Abstract:
A self-powered light seeking apparatus and method for directing a target-plane towards a light source. The apparatus includes a photovoltaic powering arrangement configured to convert light energy into a driving current to power an actuator. The actuator is coupled to a support platform and is wired to the photovoltaic powering arrangement such that the polarity of the driving current causes the actuator to drive the target-plane towards alignment with the light source. A solar energy collection system including a photoelectric assembly for generating electricity from light incident upon an active area; a light concentrator comprising a substantially planar reflective surface subtending an angle to the active area such that light arriving along a line perpendicular to the active area and striking the reflective surface is reflected onto the active area; and a cooling unit configured to maintain the photoelectric assembly at an efficient operating temperature.

Description:
FIELD OF THE INVENTION 
       [0001]    The embodiments disclosed herein relate to self-powered alignment systems, in particular, to apparatus for maintaining alignment of a mounted body to a moving light source. The embodiments disclosed herein further relate to solar concentration systems. In particular, the embodiments refer to apparatus for increasing the efficiency and output of photovoltaic panels in a simple and cost-effective manner. 
       BACKGROUND 
       [0002]    In certain situations, such as the use of a solar panel, it is desirable to maintain equipment at a particular angle relative to a light source, such as the sun. In the specific case of a solar panel, such apparatus may be used to increase the solar energy received by the panel for the length of the day, from when the sun rises in the east until it sets in the west. The prior art has addressed this issue, including solutions making use of actuators following either a specific algorithm from a data processing unit, or acting upon information from light sensors processed by a data processing unit. These actuators require an external power source to supply the motive force for the actuators. Using known solutions, the essentially mechanical operation is controlled by complicated and possibly fragile and expensive computing units. Moreover, the prior art systems require possibly vulnerable connections to external power sources. 
         [0003]    For example, U.S. Pat. No. 5,317,145 to Corio, titled, “Radiation Source Detector And Tracker Control having a Shade Pole and Radiation Responsive Surface in the Shape of Narrow Bands” describes a tracker controller system in which a pair of photo-resistive cadmium sulfide sensors mounted in the shadow of a shade pole generate a voltage signal proportional to their resistive values which signal is delivered to a comparator circuit that causes a tracker driver to operate when the voltage signal falls outside of a voltage window established by the comparator circuit. 
         [0004]    It will be noted that Corio&#39;s system uses resistive cadmium sulfide sensors to detect light. These sensors are resistive elements which do not produce any power. Indeed Corio&#39;s system requires an external power supply to power its drivers. 
         [0005]    U.S. Pat. No. 4,225,781 to Hammons, titled, “Solar Tracking Apparatus” describes an invention that relates to a solar tracking device which tracks the position of the sun using paired, partially-shaded photocells. Auxiliary photocells are used for initial acquisition of the sun and for the suppression of false tracking when the sun is obscured by the clouds. 
         [0006]    It will be noted that although Hammons&#39;s system uses photocells, these are used as light sensors to detect the direction of the light source and are not of a size suitable to power the electric motors used for alignment. Again, an external power supply is required for Hammon&#39;s system to operate. 
         [0007]    It will be appreciated that solar energy is often harvested in environments where external energy sources are unavailable. There is therefore a need for a system that accurately can move an apparatus to maintain a specific optimum angle relative to the sun without the use of microprocessors or external power sources. The embodiments disclosed herein address this need. 
         [0008]    Further, in cases where the solar panel comprises photovoltaic cells for the production of electricity from solar power, a large portion of the cost of the system is dependent on the surface area of the active area covered by the photovoltaic cells. In general, when discussing such systems, reference is made to their efficiency in terms of cost-per-watt. Reducing the amount of photovoltaic cell material while maintaining the same wattage output is desirable. The prior art has addressed this issue and various solar concentrating methods have been devised, including those using lenses and parabolic or other curved mirrors to concentrate solar energy. Using known solutions, the solar energy may be concentrated, but the concentrating mechanisms themselves can become prohibitively expensive. 
         [0009]    In addition, although greater solar energy concentrated on a smaller photvoltaic panel will provide greater photovoltaic output, much heat is lost in the concentrated solar flux and as a byproduct of the photovoltaic conversion. Furthermore, the heating of the photovoltaic cells will itself lead to a loss of efficiency as the photovoltaic cell material heats beyond its most efficient operating temperature. This may also lead to permanent degradation of the photovoltaic cell material itself over time. 
         [0010]    It will be appreciated that there is therefore a need for a cost-effective system that can concentrate solar radiation onto photovoltaic cells and also cool such cells when the concentrated power overheats them. The embodiments disclosed herein address this need. 
       SUMMARY 
       [0011]    According to a first aspect of the disclosure, a self-powered alignment system is presented. It is one aspect of the current disclosure to present a self-powered light-seeking apparatus comprising at least one actuator configured to direct a target-plane towards a light source; and at least one photovoltaic powering arrangement configured to convert light energy into a driving current to power the at least one actuator; wherein the driving current has a polarity such that the actuator drives the target-plane towards alignment with the light source. 
         [0012]    Optionally, the at least one actuator is configured to drive the target-plane in a first direction when a positive potential difference is applied between its anode and its cathode and to drive the target-plane in a second direction when a negative potential difference is applied between its anode and its cathode. 
         [0013]    Variously, the at least one actuator may comprise a piston. Alternatively or additionally, the at least one actuator may comprise an electric motor. 
         [0014]    Optionally, the photovoltaic powering arrangement comprises: a first photovoltaic panel configured at a first angle to the target-plane and comprising at least one photovoltaic cell connected to an anode and a cathode such that the magnitude of potential difference between its anode and its cathode is dependent upon angle of light incident upon the photovoltaic panel; and a second photovoltaic panel configured at a second angle to the target-plane and comprising at least one photovoltaic cell connected to an anode and a cathode such that the magnitude of potential difference between its anode and its cathode is dependent upon angle of light incident upon the photovoltaic panel. 
         [0015]    According to some embodiments, the anode of the first photovoltaic panel and the cathode of the second photovoltaic panel may be connected to an anode of the actuator, and the cathode of the first photovoltaic panel and the anode of the second photovoltaic panel may be connected to the cathode of the actuator. 
         [0016]    Optionally, the first angle is equal and opposite to the second angle. For example, the first angle may be approximately equal to forty-five degrees to the target-plane and the first angle may be approximately equal to minus forty-five degrees to the target-plane. 
         [0017]    In selected embodiments, the first photovoltaic panel and the second photovoltaic panel may be configured such that they do not shade one another. 
         [0018]    Where appropriate, the photovoltaic powering arrangement may further comprise: a third photovoltaic panel configured at a third angle to the target-plane and comprising at least one photovoltaic cell connected to an anode and a cathode such that the magnitude of potential difference between its anode and its cathode is dependent upon angle of light incident upon the photovoltaic panel; and a fourth photovoltaic panel configured at a fourth angle to the target-plane and comprising at least one photovoltaic cell connected to an anode and a cathode such that the magnitude of potential difference between its anode and its cathode is dependent upon angle of light incident upon the photovoltaic panel. Optionally, the anode of the third photovoltaic panel and the cathode of the fourth photovoltaic panel are connected to an anode of at least a second actuator, and the cathode of the third photovoltaic panel and the anode of the fourth photovoltaic panel are connected to the cathode of the second actuator. 
         [0019]    According to further embodiments, the apparatus may comprise a first actuator configured to rotate the target plane about a first axis and connected to a first photovoltaic power arrangement. Additionally, the apparatus may further comprise a second actuator configured to rotate the target plane about a second axis and connected to a second photovoltaic power arrangement. Optionally, the first actuator comprises an azimuth actuator configured to drive the target-plane about a polar axis. Optionally, the second actuator comprises an elevation actuator configured to drive the target-plane about a declination axis. 
         [0020]    According to various embodiments, the apparatus comprise a solar panel mounted to a framework and configured to track the daily and seasonal movement of the sun across the sky. Additionally or alternatively, the apparatus may comprise a altazimuth support platform. Accordingly the apparatus may comprise a telescope. 
         [0021]    It is a further aspect of the disclosure to teach a method for aligning a target-plane towards a light source comprising:
       providing at least one actuator;   mounting a first photovoltaic panel to a support platform such that it is orientated at a first angle to the target-plane;   mounting a second photovoltaic panel to the support platform that it is orientated at a second angle to the target-plane;   connecting the photovoltaic panels to at least one actuator;   the photovoltaic panels powering at least one actuator to drive the support platform such that light intensity upon the first photovoltaic panel equals light intensity upon the second photovoltaic panel.       
 
         [0027]    According to a second aspect, the disclosure presents a device for aligning towards a bright light source comprising: a support platform rotatable about at least one axis; an actuator operable to rotate the support platform about the axis, the actuator having an anode and a cathode; and an independent power supply for powering the actuator. The power supply may comprise a first solar panel comprising at least one solar cell connected to an anode and a cathode such that the magnitude of potential difference between the anode and the cathode is dependent upon angle of light incident upon the solar panel; a second solar panel comprising at least one solar cell connected to an anode and a cathode such that the magnitude of potential difference between the anode and the cathode is dependent upon angle of light incident upon the solar panel. Accordingly, the anode of the first solar panel and the cathode of the second solar panel are connected to the anode of the actuator, and the cathode of the first solar panel and the anode of the second solar panel may be connected to the cathode of the actuator such that the actuator is powered directly by the solar panels with a polarity dependent upon angle of light incident upon each solar panel. 
         [0028]    According to a second aspect of the disclosure, a solar energy collection system is presented. The solar energy collection system may comprise: at least one photoelectric assembly for generating electricity from light incident upon at least one active area; at least one light concentrator comprising at least one substantially planar reflective surface subtending an angle to the active area such that light arriving along a line perpendicular to the active area and striking the reflective surface is reflected onto the active area; and at least one cooling unit configured to maintain the photoelectric assembly at an efficient operating temperature. Optionally, at least two the reflective surfaces are mounted upon wings to at least two sides of the active area. 
         [0029]    According to some embodiments, the photoelectric assembly comprises a plurality of active areas arranged into strips. Optionally, the light concentrator comprises a plurality of pairs of the wings flanking each of the strips. Such a light concentrator may be configured to collect light over an area larger than the active area by a factor between 1.5 and 3. In particular, the light concentrator may be configured to collect light over a catchment area larger than the active area by a factor of two. Accordingly, the substantially planar reflective surface may subtend an angle of 60 degrees to the active area. 
         [0030]    Where appropriate, the photoelectric assembly comprises an array of photovoltaic cells. Optionally, the heat exchanger is configured to maintain the photovoltaic cells at an efficient operating temperature. Accordingly, the cooling unit may comprise at least one heat exchanger adjacent to the photoelectric assembly. 
         [0031]    Such a heat exchanger may be in fluid communication with a fluid heating system. According to some embodiments, the heat exchanger comprises at least one pipe for transporting a coolant to and from the photoelectric assembly. Optionally, the coolant comprises water. 
         [0032]    In some embodiments, the heat exchanger comprises at least one fluid carrying pipe in thermal contact with the photoelectric assembly; and a heat trap encompassing the at least one pipe. 
         [0033]    According to particular embodiments, the solar energy collection system further comprises a tracking mechanism operable to align the photovoltaic assembly and the solar concentrator towards incoming light. In certain embodiments, the tracking mechanism is the self-powered light-seeking apparatus of the first aspect of the invention or the device for aligning towards a bright light of the second aspect of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0034]    For a better understanding of the embodiments and to show how it may be carried into effect, reference will now be made, purely by way of example, to the accompanying drawings. 
           [0035]    With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of selected embodiments only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects. In this regard, no attempt is made to show structural details in more detail than is necessary for a fundamental understanding; the description taken with the drawings making apparent to those skilled in the art how the several selected embodiments may be put into practice. In the accompanying drawings: 
           [0036]      FIG. 1  is a schematic representation of a first embodiment of a self-powered light seeking apparatus with a support platform on a single axis able to rotate east-west, side photovoltaic panels are shown as is the actuator and its connection to the support platform; 
           [0037]      FIG. 2  is a schematic representation of a second embodiment of a self-powered light seeking apparatus which also has a second axis for rotating north south, additional photovoltaic panels on the north and south sides and a second actuator; 
           [0038]      FIG. 3  schematically represents how side photovoltaic panels can be arranged facing outwards so that they do not shadow each other; 
           [0039]      FIG. 4  schematically represents how side photovoltaic panels can be arranged facing inwards in a staggered fashion so that they do not shadow each other; 
           [0040]      FIGS. 5A-C  show schematic cross-sectional representations of a fifth embodiment of a self-powered light seeking apparatus in various orientation towards the light source; 
           [0041]      FIG. 6  is an illustration of the electrical connections from one set of opposing side photovoltaic panels to their associated electrical actuator, and 
           [0042]      FIG. 7  is a flowchart representing a method for aligning a target-plane towards a light source. 
           [0043]      FIG. 8  is a schematic representation of a planar photovoltaic solar with a set of photovoltaic cells mounted on a platform on an axis with an actuator which is able to apply torque to rotate the platform about that axis; 
           [0044]      FIG. 9A  is a schematic representation of an embodiment of a planar solar concentration system using angled planar mirrors orientated North-South to concentrate solar energy onto a number of strips of photovoltaic cells; 
           [0045]      FIG. 9B  is a top view of the planar solar concentration system illustrating the angled planar mirrors and the strips of photovoltaic cells arranged in an orientation parallel to the North-South axis. 
           [0046]      FIG. 9C  is a schematic representation of another embodiment of a planar solar concentration system using angled planar mirrors orientated East-West to concentrate solar energy onto a number of strips of photovoltaic cells; 
           [0047]      FIG. 9D  is top view of the planar solar concentration system illustrating the angled planar mirrors and the strips of photovoltaic cells be arranged in an orientation parallel to the East-West axis. 
           [0048]      FIG. 10A  is a schematic diagram of a cross-section of a planar solar concentration system showing the planar reflecting surfaces directing light towards the photovoltaic panels; 
           [0049]      FIG. 10B  is a schematic diagram of a second cross-section of the planar solar concentration system of  FIG. 10A , showing a possible cooling system behind the photovoltaic panels; and 
           [0050]      FIG. 11  is a schematic representation of another embodiment that has a wider photovoltaic collecting area bracketed by larger planar reflectors for concentration of solar energy. 
       
    
    
     DETAILED DESCRIPTION 
     Alignment System 
       [0051]    Reference is now made to  FIG. 1  illustrating a first embodiment of a self-powered light seeking apparatus  100  configured and operable to track a light source such as the sun. The self-powered light seeking apparatus  100  includes a support platform  110 , an axis  120 , two photovoltaic panels  130 A,  130 B and an actuator  140 . 
         [0052]    The support platform  110  may be used for supporting equipment such that its position relative to a target plane is maintained. For example, the support platform  110  may be an altazimuth mount or other platform used to support a solar panel, telescope, other sun-monitoring equipment or the like. It is noted that the self-powered light seeking apparatus  100  may be configured to adjust the position of the support platform  110  such that the target plane is aligned towards a light source (e.g. aligned orthogonally to the direction of the incident sunlight). 
         [0053]    In a particular embodiment wherein the support platform is used to support a solar panel, it will be appreciated that the greatest intensity of solar energy can be collected by a collector aligned orthogonally to the direction of the incident sunlight. Accordingly, a solar panel, photovoltaic cells, solar heat exchanger, solar concentrator, a focusing system or the like may be mounted to the support platform  110  such that it remains parallel to the target plane. Consequently, as the support platform  110  tracks the apparent solar movement across the sky during the course of a day, the panel may be able to collect more of the available solar energy and with greater efficiency. 
         [0054]    The support platform  110  may be configured to rotate about at least one axis  120 . For example, where a polar axis  120  is provided parallel to a North-South meridian D, the support platform  110  may be rotatable in an East-West direction throughout the day. 
         [0055]    As the sun appears to move across the sky during the day, the incident solar rays originate from different parts of the sky. In the morning solar rays arrive from the eastern sky moving steadily westward throughout the day. As outlined hereinbelow, although this is not the only component of apparent solar movement, it is by far the largest component of the sun&#39;s diurnal movement. 
         [0056]    The actuator  140  may be coupled to the support platform  110  and operable to generate torque, thereby rotating the support platform  110  about the axis  120  such that equipment mounted thereupon may be directed towards the light source. Variously, an azimuth actuator  140  may be provided to rotate the support platform  110  about a polar axis  120 . Alternatively or additionally, an elevation actuator may be provided to rotate the support platform about a declination axis. 
         [0057]    Some possible actuators that may be powered by electrical power include rotary electrical motors, solenoids, pistons, DC actuators and the like. In some cases the mechanical force produced by the actuator is rotary in nature and in some cases it is linear, but there are numerous known methods for converting the force into the necessary torque for moving the support platform  110  about the axis  120 . 
         [0058]    In contradistinction to prior art tracking systems which draw power from external power supplies such as generators, power cells or mains lines, it is a particular feature of the self-powered light seeking apparatus  100  that the actuator  140  receives motive power from the two photovoltaic panels  130 A,  130 B 
         [0059]    The two photovoltaic panels  130 A,  130 B are arranged to either side of the axis  120 , for example to the east and the west of the axis  120 . Each photovoltaic panels  130 A,  130 B is operable to generate a potential difference when light is incident upon its active area  132 . The magnitude of the potential difference generated may depend upon the intensity of the light incident upon the active area  132 . 
         [0060]    The photovoltaic panels  130 A,  130 B are provided to supply power to the actuator  140 . Accordingly the panels  130 A,  130 B may be conductively connected to an anode and a cathode associated with the actuator  140 , such that mechanical force is produced on the application of potential difference across the anode and the cathode. 
         [0061]    It will be appreciated that an actuator  140 , which may be configured to operate with direct-current (DC), may produce mechanical force in opposing directions depending on the electrical polarity of the potential difference across the anode and cathode. Consequently, when the polarity of the potential difference changes, the direction of torque applied to the support platform  110  will also change. Optionally, the system is configured such that as the light source is out of the alignment with the support platform  110 , the torque produced by the actuator  140  may tend to move the support platform  110  closer to optimal alignment to the light source. In this way the system may provide negative feedback to track the sun through the day. 
         [0062]    Referring now to  FIG. 2  a second embodiment of a self-powered light seeking apparatus  200  is represented. The self-powered light seeking apparatus  200  of the second embodiment may include a support platform  210 , a first axis  220 , a first pair of two photovoltaic panels  230 A,  230 B and a first actuator  240 . It will be noted that the second embodiment of the self-powered light seeking apparatus  200  further includes a second axis  250 , a second pair of two photovoltaic panels  260 A,  260 B and a second actuator  270 . 
         [0063]    The second axis  250  may be at right angles to the first axis  220 . For example a first axis  220  may be a polar axis parallel to the North-South meridian D and the second axis  250  may be a declination axis S aligned approximately East-West, thereby enabling the support platform to pivot in a north-south fashion. 
         [0064]    The second actuator  270 , for example an elevation actuator, may be mechanically connected to the support platform or axis  250  enabling it to rotate the support platform  210  about the second axis  250 . 
         [0065]    The second pair of two photovoltaic panels  260 A,  260 B may be provided upon opposing sides of the second axis  250 , for example to the north and south of the support platform  210 . The second pair of panels  260 A,  260 B are electrically connected to the second electrical actuator  270 . 
         [0066]    It will be appreciated that due to the earth&#39;s axial tilt, seasonal changes can be observed in the apparent position of the sun in the sky. The elevation of the sun depends on both the latitude of the location and the specific date in the year. Using a biaxial system such as that described herein in relation to the second embodiment of the self-powered light seeking apparatus  200 , the sun may be tracked not only in its diurnal east-west path, but also through its seasonal north-south variations. 
         [0067]    It is particularly noted that unlike tracking systems of the prior art, systems described herein do not require computational elements to perform complicated calculations involving times and latitudinal data. 
         [0068]    According to some embodiments, the side-mounted photovoltaic panels are configured to reduce shadowing of one over the other. This may be arranged in a variety of ways. Referring now to  FIG. 3 , a third embodiment of a self-powered light seeking apparatus  300  is shown. The third embodiment of a self-powered light seeking apparatus  300  includes a support platform  310 , an axis  320 , photovoltaic panels  330 A,  330 B,  360 A,  360 B and an actuator  340 . 
         [0069]    It is noted that in the third embodiment of the self-powered light seeking apparatus  300  the photovoltaic panels  330 A,  330 B,  360 A,  360 B are arranged facing outwards from the support platform  310  such that they do not shadow each other. As such, the apparatus  300  can be used throughout the daytime period without significant deterioration of its negative feedback due to mutual shadowing by the side photovoltaic panels. 
         [0070]    Referring now to  FIG. 4 , a fourth embodiment of a self-powered light seeking apparatus  400  is shown, in which the axis  420  holds a support platform  410  and also two photovoltaic panels  430 A and  430 B. It is noted that the photovoltaic panels may be arranged inwardly facing and set up in a staggered fashion, as exemplified by the photovoltaic panels  430 A and  430 B. In such an embodiment as well, the photovoltaic panels  430 A and  430 B will not shadow each other. 
         [0071]    Furthermore, it will be appreciated that a self-powered solar tracking system will track the sun throughout the day until it is aligned towards the western horizon in the evening and remaining thus throughout the night. The configuration of the third or fourth embodiments allow the morning rays arriving from the east to be unobstructed such that they are incident upon the East facing solar panel  330 B or  430 B, thus allowing the actuator to realign the support platform  310  or  410 , respectively, towards the morning sun as required. 
         [0072]    Reference is now made to  FIGS. 5A-C  showing schematic cross-sectional representations of a fifth embodiment of a self-powered light seeking apparatus  500  in various orientations towards the light source (not shown). The cross section of the apparatus  500  represents the support platform  510  and side photovoltaic panels  530 A,  530 B. Also shown in the schematic is a depiction of incident light  590 . 
         [0073]    With particular reference to  FIG. 5A , it will be appreciated that when the support platform  510  is aligned to the light source, the light  590  impacting the first photovoltaic panel  530 A and the second photovoltaic panel  530 B will be of approximately the same intensity. This may be achieved, for example, by attaching the photovoltaic panels at opposing angles to the target plane. A starting value for calibration of such a system could be a forty-five degree angle to the target plane as shown in  FIG. 5 , although other angles may be used as suit requirements. The support platform  510  is parallel to the target plane such that when the support platform  510  is orthogonal to the incident light  590  from the light source (such as the Sun&#39;s rays for example), both photovoltaic panels  530 A and  530 B will be at forty-five degree angles to the light arriving from the light source. Where the panels  530 A and  530 B are arranged at similar opposing angles to the Sun, they receive similar intensity of sunlight. Accordingly both photovoltaic panels  530 A and  530 B will produce the same potential difference. 
         [0074]    Referring now to  FIG. 5B , the apparatus of  FIG. 5A  is shown tilted with respect to the incoming light  590  such that the second photovoltaic panel  530 B receives a greater intensity of light that the first photovoltaic panel  530 A. It will be appreciated that in such an orientation, the potential difference produced by the first photovoltaic panel  530 A will be smaller than that produced by the second photovoltaic panel  530 B. Similarly, referring now to  FIG. 5C , the apparatus of  FIG. 5A  is shown tilted with respect to the incoming light  590  such that the first photovoltaic panel  530 A receives a greater intensity of light that the second photovoltaic panel  530 B. It will be appreciated that in such an orientation, the potential difference produced by the second photovoltaic panel  530 B the first photovoltaic panel  530 A will be smaller than that produced by the first photovoltaic panel  530 A. 
         [0075]    The size and polarity of the discrepancy of potential differences generated by each photovoltaic panel may be used to drive an actuator to realign the apparatus  500  as shown in  FIG. 5A . Thus the orientation of the support platform may be maintained with respect to the incoming light. 
         [0076]    Referring now to  FIG. 6  showing a simple circuit diagram  600  of the conductive connections between an actuator  610  and two side photovoltaic panels  630 A and  630 B. Each of the panels  630 A and  630 B has an anode  631 A and  631 B, respectively, and a cathode  632 A and  632 B, respectively. The actuator  610  also has an anode  611  and a cathode  612 . 
         [0077]    The electrical connections from the side photovoltaic panels  630 A and  630 B would be connected in the fashion shown in  FIG. 6 . An electrical connection is made from the anode  631 A of the first panel  630 A and the cathode  632 B of the opposing panel  630 B to the cathode  612  of the actuator  610 . Similarly an electrical connection is made from the cathode  632 A of the first panel  630 A and the anode  631 B of the opposing panel  630 B to the anode  611  of the actuator  610 . When both photovoltaic panels  630 A and  630 B are receiving equal amounts of light energy, the potential difference produce by both will be the same, so the potential difference across the anode  611  and cathode  612  of the actuator  610  will be zero and the actuator  610  will not move. As the sun moves across the sky and the light energy incident on the opposing photovoltaic panels  630 A and  630 B changes, a potential difference will be produced across the terminals  611  and  612  of the actuator  610 , causing the actuator  610  to operate, turning the target plane (and the attached photovoltaic panels  630 A and  630 B) more directly at the sun. Once the optimum angle is attained, the potential difference across the terminals  611  and  612  of the actuator  610  will once again be zero and the system will stop at equilibrium until a further detectable shift occurs in the sun&#39;s position. 
         [0078]    Referring now to the flowchart of  FIG. 7 , a method  700  for aligning a target-plane towards a light source is presented. The method involves: providing at least one actuator  710 , mounting a first photovoltaic panel to a support platform such that it is orientated at a first angle to the target-plane  720 , mounting a second photovoltaic panel to the support platform that it is orientated at a second angle to the target-plane  730 , connecting the photovoltaic panels to at least one actuator  740 , and the photovoltaic panels powering at least one actuator to drive the support platform such that light intensity upon the first photovoltaic panel equals light intensity upon the second photovoltaic panel  750 . 
       Solar Concentration System 
       [0079]    Reference is now made to  FIG. 8 , which shows a schematic of a photovoltaic solar collection apparatus  800  configured an operable to track the sun. The photovoltaic solar collection apparatus  800  includes a platform  830  covered with photovoltaic cells  810  supported on an axis  820  and coupled to an actuator  870 . The actuator  840  is configured to mechanically generate torque to rotate the platform  830  about the axis  820 . 
         [0080]    In such an apparatus, it will be appreciated that the greatest intensity of solar energy will impinge on the photovoltaic cells when the platform  830  is aligned normal to the direction of the sun&#39;s radiation. It will further be appreciated that in such an embodiment, the only way to collect more energy would be to increase the active area of the platform  830 , i.e., the area covered with photovoltaic cells  810 , thereby increasing the number of cells. 
         [0081]    It is noted that increasing the number of cells may significantly increase the cost of the collection apparatus. Furthermore, adding more photovoltaic cells may make the apparatus heavier and subject to large wind forces thereby increasing operating costs and wear and tear on the actuator  840 . 
         [0082]    Referring now to  FIG. 9A  a first embodiment of a solar concentration system  900  is represented. The first embodiment might include a platform  930  supporting a light concentrator  950  and a photoelectric assembly  910 . 
         [0083]    The platform  930  may be coupled to a tracking mechanism  920 , for example by being mounted upon an axis  922  and coupled to an actuator  924  such that the actuator  924  can mechanically generate torque to rotate the platform  930  about the axis  922 . 
         [0084]    It is noted that in contradistinction to other systems  800  such as described hereinabove in relation to  FIG. 8 , the photovoltaic assembly  910  has an active area  912  that only partially covers the platform  930  with photovoltaic cells which are arranged into strips, e.g.,  912 A-C. 
         [0085]    The light concentrator  950  includes a system of reflectors  952 A-F covering the remaining area of the platform  930 . The reflectors  952 A-F are planar and are configured to subtend at an angle to the plane of the active area  912  such that light arriving at an angle normal to the plane and striking the reflector  950  may be reflected onto the photovoltaic cell strip. 
         [0086]    It will be appreciated that the incident radiation upon the platform either strikes the photovoltaic cell strips  912 A-C directly or else is directed from reflectors  952 A-F toward the photovoltaic cell strips  912 A-C. Consequently, the amount of radiation striking the photovoltaic strips  912 A-C will be approximately the same as the amount of radiation, which unimpeded, would have struck the area of the platform  930  as a whole. Accordingly, using the solar concentration system described herein, the same amount of solar radiation may be collected with fewer of photovoltaic cells being used. 
         [0087]    The solar concentration system  900  may further comprise a tracking mechanism  920  operable to orientate the platform  930  towards the sun during its apparent daily movement across the sky such that the photovoltaic cell strips  912 A-C are aligned normal to the direction of the sun&#39;s radiation and the reflectors  952 A-F of the light concentrator  950  maintain a functional alignment and do not shade the active area. In addition, a seasonal tracking mechanism may be employed to orientate the platform  930  by changing its elevation such that it points towards the sun during its apparent seasonal movement above and below the equator. See Alignment Systems, above, for a detailed discussion of tracking systems that may be employed in the solar concentration system  900 . For example, the axis  922  may hold two photovoltaic panels  925  that control and power the actuator  924 . See the discussion above regarding the self-powered light seeking apparatus  400  for further discussion of a possible a tracking system for use with such a system. Alternatively, other tracking systems, for example as discussed above regarding self-powered light seeking apparatus  100 ,  200  or  300 , may be used. Still other tracking systems may be used as known in the art. 
         [0088]    Making reference to  FIG. 9B , the photovoltaic strips  912 A-C and the reflectors  952 A-F may be arranged in an orientation parallel to the North-South axis over the platform  930 . 
         [0089]    Alternatively, making reference to  FIG. 9C , another embodiment of a planar solar concentration system  900 ′. The system  900 ′ may use an East-West oriented light concentrator  950 ′ and photovoltaic assembly  910 ′. Accordingly, East-West oriented angled planar mirrors  952 A′-F′ to concentrate solar energy onto a number of East-West oriented strips  912 A′-F′ of photovoltaic cells. It has been found that using an East-West orientation for the light concentrator  950 ′ and photovoltaic assembly  910 ′, may significantly reduce shadowing of the photovoltaic cells by the mirrors throughout the day. 
         [0090]    It will be appreciated that in many areas of the world where photovoltaic current generation may be theoretically practical, the costs of importing expensive photovoltaic cells to use in new units or to use as replacements may be prohibitive. The concentrating arrangements  900 ′ described above in relation to  FIG. 9A-D  may reduce the amount of photovoltaic cells needed to extract the same amount of energy from the same solar energy-collecting field. In this way the solar collection apparatus can become more cost effective to run. Moreover, the reflectors  952 A-F,  952 A-F′ of the light concentrator  950 ,  950 ′ need not be fashioned into curved shapes, thus allowing simpler planar reflectors to be used, which are cheaper to manufacture and easier to assemble. 
         [0091]    For example, the platform  930  may comprise a lightweight fiberglass mold upon which the photoelectric assembly  910 .  910 ′ and light concentrator  950 ,  950 ′ may be mounted. Where appropriate, reflective paint may be used to coat an angled mold to form reflectors  952 A-F,  952 A-F′. 
         [0092]    Referring now to  FIG. 10A , a first cross-section  1000 A is presented of an embodiment of a planar solar concentration system. This cross-section shows the photovoltaic cell strips  1012 A-C, the reflectors  1052 A-F and a cooling unit  1060 . Also shown is a depiction of solar radiation  1040  striking the reflectors  1052 A-F and being redirected towards the photovoltaic cell strips  1012 A-C. 
         [0093]    It is noted that in the embodiment of the planar solar concentration system  1000  shown in  FIG. 10A , the area occupied by the reflectors  1052 A-F is the same as the area occupied by the photovoltaic cell strips  1012 A-C. Further, the reflectors  1052 A-F have the same width as the width of the photovoltaic cell strips  1012 A-C and subtend at an angle of 60 degrees from the plane of the active area. It will be appreciated that in such a configuration, the photovoltaic cell strips  1012 A-C, in aggregate, will cover half of the total light catchment area. It will be further be appreciated that in such a configuration, when the photovoltaic cell strips  1012 A-C are aligned normal to the direction of the sun&#39;s radiation, the sun&#39;s radiation reflected by the reflectors  1052 A-F are directed to precisely cover the area of the photovoltaic cell strips  1012 A-C, thus reducing or eliminating unevenness in the concentration of the solar radiation that the photovoltaic cell strips  1012 A-C receives and solar radiation being reflected away from the system  1000  before striking one of the photovoltaic cell strips  1012 A-C. As a consequence, the planar solar concentration system  1000  enables the concentration of solar radiation striking the photovoltaic cell strips  1012 A-C by a factor of 2. It has been found that a concentration factor of between 1.5 and 3 may increase the electrical output of photovoltaic cells without overheating the system to reduce efficiency. 
         [0094]    In a system making use of concentrated solar energy, it will be appreciated that the areas where the solar energy is concentrated experience increased heating, both from solar infra-red energy and from inefficient conversion of impacting photons to electrical current in the photovoltaic cell strips  1012 A-C. It will further be appreciated that such increased heating can cause a deterioration of the conversion efficiency of such photovoltaic cell strips  1012 A-C and may also pose a threat of permanent degradation to the photovoltaic cell strips  1012 A-C. The cooling unit  1060  provides a heat-exchange system capable of maintaining the photovoltaic material at an efficient operational temperature. 
         [0095]    The cooling unit  1060  comprises a plurality of pipes  1062 A-C in thermal contact with the photovoltaic strips  1012 A-C. Placing the pipes  1062 A-C beneath the photovoltaic cell strips  1012 A-C allows a stream of coolant to circulate and cool the photovoltaic cell strips  1012 A-C to an efficient operating temperature. 
         [0096]    It is further noted that the cooling unit  1060  may further include a heat trap  1068  in which the heat exchange pipes  1062 A-C are enclosed. Such a heat trap  1068  may create a greenhouse effect or otherwise prevent heat losses to the environment thus increasing the amount of heat being transferred to the pipes  1062 A-C. 
         [0097]    Referring now to  FIG. 10B  another cross-section  1000 B is presented of the embodiment of a planar solar concentration system. The cooling unit  1060  includes coolant pipes  1062 A-C in fluid communication with feeder lines  1064 ,  1066 . A coolant, such as water or the like, may be drawn into the inlet feeder line  1064 , through the coolant pipes  1062 A-C in thermal contact with the photovoltaic strips  1012 A-C, and into the outlet feeder line  1066 . 
         [0098]    The feeder lines  1064 ,  1066  may be connected to a domestic water heater, air conditioning unit, desalination plant or other such system whereby the heated coolant may be utilized. 
         [0099]    It will be appreciated that due to the inefficiency of known photovoltaic conversions and because of the inherent presence of infrared light in the solar spectrum, any solar panel, even one configured to use visible or ultraviolet light, will experience heating. It is a particular advantage of the embodiments described above in relation to  FIGS. 10A and 10B  that this heat energy, which would otherwise be wasted, may be used. A heat exchange mechanism may be utilized both as a cooling system for the photovoltaic apparatus and as a thermal power generator. 
         [0100]    The use of such a heat exchange mechanism increases the overall energy efficiency of the solar collection apparatus by a large factor, perhaps enough to change a non-economic solar collection system into an efficient solar collection system. 
         [0101]    It is further noted that where an arrangement such as described in relation to  FIGS. 10A and 10B , is mounted upon a tracking mechanism, at least one heat exchange pipe  1062  may further serve as an axis of rotation. For example the arrangement may be rotatably coupled to a central North-South aligned pipe  1062 B such that it may rotate to align to the sun during its apparent daily motion across the sky. 
         [0102]    According to various embodiments, systems may utilize a single active area or a plurality of active areas such as strips. Referring now to  FIG. 11 , showing a fourth embodiment of a solar concentration system  1100 , the solar concentration system  1100  of the fourth embodiment has a single larger active area  1112  and two wing reflectors  1150 A,  1150 B flanking the active area  1112 . The reflectors  450 A,  450 B are supported by wings mounted to the support platform  1130  and may redirect impacting light towards the active area  1112 . In this way, the system may be retrofitted to existing solar collectors to redirect incoming solar radiation over a much larger apparent area to the same collecting photovoltaic panels. It is noted that the active area  1112  is supported by a platform  1130  coupled to a tracking mechanism  1120  to prevent the wings shading the active area. The platform  1130  may aligned to the sun by means of an actuator  1124 . See Alignment Systems, above, for a detailed discussion of tracking systems that may be employed in the solar concentration system  1100 . For example, the axis  1122  may hold two photovoltaic panels  1125  that control and power the actuator  1124 . See the discussion above regarding the self-powered light seeking apparatus  400  for further discussion of such a tracking system. Additionally or alternatively, other tracking systems, such as discussed above regarding self-powered light seeking apparatus  100 ,  200  or  300 , may be used. 
         [0103]    The scope of the disclosed subject matter is defined by the appended claims and includes both combinations and sub combinations of the various features described hereinabove as well as variations and modifications thereof, which would occur to persons skilled in the art upon reading the foregoing description. 
         [0104]    In the claims, the word “comprise”, and variations thereof such as “comprises”, “comprising” and the like indicate that the components listed are included, but not generally to the exclusion of other components.