Method and system for controlling a tracker for a solar power plant

Abstract

A method and system for controlling a tracker (5) for a solar power plant (200). The method comprises: checking, with a controller (2), that the PV panel (4) associated with the tracker (5) is stationary; at a first instant (t1), measuring a first temperature value (T1) with a temperature sensor (1a) and a first set of accelerations (α1) of the PV panel (4) with an accelerometer (1b); at a second instant (t2), measuring a second temperature value (T2) and a second set of accelerations (α1); calculating a correction function based on the acceleration (α1, α2) and temperature (T1, T2) values; at a third instant (t3), actuating a motor (3) to bring the PV panel (4) to a target position; measuring a third temperature value (T3) and a third set of accelerations (α3); calculating a set of modified accelerations (α'3) using the correction function and the third temperature value (T3) and checking whether the set of modified accelerations (α'3) corresponds to the target position for the PV panel (4).

Description

[0001] DESCRIPTION

[0002] QUALIFICATION

[0003] METHOD AND SYSTEM FOR CONTROLLING A TRACKER FOR A SOLAR PLANT

[0004] FIELD OF INVENTION

[0005] The present invention pertains to the field of renewable energy. In particular, it relates to a method and system for improving the accuracy of a tracker responsible for positioning one or more photovoltaic panels in a desired position. The invention is applicable to the production of energy from a solar plant with photovoltaic panels equipped with sun tracking.

[0006] BACKGROUND OF THE INVENTION

[0007] To better utilize solar radiation, the photovoltaic (PV) panels in many solar plants are moved to point toward the sun so that solar radiation adequately falls on the PV panels. Trackers are used to accomplish this task. A tracker includes structural, electromechanical (e.g., a motor), and electronic (e.g., sensors, controller) elements to track the PV panel, usually toward the sun.

[0008] Trackers can be of different types; for example, a two-axis (or degree-of-freedom) tracker allows for pitch (inclination angle along the East-West axis) and roll (inclination angle along the North-South axis) guidance. There are also trackers that move relative to a single axis with a tilt angle. In both cases, accelerometers are commonly used as sensors to measure the appropriate orientation. Accelerometers measure the Earth's gravitational acceleration vector by projecting it onto a Cartesian orthogonal coordinate system. These accelerometers are sometimes combined with gyroscopes and incorporated into inertial measurement units (IMUs). Through mathematical transformations, the acceleration components are converted into angles in the coordinate system.

[0009] The technology known as MEMS (Micro Electromechanical Systems) is the most widely used technique for manufacturing accelerometers (as individual elements or as components of an IMU). Given the nature of their manufacturing process, sensors manufactured with MEMS provide measurements that tend to experience temperature drift. This drift with temperature is specific to each accelerometer. This makes it uneconomical to characterize the specific drift of each accelerometer produced on a cost-minimizing, mass-produced scale.

[0010] As a result of inaccurate acceleration measurements, the sun is not tracked properly, thus the captured irradiance decreases and with it the energy efficiency of the PV panel or panels associated with said accelerometer, causing a decrease in the electrical production of the solar plant.

[0011] On the other hand, solar trackers sometimes need to adopt certain fixed positions. For example, they are placed in a safe position under high wind speed conditions. This safe position is often referred to as the guard position. The more precise the acceleration measurements are to determine the PV panel's tilt angle relative to an axis, the more accurate the guard positioning will be, ensuring safer operation of the photovoltaic plant.

[0012] DESCRIPTION OF THE INVENTION

[0013] In view of the above situation, more precise and customized solar tracking would be desirable to allow for better utilization of solar irradiance. For solar plants located in areas with large temperature fluctuations, such as desert or semi-desert regions, this behavior can cause significant reductions in electrical energy. It is also useful for allowing the PV panel to adopt specific positions with greater precision for safety or maintenance reasons.

[0014] The present invention provides a method and system according to claims 1 and 8 for addressing the aforementioned situation. Various advantageous embodiments are defined in the dependent claims. The method is implementable as software with encoded instructions stored on a digital storage medium readable and executable by a processing means. To control a tracker in a solar plant, according to the proposed method, several executable steps are included in a controller. The controller checks that the PV panel (or panels) associated with the tracker is stationary and initially measures a first ambient temperature value with a temperature sensor and a first set of accelerations with an accelerometer. The accelerations measured with the accelerometer can be converted to an angle of inclination with respect to a reference axis, or to several angles of inclination with respect to various axes.For example, typically two in the case of a dual-axis tracker: one inclination angle for pitch and / or another for roll. Alignment with respect to one or both of the tracker's axes determines the position of the PV panel.

[0015] According to the proposed method, a second ambient temperature value and a second set of accelerations associated with a position (determined by one or more tilt angles) of the PV panel are measured at a later time. A correction function is then calculated to be applied to the next measurements taken by the accelerometer. This correction function takes into account the difference between the acceleration and temperature values ​​measured at both times. With the PV panel stationary, differences in the measurements taken by the accelerometer are due to temperature drift.

[0016] When a motion instruction is issued to move the PV panel from its current position to another target position, the controller actuates a motor responsible for moving the PV panel. The controller checks whether the target position of the PV panel is reached using the correction function. To do this, a third set of accelerations associated with the PV panel and a third temperature value are measured. The correction function is applied, resulting in a set of modified accelerations that mitigate thermal drift. The modified accelerations are converted into one or two modified tilt angles. A check is made to see if the modified angle corresponds to the target position for the PV panel, as set by one or more tilt angles. If not, the motor is actuated until the target position is reached within a configurable desired error margin.If the motor is stepper, the follower approaches the target position through sequential movements.

[0017] Similarly, a system for controlling a tracker for a solar plant is proposed. To this end, the system includes several devices, including a controller, a temperature sensor, and an accelerometer associated with a tracker. The controller is responsible for controlling a motor mechanically coupled to the PV panel. In turn, said tracker can be associated with a single PV panel or with several, for example, arranged in a row. The controller manages various operations and instructions in the system to carry out the steps mentioned in the previous method. In the case of a single-axis tracker, the controller drives a motor that moves the PV panel to a target position set by a given tilt angle with respect to the tracker's axis of movement.

[0018] A controller is understood to be an electronic component capable of executing programs, processing data and instructions (actuation, reading, etc.) to manage other devices present in the tracker such as motor(s) or sensor(s).

[0019] In one aspect of the invention, calibration is performed by taking accelerometer readings at times when the PV panel is not moving. In this document, the "Idle state" of a tracker refers to a state in which the tracker is not moving, i.e., there is no activity on the motor(s) and the PV panel remains stationary. On the other hand, the tracker is considered to be in an "Active state" when it is moving or ready to move.

[0020] For example, among other possible situations, the tracker is in the Standby state in the following situations: during the night period, during a maintenance stop, when they are in a defensive position, or in the interval between two consecutive movements for solar tracking.

[0021] Each time a standby state is reached, measurements of each accelerometer axis and temperature are stored to characterize its drift with temperature. Any variations in the accelerometer readings can be assumed to be due solely to the influence of temperature since the PV panel is not moving. Once the drift is known, a correction can be calculated to apply to the measurements taken with the accelerometer. Additionally, a check can be scheduled periodically to verify that the correction is still valid.

[0022] With the corrected accelerometer measurements, a controller can control the motor responsible for moving the PV panel to steer it appropriately to a more precise position. Typically, this position is indicated as a tilt value relative to an axis set by a central computer managing the solar plant. However, in other embodiments, the controller could be responsible for producing the target positions autonomously, for example, using information from additional sensors.

[0023] BRIEF DESCRIPTION OF THE FIGURES

[0024] Embodiments of the present invention are presented, by way of example and illustrative purposes only, in the accompanying drawings in which like elements are numbered alike.

[0025] FIG. 1: Schematic block diagram of a solar plant.

[0026] FIG. 2: Flowchart of stages and operations.

[0027] FIG. 3: Schematic block diagram of the system.

[0028] FIG. 4: Thermal drift of commercial accelerometer vapors with a fixed inclination of 30°.

[0029] FIG. 5: Example of thermal drift for an accelerometer with and without calibration.

[0030] Numerical references

[0031] 1a Temperature sensor.

[0032] 1 b Accelerometer.

[0033] 2 Controller.

[0034] 3 Engine.

[0035] 4 PV Panels.

[0036] 5 Followers.

[0037] 7 Mainframe.

[0038] 20th Active State.

[0039] 20b State of Rest.

[0040] 21 Follower movement step.

[0041] 22 Follower end-of-movement step.

[0042] 23 Initial tracker measurements step.

[0043] 24 Follower wait step.

[0044] 25 Step of subsequent measurements of the follower.

[0045] 26 Step acceleration comparison.

[0046] 27 Accelerometer calibration step. 28 Accelerometer correction step.

[0047] 100 System.

[0048] 200 Solar plant.

[0049] DESCRIPTION OF IMPLEMENTATION MODES

[0050] With reference to the above figures, without limitation, various embodiments of the invention are described for better understanding.

[0051] FIG. 1 shows a schematic functional block diagram for a solar plant 200 where there are multiple PV panels 4. Typically, each PV panel 4 has its corresponding tracker 5 and associated sensors, such as an accelerometer (or an IMU) and a temperature sensor (not shown in this figure). Associated with the tracker 5 is a motor 3 and a controller 2. The motor 3 is locally controlled by the controller 3. According to one embodiment of the invention, the system 100 for calibrating a solar tracker incorporates the controller 2 itself. The motor is generally a stepper motor.

[0052] The position of the sun is calculated using a central computer 7. Generally, an astronomical algorithm is used with geographic information from solar plant 200 and temporal information such as calendar time and date data to determine the movement of the sun's position at a given time.

[0053] The central computer 7 communicates with the controllers 2 of the trackers 5 and sends instructions to them so that said controllers 2 direct the motors 3 under their control and move the PV panels 4, mainly to adopt an inclination that points in the direction of the sun. This allows, for example, the PV panels 4 to theoretically follow the position of the sun. Additionally, in other situations, the central computer 7 takes meteorological measurements and determines whether the trackers 5 should follow the sun or move to a different position to take advantage of diffuse radiation or to protect the solar plant, for example, by triggering alarms for wind, snow, hail, etc.

[0054] Typically, each controller 2 accesses local information provided by the sensors associated with its PV panel 4, specifically, an accelerometer that provides acceleration measurements. Controller 2 uses these acceleration measurements to obtain a measurement of the PV panel 4's inclination relative to a reference axis. Controller 2 can therefore calculate how PV panel 4 should be moved using motor 3 to comply with the instructions received from central computer 7. In other situations, controller 2 itself may be programmed to autonomously determine how PV panel 4 should be moved, for example, in the event of a loss of communication with central computer 7.

[0055] In practice, due to the temperature drift error in the accelerometer measurements, the actual position of the PV panel is inaccurate. Controller 2 controls motor 3 based on these measurements, resulting in performance losses among other disadvantages. To avoid these, a system 100 is designed to calibrate a solar tracker that performs various tasks. System 100 uses temperature measurements from a temperature sensor and is responsible for correcting the measurement provided by the accelerometers so that controller 2 applies the correct motion to motor 3, regardless of whether each accelerometer varies with temperature.

[0056] It should be noted that accelerometers allow the acceleration of gravity vector to be broken down into its components referenced to a local Cartesian basis. This basis usually consists of two axes (XY) or three axes (XYZ). From these accelerations (a¡), the inclination measurement (pitch angle p and roll angle r) can be derived by applying trigonometric operations, following the following conversion ratio:

[0057] Note that equations Eq. 1 and Eq. 2 are strongly nonlinear. Instead, a linear calibration is proposed. The calibration is performed on acceleration measurements, not on pitch and roll values.

[0058] It is worth noting that the number of acceleration axes required must always be greater than the number of degrees of freedom to be measured. Thus, for a single-axis solar tracker, a two-axis Cartesian accelerometer is sufficient. Similarly, a two-axis solar tracker requires a three-axis accelerometer. System 100 is valid for both.

[0059] FIG. 2 shows a flowchart of an operating cycle according to the method for controlling a solar tracker for one or more PV panels. The diagram shows different steps performed in the solar tracker controller, connected by arrows. The dashed lines indicate a relationship between data and a step, for example, data obtained from measurements or calculations.

[0060] The tracker starts with the Active state 20a, that is, in an operating mode in which the tracker is ready to begin moving or is already moving. In a tracker movement step 21, the controller directs the PV panel via the motor to advance it to a target position (also known as the set position). This is usually because a central computer sends a movement instruction to the controller.

[0061] In a step 22 of end of movement of the follower, the controller determines that the panel has reached its objective position, ends the movement and remains in a state of Idle 20b until it receives a new instruction to move that would take it to step 21 and keep it in Active state.

[0062] Once in Resting State 20b, follow steps 23-28.

[0063] In a step 23 of initial measurements in the tracker, the controller reads and stores the measurement of the temperature sensor (Ti) and acceleration of all axes of the accelerometer (a¡i) of the tracker.

[0064] In a follower wait step 24, the controller waits for a configurable time interval.

[0065] In a subsequent measurement step 25 of the tracker, the controller reads the measurement from the temperature sensor (T2) and the accelerometer (a¡2); it also calculates the difference with the initial measurement values ​​stored in step 23. In a comparison step 26, the temperature difference is compared with a temperature threshold. The difference in accelerations is also compared with a deviation threshold. If none of these thresholds are exceeded, then the controller returns to the wait step 24. These thresholds are configurable.

[0066] If, on the other hand, one of the thresholds is exceeded, the tracker accelerometer is calibrated (or recalibrated) in step 27. The controller then calculates the drift gain for each axis (A¡) based on the current temperature (T2) and the temperature stored in step 23 (Ti). To perform this calculation, controller 2 collects the current acceleration measurements (a¡2) and solves the following equation for each acceleration axis:

[0067] In a step 28 of obtaining the correction of the accelerometer (a'¡) of the tracker, a correction function is obtained and the Active state 20a is returned to. Thus, from now on, all accelerations measured by the accelerometer are corrected with the correction function that uses the corresponding drift gain (A¡), the reference temperature (Ti) and the instantaneous temperature reading (T) before computing the inclination: a (T) = at - (T - Tj) • A¡ [fe. 4]

[0068] When step 21 of the tracker movement is performed, the controller already has the correction function. The controller determines that the panel has reached its target position and terminates the movement as indicated in step 22 by applying the linearly corrected accelerations (a'¡). In this way, it checks whether the inclination after the applied movement is as ordered by the central computer, minimizing temperature errors in the accelerometer.

[0069] If an instruction to move the tracker is received at any of steps 21-27, the Idle state 20b is then exited, the stored values ​​(Ti, a¡i) of the initial measurements are discarded and the Active state 20a and step 21 are returned to, starting a new cycle in the method for controlling the solar tracker.

[0070] FIG. 3 is a schematic block diagram of system 100 that applies the method of FIG. 2 to a single-axis tracker 5. The diagram can be seen to follow a closed-loop scheme. A PV panel 4 can be seen being moved by a motor 3 according to instructions from a controller 2 in the Active state. Controller 2 accesses measurements (T, a) taken by a temperature sensor 1a and an accelerometer 1b, respectively. It also receives instructions from the central computer 7 of the solar plant regarding the position to be adopted by the PV panel 4, for example, a night position corresponding to an angle of inclination with respect to an axis. By means of the motor 3 in charge, controller 2 moves and orients the PV panel 4. It then remains in the Idle state.

[0071] As explained in FIG. 2, if the accelerometer 1 b is calibrated, the controller 2 can apply a correction (a') to the accelerometer measurement (cr) to properly control the motor 3, so that a particular position is adopted and / or the sun is tracked more accurately.

[0072] The tilt applied to the PV panel 4 is individual and corrects, or at least mitigates, the reading error due to the temperature dependence of its accelerometer 1b.

[0073] The thermal drift constant A¡ of a particular accelerometer 1b is usually valid for quite some time. However, it occasionally needs to be recharacterized. Among other factors, aging or exposure to weathering of the accelerometer 1b makes it advisable to recalibrate it periodically. Establishing thresholds and ensuring they are not exceeded ensures the calibration's continued validity.

[0074] It is advantageous to calibrate or recalibrate a tracker during the nighttime period. The tracker is in the Standby state, and the PV array 4 maintains its position at night with a known, fixed inclination. During this period, the motor 3 remains stopped. At certain intervals, the controller 2 monitors the acceleration measured by the accelerometer 1b corresponding to the fixed inclination, and variations due solely to temperature are observed to calculate the drift gain according to Eq. 3. With this value, the correction function to be applied is updated according to Eq. 4.

[0075] For simplicity, the case of a single-axis tracker has been described. In the case of two axes, the procedure would be the same. There would simply be a movement instruction to a target position issued by the central computer 7, which would include two pieces of data for orienting the PV panel 4: a tilt angle for pitch and a tilt angle for roll. Controller 2 would employ two correction functions, one for each axis. Controller 2 would control motor 3 (or motors) to move the PV panel 4 until the measurement from the accelerometer 1b, after correction applied by controller 2, reaches the target position according to the pitch and roll angles indicated by the central computer 7 (or a value that remains within a certain margin of error).

[0076] FIG. 4 shows experimentally the effects of thermal drift on the reading of two commercial accelerometers for a real tracker tilt of 30°.

[0077] The x-axis represents time in seconds. The test lasts approximately 22 hours (1341 s). The y-axis represents two different magnitudes. The inclinations obtained according to AC1 and AC2 readings correspond to units of sexagesimal degree (°) along the Y1 axis on the left. The "T_amb" graph is the reading from a sensor for ambient temperature; the y-axis values ​​represent degrees Celsius (°C) along the Y2 axis on the right. T_amb shows the progression of ambient temperature during the experiment, which reaches a rise of approximately 9°C.

[0078] Graphs AC1 and AC2 show the evolution with temperature of the inclinations obtained from measurements of the first commercial accelerometer and the second commercial accelerometer, using both initially, 0 is obtained o but it is observed that the readings fluctuate quite a bit. The value 0 orelative to the reference axis for both accelerometers corresponds to an actual tracker inclination of 30° relative to the horizontal. In the absence of thermal drift, the inclination obtained from readings from both accelerometers should remain constant; however, this is not the case.

[0079] Experimental tests suggest that with temperature variations of 10 °C, the measurements provided by some accelerometers, such as the second accelerometer, in the AC2 graph, translate into an error in inclination of 0.5° to 1°. o , approximately. Thermal fluctuations of more than 10°C are common during the daily operation of a solar plant.

[0080] FIG. 5 shows a graph with several curves to illustrate the thermal drift of two different accelerometers: “AC1” and “AC2”. On the X axis, several hours of the day (including the night period) are represented. On the Y1 axis, on the left, the angle for a PV panel is represented in sexagesimal degrees (from -1 o a +1°) above the horizontal plane. Referred to this ordinate axis Y1, the inclinations obtained with measurements from the accelerometer AC1 and the accelerometer AC2 before calibration (curves #1nc, #2nc) and once calibrated and applying their corresponding correction function (curves #1c, #2c) can be read in a period between a little before 18 h (ti) and 2 h (f2) in which the PV panel remained motionless.

[0081] On the right, the measured ambient temperature is represented on the Y2 axis. It can be seen that, between time points t1 and t2, the temperature dropped 10°C, from 27°C at t1 to 17°C at t2. During this time, the panel remained stationary for the test. In contrast, with the AC1 accelerometer, the calculated inclination value was variable, decreasing with decreasing temperature. It can be seen that both curves have a negative average slope; slightly in curve #1nc, quite marked in curve #2nc.

[0082] By applying calibration and a correction function as proposed in this document, this undesired behavior is corrected at t2. As noted, the calibrated curves experience a "jump" compared to the uncalibrated ones. For curve #1 nc, the correction applied thanks to calibration is not very large, whereas for curve #2nc the magnitude of the jump is approximately 20 hundredths of a sexagesimal degree, that is, 0.20° when the temperature varies by 10°C. In desert areas, it is common for accelerometers to operate daily within a temperature range that varies by 20°C and even 30°C. Assuming a linear response with temperature, an incorrect aiming of 0.5° sometimes generates considerable performance losses.

[0083] The above also serves as an example of the disparity in temperature response between two different sensors, which makes it difficult to establish a generalized correction.

[0084] The present invention is not limited to the particular embodiments described above, but the invention shall include all embodiments that fall within the scope of the appended claims.

Claims

CLAIMS 1. Method for controlling a tracker (5) for a solar plant (200), comprising the following steps: - check, with a controller (2), that the PV panel (4) associated with the tracker (5) is stationary, in an initial position; - measuring, at a first time (t1), a first temperature value (T1) with a temperature sensor (1a) and a first set of accelerations (a1) of the PV panel (4) with an accelerometer (1b); - measuring, at a second moment (t2) separated by a time interval from the first moment (t1), a second temperature value (T2) with the temperature sensor (1a) and a second set of accelerations (a2) of the PV panel (4) with the accelerometer (1b); - calculate a correction function from the measured values ​​of acceleration (a1 , a2) and temperature (T 1 , T2) at the first moment (t1) and the second moment (t2); - actuating, with the controller (2), a motor (3) to bring the PV panel (4) to a target position; - measuring, at a third time (t3), a third temperature value (T3) with the temperature sensor (1a) and measuring a third set of accelerations (a3) ​​of the PV panel (4) with the accelerometer (1b); - obtain a set of modified accelerations (a'3) from the third set of accelerations (a3) ​​using the correction function and the third temperature value (T3); - check, with the controller (2), whether the set of modified accelerations (a'3) corresponds to a position of the PV panel (4) that is within a threshold with respect to the target position for the PV panel (4).

2. Method for controlling a tracker (5) according to claim 1, further comprising: - checking, with the controller (2), whether the difference between the first temperature value (T1) or second temperature value (T2) and the third temperature value (T3) exceeds a threshold; - recalculate, if so, the correction function from the measured values ​​of acceleration (a2, a3) and temperature (T2, T3) at the second moment (t2) and the third moment (t3).

3. Method for controlling a tracker (5) according to claim 1 or 2, further comprising: - check, with the controller (2), if in the third set of accelerations, there is a value with a difference from the first set or the second set and the difference exceeds a threshold; - recalculate, if so, the correction function from the measured values ​​of acceleration (a2, a3) and temperature (T2, T3) at the second moment (t2) and the third moment (t3).

4. Method for controlling a tracker (5) according to any one of the preceding claims 1 to 3, wherein the method comprises the step of driving the motor (3) with the controller (2), if the position of the PV panel (4) is not within a threshold with respect to the target position; 5. Method for controlling a follower (5) according to claim 4, wherein the motor (3) is step-by-step with predetermined movements and is driven by the controller (2) incrementally by applying a number of predetermined movements.

6. Method for controlling a tracker (5) according to any one of the preceding claims 1 to 5, wherein the controller (2) drives the motor (3) according to a movement instruction received from a central computer (7).

7. Method for controlling a tracker (5) according to any one of the preceding claims 1 to 6, wherein the initial position is a fixed position of the following: a night position, a maintenance position, a defense position, or a position between two consecutive solar tracking movements.

8. System (100) for controlling a tracker (5) for a solar plant (200), comprising: a temperature sensor (1a) configured to measure an ambient temperature value; an accelerometer (1b) configured to measure an angle value of the PV panel (4); a controller (2) configured to: check that the PV panel (4) associated with the tracker (5) is stationary, in an initial position; measure, at a first time (t1), a first temperature value (T1) with the temperature sensor (1a) and a first set of accelerations (a1) of the PV panel (4) with the accelerometer (1b); measuring, at a second time (t2) separated by a time interval from the first time (t1), a second temperature value (T2) with the temperature sensor (1a) and a second set of accelerations (a2) of the PV panel (4) with the accelerometer (1b); calculating a correction function from the measured acceleration (a1, a2) and temperature (T1, T2) values ​​at the first time (t1) and the second time (t2); driving a motor (3) to bring the PV panel (4) to a target position; measuring, at a third time (t3), a third temperature value (T3) with the temperature sensor (1a) and measuring a third set of accelerations (a3) ​​of the PV panel (4) with the accelerometer (1b); obtaining a set of modified accelerations (a'3) a third set of accelerations (a3) ​​by means of the correction function and the third temperature value (T3);checking whether the set of modified accelerations (a'3) corresponds to a position of the PV panel (4) that is within a threshold with respect to the target position for the PV panel (4); 9. System (100) for controlling a tracker (5) according to claim 8, wherein the controller (2) is further configured to: - check whether the difference between the first temperature value (T1) or second temperature value (T2) and the third temperature value (T3) exceeds a threshold; - recalculate, if so, the correction function from the measured values ​​of acceleration (a2, a3) and temperature (T2, T3) at the second moment (t2) and the third moment (t3).

10. System (100) for controlling a tracker (5) according to claim 8 or 9, wherein the controller (2) is further configured to: - check if in the third set of accelerations, there is a value with a difference from the first set or the second set and the difference exceeds a threshold; - recalculate, if so, the correction function from the measured values ​​of acceleration (a2, a3) and temperature (T2, T3) at the second moment (t2) and the third moment (t3).

11. System (100) for controlling a tracker (5) according to any one of the preceding claims 8 to 10, wherein the controller (2) actuates the motor (3) if the position of the PV panel (4) is not within a threshold with respect to the target position.

12. System (100) for controlling a tracker (5) according to claim 11, wherein the motor (3) is step-by-step with predetermined movements and where the controller (2) drives the motor (3) incrementally by applying a number of predetermined movements.

13. System (100) for controlling a tracker (5) according to any one of the preceding claims 8 to 12, wherein the controller (2) is configured to receive a movement instruction from a central computer (7) and drive the motor (3) according to said instruction.

14. System (100) for controlling a tracker (5) according to any one of the preceding claims 8 to 13, wherein the initial position is a fixed position of the following: a night position, a maintenance position, a defense position, or a position between two consecutive solar tracking movements.

15. A computer program product that includes code executable by a processor, which when executed, carries out the method of claims 1 to 7.

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