solar farm of claim 11, wherein the panels are configured to rotate around an angle of 180 degrees. 1

3. The elevated solar farm of claim 9, further comprising at least one bracket for joining multiple struts between parallel profiles and connecting said multiple struts to the external grooves of the parallel profiles. 1

4. The elevated solar farm of claim 13, wherein a bracket is fixed within the external groove of two adjacent profiles, such that two adjacent profiles are held in place by both an internal connector and at least one bracket. 1

5. The elevated solar farm of claim 9, wherein the edge rows are built of profiles having a different size than the profiles of the interior rows. 1

6. The elevated solar farm of claim 9, wherein the interior rows and edge rows are configured at a height suitable for permitting agricultural growth underneath the interior rows. 1

7. The elevated solar farm of claim 9, further comprising a cleaning robot assembly configured to clean the solar panels arranged on each interior row, the cleaning robot assembly comprising: a base, the base comprising wheels dimensioned to roll along the profiles of the edge rows; and a cleaning robot configured to travel from the base along the panels of each interior row. 1

8. The elevated solar farm of claim 17, wherein the base comprises a solar panel sufficiently large for recharging the cleaning robot for continuous overnight cleaning. 1

9. The elevated solar farm of claim 9, wherein the solar farm is part of an agrivoltaic installation including crops planted underneath the interior rows. 20. The elevated solar farm of claim 19, wherein a total percentage of the square area of the ground taken up by the columns, relative to the square area of the ground delineated by the edge rows and interior rows, is less than 2%. 21. A method of solar tracking of the solar panels in the elevated solar farm of any of claims 10-12, comprising: rotating the panel connectors around the curvilinear edges of the profiles. 22. The method of claim 21, further comprising rotating the panel connectors around an arc of up to 180˚.