WO2007006564A2 - Device for monitoring photovoltaic panels - Google Patents

Abstract

The invention relates to a device for monitoring photovoltaic panels in the event of theft or damage. The aim of the invention is to provide a solution that, without a predetermined action of nominal current, furnishes a signal by a monitoring of direct current voltage in the event of damage or theft. To this end, the invention provides that a window comparator with programmed reference voltage divides the residual voltage of the photovoltaic panels, which is given at twilight or night, into three categories: outside, inside and below and, per panel, a coded signal typical for a panel is sent to a central alarm device, which is located next to the inverter and which has a decoder that sets off a panel-specific alarm in the event the signal indicates below.

Description

"Device for monitoring photovoltaic panels"

The invention relates to a device for monitoring photovoltaic modules in the event of theft or damage by the evaluation of residual voltage signals.

The prior art is given by the utility model G 94 11 783.7, in which a current source with a predetermined rated current is applied to the power current line by a suitable device when falling below a defined voltage. This approach has the disadvantage of the consumption of electrical power for small, especially large photovoltaic systems.

The object of the invention is to find a device that delivers a signal without DC voltage application through a DC monitoring in case of damage or theft.

This object is achieved according to the invention by a device having the features of claim 1.

Large photovoltaic systems are usually constructed in such a way that a certain number of solar panels are connected in series in order to achieve the voltage required for the inverter and lead these power power lines via equipment connection boxes (GAK) to the inverter. These device connection boxes with a control cable to the inverter are suitable for receiving the quiescent current monitoring according to the invention.

If the system is disconnected from the grid and the inverter due to low energy input, it still is there is enough voltage that can be used for monitoring. On a moonless night, the luminance is 0.0003 lux, while moonlight converts 0.2 lux into energy. In addition, the remaining sky lighting is provided by "Lichtverschirmtzung".

This residual brightness produces a low electrical voltage, which can range from a few hundred millivolts to a few volts / GAK. Since the cables are galvanically isolated from the solar modules to the inverter, ie high impedance, this voltage can be used to monitor the entire system.

According to the invention, a window comparator is used, which evaluates the following criteria and is installed in each GAK:

1. If the solar module is in operation during the day, a high voltage is created. In the monitoring device, here called the window comparator; the signal "window outside" is activated and the system is switched on, in which a relay attracts the panels with the solar modules galvanically switched through to the inverter.

2. If the generated voltage drops below a value set during installation of the system during twilight and at night, the window comparator will reach the threshold "window within". The output of the window comparator "window outside" is deactivated and the relay for connecting the panels to the inverter drops off and opens this circuit.

3. The signal "window within" reaches the encoder, in which a clear assignment to the respective GAK is determined. is laid. The generated signal is forwarded to the decoder and to the central evaluation device via a line secured by closed-circuit current.

4. If the central evaluation unit is reached by the coded signals of the coders in the GAKs, then the respective GAKs and thus the respective panels of solar modules are signaled as "OK".

5. If the residual voltage generated by the solar panels falls to zero volts, the output "window below" is activated. An alarm is triggered via the signal line from the encoder to the decoder and on to the evaluation unit.

6. The signal transmission path is protected by a normally closed contact (Ük) in the GAK, which is located in the housing of the GAK, in which the contact drops when the GAK's housing is opened and the closed circuit is interrupted.

This ensures continuous monitoring for all operating states of the system, since all GAKs are included in the system and an alarm can be triggered by the alarm device with panel accuracy.

A separate monitoring of the solar panels during operation with the inverter is not necessary, since a fault signal is automatically generated in case of power loss.

The additional power supply for this protection device, where at fixed intervals a signal from the encoder in the GAK to the decoder in the central alarm device requires a few milliwatts, which are taken from a small battery and which is fed by the live conductors to the inverter during operation or can be ensured by remote feeding through the control cables.

The monitoring device consists of:

1. individual solar panels

2. which are connected in series to the GAK

3. the monitoring device in the individual GAK's

4. the power supply from the panels to the GAK

5. the power forwarding to the inverters

6. the switching relay to the inverters

7. the surge protector for the window comparator

8. the window comparator with programmed reference voltage

9. the encoder

10. the line to the evaluation unit

11. the quiescent power line to the evaluation unit

12. the normally closed contact in the closed circuit in the GAK

13. the central alarm device in the inverter

14. the decoder

15. the quiescent current monitoring

16. the evaluation and reporting device

17. the inverter

18. the battery buffer of the monitoring device

The device is shown in the drawing.

Solar systems for operation with the invention consist of a series of solar panels 1, of which a certain number are connected in series and connected to a device connection box 2. A variety of such Terminal boxes 2 is connected in parallel and connected to an inverter 17, which generates a usable AC voltage from the DC voltage generated by the solar panels. The number of solar panels 1 connected in series is selected such that the resulting voltage for the inverter 17 can be used.

A monitoring device 3 according to the invention is integrated in each of the device connection boxes 2. The solar panels 1 are connected via the terminal 4 with the monitoring device. The terminal 5 is used for power transmission to the inverter 17. A switching relay 6 can connect the solar panels 1 to the inverter 17 in response to a control pulse.

To monitor the panel voltage, a window comparator 8, which is connected to the panel terminal 4 with the interposition of an overvoltage protection 7, is used. A reference voltage can be set at the window comparator 8.

The comparator result of the window comparator 8 can be fed via a coder 9 via a line 10 to a central alarm device 13, with a quiescent current 11 having a normally closed contact 12 being additionally provided for increasing safety, by means of which manipulations on the control line 10 can be detected. A battery buffer 18 is provided to provide power to the entire monitoring device 3 when the solar panels 1 do not generate sufficient energy.

The evaluation unit 13 includes a decoder 14 for the signals of the encoder 9 and a quiescent current monitor 15 which monitors the signal lines for tampering attempts with the quiescent current line 11 and the normally closed contact 12. Furthermore, an evaluation and reporting device 16 is provided which evaluates the interference signals generated by the decoder 14 and the quiescent current monitoring 15 and, if necessary, triggers an alarm.

The monitoring device works as follows:

If enough light on the solar panels 1, so that they generate a sufficiently high utility voltage, it is detected by the window comparator 8 as lying above the upper limit and the relay 6 is switched so that the voltage is applied to the inverter 17 and energy is generated. If manipulation attempts are made on the solar panels 1 in this operating state, the generated power drops and a warning signal is generated.

In the event that no sufficient useful voltage is generated at night or in heavy cloud, when switching below a threshold value of the window comparator 8, the switching relay 6 is released and so the solar panels 1 separated from the inverter 17. Also in this case, a residual voltage is generated by the solar panels 1 due to various residual light influences on the opened by the switching relay 6 high-resistance connection. This is detected with the window comparator 8 and forwarded via the encoder 9, a corresponding signal to the monitoring and reporting device 13.

If there is a line interruption due to manipulation or theft attempts on the panels 1, the residual voltage drops significantly, as detected by the window comparator 8 and a corresponding signal is forwarded via the encoder 9 to the monitoring device 13, which triggers an alarm signal in the sequence. Certain fluctuations in the panel voltage about the adjustable reference value are tolerated by the window comparator 8, without an alarm signal is triggered or the switching relay is turned on again before reaching a minimum voltage. In this way, manipulations on the panels can be reliably detected. Since a device connection box is usually equipped in each case with a monitoring device according to the invention, precise assignments to individual panel groups are possible even with larger systems.

Additional safety features the Rühestromüberwachung, which also in case of manipulation of supply lines u. like. Trigger alarm signals.

Of course, the invention is not limited to the above embodiment, but can be modified in many ways without departing from the spirit. Thus, in particular the design of the individual modules and their technical realization is variable and the addition or integration in other monitoring devices possible.

Claims

Claims: 1. A device for monitoring photovoltaic panels in the event of theft or damage, characterized in that a window comparator with programmed reference voltage divides the given at dusk or night residual voltage of the photovoltaic panels in the three categories outside, inside and below and divides each panel a panel typical coded Signal is sent to a located at the inverter central alarm device with decoder, which triggers in the case of the signal below a panel-related alarm. 2. Device for monitoring of photovoltaic panels in the event of theft or damage, characterized in that the on the inverter leading lines switched window comparator has an overvoltage protection in front of the window comparator. 3. A device for monitoring of photovoltaic panels in the event of theft or damage, characterized in that the window comparator and the coding unit is powered by a battery buffer with power and the battery buffer is fed during the day by the lines leading to the inverter. 4. Device for monitoring of photovoltaic panels in the event of theft or damage, characterized in that the device located in the terminal box device are protected from overvoltage contactor, window comparator and encoder quiescent current and when opening the housing, the quiescent current is interrupted.