Technical Field

[0001] The present invention relates to floating and moored installations for fastening photovoltaic modules generating photovoltaic energy at a predetermined area.

Background Art

[0002] Floating photovoltaic installations are preferably located at ocean locations with the most sun days per year and at remote sites well away from known shipping lanes. However, said areas are also warm ocean waters which are typically near the equator. Waters at or near the equator are also considered to be a hotspot for frequently occurring tropical cyclones, such as hurricanes and typhoons. It is therefore essential that such installations are well built so to withstand the powerful forces of Mother nature.

[0003] WO2021035259A1 describes a system for a floating grid acting as a support structure for floating solar panels. The system does not disclose anything wherein it can withstand severe ocean conditions and safeguarding the structural integrity of said solar panels from said conditions.

[0004] WO2017023536A1 is a prior art which discloses a similar floating support grid for photovoltaic panels, wherein the grid is made from a combination of polymer tubes and metal frames. The tubes provide buoyancy for the structure and the solar panels are attached to stiff metal rods, which in turn are attached to the tubes. The frame-like structure is moored through mooring lines attached to two or more of the comers of the frame.

[0005] The prior art creates a rather stiff structure where all forces have to be taken up by the frame. Both the tubes and the metal rods have to resist relative movement, which otherwise would be transferred to the panels. If any part of the structure is damaged, the panels and structure in the vicinity of the damage will be subjected to substantially higher strains. Consequently, the prior art does not describe a sufficiently robust technical solution which can withstand severe ocean conditions. [0006] An alternative prior art, which discloses a floating grid system, is W02007081221 describing a floating grid system for mooring mobile offshore units, such as drill rigs and FPSOs, located at a predetermined area of operation. However, such solution is mainly made for mooring and containing large vessels. The grid is arranged as a “false seabed” some distance below the water surface. Said large vessels are capable of withstanding harsh ocean conditions on their own and said floating grid system is arranged well below the wave affected water. It does not provide any protection against large waves and storms other than mooring.

Summary of invention

[0007] It is an object of the present invention provide an arrangement for securing photovoltaic modules in a floating grid enclosure, which can withstand severe ocean conditions.

[0008] It also an object of the present invention to provide a floating photovoltaic (PV) fastening arrangement for fastening a plurality of floating PV modules generating electric power comprising; a primary buoyant assembly for providing an enclosure for and means for anchoring said plurality of PV modules, a plurality of longitudinal flexible lines, a plurality of transverse flexible lines, wherein each end of said lines are fastened and tensioned to predetermined fastening points on said primary buoyant assembly forming a grid within said assembly, a plurality of fastening units for locking intersecting points between said longitudinal and transverse lines of said grid, wherein said plurality of fastening units also function as means for anchoring said plurality of PV modules; a plurality of mooring lines and a plurality of anchors, wherein one end of each mooring line is connected to said primary buoyant assembly and the other end of the mooring line is connected to an anchor on the ocean floor.

[0009] In a preferred embodiment the present invention the primary buoyant assembly comprise a first, second, third and fourth oblong buoyancy elements forming a rectangular frame.

[0010] In a further preferred embodiment, the oblong buoyancy elements are not directly fastened to one another but interconnected through the longitudinal and transverse flexible lines. [0011 ] According to a further embodiment, each oblong buoyancy elements have a predetermined number of predetermined fastening points.

[0012] In an alternative embodiment, said first, second, third and fourth oblong buoyancy elements are formed as one part.

[0013] In a further alternative embodiment, said primary buoyant assembly forms a buoyant circular frame.

[0014] In a preferred embodiment, each fastening unit comprise a first internal coupler unit, a second coupler unit, a base for holding said first and second coupler unit with a threaded section and a lid to be threaded on said base for locking the fastening unit.

[0015] in a further embodiment, said plurality of mooring lines includes mooring bridles, wherein each said mooring bridle is fastened to at least two or more predetermined fastening points and an anchor.

Brief description of drawings

[0016] Figure 1 illustrates a perspective overview of an embodiment of the invention,

[0017] Figure 2 illustrates an embodiment of the invention without photovoltaic (PV) modules,

[0018] Figure 3 illustrates an embodiment of the invention without PV modules and mooring,

[0019] Figure 4 illustrates a detailed view for an embodiment for fastening a tension line to a buoyancy module,

[0020] Figure 5 illustrates another embodiment of the invention utilizing mooring bridles,

[0021 ] Figure 6 illustrates another embodiment of the invention utilizing mooring bridles and additional buoyancy units,

[0022] Figure 7 illustrates another embodiment of the invention wherein the buoyancy module is circular,

[0023] Figure 8 illustrates another embodiment of the invention wherein the circular buoyancy module utilizes mooring bridles, [0024] Figure 9 illustrates a detailed view of an embodiment of a fastening unit,

[0025] Figure 10 illustrates a detailed view of PV modules connected to fastening points in a floating mooring grid.

Detailed description of the invention

[0026] Figure 1 to figure 3 shows a floating photovoltaic (PV) fastening arrangement

1, or henceforth, a floating mooring grid 1 intended to function as a robust and stable anchoring area at predetermined location for a plurality of floating PV modules 2. The floating mooring grid 1 comprises a primary buoyant assembly 3, which can comprise a first, second, third and fourth oblong buoyancy elements 3a, 3b, 3c, 3d, forming a buoyant rectangular frame, surrounding said plurality of floating photovoltaic modules

2. In an embodiment said arrangement the oblong buoyancy elements 3a, 3b, 3c, 3d can be tubes made of polymer materials or metals. In the embodiment shown in figures 1-3, the oblong buoyancy elements are not directly coupled to each other at the corner of the frame but held at a short distance from each other. Hence the tubes constituting the buoyancy elements are free to move somewhat with respect to each other.

[0027] Said floating mooring grid 1 further comprise of a plurality of flexible longitudinal lines 4 and a plurality of flexible transverse lines 5, wherein a first end of each longitudinal line 4 is fastened to the first oblong buoyancy element 3a and the opposite second end of each longitudinal line 4 is fastened the third oblong buoyancy element 3c.A first end of each of the transverse lines 5 is fastened to the second oblong buoyancy element 3b and the opposite second end of each transverse line 5 is fastened the fourth oblong buoyancy element 3d. Said plurality of longitudinal lines 4 and a plurality of transverse lines 5 are provided in tension in order to maintain the shape and structural integrity of said floating mooring grid 1, as will be explained below. The lines are preferably fastened equidistantly along the tubes. The flexible lines are preferably made of rope, such as a synthetic fibre robe, e.g., nylon, polypropylene, polyester, Kevlar, HMPE or other materials known to have long durability in marine environments.

[0028] As will be explained in detail below, the tubes 3a, 3b, 3c and 3d are moored to provide tension to the flexible lines 4, 5, so that the flexible lines 4, 5 are taut between the tubes. [0029] Figure 4 shows a preferred embodiment wherein said pluralities of longitudinal and transverse lines 4, 5 are tied to a predetermined fastening point 50 on said oblong buoyancy elements 3a, 3b, 3c, 3d, providing tension to said pluralities of longitudinal and transverse lines 4, 5. The tying of the line can be done by laying the line one or more times around the tube and attaching the end of the line to the part extending between the tubes, As shown in figure 4. The fastening point 50 may just be a uniform surface of the tube, but it may also comprise a groove around the tube or elevations between which it line is placed.

[0030] At each intersecting point 10’ between the longitudinal and transverse lines 4, 5, said longitudinal and transverse lines 4, 5 are locked to each other by a fastening unit 6, as shown in figure 10. The fastening unit 6 resists longitudinal and transverse movements of said longitudinal and transverse lines 4, 5. The combination of the pluralities of longitudinal and transverse lines 4, 5 and fastening units 6 form a plurality of rectangle enclosures or spaces 40 (se figure 3) within the primary buoyant assembly 3, in effect forming the grid 10 of the floating mooring grid 1. Each rectangle enclosure 40 comprise two sections of longitudinal lines 4, two sections of transverse lines 5 and four fastening units 6. Each rectangle enclosure 40 is intended to accomodate a floating photovoltaic module 2, wherein said floating photovoltaic module 2 can be moored or fastened by at least tethering lines 2a, preferably four tethering lines 2a, to the four adjacent fastening units 6 of the rectangle enclosure 40.

[0031] As shown in figure 9, an embodiment the fastening unit 6 include the following components; a first internal coupler unit 6a, a second coupler unit 6b, a base 6c for holding said first and second coupler unit 6a, 6b with a threaded section and a lid 6d to be threaded on said base 6c for locking itself and said components 6a, 6b, 6c on to an intersection 10’ of the longitudinal and transverse lines 4, 5. The first and second coupler unit 6a, 6b and base 6c are adapted to provide a fit for the intersection 10’ of the longitudinal and transverse lines 4, 5.

[0032] Said components 6a, 6b, 6c, 6d of the fastening unit 6 can be made of buoyant material which may prove useful during installation or maintenance when on site in the open waters. The fastening unit 6 is intended to provide a simple and straightforward means of locking an intersection 10’ of said longitudinal and transverse lines 4, 5. [0033] Although the fastening units 6 are designed to restrict longitudinal movement of the lines at their intersection, the fastening units may be designed to allow longitudinal movement if a tension in a line exceeds a predetermined value. The predetermined value is lower than the rupture strength of the line. This way the structure can withstand higher forces without being broke apart.

[0034] If a structure has been subjected to forces that have caused any lines to slip relative to the fastening units, the units may later be disengaged, the ropes moved to the right position and the fastening units attached again at the right location.

[0035] An embodiment of the mooring configuration is shown in figures 1 and 2, where each mooring line 7 is fastened to the floating mooring grid 1 at a predetermined fastening point 50, which may be at the same or a different place than the fastening point of the flexible lines 4, 5, and the opposite end of said mooring line 7 is connected to an anchor 8 located on the ocean floor as shown in figure 1 and 2.

[0036] As shown in figure 5, an alternative embodiment of the mooring configuration includes mooring bridles 7a, wherein a mooring bridle 7a is connected to at least two or more predetermined fastening points 50 and an anchor 8. The mooring bridles 7a can also include additional buoyancy elements 30, as shown in figure 6, in order to provide additional buoyancy to the floating mooring grid 1 and the mooring lines 7 or mooring bridles 7a.

[0037] The mooring tension from the mooring lines 7 is selected to provide a tension of the flexible lines 4, 5 within a predetermined range. The tension may be adjusted by adjusting the length of the mooring lines 7 or repositioning the anchors 8.

[0038] In an alternative embodiment of the invention the primary buoyant assembly 3 can be a buoyant circular frame 3f as shown in figures 7 and 8. Said circular frame 3f can be one tube or several compounded tubes made of polymer materials or metals. Said pluralities of longitudinal and transverse lines 4, 5 are also tied to a predetermined fastening point 50 on said circular frame 3f providing tension to said pluralities of longitudinal and transverse lines 4, 5.

[0039] In the embodiments of figures 7 and 8, a pre-tensioning of the lines 4, 5 may be done when the flexible lines 4,5 are attached to the circular frame 3f. The mooring lines 7 may influence on the tension of the lines 4, 5 by deforming the circular frame 3f, but in that case, the lines 4,5 extending, e.g. in the longitudinal direction, may get an increased tension while the lines 4, 5 extending transverse of the longitudinal lines

4, 5 may get a reduced tension. It is therefore conceivable to have a means for transferring the mooring tension from the mooring lines 7, 7a to each flexible line 4, 5. This may be by providing a direct coupling 50a between a mooring line 7, 7a and a flexible line 4, 5, such as providing a mechanism 50a in the circular frame 3f allowing the flexible lines 4, 5 and mooring lines 7, 7a to move transverse to the circular frame 3f. This may be a sheave 50a over which a continuous line can extend or a coupling piece 50a to which the mooring line and the flexible line are attached, and which is allowed to move relative to the circular frame.

[0040] Another alternative is to provide the circular frame 3f with joints 300, as shown in figure 8, figure 11 and figure 12, such as one or more telescopic joints 300 that allow for an increase or reduction of the circumference of the circular frame 3f.

[0041] The oblong buoyancy elements 3a, 3b, 3c, 3d can also have at least one or more telescopic joints 300 that would allow for an increase or reduction of their respective length for achieving a preferred tension in the mooring lines 7, 7a and the flexible lines 4, 5.