FR2465968A1 - SYSTEM FOR CAPTURING SOLAR ENERGY - Google Patents

Abstract

A. SOLAR ENERGY CAPTURE SYSTEM. B. IT INCLUDES AT LEAST ONE SOLAR ENERGY CONCENTRATOR 12 INCLUDING 1 A ROTARY HOLLOW TUBE 38 INCLUDING A LENS 40 ALLOWING AT LEAST PART OF THE SOLAR RADIATION 2 OF THE SOLAR ENERGY CONVERSION MEANS AVAILABLE IN THE TUBE AND 3 A PAIR OF 68 END ELEMENTS FIXED AT THE TUBE ENDS; A TUBE SUPPORT ASSEMBLY 10 ALLOWING THE TUBE TO ROTATE, AT LEAST ONE END ELEMENT CONSISTING OF A PULLEY; AND ROTATION DRIVE MEANS INCLUDING A CABLE COOPERATING WITH THE PULLEY TO ROTATE THE TUBE. C. APPLICATION: CAPTURE OF SOLAR ENERGY.

Description

O1. The present invention relates to energy capture systems

  solar energy and relates in particular to a system of

  the improved solar energy able to follow the sun.

  Due to the energy crisis, many solar energy capture systems have been proposed to track the sun. For example, reference can be made to US Pat. No. 4,069,812

  issued on behalf of O'Neill on January 24, 1978, and the US patent

  No. 4,144,095 issued to Mlavsky on March 13, 1979.

  Some of these systems, such as that described in the patent

  O'Neill include assemblies or units of

  taking a trough concentrator and a lens taken

  mounted on the concentrator, the lens and the concentra-

  Both of these serve to concentrate solar energy on the set of solar cells disposed near the bottom of the concentrator. When the trough concentrator

  has a special geometric configuration such as the

  As shown in the O'Neill patent, the rotary assembly includes edges which are likely to catch on the structures in the form of the trapezoidal cross section.

  immediate neighborhood. For example, when considering

  to use such catchments in arid climates or

  cold, the presence of sand or snow can

  sets due to the presence of these edges. In addition, because of the large size of each assembly, although the lens can be mounted tightly on the trough concentrator, it is possible that these seals are not sufficient to seal tightly.

  each set to make it possible to empty each

  appears or fill it with an inert gas in order to protect

the set of solar cells.

  Although it has been proposed to collect

  rotary solar energy with geometric

  Cylindrical outer layers have been found to have one or more disadvantages. For example, the assembly shown in the Mlavsky patent comprises a cylindrical shell

  outside and a set of solar cells arranged at the in-

  inside the envelope. The envelope is relatively small 02. (having approximately the size of the commercially available fluorescent lamp envelopes), which makes it possible to

  empty the envelope or fill it with an inert gas

  te and seal it tightly to protect the solar cell assembly. In order to ensure a good seal of

  envelope, it has relatively small dimensions

  compared to the dimensions of the concentrator-shaped

  trough of the system shown in the O'Neill patent. As a result

  there is a corresponding reduction in concentration

  (even when reflectors are provided inside the enve-

  loppes), in particular because one does not use lens of concentration. In addition, there are problems with the structures

  specific support systems for various collection systems, the

  of these structures that can cast shadows on

  rotating assemblies at various times during the day,

  which is obviously undesirable.

  Accordingly, an object of the present invention is to

  a sophisticated solar energy capture system that solves or alleviates

  associated with the systems of the prior art.

  Another object of the present invention is to provide a

  advanced solar energy capture system includes

  one or more rotating capture assemblies and an improved tracking mechanism - ensuring the rotation of the units. Another object of the present invention is to provide an improved solar energy sensing system comprising one or more rotary sensing assemblies, each of which has a cylindrical cross-sectional configuration and is constructed to form part of the tracking mechanism

  Another object of the present invention is to realize

  a solar energy capture system capable of ensuring

  relatively high concentrations of solar energy

  re on a set of solar cells and to ensure at the same

  time to all a hermetically sealed environment.

  Another object of the present invention is to provide a solar energy sensing system comprising an improved support structure capable of rotatably supporting the

  individual rotating sets of solar energy capture.

  In order to achieve these and other objects, the present invention is directed to a solar energy capture system comprising

  in combination, at least one concentration unit of the

  solar energy, a support system designed to support

  rotation of said unit and rotation means for providing

  rotate the unit. The concentration unit or concentrator comprises (1) an elongated hollow tube having an axis of rotation in its elongate direction and comprising a lens allowing at least a portion of at least some of the incident solar energy to pass and extending around a

  part of the tube and constituting at least part of the tube of

  concentrating the solar energy therethrough, (2) means for converting solar energy disposed within the tube relative to said lens so that,

  when the tube is in a predetermined angular position

  minus the sun around the axis of rotation, the energy

  solar energy transmitted by the lens is concentrated on the means of conversion of solar energy, and (3) a pair of end members respectively fixed on the ends

  opposite of the tube. At least one of the end members is

  designed to act as a pulley. The support assembly supports the tube so that the tube is supported rotating about the axis of rotation. The rotation means comprise cable traction means and a flexible cable able to be moved by the cable traction means and cooperating with the pulley-shaped end member to rotate the tube relative to the assembly. of support around the axis of rotation so that the tube can be held at the position

  predetermined angle as the position of the sun changes

  ge. In the preferred system, the support assembly is constructed so that (1) the support assembly does not cast shadow on the unit of concentration while the unit is tracking the sun and (2) constitutes an envelope of protection of the means

cable traction.

  An embodiment of the present invention is hereinafter described by way of example with reference to the accompanying drawings in which:

  FIG. 1 is a perspective view of the embodiment of

  preferred embodiment of the solar energy capture system according to the present invention; FIG. 2 is an exploded perspective view of the concentration unit of the embodiment shown in FIG. 1; FIG. 3 is a partial cross-sectional side view of the concentration unit rotatably supported by the support assembly; Fig. 4 is a cross-sectional view along the line 4-4 of Fig. 3 of the concentration unit; Figure 5 is a perspective view of the preferred cable traction means for moving the cable of the embodiment shown in Figure 1;

  FIG. 6 is a diagram of the control circuit enabling

  both to control the rotation of the unit of concentration; FIG. 7 represents an alternative embodiment of the concentration unit of the embodiment shown in FIG. 1;

  FIG. 8 represents a second variant of embodiment

  tion of the concentration unit of the embodiment

shown in Figure 1; and

  FIG. 9 represents a third variant of embodiment

  the concentration unit of the embodiment

shown in Figure 1.

  Referring now to the figures, in which the same reference numerals denote the same elements and we see in FIG. 1 the preferred collection assembly of solar energy 8 which generally comprises a support assembly 10 making it possible to withstand the rotating at least one and preferably a plurality of solar energy concentration units 12, each containing solar energy conversion means comprising a set of solar cell groups 14

  (best shown in Figure 3). Units are trained

05.

  rotated by drive means comprising a cable

  16 and cable traction means 18.

  The support assembly 10 includes a base 20, the support frame of the unit 22, and front and rear legs 24 and 26 respectively carrying the frame 22 on the base 20. The base 20 provides a substantially flat support. The frame 22 comprises a front horizontal member 28 carried by the front legs 24 and comprising spaced tubular bearing supports 30,

  each of which rotates one end of a unit corresponding to

  12. The frame 22 further comprises a horizontal element

  rear support 32 carried by the rear legs 36 and comprising spaced bearing supports 34, each of which rotates the opposite end of each of the units 12. The bearing supports 30 and 34 are preferably positioned relative to each other. the other so that the axes of rotation of the units 12 are all perpendicular to the two horizontal elements

  front and rear 28 and 32, respectively, and are significantly

  in the same plane. The frame 22 further comprises lateral elements 36 connecting the horizontal elements before and

  28 and 32. The side members 36 are disposed beyond

  below the plane defined by the axes of rotation of the unit 12 so that, when the assembly 8 is correctly positioned relative to the path of the sun, (that is to say that in the northern latitudes the front of the 8, defined by the front feet 24, stands in front of the south so that the units 12 turn from east to west to follow the sun), the side elements 36 do not cast any shadow on the

  units 12. The entire support assembly 10 is preferably

  made from a hollow tube of a suitable material

  light weight such as polyvinyl chloride, or a resistant material such as steel. The front feet 24 are shorter than the rear legs 26 so that the units 12

  are inclined towards the sun. Each of the rear legs

  re 26 preferably, but not necessarily, includes two or more telescopic members that can be locked in two or more positions by appropriate means such as locking members 37 (only one of which is 06. shown in FIG. 1) so that the angle of inclination of the units 12 can be adjusted periodically according to the seasons to take into account, if necessary, the variation of altitude

of the sun.

  Each concentration unit 12, shown in FIG. 1 and in more detail in FIGS. 2-5, comprises an elongate hollow tube 38, preferably of a straight circular cylindrical configuration and open at both ends. includes a lens system letting through

  partially at least part of the solar radiation

  tooth and extending around at least a portion of the tube 38 to concentrate the solar radiation transmitted through

  it. The lens preferably consists of a lens

  the prismatic 40 having a convex cylindrical outer surface and an inner surface adapted to define an elongate linear lens segment 42 along the center of the lens and linear prismatic facets 44 extending from each side of the central lens segment 42 towards the edges of the prismatic lens 40. The lens 40 is designed so that when the central segment of the lens

  is directly in front of the sun, the solar radiation

  the incident is concentrated on the entire group of

  solar 14, which will become clear later. The entire tube 38, including the prismatic lens 40, may be made in one piece by extrusion, for example, from a suitable thermoplastic material or, alternatively, into two pieces, the lens 40 being mounted on the part remaining

  of the tube along its edges so as to form the tube. The-

  advantage provided by a tube made in one piece by extrusion

  sion is that the lens can be made to include a greater number of facets 44 on a larger

  large radial portion of the tube to increase the relative size

the lens.

  The unit 12 furthermore preferably comprises additional concentration means in the form of two reflectors

  46 respectively extending from the side edges oppo-

  from the lens 40 towards the assembly 14 so as to reflect 07. the incident solar radiation which is transmitted through the

  lens 40 but for various reasons such as refraction

  tion and reflection, is not directly focused on

  14. The reflectors 46 are shown in Figures 2 and 4 as flat plates supported by themselves although the plates may be curved in a manner well known in the art to increase the concentration of solar radiation on the assembly 14 The reflectors can be fixed in position by any suitable means, for example

  example (1) by providing a support for reflectors 48 which

  stretches along the bottom of the tube 38 (opposite the lens 40) and carries the lower longitudinal edges of the reflectors 46, and (2) by providing appropriate support lips 50 which

  may be integral with the tube 38 near the long edges

  of the lens 40 to carry the longitudinal edges

  top of the reflectors 46.

  As best seen in FIG. 3, the preferred solar cell assembly 14 includes a group of solar cells 52 and is positioned relative to the reflectors 46 so that when the tube 38 is properly positioned relative to the sun ( position in which the sun, the central lens segment 42 and the assembly 14 are aligned), a maximum amount of incident solar radiation transmitted by

  the lens 40 and reflected by the reflectors 46 is concentrated

  tres esur the group of solar cells 52 of the assembly 14.

  The assembly 14 is preferably made according to the teachings of U.S. Patent No. 4,078,944 issued to Mlavsky on March 14, 1978 and U.S. Patent No. 4,144,095 issued to Mlavsky on March 13, 1979. The preferred assembly further comprises an enclosure. 54, a conduit-shaped absorber 56 and end caps 58 (only one of which is

  shown in Figure 3). In general, the structure is

  As shown in Fig. 13 of Mlavsky Patent No. 4,144,095, according to which the cooling duct 56 has a substantially rectangular cross-section so as to carry the group of solar cells 52, it is made of a heat-conducting material such as aluminum 08. or the like, and is supported at each end by the respective end cap 58. As described in US Pat.

  Mlavsky No. 4,144,095, the duct of rectangular cross-section

  The gullet 56 may be modified at each end in a circular cross-section so as to allow it to pass into the end cap 58, as shown at 60, so that

  waterproof. The fluid flowing in the duct 56 can be directly

  ge in an appropriate tube 61 which is preferably used to

  partly a fluid circulation loop. Electricity terminals

  The gangs 52 are suitably mounted on the group 52 as described in the Mlavsky patents to allow external electrical connection of the group 52 using for example wiring 63. The group of solar cells 52 can thus be hermetically sealed. in the casing 54, as described in the Mlavsky patents mentioned above, while being disposed within the concentration unit 12 to receive significant concentrations of solar radiation. The entire assembly 14 of the solar cell group can be mounted and suitably fixed in the tube 38 by any suitable means, such as a support

  in U 64, such a support being provided at each end of the

  14. Support 64 includes at least two adjusting threaded spindles 66 extending from opposite support arms 64 and cooperating with the diametrically opposed sides of assembly 14, and in particular the respective end cap 58 of so that the group of solar cells 52 is in front of the lens 40 and the assembly 14 is adjustable in the plane of the

  group 52 to ensure maximum concentration of

solar energy on the group.

  Referring again to the tube 38, the opposite sides of the tube are closed by end members 68. Preferably, these end members are in the form of a disc comprising

  an annular slot 70 on the inner side of the end element

  The tube can be fixed in position in any suitable manner, such as cementing. Each end member 68 further comprises a hollow tubular extension 72 extending 09.

  from the outer side of the end element and is posi-

  coaxially with an appropriate opening in the end member. The median axes of the extensions

  at the opposite ends of each unit are aligned and defined

  substantially the axis of rotation of this unit. Preferably, each extension 72 is positioned coaxially with respect to the cylindrical axis of the tube, although it is readily apparent that the aligned axes of the extensions 72 may be offset and

  parallel to the cylindrical axis. The end of each extension

  72 is connected to the support assembly 10 and in particular to the respective bearing support 30 and 34 by appropriate rolling means 74 (shown in FIG.

  unit 12 is fixed along the axis of rotation de-

  finished with extensions 72 and can easily turn around

  of this axis. Preferably the rolling means 74 comprise

  a rolling element. spherical 76 suitably attached to each extension 72, and rotatable in a spherical seat 78 mounted in a fixed and suitable manner in

  the respective hollow bearing supports 30 and 34 of the assembly

  10. The axes of rotation of the units 12 are

  are preferably located in a common plane.

  At least one of the end elements 68A is made for

  serve as a pulley forming part of the training

  designed to rotate each unit. In particular, the element 68A comprises a groove 80 located around its peripheral edge and intended to receive the cable 16. The groove

  is preferably helical and extends on the perimeter edge

  of the end member over at least 3600 and preferably more so that the cable 16 can be wound 3600 to the end member 68A so as to frictionally engage the slot without discomfort when the cable moves and the unit turns. Mechanical fixing means in the form of cable clamping means 81 (shown in FIG. 3) are preferably provided for fixing the cable

  in the groove 80 to ensure the rotation of the corresponding unit.

  12 when moving the cable. The means 81

  take two bolts 83 disposed in the groove 80 on the other hand and 10 of the cable 16 and a flange 85 fixed on the bolts to tighten the cable in the slot. The elements 68A of all the units 12 are arranged substantially in the same general plane so that the corresponding helical slots of the units are aligned and can cooperate with the single cable 16. The drive means intended to ensure the rotation of the units 12 comprise in in addition to the means of pulling cable

  18, shown generally in FIG.

  FIG. 5. These cable traction means comprise

  There is a base support 82 carrying a reversible motor 84, a cable tension bar 86, a bar guide frame 88.

  86, and pulleys 90. The reversible motor 84 is preferably

  this a motor geared down to relatively low rotational speed

  made so that screw 92 can be rotated

  one way or the other. The screw 92 rotates in a spherical nut

  94, the latter being fixed on one end of the bar 86 so that the rotation of the screw results in the linear displacement of the bar along its elongated axis. The guide frame 88 has a linear slot 96. More specifically, the frame 88 comprises two spaced L-shaped brackets fixed to the base support 82. The brackets can be fixed in any known manner such as by welding onto the support. basic, or alternatively, the brackets and bracket can be

  made in one piece by extrusion of plastic material.

  only at high strength. The bar 86 comprises suitable means such as guide rollers 98 which interact with

  the guiding frame 88 so as to prevent the bar 86 from rotating

  with the screw 92 when the latter rotates, and to move the bar 86 in the slot 96. The bar 96 further comprises cable attachment means such that the rod 100 attached to the end of the bar 86 next to the spherical nut 94. One end of the cable 16 is fixed on the rod 100, passes around the pulleys 90 and then passes into

  the slot 80 of the end element 68A of each unit 12.

  In this regard, all of the cable traction means is mounted within one of the side members 36A which protects them from an environment that might otherwise be otherwise disposed of.

  aggressive. The cable 16 starts from the pulleys 90 and passes into a

  appropriate opening in the sensitive lateral element 68A

  in the general plane delimited by the elements 68A of the units 12. The lateral element 66A is disposed below the plane delimited by the axes of rotation of the units 12 and preferably made so that the cable extends from the opening of the lateral element 66A tangentially with respect to. the end element

  68A of the nearest unit 12, wraps 3600 on the

  the end element of the unit and then passes to the end elements 68A of each of the remaining units 12 on which it winds. The remainder of the cable 16 passes into a suitable opening in the opposite side element 36B (the latter preferably also being disposed below the plane delimited by rotation axes of the units 12) where it is adequately energized. , for example by a spring

  tension 102, or a suitable counterweight disposed

  of the support assembly 10. The general plane delimited by the elements 36A and 36B is substantially tangential to the

  to all end members 68A.

  To assemble the capture assembly 8 the units 12 are mounted in the respective bearing supports 30 and 34. The tube

  61 and the cabling 63 of each unit can cross the

  hollow member 72 of the corresponding end member 68A, the bearing support 30, and the horizontal front member 28 to arrive at a suitable location. Because the assembly 8 is preferably made of tube or hollow pipe, the assembly can thus serve as a conduit for the tube 61 and the wiring 63 and thus protect them from an aggressive environment. The tube

  61 may be connected to a suitable heat exchanger (not

  presented) in which the heated fluid can be used and the cooled fluid can be returned by a similar tube in the assembly 14 to be recirculated in the conduit 56. Thus, in addition to the cooling of the group of solar cells 52, the fluid serves in addition to capture useful thermal energy accumulated in the unit of concentration. Similarly, the wiring 63 of all the units can be electrically connected to each other and to a suitable load, such as a cell 12.

  accumulation or an electric motor.

  In operation, the units may be oriented to the east by operating the motor 84 to turn the screw 92 and thereby move the bar 86 to a first position in the slot 96 (position shown in FIGS. as being farthest from the motor 84) so as to straighten

  the cable 16 and to rotate the units thus according to the orienta-

  desired. The motor can then be operated to maintain a predetermined speed so that the units rotate with a predetermined rotational speed to track the sun while providing maximum concentrated energy on the group of solar cells 52 of each set of groups. . At the end of the day, when the bar 86 is at the close end of the slot 96, the motor can be turned back, which turns the screw 92 so that the bar

  86 returns to its first position, extending the cable 16 to

  turn the units back to the position

eastward oriented.

  The operation just described is preferably carried out

  automatically. The pursuit operation may be

  equipped with an adequate clockwork mechanism since the position of the sun can always be predicted at any time. Thus, a clockwork mechanism can be suitably connected to the motor 84, so as to synchronize the speed of the motor with the passage of time in the day. The units 12 can be easily returned to their eastward orientation at the end of each day. Alternatively, a detector 104 is placed in a suitable location on one of the units to provide an electrical output signal representative of the position of the sun. The detector 104 can be of any type commercially available and preferably capable of detecting infrared radiation so that the detector can

  operate when the sky is overcast. In others two

  Contact breakers 106A and 106B may be disposed on the guide frame 88 at opposite ends of the slot 96 so that when the bar 86 is moved to the first position, to orient the units 12 eastward, the roller 98B 1 3.

  comes into contact with the switch 106B and closes it, and

  pouring, at the end of the day when the bar 86 is in the opposite position in the slot 86, the roller 98A contacts the switch 106A and closes. As shown in FIG. 6, the detector 104, the switches 106A and 106B and the motor 84 are electrically connected to a suitable control circuit 108 (the latter being of a type well known in the art.

  technique) for the output of detector 104 to change the speed of

  motor 84 to ensure correct and consistent tracking.

  Aunt of the sun when it crosses the sky. The contact of the roller 98A with the switch 106A causes the motor to go into reverse, which automatically rotates the screw 92, this rotation resulting in the return of the bar 88

  until the roller 98B comes into contact with the interrup-

  106B to orient the units 12 eastward for the next day.

hand.

  Although we have just described a preferred embodiment

  of the invention, it goes without saying that one can

  its modifications to the described apparatus without departing from the scope of the invention. For example, as shown in FIG. 7, the entire tube 38A, the prismatic lens 40 and the reflector holders 48A can be made in one piece by extrusion in a three-hole extrusion process. In this case, a cavity 110 is provided below the reflectors 48A

  to receive the set of solar cell groups 14.

  Reflectors can be easily made by fixing a

  flector 112 on the mutually opposed surfaces of the supports 48A so as to provide an optical system (consisting of the lens 40 and reflectors 46) identical to the system described and shown in FIGS. 1 to 5. Similarly, as shown in FIG.

  FIG. 8, the tube is shown as being made by extrusion

  with the reflectors 46A being mounted inside the tube relative to the absorber similar to that described and shown in Figure 4, with the difference that the reflectors 46A are sized to extend only on a part

  distance to the longitudinal edges of the

  Finally, if it is necessary to seal the group of solar cells 52 in the envelope 54, the envelope 54 and the end caps 58 could be closed.

  removed as well as the duct 56 mounted at each di-

  rightly on the respective end members 68, as shown in Figure 9. The solar collector assembly that has just been described has several advantages. Because the units 12 have a cylindrical cross-sectional configuration, they are less likely to be obstructed by obstacles such as sand or snow, and may further include end members 68A which serve both to close one end of

  each unit and to form a pulley forming part of the

  canyon of pursuit. In addition, locking up a set

  hermetically sealed 14 inside the large unit of con-

  12, relatively high concentrations of solar energy can be concentrated on a group of solar cells 52 and at the same time, the group 52 can be appropriately enclosed in an inert environment to

  inside the envelope 54. The support assembly 10 con-

  an improved support structure allowing for

  rotate the units of solar energy

  12. The lateral elements 36 being

  placed below the plane of the rotation axes of the units 12, they do not cast any shadow on them whatever the

  position of the sun, and the cable can be aligned tangentially

  with the end members 68A. In addition, the cable traction means 18 may be disposed within the side member 36A to protect them from an aggressive environment. The rotational drive mechanism of each of the units constitutes a rotational drive mechanism

  simple and yet unique. Other benefits and changes

  possible events will come to the mind of those skilled in the art.

15.

Claims (24)

  1. solar energy collection system, characterized in that it comprises in combination - at least one solar energy concentrator comprising (1) an elongate hollow tube with an axis of rotation comprising a lens allowing least partially at least a portion of the incident solar energy and extending around at least a portion of said tube for concentrating solar energy transmitted therethrough, (2) means for converting solar energy arranged inside the tube relative to said lens so that when the tube is in   a predetermined angular position about the relative axis   in the sun, solar energy transmitted through the   is focused on the means of energy conversion   and (3) a pair of end elements each   on the opposite ends of the tube, at least one of these end members being a pulley; a support assembly for supporting the tube so that it can rotate about said axis of rotation; and   rotation drive means comprising a cable   flexible hose cooperating with said pulley to rotate said tube relative to the support assembly around   of the elongate axis so that the tube is kept in a position   angle as the position of the sun changes. 2. System according to claim 1, characterized in that the lens consists of a prismatic lens extending over the entire length of the tube.   3. System according to claim 1, characterized in that   the tube is a straight circular cylinder.   4. System according to claim 1, characterized in that the means for converting solar energy comprise a group of solar cells and a conduit for supporting   the group of solar cells and to drive a fluid through   towards it in order to absorb the heat generated by   means of converting solar energy.   16. 5. System according to claim 4, characterized in that   said duct is mounted at each end on an element of respective tremity.   6. System according to claim 1, characterized in that the means for converting solar energy comprise a   envelope, a group of solar cells arranged in the   envelope and end caps sealingly attached to opposite ends of said casing to close the group of solar cells within said envelope.   7. System according to claim 6, characterized in that the means for converting solar energy comprise in   in addition to a conduit for supporting the group of   and driving a fluid through said envelope to   absorb the heat generated by the means of conversion of the solar energy.   8. System according to claim 7, characterized in that   said duct is mounted on end caps.   9. System according to claim 1, characterized in that   the pulley is in the form of a disc and comprises a groove   around the peripheral edge thereof, said groove having a shape allowing the cable to engage and remain in the groove and rotate the tube about the elongate axis when   a movement of the cable in the direction of its length.   10. System according to claim 9, characterized in that it further comprises means for fixing the cable in the groove.   11. System according to claim 9, characterized in that the rotation drive means further comprise   means for moving the cable in the direction of its length.   System according to claim 11, characterized in that the means for moving the cable comprise   means-drive connected to one end of the cable to   to place the cable in a first direction and means -   tensioners for moving the cable in the other direction.   13. System according to claim 12, characterized in that the drive means comprise a motor, a rod 17 of elongate shape so as to be driven by the motor and operatively connected to said cable for the action of the motor. moves the bar which, in turn, moves the cable according to the first direction.   14. System according to claim 13, characterized in that   that the drive means further comprise a screw   binding the motor to drive to said bar so that the   Turning the screw moves the bar in the direction of its length.   15. System according to claim 14, characterized in that said bar can move in the direction of its length towards (1) a first position for which said predetermined angular position has an orientation towards the east and (2) a second position for which said angular position   predetermined direction to the west.   16. System according to claim 15, characterized in that   it furthermore comprises control means intended to de-   place the bar between the first and second positions, the control means comprising a detector for providing a first signal representative of the position of the sun,   means responsive to the first signal to provide a second signal   when the position of the sun changes relative to the predetermined angular position, the motor being responsive to the second signal for moving the bar and cable so that the tube rotates about the elongate axis to the new predetermined angular position relative to the new position of the sun. 17. System according to claim 16, characterized in that the control means further comprise means for   at the level of each of the first and se-   conde positions to reverse the direction of rotation of said screw. 18. System according to claim 12, characterized in that the assembly of the support comprises hollow side elements disposed respectively opposite sides of the tube and the means   are arranged in a first element la-   while the tensioning means are arranged in the other side elements.   The system according to claim 18, characterized in that the lateral elements are arranged in a substantially common plane below the elongated axis so that the cable extends from the first lateral element tangentially with respect to the pulley. 'rolls 3600 on the pulley and passes on the other side elements.   20. System according to claim 9, characterized in that   the groove of said pulley is a helical groove.   21. System according to claim 9, characterized in that the means for converting solar energy comprise a group of solar cells and a cooling duct.   supporting the group of solar cells, means of trans-   mission for transmitting the electricity produced by the group of solar cells and means of transport for conveying a cooling fluid into said cooling duct, said first element further comprising a hollow extension connected to the support assembly, said   means of transmission and transport crossing   long to win the support package.   22. System according to claim 1, characterized in that the support assembly comprises a base, and a support frame connected to the base so as to be inclined relative thereto, the front of the frame being at a distance from one another. lower level at the rear of the frame, said frame comprising bearing supports at the front and at the rear for supporting said unit about the axis of rotation so that said axis extends   from the front to the rear of the chassis.   23. System according to claim 22, characterized in that the frame comprises lateral elements arranged in a   common plane located below the axis of rotation of said tube.   24. System according to claim 1, characterized in that   that the tube and the lens are made in one piece.   25. System according to claim 1, characterized in that the solar energy concentrator further comprises   reflecting means arranged inside the reflection tube   chir the solar radiation transmitted by the lens to the means   of solar energy conversion.   19. 26. System according to claim 25, characterized in that the reflector means comprise reflectors and means support of these.   27. System according to claim 26, characterized in that said tube, the lens and the reflector support means. become one with the other.