Patent Description:
Photovoltaic modules (also referred to as "PV modules"), e.g., solar panels, are conventionally mounted in locations that are most prone to solar exposure. These locations include, for example, rooftops, open land, etc. Unfortunately, such locations are also exposed to snow, ice, wind, or other static and/or dynamic loads generated by the surrounding environment. A heavy snowfall or ice accumulation, or too strong a wind, can cause structural damage to the PV modules. Therefore, in an effort to ensure that commercially available PV modules can withstand the elements, manufacturers often test the designs in accordance with standardized testing procedures. In one known testing procedure, a number of sandbags are stacked onto the planar solar-exposed surface of a PV module for a specified period of time, for example. At the end of the specified period of time, the PV module is inspected for signs of physical damage.

<NPL> discloses an Array Structure Fatigue Tester, that is a machine designed to determine fatigue life of an array structure as an assembled unit, the machine simulates wind loading in both sustained and fatigue modes by substituting static air pressure for the velocity pressure generated by wind. The array structure to be tested is placed within a frame, a fan supplies the required pressure, simulating wind speed (the dominant loading mechanism) and corresponding environmental conditions. Sealed chambers above and below the array structures hold the simulated wind load, the machine is controlled by computer logic. Solenoid valves alternately permit air to inflate and exhaust the chambers to satisfy the correct load conditions.

<NPL>, discloses a cyclic pressure load test device to determine the ability of a photovoltaic module design to withstand mechanical fatigue by cyclically applying specific levels of positive and negative pressure loads that reflect the normal wind, snow, and ice loading. The test device comprises a test frame to permit mounting of the test item, two pressure panels, each including stiffeners, air duct, a plate with air distribution holes, rubber diaphragm (inflatable air bags), a vent valve and a pressure gauge to apply a uniform normal pressure to the front and back surfaces of the test modules, the device further comprises pressure control and timing equipment which provides regulated air to the pressure panels, provides control signals to alternately fill and vent the pressure panels, and includes a cycle counter.

One aspect of the present invention provides a device for testing the structural integrity of a planar surface as defined in claim <NUM> as appended hereto. The device includes a tub, a cavity, a membrane, and at least one opening. The tub has a bottom wall and at least one sidewall extending upward from a perimeter of the bottom wall. The cavity is defined between the bottom wall and the at least one sidewall of the tub. The membrane is disposed within the cavity at a location proximate to the bottom wall of the tub, and has a perimeter edge that is fixed to the tub. The opening is formed in the tub and adapted to receive a pressurized fluid to fill a portion of the cavity that is disposed between the membrane and the bottom wall to displace at least a portion of the membrane away from the bottom wall to apply a force to the planar surface during operation of the device.

A bed of media is disposed within the cavity on top of the membrane such that displacement of the membrane away from the bottom wall results in displacement of at least a portion of the bed of media away from the bottom wall and into engagement with the planar surface during operation of the device.

In one aspect, the bed of media can include a plurality of balls.

In one aspect, the bed of media can include three million plastic balls, each plastic ball having a diameter of approximately six millimeters.

In one aspect, the membrane can include an elastomeric material.

The device further includes at least one force sensor adapted to sense the force applied to the planar surface during operation of the device.

The device includes a u-shaped bracket attached to the tub and suspending the at least one force sensor opposite the planar surface from the membrane, e.g., above the planar surface.

In one aspect, the device can further include at least one pressurized fluid source connected to the at least one opening in the tub for delivering pressurized fluid to the cavity.

In one aspect, the device can further include an electronic control unit communicatively coupled to the at least one force sensor and the pressurized fluid source for controlling and monitoring operation of the device.

In one aspect, the electronic control unit can include a user interface for receiving user input and/or displaying output.

In one aspect, the device can further include at least one adjustment panel horizontally disposed through the at least one sidewall of the tub and adapted to be adjusted to extend between the at least one sidewall and approximately a perimeter of the planar surface during operation of the device. In another aspect, the present invention provides a method for testing the structural integrity of a planar surface as defined in claim <NUM> as appended hereto. The method includes positioning a planar surface above a membrane disposed within a cavity of a tub, wherein the cavity is defined between a bottom wall and at least one sidewall of the tub. The method further includes positioning a planar surface onto a bed of media disposed within the cavity and supported by the membrane. The method further includes introducing a pressurized fluid into a portion of the cavity that is disposed between the bottom wall of the tub and the membrane. The method further includes displacing at least a portion of the membrane and the bed of media away from the bottom wall of the tub and into engagement with the planar surface with the pressurized fluid. The method further includes applying a force to the planar surface, the force being transferred through the membrane.

In some aspects, applying a force to the planar surface can include applying a force of a predetermined magnitude for a predetermined duration.

In some aspects, applying a force to the planar surface can include applying a force of uniform magnitude across the planar surface.

In some aspects, displacing at least a portion of the bed of media can include displacing a plurality of plastic balls into engagement with the planar surface.

In some aspects, introducing a pressurized fluid into a portion of the cavity can include delivering a pressurized gas into a portion of the cavity.

The method further comprises detecting a magnitude of the force being applied to the planar surface with at least one force sensor.

In some aspects, the method can further comprise controlling a duration of the force being applied to the planar surface.

In some aspects, the method can further comprise inputting one or more of the following parameters into a user interface prior to introducing the pressurized fluid into the cavity: (a) a magnitude of the force to be applied to the planar surface; (b) a duration for which the force is to be applied to the planar surface; (c) a total number of cycles through which the force is to be applied the planar surface; and (d) a duration of any pause between cycles through which the force is to be applied to the planar surface.

Although the following text sets forth a detailed description of one or more embodiments of the invention, it should be understood that the legal scope of the invention is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment of the invention since describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, which would still fall within the scope of the claims defining the invention.

It should also be understood that, unless a term is expressly defined in this patent using the sentence "As used herein, the term '_____' is hereby defined to mean. " or a similar sentence, there is no intent to limit the meaning of that term, either expressly or by implication, beyond its plain or ordinary meaning, and such term should not be interpreted to be limited in scope based on any statement made in any section of this patent (other than the language of the claims).

In general, the device and method described herein are for generating a substantially uniform load, e.g., force, in a direction transverse to a two-dimensional plane for testing the structural integrity of a planar surface or a planar article such as a photovoltaic module (hereinafter "PV module"). Such tests are aimed at determining the ability of a PV module to withstand static and/or dynamic loads generated from wind, ice, snow, etc., and can be performed in accordance with various standardized testing protocols such as UL <NUM> section <NUM>, IEC <NUM> section <NUM>, and IEC <NUM> section <NUM>. While the device and method disclosed herein are generally designed for testing PV modules, they can also be used to test the structural integrity of other devices, or for any other foreseeable testing operation, manufacturing operation, or other function where a generally uniform load across a two-dimensional plane may be desired.

<FIG> include a pair of schematic cross-sectional representations of a device <NUM> constructed in accordance with the present disclosure. In <FIG>, the device <NUM> is shown occupying a passive state, e.g., non-operating state. In <FIG>, the device <NUM> is shown occupying an active state, e.g., operating state. As illustrated in <FIG>, one example of the device <NUM> can generally include a steel tub <NUM>, a membrane <NUM>, a bed of media <NUM>, at least one overhead U-shaped bracket <NUM>, and a plurality of force sensors <NUM>. Additionally, as shown, one embodiment of the device <NUM> can include a plurality of adjustable panels <NUM> (only two panels 22a, 22c, of which are visible in <FIG>), at least one fluid opening <NUM>, and a puller bar <NUM>, each of which will be described in further detail below.

The tub <NUM> can generally resemble a box with an open top, for example, including a bottom wall <NUM>, at least one sidewall <NUM> extending upward around a perimeter of the bottom wall <NUM>, and a cavity <NUM> defined between the bottom wall <NUM> and the at least one sidewall <NUM>. In the disclosed embodiment, the at least one sidewall <NUM> of the tub <NUM> includes four sidewalls 26a-26d, as shown more particularly in <FIG>, such that the tub <NUM> has a generally square or rectangular shape when viewed from the top or bottom. In other embodiments, the tub <NUM> can have generally any shape when viewed from the top and/or bottom.

The membrane <NUM> includes a sheet of material disposed in the cavity <NUM> of the tub <NUM> proximate to the bottom wall <NUM>, and mounted to the tub <NUM> to provide a generally fluid tight seal therebetween. In some embodiments, the membrane <NUM> can be mounted adjacent to its perimeter edge to the bottom wall <NUM> of the tub <NUM> with L-brackets or some other means, for example. In some other embodiments, the membrane <NUM> can be mounted adjacent to its perimeter edge to each of the sidewalls 26a-26d of the tub <NUM>. So configured, the membrane <NUM> can be mounted at a height in the tub <NUM> so as not to contact the bottom wall <NUM> of the tub <NUM> when the device occupies the passive state, as shown in <FIG>, for example. However, a certain amount of contact resulting from the membrane <NUM> sagging under the weight of the bed of media <NUM> can be acceptable. In one embodiment, the membrane <NUM> can be constructed of a substantially inelastic material, an elastic material, a flexible material, an elastomeric material, or generally any other type of material suitable for the intended purpose.

The bed of media <NUM> can include a plurality of balls <NUM> disposed in the tub <NUM> on top of the membrane <NUM>. In one example, the plurality of balls <NUM> can include <NUM> million spherical plastic balls, each ball being approximately <NUM> millimeters in diameter. This is merely an example and other embodiments can include generally number and/or size of balls <NUM> suitable for the intended purpose. In other embodiments, the bed of media <NUM> can include generally any type of media capable of serving the intended purpose. For example, the bed of media <NUM> can include a plurality of objects having generally any shape, the objects being the same or different in shape, size, density, etc., or the bed of media <NUM> can include a fluid such as a liquid or a gas, or even a gel or other type of deformable mass. In one alternative embodiment, the device <NUM> could further include a second membrane (not shown) disposed opposite the bed of media <NUM> from the membrane <NUM>, e.g., on top of the bed of media <NUM>, such that the bed of media <NUM> is sandwiched between two membranes. Two membranes could be especially useful in an embodiment where the bed of media <NUM> includes a bed of fluid, for example, for retaining the fluid in the tub <NUM> both during operation and when the device <NUM> is non-operational.

The at least one overhead U-shaped bracket <NUM>, as illustrated, carries the plurality of force sensors <NUM> such that the force sensors <NUM> are suspended above the bed of media <NUM> and the membrane <NUM> at a location opposite the bed of media <NUM> from the membrane <NUM>.

Still referring to <FIG>, a planar article <NUM>, which constitutes a PV module <NUM> in this example, is shown positioned in the device <NUM>. In the disclosed embodiment, the PV module <NUM> includes a photovoltaic panel <NUM> (hereinafter "PV panel") mounted to a pair of roof brackets <NUM>, only one of which is visible in <FIG>. Each of the roof brackets <NUM> includes a generally straight member mounted to the backside of the PV panel <NUM> parallel to the other roof bracket <NUM>.

As shown, the PV module <NUM> is disposed in the tub <NUM> on top of the bed of media <NUM>, and beneath the force sensors <NUM>. In <FIG>, the roof brackets <NUM> face upward and are aligned with the force sensors <NUM>, and a front planar surface 42a of the PV panel <NUM> faces downward and is in contact with the bed of media <NUM>. So configured, the PV module <NUM> depicted in <FIG> can be described as occupying an "upside-down" orientation.

Depending on the specific testing process being conducted, however, the PV module <NUM> could be turned over relative to the "upside-down" orientation to occupy a "right-side up" orientation. When disposed "right-side up," the front planar surface 42a of the PV panel <NUM> faces upward toward the force sensors <NUM> and the roof brackets <NUM> face downward and are in contact with the bed of media <NUM>. So configured, the roof brackets <NUM> sink into, e.g., penetrate, the top surface of the bed of media <NUM> such that the bed of media <NUM> is in direct uniform contact with a rear planar surface 42b of the PV panel <NUM>. In this "right-side up" orientation, the roof brackets <NUM> would still be aligned with the force sensors <NUM>, but the force sensors <NUM> would instead be engaged by the PV panel <NUM>.

In embodiments where the device <NUM> includes a second membrane on top of the bed of media <NUM> and wherein the PV module <NUM> is loaded "upside-down" (as shown in <FIG>), the front planar surface 42a of the PV panel <NUM> would be supported directly on the second membrane. In embodiments with a second membrane and where the PV module <NUM> is loaded "right-side up," the roof brackets <NUM> would necessarily deform the second membrane to enable the brackets <NUM> to sink into the bed of media <NUM>. Such deformation of the membrane in the vicinity of the roof brackets <NUM> would preferably not limit the extent to which the bed of media <NUM> is capable of contacting the rear planar surface 42b PV panel <NUM> in a uniform manner.

Moreover, as mentioned above, the device <NUM> of the disclosed embodiment can be equipped with the plurality of adjustable panels <NUM>. The plurality of panels <NUM> includes four adjustable panels 22a-22d, one slidably disposed through each of the four sidewalls 26a-26d. As shown in <FIG>, the panels <NUM> are positioned between the membrane <NUM> and the bed of media <NUM> in the vertical direction and between a perimeter of the PV module <NUM> and the sidewalls 26a-26d of the tub <NUM> in the horizontal direction. This configuration can limit the expansion and/or deflection of the membrane <NUM> during operation to the region located within the perimeter boundaries of the PV module <NUM>.

For example, during operation of the device <NUM>, a pneumatic line (not shown in <FIG>) is connected to the fluid opening <NUM> disposed in the bottom wall <NUM> of the tub <NUM> and a pressurized gas is introduced into a portion 28a of the cavity <NUM> that is disposed between the membrane <NUM> and the bottom wall <NUM>. In some embodiments, gas is introduced at a pressure in the range of approximately <NUM> mbar to approximately <NUM> mbar. While the present embodiment of the tub <NUM> includes only a single opening <NUM>, alternative embodiments can have a plurality of openings <NUM> spaced about the bottom wall <NUM>, each being connected to its own pneumatic line. Such a configuration can increase the uniformity of the introduction of gas to the cavity. In any event, the pressurized gas causes at least the portion of the membrane <NUM> that is located between the adjustable panels 22a-22d to displace upwardly away from the bottom wall <NUM>, as shown <FIG>.

In some embodiments, displacement of the membrane <NUM> can result in the membrane <NUM> resiliently deforming, for example, by stretching similar to a balloon under the pressure of the gas delivered to the portion 28a of the cavity <NUM> of the tub <NUM>. Regardless, displacement of the membrane <NUM> upward, in turn, causes the membrane <NUM> to displace at least a portion of the bed of media <NUM> upwardly away from the bottom wall <NUM> and into forceful engagement with 42a the PV panel <NUM> of the PV module <NUM> and, in the depicted embodiment, the front planar surface 42a of the PV panel <NUM>. This force, in turn, displaces the PV module <NUM> upwardly away from the bottom wall <NUM> and into engagement with the force sensors <NUM> carried by the overhead U-shaped brackets <NUM>. The force sensors <NUM> are adapted to detect the magnitude of the force being applied to the PV module <NUM>. As mentioned, the bed of media <NUM> applies a generally uniform force across the PV panel <NUM> of the PV module <NUM>, and in the depicted embodiment, across the front planar surface 42a of the PV panel <NUM>. This uniform application of force is achieved because the bed of media <NUM> acts similar to a fluid in that in the disclosed embodiment, the three million plastic balls <NUM> move relative to each other to uniformly distribute the load applied by the membrane <NUM> through the balls <NUM> and onto the PV panel <NUM>. Actual fluids and other types of media can operate similarly.

<FIG> depicts a specific construction of some of the components of one embodiment of the load generating device <NUM> of the present disclosure. For example, as shown in <FIG>, in one embodiment, the steel tub <NUM> includes a frame <NUM> constructed of steel tubes and including legs 44a supporting the device on a floor, for example. The bottom wall <NUM> and the sidewalls 26a-26d are each constructed of a sheet metal material and can be welded or otherwise fixed to the frame <NUM>. The membrane <NUM> is fixed into the tub <NUM>, as shown generally in <FIG>, with a plurality of angle fixtures <NUM>, which are shown in <FIG>. Each angle fixture <NUM> can include an elongate metal member having an L-shaped cross-section, and which can be secured to the frame <NUM> of the tub <NUM> or directly to the bottom wall <NUM> or sidewalls 26a-26d of the tub <NUM> with screws, welding, rivets, or any other means, for example.

As shown in <FIG>, each of the overhead U-shaped brackets <NUM> can be mounted with screws <NUM> to the topmost steel tube <NUM> of the frame <NUM>. Preferably, the topmost tube <NUM> can include a plurality of different sets of holes for receiving the screws <NUM>, such that the position of the overhead U-shaped brackets <NUM> can be adjusted to accommodate PV modules <NUM> having roof brackets <NUM> of different spacing.

As discussed above, the device <NUM> can include adjustable panels <NUM> for focusing the deflection of the membrane <NUM> to the area disposed between the perimeter boundaries of the PV module <NUM>. The adjustable panels <NUM> can be adjusted by sliding horizontally through elongated openings (not shown) in the sidewalls 26a-26d of the tub <NUM>. As depicted, the adjustable panels <NUM> include guide pins <NUM> disposed on opposing sides that are adapted to be slidably disposed in corresponding guide brackets <NUM> mounted on the outside of the tub <NUM>, only some of which can be seen in <FIG>. This sliding arrangement enables the position of the panels <NUM> to be adjusted in and out of the tub <NUM>, thereby being adjustable to accommodate PV modules <NUM> of different dimensions. Preferably, a set screw (not shown) can be utilized to fix the position of each of the adjustment panels <NUM> prior to operating the device <NUM>. In one embodiment, one set screw can be threaded through each of the guide brackets <NUM> to frictionally engage the corresponding guide pin <NUM>, thereby locking the guide pins <NUM> and panels <NUM> in position.

Finally, as mentioned above with reference to <FIG>, the device <NUM> of the presently disclosed embodiment can include the puller bar <NUM>. As shown in <FIG>, the puller bar <NUM> constitutes an elongated bar adapted to be slidably mounted in the tub <NUM> at a height that corresponds to a top surface of the bed of media <NUM>, as shown in <FIG>. So configured, after a loading operation is completed and the PV module <NUM> is removed from the tub <NUM>, a technician can slide the puller bar <NUM> across the tub <NUM> to level the bed of media <NUM> in preparation for the next loading operation. Moreover, the device <NUM> can further be equipped with a vibrating mechanism such as a shaker table (not shown), for example, which can be activated when the PV module <NUM> is loaded right-side up, for example (i.e., when the roof brackets <NUM> are disposed in contact with the bed of media <NUM>). With this orientation of the PV module <NUM>, the vibrating mechanism can be activated to vibrate the bed of media <NUM> and/or the PV module <NUM> to obtain good displacement of the plastic balls <NUM> around the roof brackets <NUM> such that the balls <NUM> evenly distribute and uniformly contact the rear planar surface of the PV panel <NUM>.

As mentioned above, one application for the device <NUM> of the present disclosure is for testing the structural integrity of PV modules <NUM>. To facilitate such tests, the device <NUM> can be incorporated into a system <NUM>, as depicted in <FIG>, for example. The system <NUM> of <FIG> includes the device <NUM>, an electronic control unit <NUM>, and a pressure control unit <NUM>.

In the disclosed embodiment, the electronic control unit <NUM> can include a personal computer (hereinafter "PC") <NUM>, an A/D unit <NUM>, and a relay unit <NUM>. The PC <NUM> can include a user interface <NUM> including, for example, an input device <NUM> such as a keyboard or touchscreen for enabling a user to input data into the PC <NUM>, and an output device <NUM> such as a monitor, printer, speaker, or other device for conveying information to the user. Additionally, although not illustrated in <FIG>, it should be appreciated that the PC <NUM> can include a processor, a RAM memory, a ROM memory, and/or any other component typically associated with a conventional computing device. The pressure control unit <NUM> includes at least one pressurized gas source <NUM> and at least one pressure control valve <NUM>, for example. The A/D unit <NUM> includes a conventional analog/digital converter. The relay unit <NUM> acts as a conventional switch for controlling the flow of power to the load generating device <NUM> and the pressure control unit <NUM> in response to appropriate direction received from the PC <NUM>.

As illustrated in <FIG>, the PC <NUM> is communicatively coupled to the A/D unit <NUM> and the relay unit <NUM> via communication lines <NUM>, <NUM>, respectively. Moreover, as illustrated, the A/D unit <NUM> is communicatively coupled to the pressure control unit <NUM> via a communication line <NUM>, and to the load generating device <NUM> via a communication line <NUM>. In an embodiment, wherein the load generating device <NUM> includes a vibrating mechanism for evenly distributing the plastic balls <NUM> of the bed of media <NUM> around the roof brackets <NUM> of the PV module <NUM>, as discussed above,, the relay unit <NUM> can be communicatively coupled to the load generating device <NUM> via a power line <NUM>. Additionally, the relay unit <NUM> is communicatively coupled to the pressure control unit <NUM> via a power line <NUM>. Finally, the pressure control unit <NUM> includes a pneumatic line <NUM> connected to the load generating device <NUM> and, more particularly, to the fluid opening <NUM> in the bottom wall <NUM> of the tub <NUM> of the device <NUM>, as discussed above with reference to <FIG>.

With reference now to the flowchart depicted in <FIG>, a method of testing a PV module <NUM> will be described using the load generating device <NUM> and system <NUM> of <FIG>. First, at block <NUM>, a user can enter data related to the forthcoming testing procedure into the PC <NUM> via the user interface <NUM>. The data may include, for example, information indicative of the PV module <NUM> to be tested, information indicative of the test procedure to be performed, information indicative of the type and/or number of reports to be generated at the completion of the testing procedure, and/or any other foreseeable data.

Information indicative of the PV module <NUM> can include the dimensions of the PV module <NUM>, the weight of the PV module <NUM>, the material or materials of which the PV module <NUM> is constructed, the manufacturer of the PV module <NUM>, the model number and/or serial number of the PV module <NUM>, etc. Information indicative of the test procedure can include, for example, a magnitude of a target force to be applied to the the PV module <NUM>, a duration for which the target force is to be applied to the PV module <NUM>, a total number of cycles through which the target force is to be applied to the PV module <NUM>, a duration of any pause between cycles through which the target force is to be applied to the PV module <NUM>, a pressure at which gas is delivered to the device <NUM> during operation, a velocity at which gas is delivered to the device <NUM> during operation, etc..

At block <NUM> of <FIG>, the PV module <NUM> can be positioned upside-down into the tub <NUM> of the device <NUM> such that its front planar surface 42a is disposed in contact with the bed of media <NUM>, as described above with reference to <FIG>. Alternatively, block <NUM> can include positioning the PV module <NUM> into the tub <NUM> right-side up such that the roof brackets <NUM> and the rear planar surface 42b of the PV module <NUM> are disposed in contact with the bed of media <NUM>. When the PV module <NUM> is positioned right-side up, block <NUM> can further include activating a vibrating mechanism, as discussed above, to evenly distribute the bed of media <NUM> around the roof brackets <NUM> and into contact with the rear planar surface of the PV panel <NUM>. Specifically, block <NUM> can include the PC <NUM> sending a signal to the relay unit <NUM> over communication line <NUM> instructing the relay unit <NUM> to activate the vibrating mechanism by energizing power line <NUM> for a specified duration. Additionally, block <NUM> can include any desired adjustment of the position of the adjustable panels 22a-22d discussed above.

With the PV module <NUM> loaded into the tub <NUM>, the PC <NUM> can initiate the testing procedure at block <NUM>. At block <NUM>, the PC <NUM> sends a digital signal to the A/D unit <NUM> over communication line <NUM> indicative of the initial force to be applied to the PV module <NUM>, and sends a separate digital signal to the relay unit <NUM> over communication line <NUM> instructing the relay unit <NUM> to switch open the supply of power to the pressure control unit <NUM>. At block <NUM>, the A/D unit <NUM> converts the signal received from the PC <NUM> to an analog signal and transmits the analog signal to the pressure control unit <NUM> over communication line <NUM>. At block <NUM>, the energized pressure control unit <NUM> opens the control valve <NUM> to an extent that is based on the analog signal received from the A/D unit <NUM>.

With the control valve <NUM> opened, pressurized gas flows from the pressurized gas source <NUM>, through the pneumatic line <NUM>, and into the portion 28a of the cavity <NUM> of the tub <NUM>, as indicated at block <NUM> and described above with reference to <FIG>. As indicated at block <NUM>, the pressurized gas causes the membrane <NUM> to displace upwardly away from the bottom wall <NUM> of the tub <NUM>. The displacement of the membrane <NUM>, in turn, causes at least a portion of the bed of media <NUM> to displace upwardly away from the bottom wall <NUM> of the tub <NUM>, as indicated at block <NUM>, and apply a force to the PV module <NUM>, as indicated at block <NUM>. The force applied to the PV module <NUM> is uniform across its two-dimensional surface and it displaces the PV module <NUM> into engagement with the force sensors <NUM> carried by the upper U-shaped brackets <NUM>. The brackets <NUM> detect the magnitude of the force being applied to the PV module <NUM>, as indicated at block <NUM>. At block <NUM>, each of the force sensors <NUM> transmit the detected forces to the A/D unit <NUM>, or alternatively, the A/D unit <NUM> extracts the detected forces from each of the force sensors <NUM>. At block <NUM>, the A/D unit <NUM> converts the detected forces to one or more digital signals and transmits the signal(s) to the PC <NUM>.

At block <NUM>, the PC <NUM> determines whether the detected forces match the target force for the particular test procedure being conducted. If the forces do not match the target force, the PC <NUM> sends an adjusted digital signal to the A/D unit <NUM> at block <NUM>, which then sends an adjusted analog signal to the pressure control unit <NUM> to adjust the opening of the control valve <NUM>, which in turn, adjusts the amount of pressure being supplied to the tub <NUM> via pneumatic line <NUM>. The process then returns to block <NUM>.

In contrast, if the forces detected by the force sensors <NUM> match the target force, the PC <NUM> waits for a specified duration, as indicated at block <NUM>. The specified duration corresponds to a duration dictated by the particular testing procedure being conducted, for example, or by the data input to the PC <NUM> at block <NUM> discussed above. At the end of the specified duration, the PC <NUM> sends a digital signal to the A/D unit <NUM> indicative of a close command, in response to which, the A/D unit <NUM> sends an analog signal to the pressure control unit <NUM> to close the pressure control valve <NUM> and stop supplying pressurized gas to the tub <NUM>, as indicated at block <NUM>. Simultaneously, any pressure built up in the tub <NUM> can be automatically vented through an exhaust valve (not shown) connected to the tub <NUM>, for example, or through an exhaust valve associated with the pressure control valve <NUM> itself. At this point, the membrane <NUM> and bed of media <NUM> return to their passive state, shown in <FIG>.

At block <NUM>, it is determined if additional loading cycles are dictated by the particular testing procedure being conducted. If no additional loading cycles are desired, the testing procedure is complete, as indicated at block <NUM>, and the PV module <NUM> can be removed from the device <NUM>. Prior to loading a subsequent PV module <NUM> for testing, the bed of media <NUM> can be leveled, as indicated at block <NUM>, through operation of the puller bar <NUM> discussed above. Alternatively, in embodiments wherein the load generating device <NUM> includes a vibrating mechanism, the vibrating mechanism could also be used to level the bed of media <NUM> between testing operations. In such a process, the PC <NUM> could send a signal to the relay unit <NUM> over communication line <NUM> instructing the relay unit <NUM> to activate the vibrating mechanism by energizing power line <NUM> for a specified duration to level the bed of media <NUM>.

Alternatively, if additional loading cycles are desired or required to complete the testing procedure, the PC <NUM> waits for a designated pause duration, as indicated at block <NUM>, prior to returning to block <NUM> to repeat the previously described process. Depending on the particular test being conducted, subsequent loading cycles may apply a force to the PV module <NUM> that is the same as or different from the magnitude previously applied. Moreover, subsequent loading cycles may apply a force to the PV module <NUM> for a duration that is the same as or different from the previous duration. The magnitude and duration of the force applied to the PV module <NUM> during each cycle of any testing procedure can be dictated and controlled by the electronic control unit <NUM> such that any give testing process is accurate and repeatable. Moreover, as mentioned, at the conclusion of any given testing process, the electronic control unit <NUM> of the present disclosure is advantageously capable of generating any number and/or style of reports related to the testing process including data, graphs, and analysis related to the magnitude and duration of the forces applied to the PV modules <NUM>. Such reports could be generated on the display device <NUM> of the user interface <NUM> of the PC <NUM>, saved to a memory, or printed in hard copy, for example.

While the load generating device <NUM> of the present invention includes a bed of media <NUM> disposed on top of the membrane <NUM>, at least one alternative embodiment of the device <NUM>, which is not part of the present invention, can be constructed without the bed of media <NUM>. For example, as illustrated in <FIG>, one alternative load generating device <NUM> can include all of the features of the device <NUM> described above with reference to <FIG>, but for the bed of media <NUM>. With this embodiment of the device <NUM>, the introduction of pressurized gas into the portion 28a of the cavity <NUM> disposed below the membrane <NUM> causes the membrane <NUM> to displace or deflect upward and into direct engagement with a planar surface of a planar article being tested, which in <FIG> constitutes a front planar surface 42a of a PV panel <NUM> of a PV module <NUM>. The displacement of the membrane <NUM> forcefully engages the PV module <NUM> and forces the PV module <NUM> into engagement with the force sensors <NUM> in a manner generally similar to that described above with reference to <FIG>. The device depicted in <FIG> could easily by used in the system described with reference to <FIG>. Moreover, the method described above with reference to <FIG> could easily be adapted to be performed using the device <NUM> depicted in <FIG>. The difference is that loading the PV module <NUM> into the device <NUM> of <FIG> simply includes positioning the PV module <NUM> directly on the membrane <NUM>, and any force applied to the membrane <NUM> by the pressurized gas introduced through the opening <NUM> in the tub <NUM>, would be transferred directly to the PV module <NUM> without distribution through the bed of media <NUM>.

In view of the foregoing, it should be appreciated that the present disclosure advantageously provides among other advantages (a) a device capable of generating a uniform force across a two-dimensional planar surface; (b) a device that has the ability to generate detailed test results such as the magnitude of the force applied to the PV module, the duration of the test, the force carried by the roof brackets at the specific locations of the force sensors, etc.; and (c) the device and method enable a very quick, efficient, automated, and repeatable test procedure.

Claim 1:
A device (<NUM>) for testing the structural integrity of a planar surface (<NUM>), the device (<NUM>) comprising:
a tub (<NUM>) having a bottom wall (<NUM>) and at least one sidewall (<NUM>) extending upward from a perimeter of the bottom wall (<NUM>);
a cavity (<NUM>) defined between the bottom wall (<NUM>) and the at least one sidewall (<NUM>) of the tub (<NUM>);
a membrane (<NUM>) disposed within the cavity (<NUM>) at a location proximate to the bottom wall (<NUM>) of the tub (<NUM>), the membrane (<NUM>) having a perimeter edge that is fixed to the tub (<NUM>), such that the planar surface (<NUM>) can be disposed above the membrane (<NUM>);
an opening (<NUM>) formed in the tub (<NUM>), the opening (<NUM>) adapted to receive a pressurized fluid to fill a portion of the cavity (<NUM>) that is disposed between the membrane (<NUM>) and the bottom wall (<NUM>) to displace at least a portion of the membrane (<NUM>) away from the bottom wall (<NUM>) to apply a force to the planar surface (<NUM>) during operation of the device (<NUM>);
a bed of media (<NUM>) disposed within the cavity (<NUM>) on top of the membrane (<NUM>) such that displacement of the membrane (<NUM>) away from the bottom wall (<NUM>) results in displacement of at least a portion of the bed of media (<NUM>) away from the bottom wall (<NUM>) and into engagement with the planar surface (<NUM>) during operation of the device (<NUM>); and
at least one force sensor (<NUM>) adapted to sense the force applied to the planar surface during operation of the device
the device (<NUM>) further comprising a u-shaped bracket (<NUM>) attached to the tub (<NUM>) and suspending the at least one force sensor (<NUM>) opposite the planar surface (<NUM>) from the membrane (<NUM>),
wherein during the operation of the device, the planar surface is displaced upwardly away from the bottom wall (<NUM>) and into engagement with the at least one force sensor (<NUM>).