WO2010086309A1

WO2010086309A1 - Tracking photovoltaic using reflector concentration and reflector movement method

Info

Publication number: WO2010086309A1
Application number: PCT/EP2010/050872
Authority: WO
Inventors: Bruno Bertossi; Gianni Andrea Barnaba
Original assignee: GLOBAL PROCUREMENT Srl
Current assignee: GLOBAL PROCUREMENT Srl
Priority date: 2009-01-27
Filing date: 2010-01-26
Publication date: 2010-08-05
Anticipated expiration: 2011-07-27
Also published as: ITUD20090015A1

Abstract

Tracking photovoltaic plant (10), and relative method, comprising a support frame (11), a plurality of photovoltaic panels (12) mounted in lines or batteries, on the support frame (11), and at least first movement members (13, 113) mounted on the support frame (11) and operatively associated with the photovoltaic panels (12) to determine a first movement of the photovoltaic panels (12) with respect to a first axis of movement ("A"). At least one of the photovoltaic panels (12) comprises, in correspondence with at least one of its sides, at least a reflective element (21) mounted sliding with respect to the photovoltaic panel (12), which reflective element (21) conveys other solar rays toward the photovoltaic panel (12), and other movement members (22, 23, 25) operatively associated with the reflective element (21), in order to determine the linear sliding movement of the reflective element (21) with respect to the photovoltaic panel (12) between a first operating position, in which it protrudes laterally from the bulk of the photovoltaic panel (12), and a second inactive position, translated by sliding with respect to the first operating position, in which it is included in the bulk of the photovoltaic panel (12).

Description

TRACKING PHOTOVOLTAIC USING REFLECTOR CONCENTRATION AND

REFLECTOR MOVEMENT METHOD

* Ψ * * *

FIELD OF THE INVENTION

5 The present invention concerns a tracking photovoltaic plant in which one or more photovoltaic panels are provided in a battery, mounted mobile on a frame, so as to assume always the best condition for exposure to the sun's rays at least depending on the time of day, following the azimuthal angle of the sun, and possibly also depending on the climatic season, following the zenithal angle of0 the sun. In particular, the plant according to the present invention has limited bulk and a much greater photovoltaic efficiency with respect to its actual surface of exposure to the sun.

Here and hereafter in the description, as in the claims, by the term photovoltaic panel we mean one or more photovoltaic modules which, individually or in 5 association, define a photosensitive surface able to capture light radiations.

BACKGROUND OF THE INVENTION

Tracking photovoltaic plants are known, that is, plants in which one or more photovoltaic panels are associated with relative movement actuators.

The movement actuators allow to vary the inclination of the panels at least0 with respect to a first axis so as to optimize the orientation of the panels during the course of the day with respect to the relative position of the sun during the hours of the day.

Tracking photovoltaic plants are also known which, as well as the daily variation in the inclination on the azimuthal angle, also provide an inclination5 with respect to a second axis, to follow the inclination of incidence of the sun's rays as the climatic seasons vary during the course of a solar year with respect to the zenithal angle.

In the current state of the art, essentially two macro-types of tracking photovoltaic plants are known: a first one, with a so-called heavy structure, in0 which the support frames of the panels extend mainly vertically, and a second type, with a so-called light structure, in which the support frames of the panels extend mainly horizontally.

The first macro-type of known plants provides a plurality of individual structures, separated from each other, each of which moves and supports, in a substantially vertical position, a relative plurality of photovoltaic panels.

In this type of known structure, mirrors or other reflective elements may also be provided, attached laterally to the panels, and able to convey other solar rays toward the relative photovoltaic panel, to increase the photovoltaic efficiency thereof.

In order to support the weights of the panels and the forces that are applied on them by atmospheric agents, for example by the wind, these known structures must be very large and attached to the ground in suitable foundations, with a consequent increase in the costs and times of production and installation.

Furthermore, the presence of the mirrors attached to the panels increases the overall surface bulk, causing an increase in the shadow that is projected at the rear.

Therefore, in order to prevent the individual structures of this type of plant from giving shadow to each other, they are suitably distanced in the installation area.

This distance determines a consequent increase in the installation areas which, in most cases, must be specifically dedicated and prepared for this type of application. Consequently, it is also necessary to provide cabling of greater lengths, for connection with the user machines.

The second macro-type of known plants provides a single frame with a mainly horizontal development, on which the photovoltaic panels are mounted selectively directable and positionable, on one or two axes, to follow the position of the sun.

The photovoltaic panels are mounted in lines or batteries on the frame, disposed very close together and compact with each other, so as to optimize the installation spaces and guarantee a sufficient electric power delivered.

The compact positioning of the batteries of photovoltaic panels limits, and even prevents, the possibility of an effective positioning of the mirrors, since these would cause, in particular in their reciprocal positioning in the first and last hours of the day, unproductive shadows between the panels.

Purpose of the present invention is to achieve a tracking photovoltaic plant which, keeping the limited bulk and the versatile installation of plants with a light structure, has the greater photovoltaic efficiency of plants with a heavy structure. The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea. In accordance with the above purpose, a tracking photovoltaic plant according to the present invention comprises a support frame, for example with a mainly horizontal extension, on which a plurality of photovoltaic panels are mounted in lines or batteries.

The plant according to the present invention also comprises at least first movement means operatively associated with the photovoltaic panels, and able to determine a movement of the photovoltaic panels with respect to a first axis of movement, for example to follow the relative movement of the sun during the hours of the day.

According to a variant the photovoltaic plant also comprises second movement means, also operatively associated with the photovoltaic panels, independent with respect to the first movement means and able to determine a movement of the photovoltaic panels with respect to a second axis of movement, different from the first axis of movement, for example to follow the angle of incidence of the sun on the earth's surface as the climatic seasons vary. According to a characteristic feature of the present invention, at least one of the photovoltaic panels comprises, in correspondence with at least one of its sides, at least a reflective element mounted sliding with respect to the photovoltaic panel, and able to convey other solar rays toward the photovoltaic panel. The plant according to the present invention also comprises further movement means operatively associated with the reflective element, to determine the linear and sliding movement of the latter with respect to the photovoltaic panel between a first operating position in which it protrudes laterally from the bulk of the photovoltaic panel and conveys the other solar rays toward the photovoltaic panel, and a second inactive position, translated through sliding with respect to the first, in which it is included in the bulk of the photovoltaic panel, in a hidden condition, with respect to the exposed surface of the photovoltaic panel. In this way, depending on the reciprocal position of the panels, determined by the first and possibly by the second movement means, the reflective element is taken by sliding between its first and second positions so as to increase, in the first position, the photovoltaic efficiency of the panels, and to prevent, in the second position, any shadow zones from forming between the photovoltaic panels due to the reflective elements.

With the present invention it is therefore possible to use reflective elements in a tracking photovoltaic plant of the type with the so-called light structure and the panels disposed in a battery.

The tracking photovoltaic plant according to the present invention can therefore be installed simply and effectively, even in limited or preexisting spaces, for example the floors of buildings, without needing particular foundations or other reinforcement structures.

Indeed, the mainly horizontal structure of the plant according to the present invention has a weight distributed over a wide surface and is subjected only minimally to the action of atmospheric agents such as wind or others.

Furthermore, the reflective elements substantially allow to increase the surface for intercepting the sun's rays of each individual photovoltaic panel, increasing the photovoltaic efficiency thereof. At the same time, since the reflective elements are mobile in a linear and sliding manner, they prevent their shadow from being projected onto the adjacent photovoltaic panels, in particular in the first and/or last hours of the day, when the panels are very inclined with respect to a hypothetical horizontal plane and define a more extensive shadow.

With the present invention it is therefore possible to compact the batteries of photovoltaic panels to the utmost, also obtaining on relatively limited overall installation surfaces a high photovoltaic capacity, thanks to a large number of photovoltaic panels, each having at least one reflective element.

According to a variant, at least two reflective elements are provided for each photovoltaic panel, of which at least one or both are mobile linearly in sliding fashion, and disposed opposite each other with respect to the first axis of movement.

In this variant solution, in some reciprocal positions of the panels, the photovoltaic efficiency of the plant according to the invention is substantially greater than a traditional tracking photovoltaic plant with a light structure.

According to another variant, the plant according to the present invention also comprises at least a command and control unit connected to the first movement means, to the other movement means and/or to the second movement means, in order to coordinate the reciprocal actuation of the three and to optimize the functioning of the plant according to the invention.

According to another variant, the plant according to the invention also comprises sensor means electronically connected to the possible command and control unit, and/or to a user interface.

The sensor means can be provided with one or more position sensors, for example GPS or similar, climatic sensors, such as barometers, wind gauges, angular position sensors, end-of-travel sensors or suchlike, and other sensors which, depending on external factors, command the movement of one, the other or all the movement means of the panels and the reflective elements.

Some possible operating applications of the sensor means can be, for example, to command the movement of the reflective elements between the two positions both according to the hour of the day, and therefore the inclination of the photovoltaic panels, and also the weather conditions, for example to prevent damage to the reflective elements due to hail, or to dispose the photovoltaic panels in a substantially horizontal condition when the sky is cloudy or similar conditions of overcast sky, to recover the reflected light.

According to another variant, in which the sensor means comprise a thermometer to measure the temperature of the photovoltaic panels, when the surface temperature of the photovoltaic panels exceeds a determinate threshold, they are moved with respect to the first and/or the second axis in order to vary the conditions of incidence of the sun's rays and to keep their photovoltaic yield high.

According to another variant, the angle of inclination between the photovoltaic panel and the relative reflective element or elements is fixed and predetermined, and is chosen as desired according to specific design and/or operating requirements.

According to another variant, in correspondence with the sides with respect to which the reflective elements slide linearly, each photovoltaic panel comprises cleaning means, for example blades, disposed in contact with the reflective surface of the reflective element, so as to exploit the linear sliding movement of the latter in order to clean the reflective elements.

According to another variant, the photovoltaic panels are moved all together by the first and second movement means. In particular, all the photovoltaic panels are mounted on a single frame which is in turn moved by the first and second movement means, in a substantially sail- type configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of some preferential forms of embodiment, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 shows a three-dimensional view of a first form of embodiment of a tracking photovoltaic plant according to the present invention;

- fig. 2 shows a front view of the photovoltaic plant in fig. 1 ; - fig. 3 shows a lateral view of the photovoltaic plant in fig. 1 ;

- fig. 4 shows an enlarged detail of fig. 2;

- fig. 5 shows a photovoltaic panel of the plant in fig. 1 in an operating condition;

- fig. 6 shows a detail of fig. 2 in two different operating conditions; - fig. 7 shows a variant of fig. 3;

- fig. 8 shows in sequence some operating conditions in the morning hours of the tracking photovoltaic plant according to the present invention;

- fig. 9 shows in sequence some operating conditions in the afternoon hours of the tracking photovoltaic plant according to the present invention; - fig. 10 shows a front view of a variant of the photovoltaic plant in fig. 1 ;

- fig. 1 1 shows an enlarged detail of fig. 10;

- fig. 12 shows an enlarged detail of fig. 11 ;

- fig. 13 shows a three-dimensional view of a second form of embodiment of a tracking photovoltaic plant according to the present invention.

DETAILED DESCRIPTION OF SOME PREFERENTIAL FORMS OF

EMBODIMENT

With reference to the attached drawings, a tracking photovoltaic plant 10 according to the present invention substantially comprises a frame 1 1 with a mainly horizontal extension, and a plurality of photovoltaic panels 12 disposed in lines or batteries on the frame 1 1.

In this case, each line consists of five photovoltaic panels 12, suitably distanced from each other, and the frame 11 is conformed to support five parallel lines of photovoltaic panels 12. It is clear that, depending on the installation area of the plant 10 according to the invention, the frame 1 1 can be configured on each occasion to support a number of lines and photovoltaic panels 12 per line that is different from five.

According to a variant, the frame 11 is of the modular type, that is, consisting of a plurality of modules, each of which is conformed to support a line of photovoltaic panels 12, or a single photovoltaic panel 12.

In particular, the frame 11 comprises a plurality of uprights and cross pieces connected to each other, to support the photovoltaic panels 12, and is able to be installed on a flat area, also preexistent, such as for example a terraced roof, a flat roofing, or on the ground or elsewhere.

In this case, the photovoltaic panels 12 of each line are mounted mobile with respect to the frame 11, both with respect to a first axis "A", substantially median and longitudinal to the photovoltaic panel 12, and also with respect to a second axis "Z", substantially transverse to the photovoltaic panel 12. In the solutions shown, the second axis "Z" lies along a front edge of the frame 11, in correspondence with relative hinges 19 with which the frame 11 is hinged to the ground.

The movement of the photovoltaic panel 12 with respect to the first axis "A" allows the panel to follow the azimuthal movement of the sun during the hours of the day, whereas the movement of the photovoltaic panel 12 with respect to the second axis "Z" allows the panel to follow the zenithal movement of the sun as the seasons change.

The mobile assembly of each photovoltaic panel 12 with respect to the uprights and cross pieces of the frame 11 can be achieved according to any known assembly technique, for example by means of pins and eyelets, blocks and guides, coordinated profiles for linear sliding, telescopic guides or other mechanical solutions, in any case able to allow the free and independent movement of each photovoltaic panel 12 with respect to the relative first and second axis "A" and "Z".

In the solution shown in figs. 1 to 4, the tracking photovoltaic plant 10 according to the invention also comprises first movement mechanisms 13, in this case one common for all the photovoltaic panels 12 of the same line, and a plurality of second movement mechanisms 15, in this case two for each line of photovoltaic panels 12.

In the solution shown here, the first movement mechanism 13, for each line, comprises a screw-type actuator 16, disposed at the front of the frame 11 and able to move a movement bar 17 in a substantially linear fashion, in one direction and the other.

The movement bar 17 is pivoted to each photovoltaic panel 12 of the same line, so that its movement determines the simultaneous rotation of the photovoltaic panels 12 with respect to the first axis "A".

Advantageously, the assembly of each photovoltaic panel 12 on the frame 1 1 and the movement travel of the screw-type actuator 16 are such that each photovoltaic panel 12 has a range of about 140° around the first axis "A", respectively about 70° on one side and about 70° on the other side, with respect to a hypothetical horizontal plane.

In this case, for each line of photovoltaic panels 12, the second movement mechanism 15 comprises a pantograph actuator 20, attached on one side to the ground (fig. 6) and on the other side to the frame 1 1, so that the latter can be moved under the action of the pantograph actuator 20, rotating with respect to the hinges 19 and thus with respect to the second axis "Z".

In particular, the pantograph actuator 20 is driven by a screw mechanism 18, which moves the levers of the pantograph simultaneously and determines the lifting or lowering thereof. Moreover, due to its constitution, the pantograph actuator 20 not only determines an optimum precision in movement but also a tightening and consolidation of the conditions of inclination achieved. Advantageously, the assembly of each photovoltaic panel 12 on the frame 11 and the movement travel of the pantograph actuator 20 are such that the photovoltaic panels 12 have an operating range of about 50° around the second axis "Z", respectively starting from about 20° to about 70° with respect to a hypothetical vertical plane (fig. 3).

It is clear that the pantograph actuators 20 are conformed so that the photovoltaic panel 12 can also be selectively disposed in a substantially horizontal inactive condition.

According to the variant shown in fig. 7, instead of the pantograph actuators 20 linear actuators 120 are provided, which on one side are pivoted to the ground and on the other side are pivoted to the frame 11. The linear actuators 120, which can be pneumatic, oil-dynamic or other type, have the same functions as the pantograph actuators 20 with regard to the movement of the photovoltaic panels with respect to the second axis "Z". According to the invention, the photovoltaic plant 10 also comprises, for each photovoltaic panel 12, two reflective mirrors 21, able to convey, at least in their operating condition, an additional part of solar rays toward a surface of the photovoltaic panel 12, facing toward the sunlight.

In particular, the two reflective mirrors 21 are mounted mobile linearly through sliding in correspondence with two opposite edges of the photovoltaic panel 12, in a direction substantially parallel to the direction of the first axis "A".

Each reflective mirror 21 advantageously has a predetermined inclination with respect to the plane on which the photovoltaic panel 12 lies, comprised between about 40° and about 70°, advantageously between about 45° and about 60°. The inclination is chosen as a function of the sizes of the reflective mirror 21 and/ or the increase in photovoltaic efficiency desired to be obtained.

Applicant has found that with the present invention it is possible to obtain an increase in photovoltaic efficiency of the panels 12 used by as much as 60%-70% more than the nominal one. For example, using a photovoltaic panel 12 of the mono-crystalline type of about 200 Wp, using the reflective mirrors 21, given the same size of the panel 12, this becomes substantially equivalent to a photovoltaic panel 12 of about 320 Wp, passing from an energy conversion yield of about 17% on average to about 30%.

As we said, the reflective mirrors 21 are mounted mobile linearly and slide along the edges of the photovoltaic panel 12 so as to be able to assume a first operating position, in which they protrude laterally from the photovoltaic panel 12 with said inclination, and a second inactive position, in which they are disposed retracted and comprised in the bulk of the photovoltaic panel 12.

In this case, each reflective mirror 21 is mounted mobile linearly and through sliding with respect to the relative photovoltaic panel 12 by means of a relative track-type movement element 22 (fig. 5), and is guided in its linear sliding movement by means of relative telescopic guides 23. In this way, the movement of the relative track 22 determines the linear sliding of the relative reflective mirror 21 and the progressive extraction of the telescopic guides 23 between said two positions.

In this case, the tracks 22 of two reflective mirrors 21 of the same photovoltaic panel 12 are moved by relative pulleys 24, of which only one is visible in fig. 5, mounted on the photovoltaic panel 12 on the opposite side to the surface facing toward the sunlight.

In particular, the pulleys 24 are alternatively and selectively motorized by means of a common motor 25, also mounted on the photovoltaic panel 12 on the opposite side to the surface facing toward the sunlight.

According to a variant, the motor 25 is configured so as to selectively command in single or simultaneous mode all the pulleys 24 provided on the photovoltaic panels 12 of the same line.

The telescopic guides 23 can have a linear development or can have segments with a diverse inclination, so as to move the reflective mirrors 21 with different inclinations between the first and the second position, so as to optimize the positioning of the latter between the two positions.

According to a variant, the linear movement through sliding of the reflective mirrors 21 occurs by means of worm screw kinematisms, not shown here, commanded by one or more relative torque control electric motors.

According to another variant, the linear movement through sliding of the reflective mirrors 21 can be commanded by means of hydraulic, pneumatic or other actuators. As shown in the enlarged detail in fig. 12, along the sides of the photovoltaic panel 12 with respect to which the reflective mirrors 21 slide, relative cleaning blades 30 are disposed, in pressurized contact with a reflective surface of the reflective mirrors 21. The cleaning blades 30 are made in this case of elastomeric material and comprise a cleaning-reflecting edge which, exploiting the linear sliding movement of the reflective mirror 21 , effects a surface cleaning action on the reflective mirror 21 , removing dust and other impurities that can be deposited on the surface. This solution allows to keep the reflective mirrors 21 automatically clean, optimizing the effectiveness of the reflection.

According to a variant, instead of the cleaning-reflecting edge made of elastomeric material, the cleaning blade 30 can have a brush-like conformation with plastic threads disposed in contact with the surface of the reflective mirror 21.

The photovoltaic plant 10 according to the present invention also comprises a command and control unit 26, which is electronically connected both to the first movement mechanism 13, to the second movement mechanism 15, and also to the motors 25 that drive the tracks 22 of the reflective mirrors 21. In this way, by means of a programmed or selectively programmable operating sequence, the command and control unit 26 determines the movement of the photovoltaic panels 12 with respect to the relative axes "A" and "Z", and the movement of the reflective mirrors 21 between the first and second position.

According to a variant, the command and control unit 26 comprises a user interface unit, not shown, by means of which an operator can carry out controls, maintenance, programming or other of the photovoltaic plant 10, and an interface to configure the photovoltaic field which, according to the parameters of electric power required, the sizes of available surface, the type of commercial panel used, the geographical coordinates of the installation site (longitude, latitude, height above sea level) and the type of possible shading caused by irremovable obstacles, define the number of total photovoltaic panels 12, the number of lines and the distances between the photovoltaic panels 12 and between the lines, to give a technical support to the installer. In a position common for all the photovoltaic panels 12, for example on the frame 11, or in common on the same line of photovoltaic panels, or on each photovoltaic panel 12, a detection station 27 is provided.

The detection station 27 comprises a plurality of sensors, for example position, luminosity, temperature, climatic or other sensors, disposed on the frame 1 1 or on the photovoltaic panels 12 according to the specific detection.

The detection station 27 is electronically associated with the command and control unit 26, so that the signals detected by the various sensors condition the functioning sequence imparted by the command and control unit 26. For example, in particular conditions detected, such as wind above a certain limit, absence of direct irradiance, particular atmospheric events, such as snow, rain, hail or other, irrespective of the position of the sun, the command and control unit 26 commands a substantially horizontal positioning of the photovoltaic panels 12, to prevent damage to them and to optimize the photovoltaic yield.

Advantageously, the photovoltaic plant 10 comprises an energy detector, operatively associated with the photovoltaic panels 12, and able to communicate to the command and control unit 26, instant by instant, the ideal position of the photovoltaic panel 12 in order to optimize the displacement commanded by the latter, and hence to obtain the maximum energy yield.

With reference to the sequence shown in figs. 8 and 9, we shall now explain a possible functioning of the photovoltaic plant 10 according to the present invention in the course of one day.

In the operating position a) in fig. 8, the sun has not yet risen above the horizon and the photovoltaic panels 12 are kept in a substantially horizontal position.

In the operating position b), that is, in the early hours of the day, the azimuthal angle of the sun is very low with respect to the horizontal plane. In this case, the photovoltaic panels 12 of the same line are rotated with respect to their first axis "A, so as to offer their surface to a determinate condition of incidence of the sun's rays such as to not cause shadows on the adjacent modules.

Subsequently, condition c), the azimuthal angle increases and the photovoltaic panels 12 are in a condition substantially perpendicular with the sun's rays. As shown, in this condition c), the first photovoltaic panel 12 starting from the left has a reflective mirror 21 in its first position, to partly increase the reception of the sun's rays, and a second reflective mirror 21 in its second position, so as not to cause any shadow on the adjacent photovoltaic panel 12. The three central photovoltaic panels 12 have both the reflective mirrors 21 in the second condition inasmuch as one mirror 21 would be in the shadow defined by the photovoltaic panel 12 at the extreme left, whereas the other mirror 21 would put the photovoltaic panel 12 at the extreme right in the shade.

The last photovoltaic panel 12 in the line, on the contrary, has the reflective mirrors 21 in a condition substantially opposite the first photovoltaic panel 12 of the line, that is, with the first reflective mirror 21 in the second position and the second reflective mirror 21 in the first position.

In condition d) in fig. 8, the photovoltaic panels 12 have a lower angle of inclination with respect to a horizontal plane, and the intermediate photovoltaic panels 12 have one of their reflective mirrors 21 in their first position, since they are no longer in the cone of shadow defined by the photovoltaic panel 12 at the extreme left.

In this condition d), the last photovoltaic panel 12 of the line has both the reflective mirrors 21 in the first position. In the next condition e), the photovoltaic panels 12 have an even lower angle of inclination with respect to the horizontal plane, and all the photovoltaic panels 12 have both their reflective mirrors 21 in their first position.

In condition f) in fig. 8 and condition g) in fig. 9, the photovoltaic panels 12 are substantially horizontal. In conditions h) to n) in fig. 9, the afternoon dispositions of the photovoltaic panels 12 are shown in sequence. In these conditions, the photovoltaic panels 12 are rotated specularly with respect to said morning positions a)-e), with the difference that the movements of the photovoltaic panels 12 and of the relative reflective mirrors 21 are made in inverse sequence. In the last hours of the day, to prevent shadowing as a consequence to the stopped rotation and the subsequent reduction in the inclination of the sun's rays, the direction of rotation of the photovoltaic panels 12 is inverted (from clockwise to anti-clockwise), in proportion to the angle of solar incidence until a substantially horizontal night-time condition is reached.

With reference to figs. 10 and 11, a variant embodiment of the photovoltaic plant 10 is shown, in which the first movement mechanism, here indicated by the reference number 113, comprises an actuator 116 disposed laterally to the frame 11 and able to move respective movement cables 117, in one direction and the other.

The first movement mechanism 113 also comprises, for each photovoltaic panel 12 of the same line, a movement lever 119, which is centrally constrained to the photovoltaic panel 12 in correspondence with the first axis "A" and has its ends constrained to the movement cables 117.

In this way, the movement of the cables 117 in one direction or the other determines the rotation of the movement lever 119, and hence of the corresponding photovoltaic panel 12, around the first axis "A".

In the embodiment shown in fig. 13, the photovoltaic panels 12 are mounted in a battery on a common platform 31 , also called sail platform, which is in turn supported by a support pedestal 32.

In particular, the support pedestal 32 is fixed to the ground and comprises inside it the first movement mechanism 13 and the second movement mechanism 15, so as to move the platform 31 in coordination with the relative position of the sun.

In this variant of the invention too, according to the invention, the reflective mirrors 21 are mounted sliding linearly in correspondence with the opposite sides of each photovoltaic panel 12, in order to increase the photovoltaic efficiency of the plant 10 according to operating needs and possibilities. It is clear, however, that modifications and/or additions of parts may be made to the photovoltaic plant 10 and method as described heretofore, without departing from the field and scope of the present invention.

For example, it comes within the field of the present invention to provide other reflective mirrors 21 disposed along the short sides of each photovoltaic panel 12. According to a variant, not shown, the first movement mechanism 13 can be independent for each photovoltaic panel 12 and provide electric actuators of a rotary type, or alternative linear mechanisms, or a rack type kinematism or others. According to another variant, the second movement mechanism 15, instead of the actuators 20 for the photovoltaic panels 12 , may provide pairs of actuators for each panel, or also a cam mechanism or other type for a common movement for each line of photovoltaic panels 12. According to another variant, instead of the screw-type actuator 16 a linear actuator is provided, not shown.

It also comes within the field of the present invention to provide that, instead of the tracks 22 and the telescopic guides 23, the reflective mirrors 21 can be suitably pivoted along the edges of the photovoltaic panels 12, so as to be able to be selectively rotated between one of their two positions and the other.

It is also clear that, although the present invention has been described with reference to specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of tracking photovoltaic plant and relative movement method, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.

Claims

1. Tracking photovoltaic plant comprising a support frame (11), a plurality of photovoltaic panels (12) mounted in lines or batteries, on said support frame (11), and at least first movement means (13, 113) mounted on said support frame (11), operatively associated with said photovoltaic panels (12), and able to determine a first movement of said photovoltaic panels (12) with respect to a first axis of movement ("A"), characterized in that at least one of said photovoltaic panels (12) comprises, in correspondence with at least one of its sides, at least a reflective element (21) mounted sliding with respect to said photovoltaic panel (12) and able to convey other solar rays toward said photovoltaic panel (12), and other movement means (22, 23, 25) operatively associated with said reflective element (21), in order to determine the linear sliding movement of said reflective element (21) with respect to said photovoltaic panel (12) between a first operating position, in which it protrudes laterally from the bulk of said photovoltaic panel (12), and a second inactive position, translated by sliding with respect to said first operating position, in which it is included in the bulk of said photovoltaic panel (12).

2. Plant as in claim 1, characterized in that it comprises second movement means (15) mounted on said support frame (11), operatively associated with each photovoltaic panel (12), and able to determine a second movement of said photovoltaic panel (12) with respect to a second axis of movement ("Z"), different from said first axis of movement ("A").

3. Plant as in claim 1 or 2, characterized in that it comprises at least two reflective elements (21) for each photovoltaic panel (12), of which at least one is linearly mobile by sliding.

4. Plant as in claim 3, characterized in that said two reflective elements (21) are disposed opposite each other with respect to said first axis of movement ("A").

5. Plant as in any claim hereinbefore, characterized in that it also comprises at least a command and control unit (26) connected to said first movement means (13, 113), to said other movement means (22, 23, 25), and/or to said second movement means (15), in order to coordinate the reciprocal actuation.

6. Plant as in claim 5, characterized in that it also comprises sensor means (27) electronically connected to said command and control unit (26) and able to condition, depending on determinate parameters and detected data, the actuation of said first movement means (13,113), of said other movement means (22, 23, 25) and/or of said second movement means (15).

7. Plant as in claim 6, characterized in that said sensor means (27) comprise one or more position, meteorological and/or temperature sensors.

8. Plant as in any claim hereinbefore, characterized in that said first movement means (13) comprise at least a screw type actuator (16) able to move a movement bar (17) constrained to each photovoltaic panel (12) of the same line or battery.

9. Plant as in any claim hereinbefore, characterized in that said first movement means (113) comprise at least an actuator (116) able to move respective movement cables (117) connected by means of relative movement levers (119) to each photovoltaic panel (12) of the same line or battery.

10. Plant as in any claim hereinbefore, characterized in that said second movement means (15) comprise at least a pantograph actuator (20).

11. Plant as in any claim hereinbefore, characterized in that the angle of incidence between the photovoltaic panel (12) and the relative reflective element or elements (21 ) is fixed and predetermined.

12. Plant as in any claim hereinbefore, characterized in that each photovoltaic panel (12) comprises cleaning means (30) provided in correspondence with the sides with respect to which the reflective elements (21) slide linearly and disposed in contact with the reflective surface of the relative reflective element (21), so as to carry out the cleaning of said reflective surface during the linear sliding movement of said reflective element (21) with respect to the photovoltaic panel (12) between the first operating position and the second inactive position.

13. Plant as in claim 1, characterized in that it comprises a single frame (31) on which the photovoltaic panels (12) are mounted, which frame (31) is moved at least by the first movement means (13) so as to determine the simultaneous movement of all said photovoltaic panels (12) with respect to the first axis of movement ("A").

14. Movement method for a tracking photovoltaic plant comprising a support frame (11) which extends mainly horizontally, a plurality of photovoltaic panels (12) mounted in lines or batteries on said support frame (11), said method comprising at least a first movement of said photovoltaic panel (12) with respect to a first axis of movement ("A"), by means of first movement means (13, 1 13) mounted on said support frame (11) and operatively associated with each photovoltaic panel (12), characterized in that at least during said first movement it provides a movement of at least one reflective element (21) provided in correspondence with at least one side of at least one of said photovoltaic panels (12), between a first operating position, in which it protrudes laterally from the bulk of said photovoltaic panel (12), in order to convey other solar rays toward said photovoltaic panel (12), and a second inactive position, in which it is included in the bulk of said photovoltaic panel (12), by means of third movement means (22, 23, 25) operatively associated with said reflective element (21).

15. Method as in claim 14, characterized in that it comprises a second movement of said photovoltaic panel (12) with respect to a second axis of movement ("Z"), different from said first axis of movement ("A"), by means of second movement means (15) mounted on said support frame (11) and operatively associated with each photovoltaic panel (12).