Patent Description:
Solar trackers orient photovoltaic solar panels towards the sun in order to track the sun's trajectory throughout the day and maximize energy capture. Generally, the efficiency of photovoltaic solar panels is maximized when they receive solar radiation perpendicular to the surface of the panels.

Horizontal solar trackers rotate the photovoltaic solar panels about an axis of rotation which is substantially horizontal with respect to the ground. The axis of rotation is aligned in the north-south direction and rotates in the east-west direction for solar radiation to strike as perpendicular as possible to the surface of the photovoltaic solar panels throughout the day. In high-capacity solar plants, horizontal solar trackers have several axes and are arranged in several rows of photovoltaic solar panels, with one axis per row.

Horizontal solar trackers comprise a plurality of posts extending and separated longitudinally along an axis and a support structure which is supported on the plurality of posts. The support structure comprises a main crossbar extending along the axis and a plurality of transverse crossbars oriented orthogonally to the main crossbar. A plurality of photovoltaic solar panels is arranged on the support structure and a rotation is applied to the main crossbar to move the photovoltaic solar panels and orient same towards the sun by means of an electric motor which is operatively coupled to the main crossbar.

There are different mechanical solutions to cause the rotational movement of the main crossbar, seeking to maximize the total number of photovoltaic solar panels that are moved with a single electric motor at all times. This is usually achieved with complex mechanical systems which allow movement to be transmitted from a single motor. For example, <CIT> shows a solar tracker with several rows of photovoltaic solar panels which uses transverse coupling rods to transmit the movement of an electric motor to all the main crossbars of the solar tracker. <CIT> shows a solar tracker with several linear actuators distributed along the axis of the solar tracker to apply a rotation on the main crossbar, and the movement of an electric motor is transmitted to the linear actuators by means of longitudinal coupling systems.

<CIT> shows a solar tracker comprising a plurality of photovoltaic solar panels with a first set of panels and a second set of panels, a plurality of posts extending and separated longitudinally along an axis, a support structure which is supported on the plurality of posts, the support structure comprises a main crossbar extending along the axis and a plurality of transverse crossbars oriented orthogonally to the main crossbar, the plurality of photovoltaic solar panels is arranged on the support structure, a first electric motor which is operatively coupled to a first part of the main crossbar to apply a rotation to the first part of the main crossbar and move the first set of panels to a final angular position, and a second electric motor which is operatively coupled to a second part of the main crossbar, spaced from the first part, to apply a rotation to the second part of the main crossbar and move the second set of panels to the final angular position. In that sense, document <CIT> shows a solar tracker with several electric motors distributed along the main crossbar of the solar tracker. The electric motors are controlled by means of a single central controller and attached by means of a power line which applies a voltage to all the electric motors at the same time so that they can act simultaneously.

<CIT> shows a solar tracker for capturing solar radiation comprising a support, a rotating shaft, and solar panels. The solar tracker also comprises a tracking system capable of operating the rotating shaft for optimal placement of the solar panel and a blocking system connected to the rotating shaft.

The object of the invention is to provide a solar tracker and a control method of the solar tracker, as defined in the claims.

An aspect of the invention relates to a solar tracker comprising a plurality of photovoltaic solar panels with a first set of panels and a second set of panels; a plurality of posts extending and separated longitudinally along an axis; a support structure which is supported on the plurality of posts, the support structure comprises a main crossbar extending along the axis and a plurality of transverse crossbars oriented orthogonally to the main crossbar, the plurality of photovoltaic solar panels is arranged on the support structure; a first electric motor which is operatively coupled to a first part of the main crossbar to apply a rotation to the first part of the main crossbar and move the first set of panels to a final angular position; a second electric motor which is operatively coupled to a second part of the main crossbar, spaced from the first part, to apply a rotation to the second part of the main crossbar and move the second set of panels to the final angular position; a first position sensor for determining an initial angular position of the first set of panels; a first controller configured to control the first electric motor and move the first set of panels to the final angular position depending on the initial angular position determined by the first position sensor; a second position sensor for determining an initial angular position of the second set of panels; and a second controller configured to control the second electric motor and move the second set of panels to the final angular position depending on the initial angular position determined by the second position sensor.

Another aspect of the invention relates to a control method of the solar tracker defined above, which comprises:.

A solar tracker having a controller for each electric motor, which allows each electric motor to act independently on its respective set of panels, is thereby obtained. Furthermore, each controller has information about the angular position to which the set of panels must be moved, whereby the angular position of each set of panels can be corrected in the event that the sets of panels are misaligned with respect to one another. This independent control of the panels cannot be achieved in systems using a single motor which move all the photovoltaic solar panels at the same time by means of mechanical systems (<CIT>, <CIT>), or in solar trackers using a single controller to move several electric motors which act on the photovoltaic panels at the same time (<CIT>).

Furthermore, having information about the angular position of each set of panels separately allows the galloping effect to be detected. Said effect is an aeroelastic instability caused by wind which generates large-amplitude oscillations in the support structures of solar trackers, causing a movement that may end with the structure collapsing. By knowing the angular position of each set of panels and being able to move said panels independently, the sets of panels can be moved to angular positions in which said effect is reduced or cancelled.

These and other advantages and features of the invention will become apparent in view of the figures and detailed description of the invention.

The invention relates to a solar tracker comprising a plurality of photovoltaic solar panels <NUM>.

The plurality of photovoltaic solar panels <NUM> has at least a first set of panels <NUM> and a second set of panels <NUM>. A first electric motor <NUM> is operatively coupled to the first set of panels <NUM> to move the first set of panels <NUM> to a final angular position and a second electric motor <NUM> is operatively coupled to the second set of panels <NUM> to move the second set of panels <NUM> to the final angular position.

The angular position of a set of panels is the angle defined between the horizontal of the ground and the surface of the photovoltaic solar panels <NUM> of the set of panels.

The final angular position may be the angular position of the photovoltaic solar panels <NUM> in which the conversion of solar radiation into electric power is maximized. For example, the final angular position is a position in which the surface of the photovoltaic solar panels <NUM> is comprised in a plane substantially perpendicular to solar radiation.

The solar tracker comprises a first position sensor <NUM> for determining an initial angular position of the first set of panels <NUM> and a second position sensor <NUM> for determining an initial angular position of the second set of panels <NUM>. The solar tracker also comprises a first controller <NUM> which is configured to control the first electric motor <NUM> and move the first set of panels <NUM> to the final angular position depending on the initial angular position determined by the first position sensor <NUM>, and a second controller <NUM> which is configured to control the second electric motor <NUM> and move the second set of panels <NUM> to the final angular position depending on the initial angular position determined by the second position sensor <NUM>.

In this way, each controller <NUM> and <NUM> knows the actual angular position of its respective set of panels <NUM> and <NUM> at all times and may calculate the angle at which each set of panels <NUM> and <NUM> must be moved in order to reach the final angular position. When the controller determines the angle, the controller calculates the speed at which the set of panels must be moved and powers the motor to move the panels at the calculated speed until reaching the required angular position. The operation of each controller <NUM> and <NUM> is described below.

Preferably, the first controller <NUM> is a master controller and the second controller <NUM> is a slave controller, the first controller <NUM> and the second controller <NUM> being connected to one another through a data and power supply line <NUM>. In this way, although each controller controls its respective electric motor independently, the master controller <NUM> may monitor all the operations of the slave controller <NUM>, and the master controller <NUM> may send orders to the slave controller <NUM> and receive data from the slave controller <NUM>.

The solar tracker comprises a plurality of posts <NUM> extending and separated longitudinally along at least one axis X and at least one support structure <NUM> which is supported on the plurality of posts <NUM>. Each support structure <NUM> comprises a main crossbar <NUM> extending along the axis X and a plurality of transverse crossbars <NUM> oriented orthogonally to the main crossbar <NUM>.

Preferably, the position sensors <NUM> and <NUM> are accelerometers. Accelerometers measure linear accelerations in one axis, two axes, or three axes.

The first accelerometer <NUM> is arranged in a part of the support structure <NUM> that supports the first set of panels <NUM> and the second accelerometer <NUM> is arranged in a part of the support structure <NUM> that supports the second set of panels <NUM>. This ensures that the accelerometers are arranged on the support structure <NUM> of the photovoltaic solar panels <NUM>. This favours the detection of the galloping effect since measurement is performed directly in the place where the effect occurs.

Even more preferably, the first accelerometer <NUM> is arranged in an enclosing casing of the first controller <NUM> which is in turn arranged in a part of the support structure <NUM> that supports the first set of panels <NUM>, and the second accelerometer <NUM> is arranged in an enclosing casing of the second controller <NUM> which is in turn arranged in a part of the support structure <NUM> that supports the second set of panels <NUM>. This allows the casing of the controller to hold the accelerometer, whereby a compact device which houses the electronics for controlling the electric motor is obtained.

The schematic example of <FIG> shows a solar tracker with a row of photovoltaic solar panels <NUM>. The solar tracker comprises a plurality of posts <NUM> extending and separated longitudinally along an axis X and a support structure <NUM> which is supported on the plurality of posts <NUM>. The support structure <NUM> comprises a main crossbar <NUM> extending along the axis X and a plurality of transverse crossbars <NUM> oriented orthogonally to the main crossbar <NUM>. The plurality of photovoltaic solar panels <NUM> is arranged on the support structure <NUM>, the first electric motor <NUM> is operatively coupled to a first part <NUM> of the main crossbar <NUM> to apply a rotation to the first part <NUM> of the main crossbar <NUM> and move the first set of panels <NUM> to the final angular position, and the second electric motor <NUM> is operatively coupled to a second part <NUM> of the main crossbar <NUM>, spaced from the first part <NUM>, to apply a rotation to the second part <NUM> of the main crossbar <NUM> and move the second set of panels <NUM> to the final angular position.

Preferably, the first electric motor <NUM> is operatively coupled to a first actuator <NUM> which is arranged on the first part <NUM> of the crossbar longitudinal <NUM> and the second electric motor <NUM> is operatively coupled to a second actuator <NUM> which is arranged on the second part <NUM> of the crossbar longitudinal <NUM>. The actuator <NUM> or <NUM> may be a slew drive, a linear actuator, or any type of actuator commonly used in the photovoltaic sector for coupling to the main crossbar <NUM> of the support structure <NUM> of a solar tracker and rotating the main crossbar <NUM>.

The solar tracker may comprise more than two sets of panels, and each set of panels has an electric motor for moving the set of panels, a position sensor for determining the initial angular position of the set of panels, and a controller for controlling the electric motor and moving the set of panels to the final angular position depending on the initial angular position determined by the position sensor. Furthermore, each motor is operatively coupled to an actuator. For example, <FIG> shows a solar tracker with three rows of photovoltaic solar panels <NUM> and each row has three sets of solar panels. The solar tracker has a first controller <NUM> and several second controllers <NUM> and <NUM>', wherein the first controller <NUM> is a master controller of the solar tracker and the second controllers <NUM> and <NUM>' are slave controllers. The master controller <NUM> is connected to each of the slave controllers <NUM> by means of a respective data and power supply line (which for the sake of clarity is not depicted in <FIG>). Preferably, the master controller <NUM> is located in the centre of the solar tracker.

The plurality of photovoltaic solar panels <NUM> is connected to a power line <NUM> to extract the electric power generated by the photovoltaic solar panels <NUM>, and the first electric motor <NUM> and the second electric motor <NUM> are connected to the power line <NUM> to receive electric power from the power line <NUM>. In this way, the electric power generated by the photovoltaic solar panels <NUM> is utilized to move the sets of panels <NUM> and <NUM>. The power line <NUM> is commonly known in the photovoltaic sector as the solar tracker string, and it is the line through which the electric power generated by each photovoltaic solar panel <NUM> is extracted, which power is generally delivered to a string box, from which electricity is delivered to the grid.

<FIG> and <FIG> show two examples for connecting the controllers <NUM> and <NUM> to the power line <NUM> and controlling the electric motors <NUM> and <NUM>.

As shown in <FIG>, the power line <NUM> extracting the electric power generated by the photovoltaic solar panels <NUM> is the data and power supply line <NUM> which is used for transmitting electric power and communication data between the first controller <NUM> and the second controller <NUM>. In other words, the same physical means are utilized to transmit electric power and communication data between the controllers. In other words, the solar tracker string is used to connect the controllers <NUM> and <NUM> to one another, thereby reducing the tracker cost, since the string is a wiring that is always required in the photovoltaic solar panels <NUM> for power extraction.

As shown in <FIG>, the first controller <NUM> is connected to the power line <NUM> of the plurality of photovoltaic solar panels <NUM> to receive electric power from the power line <NUM>, and the second controller <NUM> is connected to the first controller <NUM> to receive electric power and communication data from the first controller <NUM> through the data and power supply line <NUM>. In this case, unlike <FIG>, a dedicated umbilical cable <NUM> is used to transmit electric power and communication data between the controllers <NUM> and <NUM>. This option of <FIG> uses more wiring than the option of <FIG>, but allows the second controller <NUM> to have simpler electronics that are therefore more cost-effective, since it does not require adapting the power from line <NUM>, given that said function is performed by the first controller <NUM>. For example, line <NUM> has a voltage of <NUM> V, and the first controller <NUM> transforms the voltage from <NUM> V to <NUM> V.

As seen in <FIG> and <FIG>, the first controller <NUM>, acting as the master controller, comprises a DC/DC converter <NUM>, a power unit PWR <NUM>, a microcontroller <NUM>, a driver <NUM>, and the first accelerometer <NUM>. Furthermore, the first controller <NUM> has a battery BAT <NUM>, a communication interface HMI <NUM>, and a communications port COM <NUM>.

The DC/DC converter <NUM> adapts the electric power from the power line <NUM> so that it may be used by the different components of the first controller <NUM>. The power unit PWR <NUM> receives the electric power from the DC/DC converter <NUM> and adapts it so that it can be used by the microcontroller <NUM>.

The microcontroller <NUM> of the first controller <NUM> calculates the final angular position to which all the sets of panels <NUM> and <NUM> of the solar tracker must be moved. The microcontroller <NUM> receives the initial angular position measured by the first accelerometer <NUM> and sends a setpoint signal to the driver <NUM> of the first electric motor <NUM> for it to act on the first actuator <NUM> and move the first set of panels <NUM> to the final angular position. The setpoint signal sent to the driver <NUM> comprises a position signal, a speed signal, and a direction of rotation, and based on said signals, the driver <NUM> powers the first electric motor <NUM>. The position signal has the final angular position to which the first set of panels <NUM> must be moved, and the speed signal has the speed at which the first set of panels <NUM> must be moved in order to reach the final angular position.

The final angular position may be calculated in real time by the microcontroller <NUM> of the first controller <NUM> based on an astronomical algorithm. In other words, the microcontroller <NUM> may calculate the position of the sun depending on the location of the solar tracker (latitude and longitude) and the time of the day. The final angular position may also be sent to the microcontroller <NUM> by an operator from the communication interface HMI <NUM>, for example, to perform maintenance tasks when the photovoltaic solar panels <NUM> are to be moved to a specific position.

The battery BAT <NUM> is optional and may be used to send electric power to the motor in the event that the power obtained from the power line <NUM> is not enough, which occurs, for example, at night when the panels <NUM> do not produce any power. The communications port <NUM> comprises high-level communication protocols such as, for example, ZigBee or Bluetooth, used by the master controller <NUM> to generate the high-level communication network. The controller <NUM> may further have a service communication port for being connected with the microcontroller <NUM> in the event that the communications port <NUM> fails.

The second controller <NUM>, acting as the slave controller, comprises the same elements as the first controller <NUM>, acting as the master, with the exception that it has no communication interface HMI <NUM> nor communications port COM <NUM>.

The microcontroller <NUM> of the second controller <NUM> receives the final angular position to which the second set of panels <NUM> must be moved from the microcontroller <NUM> of the first controller <NUM>. The microcontroller <NUM> of the second controller <NUM> also receives the initial angular position measured by the second accelerometer <NUM>. The microcontroller <NUM> of the second controller <NUM> also receives the speed at which the second set of panels <NUM> must be moved in order to reach the final angular position from the microcontroller <NUM> of the first controller <NUM>. Based on the foregoing, the microcontroller <NUM> of the second controller <NUM> sends a setpoint signal to the driver <NUM> of the second electric motor <NUM> for it to act on the second actuator <NUM> and move the second set of panels <NUM> to the final angular position. The setpoint signal sent to the driver <NUM> of the second controller <NUM> also comprises a position signal, a speed signal, and a direction of rotation, and based on said signals, the driver <NUM> powers the second electric motor <NUM>. The position signal has the final angular position to which the second set of panels <NUM> must be moved, and the speed signal has the speed at which the second set of panels <NUM> must be moved in order to reach the final angular position.

As also shown in <FIG>, the second controller <NUM> also has no DC/DC converter <NUM> nor a battery <NUM>, since in <FIG>, the power unit PWR <NUM> of the second controller <NUM> receives the electric power from the DC/DC converter <NUM> of the first controller <NUM> through the data and power supply line <NUM>. This allows the electronics of the second controller to be simpler and therefore more cost-effective.

In this way, the control method of the solar tracker comprises the following steps:.

To move the first set of panels <NUM> to the final angular position, the first controller <NUM> receives the initial angular position of the first set of panels <NUM> measured by the position sensor <NUM> and determines the angle at which the first set of panels <NUM> must be moved, for example, by subtracting the initial angular position from the final angular position.

Then, the first controller <NUM> determines the direction of rotation and the speed at which the first set of panels <NUM> must be moved in order to reach the final angular position and powers the first electric motor <NUM> in order to reach said final angular position.

To move the second set of panels <NUM> to the final angular position, the second controller <NUM> receives the final angular position from the first controller <NUM>, receives the initial angular position of the second set of panels <NUM> measured by the second position sensor <NUM>, and determines the angle at which the second set of panels <NUM> must be moved, for example, by subtracting the initial angular position from the final angular position.

The second controller <NUM> also receives the speed at which the second set of panels <NUM> must be moved in order to reach the final angular position from the first controller <NUM> and powers the second electric motor <NUM> in order to reach said final angular position. The direction of rotation may be sent to the second controller <NUM> from the first controller <NUM>, or the second controller <NUM> itself may determine the direction of rotation.

The first controller <NUM>, acting as the master, monitors the operation of the second controller <NUM>, acting as the slave, in real time. To that end, the second controller <NUM> sends data about the angular position of the second set of panels <NUM> to the first controller <NUM>. The second controller <NUM> also sends data about the speed at which the second set of panels <NUM> is moved to the first controller <NUM>.

For example, if the two sets of panels <NUM> and <NUM> were to be moved to a final angular position of <NUM>°, with both sets <NUM> and <NUM> being in an initial angular position of <NUM>°, the controllers <NUM> and <NUM> may send a single order to the electric motors <NUM> and <NUM> for them to move the sets of panels <NUM> and <NUM> from <NUM>° to <NUM>°.

When the angle between the initial angular position and the final angular position is less than a certain angle, for example less than <NUM>°, the photovoltaic solar panels <NUM> may be moved between the initial angular position and the final angular position in a single movement, however, when the angle between the initial angular position and the final angular position is greater than a certain angle, for example greater than <NUM>°, the photovoltaic solar panels <NUM> are preferably moved between the initial angular position and the final angular position in more than one movement, being established to that end partial angular positions.

According to the foregoing, after selecting the final angular position of the plurality of photovoltaic solar panels <NUM>, the method comprises the following steps:.

For example, if the sets of panels <NUM> and <NUM> were to be moved to a final angular position of <NUM>°, with both sets of panels <NUM> and <NUM> being in an initial angular position of <NUM>°, the controllers <NUM> and <NUM> may send partial orders to the motors <NUM> and <NUM> for them to move the sets of panels <NUM> and <NUM> from <NUM>° to <NUM>°, then from <NUM>° to <NUM>°, then from <NUM>° to <NUM>°, and repeating the process until reaching <NUM>°. This option allows minimizing the risk of misalignments between the sets of panels <NUM> and <NUM>.

According to one embodiment, the first set of panels <NUM> and the second set of panels <NUM> are moved simultaneously until reaching the final angular position, i.e., all the photovoltaic solar panels <NUM> are moved at the same time.

According to another embodiment, the first set of panels <NUM> and the second set of panels <NUM> are moved sequentially until reaching the final angular position, wherein first the photovoltaic solar panels <NUM> of one set of panels <NUM> are moved, and then the photovoltaic solar panels <NUM> of the other set of panels <NUM> are moved.

Preferably, when the photovoltaic solar panels <NUM> of the two sets of panels <NUM> and <NUM> are arranged on the same main crossbar <NUM> of the support structure <NUM>, the control method comprises the following steps:.

In this way, instead of moving the actuators <NUM> and <NUM> at the same time, the actuators <NUM> and <NUM>, and therefore the sets of panels <NUM> and <NUM>, are moved sequentially, at intervals, which allows the maximum electric power required for moving the photovoltaic solar panels <NUM> of the solar tracker to be reduced, in exchange for a small torsion in the main crossbar <NUM> of the support structure <NUM>, and generally a lower advancement speed.

Claim 1:
Solar tracker comprising:
a plurality of photovoltaic solar panels (<NUM>) with a first set of panels (<NUM>) and a second set of panels (<NUM>);
a plurality of posts (<NUM>) extending and separated longitudinally along an axis (X);
a support structure (<NUM>) which is supported on the plurality of posts (<NUM>), the support structure (<NUM>) comprises a main crossbar (<NUM>) extending along the axis (X) and a plurality of transverse crossbars (<NUM>) oriented orthogonally to the main crossbar (<NUM>), the plurality of photovoltaic solar panels (<NUM>) is arranged on the support structure (<NUM>);
a first electric motor (<NUM>) which is operatively coupled to a first part (<NUM>) of the main crossbar (<NUM>) to apply a rotation to the first part (<NUM>) of the main crossbar (<NUM>) and move the first set of panels (<NUM>) to a final angular position; and
a second electric motor (<NUM>) which is operatively coupled to a second part (<NUM>) of the main crossbar (<NUM>), spaced from the first part (<NUM>), to apply a rotation to the second part (<NUM>) of the main crossbar (<NUM>) and move the second set of panels (<NUM>) to the final angular position;
wherein the solar tracker further comprises:
a first position sensor (<NUM>) for determining an initial angular position of the first set of panels (<NUM>);
a first controller (<NUM>) configured to control the first electric motor (<NUM>) and move the first set of panels (<NUM>) to the final angular position depending on the initial angular position determined by the first position sensor (<NUM>);
a second position sensor (<NUM>) for determining an initial angular position of the second set of panels (<NUM>); and
a second controller (<NUM>) configured to control the second electric motor (<NUM>) and move the second set of panels (<NUM>) to the final angular position depending on the initial angular position determined by the second position sensor (<NUM>).