NO20230595A1

NO20230595A1 - A solar panel float unit

Info

Publication number: NO20230595A1
Application number: NO20230595A
Authority: NO
Inventors: Geir Grimsrud
Original assignee: Cyprinus As
Priority date: 2023-05-22
Filing date: 2023-05-22
Publication date: 2024-11-25
Also published as: WO2024242567A1

Description

A SOLAR PANEL FLOAT UNIT

Technical Field

[0001] The present invention relates to floating solar power arrangements, and in particular it relates to a float unit for supporting one or more solar panels on a body of water. The present invention is particularly suitable for use in a floating solar power plant as described in NO20220602.

Background Art

[0002] It has been known for some time that photovoltaic solar panels have their greatest power efficiency at relatively cold temperatures and that the efficiency decreases by about 0,3% per degree the temperature of the panel is above -5°C. Land-based solar panels may in hot environments get as hot as 65°C, which will reduce the efficiency noticeably.

[0003] It has therefore been found that placing the solar panels on a body of water, such as a lake or the sea, is a good idea, as large body of water, which rarely will exceed 25°C will cool down the solar panels, in particular if there is direct contact between the water and the solar panel.

[0004] Many water-based solar power plants have been proposed, but most of these are complicated, bulky and do not provide sufficient contact between the water and the panel. The present invention has as its main objectives to provide a float for solar panels that is easy to produce at a low cost, easy to install and maintain and provides efficient water cooling of the panel without subjecting the panel to excessive strain.

[0005] The above objectives are achieved by a float unit as defined in the appended claims.

Summary of invention

[0006] According to the invention, a floating solar power arrangement comprises a float unit having an outer airtight essentially thermoplastic shell and an interior space; the outer shell forming an edge portion extending along the perimeter of the float unit, said edge portion providing buoyancy to the float unit and being partly submerged when the float is deployed on a water surface, and a central portion surrounded by the edge portion, the edge portion having a substantially greater height than the central portion; the float unit having a surface receiving a photovoltaic solar panel thereon.

[0007] The above provides a light float unit with a high buoyancy and small submerged area.

[0008] In a preferred embodiment, the central portion has an underside that is at a higher level that the lowest part of the edge portion and is above the water surface when the float is deployed on the water surface, to create a room between the underside of the central portion and the water surface.This creates an air-filled room between the water surface and the solar panel.

[0009] In a further preferred embodiment, the surface receiving the solar panel is on a ledge outside of the central portion and is arranged at a higher level than the central portion when the float unit is deployed on a water surface, creating a gap between the solar panel and the central portion. This creates an air-filles gap between the solar panel and the float unit.

[0010] In a further preferred embodiment, the central portion has one or more apertures allowing air to flow between the gap and the underside of the central portion. This allows for air exchange between the room next to the water surface and the gap immediately under the solar panel.

[0011] In another preferred embodiment, the edge portion has a raised portion outside of the surface and outside the solar panel. This protects the vulnerable edge of the solar panel.

[0012] In a still further embodiment, the edge portion has at least two depressions providing openings into the gap, allowing air to flow between the gap and the surroundings. This provides an improved air cooling of the solar panel from the underside.

[0013] In an even further preferred embodiment, the edge portion has at least two depressions, which when the float unit is deployed on a water surface providing openings for air to flow into and out of the room between the underside of the central portion and the water surface. This further improves the cooling of the solar panel.

[0014] By arranging the depressions at opposite sides of the float unit, air may flow straight through the air-filled room and gap of the float unit.

[0015] Preferably, the depressions creating openings into the gap are arranged at a 90° angle to the depressions creating openings into the room. Thereby air will flow through at least one of the openings irrespective of the orientation of the float unit with respect to the wind.

[0016] In a further preferred embodiment, the solar panel is fixed to the surface by a clamp attachment, one part of the attachment being moulded into the float unit material. This facilitates and simplifies the attachment and detachment of the solar panel.

[0017] In an alternative embodiment, the solar panel is glued to the surface. This reduces build height and weight and the frame around the solar panel can be dispensed with.

[0018] Further, eyelets are moulded with the float unit material at corners thereof. This provides attachment points for tether lines.

Detailed description of the invention

[0019] Figure 1 shows a float unit according to the invention with a solar panel attached, viewed in isometric view from above,

Figure 2 shows the float unit of the invention with the solar panel detached, viewed in isometric view from above,

Figure 3 shows the float unit of the invention with the solar panel detached, viewed in isometric view from below,

Figure 4 shows the float unit of the invention inn planar view from above,

Figure 5 shows a cross section of the float unit along the line A-A,

Figure 6 shows a cross section of the float unit along the line B-B,

Figure 7 shows a cross section of a part of the float unit along the line E-E,

Figure 8 shows a detailed view G of a corner of the float unit, and

Figure 9 shows a cross section of a part of the float unit along the line H-H.

[0020] When in the following description, the terms above, below, top, bottom, upper, lower or similar are used, this denotes the position of the float unit when it is floating on a body of water.

[0021] Figure 1 shows the float unit 1 with a photovoltaic solar panel 2 attached at an upper side of the float unit 1. The float unit is preferably hollow and made of a thermoplastic material, such as HDPE, PE, PVC or any other thermoplastic which is durable, impact resistant, waterproof and can be recycled. A very convenient way of producing the float unit is through blow moulding, however, rotation moulding, compression moulding, or injection moulding are also conceivable. The float unit can be formed in one part by some of these methods, such as blow moulding or rotation moulding, or in two parts, such as by compression mounding or injection moulding. In the latter case, the two parts will be fused together in a subsequent step, such as by gluing or welding.

[0022] The float unit has an outer shell 13, which surrounds a hollow interior 14, as shown in the cross-sectional views of figures 5 and 6. The interior 14 may be filled with foam, such as polystyrene, but in a preferred embodiment, the interior 14 is airfilled, and the shell 13 is substantially airtight. The plastic material shell may be reinforced by fibreglass, carbon fibres or similar, but it may also be made of a uniform plastic material. The interior space may have reinforcing and stiffening ribs extending from the shell into the interior space.

[0023] The float unit is generally rectangular but may also have other shapes depending on the shape of the solar panel. It has an edge portion 3 extending along the outer perimeter of the float unit 1, with a first height from top to bottom of a few decimetres, such as between 2 and 4 decimetres. The width of the edge portion 3 may be of the same magnitude as the height. As best visible in figure 6, the edge portion 3a is somewhat wider on one side of the float unit 1 than on the opposite side 3b of the float unit 1. This will provide the first side 3a with a higher buoyancy than the opposite side 3b. The result is that the float unit 1 will float at a small angle, such as 3-5° in the water. Hence, the solar panel 2 will also be at an angle. This allows water and debris to run off the solar panel 2.

[0024] Inside of the edge portion 3 is a substantially planar central portion 4 with an upper side 5 and a lower side 6. The central portion 4 has a substantially lower height than the edge portion 3. The edge portion 3 may have a height that is, e.g., between 5 and 10 times the height of the central portion 4. The central portion may be massive, but it is preferred that it comprises an upper shell 15 and a lower shell 16 with an air gap 17 in-between. The air gap 17 is conveniently continuous with the airfilled interior of the edge portion 3.

[0025] A plurality of apertures 7 are formed in the central portion. These may be of different shapes and sizes. The main purpose of the apertures 7 is to let air through for cooling of the solar panel underside. Hence, the apertures will be selected in size and number to allow for sufficient air flow but limit the impact force from water splashing through, so that the water impact will not damage the solar panel 2.

[0026] Between the edge portion 3 and the central portion 4, the float unit 1 has a ledge 8 on which the solar panel 2 will be supported. The ledge 8 is situated somewhat higher than the top surface 5 of the central portion 4 to create a distance from the central portion 4 upper side 5 and the underside of the solar panel 1 and thereby form a gap 22.

[0027] On the outside of the ledge 8, there is a raised portion 9. The raised portion 9 may be a continuation of the edge portion 3 and extends to a height at least at the same level as the upper side of the solar panel 2, but preferably somewhat above. The raised portion 9 ensures that the solar panel 2 is confined to the ledge 8 and protects the edges of the solar panel 2 against impacts. The raised portion 9 may extend continuously around the solar panel 2, but it is of a great advantage that it has interruptions, as shown in figures 1 and 2, which will be explained shortly.

[0028] In the embodiment of figure 1, two interruptions in the form of depressions 10 down to below the level of the ledge 8 are shown, one on each of the longer sides of the float unit 1. In the embodiment of figure 2, there are also interruptions in the form of depressions 11 at the corners of the float unit 1. These are down to the same level as the ledge 8. The flat portions created by the corner depression 11 may be used to arrange fastening features (not shown), that may be moulded integral with the float unit 1, for fastening the solar panel 2 to the float unit 1.

[0029] The depressions 10 at the sides of the float unit creates openings from the outside into the space between the solar panel 2 and the central portion 4. These openings will let air flow along the underside of the solar panel 2 from one side to the other, which will act to cool the solar panel. Occasionally, water may also flow through the openings, when the water surface is disturbed.

[0030] At the underside, the edge portion 8 is interrupted by depressions 12 that may have a height of more than half the total height of the edge portion 8. These depressions create openings extending to above the water surface so that air will flow therethrough into and out of a room 23 between the underside 6 of the central portion and the water surface. The openings by the depressions 12 at the underside are preferably arranged at different sides of the float unit 1 than the openings by the depressions 10 at the upper side, i.e., at 90° of each other. Hence, air will flow in both longitudinal direction and transvers direction through the float unit 1. Due to the apertures 7 in the central portion 4, air will also flow from the underside of the central portion 4 to the upper side.

[0031] The float unit 1 has a buoyancy that is substantially greater than the weight, including the solar panel 2. It is envisaged that the buoyancy is four to eight times the weight. This means that only the lowest portion of the float unit will be below the water, such as between 10 and 20% of the height.

[0032] Since the air flowing through the float unit 1 is close to the water surface, it will have substantially the same temperature as the water at the surface. This means that the air will rarely have a temperature higher than 25-30°C even in the hottest areas of the world. Moreover, the air above water will rarely be stationary but blow along the water surface. In addition, the water surface will also rarely be calm, so that water frequently will splash through the apertures in the central portion 4 and contribute to the cooling of the solar panels.

[0033] If there is no wind, air will still be drawn through the apertures due to temperature differences and thermodynamics. The air drawn into the space between the solar panel 2 and the float unit 1 will be heated by the solar panel 2 and flow out through the opening created by the depressions 10.

[0034] Conveniently, the solar panel 2 is fixed to the float unit 1 in the area of the corner depressions 11 by a fastening assembly 18. Figures 8 and 9 show the details of this fastening arrangement.

[0035] The fastening arrangement 18 comprises a panel lock anchor 19, which can be moulded into the plastic material of the float unit 1 during the moulding of the unit. The anchor has a mould-in part 19a that extends substantially parallel with the surface of the float unit 1 in the area of the corner depression 11. It may have one or more apertures 19b to enhance the anchoring onto the plastic material. It has a free part 19c that extends at a substantially right angle to the surface of the float unit 1 and has a downwardly bent upper part 19d, which forms a downwardly facing U-shaped channel 19e. The U-shaped channel 19e receives an upwardly facing protrusion 20a of a clamp 20. The clamp 20 has a foot 20b that is placed against the surface of the float 1 and a holding part 20c that extends over the edge of frame 21 to which the solar panel proper is attached, to hold this firmly.

[0036] The installation of the clamp 20 can be done by sliding it sideways into interference with the anchor 19. The fit should be tight to prevent the clamp 20 from sliding out of mesh with the anchor. The anchor is conveniently made of metal, such as stainless steel, and the clamp is preferable made of a durable plastic material, such as HDPE.

[0037] An alternative to the above attachment is to attach a frameless solar panel 1, i.e., without a surrounding frame 21, directly to the float unit 1, such as by gluing it directly to the ledge 8. The surface area of the ledge 8 is sufficiently large to provide a strong connection, and the stiffness of the float unit 1 prevents relative movement between the float unit 1 and the solar panel. The direct attachment will reduce both weight and height, as the raised portion 9 can be lower in height.

[0038] The float unit (1) may have channels formed at suitable locations for wires conducting electricity from the solar panel. Conveniently, solar panels on neighbouring float units are coupled together in series or parallel by wires extending from one float to the next. The floats may have integrated clamps to hold the wires.

[0039] At each corner the float unit 1 has eyelets 24 formed by the same moulding step as the unit itself. The eyelets may be reinforced by metal inserts that are placed in the mould before moulding. The eyelets at each of the four corners of the float unit 1 each receive a tethering line that is connected to a mooring system, such as the one described in NO20220602, which is incorporated herein by reference. The float unit 1 will take up the tethering forces through the eyelets. As the float unit is relatively stiff, very little force will be transferred to the solar panel.

[0040] Most of the buoyancy of the float unit is in the edge portion 3. On calm sea only the edge portion will be partly below the water surface, while the central portion 4 will be above the water level. This means that the submerged surface of the float unit 1 will be fairly small. Hence, the possible total amount of fouling from water organisms, e.g., marine organisms in the sea, that may attach to the float will be relatively small. Fouling will add to the weight of the float and cause it to float deeper in the water. A smaller submerged area will increase the time it takes before the fouling will have to be removed to reduce the weight.

[0041] A reduction of the fouling may also be achieved by applying a coating on the submerged part of the float unit 1. Silicon-based paint is an environmentally friendly alternative, which will both prevent fouling and facilitate removal.

[0042] As the float is relatively light in weight, it can easily be detached from the tether lines and lifted out of the water for replacement, maintenance, high-pressure cleaning etc.

Claims

1. A floating solar power arrangement comprising a float unit (1) having an outer airtight essentially thermoplastic shell (13) and an interior space (14); the outer shell (13) forming an edge portion (3) extending along the perimeter of the float unit (1), said edge portion providing buoyancy to the float unit (1) and being partly submerged when the float is deployed on a water surface, and a central portion (4) surrounded by the edge portion (3), the edge portion (3) having a substantially greater height than the central portion (4); the float unit (1) having a surface (8) receiving a photovoltaic solar panel (2) thereon.

2. The solar power arrangement of claim 1, wherein the central portion (4) has an underside (6) that is at a higher level that the lowest part of the edge portion (3) and is above the water surface when the float is deployed on the water surface, to create a room (23) between the underside (6) of the central portion (4) and the water surface.

3. The solar power arrangement of claim 1 or 2, wherein the surface (8) receiving the solar panel (2) is on a ledge (8) outside of the central portion (4) and is arranged at a higher level than the central portion (4) when the float unit (1) is deployed on a water surface, creating a gap (22) between the solar panel (1) and the central portion (4).

4. The solar power arrangement of claim 3, wherein the central portion (4) has one or more apertures allowing air to flow between the gap (22) and the underside (6) of the central portion (4).

5. The solar power arrangement of any of the preceding claims, wherein the edge portion (3) has a raised portion outside of the surface (8) and outside the solar panel (2).

6. The solar power arrangement of claim 2 or 3, wherein the edge portion (3) has at least two depressions (10) providing openings into the gap (22), allowing air to flow between the gap (22) and the surroundings.

7. The solar power arrangement of any of the preceding claims, wherein the edge portion (3) has at least two depressions (12), which when the float unit (1) is deployed on a water surface providing openings for air to flow into and out of the room between the underside (6) of the central portion (4) and the water surface.

8. The solar power arrangement of claim 6 and 7, wherein the depressions (10, 12) are at opposite sides of the float unit (1).

9. The solar power arrangement of claim 8, wherein the depressions creating openings into the gap (22) are arranged at a 90° angle to the depressions creating openings into the room (23).

10. The solar power arrangement of any of the preceding claims, wherein the solar panel (2) is fixed to the surface (8) by a clamping attachment (18), a first part (19) of the attachment (18) being moulded into the float unit material.

11. The solar power arrangement of claim 10, wherein the in-moulded first part (19) of the clamping attachment (18) forms a channel (19e) that is open towards the surface (8) of the float unit (1), and that a second part (20) of the clamping attachment (18) is slidable into the channel (19e) to be held between the channel (19e) and the surface (8), and that the second part has a holding part (20e) that is shaped to clamp down on the edge of the solar panel.

12. The solar power arrangement of any of the preceding claims 1-9, wherein the solar panel is glued to the surface (8).

13. The solar power arrangement of any of the preceding claims, wherein eyelets (24) are moulded with the float unit (1) material at corners thereof.