Tilting solar facility

Abstract

A photovoltaic module comprising a set of fixed elements, a rigid body connected to the set of fixed elements so as to be able to swing about a horizontal oscillation axis, one or more bifacial solar panels fixed on the rigid body such that, in the absence of external forces, the rigid body is in an equilibrium position, the rigid body being able to deviate from the equilibrium position under the effect of the wind in order to reduce the windage of the photovoltaic module.

Description

Tilting solar installation Technical field

[0001] The present invention relates to a photovoltaic installation. State of the art

[0002] Photovoltaic installations are already significant, and their number is still growing. While rooftop photovoltaic installations are common, outdoor photovoltaic installations, such as in agricultural or alpine areas, are less common, despite the abundance of potentially usable locations. These installations present special challenges, such as harsh climates, including wind, rain, or snow. In some cases, a reduced visual impact is required or desirable.

[0003] There are also examples of solar installations with vertical photovoltaic elements, either conventional or bifacial. The electrical power generated by these installations is often distributed more evenly throughout the day than that from conventional installations with inclined panels. Aesthetically, vertical systems can be less imposing and more easily accepted.

[0004] Solar installations necessarily have a large collection area, which, together with the wind, generates high aerodynamic forces. This imposes severe mechanical constraints and negatively impacts costs.

[0005] There are known installations with photovoltaic panels suspended vertically from above. Under the action of the wind, the panels assume an inclined position which reduces wind resistance. The angle The tilt angle remains fairly modest in the presence of light or moderate winds and has little effect on energy production. During violent storms, however, the wind can push the panels into a substantially horizontal orientation, thus drastically reducing wind resistance. In systems of this type, the wind can trigger oscillations of the panels, generating sometimes significant dynamic forces.

[0006] Despite all these improvements, known photovoltaic installations can suffer damage when the wind blows with exceptional violence. Brief summary of the invention

[0007] An aim of the present invention is to propose a photovoltaic installation free from the limitations of known products. This is not the only object of the invention which can present several advantages, in combination or alternatively. For example, the photovoltaic system of the invention could, if desired, include features that allow it to be deployed or folded into a shelter depending on the weather conditions. It is also suitable for installations in places that would be difficult to exploit by conventional solar installations, such as orchards, agricultural plots or places frequented by the public or even uneven terrain. Land occupation is reduced.

[0008] According to the invention, these aims are achieved in particular by means of the subject matter of the claims below, in particular by a photovoltaic module comprising a set of fixed elements, a rigid body connected to the set of fixed elements so as to be able to swing around a horizontal oscillation axis, one or more bifacial photovoltaic panels fixed to the rigid body so that, in the absence of external forces, the rigid body assumes an equilibrium position, the rigid body being able to deviate from the equilibrium position by the effect of the wind to reduce the wind resistance of the photovoltaic module. Brief description of the figures

[0009] Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which:

[0010] Figure 1 illustrates an example of a photovoltaic installation according to the invention with a particularly reduced land occupation. The panels installed at height allow access to the ground and its use for other purposes, for example an orchard as illustrated here.

[0011] Figure 2 illustrates a detail of the installation of Figure 1.

[0012] Figure 3 illustrates another example of a photovoltaic installation according to the invention. This variant has a reduced weight and is intended for installation on a flat roof.

[0013] Figure 4 is a conceptual diagram illustrating the effect of wind on the installation of the invention.

[0014] Figures 5 and 6 illustrate an advantageous example of a shock absorber usable in the invention. Example(s) of embodiment of the invention

[0015] The photovoltaic installation illustrated in Figures 1 and 2 is intended to be installed in an agricultural environment and advantageously allows almost unobstructed access to the ground. Each photovoltaic module is arranged horizontally at a sufficient height, as required. The example illustrated concerns an orchard, a vineyard, or agricultural land with tall stem crops, and the free space below the photovoltaic panels is sufficient to allow the development of vegetation and the associated work, such as harvesting, pruning, maintenance, and so on.

[0016] The photovoltaic installation in Figure 1 also allows, if desired, free access to the public, for example to hikers, while protecting the photovoltaic panels from vandalism.

[0017] Two 40 vertical posts fixed in the ground support the installation at the desired height, with a very limited ground footprint. The same support function, however, can be provided by other fixed elements, depending on the situation.

[0018] The photovoltaic installation comprises a rigid body 20 supported by the posts 40 so as to be able to swing around a horizontal oscillation axis 120. In this example, the axis 120 passes through the top of the posts 40 and is materialized by bearings 42, but these are not essential characteristics of the invention.

[0019] The rigid body 20 takes the form, in this exemplary embodiment, of a flat beam comprising a metal frame with vertical crosspieces 24 and, optionally, diagonals 26. Depending on the structure chosen, it can be classified among ladder beams (without diagonals) or lattice beams (with diagonals 26). The photovoltaic panels 30 are installed in the free spaces between the crosspieces 24, substantially in the median plane of the beam, in a vertical position. The diagonals 26 cast a shadow on the active surface of the photovoltaic panels 30; however, the inventors have found that they can be sized so that the reduction in production is small or negligible. Preferably, the diagonals 26 are made with solid cables or tie rods of reduced section. Advantageously, they can be oriented to work mainly in tension, minimizing compression or shear forces.

[0020] The illustration shows a horizontal row of panels. It is understood that, depending on the photovoltaic surface area and free height requirements, the invention could also include photovoltaic modules oriented in “portrait” (the major side vertical instead of horizontal) and / or with several levels of panels.

[0021] Advantageously, the rigid body 20 and the panels 30 mounted therein are normally in their vertical equilibrium position, or very close to it. This position ensures optimal capture of photovoltaic energy when the wind is weak or moderate.

[0022] The angle 0 between the rigid body 20 and the vertical increases with the wind force until reaching, for impetuous winds, values ​​close to 90°. This significantly reduces the wind resistance of the panels 30 and the lateral thrust on the supports 40. Thanks to this characteristic, the system of the invention can withstand severe weather conditions or, for an equal wind speed, be lighter and more economical than an equivalent system with fixed panels.

[0023] Advantageously, the photovoltaic panels 30 may not entirely fill the openings of the rigid body 20. An open space 35 may be present between the upper edge of the panel 30 and the boundary of the rigid body 20. This makes it possible to lengthen the length of the pendulum and increases the natural period of the oscillations. The inventors have determined that a long period is advantageous, in that it makes it possible to control the flapping of the installation when the wind speed is high. The oscillation period can also be increased by adding ballast in the lower half of the rigid body 20, which has the effect of lowering the position of the center of mass, and consequently increasing the length of the equivalent pendulum, or by lowering the oscillation axis 120 towards the middle of the panels, while remaining above, with the effect of reducing the restoring torque of the weight force.

[0024] This concept is illustrated by Figure 4 which is an idealized representation of a photovoltaic installation, seen from the side. The rigid body 30 can swing relative to the horizontal axis 120 under the action of the weight force 200 and the wind thrust 210. In strong winds, the air flow is turbulent and vortices may appear. The rigid body 30 then does not find an equilibrium position but oscillates, sometimes violently, around an angle 0 away from the vertical. These flappings, combined with the elastic oscillations of the beam 20 and the supports 40, may give rise to failures when the wind speed exceeds a critical value. The inventors have determined that this disadvantage is exacerbated when the free oscillation period of the pendulum is short, and less when it is long, for example when the period of free oscillations is one second or more: To> 1 s.

[0025] These unwanted flappings can be controlled by one or more dampers 250 that limit the speed of the oscillations by dissipating energy. Hydraulic dampers or friction systems, magnetic devices in which kinetic energy is dissipated through the phenomenon of eddy currents, or flexible materials capable of damping the oscillations can be used. A single, suitably sized damping system 250 can control the oscillations of the rigid body 20 with a plurality of the photovoltaic panels 30, which is economically advantageous.

[0026] In a preferred embodiment, the damper 250 is configured to perform its function only when the oscillation angle 0 exceeds a predetermined threshold value, corresponding to or below a critical wind speed at which flapping occurs or becomes intolerable. Due to this variable action of the damper, small oscillations below the threshold value are damped little, or not at all. The rigid body 20 can then react immediately to wind gusts by increasing the angle 0 to reduce the thrust 210 and the damper 250 intervenes to reduce the flapping before it becomes excessive.

[0027] It is also possible to provide, if required, a return device 230 tending to bring the rigid body back to the vertical position in collaboration with the force weight 200. This recall can be obtained by springs or other elastic elements, by weights or by any other device.

[0028] Figure 3 shows a variant of the invention intended for installation on a flat roof. The suspension system of the rigid body 20 is equivalent to that of the previous example, but the panel does not allow passage underneath, and the supports 40 have adjustable feet 47 for leveling and installation on the roof of a building. This variant of the invention is not very sensitive to snow conditions and can easily be reconciled with roof vegetation.

[0029] Where possible, it is preferred to install photovoltaic devices on flat roofs by anchoring the feet to ballast plates placed on the roof surface and held in position by their own weight, so as not to touch the waterproofing layers. Compared to rigid vertical or inclined or raised systems, and at the same time as the maximum wind speed expected for the installation site, the module of the invention can be lighter and, above all, less ballasted, because it is able to reduce its wind resistance.

[0030] Figure 5 illustrates, in a simplified manner, a friction damper 250 which can be usefully employed in the invention. It comprises two superimposed friction elements 127 and 129, one of which 127 is fixed and secured to a fixed element, for example the post 40, while the other 129 is secured to the rigid body 20 and follows it in its tilting. The two friction elements 127 and 129 do not touch when the rigid body 20 is vertical in its rest position. They are shaped so that they rub against each other from a determined value of the tilting angle 0> Oo, and generate a friction force which opposes the tilting.

[0031] In the variant illustrated in Figure 5, the friction elements are two sheet metal discs, each comprising two parallel folds forming a flared "U" profile. Instead of folds, discs could be used bent with a curved profile, with an equivalent effect. The circular shape of the friction elements 127 and 129 is also not essential.

[0032] The concavities of the discs are opposite each other and the folds of one of the discs are rotated 90° relative to the folds of the other disc, so that they do not touch each other in the normal configuration. Under normal wind conditions, the rigid body 20 can tilt freely. Beyond a tilting angle Oo, expected when the wind reaches exceptional violence, tilting is possible only due to the elastic deformation of the discs 127 and 129 rubbing against each other, with a damping effect.

[0033] The configuration of Figure 5 is not unique or essential to the operation of the invention. Figure 6 shows a variant in which the concavities of the discs 127 and 129 are oriented in the same direction and their folds are parallel. This variant operates in the same way as that of Figure 5. Many other variants are possible.

[0034] The shock absorber 250 of Figure 5 has the advantage of simple and economical construction, requires no maintenance and can withstand extremely severe weather events. Most of the time, the friction elements never touch each other, the shock absorber remains inactive and does not wear out. The discs 127 and 129 can be made of stainless steel or any other suitable material. Reference numbers used in the figures

[0035] 20 rigid bodies 22 amount 24 crosses 26 diagonal 30 photovoltaic panels 35 free space 25 tilting axis 42 bearing 38 shock absorber 40 post 41 support 120 tilt axis 127 fixed friction disc 129 tilting friction disc 200 force weight 210 wind thrust 230 elastic restoring force 250 shock absorber 9 tilt angle

Claims

Claims 1. Photovoltaic module comprising a set (40) of fixed elements, a rigid body (20) connected to the set of fixed elements so as to be able to swing around a horizontal oscillation axis (120), one or more bifacial photovoltaic panels (30) fixed on the rigid body (20) so that, in the absence of external forces, the rigid body (20) assumes an equilibrium position, the rigid body (20) being able to deviate from the equilibrium position by the effect of the wind to reduce the wind resistance of the photovoltaic module.

2. Photovoltaic module according to the preceding claim, in which the photovoltaic panel (30) or the photovoltaic panels are vertical in the equilibrium position.

3. Photovoltaic module according to one of the preceding claims, in which the rigid body (20) is a planar beam and the photovoltaic panel (30) or the photovoltaic panels lie in the plane of the flat beam.

4. Photovoltaic module according to the preceding claim, the beam being a ladder beam with vertical crosspieces (24) or a lattice beam with vertical crosspieces (24) and diagonals (26).

5. Photovoltaic module according to claim 3, the oscillation axis (120) being aligned with upper edges of a group of photovoltaic panels, or above the photovoltaic panel or panels in the equilibrium position, or between a upper edge of the photovoltaic panel or upper edges of the photovoltaic panels and a center of mass of the rigid support equipped with the photovoltaic panels.

6. Photovoltaic module according to any one of the preceding claims, comprising a return device (230) for returning the rigid body (20) to its equilibrium position.

7. Photovoltaic module according to any one of the preceding claims, comprising a damper (250) for attenuating oscillations of the pendulum movement of the rigid body (20).

8. Photovoltaic module according to the preceding claim, wherein the damper (250) is configured to allow free oscillations of the rigid body (20) when the angle (0) of the rigid support is in a predetermined sector comprising the equilibrium position, and to attenuate the oscillations of the rigid body (20) when the angle of the rigid support relative to the equilibrium position exceeds the limits of the sector.

9. Photovoltaic module according to the preceding claim, the damper (250) being a hydraulic damper, an electrodynamic eddy current damper or a friction damper.

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