Method and system for determining nighttime temperature using a photovoltaic module

Abstract

Method and system for determining a night temperature using a photovoltaic module This description relates to a method for determining an ambient night temperature Ta' in a system comprising a photovoltaic module (104), the method comprising: a) determining, using an electronic processing device (110), from measurements of the short-circuit current Isc and measurements of the open-circuit voltage Voc of the photovoltaic module, a first value Ta1 representative of the ambient outdoor temperature in the vicinity of dawn on a first day and a second value Ta2 representative of the ambient outdoor temperature in the vicinity of dusk on the first day;(etb) calculate, using the electronic processing device, from the first value Ta1 and the second value Ta2, using a predefined mathematical function Ta', a set of one or more values ​​representative of the evolution of the ambient nighttime outside temperature during the night following said first day. Figure for the abbreviation: Fig. 2;

Description

Title of the invention: Method and system for determining nighttime temperature using a photovoltaic module. Technical field

[0001] This description relates generally to systems integrating photovoltaic modules, and more particularly to a method and system for determining a nighttime temperature using a photovoltaic module. Prior art

[0002] Numerous systems comprising one or more photovoltaic modules configured to power a load, for example an electric battery, have been proposed.

[0003] In many situations, it may be desirable to measure or estimate a temperature within the system or outside the system, for example in order to control an element of the system accordingly.

[0004] To achieve this, a dedicated temperature probe is conventionally used for this measurement. However, integrating such a probe into the system can present technical difficulties and lead to additional costs.

[0005] Methods and systems for measuring ambient temperature using a photovoltaic module have already been proposed, for example in French patent application No. FR2009735 (application number) filed on September 24, 2020, in French patent application No. FR2201446 (application number) filed on February 18, 2022, and in French patent application No. FR2306348 (application number) filed on June 20, 2023, in which an outside ambient temperature is calculated from a measurement of a short-circuit current and an open-circuit voltage of the photovoltaic module.

[0006] These systems advantageously allow the ambient temperature in the vicinity of the photovoltaic module to be determined without requiring a dedicated temperature probe or a dedicated temperature sensor.

[0007] One limitation of these systems is that they only allow measurement of the outside ambient temperature during so-called daytime use phases of the system, during which the photovoltaic module receives significant solar radiation.

[0008] We are particularly interested here in determining the ambient temperature during nighttime use phases of a system comprising a photovoltaic module. Summary of the invention

[0009] One embodiment provides a method for determining an ambient nighttime outdoor temperature Ta' in a system comprising a photovoltaic module, the method comprising the following steps: a) to determine, using an electronic processing device, from measurements of the short-circuit current Isc and measurements of the open-circuit voltage Voc of the photovoltaic module, a first value Tai representing the ambient outside temperature near dawn on the first day and a second value Ta2 representing the ambient outside temperature near dusk on the first day; and b) calculate, using the electronic processing device, from the first value Tai and the second value Ta2 determined in step a), using a predefined mathematical function Ta', a set of one or more values ​​representative of the evolution of the ambient night outside temperature during the night following said first day.

[0010] According to one embodiment, the mathematical function Ta' is a linear, Gaussian, polynomial, spline, or exponential relaxation function.

[0011] According to one embodiment, the mathematical function Ta' is an exponential relaxation function defined by the following relation: [Math 4] T a (h, Tal Ta2) = Tal+(Ta2-Tal) xexp( -ax (h-h2) ) where h is a time variable, a is a relaxation parameter and h2 is an instant corresponding to twilight of the first day.

[0012] According to one embodiment, the relaxation parameter a is stored in a memory of the electronic processing device.

[0013] According to one embodiment, the first Tai value is determined from one or more daytime ambient temperature values, each daytime ambient temperature value being calculated from a measurement of the short-circuit current Isc and a measurement of the open-circuit voltage Voc of the photovoltaic module carried out in the vicinity of dawn.

[0014] According to one embodiment, the second value T.,2 is determined from one or more daytime ambient temperature values, each daytime ambient temperature value being calculated from a measurement of the short-circuit current Isc and a measurement of the open-circuit voltage Voc of the photovoltaic module carried out in the vicinity of dusk.

[0015] According to one embodiment, in step a), the value of the short-circuit current Isc of the photovoltaic module is determined by measuring a voltage across a shunt resistor connected to the terminals of the photovoltaic module.

[0016] According to one embodiment, the value of the shunt resistance is such that the voltage across the shunt resistance when measuring the short-circuit current Isc of the photovoltaic module is less than 5% of the open-circuit voltage Voc of the photovoltaic module.

[0017] According to one embodiment, the method further comprises a step of controlling an electrically controllable element of the system taking into account at least one value of the night ambient temperature calculated in step b).

[0018] Another embodiment provides for a system comprising a photovoltaic module and an electronic processing device configured to implement the aforementioned process.

[0019] According to one embodiment, the system includes a motorized shading device powered by the photovoltaic module. Brief description of the drawings

[0020] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0021] [Fig.1] is a perspective view schematically illustrating an example of a system integrating a photovoltaic module;

[0022] [Fig.2] schematically represents, in block form, an example of a temperature measurement system according to one embodiment;

[0023] [Fig.3] schematically represents, in block form, an example of a method for determining a temperature according to one embodiment;

[0024] Figure 4 schematically represents, in block form, an example of a method for estimating a nighttime temperature according to one embodiment; and

[0025] Figure 5 is a graph schematically illustrating the evolution of an actual nighttime temperature and an estimated nighttime temperature according to one embodiment. Description of embodiments

[0026] The same elements have been designated by the same reference numerals in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0027] For the sake of clarity, only the steps and elements necessary for understanding the described embodiments have been shown and detailed. In particular, the control and processing circuits adapted to implement the described processes have not been detailed, as the construction of such circuits is within the capabilities of a person skilled in the art, based on the information provided in this description. Furthermore, the construction of the modules The photovoltaic systems described have not been detailed, as the described embodiments are compatible with all or most known photovoltaic modules.

[0028] Unless otherwise specified, when reference is made to two interconnected elements, this means directly connected without any intermediate elements other than conductors, and when reference is made to two coupled elements, this means that these two elements can be connected or linked via one or more other elements.

[0029] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0030] Unless otherwise specified, the expressions "approximately", "roughly", and "in the order of" mean within 10%, preferably within 5%.

[0031] Fig. 1 is a perspective view schematically illustrating an example of a system 100 integrating a photovoltaic module.

[0032] In this example, system 100 is a motorized blackout device of the roller shutter type.

[0033] The device 100 includes an apron 102 made up of an assembly of several blades, and further includes a motorized shaft (not visible on [Fig.1]) on which the apron 102 can be wound and from which the apron 102 can be unwound.

[0034] The device 100 further comprises a photovoltaic generator or photovoltaic module 104, comprising one or more photovoltaic panels. By way of example, the device 100 comprises a housing 106 in which the motorized shaft is located. The photovoltaic panel(s) of the photovoltaic module 104 are, for example, arranged on the housing 106.

[0035] The device 100 further includes an electric battery 108 supplied with electrical energy by the photovoltaic module 104 and supplying electrical energy to the device 100, and in particular to the drive motor (not visible on [Fig.1]) of the winding shaft of the curtain 102. By way of example, the battery 108 is disposed in the box 106.

[0036] The device 100 further comprises an electronic control device 110, which allows, in particular, the control of the device's motor. By way of example, the control device 110 is located inside the housing 106.

[0037] The electronic control device 110 may include various sensors, as well as an electronic circuit for processing the data measured by the sensors. By way of example, the electronic processing circuit includes a microcontroller-type processing unit, and may further include one or more memory circuits.

[0038] The occlusion device 100 is intended to be mounted in front of an opening (not visible on [Fig.1]) of a building, capable of letting light through, for example in front of a window fitted with a transparent pane.

[0039] In this example, the electronic control device 110 is configured to implement an automatic, so-called intelligent, control method for the shading device, taking into account, in particular, solar irradiation and the outside temperature. Such a method makes it possible to manage solar heat gain in the building, for example by prioritizing the opening of sun-facing shutters when outside temperatures are low, and / or closing sun-facing shutters when outside temperatures are high.

[0040] Solar irradiation can be estimated by the electronic control device 110 by measuring the short-circuit current of the photovoltaic module 104.

[0041] The outside temperature can be measured using a temperature probe. However, forecasting such a probe entails an additional cost. Furthermore, integrating such a probe into the device 100 may present technical difficulties.

[0042] According to one aspect of an embodiment, the photovoltaic module 104 is planned to be used to estimate the temperature.

[0043] To this end, during phases of solar irradiation of the photovoltaic module, typically during the day, the control device 110 is configured to, during a temperature measurement phase, measure the open-circuit voltage Voc of the photovoltaic module 104 and measure the short-circuit current Isc of the photovoltaic module 104, and then calculate a value Ta representative of the ambient temperature in the vicinity of the photovoltaic module 104, as a function of the measured open-circuit voltage Voc and short-circuit current Isc. More particularly, the value Ta can be calculated using a mathematical model taking as input the measured Isc and Voc values, for example as described in the aforementioned French patent applications No. FR2009735, No. FR2201446 and No. FR2306348.

[0044] The voltage Voc and the current Isc can be measured respectively by a voltage sensor and by a current sensor of the electronic control device 110. The control device 110 can also include controllable switches to put the photovoltaic module in open circuit when measuring the voltage Voc and in short circuit when measuring the current Isc.

[0045] The short-circuit current Isc is, for example, determined by measuring a voltage across a shunt resistor connected to the terminals of the photovoltaic module. The shunt resistor used for measuring the short-circuit current Isc is preferably relatively low in order to obtain an accurate measurement. For example, the shunt resistance is such that the voltage drop across the shunt resistor during the measurement of the current Isc does not exceed 5%, and is preferably on the order of 1% of the open-circuit voltage Voc of the module. For example, for a photovoltaic module with an open-circuit voltage Voc of approximately 7.5 V and a short-circuit current Isc of approximately 0.75 A, a shunt resistance of approximately 0.1 ohms can be used (leading to a voltage drop across the shunt resistor of approximately 0.075 V, or 1% of the open-circuit voltage Voe).

[0046] By ambient temperature, we mean here the temperature of the outside ambient air, that is to say the air outside the module, in the vicinity of the module, for example at a distance of 1 to 30 cm from the module, for example at a distance of 1 to 10 cm from the module.

[0047] By way of example, the value Ta representing the ambient temperature is calculated using a mathematical model of the type described in the aforementioned French patent application FR2306348, i.e. directly from a measurement of the open circuit voltage Voc and the short circuit current Isc of the module, using for this purpose a unique mathematical model with two input variables Voc and Isc, the model having fixed coefficients that can be determined without data on the use of the module or with only a limited amount of data on the use of the module.

[0048] The model describes, for example, the operation of the photovoltaic module using an equivalent diode. One of the model's fixed coefficients is defined, for example, as a function of an ideality factor of the model's equivalent diode, for example, by a linear function of the ideality factor of the photovoltaic module's equivalent diode. The other fixed coefficients of the model are, for example, independent of the photovoltaic module's characteristics.

[0049] This makes it easier to calibrate the model, since it is sufficient to know the ideality factor of the equivalent diode of the photovoltaic module to define the fixed coefficients of the model.

[0050] The ideality factor of the photovoltaic module's equivalent diode, in electron volts (eV), can be provided directly by the photovoltaic module manufacturer, or determined by relatively simple measurements, for example, from two measurements of the I(V) characteristic of the photovoltaic module at two different irradiation levels. As an example, the ideality factor of the photovoltaic module's equivalent diode can be determined as described in the article entitled "Improvement and validation of a model for photovoltaic array performance" by W. De Soto et al. (Solar Energy, Vol. 80, pp. 78-88, 2006).

[0051] By way of example, the mathematical model is defined by the following equation:

[0052] [Math.l] T a (I sc , Voc) = ^ Voc + bx ln(l sr ) + cx I sc + d + e where a, b, c, d and e are the fixed coefficients of the model.

[0053] The coefficients a, b, c, and d are independent of the physical parameters of the photovoltaic module. The fixed coefficient e, on the other hand, depends solely on the ideality factor of the diode and is defined as a linear function of the ideality factor. The fixed coefficients a, b, c, d, and e of the model can be stored in a memory circuit of the electronic control device 110. The coefficient e is, for example, determined during a calibration phase at the system design stage, for instance, by means of a calibration chamber that allows for controlled variation of the irradiation to measure the ideality factor of the diode equivalent to the photovoltaic module. Alternatively, the coefficient e can be determined automatically by the electronic control circuit 110 using any known method for determining the ideality factor of the diode equivalent to a photovoltaic module.

[0054] The method described above makes it possible to accurately estimate the ambient temperature Ta, based on a measurement of the module's short-circuit current Isc and a measurement of the module's open-circuit voltage Voc, through a simple calculation requiring limited computing resources and easily implemented by an embedded electronic control circuit of the system integrating the photovoltaic module. This eliminates the need for a dedicated external temperature probe for this measurement.

[0055] Advantageously, the mathematical model implemented in the process described above can easily be adapted to different types of photovoltaic modules, without requiring a complete characterization of the module over the entire range of ambient temperature and irradiation to which the module is likely to be subjected.

[0056] As an alternative, the temperature Ta is calculated using a mathematical model of the type described in the aforementioned patent application FR2009735, the model having coefficients that can be determined from a measurement of the short-circuit current Isc of the photovoltaic module 104 and the characteristic of the photovoltaic module 104.

[0057] The ambient temperature Ta is, for example, determined by the following equation:

[0058] [Math.2] Ta = a* V oc4-b where a and b are coefficients varying according to solar irradiation calculated by a polynomial relation of order, for example of order 2, as a function of the measurement of the short-circuit current Isc, the coefficients of the polynomial function being determined from the characteristics of the photovoltaic module 104.

[0059] In another variant, the temperature Ta is calculated using a mathematical model of the type described in the aforementioned French patent application FR2201446, directly from a measurement of the open circuit voltage Voc and the short circuit current Isc of the photovoltaic module, using for this purpose a unique polynomial mathematical model with two input variables Voc and Isc.

[0060] The fixed coefficients of the polynomial model are determined during a calibration phase, at the design of the system, by multiple polynomial regression from empirically measured data, and stored in a memory circuit of the electronic control device of the system.

[0061] For example, during the calibration phase, the system can be installed in a calibration chamber allowing the ambient temperature Ta and the irradiation to be varied. The range of ambient temperature Ta values ​​to which the module is likely to be subjected under real operating conditions is then scanned. For each ambient temperature Ta value, the irradiation is varied to scan the range of irradiations to which the module is likely to be subjected under real operating conditions. For each irradiation value and for each ambient temperature Ta value, the short-circuit current Isc and the open-circuit voltage Voc are measured. The fixed coefficients of the model are then determined by multiple polynomial regression from the measurements taken.

[0062] More generally, any other mathematical model allowing the estimation of the ambient temperature from the measurements of the short-circuit current Isc and the open-circuit voltage Voc of the module can be used to calculate the value Ta during periods of solar irradiation of the module.

[0063] Figure 2 schematically represents, in block form, an example of a temperature measurement system 100 according to one embodiment. The system 100 of Figure 2 may be a system of the type described in relation to Figure 1, or, more generally, any system incorporating a photovoltaic module 104. The system 100 comprises an electronic control device 110 connected to the photovoltaic module 104 and adapted to measure the open-circuit voltage Voc and the short-circuit current Isc of the module. The electronic control device 110 is further connected to an electrically controllable element 102 of the system. The electronic device 110 is configured to estimate the ambient temperature Ta in the vicinity of the photovoltaic module 104 from the voltage Voc and the current Isc using a mathematical model, for example of the type described in the aforementioned patent applications, and to control the element 102 accordingly.

[0064] Fig. 3 schematically represents, in block form, an example of a method 300 for measuring the ambient temperature Ta, implemented by the electronic control device 110 in a system of the type described in relation to Fig. 2.

[0065] The method comprises a step 301 (“MEAS Voc”) for measuring the open-circuit voltage Voc of module 104, followed by a step 303 (“MEAS Isc”) for measuring the short-circuit current Isc of the module. In practice, the order of steps 301 and 303 can be reversed. Preferably, steps 301 for measuring the open-circuit voltage Voc of module 104 and 303 for measuring the short-circuit current Isc of the module are carried out within a short time interval, for example, less than one minute apart, in order to maintain substantially identical temperature and irradiation conditions during both measurements.

[0066] The method further comprises, after steps 301 and 303, a step 305 (“CALC Ta(Voc, Isc)”) of calculating the ambient temperature Ta in the vicinity of the module from the voltage Voc and the current Isc, by means of a mathematical model, for example as described in the aforementioned patent applications.

[0067] The process further includes, after step 305, a step 307 (“CTRL”) of checking an element 102 of the system taking into account the ambient temperature Ta calculated in step 305.

[0068] The process 300 is for example implemented by the electronic control device 110 during a daytime use phase of the system.

[0069] A limitation of the methods and systems described above is that they do not allow the ambient temperature to be determined when the photovoltaic module does not receive or does not receive enough solar radiation, and in particular during the night.

[0070] More particularly, the processes and systems described above make it possible to determine the ambient temperature only during daytime use phases of the system.

[0071] By daytime use phase, we mean here a time interval during which the photovoltaic module 104 receives sufficient direct and / or diffuse solar radiation for the measured open-circuit voltage Voc and open-circuit current Isc to be consistent with a change in ambient temperature. The daytime use phase is, for example, delimited by and includes the period between dawn and dusk of a day. Dawn and dusk of a day are, for example, determined respectively by a first threshold V1 and a second threshold V2 of the open-circuit voltage Voc of the photovoltaic module. By way of example, the open-circuit voltage Voc of the module: - is lower than the thresholds V1 and V2 during the night; - grows at sunrise until it crosses threshold VI at dawn; - is above thresholds VI and V2 during the day; and - decreases at sunset until it becomes below the V2 threshold at dusk.

[0072] During the night, the open circuit voltage Voc is for example between 0% and 5% of its nominal value (i.e. the value announced by the manufacturer for normal use of the module during the day).

[0073] The open circuit voltage Voc is for example between 80% and 110% of its nominal value during the day.

[0074] By way of example, the voltage thresholds VI and V2 are between 5 and 25%, for example between 10% and 15%, of the nominal value. For example, the voltage thresholds VI and V2 are equal.

[0075] During nighttime use phases of the system (outside of daytime use phases), the measurements of the short-circuit current Isc and the open-circuit voltage Voc of the module do not allow the ambient outside temperature to be estimated.

[0076] By nighttime use phase, we mean here a time interval during which the photovoltaic module 104 receives relatively low levels of direct and / or diffuse radiation. The nighttime temperature measurement phase, for example, is delimited by and includes the period between dusk of one day and dawn of the following day.

[0077] According to one aspect of an embodiment, the evolution of the nighttime ambient temperature is extrapolated from two values, Tai and Ta2, representing respectively the ambient temperature near dawn on the day immediately preceding the nighttime use phase considered and near dusk on the day immediately preceding the nighttime use phase considered. The Tai and Ta2 values ​​are calculated from measurements of the short-circuit current Isc and the open-circuit voltage Voc of the module during a daytime use phase, during the day immediately preceding the nighttime use phase considered.

[0078] More particularly, according to one aspect of an embodiment, it is planned to calculate a value Ta' representing the estimated nighttime ambient temperature in the vicinity of the photovoltaic module, from the values ​​Tai and Ta2, using a predefined mathematical model or a predefined mathematical function representing the typical nighttime evolution of the outside temperature from dusk of one day until dawn of the following day.

[0079] Fig. 4 schematically represents, in block form, an example of a method 400 for calculating a value Ta' representative of the nighttime ambient temperature according to an embodiment, implemented by the electronic control device 110 in a system of the type described in relation to Fig. 2.

[0080] The method comprises a step 401 (“CALC Tal”) for determining a Tai value representative of the temperature near dawn on the day immediately preceding the nighttime use phase considered, and a step 403 (“CALC Ta2”) for determining a Ta2 value representative of the temperature near dusk on the day immediately preceding the nighttime use phase considered. In the example shown, step 403 is subsequent to step 401. As an alternative, the order of steps 401 and 403 can be reversed.

[0081] The dawn temperatures Tai and dusk temperatures Ta2 are determined from measurements of the short-circuit current Isc and the open-circuit voltage Voc during the daytime use phase preceding the nighttime use phase considered, according to a method of the type described in relation to [Fig.3].

[0082] By way of example, steps 301, 303, and 305 of process 300 in [Fig. 3] are repeated at regular intervals, for example, every 1 to 30 minutes, or every 1 to 10 minutes, throughout the day preceding the nighttime use phase under consideration, so as to obtain a set of ambient temperature values ​​Ta representative of the evolution of the ambient temperature during the day. The ambient temperature values ​​Ta of the day are, for example, stored in a memory circuit and are used to calculate the values ​​Tai and Ta2 during steps 401 and 402 of process 400.

[0083] By way of example, the dawn temperature Ta i corresponds to the first ambient temperature value Ta calculated during the previous daytime temperature measurement phase, after the open circuit voltage Voc crossed the threshold VI.

[0084] As an alternative, the dawn temperature Tai is calculated from several ambient temperature values ​​Ta determined in the vicinity of dawn during the daytime temperature measurement phase preceding the nighttime use phase considered. For example, the temperature Ta i is calculated by averaging the first M ambient temperature values ​​Ta calculated after the open-circuit voltage Voc crosses the threshold VI, with M being an integer strictly greater than 1, for example between 2 and 10, for example equal to 5.

[0085] As an alternative, the dawn temperature Tai is calculated by averaging all the ambient temperature values ​​Ta calculated after the open circuit voltage Voc has crossed the threshold V1, for a predefined period, for example between 5 and 30 minutes.

[0086] As an example, the twilight temperature Ta 2 corresponds to the last ambient temperature value Ta calculated during the previous daytime temperature measurement phase, before the open circuit voltage Voc crossed the threshold V2.

[0087] As an alternative, the twilight temperature Ta 2 is calculated from several ambient temperature values ​​Ta determined in the vicinity of twilight during the daytime temperature measurement phase preceding the nighttime use phase considered. For example, the temperature Ta 2 is calculated by averaging the last N ambient temperature values ​​Ta calculated before the open-circuit voltage Voc crossed the threshold V2, with N being an integer strictly greater than 1, for example between 2 and 10, for example equal to 5.

[0088] As an alternative, the twilight temperature Ta 2 is calculated by averaging all the ambient temperature values ​​Ta calculated before the open circuit voltage Voc crosses the threshold V2, during a predefined period, for example between 5 and 30 minutes.

[0089] The dawn temperature Ta i and the twilight temperature Ta 2 are for example stored in a memory circuit of the electronic control device 110 of the system.

[0090] The process 400 further includes, after steps 401 and 403, a step 405 (“ESTIM Ta'(h,Tal,Ta2)”) of estimating the ambient night temperature Ta' in the vicinity of the module from the temperature Ta i and the temperature Ta 2.

[0091] For this purpose, a predefined mathematical function the electronic control and processing device 110 implements a predefined mathematical function or a predefined mathematical model representative of the typical evolution of the night temperature between a given twilight value and a given dawn value.

[0092] Step 405 can be implemented at any time during the nighttime use phase under consideration. At that time, only the temperature Ta2 near dusk, marking the beginning of the night under consideration, is known. Since the temperature near dawn, marking the end of the night under consideration, is not yet known, the temperature Tai near dawn of the previous day is used, as an approximation, to model the evolution of the ambient nighttime temperature.

[0093] By way of example, the mathematical function used to estimate the evolution of the ambient night temperature is a linear function defined as follows:

[0094] [Math.3] T a (h, Tal, Ta2) = Ta2+^ x(Tal-Ta2) where h is a time variable representing the time at which the ambient night temperature Ta' is estimated, hl corresponds to the time of dawn of the previous day (in the vicinity of which the temperature Tai was estimated) and h2 corresponds to the time of dusk of the previous day (in the vicinity of which the temperature Ta2 was estimated).

[0095] The use of a linear function has the advantage of limiting the computational resources required to estimate the ambient night temperature Ta'. However, such a function does not accurately represent the evolution of the ambient temperature during the night and generally tends to overestimate the night temperature, the characteristic evolution of which is generally exponential.

[0096] Thus, as an alternative, the mathematical function used to estimate the evolution of the ambient night temperature is an exponential relaxation function defined as follows:

[0097] [Math.4] T a (h, Tal, Ta2) = Tal+(Ta2-Tal)xexp(-ax (h-h2)) where a corresponds to a relaxation parameter. The parameter a is, for example, stored in a memory of the electronic control device 110 of the system.

[0098] More generally, any other mathematical function representing the typical evolution of nighttime temperature in the environment of use considered may be used, for example a Gaussian function, a polynomial function, a spline function, for example cubic, etc.

[0099] In step 405, the ambient night temperature Ta' can be calculated for one or more time intervals h during the night in question. For example, the ambient night temperature Ta' can be estimated for a set of time intervals h regularly distributed throughout the night in question, so as to reconstruct a curve representing the evolution of the ambient night temperature during the night. As an example, the time interval separating two consecutive estimated ambient night temperature values ​​Ta' is between 1 and 30 minutes, for example, between 1 and 10 minutes.

[0100] The process further includes, after step 405, a step 407 (“CTRL”) of checking an element 102 of the system by the electronic control device 110, taking into account at least one value of the night ambient temperature Ta' calculated in step 405.

[0101] By way of example, in the case of a system of the type described in relation to [Fig.1], in step 407, during periods of high heat, the electronic control device 110 controls the opening of the motorized roller shutter in a so-called ventilation state, allowing outside air to enter the building, from a time h at which the estimated nighttime ambient temperature Ta' falls below a predefined temperature threshold.

[0102] As an alternative, during periods of lower heat, the electronic control device 110 controls the closing of the motorized roller shutter, preventing outside air from entering the building, from a time h at which the estimated nighttime ambient temperature Ta' falls below a predefined temperature threshold.

[0103] More generally, the aforementioned method for estimating the evolution of the night ambient temperature Ta' can be used for any other application, for example to control a heating device from a time h when the estimated night ambient temperature Ta' falls below a predefined temperature threshold, or to control an air conditioning device from a time h when the estimated night ambient temperature Ta' falls above a predefined temperature threshold.

[0104] A system of the type described in relation to [Fig. 1] or 2 may further include a temperature probe (not shown), for example positioned near a motor or electrochemical cells of a battery in the system, to implement control and safety functions. Such a probe is generally not suitable for measuring ambient temperature in the vicinity of the photovoltaic module, due to the significant thermal inertia of the housing in which it is located, or because the elements controlled by this probe (motor, battery, etc.) generally have a temperature different from the outside ambient temperature.

[0105] During nighttime use of the system, and especially at the end of the night, the temperature measured by such a probe may, however, approach the ambient outside temperature of the system.

[0106] Such a probe can thus be used to detect any possible difference between the actual nighttime ambient temperature and the nighttime ambient temperature Ta' estimated in step 405.

[0107] By way of example, the process 400 includes, after step 405 and before step 407, a step (not shown) for verifying the consistency between the estimated nighttime ambient temperature Ta' in step 405 and an actual temperature measured by a sensor internal to the system. For example, if the actual temperature measured by the internal sensor is lower than the estimated ambient temperature Ta', the actual measured temperature will be used for the implementation of control step 407. Otherwise, the estimated temperature Ta' will be used for the implementation of control step 407.

[0108] The [Fig.5] is a diagram schematically illustrating the evolution, as a function of time h (on the abscissa) of the outside ambient temperature T (on the ordinate) in a system of the type described above, over a period of 48 hours comprising two days and two nights.

[0109] Time hl corresponds to dawn on the first day. Time h2 corresponds to dusk on the first day. Time hl' corresponds to dawn on the second day. Time h2' corresponds to dusk on the second day. Time hl” corresponds to dawn on the third day (end of the second night).

[0110] In the example of [Fig.5], the two shaded areas 502 correspond to the two phases of night temperature measurement, delimited respectively by the times h2 and hl' and by the times h2' and hl”.

[0111] During the daytime temperature measurement phases, i.e. between times hl and h2 on the one hand, and between times hl' and h2' on the other hand, the ambient temperature Ta is calculated, for example by the method 300 described in relation to [Fig.3].

[0112] A curve 516 represents the evolution of the temperature Ta as a function of time between during the phases of diurnal temperature measurement.

[0113] By way of example, the ambient temperature Ta is calculated at regular intervals, for example every 1 to 30 minutes throughout the daytime temperature measurement phases.

[0114] The first ambient temperature(s) Ta, referenced 504, and the last ambient temperature(s) Ta, referenced 506, calculated during the first phase of daytime temperature measurement, are recorded in a memory circuit of the system.

[0115] For the first phase of nighttime temperature measurement, i.e. between times h2 and hl', the set of values ​​representative of the ambient nighttime temperature Ta' is calculated, for example by the method 400 described in relation to [Fig. 4]. The temperature(s) 504 are used for the calculation of the dawn temperature Ta[ and the temperature(s) 506 are used for the calculation of the dusk temperature T^.

[0116] Similarly, during the second phase of daytime temperature measurement, the first ambient temperature(s) Ta, referenced 508, and the last ambient temperature(s) Ta, referenced 510, are recorded in a memory circuit of the system.

[0117] During the second phase of nighttime temperature measurement, i.e., between times h2' and hl”, the representative set of values ​​for the ambient nighttime temperature Ta' is calculated, for example by method 400 described in relation to [Fig. 4]. The temperature(s) 508 are used for the calculation of the dawn temperature Ta[ and the temperature(s) 510 are used for the calculation of the dusk temperature T^.

[0118] A curve 512 illustrating the actual nighttime ambient temperature and a curve 514 illustrating the estimated nighttime ambient temperature Ta' are shown in [Fig.5].

[0119] On [Fig.5], a horizontal line 518 has been shown, illustrating a nighttime heatwave threshold above which, according to one example of operation, the electronic control device 110 keeps the motorized roller shutter in the closed position, and below which, in said example of operation, the electronic control device 110 commands the motorized roller shutter to open ventilation position, for example in raised position or in lowered position with an orientation of the blades constituting the apron allowing air circulation.

[0120] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to those skilled in the art. In particular, the described embodiments are not limited to the application examples explicitly mentioned above, but can be adapted to any system incorporating a photovoltaic module and in which an ambient temperature measurement in the vicinity of the photovoltaic module can be used.

[0121] Furthermore, the described embodiments are not limited to the aforementioned application to a motorized roller shutter system. More generally, the proposed solution can be applied to any system comprising a photovoltaic module, in which it is desired to be able to measure the ambient temperature in the vicinity of the module. For example, the photovoltaic module can be installed on the roof of a building. The ambient temperature in the vicinity of the module can, for example, be used by an electronic control device to automatically control a heating or cooling system for the building, or simply transmitted to the user via an electronic display device for informational purposes.

[0122] Finally, the practical implementation of the embodiments and variants described is within the reach of a person skilled in the art, based on the functional indications given above.

Claims

Demands

1. Method for determining a nighttime ambient outdoor temperature Ta' in a system comprising a photovoltaic module (104), the method comprising the following steps: a) determining, by means of an electronic processing device (110), from measurements of the short-circuit current Isc and measurements of the open-circuit voltage Voc of the photovoltaic module (104), a first value Tai representative of the ambient outdoor temperature in the vicinity of dawn of a first day and a second value Ta2 representative of the ambient outdoor temperature in the vicinity of dusk of the first day;and b) calculate, using the electronic processing device (110), from the first value Tai and the second value Ta2 determined in step a), using a predefined mathematical function Ta', a set of one or more values ​​representative of the evolution of the ambient nighttime outside temperature during the night following said first day.;

2. Method according to claim 1, wherein the mathematical function Ta' is a linear, Gaussian, polynomial, spline, or exponential relaxation function.

3. Method according to claim 2, wherein the mathematical function Ta' is an exponential relaxation function defined by the following relation: [Math.4] Ta(h, Tal, Ta2) = Tal+(Ta2-Tal)xex^-ax (h-h2)} where h is a time variable, a is a relaxation parameter and h2 is an instant corresponding to twilight of the first day.

4. Method according to claim 3, wherein the relaxation parameter a is stored in a memory of the electronic processing device (110).

5. A method according to any one of claims 1 to 4, wherein the first Tai value is determined from one or more daytime ambient temperature values, each daytime ambient temperature value being calculated from a measurement of the short-circuit current Isc and a measurement of the voltage open circuit Voc of the photovoltaic module (104) carried out in the vicinity of the dawn.

6. A method according to any one of claims 1 to 5, wherein the second value Ta2 is determined from one or more daytime ambient temperature values, each daytime ambient temperature value being calculated from a measurement of the short-circuit current Isc and a measurement of the open-circuit voltage Voc of the photovoltaic module (104) carried out in the vicinity of dusk.

7. A method according to any one of claims 1 to 6, wherein, in step a), the value of the short-circuit current Isc of the photovoltaic module is determined by measuring a voltage across a shunt resistor connected to the terminals of the photovoltaic module (104).

8. A method according to claim 7, wherein the value of the shunt resistance is such that the voltage across the shunt resistance when measuring the short-circuit current Isc of the photovoltaic module (104) is less than 5% of the open-circuit voltage Voc of the photovoltaic module (104).

9. A method according to any one of claims 1 to 8, further comprising a step of controlling an electrically controllable element (102) of the system taking into account at least one value of the night ambient temperature calculated in step b).

10. System (100) comprising a photovoltaic module (104) and an electronic processing device (110) configured to implement a method according to any one of claims 1 to 9.

11. System (100) according to claim 10, comprising a motorized shading device powered by the photovoltaic module (104).

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