Monitoring procedure and monitoring arrangement for a solar module arrangement of a vehicle

Abstract

The invention relates to a monitoring method for a solar module arrangement (14) with at least two solar modules 16 arranged on the outer skin of a vehicle (1) and an identical reference solar module 18 arranged in the area of ​​effect of a windshield cleaning system of a windshield 3. Here, solar irradiance conditions and the position of the solar modules (16) and the reference solar module (18) relative to the sun are continuously determined, the reference solar module (18) is cleaned, and the electrical power output of the reference solar module (18) and the solar modules (16) is recorded. Based on the electrical power output of the reference solar module (18), the solar irradiance conditions, and the position of the reference solar module (18) relative to the sun, a realistically possible electrical power output is determined and stored as a reference value.wherein, in real time, based on the reference value, the current solar irradiance conditions, and the current position of the solar modules (16) relative to the sun, a theoretically possible electrical power output of the individual solar modules (16) is determined and compared with the actual electrical power output, wherein a soiling (26) of at least one solar module (16) is inferred if a difference between the theoretically possible and the actual electrical power output of the corresponding solar module (16) exceeds a threshold value.

Description

The invention relates to a monitoring method for a solar module arrangement with at least two solar modules arranged on the outer skin of a vehicle. Furthermore, the invention relates to a monitoring arrangement for a solar module arrangement of a vehicle, which is configured to carry out such a monitoring method. Monitoring methods and systems for vehicle solar panel arrays exist in numerous variations. Solar panels on vehicles are becoming increasingly important, particularly for supporting on-board electronics or partially relieving the load on the traction battery. The efficiency of these solar panels depends significantly on the amount of sunlight that reaches the photovoltaic cells unimpeded. A clean surface ensures maximum light transmission and thus optimal energy conversion. While the performance of modern solar modules is constantly increasing thanks to improvements in materials research and manufacturing technology, the availability of a consistently clean surface remains a crucial factor for a constant energy yield. However, solar modules are exposed to various environmental influences during vehicle operation. Driving, as well as external factors such as wind, weather, and road conditions, cause various particles and substances to accumulate on the surface of the solar modules. These deposits can consist of, for example, dust, pollen, insect residue, water films, oily road abrasion, or industrial air pollutants. The effect of such deposits on light transmission occurs in various ways. Fine dust particles reduce the overall transmission of light by partially absorbing and scattering it. Organic substances, such as pollen, contain natural pigments that selectively absorb certain wavelengths. Moisture and water films alter the refraction of light, while oily residues attenuate the incident light across a broad spectrum. Current methods for assessing soiling, such as optical cameras or performance comparison measurements, are inaccurate and inefficient. Cleaning systems in vehicles often operate at fixed intervals, leading to unnecessary energy consumption and resource waste. Furthermore, frequent or unnecessary cleaning puts mechanical and chemical stress on the solar modules, reducing their efficiency in the long term. Currently, methods for assessing solar module soiling are often based on indirect techniques such as performance comparison measurements or optical inspections. While monitoring systems can detect power losses, these methods do not provide detailed information about the type or cause of the soiling. Optical outdoor cameras, on the other hand, are susceptible to changing lighting conditions and perspective distortions. Without a reliable monitoring system, solar module soiling often goes undetected, leading to power losses. Cleaning typically only occurs after a significant drop in efficiency or during a chance inspection. German patent DE 10 2019 001 571 A1 discloses a surface cleaning device for a solar module or solar panel, comprising vibrating elements and sensors capable of determining the degree of soiling on the solar module's surface. As soon as soiling is detected, an evaluation unit activates the vibrating elements. This allows the solar module to clean or dust itself. The solar module or solar panel can also have a dirt-repellent and water-repellent coating. The self-cleaning process is automatically controlled by dirt sensors. An entire solar power system with thousands of solar modules can be cleaned of dust within seconds. Another variant of the solar module is coupled with a circuit that briefly and automatically heats the solar module when sensors detect snow or ice on its surface.A variant with compressed air nozzles for dusting the solar modules is also planned. From JP 2016-158 446 A, a monitoring unit for a solar cell module is known which is capable of efficiently detecting dirt on the surface of the solar cell module. The monitoring unit of the solar cell module comprises an estimating part, a sensing part, and a determination part. The estimating part determines an estimated value of the amount of electrical energy generated by the solar cell module based on the amount of solar irradiance and the temperature. The sensing part detects a measured value of the amount of electrical power generated by the solar cell module. If the estimated value exceeds the measured value, the determination part detects that the surface of the solar cell module is dirty. From KR 10 2016 0 069 760 A, a vehicle is known with a cluster comprising a solar cell that converts solar energy into electrical energy, a light quantity detection unit that measures the amount of light incident on the solar cell, a power generation quantity detection unit that measures the amount of power generated by the solar cell, and a control unit that monitors the state of the solar cell based on the detected power generation and light quantity and controls the monitoring information of the solar cell to be displayed on the cluster. The cluster displays the monitoring information for the solar cell's state in real time, enabling a user to easily identify abnormal conditions of the solar cell and the improvements in fuel efficiency resulting from its use. US Patent 2013 / 0159064 A1 discloses a monitoring method for a solar module arrangement comprising at least two solar modules, an ambient photovoltaic panel, and an identical reference solar module. In this method, the reference solar module is cleaned, and the current electrical power output of both the cleaned reference solar module and the ambient photovoltaic panel is recorded. Based on the current electrical power output of the reference solar module and the ambient photovoltaic panel, a conclusion is drawn regarding the soiling of at least one of the at least two solar modules. The invention is based on the objective of providing a monitoring method for a solar module arrangement of a vehicle and a corresponding monitoring arrangement for carrying out the method, which reliably, efficiently and resource-efficiently detects contamination of solar modules arranged on an outer skin of the vehicle. This problem is solved by a monitoring method for a solar module arrangement of a vehicle with the features of claim 1 and by a monitoring arrangement for a solar module arrangement of a vehicle with the features of claim 8. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims. To provide a monitoring method for a vehicle's solar panel array that reliably, efficiently, and resource-conservingly detects soiling of solar panels mounted on the vehicle's exterior, an identical reference solar panel is positioned within the operating range of a windshield washer system. Current solar irradiance conditions and the current position of at least two solar panels and the reference solar panel relative to the sun are continuously determined. The reference solar panel is cleaned, and the current electrical power output of both the cleaned reference solar panel and the at least two solar panels is recorded.Based on the current electrical power output of the reference solar module, the current solar irradiance conditions, and the current orientation of the cleaned reference solar module relative to the sun, a realistically possible electrical power output of the reference solar module is determined and stored as a reference value. Based on this stored reference value, the current solar irradiance conditions, and the respective current orientation of at least two solar modules relative to the sun, a theoretically possible electrical power output of each individual solar module is determined in real time and compared with the actual electrical power output of each module. Soiling of at least one of the at least two solar modules is inferred if the difference between the theoretically possible electrical power output and the actual electrical power output of the corresponding solar module exceeds a predefined threshold. Furthermore, a monitoring arrangement is proposed for a solar module array comprising at least two solar modules mounted on the outer skin of a vehicle and an identical reference solar module positioned within the effective range of a windshield cleaning system. This arrangement is designed to execute such a monitoring procedure. For this purpose, at least one sensor unit, an information system with an optical display unit, and an evaluation and control unit are provided. The core of the invention consists of permanently arranging, preferably integrating, a dedicated solar module as a reference solar module in the lower area of ​​the windshield, thus enabling regular cleaning via existing mechanisms such as windshield wipers and spray nozzles. Due to this targeted cleaning capability, a soiling level of "zero" can be assumed for the reference solar module. The reference module has identical cell technology to the other sensor modules and is equipped with sensors for measuring current, voltage, and temperature in order to provide valid reference values ​​under the current environmental conditions. It functions as a reliable reference source for the maximum achievable power output or energy yield under given solar and environmental conditions.The solar module array continuously records the electrical power output of all solar modules and simultaneously captures intensity- and spectral-dependent irradiance conditions, vehicle orientation, geoposition, and the geometric parameters of all solar module surfaces, such as azimuth, tilt angle, module size, etc. From this, an individually calculated theoretical power output or energy yield is derived for each solar module, based on a physical model of solar irradiance. The actual power output or energy output can be compared in real time with this calculated ideal value or the theoretical power output or energy yield. Deviations that cannot be explained by systematic differences in orientation, irradiance, alignment, or temperature can be interpreted as an indicator of local surface soiling.The difference between theoretically possible and actually measured power output or energy yield can serve as a basis for the quantitative determination of the degree of pollution of the individual solar modules. Embodiments of the invention enable precise, continuous, and spatially resolved determination of the degree of soiling of solar modules mounted on the vehicle's exterior under real operating conditions, serving both energy optimization and user diagnostic support. By integrating a regularly cleaned reference module in conjunction with computationally considering the respective module orientation to the sun, a reliable derivation of the theoretically possible energy yield or power output is made possible. Performance deviations of individual solar modules can thus be directly attributed to local soiling. Additionally, a spatially resolved visualization of the soil distribution can be provided on a digital vehicle model and displayed in the interior.This supports targeted maintenance planning, improves yield transparency, and creates a physically sound basis for automatic or manual cleaning decisions. In an advantageous embodiment of the monitoring procedure, the detected soiling of at least one of the at least two solar modules can be displayed by an information system in the vehicle. In a further advantageous embodiment of the monitoring procedure, the at least two solar modules can be divided into at least two spatial module clusters to refine the diagnostics. This enables the additional implementation of cluster analysis, allowing spatial soiling patterns to be detected. Here, the power output ratios of the solar modules within each of the at least two spatial module clusters can be evaluated in relation to each other and in comparison to the reference solar module. Based on this evaluation, local power losses can be identified and conclusions can be drawn about soiling gradients. This means that differences in soiling within a specific vehicle area can be detected. In addition to the absolute power losses, their temporal derivatives can also be taken into account.Furthermore, pattern recognition based on the pollution gradients can be used to qualitatively differentiate between several types of pollution. For example, it is possible to distinguish between flat dust layers, such as homogeneous dust accumulation on horizontal surfaces or streak-like deposits along an airflow, and point-like pollution caused by organic material, such as leaves or insect remains. In a further advantageous embodiment of the monitoring method, the detected soiling of at least one of the at least two solar modules can be transferred to a digital model of the vehicle and displayed on an optical display unit. Preferably, the detected soiling can be projected onto a digital 3D model of the vehicle in the form of a virtual dirt layer and displayed in the interior. The 3D model represents the physical vehicle surface and serves as a projection surface for the virtual dirt layer, which can be generated in real time, for example, by interpolating the measurement data over adjacent surfaces. A soiling value can be interpolated for each module surface and visually displayed, for example, using color gradients, transparency patterns, or structured textures. The projection can depict both the intensity and the distribution of the soiling on the vehicle.This enables targeted maintenance planning, improved yield transparency, and the creation of a physically sound basis for automatic or manual cleaning decisions. The optical display unit can be implemented, for example, as a head-up display or a digital instrument cluster. The driver can preferably receive visual indications of soiling areas, including recommendations such as "Soiling zone on left roof half - cleaning recommended," "Reduced performance at the rear due to partial shading," or "Possible permanent deposit - manual inspection required." Preferably, the user can rotate, zoom, or filter the 3D model display by intensity, thus enabling targeted analysis of individual vehicle areas. In an advantageous embodiment of the monitoring arrangement, the at least one sensor unit can be configured to detect current solar irradiance conditions and current electrical power output of the cleaned reference solar module and current electrical power output of the at least two solar modules. In a further advantageous embodiment of the monitoring arrangement, the evaluation and control unit can be configured to continuously determine the current position of the at least two solar modules and the reference solar module relative to the sun, based on the current solar irradiance conditions and the geometric installation position of the at least two solar modules and the reference solar module within the vehicle coordinate system. Each solar module on the vehicle surface or outer skin can be individually detected and its geometric position within the vehicle coordinate system recorded. The current module orientation relative to the sun can preferably be calculated using a combination of GPS data (GPS: Global Positioning System), real-time time data, and vehicle-integrated motion sensors (IMU).Together with the measured solar radiation, which can be determined either directly via a sensor or indirectly via the reference module, an expected power output or a calculated expected energy yield can be determined for each solar module and compared with the actual power output or energy yield. Additionally, optional cleaning mechanisms can be coupled with the monitoring system, which can be selectively activated when certain levels of soiling are exceeded. Furthermore, the integration of historical performance data can allow for a retrospective analysis of energy loss, thus supporting optimized maintenance planning and a predictive operating strategy for photovoltaically equipped vehicles. The features and combinations of features mentioned above in the description, as well as those subsequently mentioned in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments that are not explicitly shown or explained in the figures, but which can be derived and generated from the explained embodiments by separate combinations of features, are also to be considered as encompassed and disclosed by the invention. Exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. In the drawings, identical reference numerals denote components or elements that perform the same or analogous functions. Figure 1 shows a schematic flowchart of an exemplary embodiment of a monitoring method according to the invention for a solar module arrangement of a vehicle; and Figure 2 shows a schematic representation of a vehicle with an exemplary embodiment of a monitoring arrangement according to the invention for a solar module arrangement. As can be seen from Figs. 1 and 2, the illustrated embodiment of a monitoring method 100 according to the invention for a solar module arrangement 14 with at least two solar modules 16 arranged on the outer skin of a vehicle 1 and an identical reference solar module 18 arranged in the area of ​​effect of a windshield cleaning system 3 comprises a step S100 in which current solar irradiance conditions and the current position of the at least two solar modules 16 and the reference solar module 18 relative to the sun are continuously determined. In a step S110, the reference solar module 18 is cleaned, and in a step S120, the current electrical power output of the cleaned reference solar module 18 and the at least two solar modules 16 is recorded.In step S130, based on the current electrical power output of the reference solar module 18, the current solar irradiance conditions, and the current position of the cleaned reference solar module 18 relative to the sun, a realistically possible electrical power output of the reference solar module 18 is determined and stored as a reference value. In step S140, based on the stored reference value, the current solar irradiance conditions, and the respective current position of the at least two solar modules 16 relative to the sun, a theoretically possible electrical power output of each individual solar module 16 is determined in real time and compared in step S150 with the actual electrical power output of each individual solar module 16.In step S160, a soiling 26 of at least one of the at least two solar modules 16 is inferred if, in step S150, a difference between the theoretically possible electrical power output and the actual electrical power output of the corresponding solar module 16 exceeds a predefined threshold. Otherwise, the monitoring procedure 100 returns to step S100. In the illustrated embodiment of the monitoring method 100, in step S170 the detected contamination 26 of the at least one solar module 16 or at least two solar modules 16 is displayed by an information system 20 in the vehicle 1. The monitoring method 100 then returns to step S100. As can be further seen from Fig. 2, the illustrated embodiment of a monitoring arrangement 10 according to the invention for a solar module arrangement 14 with at least two solar modules 16 arranged on an outer skin of a vehicle 1 and an identical reference solar module 18 arranged in the area of ​​effect of a windshield cleaning system of a windshield 3 comprises at least one sensor unit 19, an information system 20 with an optical display unit 22 and an evaluation and control unit 12. The monitoring arrangement 10 is configured to carry out the monitoring method 100 according to the invention. In the illustrated embodiment of the monitoring arrangement 10, the at least one sensor unit 19 is configured to detect current solar irradiance conditions and the current electrical power output of the cleaned reference solar module 18 and the current electrical power output of the at least two solar modules 16. The evaluation and control unit 12 is configured to continuously determine the current position of the at least two solar modules 16 and the reference solar module 18 relative to the sun, based on the current solar irradiance conditions and their geometric installation position in the vehicle coordinate system. To refine the diagnostics, the solar modules 16 in the illustrated embodiments are divided into three spatial module clusters 17. A first spatial module cluster 17A comprises a first solar module 16A and a second solar module 16B, which are arranged on a tailgate of the vehicle 1. A second spatial module cluster 17B comprises a third solar module 16C and a fourth solar module 16D, which are arranged on a roof of the vehicle 1. A third spatial module cluster 17C comprises a fifth solar module 16E and a sixth solar module 16F, which are arranged on a front hood of the vehicle 1. The evaluation and control unit 12 is further designed to evaluate the power output ratios of the solar modules 16 in the three spatial module clusters 17 relative to each other and in comparison to the reference solar module 18. Based on this evaluation, local power losses are detected and conclusions are drawn about soiling gradients.In addition to the absolute power losses, their temporal derivative is also taken into account. The evaluation and control unit 12 calculates the current module orientation to the sun, preferably using a combination of GPS data (GPS: Global Positioning System), real-time time data, and vehicle-integrated position sensors (IMU). Together with the measured solar radiation, which in the illustrated embodiment is determined directly by the sensor unit 19, the evaluation and control unit 12 determines an expected power output or a calculated energy yield for each solar module and compares this with the actual power output or energy yield. In the illustrated embodiments, the evaluation and control unit 12 is further designed to perform pattern recognition based on the pollution gradients for the qualitative differentiation of several types of pollution. Furthermore, the evaluation and control unit 12 is designed to transfer the detected pollution 26 of the at least one solar module 16 of the six solar modules 16 to a digital model, here a digital 3D model 24 of the vehicle 1, and to display it on an optical display unit 22. In the illustrated embodiment of the monitoring arrangement 10, the optical display unit 22 of the information system 20 is designed as a digital instrument cluster 22A. As can be seen in Fig. 2, two contaminants 26 are projected onto the depicted digital 3D model 24 of the vehicle 1. A first contaminant 26A is located on the two solar modules 16 of the third module cluster 17C, which is arranged on the front hood. A second contaminant 26B is located on the two solar modules 16 of the second module cluster 17B, which is arranged on the vehicle roof. REFERENCE MARK LIST 1 Vehicle 3 Windscreen 10 Monitoring arrangement 12 Evaluation and control unit 14 Solar module arrangement 16, 16A, 16B, 16C, 16D, 16E, 16F Solar module 17, 17A, 17B, 17C Module cluster 18 Reference solar module 19 Sensor unit 20 Information system 22 Optical display unit 22A Digital instrument cluster 24 Vehicle model 26, 26A, 26B Contamination 100 Monitoring procedure S100 to S170 Procedure step

Claims

Monitoring method (100) for a solar module arrangement (14) with at least two solar modules 16 arranged on an outer skin of a vehicle 1 and an identical reference solar module 18 arranged in the area of ​​effect of a windshield cleaning system of a windshield 3, wherein current solar irradiance conditions and a current position of the at least two solar modules (16) and the reference solar module (18) to the sun are continuously determined (S100), wherein the reference solar module (18) is cleaned (S110) and a current electrical power output of the cleaned reference solar module (18) and of the at least two solar modules (16) is recorded,wherein, based on the current electrical power output of the reference solar module (18) and the current solar irradiance conditions and the current position of the cleaned reference solar module (18) relative to the sun, a realistically possible electrical power output of the reference solar module (18) is determined and stored as a reference value (S120), wherein, in real time, based on the stored reference value and the current solar irradiance conditions and the respective current position of the at least two solar modules (16) relative to the sun, a theoretically possible electrical power output of the individual solar modules (16) is determined (S130) and compared with the current electrical power output of the individual solar modules (16) (S140), wherein a soiling (26) of at least one solar module (16) of the at least two solar modules (16) is inferred (S150),when a difference between the theoretically possible electrical power output and the actual electrical power output of the corresponding solar module (16) exceeds a predetermined threshold. Monitoring method (100) according to claim 1, characterized in that the detected contamination (26) of the at least one solar module (16) of the at least two solar modules (16) is displayed by an information system (20) in the vehicle (1) (S160). Monitoring method (100) according to claim 1 or 2, characterized in that the at least two solar modules (16) are divided into at least two spatial module clusters (17). Monitoring method (100) according to claim 3, characterized in that the power output ratios of the solar modules (16) in the individual of the at least two spatial module clusters (17) are evaluated in relation to each other and in comparison to the reference solar module (18). Monitoring method (100) according to claim 4, characterized in that local power losses are detected based on the evaluation and conclusions are drawn about pollution gradients, taking into account not only the absolute power losses but also their temporal derivative. Monitoring method (100) according to claim 5, characterized in that pattern recognition is carried out based on the pollution gradients for the qualitative differentiation of several types of pollution. Monitoring method (100) according to claims 2 and 6, characterized in that the detected contamination (26) of the at least one solar module (16) of the at least two solar modules (16) is transferred to a digital model (24) of the vehicle (1) and displayed on an optical display unit (22). Monitoring arrangement (10) for a solar module arrangement (14) with at least two solar modules (16) arranged on an outer skin of a vehicle (1) and an identical reference solar module (18) arranged in the area of ​​effect of a windshield cleaning system of a windshield (3), wherein at least one sensor unit (19), an information system (20) with an optical display unit (22) and an evaluation and control unit (12) are provided and the monitoring arrangement (10) is configured to carry out the monitoring method (100) according to one of claims 1 to 7. Monitoring arrangement (10) according to claim 8, characterized in that the at least one sensor unit (19) is configured to detect current solar irradiance conditions and current electrical power output of the cleaned reference solar module (18) and current electrical power output of the at least two solar modules (16). Monitoring arrangement (10) according to claim 8 or 9, characterized in that the evaluation and control unit (12) is designed to continuously determine the current position of the at least two solar modules (16) and the reference solar module (18) relative to the sun, based on the current solar irradiance conditions and a geometric installation position of the at least two solar modules (16) and the reference solar module (18) in the vehicle coordinate system.

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