CA2824032A1 - Solar panel rack system - Google Patents

Description

SOLAR PANEL RACK SYSTEM
Field of Invention The present invention relates to mounting and installation apparatus for use with solar photovoltaic an-ays and to a solar panel mounting system that incorporates such apparatus.
Backuound Since 2002, electrical power derived from photovoltaic cells has increased from less than 1 GWp/year to more than 100G\Vp/year as of the end of 2012. Moreover, photovoltaic (PV) systems are now used to generate power in over 100 countries around the world.
Continual research and development into improving the efficiency of PV systems has resulted in these devices becoming more economically viable as means for the production of electrical power from sunlight. For example, for crystalline silicon solar cell devices the cost of production of power was fallen from $77/Watt in 1977 to about $0.74/Watt in 2013. The cost of producing power from PV system is now less than that produced from nuclear sources and continues to fall.
Despite this rapid growth, PV electrical production still accounts for only about 0.5% of global electrical production capacity, and so remains an area where significant growth is yet to be realized. Part of the inherent cost of any PV system is that of installation.
Photovoltaic systems are generally provided as arrays of individual panels that are then linked together to produce the desired output. For example, a typical panel may produce on the order of 200-250W of power under full illumination. To create a system capable of practical output, a number of panels will be connected together as an array. For example, an array of 32 panels each capable of 225W can theoretically produce '7.2kW, which would generate enough power over the course of a year to offset the electrical energy needs of a typical household.
A drawback with this kind of arrangement is that it takes a significant amount of effort and time in order to build a mounting rack, install the individual panels onto the rack, and then make the electrical connections between each panel in the array and various other components such as inverters, ballasts and metering systems. As a result, for larger installations, there has been a trend towards manufacturers supplying pre-fabricated arrays on rack systems. These pre-assembled arrays can then be delivered to an installation site and more easily installed.
For example, seine companies now offer pre-fabricated racking systems that can be quickly installed on a building, typically on a rooftop. For example, U.S.
Patent Application Publication No. 2012/0036799 discloses a modular rack system designed to support a PV module, and which can be pre-fabricated into a rack array ready to receive PV panels. Using these system the rack is typically installed on a building roof, and then individual panels are installed and electrical connections made. This approach suffers from the problem that installation is still relatively labour intensive since a significant amount of assembly is required at the job site. Thus, what is needed in the industry is a PV array system that is substantially completely pre-fabricated, with the rack. PV
modules, and electrical components assembled in a factory setting. However, while in principle this might seem straightforward, in fact larger pre-fabricated arrays create other challenges.
For example, as the array and rack assembly become larger, there is a tendency of the rack to flex as it is moved or transported. Since PV panels comprise crystalline materials, flexing is a problem with PV panels fixed to racks, as the panels themselves are prone to damage if they are subjected to torsional stresses. Significantly, damage caused during assembly and transport may void the manufacturer's warranty coverage of the PV
panel.
One way in which to reduce flexing is to increase the rigidity of the members that comprise the rack portion of the system. However, increase the rigidity of rack members would normally be accomplished by increasing the size of the member. This would lead to significant increases in weight, which in turn leads to increased cost of production, transportation and difficulties in handling during installation.
As a result, there is a need in the industry for an improved design of PV
module racking systems that allows for the manufacture of essentially "plug and play" PV
arrays, and which protects the pre-fabricated array from damage to the PV modules during assembly, transport and installation.
List of Figures While the invention is claimed in the concluding portions hereof, preferred embodiments are provided in the accompanying detailed description which may be best understood in conjunction with the accompanying diagrams where like parts in each of the several diagrams are labeled with like numerals, and where:
Fig. 1 is a perspective view of an example of a PV module array installed on a.
rack support system according to one embodiment of the present invention.
Fig. 2 is a perspective view of an example of a PV module array where the PV
panels are attached to the rack hinges. The modules are in an upright, uninstalled configuration to show the panels before they are attached at the top edge.
Fig. 3 is a perspective view of the underside of an example of a PV module array showing support pads designed to support the weight of the array when installed on a structure such as a rooftop.
Fig. 4 is a perspective view of an example of a PV module array depicting PV
panels installed on a rack.
Fig. 5 is a side view of an. example of a PV module array showing the detail of the top edge mount in the transport configuration.
Fig. 6 is a perspective view of an example of a PV module array showing a hinge assembly in the transport configuration.
Fig. 7 is a perspective view of an example of a PV module array depicting PV
panels in the installed configuration and examples of electrical accessories that can be mounted on the rack underneath a PV panel.

Fig. 8 is a view of an example of a PV module array showing electrical conduit and wiring situated within the rack.
Fig. 9 is a view of an example of a PV module array showing a loading support that bears the load of the rack assembly during transport.
Fig. 10 is a view of an example of PV module arrays fully assembled and loaded on a transport, ready for delivery to a job-site.
Description of Invention The following discussion provides examples of embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A. B. and C. and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed. Those of skill in the art will recognize that the described embodiment are examples of possible configurations of the invention, and are not intended to be limiting, to the scope of the invention. Accordingly, the drawings and descriptions contained herein are to be regarded as illustrative of the invention as set forth in the accompanying claims.
These and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply. Similarly, in some cases alternative terms refer to the same item. For example PV
module and PV panel are generally understood to mean the same thing. A PV
array will refer to a plurality of PV modules connected together, generally, although not necessarily in a single rack.
Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints, and open-ended ranges should be interpreted to include commercially, practical values. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary.
In cases where dimensions or other measurements are provided in illustrations or the accompanying description, it is not intended that any such information is to be interpreted as limiting the scope of the invention.
As shown in Fig. 1, an example of the present inventive technology shows a series of PV
modules installed in a rack system. Racks are generally intended to be mounted on rooftops in order to make use of otherwise \\Fasted space. The rack system as described herein is also compatible with other types of mounting arrangements, such as post mounts, ground mounts, and mounts that are designed to steer the PV array such that it continually faces the sun during the course of the day.
Racks can also be fashioned to improve the efficiency of a solar array system.
As can be seen, in some cases the rack can be inclined at a gradient. The gradient provided by the rack can be selected based on the slope of the location where the array is to be installed, taking into consideration the average elevation of the sun above the horizon over the course of the year. For example, at higher latitudes for an installation on a flat roof, a steeper rack gradient would be desirable so that the PV array more directly faces the sun.
The inverse would be true where the array is to be installed on a sloped roof and/or at lower latitudes. Those of skill in the art will be readily able to determine an optimal rack gradient as described as an angle theta formed with reference to the top and bottom edges of the rack assembly.
Fig. 2 provides an example of a PV array and rack assembly vdiere the PV
panels are secured to a bottom edge of a rack, but are not yet attached to the top edge of the rack.
Conveniently, the PV module can be secured to the bottom edge (or hinge edge) of the rack with hinge assemblies. Each PV module can be secured to the rack by at least one hinge, and preferable two hinges, one generally at each side of the PV module.
'There is no specific number of hinges that are required, and it may be desirable where larger length PV panels are used to provide hinges near each end as well as hinges in the middle of the panel to better support the panel over its entire length.
Fig. 3 shows an example of a PV panel and rack assembly from underneath. In some case it may be advantageous to provide support pads secured to the underside of the rack.
These pads can be fashioned from any resilient material, for example, and without being limiting, polystyrene foam. The pads are designed to support the weight of the area on the structure \\here the array has been installed, for example on a rooftop.
The support pads further provide the advantage of spreading out the weight of the area so that the risk of overloading the roof structure at the points of contact between the array and the roof is essentially obviated. In some cases support pads can be provide at each comer of the anay and at locations between the corners. The spacing and number of pads will depend on the weight of the array and the particular structural characteristics. Pads may also be configured to be affixed onto mounting points, for example bolts, or other structures, and be able to be secured with fasteners to such structures. Such methods of securing solar arrays to buildings are well known in the art.
Fig. 4 depicts an exaniple of a PV array and rack system of the present invention, showing the PV panels in the installed configuration. As shown, the module can be secure to the rack by a top edge mount, vskiose structure and function will be described in greater detail below. As can also be seen the rack is designed to provide an enclosed space. The enclosure is able to keep rodents and other larger pests out from underneath the array. It also provides an enclosed area where other components can be placed and protected both from the elements and pests. For example, the bulk of the electrical wiring within the array that connects PV modules to each other can be placed within the enclosed space within the rack. Similarly, other electrical components such as inverters, ballast and wiring are able to fit within this enclosure. Conveniently, the rack sides can include venting slots to provide airflow through the rack and under the PV
panels in order to allow for heat to be dissipated by convection. In some applications, small electrical fan assemblies might also be placed under the PV panels within the enclosed rack space in order to actively move cooling air to dissipate heat generated while the system is in operation. Power for the fans could be derived from the output of the array itself.
Fig. 5 depicts an example of a top edge mount of the present invention in greater detail.
As shown, the mount assembly comprises a nut and bolt arrangement that secures the PV
panel to the rack assembly. In the transport configuration the nut and bolt are not tightened as is typical in prior art assemblies, but rather a space is left s that the PV panel is able to "float" above the top edge of the rack, and separation is provided between the panel and its rack.
In the transport configuration there is also provided a shock absorber spacer.
The spacer is designed to support the PV panel and maintain separation between the panel and the rack. In some cases the shock absorber can be formed from a resilient material such as a foain that allows some up and dowi movement of the PV panel along the length of the bolt while generally preventing the PV panel from corning into direct contact with the rack. A major advantage provided is that in the course of transportation of the solar array the PV modules are isolated from vibration and flexing of the rack as it is being moved.
This isolation system protects the PV panels from potential damage due to torsional strains and/or vibration as as might otherwise occur if the panels were securely attached to the rack. Vibration and torsion are common occurrences during handling of solar array assemblies, and the damage they cause is generally not covered by manufacturer warranties provided by solar panel makers.
In some cases, and as shown in Fig. 5, the shock absorber may be placed between a rack flange and the PV module in order to keep them separate during transport.
Conveniently, the shock absorber can be designed so that it is easily removable prior to final installation of the solar array. For example, the shock absorber may be attached to the rack flange with an temporary adhesive, for example the glue used on items like paper Post-It notes. The adhesive will be sufficiently secure tc) maintain the shock absorber in place during manufacture and transport of the array, but can be easily removed by hand when the array is in position and ready for the final steps in the installation process. In some cases it may be desirable to provide a shock absorber that slides onto the shaft of the bolt and supPorts the PV module, keeping it separate from the rack. In this case, the shock absorber might have a slit cut into one side to allow for easily placement onto the bolt shaft, with or without the need to a temporary adhesive.
As shown in Fig. 6, on the opposite edge of the PV panel there are provide hinges that secure the bottom edge of the pane to the bottom edge of the rack. As with the design of the top edge mount, the hinges are also designed with a nut and bolt arrangement that leaves a space between the PV module and the rack when in the transportation configuration. As with the top edge mount, a shock absorber can be placed within the space provided to maintain the separation between the PV module and rack, and to isolate the PV module from vibration and flexing during handling of a solar array.
Amin, like the top edge mount, once the rack is in place, the shock absorber can be removed and the nut and bolt assembly tightened to secure the PV module to the rack.
Alternatively, in some cases, it may be desirable to leave the shock absorber in place during installation and simply tighten the nut and bolt assemblies thereby compressing the shock absorber in place between the PV module and the rack assembly.
Leaving the shock absorber in place could provide an advantage where the solar array is installed in a high vibration location in order to maintain some isolation between the rack and the PV
modules. Similarly, leaving a spacer in place could provide additional electrical isolation between the panels and the rack on which they are mounted should that be desirable.
Regardless of the type and placement of the shock absorber, as part of the final installation procedure, the shock absorber can be removed (or not as the case may be), and the nut and bolt tightened in order to firmly secure the PV module to the rack. This step will typically be done once the array has been lifted into place and the rack secured to the rooftop or whatever structures it may be mounted on. Accordingly, during the lifting of the array into place, another point at which significant flexing of the rack can be experience, the PV modules are isolated from the vibration and flexion and are thus substantially protected from inadvertent damage during the installation process. Only once the array is safely in place will it be necessary to finally tighten the mounts. Until that time the panels will be isolated from the rack and thus protected from damage due to vibration and/or flexion.
Engineering studies conducted by the inventors using typical rack systems have shown that rack flexion of up to 2.5 mm are not uncommon during handling of a rack and solar array system. The spacing between the PV module and the rack provided by the bolt assembly and shock absorber can be easily designed to provide at least this much movement of the rack without significant flexion of the PV modules.
Fig. 7 depicts an example of the present invention showing how other electrical components can be conveniently placed within the enclosure formed by the, rack, taking advantage of otherwise wasted space. Placing components such as inverters and ballast provides the advantage of protecting these devices from the elements or common pests such as rodents. Placing these components within the rack space also precludes the need to mount these devices elsewhere. Further, as part of the overall advantage of providing a completely ready to "plug and play" solar array system, these components can be pre-connected to the PV modules within the array, again saving significant time during the installation of the array. Typically current systems require each of these electrical components to be installed once the array is in place, increasing the workload and time (as well as expense) required to put the array into commission.
Similarly, Fig. 8 depicts a rack assembly where the wiring is situated within conduit forming part of the rack stmcture. The conduit may be partially open or completely enclosed as desired. Enclosing the wiring protects it against damage due to the elements or pests. Conveniently, the pre-fabricated system can be produced such that all the wiring connections between individual PV modules, and other accessory components is completed at the factory. Unlike prior art systems where panels nmst be shipped separately from rack components to prevent damage during transport, the present system allows for an array to be essentially completely pre-fabricated such that an entire array is effectively operational with a single connection. This greatly simplifies the time and effort required to install and made such a system operational.
As shown in Fig. 9, .there can also be provided loading supports. These supports are desiped to allow for rack and panel assemblies to be stackable for transport.
These loading supports provide sufficient spacing so that individual arrays of PV
modules on racks can be stacked without the top of one assembly coming into contact with the bottom of an assembly stacked on top. In some cases, and as shown in Fig. 9, the loading support can include a resilient pad that provides vibration isolation between the transport vehicle and the rack assemblies, further protecting PV modules from the possibility of damage. The loading support can be designed to be removable, such that after off-loading of the assembly from the transport vehicle and prior to placement at the installation position, the support is removed from the assembly. As shown in Fig. 9, a simple pin and cotter pin arrangement permits the loading support to be easily removable from the rack assembly, while permitting the support to maintained securely in place until such time as it is to be removed.
The positioning and number of loading supports will vary depending on the size and weight of the rack and PV module array. At a minimum it will be preferable to have a loading support positioned at each comer of an an-ay assembly. For larger arrays it may be preferable to include additional support in order to better support the weight of the array while it is transported. As can be appreciated from the diagram the loading supports are designed to be stackable so that the entire load is supported generally vertically through the loading support member. As a result, there is no loading- on an individual rack assembly other than the load each assembly exerts on the loading support to which it is connected. This type of arrangement provides the ability to stack a number of an-ays without concern for overloading the rack assemblies towards the bottom of the stack. Put another way, the supports carry the load, not the racks.
Fig. 10 thus depicts an example of finished pre-fabricated arrays loaded on a truck for transport to an installation site. The stackable arrangement of the loading supports can be appreciated from the figure.
It will be recognized that the specific materials used in constructing the various components of the system described herein, are not considered to be limiting to the scope of the invention. Those of skill in the art will readily recognize and be able to select materials and components that will accomplish the objectives of the invention without requiring any inventive skill.

It should also be apparent to those skilled in the art that many more modifications besides those already described are possible without departing from the inventive concepts herein. The inventive subject matter, therefore, is not to be restricted except in the scope of the appended claims. Moreover, in interpreting bath the specification and the claims, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms "comprises" and "comprising" should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced.

Claims

What is claimed is: