A modular single axis solar tracking device and a system using same

Abstract

A single axis solar tracking module is provided which comprises: two solar panels rotatably coupled to a rotational axis, wherein the rotational axis comprises a rod extending laterally along the at least two solar panels, wherein a first part of that rod extends laterally along a first of the two solar panels, and comprises a protrusion that matches a cavity starting from an edge of the second part of the rod, and wherein the second part of the rod extends laterally along a second of the two solar panels that is located adjacent to the first solar panel, so that by inserting the protrusion into the cavity, the first and second solar panels are attached to each other and the combined rod is used as their rotational axis; a frame, for mounting the two solar panels thereat; and a transmission system configured to rotate the frame of the single axis solar tracking module with the two solar panels mounted thereat.

Description

[0001] A MODULAR SINGLE AXIS SOLAR TRACKING DEVICE AND A SYSTEM

[0002] USING SAME

[0003] FIELD OF THE INVENTION

[0004] The present invention relates in general to systems for utilizing solar radiation, and particularly to solar systems implementing a single axis tracking technology.

[0005] BACKGROUND OF THE INVENTION

[0006] The ever-growing environmental problems of increasing energy demand and resource shortages require new technologies for utilizing energy sources and particularly utilizing renewable sources. One such technology relies on using solar trackers which are configured to tilt their solar collecting surfaces towards the sun. Among these solar trackers one may find solar panels, parabolic troughs, and heliostats.

[0007] For flat-panel photovoltaic systems, where solar radiation is converted into electric energy, the trackers are used to minimize the angle of incident between the incoming sun rays and photovoltaic panels. Reducing this angle increases the amount of energy produced from a given amount of installed power generating capacity.

[0008] As the pricing, reliability and performance of single-axis trackers have improved, the systems have been installed in an increasing number of utility-scale projects .

[0009] In certain photovoltaics applications, trackers are used. Tracking systems are used because for such systems to operate, the collection efficiently of solar radiation is enhanced when the optical axis of the trackers is aligned with incident solar radiation, so that the solar photovoltaic collector is able to maintain its relative position throughout the day by remaining in a normal position relative to the incident solar radiation. In other words, the use of a single axis tracking is implemented by having the collector oriented at azimuth north to south, and the tracking is affected in one direction - east to west across the day. Such field of photovoltaic collectors are typically characterized by having a long chain of photovoltaic panels, extending from south to north that is mounted on a tracker frame which tracks the sun from east to west. Such fields of photovoltaic panels typically make use of a single motor for the rotation of such a chain of photovoltaic panels in order to improve the system' s cost effectiveness. Thus, the trackers implemented in these fields that are known in the art, are designed for a maximal load of panels per tracker, using heavy duty components and reinforced materials. Such a design may further support another need, namely, having fields' configuration that is robustness to torque that might develop due to wind forces that act on the long chain of collectors. In other words, using a wide massive beam as well as heavy duty components and reinforced materials is the prior art common solution to minimize the risks of exposure to failures due to developing torques and moments on the collectors' structure.

[0010] Moreover, the cost optimized design of photovoltaic ("PV") fields relies on using very long tracking chains where the supporting skeleton beam and rotating mechanism are mounted on the collector as described for example in the publications US 20190199276, US 9806669 and US 8459249. Another solution was proposed by US 20190199276 that discloses combining several long single axis trackers by using one moving motor via a linear rod or a cable that link all the rotating axes of the trackers. This way, the rotation of many panels can be affected by a single motor. The beam can have a rounded cross section (US 20210103302) or a square cross section (US 9806669) .

[0011] However, the prior art solutions have a number of drawbacks. Rotating an increasing number of PV panels using the same rotating motor, results in an increasing weight which causes problems that adversely affect the motor' s operation. Especially, having a large number of panels in a chain might create a large momentum, particularly under windy conditions, in which case, the motor will not be capable to operate properly by rotating the chain of panels as required.

[0012] Another disadvantage of the prior art systems in which such rigid tracking arrays designs are implemented, is, that the area used for the installation of a PV field should have a uniform topography (e.g. , a flat area, a single slope area, etc. ) , as otherwise if the area is not leveled, the moment that will be developed at the rigid beams will cause its failure. Consequently, a typical solution to this disadvantage is flattening of a large area designed for the installation of the PV field, which is a cumbersome task that has to be performed by using heavy machinery.

[0013] Moreover, there is another disadvantage of the prior art systems which has an increasing significance lately. This disadvantage arises from the need to install PV trackers on non-flat areas such as roofs, areas with non- uniform topography, fences, etc. Due to the nonuniformity of the ground level at which the PV panels are installed, there is a need to change the angles or orientation of the panels which are part of the chain of panels.

[0014] Furthermore, the relatively recent use of bi-facial PV panels, which are more efficient but need clear space from both sides of the panel, create a challenge where the rigid beam causes a penalty of shadowing and / or a need to rotate the heavy beam itself.

[0015] Another disadvantage of the prior art solutions is, that the heavy structure of the tracker has to be mounted on a large number of supports along the rotating axis. These supports cause certain shadowing that blocks radiation reflected from the ground. When implementing a bifacial PV technology, such a shadowing effect becomes quite a substantial disadvantage.

[0016] Another disadvantage associated with the prior art solution is the maintenance issue. Since these prior art solutions rely on using rigid structures that include heavy motors and arrays that comprise many units, once there is a need to carry out a repair / maintenance, it leads to a shutdown of many operational units.

[0017] Yet another problem that the prior art trackers have, arises from the recent trend that photovoltaic solar fields would not have an adverse footprint on the environment. Hence, applications such as dual use of the fields' areas became increasingly more interesting. For example, use of agriculture fields, green houses, fences, sideroads and roofs for generating solar driven energy thereat. Therefore, generating photovoltaic energy under complex topographical conditions becomes a leading necessity. However, to meet this challenge, systems unlike the prior art systems, require tracking solutions that can deal with such a complexity.

[0018] The present invention seeks to provide a solution that overcomes the above disadvantages of the prior art systems .

[0019] SUMMARY OF THE DISCLOSURE

[0020] It is therefore an object of the present invention to provide a solar tracking device for use in a solar field which improves the operational efficiency of the solar field.

[0021] It is another object of the present invention, to provide a solar tracking device having a substantially reduced weight, which in turn reduces certain problems described-above that occur while using prior art trackers .

[0022] It is another object of the present invention, to provide a solar tracking module that enables using a flexible solar field design, by simply connecting any required number of panels' modules to each other.

[0023] It is another object of the present invention, to provide a solar tracking device that is adapted to be installed in a solar field in a way that is essentially free from problems associated with the installation of a solar field in a topographically non-uniform area.

[0024] It is another object of the present invention, to provide a solar tracking module that reduces substantially maintenance problems associated with maintaining a solar field where the solar tracking modules are installed.

[0025] It is another object of the present invention, to provide a solar tracking module that is adapted to substantially reduce shadowing effects in a field comprising such solar tracking modules.

[0026] Other objects of the invention will become apparent as the description of the invention proceeds.

[0027] According to a first embodiment, there is provided a single axis solar tracking module, comprising: at least two solar panels rotatably coupled to a rotational axis, wherein the rotational axis comprises a rod extending laterally along the at least two solar panels, wherein a first part of the rod extends laterally along a first of the at least two solar panels, and comprises a protrusion that matches a cavity starting from an edge of the second part of that rod, and wherein the second part of the rod extends laterally along a second of the at least two solar panels that is located adjacent to the first solar panel, so that by inserting the protrusion into the cavity, the first and second solar panels are attached to each other thereby obtaining a combined rod, and wherein the combined rod is used as the solar panels' rotational axis; a frame, for mounting the at least two solar panels thereat ; a transmission system configured to rotate the frame of the single axis solar tracking module with the solar panels mounted thereat.

[0028] In the following description and claims, the following terms should be understood to be used interchangeably while still having the same meaning: "single axis solar tracking module", "solar tracking module", "tracking module" and "module". Similarly, the terms "single axis solar tracking modules", "row of solar tracking modules" and "tracker" are also used interchangeably and have the same meaning.

[0029] According to another embodiment of the present disclosure, the single axis solar tracking module further comprises a motor configured to rotate the single axis solar tracking module by using the transmission system thereof .

[0030] In accordance with another embodiment of the present disclosure, at least one of the two solar panels is a bifacial photovoltaic panel.

[0031] According to still another embodiment, the single axis solar tracking module further comprises a static beam structure. The static beam structure is not located near the panels, and may be part of a structure that the single axis solar tracking module is being installed thereat .

[0032] By yet another embodiment, the protrusion and the cavity have both a polygonal cross section.

[0033] According to another embodiment the single axis solar tracking module is configured to be associated with a structure beam located away from the rotational axis, at a distance which is equal to at least half of the solar tracking module' s width.

[0034] In accordance with another embodiment, the single axis solar tracking module is configured to be connected to another such a single axis solar tracking module, by using a flexible joint.

[0035] By still another embodiment, the frame of the single axis tracking module is configured to be attached to an object that has already been installed at a field where the single axis solar tracking module is about to be mounted .

[0036] According to another embodiment, the single axis tracking module further comprises a radiation measuring sensor. Preferably, according to this embodiment, the single mode tracking module is configured to operate also in a solar backtracking mode. Solar backtracking mode refers to an operational mode that aims to minimize PV panel-on-panel shading, but yet be positioned as close as possible normal to the instantaneous sun orientation, (or in the present case, a row of the solar tracking modules on another row of the solar tracking modules) , thus avoiding production losses, since a solar tracker, or a linked solar tracker row, when used near another, shades the adjacent other solar tracker particularly during early morning and late afternoon.

[0037] According to another embodiment, the single axis tracking module is configured to operate in a way that the two solar (photovoltaic) panels can reach up to ±90° relative to a virtual horizontal plane.

[0038] By still another embodiment, the transmission system of the single axis solar tracking module is further configured to compensate for a distance extending between a center of the transmission system's final (last) gear wheel and between a center of mass of the at least two solar panels, by using a shift movement being proportional to an angle generated between the single axis solar tracking module and the ground, by the transmission system's final gear wheel rotation. Such proportional shift can be achieved by using a further, smaller grooved wheel which is positioned concentrically to the (outer) final gear wheel. This smaller grooved wheel may be attached to a linear (or nearly linear) grooved rod so that any rotational movement of the final gear wheel will cause a proportional linear shift. The ratio between the last gear wheel and the additional smaller wheel, that is responsible for the linear shift transfer, can be adjusted by doing a 90° degrees panel shift, so that the linear shift will move the center of mass of the at least two solar panels, exactly above the rotation axis, thereby eliminating the adverse impact of the torque generated due to the at least two solar panels weight .

[0039] In accordance with another aspect of the present disclosure, there is provided a system comprising a plurality of single axis tracking modules of the present invention, wherein part of the plurality of single axis tracking modules are installed and operative above the operating remaining static or single axis tracking modules belonging to the plurality of single axis tracking modules. According to another aspect of the present disclosure there is provided a method for use in a solar system comprising a plurality of single axis tracking modules (i.e. , photovoltaic panels) , wherein the method comprises a step of utilizing a radiation measuring sensor installed remotely from one or more of the single axis tracking modules.

[0040] In accordance with yet another embodiment of the latter aspect, the method further comprises a step of utilizing a sensor installed underneath the one or more single axis tracking modules' plane in order to limit the angular tracking range of the one or more single axis tracking modules, to a minimal rotation. Preferably, the rotation of the one or more single axis tracking modules is limited to a near vertical angles, thereby limiting the shadowing of the one or more single axis tracking modules' panels at the middle of the day and allowing passing of sun rays.

[0041] BRIEF DESCRIPTION OF THE DRAWINGS

[0042] For a more complete understanding of the present invention, reference is now made to the following detailed description taken in conjunction with the accompanying drawings in which simplified schematics of the single axis solar tracking module are illustrated, wherein :

[0043] FIG. 1 - illust rates the schematic view of a single axis solar tracking module construed according to an embodiment of the present invention;

[0044] FIG. 2 - illust rates a schematic blown view of part of the single axis solar tracking module of FIG. 1;

[0045] FIG. 3 - demonstrates two single axis solar tracking modules that are connected to each other, where each of these two modules has a different orientation from the other;

[0046] FIG. 4 - presents an embodiment of the present invention for overcoming topography problems created when installing a plurality of single axis solar tracking modules on slanted roofs;

[0047] FIG. 5 - demonstrates an embodiment of the present invention by which the single axis solar tracking module can reach up to + / - 90° position relative to the ground;

[0048] FIG. 6 - exemplifies an embodiment of the invention for implementing solar backtracking mode;

[0049] FIG. 7 - illust rates an embodiment of the present disclosure wherein a plurality of single axis solar tracking modules are installed in an agricultural field;

[0050] FIG. 8A and FIG. 8B - illust rate an embodiment for implementing the single axis solar tracking modules of the present invention, on sideroad fences. FIG. 8A illustrates their tilt angle at about noon time, whereas FIG. 8B illustrates their tilt angle during morning or evening times;

[0051] FIG. 9 - illust rates an embodiment for implementing the single axis solar tracking modules of the present invention on greenhouses;

[0052] FIGs . 10A to IOC - demonstrate an embodiment of the present invention, implementing installation of the single axis solar tracking modules in a two levels' configuration, where the different FIGs. present their different inclination angles during the day;

[0053] FIG. 11 - illust rates an embodiment of the present invention, implementing a solution to compensate for a distance extending between a center of the transmission system's last gear wheel and a center of mass of the two solar panels; and FIG. 12 - demonstrates an embodiment of the present invention for adjusting the ratio between the last gear wheel and an additional smaller wheel by affecting a 90° degrees panel shift.

[0054] DETAILED DESCRIPTION

[0055] In this disclosure, the term "comprising" is intended to have an open-ended meaning so that when a first element is stated as comprising a second element, the first element may also include one or more other elements that are not necessarily identified or described herein, or recited in the claims.

[0056] In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It should be apparent, however, that the present invention may be practiced without these specific details .

[0057] The present invention aims to provide a solar tracking device that can be installed in areas having varying topography, existing infrastructures, roofs, greenhouses and fences, in other words, constrains to which the systems known in the art, cannot provide a solution .

[0058] Preferably, when installing the single axis solar tracking modules of the present invention, they will be positioned so that their rotational axis will coincide with the north-south direction, thereby enabling them to track the solar irradiation effectively by moving from east to west throughout the day.

[0059] FIG. 1 illustrates a schematic view of a single axis solar tracking module 15 construed according to an embodiment of the present invention. In this example, as can be depicted from this FIG. , single axis solar tracking module 15 comprises two solar panels that are held within a frame, which is mounted on a solid beam 16 (the latter is not a part of the single axis solar tracking module 15) . Beam 16 is associated with a support pillar 17, so that the structure of beam 16 and pillar 17 supports the weight of tracking module 15 attached thereto. A thin rod, shown in this FIG. as a thin rod that comprises two parts 12 and 13, has an axis connected to element 14 via a series of gears that are configured to rotate the frame of panel frame solar tracking module 15 and the two solar panels thereof. In this example, element 14 is a half-circular large gear, attached directly to the support frame of the solar panels, as will be further elaborated. As already explained, the single axis solar tracking module typically comprises two solar panels (but obviously not restricted to two) as shown in this FIG. , however, when installing these solar modules as part of a solar field, a raw of solar tracking modules may be of any designed length by simply connecting the modular single axis solar tracking modules to each other in series, thereby achieving the required length. Element 18 is a metal post that connects the beam to the rotation axis of single axis solar tracking module 15. The length of element 18 determines the space extending between beam 16 and the two solar panels. Therefore, in cases that a larger space is required between beam 16 and the solar panels, or between beam 16 and the rotation axis of solar tracking module 15, element 18 is made a longer element, to suit this requirement. It should be noted that the solution provided by the present invention, by which there is a separation of the beam element from the rotating elements, provides an advantageous option to have an independent rotation-tracking mechanism that is a light weight mechanism, hence does not need to provide a support for a heavy weight.

[0060] FIG. 2 illustrates a blown schematic view of part of the single axis solar tracker of FIG. 1. The part of the single axis solar tracking module 15 shown in FIG. 2 is the part which enables the single axis solar tracking module 15 to be connected to another such a single axis solar tracking module (i.e. , the modularity of the solar system is obtained by using any number of required single axis solar tracking modules) , namely, thin rod parts 12 and 13 and the transmission system. However, in order to simplify the explanation, the modularity discussed above is demonstrated between the two solar panels of the single axis solar tracking module 15. It should be said however, that modularity is in fact achieved when connecting two adjacent modules, and their connection is done as illustrated in this FIG. 2, mutates mutandis .

[0061] As depicted in the example illustrated in FIG. 2, protrusion 11 is located at the end of part 12 of the thin rod. Part 12 with its protrusion 11 has a polygonal cross section, e.g. , a hexagonal cross section, and is configured to be inserted into the other part of the rod, part 13, (or the rod of the neighboring single axis solar tracking module, as the case may be) . Rod part 13 has also a hexagonal cross section, but unlike part 12, instead of having a protrusion such as element 11, there is a cavity within part 13, which matches the dimensions of protrusion 11, to enable forming a male-female connection, when inserting protrusion 11 into the cavity. Thus, when rod part 12 and its protrusion 11 rotate while following the solar irradiation, they force the connected part 13 to rotate with them.

[0062] As will be appreciated by those skilled in the art, such as connection between two adjacent single axis solar tracking modules is a detachable connection which is rather useful when carrying out repair or maintenance operations of the single axis solar tracking modules. This also allows a very easy way to customize the total length of a row of single axis solar tracking modules at any given time.

[0063] The ability to use any number of these solar modules is also beneficial for providing the ability to use different motors, depending the length of the combined rods' parts, the respective parts 11, 12, and 13 of the solar tracking modules used, as required when installing a row of such modules and especially in a solar field that has a non-uniform topography.

[0064] The photovoltaic panels are rotated by the combined rod, using in this example few gear wheels 111, 112, 113, 114 and a final gear wheel 14. The latter gear wheel is attached to the support frame of the solar panels that belong to the single axis solar tracking module 15.

[0065] As explained above in connection with FIG. 1, beam 16 supports single axis solar tracking module 15 and provides rigidity of the structure. Beam 16 has a support pillar 17, which holds one or more single axis solar tracking modules at a required distance above the surface .

[0066] Pillars 17 may be supplied at the solar field site as part of the tracking system that comprises a plurality of single axis solar tracking modules. In the alternative, instead of using pillars 17, objects that are already installed at the solar field site can be used for the single axis solar tracking modules to be attached (e.g. , a fence, etc. ) to them. Thus, even if pillars 17 are used, since they are not a part of the single axis solar tracking modules, there is no need to have a number of pillars 17 that match the number of the single axis solar tracking modules 15, as long as the structure rigidity provided by beam 16 is sufficient to support the single axis solar tracking modules 15 that are installed between two adjacent pillars 17.

[0067] One of the advantages provided by the solution of the present invention is that different parts are used to provide the rotation of the solar panels of the system while other parts are used to provide the support for the system. Hence, in certain cases, there is an option to refrain from using beam 16 altogether and instead having a rigid enough post (vertical elements 18) for every single axis solar tracking module, where each vertical element 18 is attached to a respective single axis solar tracking module, which directly supports the rotation axis of the single axis solar tracking modules and the respective solar panels associated therewith.

[0068] In such systems, support beam 16 may be eliminated altogether, or if it exists, it would preferably be located far away, at the lower part of the system, and is obviously not part of the rotation action. The fact that these designs do not rely on a beam that undergoes rotational movement, makes the tracking systems very flexible to implement orientational changes in the rotation mechanism, which is rather a problem in the prior art systems.

[0069] One the other hand, the advantage of having different parts used to provide the rotation of the solar panels of the system while other parts are used to provide the support for the system, might create a challenge of supporting the frame with the solar panels attached to it, while having it rotated. To overcome this issue, final gear wheel 14 may be constructed in such a way that it would form a part of the solar panels support structure, but yet will be large enough to serve as a rotatable element that is mounted on the stationary support structure along a horizontal rotational axis. In other words, final gear wheel 14 may ensure the existence of a large enough distance between the beam and the rod elements. Therefore, the use of final gear wheel 14 as an integral part of the solar panels support structure enables the solar panels to be mounted directly on the transmission system without having to use any mediators therebetween. Consequently, the panels may be installed in a frameless mode.

[0070] Moreover, due to the fact that final gear wheel 14 is mounted on the solar panels frame, it presents a meaningful advantage when the sites used for the installation of such a solar field is a roof, a green house, buildings, fences, walls and the like.

[0071] FIG. 3 demonstrates a case where element 11 can be used for connecting two single axis solar tracking modules, where each of these two modules has a different orientation than the other, yet the combination can easily be operated by using the same motor and rods configuration. However, when installing such a combination, it is preferred that a flexible joint be used between two solar tracking modules. In this case, element 11 (or elements 12 and 13 of FIG. 1, at very specific locations) may be replaced for the sake of movement flexibility with a device comprising two or more connected sections each having a different orientation. In this specific case, the polygon shape of element 11 has a structure that enables the required functionality, and therefor in spite of small changes in the rods' orientation, the rotation remains as explained before along the non-linear rod shown in the FIG.

[0072] Now, as explained above, the solution provided by the present invention relies on using a long thin rod for operating a plurality of single axis solar tracking modules, serially connected to each other. Although, the need to invest forces in order to rotate the plurality of solar panels together is partially resolved by splitting long trackers' chains into shorter chains, still, the problem of handling large torques and moments that may result from the single axis solar tracking module own weight, wind and weather conditions, should be addressed. Such torques are intensified once the single axis solar tracking module' panels are not horizontal and rotated, and these torques are at their peak when the single axis solar tracking module is at the start the backtracking. In the extreme case, the single axis solar tracking module is positioned normal (vertical) to the ground surface. One way of overcoming the problem is by using a transmission system as shown for example in FIG. 2, that comprises gear elements 111, 112, 113 and 114 which serve together as a gears' combination that provides the required transmission ratio. Having a high transmission ratio minimizes the effect of the forces that might be generated due to the wind blowing on the solar panels, Thus, minimizing the need to use dumpers that exists in prior art systems. The transmission system can also compensate for torque generated due to the position of element 14. FIG. 5 illustrates a situation whereby the rotation of the final gear element 14 in the transmission system is temporarily positioned very close to the panels' center of mass. However, because the center of the final gear wheel 14 and panels center of mass may not always coincide, in such a case the transmission system may further include an additional shift that can reduce the distance between the two axes. However, it should be noted that such a shift should be proportional to the angle of the final gear wheel' s rotation. FIG. 4 presents a solution for overcoming topography problems created when using of slanted roofs. Because of the narrow profile of the rod used as the rotational axis and the fact that it is separated from the wide support structure, a number of solutions may be applied. For example, using a flexible shaft coupling and universal joint such as: "Pin and Block", "Needle bearing", "Ball and socket", or Geared solutions. It can be a single U- joint where angular offset is needed or a double U-joint for addressing parallel offsets needs. It is very clear that both operating angle and the mechanism are much easier to implement than if a heavy, wide, and large beam were to be used in these cases. Preferably, a rod that may be used in accordance with the present invention is 10-35mm in diameter.

[0073] Because of the use of completely different parts for the rotational tasks (elements 12 and 13) and for the structure stability functionality (element 16) , the solution provide by the present invention enables the use of a relatively thin rod for the rotation while having the support rigid and wide beam 16 located away from the solar panels. Having such a configuration, results in that there is no substantial shadowing adverse effect due to the beam, on the back radiation reflected from the ground, and a high performance is achieved while using solar panels and especially in the case that bifacial solar panels are used.

[0074] According to some embodiments of the disclosure, when the distance between supporting beam 16 and the solar panels is big enough (for example at least module width) it is possible to achieve by using the present invention solution, a solar panel rotation up to about 90 degrees, because there is no obstruction to their movement by the beam. Such a feature is very useful for example when placing the single axis solar tracking modules onto a fence, or using a row of these solar tracking modules as a fence by itself. Illustration of such a case is exemplified in FIG. 5.

[0075] As previously explained, the system described hereinabove is suitable to implement solar backtracking technique in order to avoid row to row shading, while allowing as little as possible deviation from the true tracking angle, thereby obtaining an improved performance of the solar field. Such an improved performance is achieved by positioning the rows of the solar tracking modules in such a way that the shadow casted from the top edge of one row is exactly tangent to the bottom edge of the row behind it. In solar fields populating dense rows of solar tracking modules, there are many hours during the day that the shadow casted on the ground by the solar photovoltaic panels covers the whole area underneath these panels. The backtracking mode of operation enables achieving a good energy yield while still using a dense panel coverage of the area available for the solar field.

[0076] FIG. 6 exemplifies the novel concept of implementation of a solar backtracking mode. According to this example, a very thin pole 22 which extends away from the single axis solar tracking module 15, is used, a pole which is configured to cast as little shadow as possible. A radiation sensor 21 is attached to this pole 22. As may be seen from this FIG. , the single axis solar tracking module may follow a somewhat different tracking scheme from a pure solar tracking scheme, so that solar rays may penetrate in between the panels even in cases where shadow starts to be casted on the radiation sensor 21. A complete shadowing may be avoided and extra sun time may be used during which sun rays will pass between the solar tracking modules, thereby capturing additional solar radiation that would reach the bottom side of the bifacial panel, without extending the distance between the rows of the solar tracking modules. By implementing the above, an additional significant benefit is achieved, namely, enabling extension of the number of hours during the day, in which the system can be used effectively. Enabling the extension of the solar radiation hours also improves growth of agricultural crops at the same area where the solar field is installed, thereby enabling effective dual-purpose usage of that area.

[0077] According to an embodiment of the invention, the sensor applied to sense the radiation can be positioned on the ground or at any location that is not physically connected to the single axis solar tracking module. Such a situation might significantly limit the angular tracking range to a very minimal rotation, and consequently might cause the panels to rotate near vertical angles (for example within a range of ±30 degrees around the direction normal to the ground) . However, such an option is very attractive for implementation on vertical fences or agriculture fields, in which the shadowing cover ratios must be fixed or at least well controlled. Therefore, a method utilizing a remote sensor in a solar field that operates while relying on a backtracking technique, provides a solution for solar energy collection while using vertical PV panels, and for denser alternative for sparse periods in the cases of single axis solar tracking modules where dual land usage is needed.

[0078] In addition, FIG. 6 illustrates a further embodiment, wherein a wind sensor element 23 is implemented. According to this embodiment, when the wind reaches a pre-defined threshold, a signal is generated by wind sensor 23 which in turn triggers an action to be taken which results in that the photovoltaic panels are brought to a horizontal position or to a perpendicular position, if the wind direction is such that when the photovoltaic panels are brought to a perpendicular position, they will be positioned in parallel to the wind direction. Wind sensor 23 may be located at any one of many locations in the solar field of the photovoltaic panels' arrays and it is likely that only few or even one wind sensor will be required for the whole a solar field.

[0079] Recently, the use of agricultural fields that are co-located with solar fields has been discussed more intensively. However, as may be seen in FIG. 7, one of the problems associated with this dual usage of the ground area is that there is a need to install the rows of the solar trackers far enough from each other in order to have the agricultural crops between these rows. But, by doing that, the solar backtracking mode will come into play for quite a few hours of the day (not only near sunset and sunrise) , which in turn might lead to the situation that the agriculture corps will be partially shadowed for part of the day and illuminated for the other part of the day, while other parts of the field will not be shadowed at all. The solution provided is basically using a two levels field, by mounting the solar tracking modules high enough, constituting the upper level whereas the bottom level is applied for the agricultural crops, so that both solar tracking modules and the agricultural crops will share the sun radiation throughout most of the hours during the day.

[0080] As may be seen from this FIG. this solution requires spacing the rows of the solar tracking modules, apart. Obviously, when using prior art solutions, this requirement leads to the restriction on the number of solar tracking modules that can be installed per area unit of the field (i.e. , the density of installed photovoltaic panels) .

[0081] The solution provided by the present invention, backtracking configuration, as already shown and discussed in connection with FIG. 6, overcomes this constrain by allowing smaller spaces between the columns of single axis solar tracking modules, while still allowing radiation to penetrate in between these columns by controlling the rotation angular range of the single axis solar tracking modules.

[0082] FIGs. 8A and 8B illustrate the implementation of the single axis solar tracking modules of the present invention, on sideroad fences. FIG. 8A illustrates the solar tracking modules position at about noon time, whereas FIG. 8B illustrates the solar tracking modules position during morning or evening times.

[0083] FIG. 9 demonstrates the use of the single axis solar tracking modules in accordance with an embodiment of the present invention implemented for greenhouses' applications .

[0084] FIGs. 10 illustrate another embodiment of the present invention, by which the single axis solar tracking modules of the present invention are installed in a two levels' configuration, so as to form a lower PV array and an upper PV array, where both these arrays have the same recurrence of the solar tracking modules. FIG. 10A illustrates the morning case where the sun rays can pass in between the solar tracking modules of the upper array and irradiate the solar tracking modules of the lower array. FIG. 10B illustrates the orientations of the upper array and the lower array at the middle of the day case, whereas FIG. 10C illustrates orientations of the upper array and the lower array in between the two cases illustrated in FIGs 10A and 10B. As may be seen from these FIGs. , sun rays that passed between the single axis solar tracking modules of the upper level, reached the single axis solar tracking modules of the lower level. Such an embodiment is very useful particularly for areas where there is a need to upgrade already installed PV arrays. The additional PV arrays can be installed as an upper-level array at a sufficient height above ground, while the already installed PV array can be used as the lower-level array where the effective PV panels will be those that are located underneath the spaces that will be left between the single axis solar tracking modules of the upper level. The inclination angle of the single axis solar tracking modules of the lower-level array may be changed in conformity with the solar / shadow conditions that this array is subjected to. Such changes may be implemented by using the transmission system that rotates the single axis solar tracking modules of the lower level (e.g. , element 14 in FIG. 2) , and in order to provide the control of the transmission system of the lower array with the information required to affect such changes, radiation sensors 21, which may be located as depicted in FIG. 10A at the edge of the panels, or independently of the panels (e.g. , ground installation) , or at any combination of the two installation options, are used.

[0085] FIG. 11 illustrates an embodiment, by which the transmission system of the single axis solar tracking module is further configured to compensate for a distance extending between a center of the transmission system's final (last) gear wheel 1101 and between a center of mass of the at least two solar panels 1103, by using a shift movement being proportional to an angle generated between the single axis solar tracking module and the ground, by the transmission system's final gear wheel rotation. Such proportional shift can be achieved by using a further, smaller grooved wheel 1105 which is positioned concentrically to the (outer) final gear wheel. This smaller grooved wheel may be attached to a linear (or nearly linear) grooved rod 1107 so that any rotational movement of the final gear wheel will cause a proportional linear shift. The ratio between the last gear wheel and the additional smaller wheel, that is responsible for the linear shift transfer, can be adjusted as depicted in FIG. 12 by affecting a 90° degrees panel shift, so that the linear shift will move the center of mass of the at least two solar panels, exactly above the rotation axis, thereby eliminating the adverse impact of the torque generated due to the at least two solar panels weight.

[0086] It is to be understood that the present invention has been described using non-limiting detailed descriptions of embodiments thereof that are provided by way of example and are not intended to limit the scope of the invention. It should be understood that features and / or steps described with respect to one embodiment may be used with other embodiments and that not all embodiments of the invention have all of the features and / or steps shown in a particular figure or described with respect to one of the embodiments. Variations of embodiments described will occur to persons of the art.

[0087] It should be noted that some of the above-described embodiments describe the best mode contemplated by the inventors and therefore include structure, acts or details of structures and acts that may not be essential to the invention and which are described as examples. Structure and acts described herein are replaceable by equivalents which perform the same function, even if the structure or acts are different, as known in the art. Therefore, the scope of the invention is limited only by the elements and limitations as used in the claims. When used in the following claims, the terms "comprise", "include", "have" and their conjugates mean "including but not limited to" .

Claims

CLAIMS1. A single axis solar tracking module, comprising: at least two solar panels rotatably coupled to a rotational axis, wherein said rotational axis comprises a rod extending laterally along the at least two solar panels, wherein a first part of said rod extends laterally along a first of the at least two solar panels, and comprises a protrusion that matches a cavity starting from an edge of the second part of said rod, and wherein said second part of the rod extends laterally along a second of the at least two solar panels that is located adjacent to the first solar panel, so that by inserting said protrusion into said cavity, the first and second solar panels are attached to each other thereby obtaining a combined rod, and wherein said combined rod is used as the solar panels' rotational axis; a frame, for mounting the at least two solar panels thereat ; a transmission system configured to rotate said frame of the single axis solar tracking module with the at least two solar panels mounted thereat.

2. The single axis solar tracking module of claim 1, configured to be associated with a structure beam located away from the rotational axis, at a distance which is equal to at least half of the solar tracking module' s width .

3. The single axis solar tracking module of claim 1, further comprising a motor configured to rotate the single axis solar tracking module by using the transmission system thereof.

4. The single axis solar tracking module of claim 1, wherein at least one of said two solar panels is a bifacial photovoltaic panel.

5. The single axis solar tracking module of claim 1, further comprising a static beam structure.

6. The single axis solar tracking module of claim 1, wherein said protrusion and said cavity have a polygonal cross section.

7. The single axis solar tracking module of claim 1, wherein said module is configured to be connected to another such a single axis solar tracking module, by using a flexible joint.

8. The single axis tracking module of claim 1, wherein said frame is configured to be attached to an object that has already been installed at a site where said single axis solar tracking module is about to be mounted.

9. The single axis tracking module of claim 1, further comprising a radiation measuring sensor.

10. The single axis tracking module of claim 8, wherein said single mode tracking module is configured to operate also in a solar backtracking mode.

11. The single axis tracking module of claim 1, configured to operate by enabling the two solar panels to reach up to ± 90° position relative to the ground.

12. The single axis solar tracking module of claim 1, wherein the transmission system is further configured tocompensate for a distance extending between a center of the transmission system's final gear wheel and between a center of mass of the at least two solar panels, by using a shift movement being proportional to an angle generated between the module and the ground.

13. A system comprising a plurality of single axis tracking modules of claim 1, wherein part of the plurality of single axis tracking modules are installed and operative above the remaining single axis tracking modules belonging to said plurality of single axis tracking modules.

14. A method for use in a solar system which is configured to operate in both forward tracking and backtracking, which comprises a plurality of single axis tracking modules, wherein said method comprises a step of utilizing a radiation measuring sensor installed remotely from one or more of the single axis tracking modules.

15. The method of claim 14, wherein said method further comprising a step of utilizing a sensor installed underneath the one or more single axis tracking modules' plane to limit angular tracking range of said one or more single axis tracking modules, to a minimal rotation.

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