Photovoltaic system, related method and storage medium
By dynamically adjusting the angle of the multi-junction bifacial solar cell through a tracking system and control unit, the current mismatch problem caused by changes in temperature, spectrum, and ground reflection is solved, thereby maximizing the total current and total efficiency of the multi-junction bifacial solar cell.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-04-14
AI Technical Summary
Multijunction bifacial solar cells suffer from reduced efficiency in outdoor environments due to variations in temperature, spectrum, and ground reflection, leading to current mismatch between individual cells.
A tracking system and control unit are used to dynamically adjust the angle between the multi-junction bifacial solar cell and the ground, and adjust the irradiance of the front and back sides to match the current of each sub-cell.
It effectively solves the current mismatch problem caused by changes in temperature, spectrum and ground reflection, and maximizes the total current and total efficiency of multi-junction bifacial solar cells.
Smart Images
Figure CN121863989A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of photovoltaic technology, and more specifically, to photovoltaic systems, related methods, and storage media. Background Technology
[0002] Compared to single-junction solar cells, multi-junction bifacial solar cells can utilize the full spectrum more effectively, resulting in higher cell efficiency. Currently, in outdoor environments, temperature, spectrum, and ground reflection vary with location, season, and time of day. These variations affect the top and bottom cells of a multi-junction bifacial solar cell differently, leading to current mismatch between the sub-cells and reduced cell efficiency. Summary of the Invention
[0003] This application provides a photovoltaic system. The photovoltaic system includes a multi-junction bifacial solar cell with contacts at both ends, a tracking system, and a control unit. The multi-junction bifacial solar cell includes multiple sub-cells with different band gaps, which are connected in series. The tracking system is used to adjust the angle of the multi-junction bifacial solar cell relative to the ground. The control unit is configured to control the tracking system to adjust the angle of the multi-junction bifacial solar cell relative to the ground based on the real-time current state of the multiple sub-cells, thereby adjusting the irradiance received by the front and / or back of the multi-junction bifacial solar cell to match the current of the multiple sub-cells.
[0004] The photovoltaic system of the first aspect of this application dynamically adjusts the angle between the multi-junction bifacial solar cell and the sun and the ground based on the current state of each sub-cell through the tracking system and the algorithm control of the control unit. This controls the irradiance on the front and back of the multi-junction bifacial solar cell, enabling current matching between the sub-cells. This helps to solve the problem of current mismatch loss caused by changes in temperature, spectrum and ground reflection under outdoor conditions, thereby maximizing the total current and total efficiency of the multi-junction bifacial solar cell.
[0005] In some embodiments, the tracking system is configured to rotate the multi-junction bifacial solar cell along the east-west and / or north-south directions.
[0006] In some embodiments, the angle between the multi-junction bifacial solar cell and the ground is adjustable from -90° to 90°.
[0007] In some embodiments, the multi-junction bifacial solar cell includes a top cell and a bottom cell. The control unit is configured to: when the photocurrent of the top cell is higher than that of the bottom cell, control the tracking system to increase the angle between the multi-junction bifacial solar cell and the ground to increase the photocurrent of the bottom cell and decrease the photocurrent of the top cell; and when the photocurrent of the top cell is lower than that of the bottom cell, control the tracking system to decrease the angle between the multi-junction bifacial solar cell and the ground to increase the photocurrent of the top cell and decrease the photocurrent of the bottom cell.
[0008] In some embodiments, the multi-junction bifacial solar cell is a double-junction tandem bifacial solar cell, comprising a top cell and a bottom cell; the top cell is a perovskite solar cell with a bandgap ranging from 1.0 eV to 2.1 eV; and the bottom cell is a crystalline silicon solar cell with a bandgap ranging from 0.7 eV to 1.6 eV.
[0009] In some embodiments, the multi-junction bifacial solar cell includes a top cell, at least one intermediate cell, and a bottom cell; the top cell and the intermediate cell are perovskite solar cells with different band gaps, and the bottom cell is a crystalline silicon solar cell.
[0010] In some embodiments, the bandgap of the top cell ranges from 1.2 eV to 2.2 eV; the bandgap of the middle cell ranges from 1.0 eV to 1.8 eV; and the bandgap of the bottom cell ranges from 0.7 eV to 1.4 eV.
[0011] In some embodiments, the multi-junction bifacial solar cell further includes a down-conversion material layer; the down-conversion material layer is disposed above the top cell and / or below the bottom cell.
[0012] A second aspect of this application provides a control method for a multi-junction bifacial solar cell, applied to the photovoltaic system of the first aspect of this application. The control method includes: in response to current mismatch among multiple sub-cells, controlling a tracking system to adjust the angle between the multi-junction bifacial solar cell and the ground, thereby adjusting the irradiance received on the front side and / or the irradiance received on the back side of the multi-junction bifacial solar cell to achieve current matching among the multiple sub-cells.
[0013] The control method for multi-junction bifacial solar cells of the second aspect of this application has at least the same advantages as the photovoltaic system of the first aspect of this application, and will not be described in detail here.
[0014] In some embodiments, adjusting the angle between the multi-junction bifacial solar cell and the ground specifically includes: increasing the angle between the multi-junction bifacial solar cell and the ground when the photocurrent of the top cell is higher than that of the bottom cell; and decreasing the angle between the multi-junction bifacial solar cell and the ground when the photocurrent of the top cell is lower than that of the bottom cell.
[0015] In some embodiments, adjusting the angle between the multi-junction bifacial solar cell and the ground includes: predicting the irradiance received by the front and back sides of the multi-junction bifacial solar cell based on the latitude and longitude of the application location of the multi-junction bifacial solar cell, outdoor irradiance data, solar angle, and the current orientation and tilt angle of the multi-junction bifacial solar cell; actually measuring the irradiance received by the front and back sides of the multi-junction bifacial solar cell using a spectrometer or spectroradiometer and correcting the predicted values; and adjusting the angle between the multi-junction bifacial solar cell and the ground based on the corrected irradiance received by the front and back sides.
[0016] A third aspect of this application provides a design method for a multi-junction bifacial solar cell with contacts at both ends. The multi-junction bifacial solar cell module includes a top cell and a bottom cell, wherein the top cell is a perovskite solar cell and the bottom cell is a crystalline silicon solar cell. The design method includes: Compare the spectrum of the multi-junction bifacial solar cell at the application site with the standard test spectrum; if the spectrum at the application site has higher intensity in the short wavelength range and lower intensity in the long wavelength range, then the band gap of the perovskite solar cell is set as the first band gap; if the spectrum at the application site has lower intensity in the short wavelength range and higher intensity in the long wavelength range, then the band gap of the top cell is set as the second band gap, the second band gap being larger than the first band gap, with 700 nm as the boundary between the long and short wavelength ranges; and / or If the average temperature at the application location is higher than 25°C, the band gap of the top battery is set to the third band gap. If the average temperature at the application location is lower than 25°C, the band gap of the top battery is set to the fourth band gap, which is smaller than the third band gap.
[0017] The design method for multi-junction bifacial solar cells in the third aspect of this application addresses the issue that in multi-junction bifacial solar cells, the perovskite top cell primarily absorbs short-wavelength light, while the crystalline silicon bottom cell primarily absorbs long-wavelength light. By comparing the spectrum of the application location with the standard test spectrum, if the spectrum at the application location has a higher short-wavelength range and a lower long-wavelength range compared to the standard test spectrum, the top cell absorbs more light. Therefore, a wide bandgap perovskite cell is required to allow more light to be absorbed by the bottom cell, and vice versa. Furthermore, at locations with an average temperature above 25°C, a lower bandgap perovskite top cell is used, while at locations with an average temperature below 25°C, a higher bandgap perovskite top cell is used. This is because as temperature increases, the bandgap of the perovskite cell increases, resulting in a decrease in current, while the bandgap of the crystalline silicon cell decreases, resulting in an increase in current, leading to current mismatch. Therefore, in product design, a narrower bandgap top cell is needed at high-temperature locations, while a wider bandgap top cell is needed at low-temperature locations to achieve current matching.
[0018] The fourth aspect of this application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the control method for a multi-junction bifacial solar cell according to the second aspect of this application or the design method for a multi-junction bifacial solar cell according to the third aspect of this application. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the structure of a photovoltaic system according to an embodiment of this application.
[0020] Figure 2 for Figure 1 A schematic diagram of a multi-junction bifacial solar cell.
[0021] Figure 3 is Figure 1 Another structural schematic diagram of the multi-junction double-sided solar cell in
[0022] Figure 4 In the photovoltaic system according to an embodiment of the present application, it is a schematic diagram of the rotation direction of the multi-junction double-sided solar cell.
[0023] Figure 5 In the photovoltaic system according to another embodiment of the present application, it is a schematic diagram of the rotation direction of the multi-junction double-sided solar cell.
[0024] Figure 6 In the photovoltaic system according to still another embodiment of the present application, it is a schematic diagram of the rotation direction of the multi-junction double-sided solar cell.
[0025] Main element symbol description: Photovoltaic system - 100; Multi-junction double-sided solar cell - 10; Top cell - 11; Bottom cell - 12; Intermediate cell - 13; Tracking system - 20; Control unit - 30.
[0026] The following specific embodiments will further illustrate the present application in conjunction with the above-mentioned drawings. Specific embodiments
[0027] The following details the embodiments of the present application. The examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.
[0028] It should be noted that terms such as "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Terms such as "exemplarily" or "for example" are used to represent examples, illustrations or explanations and should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Specifically, using words such as "exemplarily" or "for example" aims to present relevant concepts in a specific manner.
[0029] The data range values recorded in the embodiments of the present application should include the end values unless otherwise specified.
[0030] Unless otherwise defined, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or integrated; it can be directly connected or indirectly connected through an intermediate medium.
[0031] Refer Figure 1 , the photovoltaic system 100 of the embodiment of the present application includes a multi-junction double-sided solar cell 10 with two ends in contact, a tracking system 20, and a control unit 30.
[0032] The multi-junction bifacial solar cell 10 includes multiple sub-cells with different band gaps. These sub-cells are connected in series. A tracking system 20 is used to adjust the angle of the multi-junction bifacial solar cell 10 relative to the ground. A control unit 30 is configured to control the tracking system 20 to adjust the angle of the multi-junction bifacial solar cell 10 relative to the ground based on the real-time current state of the multiple sub-cells, thereby adjusting the irradiance received by the front and / or back of the multi-junction bifacial solar cell 10 to match the currents of the multiple sub-cells.
[0033] It should be noted that in multi-junction bifacial solar cells with contacts at both ends, since multiple sub-cells are connected in series, the minimum current rule of series circuits must be met. Only when the current of the two sub-cells is maximized and equal can the total current and total efficiency of the multi-junction bifacial solar cell at both ends be maximized. In outdoor photovoltaic system applications, temperature, spectrum, and ground reflection vary with location, season, and different times of day. In multi-junction bifacial solar cells with contacts at both ends, the effects on the top and bottom cells are different, leading to current mismatch between the top and bottom cells and resulting in lower efficiency of the tandem solar cells in practical applications.
[0034] In the photovoltaic system 100 of this application embodiment, the multi-junction bifacial solar cell 10, which is contacted at both ends, is composed of two or more sub-cells with different band gaps. Through algorithmic control by the tracking system 20 and the control unit 30, the angle between the multi-junction bifacial solar cell 10 and the sun and the ground is dynamically adjusted according to the current state of each sub-cell. This controls the irradiance on the front and back of the multi-junction bifacial solar cell 10, ensuring current matching between the sub-cells. This helps to solve the current mismatch loss problem caused by changes in temperature, spectrum, and ground reflection under outdoor conditions, thereby maximizing the total current and overall efficiency of the multi-junction bifacial solar cell 10. Algorithmic control can be achieved using algorithms such as particle swarm optimization. Current matching refers to the current of the top cell being equal to or close to the current of the bottom cell.
[0035] In some embodiments, the multi-junction bifacial solar cell 10 is a double-junction tandem bifacial solar cell. (See reference...) Figure 2 The multi-junction bifacial solar cell 10 includes a top cell 11 and a bottom cell 12. The top cell 11 is a perovskite solar cell with a bandgap ranging from 1.0 eV to 2.1 eV (e.g., 1.0 eV to 1.5 eV, 1.5 eV to 1.9 eV, 1.9 eV to 2.1 eV). The bottom cell 12 is a crystalline silicon solar cell with a bandgap ranging from 0.7 eV to 1.6 eV (e.g., 0.7 eV to 1.1 eV, 1.1 eV to 1.12 eV, 1.12 eV to 1.5 eV, 1.5 eV to 1.6 eV).
[0036] In the above embodiments, by combining wide-bandgap perovskite solar cells with narrow-bandgap crystalline silicon solar cells, compared with single-junction solar cells, the full spectrum can be utilized more effectively, resulting in higher cell efficiency.
[0037] Furthermore, because temperature, spectrum, and ground reflection vary with location, season, and time, they have different effects on the perovskite top cell and crystalline silicon bottom cell of the perovskite / crystalline silicon solar cells at both ends, leading to current mismatch between the perovskite top cell and the crystalline silicon bottom cell, resulting in lower efficiency of the tandem cells in practical applications. In the embodiments of this application, the setting of the tracking system 20 and the control unit 30 helps to solve the problem of current mismatch between the perovskite top cell 11 and the crystalline silicon bottom cell 12 in practical applications.
[0038] In some embodiments, the multi-junction bifacial solar cell 10 is a bifacial solar cell with two ends of a double-junction tandem structure, and perovskite solar cells are directly fabricated on crystalline silicon solar cells to reduce fabrication costs and system costs.
[0039] In some embodiments, the multi-junction bifacial solar cell 10 includes a top cell 11, a bottom cell 12, and at least one intermediate cell 13. The top cell 11 and the intermediate cell 13 are perovskite solar cells with different band gaps, and the bottom cell 12 is a crystalline silicon solar cell.
[0040] In the above embodiments, the multi-junction bifacial solar cell 10 is a triple-junction or more junction stacked cell, which is beneficial to further broaden the spectral utilization range.
[0041] In some embodiments, the multi-junction bifacial solar cell 10 is a triple-junction tandem bifacial solar cell. (See reference...) Figure 3 The multi-junction bifacial solar cell 10 includes three sub-cells: a top cell 11, a middle cell 13, and a bottom cell 12. The top cell 11 and the middle cell 13 are perovskite solar cells with different band gaps, while the bottom cell 12 is a crystalline silicon solar cell.
[0042] In some embodiments, the multi-junction bifacial solar cell 10 employs a triple-junction bifacial solar cell composed of three sub-cells with different bandgap values. The bandgap range of the top cell 11 is 1.2 eV to 2.2 eV (e.g., 1.2 eV to 1.5 eV, 1.5 eV to 1.7 eV, 1.7 eV to 2.0 eV, 2.0 eV to 2.1 eV, 2.1 eV to 2.2 eV), and the bandgap range of the middle cell 13 is... The band gap of the bottom cell 12 is 0.7eV to 1.4eV (e.g., 0.7eV to 1.1eV, 1.1eV to 1.12eV, 1.12eV to 1.3eV, 1.3eV to 1.4eV).
[0043] In the above embodiments, the gradient distribution of the triple-junction bandgap facilitates better current matching.
[0044] In some embodiments, the multi-junction bifacial solar cell 10 further includes a down-conversion material layer (not shown). The down-conversion material layer is disposed above the top cell 11.
[0045] In the above embodiments, by providing a downconversion material layer above the top cell 11, a portion of the high-energy sunlight incident on the multi-junction bifacial solar cell 10 can be converted into a spectrum more favorable to the top cell 11 and the sub-cells below the top cell 11, thereby improving the spectral utilization rate.
[0046] In some embodiments, the multi-junction bifacial solar cell 10 further includes a downconversion material layer (not shown) disposed below the bottom cell 12.
[0047] In the above embodiments, by providing a downconversion material layer below the bottom cell 12, high-energy photons incident from the back can be converted into wavelengths that the bottom cell 12 can effectively utilize, thereby improving spectral utilization.
[0048] In some embodiments, downconversion material layers are provided above the top cell 11 and below the bottom cell 12. This avoids wasting light from the front and back sides and improves spectral utilization.
[0049] For example, the material of the downconversion material layer above the top cell 11 and / or below the bottom cell 12 can be, but is not limited to, quantum dot materials (such as CdS quantum dots, ZnS quantum dots, CsPbBr3 quantum dots, etc.) or rare earth ion doped materials (such as Eu). 3+ Doped materials, Tb 3+ Doped materials, organic fluorescent dyes, and nanophosphors (such as CeO2:Eu) 3+ Sr2F:Eu 3+ (e.g., nanoparticles).
[0050] In some embodiments, the tracking system 20 is configured to rotate the multi-junction bifacial solar cell 10 about a single axis. For example, see... Figure 4 The tracking system 20 is configured to cause the multi-junction bifacial solar cell 10 to rotate about a single axis, specifically in an east-west direction. For example, see... Figure 5 The tracking system 20 is configured to cause the multi-junction bifacial solar cell 10 to rotate about a single axis and in the north-south direction.
[0051] In some embodiments, the tracking system 20 is configured to rotate the multi-junction bifacial solar cell 10 about two axes. For example, see... Figure 6The multi-junction bifacial solar cell 10 can rotate both east-west and north-south.
[0052] In the above embodiments, the tracking system 20 provides the multi-junction bifacial solar cell 10 with a single-axis or dual-axis rotational degree of freedom, making the angle adjustment of the multi-junction bifacial solar cell 10 more flexible and advantageous for adapting to different installation conditions and lighting conditions.
[0053] In some embodiments, the angle between the multi-junction bifacial solar cell 10 and the ground is adjustable from -90° to 90°. The 0° angle reference is defined as the multi-junction bifacial solar cell 10 being parallel to the ground. When the multi-junction bifacial solar cell 10 rotates upward counterclockwise, the angle increases from 0° to 90° (perpendicular to the ground); when the multi-junction bifacial solar cell 10 rotates downward clockwise, the angle decreases from 0° to -90° (perpendicular to the ground, in the opposite direction to the 90° angle).
[0054] In the above embodiments, the angle adjustment range between the multi-junction bifacial solar cell 10 and the ground is wide, which is beneficial to enhance the adaptability of the photovoltaic system 100 to different light conditions. It allows the multi-junction bifacial solar cell 10 to significantly adjust the back irradiance under extreme conditions, such as morning or evening, or different ground reflectivities, thereby more effectively balancing the photocurrent of the top cell 11 and the bottom cell 12.
[0055] In some embodiments, the tracking system 20 includes a bracket (not shown), a drive motor (not shown), and an angle sensor (not shown). The bracket is used to fix the multi-junction bifacial solar cell 10. The drive motor may be, but is not limited to, a stepper motor or a linear actuator. There may be one or more drive motors connected to the bracket to drive the bracket to rotate the multi-junction bifacial solar cell 10 in a single-axis or dual-axis manner, thereby changing the angle between the multi-junction bifacial solar cell 10 and the ground. The angle sensor is used to monitor the tilt angle of the multi-junction bifacial solar cell 10 in real time.
[0056] In some embodiments, the control unit 30 is configured to: when the photocurrent of the top cell 11 is higher than the photocurrent of the bottom cell 12, control the tracking system 20 to increase the angle between the multi-junction bifacial solar cell 10 and the ground, thereby increasing the photocurrent of the bottom cell 12 and decreasing the photocurrent of the top cell 11; when the photocurrent of the top cell 11 is lower than the photocurrent of the bottom cell 12, control the tracking system 20 to decrease the angle between the multi-junction bifacial solar cell 10 and the ground, thereby increasing the photocurrent of the top cell 11 and decreasing the photocurrent of the bottom cell 12. This achieves current matching and ensures the maximization of the overall current of the multi-junction bifacial solar cell.
[0057] In the above embodiments, by increasing or decreasing the angle between the multi-junction bifacial solar cell 10 and the ground, the back irradiance can be adjusted, which is beneficial to achieving rapid current matching.
[0058] This application also provides a control method for a multi-junction bifacial solar cell, applied to the photovoltaic system 100 described above. Depending on different requirements, the order of certain steps or sub-steps in the control method for the multi-junction bifacial solar cell can be changed, and certain steps or sub-steps can be omitted or combined.
[0059] The control method for the multi-junction bifacial solar cell includes: in response to current mismatch between multiple sub-cells, controlling the tracking system to adjust the angle of the multi-junction bifacial solar cell with respect to the ground, thereby adjusting the irradiance received on the front side and / or the irradiance received on the back side of the multi-junction bifacial solar cell to match the current of the multiple sub-cells.
[0060] The control method for multi-junction bifacial solar cells described above, by dynamically responding to the current mismatch of sub-cells, facilitates real-time optimization, thereby maximizing the total current and total efficiency of multi-junction bifacial solar cells.
[0061] In some embodiments, adjusting the angle between the multi-junction bifacial solar cell and the ground specifically includes: increasing the angle between the multi-junction bifacial solar cell and the ground when the photocurrent of the top cell is higher than that of the bottom cell; and decreasing the angle between the multi-junction bifacial solar cell and the ground when the photocurrent of the top cell is lower than that of the bottom cell. The photocurrent can be calculated using a spectrometer or radiometer in conjunction with the quantum efficiency curves of each sub-cell.
[0062] In the above embodiments, by increasing or decreasing the angle between the multi-junction bifacial solar cell and the ground, the current of the top and bottom cells can be controlled, making it easy to quickly converge to the current matching state.
[0063] In some embodiments, adjusting the angle between the multi-junction bifacial solar cell and the ground includes the following steps S10 to S30.
[0064] S10: Based on the latitude and longitude of the application location of the multi-junction bifacial solar cell, outdoor irradiance data, solar angle, and the current orientation and tilt angle of the multi-junction bifacial solar cell, predict the irradiance received by the front and back sides of the multi-junction bifacial solar cell.
[0065] In some embodiments, outdoor irradiance data are obtained from weather stations or environmental monitoring stations, or from the National Aeronautics and Space Administration (NASA).
[0066] In some embodiments, in S10, based on the latitude and longitude of the application location of the multi-junction bifacial solar cell and combined with outdoor irradiance data, the multi-junction bifacial solar cell and the ground location are calculated using software (such as Excel, SAM, or PVsyst software) to preliminarily predict the irradiance for generating electricity by receiving sunlight on the front side and the irradiance for generating electricity by receiving reflected sunlight from the ground on the back side.
[0067] S20: Use a spectrometer or radiometer to actually test the irradiance received on the front and back sides of the multi-junction bifacial solar cell and correct the predicted value in S10.
[0068] S30: Adjust the angle of the multi-junction bifacial solar cell to the ground based on the corrected irradiance received on the front and back sides.
[0069] In some embodiments, in S30, the multi-junction bifacial solar cell can be rotated from south to north, or from east to west, or simultaneously from south to north and from east to west, by a tracking system, and the angle between the multi-junction bifacial solar cell and the ground can be from -90° to 90°.
[0070] It should be noted that the irradiance received by the front side of a multi-junction bifacial solar cell is related to the latitude and longitude of the power generation location, the solar angle at different times of day, and the orientation and angle of the multi-junction bifacial solar cell. Once the latitude and longitude of the power generation location are determined, the irradiance received by the front side of the multi-junction bifacial solar cell is mainly related to the solar angle and the orientation of the multi-junction bifacial solar cell. Therefore, in step S30, the amount of irradiance received by the front side can be adjusted according to the solar angle at different times and locations. The angle between the multi-junction bifacial solar cell and the ground also changes the solar angle.
[0071] Furthermore, the irradiance on the back side of a multi-junction bifacial solar cell is related to the latitude and longitude of the power generation location, as well as the orientation and angle of the multi-junction bifacial solar cell. Once the latitude and longitude of the power generation location are determined, it is mainly related to the angle between the multi-junction bifacial solar cell and the ground.
[0072] Therefore, the irradiance of the front and back sides of a multi-junction bifacial solar cell is mainly related to the angle between the multi-junction bifacial solar cell and the ground. When the top cell generates less power and the bottom cell generates more power, the angle between the multi-junction bifacial solar cell and the ground can be reduced to decrease the power generation of the bottom cell, thus achieving current matching. Conversely, when the top cell generates more power and the bottom cell generates less power, the angle between the multi-junction bifacial solar cell and the ground can be increased to increase the power generation of the bottom cell, thus achieving current matching.
[0073] In the above embodiments, combining prediction with real-time measurement improves adjustment accuracy and reliability, and adapts to complex outdoor environments. Understandably, the irradiance received by the front and back sides of the multi-junction bifacial solar cell is an intermediate parameter, ultimately aimed at maximizing power generation. The control unit can adjust one or more parameters of the multi-junction bifacial solar cell to adjust the irradiance received by the front and back sides of the cell.
[0074] This application also provides a design method for a multi-junction bifacial solar cell with contacts at both ends. The multi-junction bifacial solar cell module includes a top cell and a bottom cell, wherein the top cell is a perovskite solar cell and the bottom cell is a crystalline silicon solar cell. The design method for the multi-junction bifacial solar cell with contacts at both ends includes designing the bandgap of the top cell based on the climate and sunlight distribution of the application location.
[0075] In some embodiments, the spectrum of the multi-junction bifacial solar cell at the application site is compared with a standard test spectrum. If the spectrum at the application site has higher intensity in the short-wavelength band and lower intensity in the long-wavelength band, the band gap of the perovskite solar cell is set as the first band gap. If the spectrum at the application site has lower intensity in the short-wavelength band and higher intensity in the long-wavelength band, the band gap of the top cell is set as the second band gap, which is larger than the first band gap, with 700 nm as the boundary between the long-wavelength and short-wavelength bands.
[0076] It should be noted that the standard test spectrum is the standard test spectrum for AM1.5G solar cells. In multi-junction bifacial solar cells, the perovskite top cell mainly absorbs short-wavelength (≤700nm) light, while the crystalline silicon bottom cell mainly absorbs long-wavelength (>700nm) light. Comparing the local AM1.5G spectrum with the standard AM1.5G spectrum reveals that the local AM1.5G spectrum has a higher short-wavelength range and a lower long-wavelength range compared to the standard AM1.5G spectrum. This means the top cell absorbs more light, thus requiring a wide-bandgap perovskite cell to allow more light to be absorbed by the bottom cell, and vice versa.
[0077] In some embodiments, if the average temperature of the application location is higher than 25°C, the band gap of the top battery is set as the third band gap; if the average temperature of the application location is lower than 25°C, the band gap of the top battery is set as the fourth band gap, and the fourth band gap is smaller than the third band gap.
[0078] It should be noted that the standard test temperature for solar cells is 25°C. If the average temperature at the application site is higher than 25°C, it is defined as high temperature; if the average temperature at the application site is lower than 25°C, it is defined as low temperature.
[0079] In the above embodiments, perovskite top cells with a narrower bandgap are used at high-temperature locations, while perovskite top cells with a higher bandgap are used at low-temperature locations. This is because as temperature increases, the bandgap of perovskite cells increases, resulting in a decrease in current, while the bandgap of crystalline silicon cells decreases, resulting in an increase in current, leading to current mismatch. In product design, top cells with narrower bandgap are needed at high-temperature locations, while top cells with wider bandgap are needed at low-temperature locations to achieve current matching.
[0080] The specific range of the bandgap for the top cell is not limited, depending on the different application scenarios and standard testing conditions.
[0081] In some embodiments, the bandgap range of the top cell can be set independently for the spectrum and temperature of the application site, but it is not limited to this.
[0082] In some embodiments, the bandgap range of the top cell can be set by taking into account the combined effects of the spectrum and temperature at the application location.
[0083] This application also provides a computer-readable storage medium. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the control method or design method for the multi-junction bifacial solar cell described above.
[0084] Computer programs include computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. Computer-readable media can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), and random access memory (RAM).
[0085] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to the above preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of this application should not depart from the spirit and scope of the technical solutions of this application.
Claims
1. A photovoltaic system, characterized in that, include: A multi-junction bifacial solar cell with contacts at both ends includes multiple sub-cells with different band gaps, and each sub-cell is connected in series. A tracking system is used to adjust the angle of the multi-junction bifacial solar cell relative to the ground; as well as The control unit is configured to: control the tracking system to adjust the angle of the multi-junction bifacial solar cell with respect to the ground based on the real-time current state of the multiple sub-cells, thereby adjusting the irradiance received by the front and / or back of the multi-junction bifacial solar cell to match the current of the multiple sub-cells.
2. The photovoltaic system according to claim 1, characterized in that: The tracking system is configured to rotate the multi-junction bifacial solar cell along an east-west and / or north-south direction; and / or The angle between the multi-junction bifacial solar cell and the ground can be adjusted from -90° to 90°.
3. The photovoltaic system according to claim 1, characterized in that: The multi-junction bifacial solar cell includes a top cell and a bottom cell, and the control unit is configured to: When the photocurrent of the top cell is higher than that of the bottom cell, the tracking system is controlled to increase the angle between the multi-junction bifacial solar cell and the ground, so as to increase the photocurrent of the bottom cell and decrease the photocurrent of the top cell. as well as When the photocurrent of the top cell is lower than that of the bottom cell, the tracking system is controlled to reduce the angle between the multi-junction bifacial solar cell and the ground, so as to increase the photocurrent of the top cell and decrease the photocurrent of the bottom cell.
4. The photovoltaic system according to claim 1, characterized in that: The multi-junction bifacial solar cell is a double-junction tandem bifacial solar cell, and includes a top cell and a bottom cell; The top cell is a perovskite solar cell with a bandgap ranging from 1.0 eV to 2.1 eV; The bottom cell is a crystalline silicon solar cell with a bandgap ranging from 0.7 eV to 1.6 eV.
5. The photovoltaic system according to claim 1, characterized in that: The multi-junction bifacial solar cell includes a top cell, at least one intermediate cell, and a bottom cell; The top cell and the middle cell are perovskite solar cells with different band gaps, and the bottom cell is a crystalline silicon solar cell.
6. The photovoltaic system according to claim 5, characterized in that: The bandgap of the top cell ranges from 1.2 eV to 2.2 eV; The bandgap of the intermediate cell ranges from 1.0 eV to 1.8 eV; The band gap of the bottom cell ranges from 0.7 eV to 1.4 eV.
7. The photovoltaic system according to any one of claims 4 to 6, characterized in that: The multi-junction bifacial solar cell also includes a down-conversion material layer; The downconversion material layer is disposed above the top cell and / or below the bottom cell.
8. A method for controlling a multi-junction bifacial solar cell, applied to a photovoltaic system as described in any one of claims 1 to 7, characterized in that, include: In response to current mismatch among the multiple sub-cells, the tracking system is controlled to adjust the angle of the multi-junction bifacial solar cell with respect to the ground, thereby adjusting the irradiance received on the front and / or back of the multi-junction bifacial solar cell to match the current of the multiple sub-cells.
9. The control method for multi-junction bifacial solar cells according to claim 8, characterized in that, The multi-junction bifacial solar cell includes a top cell and a bottom cell, and adjusting the angle between the multi-junction bifacial solar cell and the ground specifically includes: When the photocurrent of the top cell is higher than that of the bottom cell, the angle between the multi-junction bifacial solar cell and the ground is increased; and When the photocurrent of the top cell is lower than that of the bottom cell, the angle between the multi-junction bifacial solar cell and the ground is reduced.
10. The control method for multi-junction bifacial solar cells according to claim 8, characterized in that, The adjustment of the angle between the multi-junction bifacial solar cell and the ground includes: Based on the latitude and longitude of the application location of the multi-junction bifacial solar cell, outdoor irradiance data, solar angle, and the current orientation and tilt angle of the multi-junction bifacial solar cell, the irradiance received by the front and back sides of the multi-junction bifacial solar cell is predicted. The irradiance received on the front and back sides of the multi-junction bifacial solar cell was actually measured using a spectrometer or radiometer, and the predicted values were corrected; and The angle between the multi-junction bifacial solar cell and the ground is adjusted based on the corrected irradiance received on the front and back sides.
11. A design method for a multi-junction bifacial solar cell with contacts at both ends, characterized in that, The multi-junction bifacial solar cell module includes a top cell and a bottom cell, wherein the top cell is a perovskite solar cell and the bottom cell is a crystalline silicon solar cell; the design method includes: The spectrum of the multi-junction bifacial solar cell at its application site is compared with the standard test spectrum. If the spectrum at the application site has higher intensity in the short-wavelength band and lower intensity in the long-wavelength band, then the band gap of the perovskite solar cell is set as the first band gap. If the spectrum at the application site has lower intensity in the short-wavelength band and higher intensity in the long-wavelength band, then the band gap of the top cell is set as the second band gap, where the second band gap is larger than the first band gap, and the long-wavelength band and the short-wavelength band are separated by 700 nm. And / or If the average temperature at the application location is higher than 25°C, the band gap of the top battery is set as the third band gap; if the average temperature at the application location is lower than 25°C, the band gap of the top battery is set as the fourth band gap, and the fourth band gap is smaller than the third band gap.
12. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the control method for a multi-junction bifacial solar cell as described in any one of claims 8 to 10 or the design method for a multi-junction bifacial solar cell as described in claim 11.