Enhanced system and method for theft prevention in a solar power array during nonoperative periods
Solar panel theft protection system operable both during daytime and nighttime. Power is feed into a solar array system sufficient to operate local management units. The units monitor solar panels; in the event that a panel is disconnected, an alarm is set off.
1. A photovoltaic system comprising:
a solar array having:
at least one solar panel, and
at least one respective local management unit (LMU) coupled with the at least one solar panel;
an inverter;
a set of DC wires connected between the at least one solar panel and the inverter;
a power supply configured to provide power to the at least one LMU during a time period in which the solar array is not producing power; and
a controller coupled between the set of DC wires and the power supply, the controller configured to:
provide power from the power supply to the set of DC wires during the time period in which the solar array is not producing power, and
suppress false starts of the inverter caused by the power provided from the power supply via the controller to the set of DC wires;
wherein the respective LMU is configured to receive the power provided from the power supply via the controller and the set of DC wires when the solar array is not producing power;
wherein the respective LMU is configured to maintain a specified pattern of communication with the controller; and
wherein, if the specified pattern of communication ceases between the respective LMU and the controller after zero or more attempts by the controller fail to reestablish the specified pattern of communication with the respective LMU, the controller is configured to raise an alarm.
2. The system of claim 1 wherein the controller is selected from the group consisting of:
a master management unit;
a theft prevention controller; and
a combination of a master management unit and a theft prevention unit.
3. The system of claim 1 wherein the communication comprises a secure communication.
4. The system of claim 1 wherein the power supply obtains power from at least one source selected from the group consisting of:
a grid;
a battery; and
a capacitor.
5. The system of claim 1 wherein the respective LMU is not operating until it receives a wake up signal from the controller or a wake up signal from a clock internal to the respective LMU.
6. The system of claim 1 wherein the controller confirms the communication with the respective LMU by periodically polling the respective LMU.
7. The system of claim 1 wherein the controller confirms the specified pattern of communication with the respective LMU by monitoring current flow between the power supply and the solar array for a select pattern.
8. The system of claim 1 , wherein:
the respective LMU is configured to determine whether the solar panel becomes disconnected from the solar array or the solar panel becomes inoperable; and
in response to a determination that the solar panel becomes disconnected from the solar array or the solar panel becomes inoperable, the respective LMU sends a notification to the controller.
9. The system of claim 8 , wherein the determination that the solar panel becomes disconnected from the solar array or the solar panel becomes inoperable is made by detecting at least one of: a change in resistance, and a change in capacitance between the solar panel and the respective LMU.
10. The system of claim 8 , wherein, upon receiving the notification by the controller, the system raises an alarm.
11. The system of claim 8 wherein the controller is selected from the group consisting of:
a master management unit;
a theft prevention controller; and
a combination of a master management unit and a theft prevention unit.
12. The system of claim 8 wherein the notification comprises a secure message.
13. A method for operating a photovoltaic system comprising:
exchanging periodic messages between a local management unit (LMU) and a controller, wherein the LMU is connected to an inverter via a set of DC wires configured to transmit, to the inverter, power generated by a respective solar panel coupled with the LMU;
providing, by the controller, an auxiliary voltage to the set of DC wires to power the LMU when the photovoltaic system is not producing power for the inverter;
suppressing, by the controller, false starts of the inverter caused by the auxiliary voltage;
upon a failure of the controller to receive a specified pattern response to one or more of the periodic messages, attempting by the controller to reestablish a communication with the LMU by sending zero or more poll messages; and
upon the controller failing to reestablish the communication, raising an alarm.
14. The method of claim 13 wherein the controller is selected from the group consisting of: a master management unit; a theft prevention controller; and a combination of a master management unit and a theft prevention unit.
15. The method of claim 13 wherein the periodic messages comprise a secure communication.
16. The method of claim 13 , further comprising:
monitoring, by the LMU, the respective solar panel; and
upon a failure of the respective solar panel to maintain an electrical connection with the LMU, sending by the LMU a notification to the controller.
17. The method of claim 16 wherein a determination that the respective solar panel has failed to maintain the electrical connection with the LMU is made by detecting one of: a change in resistance, and a change in capacitance between the solar panel and the LMU.
18. The method of claim 16 , wherein, upon receiving the notification by the controller, the system raises an alarm.
19. The method of claim 16 wherein the controller is selected from the group consisting of:
a master management unit;
a theft prevention controller; and
a combination of a master management unit and a theft prevention unit.
20. The method of claim 16 wherein the notification comprises a secure message.