EA036603B1 - Solar power plant - Google Patents

Abstract

An offshore photovoltaic power plant (100) comprising a pliable mat (2) configured to be arranged on a surface (33) of a body of water, the mat (2) having a plurality of photovoltaic modules (1) fixed thereon. The photovoltaic modules may be marinized and equipped with a buoyant rigid aluminium structure which prevents mechanical damage to the cells. The rigid backside structure may also serve as an efficient heat sink by direct thermal conduction from the solar cells to the pliable mat. There are also provided a fish farm, an offshore power plant, a method of constructing an offshore photovoltaic power plant and a method of installing a floating photovoltaic power plant.

Description

The present invention relates to the production of renewable energy and, more specifically, to devices and methods related to floating solar power plants.

Background of the invention

Floating photovoltaic (PV) solar power systems are known, although they are not widely used at present. Such systems are usually deployed in calm waters, i.e. on lakes, on reservoirs formed by dams of hydroelectric power plants, on rivers, etc. Some of the challenges associated with floating solar power plants include the effects of waves and currents, the cumbersome and time-consuming deployment of the plant (or its components), and problems with access for maintenance and cleaning of the system (e.g. salt or solids). particles accumulating on the surfaces of the station elements). In addition, currently existing floating solar power systems are also limited by their relatively high cost.

Examples of prior art analogs that may be useful in understanding the background of the invention include US 2012/0242275 A1, which describes a large scale mobile ocean solar power generation plant; US 2015/0162866 A1, which describes a carrier for a solar panel; US 2014/0224165 A1, which describes a device for holding a photovoltaic panel; and KR 1011013316 V and KR 101612832 V, which describe solar cells located on floating devices.

Currently, there are both technical and economic problems associated with floating photovoltaic power plants. Therefore, there is a need for improved systems and methods for generating such renewable energy for a variety of uses and purposes. The present invention is directed to providing improved devices and methods related to floating solar power plants that provide advantages and / or eliminate the existing problems or disadvantages associated with the known systems and methods.

The essence of the invention

In one embodiment, there is provided an coastal photovoltaic power plant comprising a flexible mat adapted to be positioned on the surface of a body of water, the mat having a plurality of photovoltaic modules attached thereto. In the appended claims, additional alternative and / or particularly advantageous embodiments are set forth.

Brief Description of Drawings

Illustrative embodiments of the invention will now be described with reference to the accompanying drawings, in which:

fig. 1 shows a schematic view of a photovoltaic system floating at sea;

fig. 2 shows a photovoltaic module attached to a perforated floating mat;

fig. 3 shows a cross-sectional view of a photovoltaic module with a stiffener containing a heat sink;

fig. 4 shows a sectional view of a photovoltaic module with a corrugated profile cooling stiffener;

fig. 5 shows a cross-sectional view of a mat according to one embodiment;

fig. 6 shows a photovoltaic system according to one embodiment;

fig. 7A-7C show a photovoltaic system in one embodiment;

fig. 8A-8B show a photovoltaic system in one embodiment;

fig. 9 shows a photovoltaic system according to one embodiment;

fig. 10 shows aspects of a photovoltaic module;

fig. 11 shows a sectional view of a photovoltaic module with a corrugated profile cooling stiffener;

fig. 12a and 12B show a photovoltaic system in one embodiment;

FIG. 13 shows a solar power plant according to one embodiment.

Detailed description

Many fixed or floating offshore facilities, such as oil and gas platforms, drilling or processing facilities, require significant amounts of energy to operate. Other energy-consuming facilities include large fish farms or human-inhabited islands that are located away from the electrical grid. The energy demand of these facilities is usually met by diesel or gas turbine generators. Due to the high consumption of energy extracted from fossil fuel sources and the subsequent release of carbon dioxide into the atmosphere, these activities have caused serious controversy among environmentalists and politicians. In addition, the cost of electricity is an important factor taken into account by operators and owners of such installations.

In accordance with the embodiments described herein, there is provided a floating renewable energy generation facility suitable for connection to a conventional land-based electrical network

- 1 036603 by cable, or for autonomous power generation not connected to the power grid. Its embodiments can be used in remote or coastal marine areas or in inland waters and can be designed, for example, to replace fossil-fuel-based generators or power plants and thus reduce CO2 emissions from electricity generation. For example, many densely populated areas, including many metropolitan areas, are located on the coast. In such areas, the available floor space or rooftops suitable for conventional renewable energy sources such as wind and solar power are very limited. In such areas, in accordance with the embodiments described herein, a significant contribution to the production of energy from renewable sources can be made at a moderate cost and with high operational reliability.

Embodiments of this system are suitable for a variety of applications and can be implemented, for example, to replace or meet a significant portion of the daytime energy demand in spring, summer and fall. For example, photovoltaic cells can work well in hybrid power systems, in which flexible, fuel-based generators can easily offset the typical variances that occur when the power output of solar power systems changes due to clouds and the position of the sun. Alternatively, rechargeable batteries can also be used to store energy.

The standard 60- or 72-cell PV module for use in large power plants is not directly designed to withstand the mechanical forces that can occur from shock waves and / or strong gusts of wind at sea. Moreover, these modules usually require solid frames that are securely anchored to the ground. Installation cages can theoretically be located on barges or other floating vessels, but not without significant costs compared to, for example, large-scale land-based installations. The embodiments described herein mitigate such problems associated with conventional technology.

FIG. 1 (not to scale) shows an embodiment comprising interconnected photovoltaic modules 1 mounted on elongated flexible floating mats 2. These mats 2 are attached to buoys 3, which are secured, for example, by chains, polyester or nylon ropes 4, which in turn , anchored to the seabed 5.

FIG. 2 (not to scale) shows a photovoltaic module 1 having a frame 8 with attachment points for attaching it to a floating mat 2 using lugs 9 with brackets 10. The mat 2 can be perforated with holes 30, for example to drain water that collects on the upper side mat 2.

FIG. 3 shows a cross-sectional view of one embodiment of a photovoltaic module 1 suitable for use with the above-described mat 2. The photovoltaic module 1 has a laminate 12 encapsulating silicon-based solar cells 13. Module 1 is built with a lightweight sandwich type composite filler material 6 and heat sinks 7. The heat sinks 7 are positioned to facilitate heat dissipation from the rear of the laminate 12 into the sea.

FIG. 4 shows a cross-sectional view of a second embodiment, in which the heat sink is made of an aluminum profile or corrugated heat sink plates 11 attached to the aluminum frame 8 of the module 1.

The above described embodiments are based on multiple rigid and reinforced photovoltaic modules 1 that are interconnected in strands or dies and mounted on large thin flexible mats or strips 2 that float in the sea. These mats or elongated backing strips 2 are completely flexible, actually follow the movement of sea waves and usually exhibit so-called hydroelastic behavior. Having 2 mats that can cover large areas effectively prevents small waves and splashes. In addition, a plurality of mats 2 can be interconnected.

The mats 2 may or may not have perforations, recesses, one-way valves, pumps, or other devices to allow the removal of accumulated water (such as, for example, rainwater). Alternatively, the mats 2 can be made of mesh, i. E. may have relatively large openings. FIG. 2 shows an example of such perforations 30 made across the mat 2. If desired, the buoyancy of the mats 2 can be designed to hold a thin film of water over some or substantially all of the mat 2. This can be beneficial for cooling the mat 2 itself and / or the photovoltaic modules 1.

The mats 2 can be made from sheet, mesh, fabric, film or board, for example polyethylene, polypropylene, polyurethane, ethyl vinyl acetate (EVA), synthetic rubber, or copolymers, which can be produced in large sections. Alternatively, the fabric can also be multi-layered and / or partially inflated by pockets or elongated tunnels containing gas, low salinity water, floating solids, oils, gels, foams, or other components. This is illustrated schematically in FIG. 5 showing a section through the mat 2 of FIG. 2, with perforations 30 and pockets 31 containing fluid or solid material with a density

- 2 036603 lower than near water, i.e. less than 1 kg / dm ³ . The pockets 31 can be made in the form of elongated tunnels along the length of the mat 2.

The photovoltaic modules 1 are attached to the mats 2, for example, with quick-release carabiners or staples 10, which are attached to the lugs 9, which are securely welded or embedded in the mats 2. Alternative means of fixing can be, for example, belts, sewn-on pockets, welded loops, connecting guides and etc. Many other locking methods can be envisaged within the scope of the present invention.

Advantageously, the design of the frame 8 and module 1 is designed with a triple purpose: firstly, to provide increased rigidity and prevent the destruction of solar cells, secondly, to promote heat dissipation by transferring heat to the colder mat 2 and water, and, finally, to provide an airtight envelope and thereby, optionally, ensuring the buoyancy of the marine module.

The relatively thin silicon-based solar cells in the photovoltaic modules 1 are inherently fragile and prone to fracture. To eliminate the problem of fracture caused by continuous movement and / or shock effects of sea waves, modules 1 can be strengthened. Strengthening can be achieved, for example, by the design of the support frame 8 and / or by adding a stiffening filler material on the rear side 1b of the module 1. The heat sinks 7 and / or the heat sink plates 11 can also be designed to provide structural strength within the module. 1. In this way, a very rigid module 1 can be created, which increases the bending resistance and effective bending radius of laminated solar cells, and thus avoids excessive damage. This hardening can be used, for example, to prevent damage and ensure system reliability in rugged coastal areas. In less challenging locations, such as inland waterways, the reinforcement requirements can be reduced.

Typically, the rear side of the photovoltaic module 1 is open to air circulation in order to avoid thermal insulation, which can cause the solar cells to overheat and lose their electrical efficiency. In one embodiment, this problem is solved in that the rear side 1b is allowed to be in thermal communication (thermal contact) with seawater. This can be achieved by providing an aluminum heat sink 7, 11 attached to the rear side 1b of the module 1 or forming a part thereof. The beneficial effect of water cooling of solar cells itself has long been established and known in the industry. The stiffening filler material, which also acts as the heat sink 6, can also be equipped with cooling channels to allow heat dissipation directly into the water. Such a composite (composite) filler material 6 can also preferably be made of a material with favorable thermal conductivity.

The coastal PV array can be designed with sufficient buoyancy to float with the partially submerged back of the PV modules 1, allowing heat transfer to water. The modules 1 themselves may or may not be floating. The threads 2 of the modules or multiple threads forming an array are fixed to the seabed with anchors 5, chains in combination with a light rope made, for example, of polyester or nylon. Alternative means of mooring are also possible, for example the threads 2 of the modules can be attached to land, for example in applications close to a shore or a dam. To prevent the photovoltaic installation from being pulled by underwater currents and / or by the forces of wave drift, buoys 3 are also installed. Geometry, as well as the number and dimensions of anchors 5 and buoys 3 can be calculated to minimize lateral drift forces. The necessary buoyancy and anchoring points may also be provided by one or more endless (closed) tubular elements that surround the perimeter of the mat. Buoys 3 can also be equipped with appropriate lanterns to indicate the location of the power plant for seafarers.

For easy connection of PV modules 1, quick connectors can be used between the mats 2 and the modules 1, allowing a quick and economical installation by deploying the PV modules 1 attached to flexible mats 2, mat strips or hoses to the surface from a respective vessel or from a land site ( shore), such as a marina. Modules 1 are stackable and can be easily deployed or collapsed in case of extreme weather conditions. The photovoltaic modules 1 are electrically connected to each other using high quality, non-corrosive contacts that can be immersed in water. In addition, the electrical cables may optionally be mechanically attached to the rigid module 1 in order to enhance the strain relief properties beyond that of conventional junction box terminals.

Depending on the size of the PV array array, the number of strings 2, the estimated peak power, etc., the PV system is connected to inverters capable of converting electricity into supply to the intended land or coastal consumer. If inverters and transformers are not installed directly at the offshore end-user facility, they may be sealed and made floating. The latter especially applies to a large-area installation, for example with multiple inverters of solar modules (filaments) connected in series, and also when the power supply to the end user is supplied via the main power cable.

In one embodiment, the pre-assembled strings of modules can be stacked on the deck of ships or barges for easy deployment or folding, for example, for the winter to avoid the most extreme weather and to preserve the system when the power generation capability is reduced due to limited daylight. Alternatively, the PV system can only operate seasonally and can be towed to more favorable waters in winter, such as fjords. In more favorable water areas, these installations are likely to be operated under similar insolation conditions all year round. The horizontal arrangement of the modules 1 when deployed is ideal for near vertical insolation near equatorial waters, but this floating system or the modules themselves can alternatively be manufactured with a constant tilt, for example, 20-30 ° to optimize illumination in the northern or southern hemisphere. The tilt of the modules can also be achieved by raising the top surface of the mat along the lines or ribs provided by tunnels or sections with higher buoyancy. Likewise, grooves or grooves can be provided using denser material such as cables or chains. A slight slope of the modules can sometimes be beneficial to drain rainwater and / or allow the modules to clean naturally.

The photovoltaic system can also be combined with storage batteries and, preferably, can be used in combination with low energy density redox flow cell technology.

Several large massifs will have a calming effect at sea in the vicinity of coastal installations, similar to the effect of oil spills or ice lard on a rough sea. The photovoltaic system, which practically covers the sea surface, will prevent wind-induced wave breaking, ripples and splashing water, while individual PV modules will oscillate slowly under the influence of high water rises. Therefore, the photovoltaic system in accordance with the embodiments described herein can be advantageously combined with other offshore renewable energy generators such as wind turbine generators.

FIG. 6 and 7A-7C show other embodiments of an offshore photovoltaic plant in which the buoyancy element 3 'is an endless (closed) elongated buoyancy element that surrounds the mat 2. FIG. 6 shows, respectively, a top view, a sectional view (left side) and a side view (top in the figure). The buoyancy element 3 'can be substantially circular, as shown in this example, or it can have a different shape. The modules 1 are attached to the mat 2 inside the buoyancy element 3 '. FIG. 7A-7C show an alternative embodiment where the buoyancy element 3 'is large in diameter and more modules 1 are attached to the mat 2. FIG. 7C shows a power plant moored with a four-point mooring device. The presence of a closed elongated buoyancy element 3 ', to which the mat 2 is attached, guarantees the best shape and shape of the mat 2 during operation, and the buoyancy element 3' itself provides protection from wind and / or waves. The installation can optionally be equipped with additional breakwaters located outside the perimeter of the buoyancy element 3 'in order to reduce the impact of waves or flooding of the mat in rough seas.

In one embodiment, there is provided a fish farm comprising an offshore photovoltaic power plant in accordance with any of the above-described embodiments. Providing a fish farm with an offshore photovoltaic power plant provides the advantages that the power generation profile of this power plant will match the power needs of this fish farm: the electricity required to operate fish farm feeding systems is usually consumed during the daytime when photovoltaic generation is highest. ... The same is true for seasonal variations at high latitudes, where, for example, in the summertime, the appetite of salmon is well combined with longer daylight hours and therefore high electricity production.

Providing an offshore photovoltaic power plant with a closed elongated buoyancy member 3 'that surrounds mat 2 makes it easier to moor the power plant in a fish farm, as in many cases the fish farm will have arrangements in place to moor such closed extended buoyancy members.

FIG. 8A and 8B show another embodiment in which the mat 2 in its longitudinal direction 34 comprises sections A, B having alternating buoyancy, and the modules 1 are located between these sections A, B. The upper drawing in each of FIGS. 8A and 8b are side views of mat 2 with modules 1 disposed thereon. Mat 2 floats on the surface 33 of a body of water such as the sea. (The illustration in FIGS. 8A and 8B is schematic for the sake of clarity, and the relative dimensions of the elements may not be representative of the actual system. For example, the thickness of mat 2 may be thinner relative to the size of the modules than that shown in 8A and 8B). The bottom figure in each of FIGS. 8A and 8B show a top view of the mat.

Each section in the first set of sections A has a density that is less than 1 kg / dm ³ and each section in the second set of sections B has a higher density than 1 kg / dm ³ . In order to achieve this, buoyancy elements or pockets 31 of low density material are arranged in each of the sections A in the first set of sections. Additionally (or alternatively), the second set of sections B contains weights 32 located therein or on it. The weight 32 can be material located in the pockets of mat 2, attached to mat 2 by weights, or it can be the material of mat 2 itself, in which sections made with a higher density.

With this arrangement, you can position the modules 1 at an angle to the horizontal, as shown. The modules can be located on one side of the pockets 31 in accordance with the most favorable direction towards the sun, or on both sides, if desired. Tilting the modules to the horizontal can improve the performance and power generation of the modules 1. In addition, it can improve the self-cleaning effect and prevent the accumulation of dirt on the surface of the module 1.

FIG. 9 shows another embodiment in which the heat transfer elements 7 or the heat transfer plates 11 pass through the mat 2 into the sea 33. For this purpose, corresponding holes can be provided in the mat 2. This improves the heat transfer characteristics and hence the cooling of the laminate 12. Such a configuration can be advantageous, for example in warm climates, to enhance the cooling of the modules 1.

FIG. 10 shows another embodiment. In this embodiment, the frame 8 comprises a back plate 15. This back plate 15 is positioned resting on the mat 2 and thermally connected to the aluminum heat transfer elements 7 in the form of seam welded tubes or thin-walled extrusions. As with the embodiment shown in FIG. 3, they extend transversely from the rear plate 15 to the base plate (not visible in FIG. 10, but equivalent to the base plate 14 shown in FIG. 11), which support the laminate 12. The rear plate 15 is attached to the frame 8 along its outer periphery 15 '. Also in the cutout of FIG. 10 shows a fastening element 10 'for attaching the frame 8 to the mat 2. Corresponding fastening elements 10' are also located at other corners of the frame 8. In this embodiment, the heat transfer elements 7 contribute to the added structural strength and rigidity of the frame 8, and the suitable thickness of the heat transfer elements 7 and their arrangement (eg, the pattern of their arrangement seen in FIG. 10) can be chosen so as to achieve the desired / required strength and rigidity.

FIG. 11 shows another embodiment. In this embodiment, the heat transfer plate 11 is in the form of corrugated cooling plates 11 located between the rear plate 15 and the base plate 14. The middle plate 14 is configured to support the laminate 12, and the rear plate 15 is located on the rear side of the frame 8 and is intended to rest on the mat 2. The corrugated cooling plates 11 may be soldered between the plates 14 and 15 or fixed by other means. Also in FIG. 11 illustrates the flux 40 of radiation from the sun. Depending on the weather, geographic location and other factors, it can be, for example, about 1000 W / m ² . Also illustrated is the dissipation of heat 41 from the back plate 15 to the mat 2 and / or to the lower and relatively colder water. This ensures that the solar cells 13 are kept at an acceptably low operating temperature and therefore operate more efficiently (i.e., produce more electrical energy).

FIG. 12A shows a side view of another embodiment in which the pockets 31 are larger and filled with a floating liquid. By making the pockets 31 large, it may, for example, be possible to use a liquid that has only a slightly lower density than the water 33 on which the mat 2 floats. For an offshore installation, for example pockets filled with fresh water can be used. The weights 32 are located between the pockets 31, in this embodiment they are placed on the mat 2 and are not embedded in it. The sinkers 32 between the pockets 31 provide recesses in the mat 2, which can also be used as a drainage channel to drain water from the mat 2. The pockets 31 can, for example, be welded at the seams or sewn onto the material of the mat 2, or the mat 2 with pockets 31 can be made in some other way.

FIG. 12B shows a side view of an alternative embodiment in which the pockets 31 comprise spacers 35. These spacers 35 may be made from the same material as mat 2 or from a different material. The spacers 35 may be positioned to define the shape of at least a portion of the mat 2. In the embodiment shown in FIG. 12B, the spacers advantageously provide a smoother mounting surface for modules 1 on the top side of mat 2.

FIG. 13 illustrates an embodiment of an offshore photovoltaic power plant 100. The power plant 100 is located at a location off-shore near a densely populated area 101 such as a city. Power plant 100 includes a plurality of units such as those shown in FIG. 7A-7C, however, the individual units may be constructed and configured in accordance with any of the above described 5,036603 embodiments. In the embodiment shown in FIG. 13, six blocks are moored near the coast. The power plant 100 is electrically connected to a ground power plant 101 to distribute the generated electricity to the city 101 and / or other ground users via a ground power grid (not shown). Therefore, an embodiment such as that shown in FIG. 13, could, for example, provide significantly more electrical power than would be obtained from terrestrial solar power plants, meaning the usually limited land area near densely populated areas.

Thus, embodiments in accordance with the present invention provide a new and improved coastal photovoltaic power plant and related methods. In accordance with some embodiments, the installation of such a power plant in harsh marine conditions can be accomplished more simply and more safely at a reduced installation cost.

In some embodiments, the problem of power reduction caused by heating of the solar cells can be mitigated and the low operating temperature of the cells can be made possible, which increases their energy efficiency. The influence of waves on the installation, operation and structural integrity of the power plant can also be less than that of the known solutions, which ensures reliable and long-term operation.

Embodiments of the invention may work well in combination with offshore wind farms, where access to and from wind turbines can be difficult in rough seas. In addition, the solar photovoltaic system also works well in conjunction with wind power due to the overlap of weather conditions of power generation, for example, when there is light wind and high solar radiation, and vice versa. For such applications, floating solar PV and offshore wind turbines can share the infrastructure of a land-based power cable. An advantageous effect of an offshore power plant comprising an offshore photovoltaic power plant and at least one offshore wind power generator is that mat 2 has a beneficial effect on the operation of the entire offshore installation and in particular on the wind generators. Calming waves, like the effect of oil on raging water, or calming waves due to, for example, ice oil can have a profound effect on the working environment and / or the overall fatigue life of offshore structures. This extends the life of the wind turbines and reduces the need for inspection and maintenance of the wind turbines, while also making it easier to access the wind turbines.

Claims (13)

CLAIM 1. A floating photovoltaic power plant comprising a flexible mat (2), at least partially made of a floating material and / or having buoyancy elements (3 ', 31) attached or built into it, so that the mat (2) is able to float on surface of the water space, and the mat (2) has a plurality of photovoltaic modules (1) fixed on it, each module (1) lies with its rear side (1b) over the mat (2) and each module (1) contains a solar element (13), while each module (1) is made practically rigid by means of a supporting frame (8) and / or a stiffening element (6, 7, 11, 14, 15). 2. Power plant according to claim 1, in which the module is made substantially rigid by means of a stiffener (6, 7, 11, 14, 15) and the stiffener (6, 7, 11, 15) comprises at least one of: a stiffening material - filler (6), heat dissipating elements (7), heat dissipating plates (11) or base plate (14, 15). 3. A power plant according to any preceding claim, wherein the mat (2) comprises connectors (9) securing the modules (1) to the mat (2). 4. Power plant according to any preceding claim, comprising a heat transfer element (6, 7, 11) located between the laminate (12) and the rear side (1b) of the module (1). 5. Power plant according to claim 4, wherein the heat transfer element (6, 7, 11) comprises corrugated cooling plates (11). 6. Power plant according to claim 5, wherein the module (1) comprises a first plate (14) bonded to the laminate (12) and a second plate (15) forming a rear side (1b) of the module (1), and wherein the corrugated cooling plates (11) are located between the first plate (14) and the second plate (15). 7. A power plant according to any preceding claim, wherein the mat (2) is attached to the buoyancy element (3, 3 '). 8. Power plant according to claim 7, wherein the buoyancy element (3, 3 ') is an endless, elongated buoyancy element that surrounds the mat (2). 9. Power plant according to any one of claims 1 to 7, in which an elongated thread of interconnected modules (1) is fixed on the bendable mat (2). 10. A method of installing a floating photovoltaic power plant, including the step of deploying a floating photovoltaic power plant according to any one of claims 1 to 9 to a body of water. - 6 036603 11. The method of claim 10, wherein the step of deploying the floating photovoltaic power plant is from a ship. 12. The method of claim 11, further comprising transporting the floating photovoltaic power plant coiled and stacked aboard the ship. 13. The method of claim 10, wherein the step of deploying the floating photovoltaic power plant is performed from an onshore site.