DE102006049285A1 - Solar panels monitoring method for solar system, involves operating power semiconductors in boxes, which serve electrical connection of panels, in conducting direction, and monitoring current flowing through series connection of panels - Google Patents

Abstract

The method involves applying a voltage, which is larger than an output voltage of a solar system, with a reverse polarity, in a series connection of solar panels (2), when the output voltage falls below a pre-determined threshold voltage within a range of 1 to 60 volts. Power semiconductors provided in boxes, which serve the electrical connection of the panels, are operated in a conducting direction. Current, which flows through the series connection of the panels, is monitored. An independent claim is also included for a circuit for implementing a method for monitoring solar-panels in a solar system against theft.

Description

The The invention relates to a method for monitoring solar panels in solar systems on theft and the associated circuit.

in view of Increasing pollution gains the use of renewable energy sources, especially the water, wind and solar energy, more and more important. This was the performance of solar modules have been significantly improved in recent years. Furthermore Solar systems are virtually maintenance-free, easy to use and the modular design of solar systems enables flexible design the plant sizes and services, so that small to large consumers are supplied can.

Of the modular layout of the plants but has, compared to the compact Installations for wind and water energy use, the disadvantage that the individual solar modules relatively easy stolen and resold can be. favoring it is that solar systems often outside the metropolitan areas be operated, so that a guard around the clock practically not possible is. To protect against theft are therefore in the conventional Solar systems either fences or housing and castles for the Solar panels used. For Effective protection must be this but executed massive could be but still relatively easily broken up by mechanical means become. Modern facilities can the theft of panels during recognize the operation of the system by their power loss. Already off that's why solar panels are usually stolen at night, especially during the day, the occurring voltage flashover unwanted Attract attention and the risk of an electric shock consists.

In EP 1 125 352 B1 describes a protection system for a solar module against theft and use by an unauthorized consumer. For this purpose, according to the proposal, there is an interruption device on the solar module and, on the consumer side, in the case of larger systems on the inverter, a release device. The interrupt device sends the enabling device a first signal code and interrupts the power transmission to the consumer if it does not receive a response signal code from the enabling device within a predetermined time. Consequently, the panel can not be used without the appropriate release device. In addition, it is proposed to attach the interruption device to the solar panel in such a way that attempting to remove it makes the solar panel unusable. This is to make the solar panel for the thief worthless.

Despite considerable progress, the protection system has been designed accordingly EP 1 125 352 B1 but still some disadvantages. So it is questionable whether the interruption device can not be bypassed or removed, especially since there is no time pressure after the theft. Furthermore, each solar panel must be equipped with the appropriate box, which, especially in larger solar systems, causes significant costs.

With regard to the detection and localization of faults in photovoltaic systems, in DE 93 12 710 U1 describes a modular diagnostic system based on the principle of impedance measurement of solar panels. However, the implementation of theft monitoring is not encouraged.

In DE 10 2006 027 104.1 discloses a junction box for solar panels, with which the heat generated in the protective diodes, MOSFETs or other corresponding power semiconductors, which serve as a bypass in the event of partial shading of the panels, heat is well dissipated. At the same time a method for the regular monitoring of the function of these semiconductors is presented. In addition, it is proposed that failures of these semiconductors caused by their interruption or short circuit be indicated either by acoustic or optical signaling devices or transmitted by radio, bus systems, Aufmodulierung or other transmission methods in a central office. A theft can not be detected promptly with this solution.

Of the Invention is based on the object by a method that only one circuit unit per solar system needed, every single solar panel, both at night and during monitor the output of the solar system from theft. The circuit unit is intended for be usable for every type of plant; monitor. The circuit unit should for be usable for every type of plant; at the same time, existing facilities should thus easy to retrofit be.

These The object is achieved by the characterizing features of claims 1 and 2 solved. advantageous versions the circuit are from the claims To take 3 to 7.

According to the invention, a voltage with a reverse polarity compared to the output voltage of the system is applied at night to the series connection of the solar panels. Thus, the Schottky diodes or the corresponding power semiconductors are operated in the forward direction ben. As a criterion, when the so-called Reversspannung is applied, the current output voltage of the solar system is used. At night, for example, this drops from approx. 1000 V to almost 0 V. The Reversspannung is therefore applied when falling below a defined voltage limit in the range of 0-60 V, typically 42V. With a choice of voltage limits less than or equal to 42 V in night mode, it is always ensured that the system is operated in the area of the safety voltages.

ever according to the type of inverter used, this is before applying the Reversspannung separated from the solar system or not. If the inverter outputs greater interference voltages in the reverse voltage mode or on the input side leakage currents caused, it must be separated in any case.

According to the invention is in Reverse voltage operation to interruptions caused by theft to recognize the current through the series connection of the panels flows, monitors. Since the solar cells in the reverse direction and the power semiconductors, or protective diodes are connected in the forward direction, the Series connection in the theft of panels electrically by removal the power semiconductor interrupted. However, because the solar panel forms a structural unit of solar cells and power semiconductors, In the case of a theft, the power semiconductors are inevitably removed.

at the usual today Solar systems with plastic junction boxes in which the protection diodes are located, the series connection of the panels can either due to theft or even a blown-off protective diode to be interrupted. A distinction is by the time to which the failure is reported, possible. The protection diodes can only while of the power operation of the solar system. Consequently, will the alarm immediately upon application of the Reversspannung, i. when switching in the night mode, reported. If the alarm occurs at a different time on, it is very likely to be one Theft; otherwise, for the interruptions for example, influences such as Bad weather or marten bite be. The theft of a solar panel during power operation of the Plant is also detected because when removing a solar panel the solar system due to the power loss caused thereby automatically switches to night mode. This will prevent theft activated.

The inventive method can be used in a particularly advantageous manner in combination with the in DE 10 2006 027 described connection boxes are operated. Since both methods create a reverse voltage in night mode, the corresponding module can be shared. In addition, false alarms are avoided due to blown protective diodes, since only in the case of theft, a message is triggered. If the protective diodes burn out, the affected panel is indicated by the illumination of a light-emitting diode at the associated connection box.

The Circuit for monitoring of solar panels in solar panels on theft consists of a test module, which serves to apply the Reversspannung in night or rest mode, a power monitoring device and an alarm unit.

A advantageous embodiment of the test module composed of a power source and a voltage measuring device. The measuring device switches the power source in night mode, d. H. if the output voltage of the solar system is a voltage limit of about 42 V below. Optionally, the test module can also be equipped with a relay simultaneously with the power the power source the inverter from the series connection of the solar panels separates. It is advantageous to the normally closed contact of the relay use, because then no power losses during operation of the solar system occur and as well the solar system even when - but extremely rare - failure of the test module continue without interruption can be operated.

The Power Management is in a cost effective Variant of a resistor connected to the series connection of the solar panels is connected in series and a voltage comparator circuit with Switching relay constructed, which monitors the voltage drop across the resistor. If the voltage drops in an interruption of the series connection of the panels under a certain value, the voltage comparator circuit switches that Relay. The potential-free switching contact of the relay is an alarm signaling device connected. This can be an acoustic or optical as needed Message, a silent alarm about Radio, via the Internet or by a telephone call.

With the circuit according to the invention can Solar systems of every type and size or retrofitted become. In any case, only one central circuit is needed built in a small space and equipped with cost-effective components. The circuit is either designed as a separate device or in the inverter or the disconnector integrated.

If the inverter used in Reversspannungsbetrieb no major Störspannun gene outputs or causes leakage currents on the input side, and the comparatively expensive special relay for the separation of the inverter can be saved and the associated voltage drop across the contacts of the relay can be avoided. On the other hand, due to this voltage drop only power losses of typically two to four watts, which are usually negligible. In addition, it is conceivable to carry out the DC isolation of the solar system from the inverter via this relay and thus replace the commonly used DC circuit breaker.

The The invention will be explained in more detail with reference to an embodiment; For this demonstrate:

1 : the block circuit for single-panel monitoring with anti-theft device

2 : the wiring diagram.

Out 1 it can be seen that the series connection of the solar panels 2 which are essentially electrically from the Schottky diodes 1 and the solar cells 3 is constructed in day mode via the relay 6 with the inverter 4 are connected. In night mode, the system is connected to the relay 6 disconnected from the inverter. At the same time the power source 7 of the test module 5 switched on. As a result, a current flow in the direction opposite to that in the daytime operation of the plant takes place.

The tension, the resistance 8th leading to the series connection of the solar panels 2 is connected in series, drops, is connected to a voltage comparator circuit 9 supervised. Become one or more solar panels in night mode 2 removed by theft, the current flow is interrupted and the resistor 8th As a result, no voltage drops. The voltage thus falls below one in the voltage comparator 9 set minimum voltage value and the potential-free contact 11 of the relay 10 will be closed. This will over the theft alarm system 12 an optical or acoustic alarm or a silent alarm triggered via the Internet, by phone or by radio.

A corresponding circuit diagram is in 2 shown. The circuit is divided into two circuit units. Behind the power switch, fuse and overvoltage protection is a transformer with a high insulation rating, typically greater than 2 kV, which powers the two circuit units through two separate secondary windings, each branch being grounded separately.

The first circuit unit, the so-called Stromprüf generator, is as a power source trained, which has a sufficient voltage reserve, up to to 20 panels each with 3 bypass diodes including the cable routes typically over To feed 100 m with approx. 20 mA direct current. After the rectification and filtering the transformer-secondary rated voltage of 30 V AC, R1 limits the total current and T1 switches the switched as a current source linear regulator 1 a. About the two series-connected high-voltage diodes D5 and D6, the test current in Lapel direction on the positive and negative pole of the series switched solar panels (panel chain) guided, goes through the panel chain and generates over the series resistor R3 a voltage drop, which via T3 the Switching transistor T4 blocks. If the panel chain is interrupted in case of theft, then T4 goes through, relay 2 picks up, red LED1 lights up and the potential-free alarm contacts are closed. All of them can do this potential Types of alarms are triggered.

The first circuit unit is only put into operation when the optocoupler OK1 activated by the second circuit unit and thus the current source of the first unit through the transistor T1 is turned on.

The second circuit unit is the so-called comparator unit. After rectification and screening of the transformer-secondary rated voltage of 24 V AC is the DC voltage with the help of the linear regulator LR2 stabilized to 24 V DC. This voltage supplies the Bipolar comparator IC1, the relay load circuit and the control of the Optocoupler OK1 and the green LED LED2. Located at the inverting input of the comparator the panel voltage to be detected, for safety reasons, in particular to protect against rollovers, by a 5-part resistor is divided down. At the non-inverting input is a precision reference voltage at. This is done using the power controller LR3 and an adjustable Voltage dividers formed. This allows panel voltage ranges from 30 to 1000 V DC detect or compare. Will P1 adjusted so that a voltage of about 1 V at the pin3 of the comparator IC1 is present, then the comparator switches when falling below a Panel voltage of approx. 42 V the load circuit and thus the relay 1 on and T2 is turned on. As a result, the PNP transistor controls T5 and activates the LED2 and the optocoupler OK1, so that the Circuit unit 1 activated.

For certain types of inverters that are used in the solar panels, the relay 1 can be omitted. Otherwise, the relay 1 disconnects the positive line between the panel chain and the inverter and the reverse test current flows only through the panels, or their bypass Dio the. It is important that the relay can only switch when a panel voltage of less than 42 V is detected. This case is safely achieved when darkness falls and the performance of the panels is then almost zero.

1

Schottky diode

2

Solar Panel

3

solar cell

4

inverter

5

test module

6

disconnectors

7

voltage source

8th

series resistance

9

voltage

10

relay

11

floating Contact

12

Theft alarm notification system

Claims (7)

Method for monitoring solar panels in solar systems for theft, characterized in that, when the output voltage of the system falls below a predefined voltage limit in the range of 1 to 60 V, a greater voltage with respect to the output voltage with the opposite polarity to the series connection of the solar Panels ( 2 ) is applied, whereby power semiconductors in boxes, which serve the electrical connection of the panels are operated in the forward direction, and the current flowing through the series connection of the panels, is monitored. Circuit for carrying out the method according to claim 1, characterized in that it consists of a test module ( 5 ), the application of the voltage to the series connection of the solar panels ( 2 ) with a polarity reversed in relation to the output voltage of the solar system, a current monitoring device and an alarm signaling unit ( 12 ) is constructed. Circuit according to Claim 2, characterized in that the test module ( 5 ) from a power source ( 7 ) and a voltage measuring device, which the power source ( 7 ), if the output voltage of the solar system falls below a predefined voltage limit. Circuit according to Claims 3 and 4, characterized in that the test module ( 5 ) a relay ( 6 ), which simultaneously with the switching on of the voltage source ( 7 ), the inverter ( 4 ) is electrically isolated from the series connection of the solar panels. Circuit according to Claim 5, characterized in that the relay ( 6 ) has one or more NC switch contacts, which the inverter ( 4 ) disconnect from the solar system. Circuit according to Claims 3 to 6, characterized in that the current monitoring device consists of a resistor ( 8th ) connected to the series circuit of solar panels ( 2 ) is connected in series and a voltage comparator circuit ( 9 ) measuring the resistance ( 8th ) voltage drop, and a relay ( 10 ) consists. Circuit according to Claims 3 to 7, characterized in that the potential-free switching contact ( 11 ) of the relay ( 10 ) with an alarm signaling unit ( 12 ), which can emit an audible or visual message or trigger a silent alarm via radio, the Internet or by a telephone call.