Solar system
By measuring the current and voltage values of solar panels and utilizing the differential conductance change and current difference of the IV curve, the accuracy problem of dirt detection in solar energy systems has been solved, achieving efficient and accurate dirt detection and power optimization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2025-11-06
- Publication Date
- 2026-06-05
AI Technical Summary
Existing solar energy systems are susceptible to changes in external factors when determining whether there is dirt on solar panels, leading to decreased accuracy and difficulty in accurately judging the condition of the panels.
By measuring the current and voltage output of the solar panel, the condition of the panel is determined using the differential conductance change on the IV curve. The presence of dirt is also determined by combining the current difference, and the power output is optimized through MPPT control.
It enables accurate determination of the presence and area of dirt on solar panels in a short time, improving the accuracy of condition judgment and optimizing power output efficiency.
Smart Images
Figure CN122159792A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a solar energy system. Background Technology
[0002] Patent Document 1 discloses a solar energy system that uses an IV curve (representing the correlation between current and voltage values output from a solar panel) to determine whether a first-step voltage generated during parking is consistent with a second-step voltage generated during driving. If the first-step voltage is consistent with the second-step voltage, it indicates the presence of an object moving at the same speed as the vehicle, thus suggesting the presence of dirt or similar contaminants on the solar panel.
[0003] Patent Document 1: Japanese Patent Application Publication No. 2017-162171 Summary of the Invention
[0004] Patent Document 1's solar energy system compares the voltage during parking with the voltage during driving. Therefore, when external factors such as solar radiation intensity and solar panel temperature change during parking and driving, the accuracy of determining whether dirt or other contaminants adhere to the solar panel may decrease. Therefore, a technology that can more accurately determine the condition of the solar panel is desired.
[0005] This invention can be implemented in the following ways.
[0006] (1) According to one aspect of the present invention, a solar energy system capable of being mounted on a vehicle is provided. The solar energy system includes: a solar panel; a current sensor that measures a current value output from the solar panel; a voltage sensor that measures a voltage value output from the solar panel; and a control unit that determines the state of the solar panel based on the difference between a first current value and a second current value, wherein the first current value is the current value corresponding to the voltage value at that time, i.e., the first voltage value, when the differential conductance changes from a value above a predetermined first threshold to a value below the first threshold on an IV curve representing the correlation between the current value and the voltage value over a predetermined period; and the second current value is the current value corresponding to the voltage value at that time, i.e., the second voltage value, when the differential conductance changes from a value below the first threshold to a value above the first threshold on the IV curve.
[0007] Based on this method, the condition of solar panels can be determined more accurately.
[0008] (2) In the solar energy system described above, the control unit can determine whether there is dirt on the solar panel based on the difference between the first current value and the second current value.
[0009] According to this method, solar energy systems can more accurately determine whether there is dirt attached to solar panels.
[0010] (3) In the solar energy system described above, the control unit can estimate the area of dirt attached to the solar panel based on the difference between the first current value and the second current value.
[0011] Based on this method of solar energy system, it is possible to estimate the area of dirt adhering to solar panels.
[0012] Based on this method, the condition of the solar panels can be precisely estimated.
[0013] (4) In the solar energy system described above, the control unit can control the notification unit mounted on the vehicle to notify the occupants of the vehicle of the area of dirt attached to the solar panel.
[0014] According to this type of solar energy system, vehicle occupants can determine the area of dirt adhering to the solar panels.
[0015] (5) The control unit can control the power output from the solar panel through maximum power point tracking (MPPT) control, and the IV curve can be obtained during the execution of the MPPT control.
[0016] According to this method, the solar energy system can efficiently determine the state of the solar panels compared to separately determining the state of the solar panels and performing MPPT control. Attached Figure Description
[0017] Figure 1 This is an explanatory diagram showing the structure of a solar energy system.
[0018] Figure 2 This is a graph showing an example of the IV curve when a solar panel is generating electricity normally.
[0019] Figure 3 This is a graph showing an example of the IV curve when the power generation of a portion of the solar cells is reduced.
[0020] Figure 4 This is a flowchart of the estimation process performed by the control department.
[0021] Figure 5 This is a graph showing an example of the IV curve and di / dv-V curve obtained in the estimation process.
[0022] Figure 6This is a graph illustrating the relationship between the difference between the first and second current values and the area of dirt adhering to the solar panel. Detailed Implementation
[0023] A. Implementation Method 1:
[0024] Figure 1 This is an explanatory diagram showing the structure of the solar energy system 100. The solar energy system 100 can be mounted on a mobile vehicle 500. The solar energy system 100 includes a solar panel 10, a current sensor 20, a voltage sensor 30, a DC-DC converter 40, and a control unit 50.
[0025] The solar panel 10 is composed of multiple clusters 11 and multiple bypass diodes 16 connected in parallel with each cluster 11. Each cluster 11 is composed of multiple solar cells 12 connected in series. All the solar cells 12 constituting the solar panel 10 are connected in series. In this embodiment, the solar panel 10 has 3 clusters 11 and 3 bypass diodes 16. One cluster 11 is composed of 10 solar cells 12 connected in series. In addition, the number of clusters 11 and bypass diodes 16 in the solar panel 10 is not limited to 3. Furthermore, the number of solar cells 12 constituting one cluster 11 is not limited to 10.
[0026] When dirt adheres to the solar cell 12, the power generation of the corresponding solar cell 12 decreases because it is shaded. Since all solar cells 12 are connected in series, if the power generation of a portion of the solar cells 12 decreases, the overall power generation of the solar panel 10 decreases. Because the solar cell 12 with reduced power generation becomes a resistor, the current does not flow through the cluster 11 including the solar cell 12 with reduced power generation, but instead flows through the bypass diode 16 connected in parallel with the corresponding cluster 11. Thus, by providing the bypass diode 16, the cluster 11 including the solar cell 12 with reduced power generation can be electrically isolated. This suppresses the overall decrease in power generation of the solar panel 10, and also prevents the solar cell 12 with dirt from becoming a hot spot due to heat.
[0027] Current sensor 20 measures the current output from solar panel 10. Voltage sensor 30 measures the voltage output from solar panel 10.
[0028] The DC-DC converter 40 converts the voltage supplied from the solar panel 10 into the desired voltage and supplies it to the power receiving terminal 200. The power receiving terminal 200 is, for example, a battery installed in the vehicle 500 for storing the electricity generated by the solar panel 10. The DC-DC converter 40 controls the output voltage of the solar panel 10 according to the signal sent from the control unit 50.
[0029] The control unit 50 is a computer equipped with a processor and memory. The control unit 50 controls the operation of the solar system 100 by executing a program pre-stored in the memory via the processor. Alternatively, some or all of the functions of the control unit 50 can be implemented by hardware circuitry. The control unit 50 acquires the current value measured by the current sensor 20 and the voltage value measured by the voltage sensor 30, and sends drive commands to the DC-DC converter 40. The control unit 50 controls the power output from the solar panel 10 through Maximum Power Point Tracking (MPPT) control. This maximizes the power output from the solar panel 10.
[0030] Figure 2 This is an example of an IV curve showing the correlation between current and voltage values when the solar panel 10 is generating electricity normally. Figure 3 This is a graph illustrating an example of the IV curve when the power generation of a portion of solar cell 12 decreases. Figure 2 and Figure 3 In the diagram, the horizontal axis represents the voltage value measured by voltage sensor 30, and the vertical axis represents the current value measured by current sensor 20. For example... Figure 2 and Figure 3 As shown, if the power generation of a portion of the solar cells 12 decreases, the current value decreases, resulting in a step on the IV curve. The solar system 100 in this embodiment uses the step generated on the IV curve to estimate the area of dirt adhering to the solar panel 10.
[0031] Figure 4 This is a flowchart of the estimation process performed by the control unit 50. The control unit 50 estimates the area of dirt adhering to the solar panel 10 by performing the estimation process. In this embodiment, the estimation process includes MPPT control. That is, in this embodiment, the control unit 50 performs MPPT control by performing the estimation process. The time taken from the execution of the estimation process to its completion is preferably less than 1 second. Furthermore, the time taken from the execution of the estimation process to its completion is more preferably less than 0.3 seconds. The estimation process is repeatedly executed at a predetermined cycle. The estimation process is preferably repeatedly executed at a cycle of once per minute. In the estimation process, the control unit 50 changes the voltage output from the solar panel 10 at predetermined steps and obtains the current value corresponding to each voltage value from the current sensor 20. Figure 5Examples are shown in the diagram, including an IV curve representing the correlation between voltage and current values over a predetermined period, and a di / dv-V curve representing the correlation between differential conductance and voltage values (described later). Here, the predetermined period refers to the period during which one estimation process is performed. That is, the predetermined period is preferably less than 1 second, and more preferably less than 0.3 seconds.
[0032] In step S10, the control unit 50 acquires the voltage and current values output from the solar panel 10. The voltage value acquired in step S10 is a set value set by the control unit 50. The current value acquired in step S10 is the value measured by the current sensor 20 when the output voltage of the solar panel 10 is the aforementioned set value. The control unit 50 controls the output voltage from the solar panel 10 to become the aforementioned set value by sending a drive command to the DC-DC converter 40. The acquired voltage and current values are stored in a memory.
[0033] In step S20, the control unit 50 calculates the differential conductance di / dv. The differential conductance is the value obtained by differentiating the voltage value obtained in step S10 from the current value obtained in step S10. The value of the differential conductance is stored in the memory.
[0034] In step S30, the control unit 50 determines whether the differential conductance has changed from a value above a predetermined first threshold Th1 to a value below the first threshold Th1. Specifically, the control unit 50 determines whether the differential conductance calculated in step S20 one cycle ago was a value above the first threshold Th1 and whether the differential conductance calculated in step S20 of the current cycle is a value below the first threshold Th1. The first threshold Th1 is pre-stored in memory. If the differential conductance changes from a value above the first threshold to a value below the first threshold Th1, step S40 is executed. If the differential conductance does not change from a value above the predetermined first threshold to a value below the first threshold Th1, step S50 is executed.
[0035] In step S40, the control unit 50 stores the current value obtained in step S10 as a first current value I1 in its memory. Hereinafter, the voltage value at which the differential conductance changes from a value above a first threshold to a value smaller than the first threshold Th1 is referred to as the first voltage value V1. That is, the first current value I1 is the current value corresponding to the first voltage value V1 on the IV curve, which represents the correlation between current and voltage values over a predetermined period.
[0036] In step S50, the control unit 50 determines whether the differential conductance has changed from a value smaller than the first threshold Th1 to a value greater than or equal to the first threshold. Specifically, the control unit 50 determines whether the differential conductance calculated in step S20 one cycle ago was a value smaller than the first threshold Th1 and whether the differential conductance calculated in step S20 of the current cycle is a value greater than or equal to the first threshold. If the differential conductance has changed from a value smaller than the first threshold Th1 to a value greater than or equal to the first threshold, step S60 is executed. If the differential conductance has not changed from a predetermined value smaller than the first threshold Th1 to a value greater than or equal to the first threshold, step S100 is executed.
[0037] In step S60, the control unit 50 stores the current value obtained in step S10 as a second current value I2 in its memory. Hereinafter, the voltage value at which the differential conductance changes from a value smaller than the first threshold Th1 to a value greater than or equal to the first threshold is referred to as the second voltage value V2. That is, the second current value I2 is the current value corresponding to the second voltage value V2 on the IV curve, which represents the correlation between the current value and the voltage value over a predetermined period.
[0038] In step S70, the control unit 50 determines the state of the solar panel 10 based on the difference between the first current value I1 and the second current value I2. In this embodiment, the control unit 50 determines whether dirt adheres to the solar panel 10 based on the difference between the first current value I1 and the second current value I2. Specifically, the control unit 50 determines whether the value obtained by dividing the difference between the first current value I1 and the second current value I2 by the first current value I1 is greater than a predetermined step reference value. The step reference value is, for example, 0.5. Hereinafter, the value obtained by dividing the difference between the first current value I1 and the second current value I2 by the first current value I1 is also called the current difference ratio. If the current difference ratio is greater than or equal to the step reference value, the control unit 50 determines that dirt adheres to the solar panel 10. If the current difference ratio is less than the step reference value, the control unit 50 determines that no dirt adheres to the solar panel 10. If it is determined that dirt adheres to the solar panel 10, step S80 is executed. If it is determined that there is no dirt attached to the solar panel 10, step S100 is executed. Furthermore, if multiple first current values I1 are stored in the memory, the first current value I1 stored in the memory in the cycle closest to the current cycle is used to calculate the current difference ratio. And the second current value I2 used for calculating the current difference ratio is the second current value I2 stored in the memory in step S60 of the current cycle.
[0039] Figure 6 This is a graph illustrating the relationship between the difference between the first current value I1 and the second current value I2 and the area of dirt adhering to the solar panel 10. Figure 6In the diagram, the horizontal axis represents the current difference ratio, and the vertical axis represents the percentage of the total area of the solar panel 10 that is covered with dirt. For example... Figure 6 As shown, the percentage of the area with attached dirt is directly proportional to the current difference ratio. Figure 6 The relationship between the current difference ratio and the percentage of the area with dirt attached is pre-stored in the memory.
[0040] In step S80, the control unit 50 estimates the area of dirt adhering to the solar panel 10 based on the difference between the first current value I1 and the second current value I2. Specifically, the control unit 50 uses the current difference ratio calculated in step S70 and Figure 6 The corresponding relationship shown is used to calculate the percentage of the total area of the solar panel 10 that is covered with dirt.
[0041] In step S90, the control unit 50 controls a notification unit mounted on the vehicle 500 to notify the occupants of the vehicle 500 of the area of dirt adhering to the solar panel 10. The notification unit may be, for example, the dashboard of the vehicle 500. The control unit 50 displays the percentage of the total area of the solar panel 10 covered by dirt on the dashboard. Alternatively, the notification unit may be a speaker mounted on the vehicle 500. The control unit 50 can control the speaker to output the percentage of the total area of the solar panel 10 covered by dirt through sound.
[0042] In step S100, the control unit 50 determines whether to scan the voltage output from the solar panel 10 from the lower limit to the upper limit in a predetermined step, and obtains the current value corresponding to each voltage value from the current sensor 20. If the voltage has not been scanned from the lower limit to the upper limit, step S110 is executed. If the voltage has been scanned from the lower limit to the upper limit, step S120 is executed.
[0043] In step S110, the control unit 50 changes the voltage output from the solar panel 10. Specifically, the control unit 50 increases the set value of the voltage output from the solar panel 10 by a predetermined increment. After executing step S110, step S10 is executed again.
[0044] In step S120, the control unit 50 sets the voltage value output from the solar panel 10 to maximize the power output from the solar panel 10. The control unit 50 uses the voltage and current values obtained in the repeatedly executed step S10 to search for the voltage value that maximizes the power output from the solar panel 10. The control unit 50 sends a drive command to the DC-DC converter 40 to control the output voltage of the solar panel 10 so that the voltage value output from the solar panel 10 reaches the voltage value that maximizes the power output from the solar panel 10. The estimation process is performed in the manner described above.
[0045] As described above, the control unit 50 performs MPPT control by executing an estimation process. In this embodiment, during MPPT control, the control unit 50 searches for the voltage value at which the power output from the solar panel 10 is maximized by scanning the voltage output from the solar panel 10 from a lower limit to an upper limit. The estimation process includes steps S10, S100, S110, and S120, which are processes included in the MPPT control. Figure 5 The IV curve shown represents the correlation between the voltage and current values obtained by repeatedly executing step S10. That is, Figure 5 The IV curve shown was obtained during the execution of MPPT control.
[0046] According to the solar energy system 100 in the first embodiment described above, the control unit 50 determines the state of the solar panel 10 based on the difference between a first current value I1 and a second current value I2. The first current value I1 is the current value corresponding to the first voltage value V1 when the differential conductance changes from a value above a first threshold to a value smaller than the first threshold Th1 on the IV curve, which represents the correlation between current and voltage values over a predetermined period. The second current value I2 is the current value corresponding to the second voltage value V2 when the differential conductance changes from a value smaller than the first threshold Th1 to a value above the first threshold on the IV curve. As described above, the predetermined period is the period for performing the estimation process, preferably within 1 second, more preferably within 0.3 seconds. Therefore, by determining the state of the solar panel 10 within a short period, it is less susceptible to changes in external factors such as solar radiation intensity and the temperature of the solar panel 10. Therefore, the state of the solar panel 10 can be determined more accurately.
[0047] Furthermore, in this embodiment, the control unit 50 determines whether dirt adheres to the solar panel 10 based on the difference between the first current value I1 and the second current value I2. Therefore, it is possible to determine more accurately whether dirt adheres to the solar panel 10.
[0048] Furthermore, in this embodiment, the control unit 50 estimates the area of dirt adhering to the solar panel 10 based on the difference between the first current value I1 and the second current value I2. Therefore, the state of the solar panel 10 can be accurately estimated.
[0049] Furthermore, in this embodiment, the control unit 50 controls the notification unit mounted on the vehicle 500 to notify the occupants of the vehicle 500 of the area of dirt adhering to the solar panel 10. Therefore, the occupants of the vehicle 500 can confirm the area of dirt adhering to the solar panel 10.
[0050] Furthermore, in this embodiment, the control unit 50 controls the power output from the solar panel 10 through MPPT control. Figure 5 The IV curve shown is obtained during the execution of MPPT control. Therefore, compared with the cases where the state determination of solar panel 10 and MPPT control are performed separately, the state of solar panel 10 can be determined more efficiently.
[0051] B. Other implementation methods:
[0052] (B-1) In the above embodiment, the control unit 50 controls the notification unit mounted on the vehicle 500 to notify the occupants of the vehicle 500 of the area of dirt adhering to the solar panel 10. In contrast, the control unit 50 can control the notification unit mounted on the vehicle 500 not to notify the occupants of the vehicle 500 of the area of dirt adhering to the solar panel 10. That is, the estimation processing step S90 may not be performed.
[0053] (B-2) In the above embodiment, the control unit 50 estimates the area of dirt adhering to the solar panel 10 based on the difference between the first current value I1 and the second current value I2. In contrast, the control unit 50 may not estimate the area of dirt adhering to the solar panel 10. That is, the estimation process step S80 may not be performed. In this approach, if the control unit 50 determines during the estimation process that dirt is adhering to the solar panel 10, the control unit 50 may control the notification unit mounted on the vehicle 500 to notify the occupants of the vehicle 500 that dirt is adhering to the solar panel 10. Furthermore, if the control unit 50 determines during the estimation process that dirt is adhering to the solar panel 10, the control unit 50 may control the notification unit mounted on the vehicle 500 not to notify the occupants of the vehicle 500 of the area of dirt adhering to the solar panel 10.
[0054] (B-3) In the above embodiment, the control unit 50 determines whether dirt is attached to the solar panel 10 based on the difference between the first current value I1 and the second current value I2. In contrast, the control unit 50 can determine whether the solar panel 10 has malfunctioned based on the difference between the first current value I1 and the second current value I2.
[0055] (B-4) In the above embodiment, the control unit 50 performs MPPT control by performing estimation processing. In contrast, the control unit 50 can perform estimation processing and MPPT control independently. In this case, step S120 of estimation processing is not performed. Furthermore, in MPPT control, the control unit 50 can use a hill-climbing method to search for the voltage value where the power output from the solar panel 10 is the maximum.
[0056] (B-5) In the above embodiment, the solar energy system 100 can be mounted on a movable vehicle 500. Alternatively, the solar energy system 100 may not be mounted on the vehicle 500.
[0057] This invention is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects, the technical features in the embodiments corresponding to the technical features in the various forms described in the summary section of the invention can be appropriately replaced or combined. Furthermore, if a technical feature is not required to be described in this specification, it can be appropriately deleted.
[0058] Symbol Explanation
[0059] 10-Solar panel, 11-Cluster, 12-Solar cell, 16-Bypass diode, 20-Current sensor, 30-Voltage sensor, 40-DC-DC converter, 50-Control unit, 100-Solar system, 200-Power receiving end, 500-Vehicle, I1-First current value, I2-Second current value, Th1-First threshold, V1-First voltage value, V2-Second voltage value.
Claims
1. A solar energy system capable of being mounted on a vehicle, said solar energy system being characterized by comprising: Solar panels; A current sensor that measures the current value output from the solar panel; A voltage sensor that measures the voltage value output from the solar panel; and The control unit determines the state of the solar panel based on the difference between the first current value and the second current value. The first current value is the current value corresponding to the voltage value (i.e., the first voltage value) at the time the differential conductance changes from a value above a predetermined first threshold to a value below the first threshold on the IV curve representing the correlation between the current value and the voltage value over a predetermined period. The second current value is the current value corresponding to the voltage value at this time, i.e., the second voltage value, when the differential conductance changes from a value smaller than the first threshold to a value greater than the first threshold on the IV curve.
2. The solar energy system according to claim 1, characterized in that, The control unit determines whether there is dirt on the solar panel based on the difference between the first current value and the second current value.
3. The solar energy system according to claim 2, characterized in that, The control unit estimates the area of dirt adhering to the solar panel based on the difference between the first current value and the second current value.
4. The solar energy system according to claim 3, characterized in that, The control unit controls the notification unit mounted on the vehicle to notify the occupants of the area of dirt attached to the solar panel.
5. The solar energy system according to claim 1, characterized in that, The control unit controls the power output from the solar panel via MPPT (Maximum Power Point Tracking). The IV curve is obtained during the execution of the MPPT control.