Method for determining the transparency of an insulating material and the bifaciality of a back contact assembly

Abstract

The application discloses a method for determining the transparency of insulating material and the bifaciality of a back contact component, relates to the technical field of photovoltaic cells, and aims to determine the transparency of insulating material, thereby improving the calculation accuracy of the bifaciality of a back contact cell or a back contact component. The insulating material is formed on part of the back light surface of the back contact cell. The method for determining the transparency of the insulating material comprises the following steps: obtaining the first spectral responsivity corresponding to a first region on the back light surface side of the back contact cell and the second spectral responsivity corresponding to a second region under the same incident wave band. The surface of the first region is covered with the insulating material, and the surface of the second region is not covered with the insulating material. Based on the wavelength range of the incident wave band, the first spectral responsivity and the second spectral responsivity, the transparency of the insulating material under the incident wave band is determined. The method for determining the bifaciality of the back contact component comprises the method for determining the transparency of the insulating material.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic cell technology, and in particular to a method for determining the transparency of an insulating material and the bifaciality of a back contact module. Background Technology

[0002] A back-contact solar cell refers to a solar cell where both the positive and negative electrodes are located on the back (or inside) of the cell, with no metal electrodes obstructing the front. Compared to photovoltaic cells with front-side shading, back-contact solar cells have higher short-circuit current and photoelectric conversion efficiency, making them one of the current technological directions for achieving high-efficiency crystalline silicon solar cells. Furthermore, in practical applications, the back surface of a back-contact solar cell is typically printed with insulating material to prevent the positive and negative electrodes from short-circuiting through the series interconnects, thus improving the electrical stability of the back-contact solar cell.

[0003] However, the aforementioned insulating materials have a certain degree of light-blocking properties, which can affect the light received by the back surface of the back-contact battery. Furthermore, photovoltaic engineers, when studying the bifaciality of back-contact batteries or modules, have not taken the light-blocking properties of the insulating materials into account, resulting in a significant difference between the calculated and measured values ​​of the bifaciality of the back-contact batteries or modules. Summary of the Invention

[0004] The purpose of this invention is to provide a method for determining the transparency of insulating materials and the bifaciality of back contact components, which is used to determine the transparency of insulating materials and improve the calculation accuracy of the bifaciality of back contact batteries or back contact components.

[0005] In a first aspect, the present invention provides a method for determining the transparency of an insulating material. The insulating material is formed on a portion of the back-facing surface of a back-contact battery.

[0006] The methods for determining the transparency of this insulating material include:

[0007] Under the same incident wavelength, the first spectral responsivity of a first region on the back side of the battery and the second spectral responsivity of a second region are obtained. The surface of the first region is covered with an insulating material, while the surface of the second region is not covered with an insulating material.

[0008] The transparency of the insulating material in the incident band is determined based on the wavelength range of the incident band, the first spectral responsivity, and the second spectral responsivity.

[0009] When the above technical solution is adopted, since the positive electrode and negative electrode of the back contact battery are both formed on the backlight surface, and in the process of connecting at least two back contact batteries in series to form a battery string through the in-string interconnect, the actual placement position of the in-string interconnect may be offset relative to the bus electrode connected to it. Therefore, forming an insulating material on a part of the back contact battery can prevent the positive electrode and negative electrode of the back contact battery from short-circuiting or opening through the in-string interconnect, thereby improving the electrical stability of the back contact battery.

[0010] Furthermore, in the actual determination process, the spectral responsivity of the back contact battery can be understood as its "transmittance" to light of different wavelengths. Therefore, when an insulating material is formed on the back surface of the back contact battery, the transparency of the insulating material under the incident wavelength can be obtained by acquiring and analyzing the first spectral responsivity corresponding to the first region covered by the insulating material and the second spectral responsivity corresponding to the second region not covered by the insulating material. In addition, acquiring the first and second spectral responsivity under the same incident wavelength can prevent the obtained first and second spectral responsivity from not only reflecting the light-blocking characteristics of the insulating material due to inconsistencies in the incident wavelength. This facilitates improving the accuracy of determining the transparency of the insulating material under the incident wavelength by controlling a single variable, thereby improving the accuracy of the bifaciality of the back contact battery or back contact assembly determined by the method of determining the transparency of the insulating material. This is of great significance for the design of back contact batteries or back contact assemblies, as it allows for obtaining high-precision bifaciality of the back contact battery or back contact assembly without actual measurement.

[0011] One possible approach is to obtain the first and second spectral responsivity using a quantum efficiency meter. In this case, the quantum efficiency meter can quickly and accurately obtain the first and second spectral responsivity, which is beneficial for further improving the accuracy of determining the transparency of the insulating material in the incident wavelength range.

[0012] As one possible implementation, the aforementioned quantum efficiency tester has a positive electrode and a negative electrode respectively connected to an adjacent positive bus electrode and a negative bus electrode in the back contact battery. Furthermore, both the first region and the second region are located within the collection range of the adjacent positive bus electrode and the negative bus electrode.

[0013] With the above technical solution, among all the positive and negative bus electrodes with opposite polarities included in the back contact battery, the resistance between an adjacent positive bus electrode and a negative bus electrode is the smallest. Based on this, when obtaining the first and second spectral responsivity using a quantum efficiency tester, if the positive and negative electrodes of the quantum efficiency tester are respectively connected to an adjacent positive and negative bus electrode in the back contact battery, and both the first and second regions are located within the collection range of the aforementioned adjacent positive and negative bus electrodes, then the influence of the back contact battery's own resistance on the results of obtaining the first and second spectral responsivity can be reduced during the acquisition process. This, in turn, helps to improve the accuracy of the transparency of the insulating material in the incident wavelength band determined based on the aforementioned first and second spectral responsivity.

[0014] As one possible implementation, the electrode pattern corresponding to the first region is the same as the electrode pattern corresponding to the second region.

[0015] When using the above technical solution, different electrode patterns may correspond to different light-shielding areas. Furthermore, all other things being equal, when different regions on the back side of the battery's back contact surface have electrode patterns with different light-shielding areas, the spectral responsivity of those regions may differ. In this case, when the electrode pattern corresponding to the first region is the same as the electrode pattern corresponding to the second region, it can prevent the obtained first and second spectral responsivity from not solely reflecting the light-shielding characteristics of the insulating material due to inconsistencies in the light-shielding areas of the electrode patterns corresponding to the first and second regions. This facilitates improving the accuracy of determining the transparency of the insulating material in the incident wavelength range by controlling a single variable.

[0016] As one possible implementation, the portion of the back contact battery located in the first region has the same film structure as the portion in the second region.

[0017] When employing the above technical solution, all other factors being equal, different regions of the back contact battery will exhibit different spectral responsivity when their film structures differ. In this case, the film structures of the portion of the back contact battery located in the first region and the portion in the second region are identical. This prevents the obtained first and second spectral responsivity from solely reflecting the light-shielding characteristics of the insulating material, thereby facilitating the improvement of the accuracy of determining the transparency of the insulating material in the incident wavelength range by controlling a single variable.

[0018] As one possible implementation, the wavelength range of the above-mentioned incident band is: greater than or equal to 300 nm and less than or equal to 1200 nm.

[0019] When using the above technical solution, existing back-contact batteries are typically silicon-based. Furthermore, the operating wavelength range of silicon-based back-contact batteries is generally greater than or equal to 300 nm and less than or equal to 1200 nm. In this case, when the wavelength range of the incident band for obtaining the first and second spectral responsivity is within this range, the test band for the transparency of the insulating material matches the operating band of the silicon-based back-contact battery. This facilitates the measurement of the transparency of the insulating material at the incident band based on the silicon-based back-contact battery, reducing the measurement difficulty.

[0020] As one possible implementation, the determination of the transparency of the insulating material in the incident band based on the wavelength range of the incident band, the first spectral responsivity, and the second spectral responsivity includes:

[0021] Based on the wavelength range of the incident band and the first spectral responsivity, the first short-circuit current density corresponding to the first region is determined.

[0022] Based on the wavelength range of the incident band and the second spectral responsivity, the second short-circuit current density corresponding to the second region is determined.

[0023] The ratio of the first short-circuit current density to the second short-circuit current density is the transparency of the insulating material in the incident wavelength band.

[0024] Using the above technical solution, the integral of the spectral responsivity with respect to wavelength equals the short-circuit current density of the back-contact battery, thus linking the optical and electrical characteristics of the back-contact battery. Based on this, after obtaining the first and second spectral responsivity, the first short-circuit current density corresponding to the first region can be determined based on the wavelength range of the incident band and the first spectral responsivity; and the second short-circuit current density corresponding to the second region can be determined based on the wavelength range of the incident band and the second spectral responsivity. Finally, the transparency of the insulating material in the incident band can be determined based on the ratio of the first short-circuit current density to the second short-circuit current density.

[0025] Secondly, the present invention also provides a method for determining the duplexity of a back contact assembly. The method for determining the duplexity of the back contact assembly includes:

[0026] Obtain the initial bifacial current ratio of the back contact battery without insulating material.

[0027] An insulating material is formed on a corresponding area of ​​the backlight surface of the back contact battery. The area ratio of the insulating material on the backlight surface is determined.

[0028] An encapsulating film and a glass cover are sequentially applied to both the light-facing and back-facing sides of the back-contact battery. A lamination process is then performed to obtain the back-contact assembly.

[0029] The transparency of the insulating material in the back contact assembly is obtained by using the method for determining the transparency of the insulating material provided by the first aspect and its various implementations.

[0030] Based on the structural correlation parameters of the bifacial current ratio of the back contact component, the spectral responsivity of the insulating material in the back contact component, and the area ratio of the insulating material on the back surface, the initial bifacial current ratio is corrected to obtain the bifacial current ratio of the back contact component.

[0031] The bifaciality of the back contact component is determined based on the bifacial current ratio of the back contact component.

[0032] Using the above technical solution, compared to back-contact assemblies, back-contact batteries without insulating material have a relatively simple structure, thus making it relatively easier to obtain the initial bifacial current ratio of such batteries. Next, by forming insulating material in the corresponding area of ​​the back-light side of the back-contact battery and laminating it, a back-contact assembly with the same usage state in practical applications but a relatively complex structure can be formed. The insulating material and other corresponding structures in the back-contact assembly have a certain influence on its bifacial current ratio. Therefore, by correcting the obtained initial bifacial current ratio based on the structural correlation parameters of the bifacial current ratio, the transparency of the insulating material in the back-contact assembly, and the area ratio of the insulating material on the back-light side, a high-precision bifacial current ratio for the back-contact assembly can be obtained. Based on this, since the bifaciality of the back contact assembly basically depends on the bifacial current ratio of the back contact assembly, the method for determining the bifaciality of the back contact assembly provided by the present invention can obtain a high-precision bifaciality of the back contact battery or back contact assembly without actual measurement, which is of great significance for the design of back contact batteries or back contact assemblies.

[0033] As one possible implementation, the aforementioned initial bifacial current ratio is the ratio of the short-circuit current density corresponding to the back-light side and the light-facing side of the back-contact battery without insulating material.

[0034] As one possible implementation, the structural correlation parameters of the bifacial current ratio of the back contact component include: the current loss ratio of the light-facing side of the back contact component, the current loss ratio of the back-light side of the back contact component, and the proportion of the newly added shading area on the back-light side of the back contact component.

[0035] In practical applications using the above technical solutions, back-contact batteries are typically connected in series, parallel, or a hybrid of series and parallel to form modules to meet the required current and voltage. However, due to the inconsistencies in the parameters of the back-contact batteries, the output power of the module after series and parallel connections may be less than the sum of the maximum output power of each individual back-contact battery. Specifically, when batteries are connected in series, the voltage across the terminals is the sum of the voltages of each individual battery, and the current is equal to the minimum current of each battery. When connected in parallel, the total current is the sum of the currents of each individual battery, and the voltage is the average value. Based on this, after back-contact batteries are laminated and packaged into back-contact modules, there will be current loss on both the light-facing and back-facing sides of the back-contact module. Furthermore, the back-facing side of the back-contact module has light-shielding structures such as bus electrodes, intra-series interconnects, frames, and junction boxes, which also affect the bifacial current ratio of the back-contact module. In this case, when the structural correlation parameters of the bifacial current ratio of the back contact component include the current loss ratio of the light-facing side of the back contact component, the current loss ratio of the back-light side of the back contact component, and the proportion of the newly added shading area of ​​the back-light side of the back contact component, the accuracy of correcting the initial bifacial current ratio based on the structural correlation parameters can be improved, and the accuracy of determining the bifacial current ratio and bifaciality of the back contact component can be further improved.

[0036] As one possible implementation, the glass cover plate is provided with an enamel coating. In this case, the structural correlation parameters of the bifacial current ratio of the back contact assembly also include the light gain of the enamel coating on the light-emitting surface and the light gain of the enamel coating on the back light-emitting surface.

[0037] By employing the above technical solution, an enamel layer is applied to the glass cover plate to shield structures such as busbars in the back contact assembly, ensuring that the overall color of the back contact assembly meets the requirements of the application scenario. Simultaneously, it also helps improve the structural strength of the back contact assembly. In practical applications, this enamel layer has a certain reflective ability, thus providing a certain light gain to both the light-facing and back-facing sides of the back contact assembly, which helps improve the light utilization rate of the back contact assembly. In this case, when the structural correlation parameters of the bifacial current ratio of the back contact assembly also include the light gain of the enamel layer on the light-facing side and the light gain of the enamel layer on the back-facing side, the light reception of both the light-facing and back-facing sides of the back contact assembly can be comprehensively considered, further improving the accuracy of correcting the initial bifacial current ratio based on these structural correlation parameters, and improving the accuracy of determining the bifacial current ratio and bifaciality of the back contact assembly.

[0038] As one possible implementation, the formula for calculating the bifacial current ratio of the back contact component is:

[0039]

[0040] Where k is the initial bifacial current ratio, α is the current loss ratio of the light-facing side of the back contact component, β is the current loss ratio of the back-facing side of the back contact component, a is the proportion of the newly added light-shielding area of ​​the back-facing side of the back contact component, δ is the light gain of the enamel layer to the light-facing side, b is the area ratio of the enamel layer on the back-facing side to the enamel layer on the light-facing side, c is the area ratio of the insulating material on the back-facing side, and n is the transparency of the insulating material in the back contact component. Attached Figure Description

[0041] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0042] Figure 1 A schematic diagram of the back surface structure of a back contact battery with insulating material is shown.

[0043] Figure 2 A flowchart illustrating the method for determining the transparency of insulating materials provided in an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of obtaining the first spectral responsivity corresponding to the first region in the back contact battery using a quantum efficiency tester;

[0045] Figure 4 This is a schematic diagram of obtaining the first spectral responsivity corresponding to the second region in the back contact battery using a quantum efficiency tester;

[0046] Figure 5 This is a schematic diagram of the first and second spectral responsivity when the insulating material in the back contact battery is green (referred to as green adhesive in the figure);

[0047] Figure 6 This is a schematic diagram of the first and second spectral responsivity when the insulating material in the back contact battery is white (referred to as white glue in the figure);

[0048] Figure 7 A flowchart illustrating the method for determining the duplexity of a back contact assembly according to an embodiment of the present invention;

[0049] Figure 8 This is a schematic diagram showing the acquisition of the first spectral responsivity of the first region in the back contact assembly using a quantum efficiency tester.

[0050] Figure 9 This is a schematic diagram showing the acquisition of the first spectral responsivity corresponding to the second region in the back contact assembly using a quantum efficiency tester.

[0051] Figure 10This is a schematic diagram of the first and second spectral responsivity when the insulating material in the back contact assembly is green (referred to as green adhesive in the figure).

[0052] The attached diagram is labeled as follows: 1 is the positive electrode, 2 is the negative electrode, 3 is the bus electrode, 4 is the current collector electrode, 5 is the current collector electrode segment, and 6 is the insulating material. Detailed Implementation

[0053] To facilitate a clear description of the technical solutions in the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish identical or similar items with essentially the same function and effect. For example, the first threshold and the second threshold are only used to distinguish different thresholds and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" are not necessarily different.

[0054] It should be noted that, in this application, the terms "exemplary" or "for example" are used to indicate that something is being described as an example, illustration, or illustration. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0055] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can mean: a, b, c, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple.

[0056] A back-contact solar cell refers to a solar cell where both the positive and negative electrodes are located on the back side of the cell, with no metal electrodes obstructing the front. Compared to solar cells with front-side shading, back-contact solar cells have higher short-circuit current and photoelectric conversion efficiency, making them one of the current technological directions for achieving high-efficiency crystalline silicon solar cells. Furthermore, in practical applications, the back side of a back-contact solar cell is typically printed with insulating material to prevent the positive and negative electrodes from short-circuiting through the series interconnects, thus improving the electrical stability of the back-contact solar cell.

[0057] However, the aforementioned insulating materials possess a certain degree of light-blocking property, which can affect the light reception on the back side of the back contact battery. Traditionally, the primary application of insulating materials is in the electronics industry. Furthermore, the electronics industry generally focuses on evaluating the insulation or solderability of insulating materials, with little mention of their transparency. Even for photocurable insulating materials, those skilled in the art primarily study their absorption characteristics in the UV band. Additionally, photovoltaic engineers, when studying the bifaciality of back contact batteries or modules, have not considered the light-blocking property of the insulating materials, resulting in significant discrepancies between calculated and measured values. This hinders accurate prediction of the power generation of back contact modules and makes it difficult to guide the design of back contact batteries without actual measurements.

[0058] To address the aforementioned technical problems, in a first aspect, embodiments of the present invention provide a method for determining the transparency of an insulating material. The insulating material is formed on a portion of the back-facing surface of a battery.

[0059] Specifically, since both the positive and negative electrodes of the back contact battery are formed on the backlight surface, and during the process of connecting at least two back contact batteries in series to form a battery string using interconnecting elements, the actual placement position of the interconnecting elements may shift relative to the connected bus electrode. Therefore, forming an insulating material on a portion of the back contact battery can prevent the positive and negative electrodes from short-circuiting or opening through the interconnecting elements, thus improving the electrical stability of the back contact battery. Based on this, the specific area of ​​the insulating material formed on the backlight surface of the back contact battery can be determined according to the specific structure of the positive and negative electrodes included in the back contact battery, as well as the placement accuracy of the interconnecting elements; no specific limitation is made here.

[0060] For example: Figure 1 As shown, the back contact battery includes a positive electrode 1 and a negative electrode 2, each comprising multiple current collector electrodes 4 and multiple current collector electrodes 3. The multiple current collector electrodes 4 of both the positive electrode 1 and the negative electrode 2 extend along a first direction and are alternately spaced along a second direction. The first direction is different from the second direction. The multiple current collector electrodes 3 of both the positive electrode 1 and the negative electrode 2 extend along the second direction and are alternately spaced along the first direction. Each current collector electrode 3 is connected to all current collector electrodes 4 of the same polarity. Furthermore, each current collector electrode 4 includes multiple current collector segments 5 spaced apart along the first direction, and the gap between adjacent current collector segments 5 of the same current collector electrode 4 serves to isolate current collector electrodes 3 of opposite polarity. In this case, the insulating material 6 may only cover the end of each current collector segment 5 near the current collector electrode 3 of opposite polarity.

[0061] Specifically, such as Figure 2 As shown, the method for determining the transparency of the above-mentioned insulating material includes the following steps:

[0062] Step S101: Obtain the first spectral responsivity of the first region and the second spectral responsivity of the second region on the back side of the back contact battery under the same incident wavelength. The surface of the first region is covered with insulating material, while the surface of the second region is not covered with insulating material.

[0063] Specifically, the wavelength range of the aforementioned incident band can be set according to actual needs, as long as it can be applied to the method for determining the transparency of insulating materials provided in this embodiment of the invention. For example, the wavelength range of the aforementioned incident band can be greater than or equal to 300 nm and less than or equal to 1200 nm. In this case, existing back contact batteries are typically silicon-based back contact batteries. Furthermore, the operating wavelength range of silicon-based back contact batteries is approximately greater than or equal to 300 nm and less than or equal to 1200 nm. Based on this, when the wavelength range of the incident band for obtaining the first and second spectral responsivity is within this range, the test band for the transparency of the insulating material matches the operating band of the silicon-based back contact battery, facilitating the measurement of the transparency of the insulating material under the incident band based on the silicon-based back contact battery and reducing the measurement difficulty.

[0064] Regarding the first and second regions mentioned above, the first region can be any region located on the back side of the battery that is in contact with the back and covered with insulating material. For example: Figure 1 As shown, the first region can be the end region of each current collector segment 5 near the bus electrode 3 with the opposite polarity. The second region can be any region located on the back side of the battery that is not covered with insulating material. For example: Figure 1 As shown, the first region can be the central region of each current collector electrode segment 5. The extent of the first and second regions can be determined according to the actual application scenario, and is not specifically limited here. The shape and area of ​​the first and second regions can be the same or different.

[0065] In practical applications, the first and second spectral responsivities can be obtained using devices such as quantum efficiency testers, spectral response testers, or photodetectors. Among these, quantum efficiency testers can quickly and accurately obtain the first and second spectral responsivities, which is beneficial for further improving the accuracy of determining the transparency of insulating materials in the incident wavelength range.

[0066] The following explanation uses the acquisition of the first and second spectral responsivity using a quantum efficiency meter as an example: The operating wavelength of the quantum efficiency meter is set, and the positive and negative electrodes of the meter are connected in series with a positive bus electrode and a negative bus electrode of the back contact battery via interconnects such as solder ribbons, thus connecting the quantum efficiency meter in series with the back contact battery. Next, the quantum efficiency meter is activated, and the spectral probe is irradiated onto the surface of the first region. As the wavelength varies within the corresponding incident wavelength range, the first spectral responsivity corresponding to the first region is obtained. The same method is then used, and the second spectral responsivity corresponding to the second region is obtained under the same incident wavelength.

[0067] The specific relative positions of the positive and negative bus electrodes in the back contact battery, which are connected to the positive and negative electrodes of the quantum efficiency tester, can be determined according to actual needs. Specifically, for example... Figure 3 and Figure 4 As shown, one adjacent positive bus electrode and one negative bus electrode in the back-contact battery can be connected to the positive and negative electrodes of the quantum efficiency tester, respectively. For example: Figure 1 As shown, the first positive bus electrode and the first negative bus electrode, counting from left to right, can be connected to the positive and negative electrodes of the quantum efficiency tester, respectively. Alternatively, a positive bus electrode and a negative bus electrode, spaced apart from each other in the back contact battery, can be connected to the positive and negative electrodes of the quantum efficiency tester, respectively. For example: Figure 1 As shown, the first positive bus electrode and the third negative bus electrode, counting from left to right, can be connected to the positive and negative electrodes of the quantum efficiency tester, respectively.

[0068] It is worth noting that among all the positive and negative bus electrodes with opposite polarities in a back-contact battery, the resistance between an adjacent positive and negative bus electrode is the lowest. Based on this, when obtaining the first and second spectral responsivity using a quantum efficiency meter, such as... Figure 3 and Figure 4 As shown, if the positive and negative electrodes of the quantum efficiency tester are respectively connected to an adjacent positive bus electrode and a negative bus electrode in the back contact battery, and the first region and the second region are both located within the collection range of the aforementioned adjacent positive bus electrode and negative bus electrode, then the influence of the back contact battery's own resistance on the acquisition results of the first and second spectral responsivity can be reduced during the acquisition process, thereby improving the accuracy of the transparency of the insulating material in the incident band determined based on the aforementioned first and second spectral responsivity.

[0069] Step S102: Determine the transparency of the insulating material in the incident band based on the wavelength range of the incident band, the first spectral responsivity, and the second spectral responsivity.

[0070] In the actual determination process, the spectral responsivity of the back contact battery can be understood as its "transmittance" to light of different wavelengths. Therefore, when an insulating material is formed on the back surface of the back contact battery, the transparency of the insulating material in the incident wavelength can be obtained by acquiring and analyzing the first spectral responsivity corresponding to the first region covered by the insulating material on one side of the back surface of the back contact battery and the second spectral responsivity corresponding to the second region not covered by the insulating material.

[0071] For example, determining the transparency of the insulating material under the incident wavelength band based on the wavelength range of the incident band, the first spectral responsivity, and the second spectral responsivity may include the following steps: determining a first short-circuit current density corresponding to a first region based on the wavelength range of the incident band and the first spectral responsivity; and determining a second short-circuit current density corresponding to a second region based on the wavelength range of the incident band and the second spectral responsivity. Finally, the ratio of the first short-circuit current density to the second short-circuit current density is the transparency of the insulating material under the incident wavelength band.

[0072] Specifically, the formula for calculating the transparency of the aforementioned insulating material in the incident wavelength band is as follows:

[0073]

[0074] Where T is the transparency of the insulating material in the incident wavelength range. (λ1, λ2) are the wavelength range of the incident wavelength range. S'(λ) is the first spectral responsivity. S(λ) is the second spectral responsivity.

[0075] Using the above technical solution, the integral of the spectral responsivity with respect to wavelength equals the short-circuit current density of the back-contact battery, thus linking the optical and electrical characteristics of the back-contact battery. Based on this, after obtaining the first and second spectral responsivity, the first short-circuit current density corresponding to the first region can be determined based on the wavelength range of the incident band and the first spectral responsivity; and the second short-circuit current density corresponding to the second region can be determined based on the wavelength range of the incident band and the second spectral responsivity. Finally, the transparency of the insulating material in the incident band can be determined based on the ratio of the first short-circuit current density to the second short-circuit current density.

[0076] It should be noted that, as mentioned above, the areas of the first region and the second region can be equal or different. Specifically, when the areas of the first region and the second region are equal, the spectral responsivity of the insulating material in the incident wavelength band is also equal to the ratio of the short-circuit current corresponding to the first region to the short-circuit current corresponding to the second region.

[0077] As can be seen from the above, the method for determining the transparency of insulating materials provided in this embodiment of the invention first obtains the first spectral responsivity and the second spectral responsivity under the same incident wavelength. This can prevent the obtained first and second spectral responsivity from not only reflecting the light-blocking characteristics of the insulating material due to inconsistencies in the incident wavelength. This facilitates the improvement of the accuracy of determining the transparency of the insulating material under the incident wavelength by controlling a single variable. As a result, the accuracy of the bifaciality of the back contact battery or back contact assembly determined by this method for determining the transparency of the insulating material can be improved. This is of great significance for the design of back contact batteries or back contact assemblies, as it allows for obtaining high-precision bifaciality of the back contact battery or back contact assembly without actual measurement.

[0078] Among them, such as Figure 5 and Figure 6 As shown, the transparency of insulating materials is related to the chemical composition of the pigments, and the spectral absorption peaks of pigments of different colors are not entirely the same. For example, when the insulating material is green, it has a strong absorption rate in both the UV and infrared bands, and its spectral response curve is shown in the figure. Figure 5 As shown. The ratio of the integrals of the two along the wavelength is the transparency of the green insulating material, which is approximately 46.5%. For example: Figure 6 As shown, when the insulating material is white, its main absorption peak is located in the UV band, and the shape of its spectral response curve in the visible and near-UV bands is close to the second spectral responsivity corresponding to the second region. The ratio of the integrals of the two over wavelengths is the transparency of the white insulating material, which is approximately 28.0%. Furthermore, based on the requirements for the type of back-contact module in actual application scenarios (black module / white module / double-glass module / invisible module / building-integrated photovoltaic module), the type of insulating material suitable for different types or application scenarios can be inferred by measuring the transparency of the insulating material. For example, for black modules, invisible modules, and building-integrated photovoltaic modules, the transparency requirement for the insulating material inside the module is relatively low; these modules primarily aim to reduce heat loss during power generation and improve module lifespan. White modules and double-glass modules, on the other hand, require higher transparency of the insulating material to ensure better power generation. Based on this, the method for determining the transparency of insulating materials provided in this embodiment of the invention has high determination accuracy, making it easy to obtain the transparency of each type of insulating material. This allows for precise guidance on the types of insulating materials suitable for different types of back contact components, enabling the bifacial output power ratio of the back contact component to leverage the natural advantages of the back contact battery as a bifacial battery.

[0079] In practical applications, both the positive and negative electrodes of the back-contact battery are formed on the back-side of the light-reflecting surface. Furthermore, the positive and negative electrodes, made of a metallic conductive material, possess complete light-shielding properties. Based on this, when obtaining the first and second spectral responsivity, the electrode patterns corresponding to the first and second regions are identical. In this case, the light-shielding areas of the corresponding electrode patterns in the first and second regions are the same, preventing the obtained first and second spectral responsivity from not solely reflecting the light-shielding characteristics of the insulating material due to inconsistencies in the light-shielding areas of the electrode patterns in the first and second regions. This facilitates improving the accuracy of determining the transparency of the insulating material in the incident wavelength range by controlling a single variable.

[0080] It should be noted that when the effective top surface area of ​​the electrode patterns corresponding to the first and second regions is the same, the light-blocking area of ​​the electrode patterns corresponding to the first and second regions is the same. Accordingly, the influence of the electrode patterns of the first and second regions on the spectral responsivity of the back contact battery and the transparency of the insulating material can be suppressed.

[0081] Furthermore, all other things being equal, when the film structure differs in different regions on the back side of the back contact battery, the corresponding spectral responsivity varies. Therefore, when obtaining the first and second spectral responsivity, the selected first and second regions should have the same film structure for the portion of the back contact battery located in the first region and the portion in the second region. This prevents the obtained first and second spectral responsivity from solely reflecting the light-shielding characteristics of the insulating material, thus facilitating the improvement of the accuracy of determining the transparency of the insulating material in the incident wavelength range by controlling a single variable.

[0082] Secondly, embodiments of the present invention also provide a method for determining the duplexity of a back contact assembly. For example... Figure 7 As shown, the method for determining the bifaciality of the back contact assembly includes the following steps:

[0083] Step S201: Obtain the initial bifacial current ratio of the back contact battery without insulating material.

[0084] Specifically, the aforementioned initial bifacial current ratio can be the ratio of the short-circuit current density corresponding to the back-lighting side and the light-facing side of the back-contact battery without insulating material. Alternatively, when obtaining the bifacial current ratio of the back-lighting side and the light-facing side of the back-contact battery without insulating material, if the selected areas are the same, the aforementioned initial bifacial current ratio can also be the ratio of the short-circuit current corresponding to the back-lighting side and the light-facing side of the back-contact battery without insulating material.

[0085] In practical applications, as mentioned earlier, the integral of the spectral responsivity over the incident band equals the short-circuit current density. Therefore, using devices capable of measuring spectral responsivity, such as quantum efficiency meters, spectral response meters, or photodetectors, we can first obtain the spectral responsivity of the back-side and light-facing sides of a back-contact battery without insulating material under the same incident band. Then, by calculating the integral of the spectral responsivity over the incident band, we can obtain the short-circuit current density corresponding to the back-side and light-facing sides of the back-contact battery without insulating material. Finally, dividing the short-circuit current density of the back-side and light-facing sides of the back-contact battery without insulating material by the ratio yields the initial bifacial current ratio.

[0086] Step S202: Form an insulating material on the corresponding area of ​​the backlight surface of the back contact battery. Determine the area ratio of the insulating material on the backlight surface.

[0087] Specifically, insulating material can be formed on the corresponding area of ​​the back surface of the back contact battery using methods such as inkjet printing, coating, or screen printing. The extent of this insulating material formation on the back surface of the back contact battery can be referred to the previous text and will not be repeated here.

[0088] Step S203: Sequentially apply an encapsulating film and a glass cover to both the light-facing and back-facing sides of the back contact battery; and perform lamination to obtain the back contact assembly.

[0089] Specifically, the materials of the encapsulating film and the glass cover, as well as the structure of the glass cover, can be set according to the actual application scenario, and are not specifically limited here. The glass cover may or may not have an enamel coating. When an enamel coating is applied to the glass cover, it can shield structures such as busbars in the back contact assembly, ensuring that the overall color of the back contact assembly meets the requirements of the application scenario. It also helps to improve the structural strength of the back contact assembly. In practical applications, the enamel coating has a certain reflective ability, thus providing a certain light gain to both the light-facing and back-facing sides of the back contact assembly, which helps to improve the light utilization rate of the back contact assembly.

[0090] Step S204: As Figure 8 and Figure 9 As shown, the transparency of the insulating material in the back contact assembly is obtained by using the method for determining the transparency of the insulating material provided by the first aspect and its various implementations.

[0091] Specifically, firstly, the first spectral responsivity of a first region and the second spectral responsivity of a second region on one side of the back contact component are obtained under the same incident wavelength. The surface of the first region is covered with an insulating material, while the surface of the second region is not covered with an insulating material. Next, based on the wavelength range of the incident wavelength, the first spectral responsivity, and the second spectral responsivity, the transparency of the insulating material in the back contact component can be obtained.

[0092] It is understandable that the back-side of the back contact component not only has an insulating material but also an encapsulating film and a glass cover. Therefore, the result obtained using the above method is the total transparency of the insulating material, encapsulating film, and glass cover. For example, the transparency of the green insulating material in the back contact component is as follows: Figure 10 As shown. The ratio of the integrals of the two over wavelengths represents the transparency of the green insulating material in the back contact assembly, which is approximately 44.3%.

[0093] Step S205: Based on the structural correlation parameters of the bifacial current ratio of the back contact component, the transparency of the insulating material in the back contact component, and the area ratio of the insulating material on the back light surface, the initial bifacial current ratio is corrected to obtain the bifacial current ratio of the back contact component.

[0094] Specifically, the structural correlation parameters of the bifacial current ratio of the aforementioned back contact component can include any parameter that affects the light reception of the light-facing and back-facing surfaces of the back contact component.

[0095] For example, when the glass cover of the back contact assembly does not have an enamel coating, the structural parameters related to the bifacial current ratio of the back contact assembly can include: the current loss ratio of the light-facing side of the back contact assembly, the current loss ratio of the back-light-facing side of the back contact assembly, and the proportion of newly added shading area on the back-light-facing side of the back contact assembly. In this case, in practical applications, back contact batteries are usually connected in series, parallel, or a hybrid series-parallel configuration to form an assembly to meet the required current and voltage. However, due to the inconsistency of the parameters of the back contact batteries, the output power of the assembly after series and parallel connection may be less than the sum of the maximum output power of each individual back contact battery. Specifically, when the batteries are connected in series, the voltage across the terminals is the sum of the voltages of each individual battery, and the current is equal to the minimum current of each battery. When connected in parallel, the total current is the sum of the currents of each individual battery, and the voltage is the average value. Based on this, after laminating and encapsulating the back contact batteries with insulating material into a back contact assembly, there will be current loss on both the light-facing and back-light-facing sides of the back contact assembly. Furthermore, the back surface of the back contact assembly contains light-shielding structures such as bus electrodes, interconnects, frames, and junction boxes, which also affect the bifacial current ratio of the back contact assembly. In this case, when the structural correlation parameters of the bifacial current ratio of the back contact assembly include the current loss ratio of the light-facing side of the back contact assembly, the current loss ratio of the back-facing side of the back contact assembly, and the proportion of newly added light-shielding area on the back-facing side of the back contact assembly, the accuracy of correcting the initial bifacial current ratio based on these structural correlation parameters can be improved, further enhancing the accuracy of determining the bifacial current ratio and bifaciality of the back contact assembly.

[0096] When the aforementioned glass cover plate is provided with an enamel layer, the structural correlation parameters of the bifacial current ratio of the back contact assembly can also include the light gain of the enamel layer on the light-facing side and the light gain of the enamel layer on the back-facing side. In this case, as mentioned above, the enamel layer has a certain reflective ability, thus providing a certain light gain to both the light-facing and back-facing sides of the back contact assembly. Based on this, when the structural correlation parameters of the bifacial current ratio of the back contact assembly also include the light gain of the enamel layer on the light-facing side and the light gain of the enamel layer on the back-facing side, the light reception of both the light-facing and back-facing sides of the back contact assembly can be comprehensively considered, further improving the accuracy of correcting the initial bifacial current ratio based on these structural correlation parameters, and improving the accuracy of determining the bifacial current ratio and bifaciality of the back contact assembly.

[0097] In practical applications, after obtaining the structural correlation parameters of the bifacial current ratio of the back contact component, the transparency of the insulating material in the back contact component, and the area ratio of the insulating material on the back surface, it is necessary to correct the initial bifacial current ratio so that the final determined bifacial current ratio of the back contact component can accurately represent the measured value of the bifacial current ratio of the back contact component. Specifically, the calculation method of the above correction process can be determined according to the types of parameters included in the structural correlation parameters of the bifacial current ratio of the back contact component.

[0098] For example, when the structurally related parameters of the bifacial current ratio of the back contact assembly include: the current loss ratio of the light-facing side of the back contact assembly, the current loss ratio of the back-light-facing side of the back contact assembly, the proportion of the newly added light-shielding area of ​​the back-light-facing side of the back contact assembly, the light gain of the enamel layer on the light-facing side, and the light gain of the enamel layer on the back-light-facing side, the calculation formula for the bifacial current ratio of the back contact assembly can be:

[0099]

[0100] Where k is the initial bifacial current ratio, α is the current loss ratio of the light-facing side of the back contact component, β is the current loss ratio of the back-facing side of the back contact component, a is the proportion of the newly added light-shielding area of ​​the back-facing side of the back contact component, δ is the light gain of the enamel layer to the light-facing side, b is the area ratio of the enamel layer on the back-facing side to the enamel layer on the light-facing side, c is the area ratio of the insulating material on the back-facing side, and n is the transparency of the insulating material in the back contact component.

[0101] Step S206: Determine the bifaciality of the back contact battery based on the bifacial current ratio of the back contact assembly.

[0102] In practical applications, the bifaciality of a back-contact battery is basically determined by its bifacial current ratio. Therefore, after obtaining the bifacial current ratio of the back-contact battery using the above method, the bifaciality of the back-contact battery can be determined.

[0103] Table 1 shows the testing of back contact assemblies made from three back contact batteries with similar working efficiency, and compares the parameters of the three back contact assemblies.

[0104] Table 1: Comparison of parameters of the three back contact components

[0105]

[0106] As can be seen from the data in Table 1 above, when calculating the bifacial current ratio of modules 1 and 2, the influence of structural parameters on the bifacial current ratio was considered, as well as the influence of the insulation material. Therefore, the differences between the calculated and measured bifacial current ratios of modules 1 and 2, and the differences between the calculated and measured bifacial ratios, are relatively small (reduced to within 0.2%). However, module 3 only considered the influence of structural parameters on the bifacial current ratio and treated the insulation material as completely transparent. Therefore, the differences between the calculated and measured bifacial current ratios of module 3, and the differences between the calculated and measured bifacial ratios, are relatively large.

[0107] As can be seen from the above, compared with back-contact assemblies, back-contact batteries without insulating material have a relatively simple structure, thus obtaining the initial bifacial current ratio of such batteries is relatively easier. Next, by forming insulating material in the corresponding area of ​​the back-light side of the back-contact battery and laminating it, a relatively complex back-contact assembly can be formed. The insulating material and other corresponding structures in the back-contact assembly have a certain influence on the bifacial current ratio. Therefore, by correcting the initial bifacial current ratio based on the structural correlation parameters of the bifacial current ratio, the transparency of the insulating material in the back-contact assembly, and the area ratio of the insulating material on the back-light side, a high-precision bifacial current ratio of the back-contact assembly can be obtained. Based on this, since the bifaciality of a back-contact assembly basically depends on its bifacial current ratio, the method for determining the bifaciality of a back-contact assembly provided in this embodiment of the invention can achieve a high-precision bifaciality of the back-contact battery or assembly without actual measurement, which is of great significance for the design of back-contact batteries or assemblies.

[0108] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed invention. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0109] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A method for determining the transparency of an insulating material, characterized in that, The insulating material is formed on a portion of the back surface of the battery. The method for determining the transparency of the insulating material includes: Under the same incident wavelength, the first spectral responsivity corresponding to the first region on one side of the back contact battery and the second spectral responsivity corresponding to the second region are obtained; the surface of the first region is covered with the insulating material, and the surface of the second region is not covered with the insulating material. The transparency of the insulating material in the incident band is determined based on the wavelength range of the incident band, the first spectral responsivity, and the second spectral responsivity. The determination of the transparency of the insulating material in the incident wavelength band, based on the wavelength range of the incident band, the first spectral responsivity, and the second spectral responsivity, includes: Based on the wavelength range of the incident band and the first spectral responsivity, the first short-circuit current density corresponding to the first region is determined; Based on the wavelength range of the incident band and the second spectral responsivity, the second short-circuit current density corresponding to the second region is determined; The ratio of the first short-circuit current density to the second short-circuit current density is the transparency of the insulating material in the incident wavelength band.

2. The method for determining the transparency of an insulating material according to claim 1, characterized in that, The first spectral responsivity and the second spectral responsivity were obtained using a quantum efficiency tester.

3. The method for determining the transparency of an insulating material according to claim 2, characterized in that, The quantum efficiency tester has a positive electrode and a negative electrode that are respectively connected to an adjacent positive bus electrode and a negative bus electrode in the back contact battery. Both the first region and the second region are located within the collection range of the adjacent positive bus electrode and negative bus electrode.

4. The method for determining the transparency of an insulating material according to claim 1, characterized in that, The electrode pattern corresponding to the first region is the same as the electrode pattern corresponding to the second region; and / or, The portion of the back contact battery located in the first region has the same film structure as the portion in the second region.

5. The method for determining the transparency of an insulating material according to claim 1, characterized in that, The wavelength range of the incident band is greater than or equal to 300 nm and less than or equal to 1200 nm.

6. A method for determining the bifaciality of a back contact assembly, characterized in that, include: Obtain the initial bifacial current ratio of the back contact battery without insulating material; An insulating material is formed on a corresponding area of ​​the back surface of the back contact battery; And determine the area ratio of the insulating material on the backlight surface; An encapsulating film and a glass cover are sequentially applied to both the light-facing side and the back-light-facing side of the back contact battery; and a lamination process is performed to obtain a back contact assembly; an enamel coating is provided on the glass cover. The transparency of the insulating material in the back contact assembly is obtained by using the method for determining the transparency of the insulating material according to any one of claims 1 to 5. Based on the structural correlation parameters of the bifacial current ratio of the back contact assembly, the transparency of the insulating material in the back contact assembly, and the area ratio of the insulating material on the backlight surface, the initial bifacial current ratio is corrected to obtain the bifacial current ratio of the back contact assembly. The bifaciality of the back contact battery is determined based on the bifacial current ratio of the back contact assembly. The structural correlation parameters of the bi-sided current ratio of the back contact component include: the current loss ratio of the light-facing side of the back contact component, the current loss ratio of the back-light side of the back contact component, and the proportion of the newly added shading area of ​​the back-light side of the back contact component. The structural correlation parameters of the bi-sided current ratio of the back contact assembly also include the light gain of the enamel layer facing the light surface and the light gain of the enamel layer facing the back light surface. The formula for calculating the bifacial current ratio of the back contact assembly is as follows: ； Wherein, γ is the bifacial current ratio of the back contact battery, k is the initial bifacial current ratio, α is the current loss ratio of the light-facing side of the back contact assembly, β is the current loss ratio of the back-light-facing side of the back contact assembly, a is the proportion of the newly added light-shielding area on the back-light-facing side of the back contact assembly, δ is the light gain of the enamel layer on the light-facing side, b is the area ratio of the enamel layer on the back-light-facing side to the enamel layer on the light-facing side, c is the area ratio of the insulating material on the back-light-facing side, and n is the transparency of the insulating material in the back contact assembly.

7. The method for determining the bifaciality of the back contact assembly according to claim 6, characterized in that, The initial bifacial current ratio is the ratio of the short-circuit current density corresponding to the back-light side and the light-facing side of the back contact battery that has not formed an insulating material.

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