WO2014082844A1

WO2014082844A1 - Control of solar tracker device

Info

Publication number: WO2014082844A1
Application number: PCT/EP2013/073497
Authority: WO
Inventors: Martin Ziegler; Ünver SENOL; Johannes WÜLLNER
Original assignee: Soitec Solar Gmbh
Priority date: 2012-11-28
Filing date: 2013-11-11
Publication date: 2014-06-05
Also published as: FR2998684B1; ES2655550T3; US10627136B2; EP2926061B1; US20150338131A1; CN104813116B; EP2926061A1; CA2930646C; FR2998684A1; CN104813116A; CA2930646A1

Abstract

The present invention relates to a method for controlling a tracker control unit and therefore the tracker device of a solar module of a solar power plant, wherein the tracker device comprises a control unit, an actuator element and a support means for supporting the solar module, comprising the steps of detecting a particular event, interrupting for a predetermined time period power supply to the control unit of the tracker device in reaction to the detection of the particular event, resuming power supply after the predetermined time period and in reaction to the resumed power supply actuating the support means by the actuator element to move the support means into a predetermined position.

Description

Control of Solar Tracker Device

Field of Invention

The present invention relates to a central safety system for solar tracker devices and their tracker control units in a solar power plant.

Background of the invention

Solar energy systems comprise solar modules including solar cell arrays. In order to enhance efficiency of the energy conversion of solar modules apparatuses for tracking the modules to the current position of the sun are known in the art. The tracker apparatuses are provided for optimizing the electrical output power of the solar modules by following the path of the sun crossing the sky or by employing calculation of ephemerides. Two-axes trackers allow for angular motion of the solar modules about the horizontal axis ("tilt") and angular motion about the vertical axis ("rotation").

Tracker apparatuses are necessary in concentrator photovoltaic (CPV) systems wherein they can guarantee that the solar radiation impinges (almost) vertically on the concentrator optics. A typical tracker apparatus comprises a tracker table or frame on which the photovoltaic module is mounted, mechanical actuators (e.g., electrically driven motors) for adjusting the tracker table and a (vertical) column or rod for holding the actuators and the tracker table. In particular dangerous circumstances, e.g., heavy winds or gusts or a power breakdown of the electrical grid, the tracker table has to be moved into a "safety position", i.e., basically horizontally, in order to prevent any damage done to the tracker table and the mounted photovoltaic module. In the art, central communication systems control the tracker apparatus to change the tracker table to a safety posi- tion by means of communication lines. Moreover, it is known to connect the actuators of the tracker apparatus directly to a control unit such that the latter is able to directly cause the actuator to make the tracker table moving into the safety position. However, such conventional system demands for expansive line routing and, in addition, may suffer from line breakage. If, for example, a communication line connection between a tracker control unit and the central communication system fails, the tracker table will not be brought into the safety position in case of danger or, as a means of precaution, will be operated to be in such a position in any case, i.e., usually without any actual risk of damage due to environmental effects, thereby reducing power production. Thus, it is a problem underlying the present invention to provide a central safety system for the photovoltaic systems that reliably causes the tracker device to move into a safety position in case of danger without the need for a complex and expensive as well as error prone line routing.

Description of the Invention

The above-mentioned problem is solved by the method for controlling a tracker device of a solar module of a solar power plant, wherein the solar power plant comprises a central safety system and wherein the tracker device comprises a control unit, an actuator element and a support means for supporting the solar module, comprising the steps of detecting a particular event; interrupting for a predetermined time period power supply to the (control unit of the) tracker device in reaction to the detection of the particular event (by the central safety system); resuming power supply after the predetermined time period (initiated by the central safety system comprised in the solar power plant); and in reaction to the resumed power supply (and, thus, in reaction to the detected particular event) actuating the support means by the actuator element to move the support means (and thereby the solar module) into a predetermined position.

Herein, the control unit of the tracker device is also named tracker control unit. In par- ticular, all tracker devices of the solar power plant can be controlled as described above.

The solar module comprises an array of solar cells and, in principle, can be any solar module known in the art. In particular, the solar module may employ some concentra- tor optics comprising mirrors and/or lenses for focusing solar rays to the solar cells. The support means for supporting the solar module can be a tracker table or some frame comprising bars for mounting the solar module. The bars can be horizontal and/or vertical bars. The particular event can be any event of danger, for example, a predetermined threshold for a wind velocity measured in the vicinity of the solar module or somewhere else being exceeded. Other events of danger comprise a power breakdown of the electrical grid, in particular, the electrical grid wherein power gained by the solar power plant is fed or the electrical grid used for operation of the solar power plant, or some failure of a control system controlling crucial parts of the solar power plant.

The particular position can particularly be a position in that the support means (and thereby the solar module) is oriented substantially horizontally. By "substantially" horizontally, in particular, a position with an angle of the main plane of the support means (solar module) to a vertical axis that is perpendicular to an essentially horizontally oriented ground plane whereupon the tracker device is installed of between 70° to 1 10° and more particularly 80° to 100° or 85° to 95° is covered. In particular, by "substantially" horizontally a position essentially parallel (within some ± 20°, in particular, some ± 10°, more particularly, some ± 5°) to the ground whereupon the tracker device is installed is covered. The support means can be mounted on a vertical column (which may be rotatable) and in this case "substantially" horizontally covers a position wherein the support means is inclined to the vertical column within a range of angles of 70° to 1 10° and more particularly 80° to 100° or 85° to 95°.

For other particular events, as for instance snow fall or hailstorm, the particular position can particularly be oriented substantially vertically in order to avoid and reduce the impact on solar modules.

The predetermined time period of interruption of electrical power supplied to the tracker device, in principle, can arbitrarily be chosen and can be in the range of some seconds or minutes (depending on the used control unit of the tracker device), in par- ticular, of about 1 to 5 seconds.

The interruption and resumption of the electrical power supply causes the tracker device to move the support means (and, thus, the solar module mounted thereon) into the particular position, in particular, the safety position in order to prevent damage of the solar module or avoid unnecessary operation of the same (for example, in the case of a power breakdown of the electrical grid wherein electric energy generated by the solar plant shall be fed). Thus, indispensable power lines can be used for communicating the emergency signal to the control unit of the tracker device that has to move the support means into the particular position. Operation of the solar tracker devices does thus not depend on a communication via a communication line between a central communication system and the tracker control unit.

Different from the art there is no risk that communication between the central communication system and the control unit of the tracker device fails due to some breakage of a communication line provided for transferring control signals from the central communication system to the control unit of the tracker device. In fact, no separate communication lines are necessary for causing the tracker device to move the support means into the particular position. Usage of the power lines represents a very reliable way of informing the tracker device that it has to move the support means into the par- ticular position. For this, the control unit of the tracker device has to be configured to understand the information included in the interruption and resumption of electrical power supply. This can easily be realized by a standard corresponding control means / receiving means provided in the control unit of the tracker device and which is configured for receiving (and interpreting) information on the interruption/resumption of the power supply, for example.

The step of detecting the particular event can be performed by means of a plurality of sensors, in particular, comprising air speed meters (anemometers), of the solar power plant. The solar power plant may have a plurality of solar modules provided with individual tracker devices and air speed meters. The central safety system can receive data from all of the air speed meters and accordingly cause interruption of power supply to one or more of the control units of the tracker devices in response to the data received from the air speed meters.

Whereas the inventive method according to the above examples operates without the need for an additional communication between a central communication system and the control unit(s) of the tracker device(s), in very sensible applications it may be pre- ferred to have an additional communication path via a communication system comprising separate communication lines (different from the power supply line to the tracker device). Thus, according to an embodiment the method further comprises sending a control signal to the tracker device comprising the actuator element over a communication line in reaction to the detection of the particular event. The control sig- nal causes the tracker device to move the support means by the actuator element in order to move it into the predetermined position. Thereby, redundancy of providing information on the particular event to the tracker device(s) is achieved and the particular position will be adopted with even higher reliability as compared to the case that is restricted to communication via power supply interruption only. The employed central communication system may particularly comprise or consist of a Supervisory Control and Data Acquisition (SCADA) system.

The predetermined time period of interrupting the power supply should be chosen such that some unintentionally occurring power breakdown is not misinterpreted at the tracker device side. Short power breaks may happen accidentally and it may be desirable not to cause the tracker device to move the support means into the particular position in response to an accidental power break. According to a variant, the inven- tive method comprises repeating the sequence of interrupting power supply to the tracker device for a predetermined time period and resuming power supply after the predetermined time period and in this variant the support means is actuated by the actuator element to move the support means into the predetermined position after the repetition of the sequence. By repeating the steps of interrupting and resuming the power supply to the tracker device it can reliably be avoided that an accidental power break of the power supply to the tracker device results in an unwanted movement of the support means and, thus, the solar module, into the particular position.

The solar power plant may comprise a backup power supply to be activated in case of a failure of power supply to the solar power plant that is necessary for the operation of the same. In particular, the method according to one of the above-described example may further comprise activating a backup power supply for supplying power to the tracker device in reaction to the detection of the particular event or in reaction to a detected different event.

The above-mentioned problem is also addressed by a solar power plant, comprising at least one solar module or solar mirror mounted on a support means; a tracker device configured for moving the support means (and thereby the solar module) by means of an actuator element and comprising a tracker control unit configured to control the tracker device; a power supply means configured for supplying power to the tracker device; at least one sensor configured for detecting a particular event; a central safety system configured for interrupting the power supply from the power supply means to the control unit of the tracker device for a predetermined time period in reaction to the detection of the particular event and for resuming the power supply to the tracker device after the predetermined time period (and, thus, in reaction to the detected particular event); and wherein the tracker device is configured for moving the support means by means of the actuator element to move the support means into a predetermined position in reaction to the resumed power supply. The invention is not limited to one particular sequence of interruption and resume of power supply to the tracker device and its respective control unit. Any sequence could be used which includes also the possibility to vary the time periods of interruption and/or repeat at least once the steps of interrupting and resuming power supply in order to avoid misinterpretation of for example accidentally occasioned events like for instance short electric grid power supply interruptions.

As described with respect to the inventive method provided herein, the particular position can particularly be a position in that the support means (and thereby the solar module) is oriented substantially horizontally. Again, by "substantially" horizontally, in particular, a position with an angle of the main plane of the support means (solar module) to a vertical axis that is perpendicular to an essentially horizontally oriented ground plane whereupon the tracker device is installed of between 70° to 1 10° and more particularly 80° to 100° or 85° to 95° is covered. In particular, by "substantially" horizontally a position essentially parallel (within some ± 20°, in particular, some ± 10°, more particularly, some ± 5°) to the ground whereupon the tracker device is installed is covered. The support means can be mounted on a vertical column (which may be rotatable) and in this case "substantially" horizontally covers a position wherein the support means is inclined to the vertical column within a range of angles of 70° to 1 10° and more particularly 80° to 100° or 85° to 95°.

The particular event may comprise or consist of a velocity of wind measured in the vicinity of the solar module or somewhere else that exceeds a predetermined threshold, power breakage of an electrical grid or failure of a control system controlling parts of the solar power plant, for example, some failure of the recited central communica- tion system. Usually, the solar power plant may comprise more than one solar module and tracker device. Thus, according to an embodiment the solar power plant comprises a plurality of solar modules and a plurality of tracker devices each provided with a control unit; and a plurality of sensors, in particular, comprising air speed meters, each configured to generate detection data (for example, data about a wind velocity detected by the sensors) and configured to send the detection data to the central safety system; and wherein the central safety system is configured to interrupt power supply to particular ones of the plurality of tracker devices in reaction to the detection data sent by the plurality of sensors to the central safety system. Each of the tracker devices can be equipped with its own control unit. Alternatively, a single control unit can be provided to control a particular number of the tracker devices.

If a particular event, for example, a wind speed exceeding a predetermined limit, is detected at one or more locations of the power plant, it may be sufficient to move only respective tracker devices where the excessive wind speed is measured to the par- ticular positions (safety positions) whereas the other tracker devices in other section of the power plant are kept in an operation state. In the operation state, which is different from a safety or horizontal state, the solar module on the tracker device operates by generating electric energy. The solar power plant may further comprise a central communication system (for example, in form of a SCADA system) comprising a communication line (which normally is different from the power supply to the tracker device) connecting the central communication system and at least one control unit of the tracker device and wherein the central communication system is configured to send a control signal (emergency sig- nal) to the control unit of the tracker device comprising the actuator element over the communication line in reaction to the detection of the particular event that causes the tracker device to move the support means by means of the actuator element into the predetermined position.

According to a further embodiment the solar power plant further comprises a programmable controller (like a programmable field bus system) and at least one sensor. The power supply means, the tracker device and the central safety system can communicate with each other or at least one of the others via the programmable controller (like a field bus system).

In the above examples, the central safety system may be configured to repeat the se- quence of interrupting the power supply from the power supply means to the tracker control unit for a predetermined time period and resuming the power supply to the tracker control unit after the predetermined time period and in this case the actuator element may be configured to move the support means into the predetermined position after the repetition of the sequence.

The central safety system can be adapted to the particular configuration of the solar power plant. For example, it can be connected to a backup power supply.

In all of the examples of the solar power plant according to the present invention, the solar module(s) may comprise concentrator optics as known in the art.

Additional features and advantages of the present invention will be described in the following. In the description, reference is made to the accompanying figures that are meant to illustrate examples of the invention. It is understood that such examples do not represent the full scope of the invention. Equal elements illustrated in the drawings are provided with equal reference signs. Parts of the description relating to equal elements illustrated in the different drawings may be left out.

Figure 1 illustrates a configuration of a central safety system, tracker control unit, tracker devices of solar modules and sensors of a solar power plant in accordance with an example of the present invention. Figures 2a and 2b illustrate a solar module with a tracker device and tracker control unit wherein the solar module / support means of the tracker device is shown in an operation position (Figure 2a) and a safety position (Figure 2b).

Figure 3 illustrates a configuration of a central safety system of a solar power plant in accordance with an example of the present invention.

Figure 1 shows an example of a configuration of basic elements of a solar power plant according to the present invention. Two solar modules 1 each provided with a tracker device 2 which is controlled by a respective tracker control unit 10 are schematically shown. The tracker control units 10 are connected with a power supply means 3 by power lines a. The power supply means 3 is also connected by a control line b with a central safety system 4. The power supply means 3 is schematically shown in Figure 1 , and can include a connection to the electrical grid or include a backup power sup- ply, as shown schematically in Figure 3.

The central safety system 4 detects an event with one or more sensors. For example, a wind sensor detects high wind speed at the location of the tracker device 2. In the following description of this example, it is assumed that the sensors are air speed me- ters measuring the wind velocity. Other kinds of sensors can be incorporated in the invention.

If the measured wind speed exceeds some predetermined threshold at a particular location of a section of tracker devices 2, the central safety system 4 interrupts the power supply means 3 to the tracker control units 10 of the respective tracker devices 2 for a predetermined time period and switches on power supply via power supply line a again after the predetermined time period via control line b. The interruption and resumption of power supply via the power supply line a is interpreted at the side of the tracker control unit 10 as a command to move the respective tracker device 2 with the solar module 1 (at the location of which the excessive wind speed was detected by a sensor) into a safety position, i.e., into a horizontal position in this example. An example for a solar module 1 and a tracker device 2 comprising a tracker control unit 10 and a support frame 6 is shown in more detail in Figures 2a and 2b. The solar module 1 comprises an array of solar cells and is supported on the support frame 6 comprising vertical and horizontal bars. The frame is mounted by a horizontal beam 7 to a vertical rotatable column 8 that can be driven by an actuator of the tracker device 2. The tracker device 2 comprises the rotatable column 8 that is driven by an actuator (not shown) and a tilting means 9 for appropriately tilting the support frame 6. However, the invention is not limited to this type of tracker device and can be implemented for any type of tracker device, in particular two axes trackers for concentrated photo- voltaics. Figure 2a shows the assembly in an operation state for collecting solar rays and converting solar energy in electric energy. In Figure 2b the same assembly is shown in a horizontal safety position of the solar module 1 that is adopted by means of the tilting means 9 of the tracker device 2. The tracker control unit 10 comprises an electrical panel to control the tracker device 2. Coming back to Figure 1 it is to be stated that besides the power supply lines a, in principle, no other communication means between the central safety system 4 and the tracker control unit 10 for controlling the tracker devices 2 to move the respective solar modules 1 into the safety position is needed. However, if desired, optional separate communication lines d can be provided that connect a central communication system 20 and the tracker control unit 10 with the tracker devices 2 of the solar modules 1 . The central communication system 20 and the central safety system 4 communicate via line e. The optional communication lines d and e are schematically represented in Figure 1 by dashed lines. The communication line e can be used to exchange information between the central safety system 4 and the central communication system 20. For example the central communication system 20 can report a particular event which may not be detected by the central safety system 4 itself and indicates that the tracker devices 2 have to move into the safety position.

The central safety system 4 can, on the other side, report to the central communication system what the particular status is and if a dangerous situation is present for the tracker devices 2. The central communication system 4 then can support the action to bring the tracker devices 2 into the safety position.

Both the central safety system 4 and the central communication system 20 can have their respective set of sensors in order to detect different categories of particular events, as for instance wind speed meters for the central safety system 4 in order to detect exceeding wind speeds or a sensor connected to the central communication system 20 reporting on electrical grid malfunctioning. The communication line e thus enables one to share distinct features and report complementary information to both systems, therefore reliably driving the tracker device into a safety position. However both systems can be connected to the same type of sensors in order to increase the reliability of the positioning system for very sensitive applications.

In a redundant operation mode in addition to the interruption and resumption of power supply, the central communication system 20 can send explicit commands to the tracker device 2 via the separate communication lines d in order to cause movement of solar modules 1 into the safety position, if the wind speed exceeds a predetermined limit at the location of the respective solar modules 1 . Both operations of sending explicit command signals via the communication line d and interrupting and resuming power supply to the tracker devices 2 via the power supply lines a guarantee a very high level of reliability of the safety positioning operation in case of danger or occurrence of a particular event.

Figure 3 inter alia shows a configuration of a central safety system 4 of a solar power plant in accordance with an example of the present invention in some more detail. The shown central safety system 4 is connected to the electrical grid 1 10 and the central communication system 20. The central safety system 4 comprises a programmable controller 101 for basic communication between components inside the central safety system 4 and the central communication system 20 via communication line e. The central safety system 4 further comprises at least a sensor 102, for instance a wind sensor to detect the wind speed, connected to the programmable controller 101 . Moreover, an uninterruptible power source (UPS) 103 is connected to the program- mable controller 101 for providing emergency power to the programmable controller 101 in case of a main power breakdown.

The power supply 3 shown schematically in Figure 3 comprises a connection to the electrical grid 110 which also provides an electrical connection to the central safety system 4. The power supply 3 is controlled by the programmable controller 101 . Additionally, a backup power supply 104, for example, a battery, provides emergency power to the tracker control units, allowing to move the tracker devices with the solar modules into the safety position (for example, horizontal position) in case of a main power breakdown, controlled by the programmable controller 101 . The power supply 3 provides the emergency power from the backup power supply 104 or the power from the electrical grid to the tracker device 2 and the tracker control unit 10 via power lines a via the switch gear 106 comprised in the power supply 3 and controlled by the programmable controller 101 via control line h. The programmable controller 101 controls via a switch gear 106 the power supply of tracker control units of respective tracker devices (interruption and resumption as described with reference to Figure 1 ). The central communication system 20 allows for communication to the tracker control units of tracker devices via communication lines d and communication means 109 provided in addition to the power supply lines a as also described with reference to Figure 1 . The central communication system 20 is connected by data lines with at least a sensor 102', for instance a wind sensor, in order to communicate particular events (for example, excessive wind velocities detected by the wind sensor 102') to the central communication system via the communication line e as already explained above. Such a sensor 102' can be different to the sensor 102 comprised in the central safety system 4, but is not limited to it, and is shown schematically in Figure 3. The dashed line Ho sensor 102 represents the possibility to use the same set of sensors for the central safety system 4 and the central communication system 20. Then switch gear 106 is used to distribute the power to the tracker control units, as commanded by the programmable controller 101 via control line b due to the detection of a particular event. The central communication system 20 and the communication means 109 are used to connect all devices (including the tracker control unit) to a communication network. In standard solar power plants, Ethernet cables and, depending on the size of the CPV Power Plant, also fibre optic cables can be used to realize the communication. However the invention is not limited to these types of realized communication.

The shown central safety system 4 gets information from sensors, like the wind sensor 102, and from other central components, like the power supply 3, the backup power supply 104, the UPS of the programmable controller 103 and from the central communication system 20. Theses central components may also send status events to the programmable controller 101 like an error message coming from the backup power supply 104 indicating that it has not enough energy to bring the tracker devices into the safety position in case of another upcoming event, like a main power breakdown. Based on this information the programmable controller 101 can decide to take the tracker device 2 as a precaution into the safety position and inform the central com- munication system over the communication line e about the particular event. These kinds of status events can be sent from all central components to the programmable controller 101 .

Based on these information the programmable controller 101 steers the different ele- ments like the switch gear 106 of the power supply 3 or, in a particular case, the backup power supply 104 to control the power supply 108 of the tracker control units 10 which is schematically shown in Figure 3 (interruption and resumption of the power supply to the tracker control unit). All previously discussed examples are not intended as limitations but serve as examples illustrating features and advantages of the invention. It is to be understood that some or all of the above described features can also be combined in different ways.

Claims

1 . Method for controlling a tracker device of a solar module of a solar power plant, wherein the solar power plant comprises a central safety system and wherein the tracker device comprises a control unit, an actuator element and a support means for supporting the solar module, comprising the steps of detecting a particular event; interrupting for a predetermined time period power supply to the control unit of the tracker device in reaction to the detection of the particular event; resuming power supply after the predetermined time period; and in reaction to the resumed power supply actuating the support means by the actuator element to move the support means into a predetermined position.

2. The method according to claim 1 , wherein the predetermined position of the support means is a substantially horizontal safety position. 3. The method according to claim 1 or 2, wherein the particular event comprises a measured wind velocity exceeding a predetermined threshold.

4. The method according to claim 1 or 2, wherein the particular event comprises error messages of other components, in particular the power supply, the backup power supply, or the UPS of the programmable controller.

5. The method according to claim 1 , wherein the predetermined position of the support means is a substantially vertical safety position. 6. The method according to one of the preceding claims, wherein the step of detecting the particular event is performed by means of one or more sensors, in particular, comprising air speed meters, of the solar power plant. The method according to one of the preceding claims, further comprising sending a control signal, in particular, an emergency signal, to the control unit of the tracker device over a communication system comprising a communication line in reaction to the detection of the particular event, wherein the control signal causes the tracker device to move the support means into the predetermined position.

The method according to one of the preceding claims, comprising repeating the sequence of interrupting power supply to the tracker device for a predetermined time period and resuming power supply after the predetermined time period and wherein the support means is actuated by the actuator element to move it into the predetermined position after the repetition of the sequence.

The method according to one of the preceding claims, further comprising activating a backup-power supply for supplying power to the tracker device in reaction to the detection of the particular event or in reaction to a detected different event.

Solar power plant, comprising at least one solar module mounted on a support means; a tracker device configured for moving the support means by means of an actuator element and comprising a tracker control unit configured to control the tracker device; a power supply means configured for supplying power to the tracker device; at least one sensor configured for detecting a particular event; a central safety system configured for interrupting the power supply from the power supply means to the control unit of the tracker device for a predeter- mined time period in reaction to the detection of the particular event and for resuming the power supply to the tracker device after the predetermined time period; and wherein the tracker device is configured for moving the support means by means of the actuator element to move the support means into a predetermined position in reaction to the resumed power supply.

The solar power plant according to claim 10, comprising a plurality of solar modules and a plurality of tracker devices each equipped with a control unit; and a plurality of sensors, in particular, comprising air speed meters, each configured to generate detection data and send the detection data to the central safety system; and wherein the central safety system is configured to interrupt power supply to particular ones of the control units of the plurality of the tracker devices in reaction to the detection data sent by the plurality of sensors to the central safety system.

12. The solar power plant according to claim 10 or 1 1 , wherein the predetermined position of the support means is a substantially horizontal safety position.

13. The solar power plant according to one of the claims 10 to 12, wherein the par- ticular event comprises a measured wind velocity exceeding a predetermined threshold.

14. The solar power plant according to one of the claim 10 or 1 1 , wherein the predetermined position of the support means is a substantially vertical safety posi- tion.

15. The solar power plant according to one of the claims 10 to 14, further comprising a central communication system comprising a communication line connecting the central communication system and at least one solar module and wherein the central communication system is configured to send a control signal to the tracker device of the at least one solar module over the communica- tion line in reaction to the detection of the particular event that causes the tracker device to move the support means by means of the actuator element into the predetermined position.

The solar power plant according to one of the claims 10 to 15, further comprising a programmable controller and wherein the at least one sensor, the power supply means, the tracker device and the central safety system can communicate with each other or at least one of the others via the programmable controller. 17. The solar power plant according to one of the claims 10 to 15, wherein the central safety system is configured to repeat the sequence of interrupting the power supply from the power supply means to the tracker device for a predetermined time period and resuming the power supply to the control unit of the tracker device after the predetermined time period and wherein the tracker de- vice is configured to move the support means into the predetermined position after the repetition of the sequence.

18. The solar power plant according to one of the claims 10 to 17, wherein the at least one solar module comprises concentrator optics.