The 2011 National Electric Code (NEC) 690.11 includes a requirement to both detect and suppress an electrical arc in connection with new photovoltaic installations. Frequently, conventional rack mounted solar panels are strung together in such a way that breaking the circuit is sufficient to extinguish an arc. In these systems, it is uncommon for voltage potentials greater than 100V to be present in the same panel. Accordingly, the photovoltaic industry has focused on detecting and suppressing series arcs. However, as alternative photovoltaic designs and installations are developed, including designs where the photovoltaic article also serves as building cladding (sometimes referred to as building integrated photovoltaics or BIPV), certain system and array designs may lead to relatively high voltage potentially in nearby electrical bus lines. In certain arrays constructed of multiple BIPV articles, however, the home-run bus runs parallel to the operating bus, and some shingles may have up to 600V potential between the two busses. In such a case, both series and parallel arcing are theoretically possible.
In one aspect, the technology relates to a solar array kit useful in forming a solar array system, the kit including: a continuity signal generator having connectors for connecting a solar array circuit, wherein the continuity signal generator is adapted to deliver a continuity signal to the solar array circuit; and a detection circuit having connectors for connecting to the solar array circuit, the detection circuit including: a continuity signal sensor; at least one switch for selectively opening and closing the solar array circuit; and a switch controller operatively connected to the switch and the continuity signal sensor, wherein the switch controller includes a connector for connecting to a power source, and wherein the switch controller is adapted to actuate the switch upon receipt of a control signal from the detection circuit. In one embodiment, the solar array kit includes at least one solar cell having connectors for connecting to the solar array circuit and the detection circuit. In another embodiment, the control signal includes the continuity signal. In yet another embodiment, the detection circuit further includes an amplifier for amplifying a solar array signal and a filter for filtering the solar array signal, and wherein the solar array signal includes the continuity signal. In still another embodiment, the switch controller connector is adapted to connect to a power source discrete from the solar array circuit.
In another embodiment of the above aspect, the switch controller connector is adapted to connect to the solar array circuit, wherein the solar array circuit is adapted to deliver power to the switch. In yet another embodiment, the power source discrete from the solar array circuit has at least one of: discrete solar power generation cell including connectors for connecting to the switch controller connector; and a magnetic flux generator including a first inductor and a second inductor, the first inductor and second inductor arranged so as to generate a magnetic flux between the first inductor and the second inductor, and wherein the second inductor has connectors for connecting to the switch controller connector. In still another embodiment, the at least one switch includes at least one of a metal-oxide-semiconductor field-effect transistor, a solid-state switch, and a mechanical switch.
In another embodiment of the above aspect, the continuity signal sensor includes at least one of a transformer, an antenna, and a hard-wire connection.
In another aspect, the technology relates to a method for maintaining a solar array circuit, the method including: detecting a solar array signal on a solar array circuit; and sending a control signal to a solar array circuit switch, based on the presence of a continuity signal in the solar array signal. In one embodiment, the method further includes: generating the continuity signal; and routing the continuity signal onto the solar array circuit. In another embodiment, the method further includes closing the solar array circuit upon receipt of the control signal. In yet another embodiment, the control signal includes the continuity signal. In still another embodiment, the solar array signal includes a direct current component, and wherein the continuity signal includes an alternating current component.
In another embodiment of the above aspect, the solar array signal is generated by at least one solar cell. In yet another embodiment, the method further includes at least one of filtering the detected solar array signal, amplifying the detected solar array signal, and rectifying the detected solar array signal. In still another embodiment, the method further includes delivering power to the switch from a power source discrete from the solar array circuit.
In another embodiment of the above aspect, the power source includes at least one of a solar cell discrete from the solar array circuit, a magnetic flux generator, and a building power service. In yet another embodiment, the method includes delivering power to the switch from the solar array circuit. In still another embodiment, the solar array signal is detected via at least one of an antenna, a transformer, and a hard-wire connection.
There are shown in the drawings, embodiments which are presently preferred, it being understood, however, that the technology is not limited to the precise arrangements and instrumentalities shown.
The technology described herein has particular application in the residential solar market. Solar power generation modules may be building integrated solar modules, also referred to as a building integrated photovoltaics (BIPV), which may be used to replace conventional building materials in parts of a building envelope such as the roof, skylights, or facades. The module may be a thin film solar cell integrated to a flexible polymer roofing membrane, a module configured to resemble one or more roofing shingles (for example, the POWERHOUSE brand of BIPV shingles manufactured by the Dow Chemical Company), or semitransparent modules used to replace architectural elements commonly made with glass or similar materials, such as windows and skylights. Alternatively, the solar module may be a rigid solar module mounted to an architectural element such as a roof or installed within a large field array. In short, the technology is not limited to building integrated photovoltaic or arrays having discrete sensor modules and generator modules.
The systems for detecting discontinuities and suppressing current in a solar array system may be used with solar array systems utilizing BIPV articles, as well as in conventional rack mounted solar panels used in small arrays or large-scale field arrays. The unique advantages of the described systems make them particularly useful in BIPV array. Accordingly, that application is described herein.
Broadly described, the discontinuities detected with the technologies described herein may be indicative of two types of arc events. Series arcs occur when an open is established in one of the bus paths and the open is exposed to enough voltage to arc across the open. The series arc would occur somewhere on the “+” line bus or the “−” line bus. A parallel arc occurs when the bus voltage is sufficient to bridge the gap from the “+” bus to the “−” bus and therefore appears somewhere between the “+” bus and the “−” bus. Both types of arcs will degrade the circuit quality through the shingle array sufficiently to prevent communication of a control signal over the same circuit.
The systems and methods described herein detect discontinuities within the solar array circuit, such as those discontinuities caused by arc events or other anomalies within the solar array. More accurately, a composite signal, or solar array signal, passing through the solar array circuit is continuously monitored for anomalies that may indicate a potentially undesired condition within the circuit, i.e., an arc. This composite signal, or solar array signal, has two components. A primary component of the composite signal is from the power generated by the solar cells and is characterized by a direct current, as is typical for solar installations. A second component is a continuity signal having an alternating current that is generated remotely from the solar array circuit. In some embodiments the continuity signal may be a square wave, individual pulses, or any other signal known in the art. This continuity signal is overlaid onto the direct current power signal such that both components may be detected during operation of the solar array circuit. Anomalies detected in this composite signal, for example, an absence of the continuity signal in the composite signal, are indicative of an event such as an arc that requires termination of the circuit. In response to such an anomaly detection, the systems described herein break the circuit, thus terminating current flow therethrough and suppressing any arcing event that may be occurring. However, when the continuity signal is present in the solar array signal, the systems maintain the circuit in a closed condition, allowing current to flow. Accordingly, the systems and methods described herein may be referred to as discontinuity detection and arc suppression systems, even though arc suppression is a byproduct of breaking the solar array circuit.
In embodiments where the signal on the solar array circuit 307 is monitored using an antenna 308, the amplifier 314 may be a preamplifier for the signal detected by the antenna 308. As it can be appreciated by those with skill in the art, preamplification of an antenna signal provides a more useful signal, however it is not necessary to process the signal. In an embodiment where the signal on the solar array circuit 307 is monitored using a hard-wire connection 310, the amplifier 314 may also amplify or attenuate the detected signal depending on the desired application. In both embodiments implementing an antenna 308 and/or a hard-wire connection 310, the amplifier 314 may include an operational amplifier (“op amp”) or any other amplification methods or components.
The filter 316 of the detection circuit 312 filters the detected signal after the detected signal has been amplified or attenuated by the amplifier 314. The filter 314 is used to filter the detected signal to facilitate the detection of the stimulus 304. For example, if the stimulus 304 has a relatively high frequency, the filter 316 may include a high-pass filter, thus allowing the high-frequency stimulus to pass through the filter. Depending on the application and the characteristics of the stimulus 304, a number of different filters could be implemented in the filter 316, including low-pass filters and band-pass filters, among others. Additionally, computer-implemented filtering programs, or other filtering methods and devices could be utilized.
The output 318 of the detection circuit 312 controls the output of detection circuit 312 and, in some embodiments, outputs a control signal to a switch 320. The output 318 may include circuitry to compare the filtered signal to a predetermined level to determine if the stimulus 304 is present. In such embodiments where the filtered signal is compared to a predetermined level, the output component 318 circuitry may include a comparator. Other methods and components for comparing characteristics of electric signals, such as voltage levels, current levels, frequencies, waveform shapes, etc. are contemplated. In certain embodiments where the output 318 detects the presence of the stimulus 304 within the detected composite signal from the solar array 306, the output 318 outputs a control signal to switch 320 indicating that the switch 320 should close or remained closed. In certain embodiments, the stimulus 304 is converted to a control signal by the output 318 instead of an independently generated control signal. In other embodiments, the output 318 allows for the stimulus signal to pass through to the switch 320 if the stimulus 304 is present. In such embodiments, the switch 320 will close or remain closed upon receipt of the stimulus 304. Where the stimulus 304 is not present, no signal will reach the switch, and the switch will open. Alternatively, the output 318 may continue to output a signal to the switch 320 indicating that switch 320 should remain closed for a period of time after the stimulus 304 is not detected on the solar array 306.
The switch 320 is connected to the solar array 306 in such a way that it can open the solar array circuit 307. Although the switch 320 has been depicted in
Two options for providing power to the detection circuit 312 and the switch 320 are depicted in
One example of a detection circuit 312 is depicted in
One example of a circuit for detecting a discontinuity and suppressing a current within a solar array system 600 is depicted in
The ratio of primary windings to secondary windings on the transformer 636 may be selected to produce a sufficient voltage on the secondary winding to close the switch 620. In embodiments that utilize a diode bridge rectifier, it may be desirable to implement diodes that are fast enough to handle the selected stimulus signal 604. Additionally the rectified output may be filtered prior to reaching the switch 620. Also, a capacitor may be placed across the MOSFET to allow the MOSFET to close after is has been opened. This capacitor is depicted as C2 in
Additional elements or components may be added to the system 600 as desired. Filtering and signal conditioning components between the secondary winding of the transformer 636 and the switch 620 may be used to detect if the alternating current coupled by the transformer 636 matches the stimulus signal 604. If the coupled solar array signal from the solar array circuit 607 does not match the characteristics of the stimulus signal 604, it may be filtered out, preventing the switch 620 from closing based on an incorrect signal, such as electrical noise. Also, where a MOSFET is used as the switch 620, a deadband may be added to the gate drive of the MOSFET to ensure that the MOSFET would be fully on or fully off. Adding the deadband would also prevent linear responses in the MOSFET which can cause the MOSFET to overheat. Many of the components depicted in
At operation 712, a control signal is sent to the switch indicating that the switch should close. In certain embodiments, the control signal is generated when the continuity signal is detected. In other embodiments, the control signal is the continuity signal itself, or derived therefrom. For example, where the continuity signal is present, that signal may be modified in some manner and passed to the switch as a control signal indicating that the switch should close or remain closed. In other embodiments, the control signal is rectified, as depicted at operation 714. Where the control signal is present, it may be rectified before it is passed to the switch. The rectified control signal indicates to the switch that the switch should close or remain closed.
At operation 716, the switch receives the control signal or the continuity signal indicating that the switch should be closed or remain closed. Upon receipt of the control signal or the continuity signal, the switch closes or remains closed. For example, where the switch is a MOSFET, the MOSFET receives the control signal or rectified continuity signal on its gate drive, which powers on the MOSFET to close the switch. Where the continuity signal is not present in the composite signal, no control signal will be sent. Thus, in the absence of the continuity signal, the switch will open or remain open at operation 718. By opening the switch, direct current will not flow through the solar array circuit and any potential arcs located thereon will be suppressed.
In certain embodiments, the detection and suppression systems disclosed herein may be integrated into a solar array system of BIPV or other solar articles. One detection and suppression system or circuit may be used for a single array. Alternatively, multiple detection and suppression systems may be used in a single array, for example, a detection and suppression system may be incorporated into a subset of solar cells in an array. In one embodiment, a detection and suppression system may be included in each row of a multi-row array. In multiple detection system arrays, the detectors may be configured such that detection of an arc event by a single detector may initiate arc suppression in all suppression devices.
The detection and suppression system described above may be sold as a kit, either in a single package or in multiple packages. A kit may include the various components described above in the various systems, or each of these components may be sold separately. Each system includes a plurality of connectors for communication with the other components of the array. If desired, wiring may be included, although instructions included with the kit may also specific the type of wiring required based on the particular installation. Additionally, systems may be loaded with or include the necessary software or firmware required for use of the system. In alternative configurations, software may be included on various types of storage media (CDs, DVDs, USB drives, etc.) for upload to a standard PC, if the PC is to be used as the array performance monitor, or if the PC is used in conjunction with the array performance monitor as a user or service interface. Additionally, website addresses and passwords may be included in the kit instructions for programs to be downloaded from a website on the internet.
In its most basic configuration, operating environment 800 typically includes at least one processing unit 802 and memory 804. Depending on the exact configuration and type of computing device, memory 804 (storing, among other things, continuity signal parameters and/or instructions to provide control signals described herein) may be volatile (such as RAM), non-volatile (such as ROM, flash memory, etc.), or some combination of the two. Memory 804 may store computer instructions related to, inter alia, provide system control signals, continuity detection parameters, etc., as disclosed herein. Memory 804 may also store computer-executable instructions that may be executed by the processing unit 802 to perform the methods disclosed herein.
This most basic configuration is illustrated in
Operating environment 800 typically includes at least some form of computer readable media. Computer readable media can be any available media that can be accessed by processing unit 802 or other devices comprising the operating environment. By way of example, and not limitation, computer readable media may comprise computer storage media and communication media. Computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Computer storage media includes, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information. Communication media embodies computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, RF, infrared and other wireless media. Combinations of the any of the above should also be included within the scope of computer readable media.
Control instructions for operating the detection and suppression system may be stored in system memory 804. Processing unit 802 may execute control instructions to provide the desired stimulation. The operating environment 800 may be a single computer operating in a networked environment using logical connections to one or more remote computers. The remote computer may be a personal computer, a server, a router, a network PC, a peer device or other common network node, and typically includes many or all of the elements described above as well as others not so mentioned. The logical connections may include any method supported by available communications media. Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets and the Internet.
In embodiments, the various systems and methods disclosed herein may be performed by one or more server devices. For example, in one embodiment, a single server, such as server 824 may be employed to perform the systems and methods disclosed herein. Client device 822 may include one or more of the implant, the remote device, or the external interface unit, which may communicate with each other using one or more of network 828 and servers 824 and 826.
In alternate embodiments, the methods and systems disclosed herein may be performed using a distributed computing network, or a cloud network. In such embodiments, the methods and systems disclosed herein may be performed by two or more servers, such as servers 824 and 826. Although a particular network embodiment is disclosed herein, one of skill in the art will appreciate that the systems and methods disclosed herein may be performed using other types of networks and/or network configurations.
While there have been described herein what are to be considered exemplary and preferred embodiments of the present technology, other modifications of the technology will become apparent to those skilled in the art from the teachings herein. The particular methods of manufacture and geometries disclosed herein are exemplary in nature and are not to be considered limiting. It is therefore desired to be secured in the appended claims all such modifications as fall within the spirit and scope of the technology. Accordingly, what is desired to be secured by Letters Patent is the technology as defined and differentiated in the following claims, and all equivalents.
This application is being filed on 26 Jun. 2013, as a PCT International Patent application and claims priority to U.S. Patent Application Ser. No. 61/669,415 filed on 9 Jul. 2012, the disclosure of which is incorporated herein by reference in its entirety.
Filing Document | Filing Date | Country | Kind |
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PCT/US2013/047841 | 6/26/2013 | WO | 00 |
Number | Date | Country | |
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61669415 | Jul 2012 | US |