Method and device for controlling an agrivoltaic system based on the water potential of cultivated plants

Abstract

Control device (21) for an agrivoltaic system (10) comprising an array of solar panels (11) located above an area (32) containing a set of cultivated plants, each solar panel being movable in orientation by means of actuators (13), said control device (21) comprising a computer (211) for determining control signals (25) adapted to drive a rotation of the solar panels so as to adapt the incidence of the sun's rays on said area according to the sun's path and agricultural objectives including the water potential of said cultivated plants, and an interface for transmitting said control signals (25) to said actuators (13). Figure for the abstract: Figure 1

Description

Title of the invention: Method and device for controlling an agrivoltaic system based on the water potential of cultivated plants technical field

[0001] The field is that of agrivoltaic systems enabling photovoltaic production on a plot of agricultural land. The proposal relates more specifically to a method for controlling such an agrivoltaic system, allowing for the optimization of agricultural production and photovoltaic energy production. TECHNOLOGICAL BACKGROUND

[0002] A photovoltaic system works by converting light energy, produced by solar radiation, into electricity using one or more solar panels.

[0003] These solar panels occupy a larger area of ​​land the higher the targeted electricity production. However, land is also necessary for agricultural production. Photovoltaic production and agricultural production thus appear to be in competition because they use the same land resources, thereby hindering the development of photovoltaic systems.

[0004] However, as early as the 1980s, Adolf Goetzberger and Armin Zastrow formalized the idea of ​​combining photovoltaic electricity production and agricultural production to improve overall productivity. Thus, agrivoltaic systems, reconciling the two objectives, gradually developed, particularly in Asia and Japan in the 2000s.

[0005] An agrivoltaic (or agri-photovoltaic) system refers to an approach that combines agriculture and solar energy production on the same plot of land. The principle is based on installing solar panels above or near agricultural crops, with the aim of avoiding competition for land access and even maximizing synergies between these two activities. Generally, the solar panels are placed in an elevated or adjustable manner to allow sufficient sunlight to reach the crops at ground level. These panels can be fixed or mobile, making it possible to optimize both photosynthesis and energy production.

[0006] Such an approach is favored by certain political authorities. In France, for example, the APER law (Acceleration of Renewable Energy Production), adopted on March 10, 2023, aims to strengthen the development of renewable energies to achieve the objectives of energy transition and carbon neutrality. It encourages an equitable sharing of the economic benefits of projects renewable energy, particularly with local authorities. This includes pilot projects for agrivoltaics, combining agricultural production and solar energy.

[0007] Such systems are described for example in US patent application 2021 / 0211091.

[0008] A method of controlling solar panels has been proposed so that they follow the sun's path by orienting them, using actuators, substantially perpendicular to the sun's rays. This method, called "solar tracking," optimizes photovoltaic production, but this optimization can negatively impact the needs of cultivated plants, which may then no longer receive sufficient solar radiation.

[0009] Other proposals have been made concerning the method of controlling solar panels in order to find a compromise between the production of photovoltaic energy and agricultural production dependent on photosynthesis.

[0010] Such systems are described for example in patent EP3122172 or in patent application FR3134282.

[0011] These systems generally describe an automatic control based on environmental data that can be measured locally by means of sensors, for example rainfall, temperature sensors, relating to the environment in which the agricultural cultivation takes place.

[0012] Furthermore, the control system can also aim to protect crops from climatic hazards such as high temperatures, periods of drought, frost, hail, heavy rainfall, wind, etc. The solar panels can then be oriented so as to form a barrier against the climatic phenomenon harmful to the crop.

[0013] However, in practice these mechanisms prove insufficient to capture the true physiological needs of cultivated plants, environmental parameters also having different effects on crop growth depending on the cultivated species.

[0014] There is therefore a real need to improve the processes and devices for controlling agrivoltaic systems in order to optimize agricultural production while maintaining a high level of photovoltaic production. Description of the invention

[0015] The invention aims to improve the state of the art. In particular, it aims to take into account the physiological health of the plant, especially in real time, in order to adapt the control of the solar panels.

[0016] More specifically, a method for controlling an agrivoltaic system comprising a set of solar panels located above an area comprising a set of cultivated plants, each solar panel being movable in orientation by means of actuators, said method comprising a determination of control signals adapted to drive a rotation of the solar panels so as to adapt the incidence of the sun's rays on said area according to the sun's path and agricultural objectives including a water potential of said cultivated plants, by a control device, then an emission of said control signals to said actuators.

[0017] According to preferred embodiments, the invention comprises one or more of the following features which can be used separately or in partial combination with each other or in total combination with each other: - said control device determines an operating mode based on said water potential, between a first operating mode in which said control signals are provided to maintain an orientation of said solar panels over time minimizing the incidence of the sun's rays on said area, and a second operating mode in which said control signals are provided to maintain an orientation of said solar panels over time maximizing said incidence; - said control signals are adapted to reduce the incidence of sunlight on said area when said water potential is below a threshold; - said control signals are determined by means of a nomogram providing at least one angle of rotation as a function of at least one time data point; - said water potential is provided by at least one sensor located near a plant in said group of cultivated plants; - said sensor is a micro-tensiometer with a needle inserted into the tissues of said plant or a dendrometer, or a sap flow sensor; - said water potential is estimated from a plurality of measurements provided by environmental sensors; - The estimation is performed using a pre-trained predictive model.

[0018] Another object relates to a control device for an agrivoltaic system comprising an array of solar panels located above an area containing a set of cultivated plants, each solar panel being movable in orientation by means of actuators, said control device comprising a computer for determining suitable control signals to drive a rotation of the solar panels so as to adapt the incidence of the sun's rays on said area according to of the sun's path and agricultural objectives including a water potential of said cultivated plants, and an interface for emitting said control signals to said actuators.

[0019] Another aspect relates to a control system comprising a control device as previously described, as well as a set of water potential sensors.

[0020] The system may also include environmental sensors, for example for air temperature and humidity, and soil temperature and humidity.

[0021] Another aspect concerns a system composed of a control system as described and an agrivoltaic system.

[0022] Another aspect relates to a computer program suitable for implementation on a control device of an agrivoltaic system, the program comprising code instructions which, when these instructions are executed by a processor, lead the latter to implement at least some of the steps of the process described above.

[0023] Another aspect relates to a data carrier on which at least one series of program code instructions has been stored for the execution of at least some of the steps of a process as previously defined. Brief description of the drawings

[0024] Other aspects, objects, advantages and features of the invention will become more apparent upon reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and made with reference to the accompanying drawings in which: - Fig. 1 schematically represents an agrivoltaic system according to one embodiment; - [Fig.2] details a functional view of an example of a control device for an agrivoltaic system according to one embodiment; - Figures 3A and 3B illustrate two modes of operation of a system agrivoltaics according to implementation methods; - Fig. 4 illustrates the evolution of the water potential of at least one cultivated plant according to different operating modes of an agrivoltaic system. DETAILED DESCRIPTION OF SPECIFIC METHODS OF IMPLEMENTATION

[0025] Fig. 1 illustrates schematically an example of an agrivoltaic system 10.

[0026] This system comprises a set of solar panels 11 positioned above an area 32 containing a set of cultivated plants. This cultivated area may be a soil area, but soilless cultivation may also be considered. Typically, solar panels can be supported by rigid, substantially vertical posts anchored to the ground. The solar panels can be positioned at a height (typically a few meters) suitable for good air circulation between the crops and the underside of the panels, as well as for the movement of personnel involved in crop management and, potentially, agricultural equipment. However, different arrangements are possible, depending on the type of crop and / or the operator's preferences.

[0027] Solar panels, or photovoltaic panels, are designed to convert incident light rays into electrical energy using the photovoltaic effect. Such a panel is known per se.

[0028] The solar panels 11 are opaque to light. In other words, the sunlight that strikes a photovoltaic panel is mostly absorbed by it, and only partially reflected, but no rays can pass through it and thus reach the area 32 supporting the cultivated plants. The photovoltaic panels therefore form a cone of shadow, the solid angle (and surface area on the ground) of which depends on the orientation of the panels relative to the position of the sun.

[0029] The solar panels 11 can be movable relative to the uprights 12, by means of actuators 13.

[0030] Different types of movements can be envisaged, but they are generally rotational about at least one axis. This axis can be parallel to the ground and perpendicular to a principal direction of sunlight.

[0031] This main direction is generally substantially the north-south axis, but it can be adapted according to latitude and / or local geography. For example, for an agrivoltaic system 10 located in the northern hemisphere, if the southern direction is obstructed by a mountain range, it may be preferable to choose a main direction oriented towards the opening of the valley located further east or west.

[0032] The installer of the agrivoltaic system will therefore be able to take into consideration different geographical and contextual data to determine this main direction of sunlight, in the case where a rotation on a single axis is made possible by the actuators 13. In the case where more degrees of freedom are offered by the structure of the system 11 and by the actuators 13, the installation of the system in its environment can possibly be more arbitrary.

[0033] According to one embodiment, the solar panels are also orientable, by means of the actuators 13, along a second axis of rotation. This second axis of rotation can be a vertical axis, thus allowing the panels to be oriented towards the different cardinal points, and in particular towards the east and west from a "neutral" position corresponding to the main direction of sunlight.

[0034] Fig. 3A illustrates an operating mode of the agrivoltaic system in which the solar panels 1 IA, 1 IB, 1 IC are oriented so as to maximize the interception of the sun's rays 30 by the solar panels, and, consequently, to minimize the incidence of these rays on the area 32 containing the cultivated plants.

[0035] This configuration optimizes the operation of electricity production by photovoltaic effect.

[0036] In return, each solar panel 11 A, 1 IB, 1 IC generates a shade cone, respectively 31 A, 31 B, 31 C. Depending on the configuration of the agrivoltaic system, these shade cones can generate a continuous shaded region covering the entire cultivated area 32. This configuration therefore minimizes the reception of light energy by the cultivated plants.

[0037] This configuration corresponds to an orientation of the solar panels as perpendicular as possible to the sun's light rays 30. This search for perpendicularity is constrained by the degrees of freedom offered by the agrivoltaic system.

[0038] Different embodiments are therefore possible in this respect, depending on the agrivoltaic system model, and in particular on the junction and actuators of the solar panels in relation to the uprights 12. If the solar panels are orientable along two axes of rotation, it is then possible to orient them perpendicularly to the sun's rays precisely.

[0039] Thus, a first axis of rotation can allow the solar panel to be oriented according to the elevation of the sun 30, while a second axis of rotation can allow the solar panel to be oriented in azimuth.

[0040] Furthermore, the sun follows an east-to-west path during the course of a day. Therefore, the orientation of the solar panels may need to be adjusted over time to adapt to the sun's path.

[0041] A mode of operation called "solar tracking" consists of making this adaptation over time to maintain the configuration illustrated in [Fig.3A] in which the incidence of the sun's rays on the cultivated area 32 is minimized.

[0042] On the contrary, [Fig. 3B] illustrates an operating mode of the agrivoltaic system in which the solar panels 11A, 11B, 11C are oriented so as to minimize the interception of the sun's rays 30 by the solar panels, and, consequently, to maximize the incidence of these rays on the area 32 containing the cultivated plants. The solar panels are oriented so as to be substantially parallel to the sun's rays.

[0043] This configuration optimizes the sunlight in the cultivated area 32 but minimizes electricity production.

[0044] Thus, each solar panel 1 IA, 1 IB, 1 IC generates a shade cone, respectively 31 A, 31B, 31C. Depending on the configuration of the agrivoltaic system, these shade cones can be extremely reduced, so that the cultivated area 32 is almost continuously sunny.

[0045] Similar to the arrangement illustrated in [Fig. 3A], the sun follows an east-to-west path during the course of a day. Therefore, the orientation of the solar panels may need to be adjusted over time to adapt to the sun's path.

[0046] A mode of operation called "anti-solar tracking" (or "anti-tracking" in English) consists of making this adaptation over time to maintain the configuration illustrated in [Fig.3B] in which the incidence of the sun's rays on the cultivated area 32 is maximized.

[0047] A control device 21 on [Fig. 1] is also provided to transmit control signals 25 adapted to drive the rotation of the solar panels 11 A, 1 IB, 1 IC so as to adapt the incidence of the sun's rays on the cultivated area 32 according to the sun's path. These control signals may include rotation angles to be applied to the actuators of each solar panel. These rotation angles include an elevation angle and, possibly, an azimuth angle.

[0048] Other modes of operation than those illustrated in figures 3a and 3b are also possible.

[0049] According to the proposed method, the control signals 25 are determined by the control device 21 as a function of the sun's path and agricultural objectives including data representative of a stress on cultivated plants. This stress is a water stress that can be measured by the water potential of the plants.

[0050] Water potential is a physical variable with the dimensions of pressure that quantifies the energy level of the water molecules in a solution, in other words, the "force" with which this solution retains its water molecules. Water potential reflects the state of water in plant tissues and influences the plant's ability to absorb and transport water from the roots to the leaves.

[0051] The water potential of a plant can be seen as the resulting energy of different forces:

[0052] W = P + n + t + p

[0053] P represents a turgor pressure potential, and corresponds to the pressure exerted by water on the cell walls. When cells are well hydrated, turgor pressure is high (P positive). In the case of dehydration, P decreases, or even becomes zero.

[0054] 77 represents the osmotic potential linked to the presence of dissolved solutes (sugars, ions, etc.) in the cells.

[0055] T represents the matrix potential, i.e. the retention forces exerted by the solid surfaces (cell walls...).

[0056] P represents the gravitational potential which is negligible for cultivated plants and only takes on a substantial value for tall plants such as trees.

[0057] For a cultivated plant, water stress occurs when the water potential becomes too low (i.e., too high in absolute value, the water potential being negative). This stress indicates a lack of water in the plant tissues.

[0058] This water potential is therefore not an environmental parameter but, on the contrary, is linked to the internal physiology of the cultivated plant and is thus representative of the plant's health and its ability to grow. It is therefore important to maintain the water potential above a certain level, this level potentially depending on the type of plant and crop.

[0059] In order to enable control of the agrivoltaic system taking into account the water potential of the cultivated plants, a control system 20 can be provided, comprising sensors 22, 23, 24 placed within the cultivated area 32 and a control device 21 adapted to transmit control signals to the actuators of the agrivoltaic system according to the data provided by the sensors.

[0060] Fig. 2 details a functional view of an example of a control device 21 of an agrivoltaic system 10 according to one embodiment.

[0061] This control device 21 includes a computer 211 designed to determine control signals 25 adapted to drive the rotation of the solar panels 11 so as to adjust the incidence of sunlight on the area 32 according to the sun's path and agricultural objectives, including the water potential of cultivated plants. It also includes an interface designed to transmit these control signals 25 to the actuators 13 of the solar panels 11.

[0062] This interface can be adapted for wired or radio transmission to the actuators. Communication protocols such as Modbus or MQTT (for "Message Queuing Telemetry Transport") can be used.

[0063] The control device 21 determines the control signals 25 from data provided by sensors positioned within the cultivated area 32.

[0064] According to one embodiment, the water potential can be measured by at least one sensor 22 located near one plant in the set of cultivated plants.

[0065] Optionally, several sensors can be positioned in different locations within the growing area. This allows for obtaining an average measurement over several areas and to smooth out disparities and biases that may be linked to other phenomena. This can be all the more interesting as the cultivated area 32 is extensive.

[0066] Also, several sensors can be provided when several plants of different species or varieties are grown in the same cultivated area 32, in order to estimate the water stress for each species or variety.

[0067] Different sensors 22 can be used to measure or estimate, directly or indirectly, the water potential of a plant.

[0068] An example of a sensor could be a dendrometer, which makes it possible to measure variations in the diameter of a stem. These variations are correlated with the water potential of the stem in question.

[0069] Another example of sensors 22 could be a sap flow sensor. Measuring the sap flow in the plant makes it possible to deduce the plant's water potential.

[0070] These sensors 22 can also be micro-tensiometers in direct contact with the plant tissues. These sensors can thus collect real-time data estimating the plant's water potential.

[0071] Various micro-tensiometers exist on the market and can be used within the framework of the proposed process.

[0072] According to one embodiment, the sensors 22 have a needle for insertion into the plant tissues. A small needle or probe is inserted into the stem or trunk of the plant. An internal sensor detects the pressure required to extract water from the tissues or measures the capillary tension. These measurements are often linked to a data logger. The sensor has a wired or wireless interface for transmitting the measurements.

[0073] Depending on their type and / or the farmer's choice, the sensors can be attached (or inserted) to a stem, a leaf, the trunk, the roots of the plant, etc.

[0074] The data measured by these sensors 22 can be directly provided to the control device 21, or in particular to the computer 211 of the control device 22.

[0075] According to another embodiment, the water potential is estimated from a plurality of measurements provided by environmental sensors 23, 24.

[0076] These environmental sensors can be of different types in order to capture a holistic view of the environment allowing a better estimation of the water potential of plants located in this environment.

[0077] According to one embodiment, the data measured by the environmental sensors include: - Wind speed, air temperature, air humidity: these measurements can be provided by a local weather station 23. - Soil temperature, soil moisture: these measurements can be provided by at least one sensor 24 located on and / or in the soil of the cultivated area 32.

[0078] A plurality of sensors may be provided in order in particular to obtain measurements of humidity and / or temperature at different depths of the soil.

[0079] It has been experimentally determined that these different data influence the water potential and that they can be sufficient to provide a sufficiently accurate estimate.

[0080] As previously explained for the water potential sensor 22, several environmental sensors 23, 24, distributed over the cultivated area 32 can be provided in order to improve the estimation of the state of the environment and to take into account phenomena that are too local.

[0081] A calculator 212 may be provided to determine a water potential from these environmental measurements.

[0082] In [Fig.2], the calculator 212 is shown as distinct from the calculator 211, but This is a functional view.

[0083] From a hardware implementation point of view, the computers 211, 212 include at least one processor and memories and possibly specialized circuits, these elements being able to be partially or totally shared for the two computers.

[0084] The calculation of the water potential by the computer 212 can be done in real time, so that it is transparent to the computer 211 whether the water potential comes directly from a micro-tensiometer type sensor 22 or from an estimate from environmental sensors.

[0085] According to one embodiment, the calculator 211 can take into account both types of data to determine the control signals. For example, it can be based primarily on the water potential provided directly by the sensor 22 associated with the plants, but, for example in the event of a malfunction, consolidate its provided values ​​with the estimate provided from environmental measurements.

[0086] Different embodiments are possible for estimating a water potential from measurements provided by environmental sensors 23, 24.

[0087] According to one embodiment, the estimation is carried out from a physical model comprising a set of physical equations linking the water potential to the available measurements.

[0088] Studies exist to estimate water potential as a function of environmental variables. For example, see the article by Tuzet et al., (2017) “Modelling hydraulic functioning of an adult beech stand under non-limiting soil water and severe drought condition”, DOI: 0.1016 / j.ecolmodel.2017.01.007

[0089] According to one embodiment, the estimation is carried out using a previously trained predictive model.

[0090] The training, or learning, of the predictive model can be supervised, that is to say carried out on the basis of a training set comprising both input data (i.e. measurements from environmental sensors) and desired outputs, or labels, i.e. a corresponding water potential.

[0091] Learning can be carried out using data from the operating site, i.e., the cultivated area 32 under consideration. It is then necessary to have both a water potential sensor 22 and environmental sensors 23, 24 on this cultivated area. It is then possible to create a training set by combining measurements taken by the environmental sensors and a water potential measurement taken at substantially the same time.

[0092] In a manner known per se, a training set containing a sufficient number of such associations must be constituted in order to allow sufficient convergence of the predictive model.

[0093] When the learning is complete, the predictive model can be used to predict a water potential from environmental measurements, and it is then no longer necessary to have direct measurements of the water potential.

[0094] Training can also be carried out using data from a different site, i.e., not from cultivated area 32. This training can be done using the same methods as previously described. Once the training is complete, the predictive model can be transferred to the farm site.

[0095] A complementary approach could be to combine the two approaches by implementing a predictive model trained at another site, then finalizing the training at the operating site. This can shorten the on-site training phase by using a pre-trained model.

[0096] It is also possible to carry out the preliminary training on a set of different sites in order to allow for consideration of a greater variability of data, in particular due to different environments.

[0097] The water potential can therefore be determined in different ways.

[0098] This water potential is representative of water stress in the plants of the zone cultivated 32. In order to ensure a good agricultural yield, both quantitative and qualitative, this water stress must be constantly under control.

[0099] This control may not aim to systematically minimize water stress. For some types of crops, in fact, a certain level of water stress can improve crop development, particularly in terms of quality. This is the case, for example, in viticulture, where moderate water stress may be desirable.

[0100] According to one embodiment, thresholds can be set, which can be a function of the type of plants in the cultivated area 32.

[0101] For example, for vine stocks, the following thresholds can be defined: - Water comfort: water potential greater than -0.5 MPa (megapascals). - Moderate water stress: water potential between -0.5 MPa and -1 MPa, - Stress, or significant water constraint: water potential between -1 MPa and -1.5 MPa. - Severe water stress: water potential below -1.5 MPa.

[0102] Of course, other thresholds and other breakdowns are possible.

[0103] For a given type of plant, these thresholds can be adapted according to various factors such as soil type, terroir, and an objective or strategy defined by the farmer.

[0104] It is noted that the decrease in water potential is linked to evaporation and transpiration of the plant, that is to say, the reduction in the amount of water contained in the plant due to its transformation into water vapor under the effect of sunlight. This water loss generates water stress, or even true water stress, which can be detrimental to the plant's development. In the most extreme cases, or in the event of a prolonged state of sustained stress, the plant may die.

[0105] The farmer can set a desired range of values ​​for the water potential. This range of values ​​corresponds to the species and, possibly, the variety of the cultivated plant, but also to an objective or strategy.

[0106] In order to influence plant growth and quality, the operator can change the level of water stress. Indeed, for some plants, excessive water availability can promote better development, but at the expense of plant quality, which may result in less flavor and nutritional value. In viticulture, for example, it is advantageous to impose water stress on grapevines to increase sugar content, in proportions that may depend on the grape variety and the type of wine intended.

[0107] Thus, controlling the water potential of cultivated plants makes it possible to optimize their development not only quantitatively, but also qualitatively.

[0108] According to the proposed process, in order to prevent the water potential from being too low, resulting in an excessive level of water stress or constraint, the control device 21 determines control signals, intended for the actuators of the solar panels of the agrivoltaic system which are adapted to limit the transpiration of the cultivated plants.

[0109] To do this, it is possible to orient the solar panels so as to reduce the incidence of the sun's rays on the cultivated area 32.

[0110] In other words, the control device 21 can determine control signals that are a function of the water potential. Other agricultural objectives can also potentially be taken into account in determining the control signals.

[0111] According to one embodiment, these control signals are adapted to reduce the incidence of sunlight on the cultivated area 32 when the water potential is below a threshold. This threshold may correspond to the levels mentioned above, for example -1 MPa in the case of grapevines.

[0112] According to another embodiment, a more continuous control can be implemented, without the use of thresholds, for example by orienting the solar panels so that the incidence of the sun's rays is inversely proportional to the water potential: the more the water potential decreases, the more the solar panels will limit the incidence of the sun's light rays, in order to limit plant transpiration.

[0113] Other laws linking the control of solar panel actuators to water potential can be established, aiming to limit plant transpiration in order to maintain a water potential within a desired range of values.

[0114] This control of the orientation according to the water potential can also be advantageously combined with the management of the operating mode of the agrivoltaic system during a day.

[0115] More specifically, as previously mentioned, the control device 21 can determine an operating mode based on said water potential, among - a first operating mode in which the control signals are designed to maintain an orientation of the solar panels 11 over time minimizing the incidence of sunlight 30 on the cultivated area 32, and, - a second mode of operation in which the control signals are designed to maintain an orientation of the solar panels 11 over time maximizing the incidence of the sun's rays.

[0116] In other words, if the water potential indicates satisfactory water comfort or constraint, the second mode, known as "anti-tracking", is selected. If, on the contrary, the water potential indicates excessive water stress (relative to the thresholds or other parameters set by the farmer), then the first mode, known as "solar tracking", is selected.

[0117] In this way, over the course of a day, the incidence of sunlight, which directly impacts plant transpiration, can be regulated according to a state of water stress measured on the plants in the cultivated area 32.

[0118] It is noted that other operating modes besides the first and second modes described can also be defined. For example, intermediate operating modes can be considered, such as compromises between maximizing and minimizing the incidence of light rays on the ground.

[0119] Depending on the measured water potential, a change in operating mode can be determined during the day. This allows for dynamic adaptation to the physiological conditions of cultivated plants.

[0120] The determination of the control signals from the operating modes can be carried out on the basis of a nomogram 213, for example a table, which, for a time data, provides the corresponding orientation data in order to control the actuators of the solar panels.

[0121] Thus, the abacus 213 can provide at least one angle of rotation (for example in elevation and azimuth) as a function of a time data, for a selected operating mode.

[0122] The time data includes one hour, in order to allow the sun's movement from east to west during a day.

[0123] This course varies depending on the day of the year. Also, the time data can also include a day of the year or other seasonal data (week of the year, etc.) depending on the desired or available level of precision.

[0124] Thus, the calculator 211 of the control device 21, in collaboration with the nomogram 213, can determine an elevation angle and / or an azimuth angle as a function of the date and time, for each operating mode.

[0125] Figure 4 illustrates examples of the evolution of the water potential of at least one cultivated plant under different operating modes of the agrivoltaic system. The curves shown are purely indicative and are intended primarily to illustrate the following explanations.

[0126] Three curves 41, 42, 43 provide evolutions of the water potential PH as a function of time t.

[0127] As explained previously, the water potential is negative. A first region 44, above a first threshold, corresponds to a water comfort zone. A second region 45, between this threshold and a second threshold, corresponds to moderate water constraint, and a third region 46, beyond this second threshold, corresponds to water stress (or severe water constraint).

[0128] Curve 41 corresponds to an evolution of the water potential over time when the agrivoltaic system is placed in a solar tracking operating mode, minimizing the impact of light energy on the plants in the cultivated area. It can be seen that despite fluctuations related to Despite various parameters (daytime and nighttime periods, watering, etc.), the curve remains substantially within region 44, corresponding to optimal water conditions. However, insufficient light energy can negatively impact the growth of cultivated plants.

[0129] Curve 42 corresponds to the anti-tracking operating mode, maximizing the impact of light energy on the cultivated area. The curve oscillates between regions of moderate water constraint, 45, and water stress, 46.

[0130] Curve 43 corresponds to optimized operation according to an embodiment of the proposed process, in which the agrivoltaic system is controlled based on measurements of the water potential of the cultivated plants. This control makes it possible to obtain a curve 43 that corresponds to constraints that can be parameterized.

[0131] In the illustrated situation, curve 43 remains in the region 45 of moderate water stress. This curve corresponds to an interesting situation for plants that benefit from such moderate water stress, such as certain grapevines depending on the objectives and strategy of the winegrower: water stress makes it possible to increase the sugar content in the grape juice that will be pressed.

[0132] Incidentally, this curve corresponds to a behavior allowing a greater generation of electrical energy than curve 42 which corresponds to maintaining the agrivoltaic system in the anti-following operating mode.

[0133] A particular embodiment of the proposed process may benefit from predictive information available to the control device 21.

[0134] Thus, if climate data forecasts are available (temperature, solar radiation, rainfall, wind speed, etc.), it is possible to define and implement scenarios for the evolution of water potential based on the control of the solar panel actuators. This allows us to anticipate future weather variations and modify the control of the actuators.

[0135] Thus, if a rain event is expected in the short or medium term, the control device can adapt the control of the agrivoltaic system to increase the incidence of sunlight before this event (for example by switching to an anti-following operating mode), even if this generates a decrease in the water potential of the cultivated plants (which may temporarily enter a state of water stress), insofar as the sunshine is estimated to be temporary and followed by rain.

[0136] Of course, the present invention is not limited to the examples and embodiment described and illustrated. In particular, it is susceptible to numerous variations accessible to those skilled in the art.

Claims

Demands

1. Method of controlling an agrivoltaic system (10) comprising a set of solar panels (11) located above an area (32) comprising a set of cultivated plants, each solar panel being movable in orientation by means of actuators (13), said method comprising determining control signals (25) adapted to control a rotation of the solar panels so as to adapt the incidence of the sun's rays on said area according to the sun's path and agricultural objectives including a water potential of said cultivated plants, by a control device (21), then emitting said control signals (25) to said actuators (13).

2. A method according to the preceding claim, wherein said control device (21) determines an operating mode as a function of said water potential, among a first operating mode in which said control signals are provided to maintain an orientation of said solar panels (11) over time minimizing the incidence of the sun's rays (30) on said area (32), and a second operating mode in which said control signals are provided to maintain an orientation of said solar panels (11) over time maximizing said incidence.

3. A method according to any one of the preceding claims, wherein said control signals are adapted to reduce the incidence of sunlight on said area when said water potential is below a threshold.

4. A method according to any one of the preceding claims, wherein said control signals are determined by means of a nomogram (213) providing at least one rotation angle as a function of at least one time datum.

5. A method according to any one of claims 1 to 4, wherein said water potential is supplied by at least one sensor (22) located in the vicinity of a plant of said group of cultivated plants.

6. A method according to the preceding claim, wherein said sensor is a micro-tensiometer having a needle inserted into the tissues of said plant, or a dendrometer, or a sap flow sensor

7. A method according to any one of claims 1 to 4, wherein said water potential is estimated from a plurality of measurements provided by environmental sensors (23, 24).

8. Method according to the preceding claim, wherein the estimation is carried out from a previously trained predictive model (212).

9. A computer program capable of being implemented by a control device (21) of an agrivoltaic system (10), the program comprising code instructions which, when executed by a processor, cause the processor to carry out the steps of the process defined in any one of claims 1 to 4, 7 or Q

10. O. Control device (21) for an agrivoltaic system (10) comprising an array of solar panels (11) located above an area (32) comprising an array of cultivated plants, each solar panel being movable in orientation by means of actuators (13), said control device (21) comprising a computer (211) for determining control signals (25) adapted to drive a rotation of the solar panels so as to adapt the incidence of the sun's rays on said area according to the sun's path and agricultural objectives including a water potential of said cultivated plants, and an interface for transmitting said control signals (25) to said actuators (13).