Patent Publication Number: US-2012023728-A1

Title: Apparatus And Methods For Transporting Large Photovoltaic Modules

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 61/357,714, filed Jun. 23, 2010. 
    
    
     BACKGROUND 
     Embodiments of the present invention generally relate to apparatus and methods of moving photovoltaic modules. Specific embodiments pertain to dollies for moving photovoltaic modules and methods of moving photovoltaic modules and assembling solar farms. 
     Thin film photovoltaic modules, also called solar modules, are made up of a plurality of individual thin film solar cells, or photovoltaic cells, connected in series. Fully assembled photovoltaic modules, especially large size modules, are heavy and can be difficult to install. 
     For example, the size and mass of 5.7 m 2  photovoltaic modules are too great for efficient and safe installation by human labor alone, which is the current installation method for smaller photovoltaic modules. While modules of this size can be installed by human labor alone, it is not particularly efficient and can easily result in an unacceptable amount of module breakage. To date, non-manual installation has generally required the use of specialized equipment, specifically a large crane or boom truck. Three main issues exist with these modes of installation: (1) the terrain and soil conditions (e.g., mud) may make the use of large equipment difficult; (2) in certain economic areas (e.g., China) the total installation cost using specialized equipment is much higher than if done by manual labor; and (3) for rooftop installations, the crane must be very large and all movements conducted blindly (via radio), increasing installation times and making rooftop installation of large modules less attractive. 
     Therefore, there is a need for apparatus and methods for safely transporting and placing modules in a solar farm which minimizes the use of large equipment and makes smart, effective use of manual labor. 
     SUMMARY OF THE INVENTION 
     One or more embodiments of the present invention are directed to a dolly, or dollies, for moving a planar photovoltaic module having a plurality of spaced rails supporting a back side of the photovoltaic module. The dolly comprises an elongate base section and a support section. The elongate base section has an axial length and a first plurality of rollers mounted along the axial length of the elongate base section. The support section is movably coupled with the elongate base section such that the support section can be moved upwardly and downwardly to raise and lower the photovoltaic module. The support section includes a plurality of cradles spaced at a predetermined distance so that each cradle supports the spaced rails. The support section further includes a lifting mechanism including a lifting member operatively engaged with the base section and the support section to raise and lower the support section. 
     In some embodiments, the elongate base section further comprises a second plurality of rollers mounted along the axial length perpendicular to the first plurality of rollers. In specific embodiments, the plurality of rollers are wheels. 
     The elongate base section of detailed embodiments has a top, a front face and a back face defining an inverted elongate u-shape with an open bottom and a cavity therein. In specific embodiments, the first plurality of rollers are wheels located within the cavity and mounted to the elongate base section, a portion of each of the first plurality of wheels projecting from the open bottom of the cavity of the elongate base section. According to some embodiments, each of the wheels are attached to the elongate base section with an axle attached to the front face and the back face of the elongate base section, the wheels being freely rotatable about the axle. 
     The lifting mechanism of some embodiments further comprises a hinge assembly in contact with a face of the elongate base and a lever arm operatively connected to the hinge assembly so that the lever arm can be moved in an axial and radial direction with respect to the hinge assembly. Moving the lever arm axially does not cause rotation of the hinge assembly. Moving the lever arm radially causes rotation of the hinge assembly and movement of the lifting member in a direction to raise or lower the support section. In specific embodiments, the lifting mechanism further comprises a lever bracket on a face of the elongate base positioned to allow the lever arm to be placed in the lever bracket. 
     In specific embodiments, the lifting member is operatively engaged with the base section and the support section by an eccentric cam which projects from the elongate base. The eccentric cam operable to change projection from a minimum projection to a maximum projection. 
     In some embodiments, the first plurality of rollers comprises two proximal wheels positioned proximally of a center point in the elongate base and two distal wheels positioned distally of the center point in the elongate base. 
     The support section of one or more embodiments further comprises at least one connection hole including a captive knob therein. The captive knob is adapted to cooperatively interact with a hole in the spaced rails on the back side of the photovoltaic module. 
     In detailed embodiments, the elongate base section is made of galvanized steel with a thickness of at least about 1.5 mm. 
     Additional embodiments of the invention are directed to dolly kits for moving a planar photovoltaic module having a plurality of spaced rails supporting a back side of the photovoltaic module. The dolly comprises an upper rail dolly and a lower rail dolly. The upper rail dolly comprises an elongate base section and a support section. The elongate base section has an axial length and a first upper plurality of rollers mounted along the axial length of the elongate base section and a second upper plurality of rollers mounted along the axial length of the elongate base in a plane perpendicular to the first plurality of rollers. The support section is movably coupled with the elongate base section such that the support section can be moved upwardly and downwardly to raise and lower the module. The support section includes a plurality of cradles spaced at a predetermined distance so that each cradle supports the spaced rails. The support section further includes a lifting mechanism including a lifting member operatively engaged with the base section and the support section to raise and lower the support section. The lower rail dolly comprises an elongate base section and a support section. The elongate base section has an axial length and a lower plurality of rollers mounted along the axial length of the elongate base section. The support section is movably coupled with the elongate base section such that the support section can be moved upwardly and downwardly to raise and lower the module. The support section includes a plurality of cradles spaced at a predetermined distance so that each cradle supports the spaced rails. The support section further includes a lifting mechanism including a lifting member operatively engaged with the base section and the support section to raise and lower the support section. In detailed embodiments, one or more of the first upper plurality of rollers, the second upper plurality of roller and the lower plurality of rollers are wheels. 
     Further embodiments of the invention are directed to methods of mounting a photovoltaic module on a support structure having an upper rail and a lower rail, the upper rail having a horizontal rail surface and vertical rail surface and the lower rail having a horizontal rail surface. The methods comprise attaching an upper rail dolly to spaced rails on the back of the photovoltaic module. The upper rail dolly has vertically aligned rollers and horizontally aligned rollers. The upper rail dolly has a cradle for contacting the spaced rails on the back of the photovoltaic module. A lower rail dolly is attached to the spaced rails of the photovoltaic module. The lower rail dolly has vertically aligned rollers and a cradle for contacting the spaced rails on the back of the photovoltaic module. The upper rail dolly is placed on the upper rail of the support structure so the vertically aligned rollers contact the horizontal rail surface and the horizontally aligned rollers contact the vertical rail surface. The lower rail dolly is placed on the lower rail of the support structure so that the vertically aligned rollers contact the horizontal rail surface of the support structure. The cradle of the upper rail dolly and the cradle of the lower rail dolly are lifted to lift the photovoltaic module so that the spaced rails on the back of the photovoltaic module do not contact the support structure. The photovoltaic module is moved along the upper rail and lower rail of the support structure to a mounting location. The cradle of the upper rail dolly and the cradle of the lower rail dolly are lowered to lower the photovoltaic module so that the spaced rails on the back of the photovoltaic module are in contact with the upper rail and lower rail of the support structure. The photovoltaic module is fixed to the support structure. 
     Detailed embodiments further comprise suspending the photovoltaic module to allow access to the spaced rails on a back of the photovoltaic module and attaching one or more of the upper rail dolly and the lower rail dolly to the spaced rails before placing the one or more dolly on the support structure. In specific embodiments, the photovoltaic module is suspended with a vacuum frame. In specific embodiments the vacuum frame is held by a portable jib boom. 
     Some embodiments further comprise removing the upper rail dolly from the upper rail of the support structure and removing the lower rail dolly from the lower rail of the support structure after the photovoltaic module is fixed to the support structure. 
     According to one or more embodiments, the photovoltaic module comprises a plurality of small solar modules that are assembled into a larger array. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  shows a depiction of an aerial view of a solar farm including crane locations and operable radii for each crane location according to a prior art process for mounting photovoltaic modules; 
         FIG. 2A  is a side view of a photovoltaic support structure; 
         FIG. 2B  is an expanded side view of the top end of a photovoltaic support structure taken along section  2 B of  FIG. 2A . 
         FIG. 3  is a side view of a lower rail dolly in accordance with one or more embodiments of the invention; 
         FIG. 4  is a side view of an upper rail dolly in accordance with one or more embodiments of the invention; 
         FIG. 5  is a perspective view of an upper rail dolly in accordance with one or more embodiments of the invention; 
         FIG. 6  is an end view of a an upper rail dolly in accordance with one or more embodiments of the invention placed on the expanded side view of the top end of a support structure taken along section  2 B of  FIG. 2A ; 
         FIG. 7  shows a perspective view of an upper rail dolly in the movable position in accordance with one or more embodiments of the invention; 
         FIG. 8  shows a perspective view of an upper rail dolly in a mounting position in accordance with one or more embodiments of the invention; and 
         FIG. 9  shows a schematic of a loading station concept according to one or more embodiments of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Before describing several exemplary embodiments of the invention, it is to be understood that the invention is not limited to the details of construction or process steps set forth in the following description. The invention is capable of other embodiments and of being practiced or being carried out in various ways. 
     As used in this specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents unless the context clearly indicates otherwise. For example, reference to a “cell” may also refer to more than one cells, and the like. 
     The terms “photovoltaic module” and “solar module” are used to describe a device made up of a plurality of individual photovoltaic cells suitable for converting light into electricity. 
       FIG. 1  shows a sketch of an aerial view of a small solar farm  100  containing twelve rows  110  of photovoltaic modules  120 . A typical process for mounting these modules  120  involves a four-man team working with a crane  130 . The crane  130  must be driven through the farm  100 , sweeping back and forth, to install modules  120  along each row  110 .  FIG. 1  shows four crane positions with the operable radius  140  for each position shown with a circle. To cover all areas of the solar farm  100 , it is necessary for the crane positions to be such that the operable radius  140  of one position overlaps with an adjacent position, as shown in the Figure. This process is very time consuming as it requires the crane to be routinely repositioned to access a different area of the solar farm. Additionally, the terrain and soil conditions can make moving large equipment through the farm very difficult or sometimes impossible. Deep mud or soft sand are two examples of poor soils that may prohibit crane movement. It is also an expensive process because it requires four people and a mobile crane unit. 
     Although not exactly to scale, the solar farm  100  of  FIG. 1  has twelve rows with each having an approximate length of 50 meters. A typical 1 MW solar farm has more than 40 rows with each being larger than about 100 meters in length. Obviously, to cover a 1 MW solar farm, a crane would need to be relocated many times over potentially rough terrain and soil, an inefficient and costly proposition at best. 
       FIG. 2A  shows a common support structure  200  used in many solar farms. The support structures include a ground penetrating post  210  with angled supports  220  for holding the solar modules. The ground penetrating post  210  may be made from galvanized steel and roll formed. The angled supports  220  are connected to the ground penetrating post  210  by bolts  230  positioned through slots (not shown) in either the post  210  or angled supports  220 . The slots allow the angle of the angled supports  220  to be changed depending on the location and needs of the solar farm. 
     The angled supports  220  include a zee purlin cross supports, also referred to as z-track  240 . An upper rail  250  is located on the top end and a lower rail  260  is located on the bottom end of the angled supports  220 .  FIG. 2B  shows an expanded view of the top end  250  of the angled support  220 . A z-track  240  is shown attached to the top end  250  of the angled support  220  using a pair of bolts  270 . These bolts  270  are optional and can be replaced by any suitable connection means. The z-track  240  includes a horizontal rail surface  280  and a vertical rail surface  290 . It can be seen from  FIG. 2B  that the horizontal rail surface  290  is not perfectly horizontal, but at an angle approximately equal to that of the angled support  220 . As used in this specification and the appended claims, the term “horizontal rail surface” means the lower z-track  240  surface that is about collinear with angled support  220 , as shown in  FIG. 2B . It can also be seen from  FIG. 2B  that the vertical rail surface  290  is not perfectly vertical, but an angle approximately 90° from that of the angled support  220 . As used in this specification and the appended claims, the term “vertical rail surface” means the portion of the z-track  240  that is substantially perpendicular to the long axis of the angled support  220  and/or substantially perpendicular to the horizontal rail surface  280 , as shown in  FIG. 2B . 
     One or more embodiments of the invention are directed to photovoltaic module dollies that can use the z-tracks  240  of existing support structures  200  as a rail for sliding a module.  FIGS. 3-8  show representative embodiments of a module dolly  300  and use. These embodiments are merely illustrative and should not be taken as limiting the scope of the invention. The Figures show various embodiments of a dolly  300  for moving a substantially planar photovoltaic module  302  are shown. As used in this specification and the appended claims, the term “substantially planar” means that the photovoltaic module is reasonably flat, i.e., not so non-planar that the module does not function as intended. The photovoltaic modules  302  for use with some embodiments have a plurality of spaced rails  304  supporting a back side of the photovoltaic module  302 . Specific embodiments of the invention are intended for use with photovoltaic modules  302  having four spaced rails  304 . 
     The dolly  300  includes an elongate base section  306  having an axial length L and a first plurality of rollers  308  mounted along the axial length L of the elongate base section  306 . A support section  312  is movably coupled with the elongate base section  306  such that the support section  312  can be moved upwardly and downwardly to raise and lower the photovoltaic module  302 . The support section  312  includes a plurality of cradles  314  spaced at a predetermined distance so that each cradle  314  supports a spaced rail  304 . The support section  312  further includes a lifting mechanism  316  including a lifting member operatively engaged with the base section  306  and the support section  312  to raise and lower the support section  312 . 
     In specific embodiments, the elongate base section  306  further comprises a second plurality of rollers  322  mounted along the axial length L in a direction perpendicular to the first plurality of rollers  308 . 
     Embodiments of the invention include rollers which can be any number of suitable roller devices. Suitable examples include, but are not limited to, wheels and ball bearings. In detailed embodiments, one or more of the first plurality of rollers  308  and second plurality of rollers  322  are wheels. In specific embodiments the wheels have a diameter greater than about 30 mm. In other embodiments, the wheels have a diameter about 40 mm. The embodiments shown in  FIGS. 3 through 8  use wheels for both the first plurality of rollers  308  and the second plurality of rollers  322 . 
     The elongate base section  306  can be any suitable shape. In specific embodiments, as best shown in  FIGS. 5 to 7 , the elongate base section  306  has a top  324 , a front face  326  and a back face  328  defining an inverted elongate u-shape with an open bottom and a cavity  322  therein. In some detailed embodiments, the first plurality of rollers  308  are located in the cavity  322  and are mounted to the elongate base section  306  and the bottom portions project from open bottom of the cavity  332  in the elongate base section  306 . In some embodiments, the top portion of the first plurality of rollers  308  may extend through openings  334  in the top  324  of the elongate base section  306 , as shown in  FIG. 5 . The openings  334  in specific embodiments are positioned over the outside rollers only. These openings  334  may allow the outside rollers to move upwardly when the dolly is crossing gaps in the support structures  200 . 
     In detailed embodiments, each of the first plurality of rollers  308  are wheels which are attached to the elongate base section  306  with an axle  336  which is attached to the front face  326  and the back face  328  of the elongate base section  308 . The first plurality of rollers  308  being freely rotatable about the axle  336 . 
     In one or more embodiments of the invention, the lifting mechanism  316  further comprises a hinge assembly  338  in contact with either the front face  326  or the back face  328  of the elongate base section  306 . A lever arm  342  may be operatively connected to the hinge assembly  338  so that the lever arm  342  can be moved in an axial and radial direction with respect to the hinge assembly  338 . Referring to  FIG. 6 , movement of the lever arm  342  axially means that the lever arm  342  moves along about the same axis as the second plurality of rollers  322 . Axial movement of the lever arm does not cause rotation of the hinge assembly  338 . Movement of the lever arm  342  radially causes the hinge assembly  338  to rotate, causing movement of the lifting member  318  in a direction to raise or lower the support section  312 . This combination of axial and radial motion allows the lever arm  342  to be pressed against the front face  326  of the elongate base section  306  when not actively being used to ensure that the lever arm  342  is not in the way. When not in active use, the lever arm  342  may be placed in a lever bracket  344  attached to the front face  326  of the elongate base section  306 . 
     When needed, the lever arm  342  can be moved axially by any amount from about 0° to about 180°, allowing radial movement of lever arm  342  to be transferred to the hinge assembly  338  and cause the hinge assembly  338  to rotate. In specific embodiments, the lever arm  342  can be moved axially less than about 90° relative to the front face  326  of the elongate base section  306 . In other embodiments, the lever arm  342  can be moved axially less than about 80°, 70°, 60°, 50°, 45°, 40° or 30° relative to the front face  326  of the elongate base section  306 . 
     In specific embodiments, the lifting member  318  is operatively engaged with the elongate base section  306 , and the support section  312  is an eccentric cam. This cam, which can be seen in  FIGS. 3 and 4 , projects from the elongate base section  306  to a varying degree depending on the position of the lever arm  342 . Movement of the lever arm  342  causes the lifting member  318  to change projection from a minimum projection to a maximum project. In detailed embodiments, the lifting member  318  provides a lift travel of about 35 mm. In various embodiments, the lifting member  318  or eccentric cam provides a lift travel of greater than about 20 mm, 25 mm, 30 mm, 35 mm or 40 mm. In specific embodiments, the lifting member  318  is an eccentric cam. In one or more embodiments, the lifting member  318  includes a pneumatic or hydraulic cylinder, ball screw, cable assembly with linear guides, levers and combinations thereof. This preceding list of lifting members are merely illustrative and should not be taken as limiting the scope of the invention. 
     The movement from the minimum projection to the maximum projection is exemplified in the embodiments shown in  FIGS. 7 and 8 .  FIG. 7  shows a dolly  300  supporting a photovoltaic module  302  in the in the movable position. The support section  312  of the dolly  300  is in the raised position which holds the module  302  off of the angled supports  220  and the z-track  240 . The lever arm  342  is positioned toward the distal end of the dolly  300 , shown as the right side of the dolly in  FIG. 4 . With the lever arm  342  in this position, the hinge assembly  338  is rotated to a position where the lifting member  318  is in a position of maximum projection. In some embodiments, the lever arm  342  rests in a lever bracket  344 , which helps prevent the weight of the module  302 , i.e., pressure applied to the lifting member  318 , from causing or forcing the lifting member  318  into a lowered position causing the hinge assembly  338  to rotate. It should be understood that the direction of the lever arm  342  does not need to be distally directed to cause the lifting member  318  to be in the position of maximum projection, and can be reversed, or in other configurations. 
       FIG. 8  shows the dolly  300  of  FIG. 7  in the mounting position. The dolly  300  has been moved along the z-track  240  to the desired mounting position. The photovoltaic module  302  has been attached to the angled supports  220  and the support section  312  is no longer in contact with the spaced rails  304 . The lever arm  342  is directed toward the proximal end of the dolly  300  in  FIG. 8 . As there is no pressure applied to the support section  312  in this position, there is little reason for a lever bracket  344  on this side. However, in some embodiments there is a lever bracket  344  on the side of the dolly  300  which represents the lowered position for the support section  312 . The lever bracket  344  in these cases can be used to ensure that the lever arm  342  remains safely out of the way during movement of the dolly  300 . With the support section  312  in the lowered position, there is a gap between the support section  312  and the spaced rails  304  on the module  302 . The gap allows the dolly  300  can be removed from the z-track  240  without affecting the position of the module  302  as the module  302  has already be affixed into place on the support structure  200 . In detailed embodiments, the gap is up to about 10 mm. In specific embodiments, the gap is in the range of about 5-6 mm. In various embodiments, the gap is greater than about 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm or 9 mm. 
     The support section  312  of some embodiments is further supported by at least one shaft  356 . The at least one shaft  356  can be connected to the support section  312  by any suitable means. In detailed embodiments, the shaft  356  is threaded into the support section  312 . The at least one shaft  356  may help provide additional lateral support to the dolly  300  helping to prevent the support section  312  from twisting substantially out of alignment with the elongate base section  306 . In specific embodiments, the elongate base section  306  further comprises at least one shaft bracket  358  positioned to cooperatively interact with the shaft  356 . The shaft bracket  358  may also help provide lateral support to the dolly  300  by supporting the shafts  356  which in turn provide support for the support section  312 . 
     In detailed embodiments, as shown in  FIG. 5 , the first plurality of rollers  308  comprises two proximal wheels positioned proximally of a center point in the elongate base section  306  and two distal wheels positioned distally of the center point in the elongate base section  306 . In specific embodiments, the second plurality of rollers  322  comprise two proximal wheels positioned proximally of a center point in the elongate base section  306  and two distal wheels position distally of the center point in the elongate base section  306 . The first plurality of rollers  308  and the second plurality of rollers  322  may be split into groups with individual rollers separated to allow the dolly to pass over small gaps in the z-track  240 . This allows one roller or set of rollers can take the load while the other roller or set of rollers is over the gap. 
     In some embodiments, as shown in  FIG. 4 , the first plurality of rollers  308  comprise two left half wheels positioned to the left of a center point in the elongate base section  306 . The second plurality of rollers  322  may comprise two right half wheels positioned to the right of a center point in the elongate base section  306 . The splitting of the wheels into two sets of two wheels enables the dolly  300  to roll across breaks in the z-track  240  without being dislodged. 
     The wheels can be spaced in any number of configurations. In specific embodiments, where one or more of the first plurality of wheels  308  and the second plurality of wheels  322  are split into two groups of two, the groups are separated by a distance in the range of about 700 to about 1000 mm (measured on centers). In specific embodiments, the groups are separated by a distance of about 860 mm (measured on centers). In some embodiments with the same split design, the two left half (or proximal wheels) and/or the two right half (or distal wheels) are separated by a distance in the range of about 200 mm to about 350 mm (measured on center). In specific embodiments, the distance is about 280 MM. 
     The plurality of cradles  314  in the support section  312  can be any suitable shape for interacting with the spaced rails  304  on the back of the photovoltaic module  302 . The cradles  314  shown in  FIGS. 6-8  are u-shaped recesses in the support section  312  which are sized to cooperatively interact with the spaced rails  304 . In  FIG. 5 , the cradles  314  further comprise wings  354  which extend size of the support section  312  in a direction perpendicular to the axial length L of the dolly  300 . The wings  354  increase the surface area of the spaced rails  304  that the support section  312  contacts. The length of the wings  354  can be adjusted as needed. In some embodiments, the cradles  314  have wings  354  which extend to both sides of the dolly  300 . The larger cradles  314  may provide greater stability and help prevent twisting of the dolly  300  under strain. 
     Additionally, the support section of detailed embodiments includes a retention member. The retention member can be any number of suitable connection mechanisms and are not limited to the mechanisms described here. In some embodiments, the support section  312  includes at least one pin  352  which can be inserted into a hole (not shown) in the spaced rails  304 . The pin  352  can be located in the cradles  314  and helps prevent the module  302  from sliding off of the dolly  300 . 
     To secure the photovoltaic module  302  to the support section  312  of the dolly  300 , some embodiments further comprise at least one connection hole  348  in the support section  312 , or in the cradle  314 . The connection hole  348  may be threaded or unthreaded and may include a captive knob  346  inserted therein. The captive knob  346  may be adapted to cooperatively interact with a hole (not shown) in the spaced rails  304  on the back side of the photovoltaic module  302 . This allows the user to easily secure the dolly  300  to the back of the photovoltaic module  302  without the need for additional tools. 
     The elongate base section  306  and/or the support section  312  can be made of any suitable material, including but not limited to aluminum, steel, galvanized steel, painted or powder coated materials, carbon graphite and high strength aluminum extrusions. In detailed embodiments, the elongate base section  306  and/or the support section  312  are made from steel or galvanized steel. In specific embodiments, the elongate base section  306  and/or the support section  312  is made from a galvanized steel with a thickness of at least about 1.5 mm. In various embodiments, the elongate base section  306  and/or the support section  312  are made from galvanized steel with a thickness of at least about 1 mm, 2 mm, 2.25 mm, 2.5 mm, 2.75 mm or 3 mm. 
     In some embodiments, the elongate base section  306  includes at least one additional riveted stiffener (not shown) to prevent twisting of the dolly  300  under strain from the weight of the photovoltaic module  302 . The at least one stiffener may be used in embodiments where the elongate base section  306  includes an opening, like the cavity  332  previously described. In one or more embodiments, the elongate base section  306  is bolted or welded to provide additional stiffness and/or prevent twisting. 
     Additional embodiments of the invention are directed to dolly kits for moving a planar photovoltaic module. The dolly kits comprise two separate dolly units, an upper rail dolly and a lower rail dolly. Both dollies are designed based on the embodiments previously described. The upper rail dolly, shown in  FIGS. 4-8  includes a first plurality of rollers  308  and a second plurality of rollers  322 . The first plurality of rollers  308  ride along the horizontal rail surface  280  of the z-track  240 , and the second plurality of rollers  322  ride along the vertical rail surface  290  of the z-track  240 . The combination of the first plurality of rollers  308  and the second plurality of rollers  322  provide both vertical and lateral support. The lower rail dolly, shown in  FIG. 3  includes a lower plurality of rollers which are similar to the first plurality of rollers  308  in the upper rail dolly. 
     Further embodiments of the invention are directed to methods of mounting a photovoltaic module  302  on a support structure  200  having an upper rail  250  and a lower rail  260 . The upper rail  250  has a horizontal rail surface  280  and vertical rail surface  290  and the lower rail  250  has a horizontal rail surface which is a mirror image of the z-track on the upper rail  250 . An upper rail dolly, as shown in  FIG. 4 , is attached to spaced rails  304  on the back of the photovoltaic module  302 . The upper rail dolly has a first plurality of rollers  308  which are vertically aligned and second plurality of rollers  322  which are horizontally aligned. The first plurality of rollers  308  may also be referred to as the vertically aligned rollers and the second plurality of rollers  322  may also be referred to as horizontally aligned rollers. The upper rail dolly has at least one cradle  314  for contacting the spaced rails  304  on the back of the photovoltaic module  302 . A lower rail dolly, as in  FIG. 3 , is attached to the spaced rails  304  of the photovoltaic module  302 . The lower rail dolly has vertically aligned rollers and at least one cradle  314  for contacting the spaced rails  304  on the back of the photovoltaic module  302 . 
     The upper rail dolly is placed on the on the upper rail  250  of the support structure  200  so the vertically aligned rollers contact the horizontal rail surface  280  and the horizontally aligned rollers contact the vertical rail surface  290 . The lower rail dolly is placed on the lower rail  260  of the support structure  200  so that the vertically aligned rollers contact the horizontal rail surface  280  of the support structure  200 . Whether the upper rail dolly or the lower rail dolly is placed on the respective rails first is not important and should not be taken as limiting the scope of the invention. In detailed embodiments, the upper rail dolly is placed on the upper rail  250  first. In some embodiments, the lower rail dolly is placed on the lower rail  260  first. In specific embodiments, the upper rail dolly is placed on the upper rail  250  and the lower rail dolly is placed on the lower rail  260  at substantially the same time. 
     The at least one cradle  314  of the upper rail dolly and the at least one cradle  314  of the lower rail dolly are lifted by lifting the support section  312  of the respective dolly  300  to lift the photovoltaic module  302  so that the spaced rails  304  on the back of the photovoltaic module  302  do not contact the support structure  200 . The support sections  312  can be lifted to the elevated position before or after placing the respective dolly onto the respective rail. In some embodiments, the support sections  312  are lifted prior to placing the dollies on the rails. In various embodiments, the supports section  312  are lifted after placing the dollies on the rails. 
     Once both the upper rail dolly and the lower rail dolly have the support sections  312  containing the cradles  314  in the elevated position, the photovoltaic module  302  is moved along the upper rail  250  and lower rail  260  of the support structure  200  to a location where the module  302  will be mounted. The module can then be attached to the support structure  200  by any suitable means. 
     After the photovoltaic module  203  has been affixed to the support structure  200 , the support section  312  including the at least one cradles  314  of the upper rail dolly and the lower rail dolly are lowered. Once the supports sections  312  are in the lowered position, the spaced rails  304  on the back of the photovoltaic module  302  are in contact with the upper rail  250  and lower rail  260  of the support structure  200  and the dollies can be removed. 
     If the support sections  312  are connected to the spaced rails  304  by, for example, a captive knob  346 , the support section  312  is lowered in at least two stages. First the support section  312  is lowered to allow the spaced rails to rest on the support structure  200 . After the module  302  is affixed to the support structure, the support section  312  can be disconnected from the spaced rails  304  and lowered completely. Once completely lowered, the dolly can be removed from the z-track without disturbing the mounted module. 
     In some embodiments, the photovoltaic module  302  is suspended to allow access to the spaced rails  304  on a back of the photovoltaic module  302 . While suspended, one or more of the upper rail dolly and the lower rail dolly are attached to the spaced rails  304  before placing the one or more dolly on the support structure  200 . In specific detailed embodiments, the photovoltaic module  302  is suspended with a vacuum frame. In specific embodiments, the vacuum frame is held by a portable jib boom  900 . 
       FIG. 9  shows a loading station concept in accordance with the various embodiments of the invention. A portable jib boom  900  can be positioned at the end of a row  110  in solar farm  100 . A module shipping rack  902  can be positioned within reach of the jib boom  900 . An individual module  302  can be lifted on the jib boom  900  and the dollies can be attached to the spaced rails  304  on the back. The jib boom  900  can then pivot to allow the dollies to be placed on the rails of the support structure  200 . Once on the rails, the module  302  can be slid down the support structure  200  and affixed in place. In some embodiments, the jib boom  900  is affixed with a vacuum frame (not shown) which allows the individual photovoltaic modules  302  to be easily lifted without damaging the surface. 
     This allows the entire row of the solar farm to be populated with photovoltaic modules without having to relocate the jib boom  900  or the module shipping rack  902 . Depending on the size and reach of the jib boom  900 , more than one row of the solar farm could be populated without needing to relocated the jib boom  900  or the module shipping rack  902 . This will allow 2 or 3 people to install the modules in the entire solar farm with relatively small and portable equipment. Additionally, when relocation of the jib boom  900  is necessary, the jib boom  900  needs to be moved along the edges of the array or through aisleways. These areas are typically leveled and/or compacted for future array service and/or emergency access. Therefore, the jib boom  900  does not need to be moved over potentially rough terrain or through difficult soil conditions. 
     The module dollies supporting the individual module  302  can be pushed through the solar farm by a human. Additionally, the module  302  could be propelled through the farm on the dollies  300  in a variety of ways, including but not limited to, pulley systems and electric motors. In specific embodiments, the dolly  300  is fitted with an electric motor adapted to propel the dolly  300  laden with a module  302  along the length of the z-track  240  in a solar farm. In more specific embodiments, the dolly  300  has an electric motor powered by the solar module  302  being supported by the dolly  300 . 
     The dolly  300  and installation methods have been described with respect to moving and supporting large scale (i.e., 5.7 m 2 ) modules. It should be understood that the dolly  300  and methods are also applicable to small solar panels, especially when the small solar panels have been pre-assembled into a larger array. 
     Reference throughout this specification to “one embodiment,” “certain embodiments,” “one or more embodiments,” “an embodiment,” “one aspect,” “certain aspects,” “one or more embodiments” and “an aspect” means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases such as “in one or more embodiments,” “in certain embodiments,” “in one embodiment,” “in an embodiment,” “according to one or more aspects,” “in an aspect,” etc., in various places throughout this specification are not necessarily referring to the same embodiment or aspect of the invention. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or aspects. The order of description of the above method should not be considered limiting, and methods may use the described operations out of order or with omissions or additions. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other embodiments will be apparent to those of ordinary skill in the art upon reviewing the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.