A half-cut photovoltaic module and a method of manufacturing the same

Abstract

The application discloses a kind of half piece photovoltaic module and its preparation method, it is related to photovoltaic module preparation technical field, method includes: selecting whole piece cell piece, and the efficiency and / or open circuit voltage of whole piece cell piece are tested and graded;Whole piece cell piece is cut into half piece cell piece;PL test is carried out to half piece cell piece, and grading is carried out according to the gray mean of PL image;Half piece cell piece of same efficiency grade and / or same open circuit voltage grade and same PL gray mean grade is arranged in same half piece photovoltaic module, and the preparation of half piece photovoltaic module is completed.The application adopts the efficiency and / or open circuit voltage grading of whole piece cell piece to combine the PL gray mean grading of half piece cell piece, simple operation can effectively reduce EL light and shade bad.

Description

Technical Field

[0001] This application relates to the field of photovoltaic module manufacturing technology, and in particular to a half-cell photovoltaic module and its manufacturing method. Background Technology

[0002] Half-cell solar cells are widely used in photovoltaic (PV) modules due to their ability to reduce series resistance. Poor EL (electroluminescence) brightness is a common defect in PV modules, significantly impacting their performance and lifespan. It can lead to a decrease in the overall photoelectric conversion efficiency, preventing the module from fully utilizing light energy and resulting in energy loss. Furthermore, poor EL brightness can accelerate module aging and damage; localized overheating and current concentration can cause degradation of internal materials, even triggering hot spot effects, and in severe cases, potentially causing module burnout.

[0003] Patent CN118763016B discloses a method for reducing EL (Elasticity and Lightness) defects in photovoltaic (PV) modules and a PV module itself. The method primarily involves testing the solar cells using photoluminescence (PL) images and analyzing the uniformity of these PL images to classify the cells, thereby reducing EL defects. While this method has some effect on whole PV modules, it is computationally complex, requiring the division of each cell into regions and the calculation of grayscale uniformity within each region. Furthermore, for half-cell PV modules, since the half-cells are laser-cut from whole cells, the cutting process damages the cells. If these half-cells are not sorted and directly placed in the same PV module, the EL defects remain extremely high. Summary of the Invention

[0004] This application aims to solve one of the above-mentioned problems. This application provides a half-cell photovoltaic module and its fabrication method, which can effectively reduce EL brightness and darkness defects. Specifically, the first aspect of this application provides a method for fabricating a half-cell photovoltaic module, the method comprising: Select whole solar cells and test and classify the efficiency and / or open-circuit voltage of the whole solar cells; The whole battery cell is cut into half battery cells; The half-cell battery cell is subjected to PL testing, and the cells are classified according to the average grayscale value of the PL image. The half-cell solar cells with the same efficiency level and / or the same open-circuit voltage level and the same PL grayscale average level are arranged in the same half-cell photovoltaic module to complete the fabrication of the half-cell photovoltaic module.

[0005] This application adopts the efficiency and / or open-circuit voltage classification of the whole cell combined with the PL grayscale average value classification of the half cell to limit the efficiency difference and / or open-circuit voltage difference and PL grayscale average value difference within the half cell photovoltaic module to a specific range, effectively reducing EL brightness and darkness defects. Moreover, it is simple to operate, does not require complicated calculations, and effectively reduces the manufacturing cost of half cell photovoltaic modules.

[0006] Optionally, the efficiency difference of the entire solar cell within the same efficiency range is no greater than 0.2%; and / or, the open-circuit voltage difference of the entire solar cell within the same open-circuit voltage range is no greater than 6mV; and / or, the difference in the average grayscale value of the half-cell within the same PL grayscale value range is no greater than 30. By further improving the grading accuracy, the stability and controllability of the manufacturing process are enhanced.

[0007] Preferably, the difference in the average grayscale value of the half-cells at the same PL grayscale average value level is no greater than 10.

[0008] Optionally, the difference in efficiency threshold between adjacent efficiency levels is not less than 0.1%; and / or, the difference in open-circuit voltage threshold between adjacent open-circuit voltage levels is not less than 4mV; and / or, the difference in grayscale average threshold between adjacent PL grayscale average levels is not less than 5.

[0009] Optionally, based on the PL grayscale mean threshold, the PL grayscale mean is divided into n levels, where n≥2. For the same efficiency level, the grayscale mean thresholds for the same PL grayscale mean level are different for half-cells with different open-circuit voltage levels; wherein, the PL grayscale mean threshold of the i-th level of the low open-circuit voltage level is less than the PL grayscale mean threshold of the i-th level of the high open-circuit voltage level; i is any integer between 1 and n. By optimizing the adaptation method between high open-circuit voltage and PL grayscale mean, the matching degree of cells within the module is further improved, effectively suppressing EL brightness defects.

[0010] Preferably, for the same efficiency level, the difference in the average grayscale threshold of PL for the i-th level of adjacent open-circuit voltage levels of the half-cells is not less than 5.

[0011] Optionally, based on the PL grayscale average value threshold, the PL grayscale average value is divided into n levels, where n≥2. For the same open-circuit voltage level, the grayscale average value thresholds of the same PL grayscale average value level are different for half-cells of different efficiency levels; wherein, the PL grayscale average value threshold of the i-th level of the low-efficiency level is less than the PL grayscale average value threshold of the i-th level of the high-efficiency level; i is any integer between 1 and n. By optimizing the adaptation method between the high-efficiency level and the PL grayscale average value, the matching degree of the cells within the module is further improved, effectively suppressing EL brightness defects.

[0012] Preferably, for the same open-circuit voltage level, the difference in the average grayscale threshold of PL for half-cells with different efficiency levels at adjacent efficiency levels is not less than 5.

[0013] Optionally, the half-cell is a cell obtained by cutting the whole cell in half, one-third, or one-quarter.

[0014] Optionally, laser cutting can be used to cut the entire solar cell into half solar cells; Preferably, the entire battery cell is cut using laser cutting, and the half battery cell is passivated after cutting to obtain a half battery cell.

[0015] The second aspect of this application provides a half-cell photovoltaic module, which is prepared using the half-cell photovoltaic module preparation method provided in the first aspect of this application. Attached Figure Description

[0016] 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: Figure 1 A schematic flowchart of a method for fabricating a half-cell photovoltaic module according to this application is shown; Detailed Implementation

[0017] Embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0018] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise expressly specified. "Several" means one or more, unless otherwise expressly specified.

[0019] The first aspect of this application discloses a method for preparing a half-cell photovoltaic module, such as... Figure 1 As shown, the method includes: Select whole solar cells and test and classify the efficiency and / or open-circuit voltage of the whole solar cells; In this step, the substrate of the solar cell can be a monocrystalline silicon wafer, and the conductivity type of the monocrystalline silicon wafer can be P-type or N-type. The solar cell can be a TOPCon cell, PERC cell, BC cell, or HJT cell, etc. This application does not limit the substrate type or the type of solar cell.

[0020] A single solar cell refers to a solar cell made from a single silicon wafer cut from the same crystal rod. The dimensions of a single solar cell are generally rectangular, and can be 182mm×182mm, 182mm×183.75mm, 210mm×210mm, or 210mm×182mm, etc.

[0021] The efficiency and open-circuit voltage of a solar cell can be measured using a solar cell electrical performance tester. Cell efficiency characterizes the cell's ability to convert incident sunlight into electrical energy and is a core performance indicator of photovoltaic cells. The open-circuit voltage characterizes the maximum output voltage of the cell under no-load (open-circuit) conditions, essentially reflecting the built-in potential difference of the photovoltaic cell's PN junction, and is a key parameter of the cell's electrical characteristics.

[0022] After the entire solar cell is manufactured, its efficiency and open-circuit voltage are tested. The efficiency and / or open-circuit voltage of the entire solar cell are then graded to provide sorting data for the subsequent manufacturing method of photovoltaic modules.

[0023] Specifically, the efficiency ranges from 25.2% to 25.8%; the entire solar cell can be categorized into different efficiency ranges.

[0024] In one alternative approach, the efficiency difference between whole solar cells at the same efficiency level is no greater than 0.2%; for example, it could be 0%, 0.05%, 0.1%, 0.15%, or 0.2%; that is, the efficiency difference between any two whole solar cells at the same efficiency level is no greater than 0.2%.

[0025] For example, the efficiency range can be (25.3%, 25.4%), (25.4%, 25.5%), (25.5%, 25.6%), (25.6%, 25.7%), or (25.7%, 25.8%). This will be divided into 5 levels; the first efficiency level (25.3%, 25.4%) refers to a cell efficiency greater than 25.3% and less than or equal to 25.4%, the second efficiency level (25.4%, 25.5%) refers to... The first efficiency level is 25.4% to 25.5%; the second efficiency level (25.5%, 25.6%) refers to a cell efficiency of 25.5% to 25.6%; the third efficiency level (25.6%, 25.7%) refers to a cell efficiency of 25.6% to 25.7%; and the fourth efficiency level (25.7%, 25.8%) refers to a cell efficiency of 25.7% to 25.8%.

[0026] In one optional approach, the difference in efficiency thresholds between adjacent efficiency levels is not less than 0.1%; for example, it could be 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%. It should be noted that since an efficiency level is a range, this application defines the maximum value within each range as the efficiency threshold for that level; the difference in efficiency thresholds between adjacent efficiency levels refers to the difference in the maximum efficiency thresholds within the ranges of the two levels. Preferably, the difference in efficiency thresholds between adjacent efficiency levels is not less than 0.1% and not greater than 0.3%.

[0027] For example, for the efficiency level (25.3%, 25.4%), its efficiency threshold is 25.4%; the adjacent level of the efficiency level (25.3%, 25.4%) is (25.4%, 25.5%), and the efficiency threshold of (25.4%, 25.5%) is 25.5%. Therefore, the difference between the thresholds of the adjacent levels is not less than 0.1%, that is, the difference between 25.4% and 25.5% in the efficiency levels (25.3%, 25.4%) and (25.4%, 25.5%) is not less than 0.1%.

[0028] Specifically, the open-circuit voltage ranges from 726 to 746 mV; the entire solar cell can be categorized into different open-circuit voltage ranges.

[0029] In one alternative approach, the open-circuit voltage difference between any two cells within the same open-circuit voltage range is no greater than 6mV; for example, it could be 0mV, 1mV, 2mV, 3mV, 4mV, 5mV, or 6mV. In other words, the open-circuit voltage difference between any two cells within the same open-circuit voltage range is no greater than 6mV.

[0030] For example, the range of open-circuit voltage can be (726, 730], (730, 734], (734, 738], (738, 742], (742, 746). That is, it is divided into 5 levels; the first level (726, 730] means the open-circuit voltage of the solar cell must be greater than 726mV and less than or equal to 730mV; the second level (730, 734] means the open-circuit voltage of the solar cell must be greater than 730mV and less than or equal to 734mV; the third level (734, 738) means the open-circuit voltage of the solar cell must be greater than 734mV and less than or equal to 738mV; the fourth level (738, 742) means the open-circuit voltage of the solar cell must be greater than 738mV and less than or equal to 742mV; and the fifth level (742, 746)... This means that the open-circuit voltage of the solar cell must be greater than 742mV and less than or equal to 746mV.

[0031] In one alternative approach, the difference in open-circuit voltage thresholds between adjacent open-circuit voltage levels is not less than 4mV; for example, it could be 4mV, 5mV, 6mV, 7mV, or 8mV. It should be noted that, since an open-circuit voltage level is a range, this application defines the maximum value within each range as the open-circuit voltage threshold for that level; the difference in open-circuit voltage thresholds between adjacent open-circuit voltage levels refers to the difference in the maximum open-circuit voltage thresholds within the ranges of the two levels.

[0032] For example, for the open-circuit voltage range (726, 730], its open-circuit voltage threshold is 730mV; the adjacent range of the open-circuit voltage range (726, 730] is (730, 734], and the open-circuit voltage threshold of the open-circuit voltage range (730, 734] is 734mV. Then the difference between the thresholds of the adjacent ranges is not less than 4mV, that is, the difference between the open-circuit voltage thresholds of 730mV and 734mV in the open-circuit voltage ranges (726, 730] and (730, 734] is not less than 4mV.

[0033] The whole battery cell is cut into half battery cells; In this step, the entire battery cell is cut into half-cells. For example, the entire battery cell can be cut into half-cells by laser cutting, or into one-third-cells, or into one-quarter-cells.

[0034] In one specific embodiment, the half-cell is a cell obtained by cutting the whole cell in half, one-third, or one-quarter.

[0035] For example, 182mm×182mm can be cut into two half-cells of 182mm×91mm, or into three half-cells of 182mm×60.5mm, or into four half-cells of 182mm×45.5mm.

[0036] For example, 182mm×210mm can be cut into two half-cells of 182mm×105mm, or into three half-cells of 182mm×70mm, or into four half-cells of 182mm×52.5mm.

[0037] For example, a 210mm×210mm cell can be cut into two half-cells of 210mm×105mm, or into three half-cells of 210mm×70mm, or into four half-cells of 210mm×52.5mm.

[0038] In another specific embodiment, the entire battery cell is cut using laser cutting, and the half-cell is then passivated after cutting to obtain a half-cell battery cell. For example, an aluminum oxide or aluminum nitride passivation layer can be deposited on the cut surface using ALD (atomic layer deposition) or PEALD (plasma-enhanced atomic layer deposition).

[0039] The half-cell battery cell is subjected to PL testing, and the cells are classified according to the average grayscale value of the PL image. In this step, each half of the cut battery cell undergoes a photoplethysmography (PL) test. The PL test is performed using a PL measuring instrument, such as a Semilab PL measuring instrument, to measure the PL of the battery cell and obtain a PL image. The PL image is a black and white image, quantized using grayscale values. Grayscale values ​​are a well-known numerical value in computer image processing used to represent the brightness or color depth of an image, typically ranging from 0 to 255, where 0 represents black and 255 represents white. In this application, the grayscale values ​​of the entire PL image are represented using these grayscale values, ranging from 0 to 255, with 255 for white and 0 for black. The grayscale mean is the average of all grayscale values ​​across the entire half of the battery cell. Depending on the pixel count of the PL camera, different numbers of grayscale values ​​will be generated on the PL image; the grayscale mean of the half of the battery cell is the average of all grayscale values.

[0040] Specifically, when a whole solar cell is cut into half cells, the cutting process damages the cells, which can affect the performance of the half cells. At this point, it is necessary to add testing equipment for the half cells when conducting efficiency and open-circuit voltage tests. Furthermore, since efficiency and open-circuit voltage tests are both contact tests, there is a possibility of introducing impurities into the half cells.

[0041] Laser-based particle (PL) testing does not require contact with half-cells and is not limited by silicon wafer size, making it simple and convenient. However, when measuring a whole cell before cutting, the laser cutting process damages the cell, resulting in differences in the PL images before and after cutting. Furthermore, the cell images themselves may exhibit uneven PL image quality. For example, on a whole cell, the grayscale value of the PL image in the upper left corner may be darker than that in the upper right corner. If the cell is cut into two half-cells in a left-right order, the difference in grayscale values ​​between the two half-cells will be significant. Using the grayscale values ​​from the original whole cell's PL image will lead to discrepancies, affecting the subsequent sorting of the half-cells.

[0042] Specifically, the average gray value of PL ranges from 90 to 155, which allows half-cell batteries to be categorized into different ranges of average gray values ​​of PL.

[0043] In one optional approach, the difference in the average grayscale value of the half-cells within the same PL grayscale average value range is no greater than 30; for example, it can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 15, 20, 25, or 30; that is, the difference in the average grayscale value of any two half-cells within the same PL grayscale average value range is no greater than 30. Preferably, the difference in the average grayscale value of the half-cells within the same PL grayscale average value range is no greater than 10.

[0044] For example, the range of the grayscale mean level of PL can be (90, 95], (95, 100], (100, 105], (105, 110], (110, 115). That is, the grayscale mean of PL is divided into 5 grayscale values ​​as an interval. The first grayscale mean level (90, 95] means that the grayscale mean is greater than 90 and less than or equal to 95; the second grayscale mean level (95, 100] means that the grayscale mean is greater than 95 and less than or equal to 100; the third grayscale mean level (100, 105] means that the grayscale mean is greater than 100 and less than or equal to 105; the fourth grayscale mean level (105, 110) means that the grayscale mean is greater than 105 and less than or equal to 110; and the fifth grayscale mean level (110, 115) means that the grayscale mean is greater than 110 and less than or equal to 115.

[0045] In one optional approach, the difference in grayscale mean threshold between adjacent grayscale mean levels is not less than 5; for example, it can be 5, 6, 7, 8, 9, or 10. It should be noted that since a grayscale mean level is a range, this application defines the maximum value within each range as the grayscale mean threshold for that level; the difference in grayscale mean threshold between adjacent grayscale mean levels refers to the difference in the maximum grayscale mean threshold between the two levels. Preferably, the difference in grayscale mean threshold between adjacent grayscale mean levels is not less than 5 and not greater than 10.

[0046] For example, for the grayscale average level (90, 95], its grayscale average threshold is 95; the adjacent level of the grayscale average level (90, 95] is (95, 100], and the grayscale average threshold of the grayscale average level (95, 100] is 100. Then the difference between the adjacent grayscale average thresholds is not less than 5, that is, the difference between the grayscale average threshold 95 of the grayscale average level (90, 95] and the grayscale average threshold 100 of the grayscale average level (95, 100] is not less than 5.

[0047] In one optional approach, based on the average grayscale value threshold of PL, the average grayscale value is divided into n levels, where n ≥ 2, for example, n can be 2, 3, 4, 5, or 6. For half-cells with the same efficiency level but different open-circuit voltage levels, the average grayscale value threshold of the same PL level is different. Specifically, the average grayscale value threshold of the PL at the i-th level of the low open-circuit voltage level is less than the average grayscale value threshold of the PL at the i-th level of the high open-circuit voltage level, where i is any integer between 1 and n. In particular, when the selection of half-cells is based on a combination of efficiency and open-circuit voltage, for half-cells with different open-circuit voltage levels within the same efficiency level, the average grayscale value threshold of the same PL level is different. For example, when a half-cell is at the (25.2%, 25.3%) efficiency level, for half-cells at the open-circuit voltage levels (730, 734) and (734, 738), the average grayscale threshold of the PL at the first level of the former is less than the average grayscale threshold of the PL at the first level of the latter; the average grayscale threshold of the PL at the second level of the former is less than the average grayscale threshold of the PL at the second level of the latter; the average grayscale threshold of the PL at the third level of the former is less than the average grayscale threshold of the PL at the third level of the latter.

[0048] In a specific embodiment, when a half-cell is at the efficiency level of (25.2%, 25.3%), for a half-cell with an open-circuit voltage level of (730, 734), its average PL grayscale level can be divided into three levels: (90, 95], (95, 100], and (100, 105]; for a half-cell with an open-circuit voltage level of (734, 738), its average PL grayscale level can be divided into three levels: (95, 100], (100, 105], and (105, 110).

[0049] In one specific embodiment, for the same efficiency level, the difference in the average grayscale threshold of PL for the i-th level of adjacent open-circuit voltage levels of the half-cells is not less than 5.

[0050] For example, when a half-cell is at the (25.2%, 25.3%) efficiency level, for half-cells at the open-circuit voltage levels (730, 734) and (734, 738), the average grayscale threshold of the first PL level of the former is less than the average grayscale threshold of the first PL level of the latter; for example, the first PL level of the former can be (90, 95) with an average grayscale threshold of 95, and the first PL level of the latter can be (95, 100) with an average grayscale threshold of 100; the difference between the two average grayscale thresholds is not less than 5.

[0051] In one optional approach, the average gray value of PL is divided into n levels based on the average gray value threshold, where n ≥ 2, for example, n can be 2, 3, 4, 5, or 6. For the same open-circuit voltage level, the average gray value threshold of the same PL gray value level is different for half-cells of different efficiency levels. Specifically, the average gray value of PL in the i-th level of the low-efficiency level is less than the average gray value threshold of PL in the i-th level of the high-efficiency level. Here, i is any integer between 1 and n.

[0052] Specifically, when the screening of half-cells is based on open-circuit voltage combined with efficiency, for half-cells with different efficiency levels at the same open-circuit voltage level, the gray-scale average threshold for the same PL gray-scale average level is different. For example, when the open-circuit voltage of half-cells is in the (730, 734) range, for half-cells in the efficiency ranges (25.2%, 25.3%] and (25.3%, 25.4%), the average gray value threshold of the PL in the first range of the former is less than the average gray value threshold of the PL in the first range of the latter; the average gray value threshold of the PL in the second range of the former is less than the average gray value threshold of the PL in the second range of the latter; the average gray value threshold of the PL in the third range of the former is less than the average gray value threshold of the PL in the third range of the latter.

[0053] In a specific embodiment, when a half-cell is at the open-circuit voltage level of (730, 734), for a half-cell with an efficiency level of (25.2%, 25.3%), its average PL grayscale level can be divided into three levels: (90, 95], (95, 100], and (100, 105]; for a half-cell with an efficiency level of (25.3%, 25.4%), its average PL grayscale level can be divided into three levels: (95, 100], (100, 105], and (105, 110).

[0054] In one specific embodiment, for the same open-circuit voltage level, the difference in the average grayscale threshold of PL for half-cells with different efficiency levels at adjacent efficiency levels is not less than 5.

[0055] For example, when the open-circuit voltage of half-cells is in the range (730, 734), for half-cells in the efficiency ranges (25.2%, 25.3%] and (25.3%, 25.4%), the average grayscale threshold of the first PL range of the former is less than the average grayscale threshold of the first PL range of the latter; for example, the average grayscale threshold of the first PL range of the former can be (90, 95) with a grayscale threshold of 95, and the average grayscale threshold of the latter can be (95, 100) with a grayscale threshold of 100; the difference between the average grayscale thresholds of the two is not less than 5.

[0056] It should be noted that in this application, the efficiency and open-circuit voltage ratings of the half-cells are directly adopted from the test ratings of the corresponding full-cell cells before cutting. Although laser cutting may cause slight damage to the edges of the half-cells, resulting in differences in efficiency or open-circuit voltage, the differences between the two half-cells obtained from cutting the same full-cell cell are symmetrical, and the method in this application controls the efficiency and open-circuit voltage ratings within a certain range. Therefore, in mass production, directly using the full-cell ratings can still ensure consistent cell matching in the modules, and there is no need to add new equipment for testing the electrical performance of the half-cells, thus avoiding increased costs.

[0057] The half-cell solar cells with the same efficiency level and / or the same open-circuit voltage level and the same PL grayscale average level are arranged in the same half-cell photovoltaic module to complete the fabrication of the half-cell photovoltaic module.

[0058] In this step, when screening is performed using a standard combining efficiency and average PL grayscale value, half-cell solar cells with the same efficiency level and the same average PL grayscale value are placed in the same half-cell photovoltaic module to complete the fabrication of the half-cell photovoltaic module; when screening is performed using a standard combining open-circuit voltage and average PL grayscale value, half-cell solar cells with the same open-circuit voltage level and the same average PL grayscale value are placed in the same half-cell photovoltaic module to complete the fabrication of the half-cell photovoltaic module; when screening is performed using a standard combining efficiency, open-circuit voltage, and average PL grayscale value, half-cell solar cells with the same efficiency level, the same open-circuit voltage level, and the same average PL grayscale value are placed in the same half-cell photovoltaic module to complete the fabrication of the half-cell photovoltaic module.

[0059] In one alternative approach, when the efficiency level of the half-cell in the same half-cell photovoltaic module is (25.2%, 25.3%): If the open-circuit voltage level of the half cell in the same half-cell photovoltaic module is (730, 734] mV, then the average grayscale value level of the half cell in the same half-cell photovoltaic module is at least one of (90, 100], (95, 105] or (100, 110]. If the open-circuit voltage level of the half cell in the same half-cell photovoltaic module is (734, 738] mV, then the average gray value level of the PL of the half cell in the same half-cell photovoltaic module is at least one of (100, 110], (105, 115] or (110, 120]. If the open-circuit voltage level of the half cell in the same half-cell photovoltaic module is (738, 742] mV, then the average grayscale value level of the half cell in the same half-cell photovoltaic module is at least one of (110, 120], (115, 125] or (120, 130].

[0060] In one alternative approach, when the efficiency level of the half-cell in the same half-cell photovoltaic module is (25.3%, 25.4%): If the open-circuit voltage level of the half cell in the same half-cell photovoltaic module is (730, 734] mV, then the average grayscale value level of the half cell in the same half-cell photovoltaic module is at least one of (95, 105], (100, 110] or (105, 115]. If the open-circuit voltage level of the half cell in the same half-cell photovoltaic module is (734, 738] mV, then the average grayscale value level of the half cell in the same half-cell photovoltaic module is at least one of (105, 115], (110, 120] or (115, 125]. If the open-circuit voltage level of the half cell in the same half-cell photovoltaic module is (738, 742] mV, then the average grayscale value level of the half cell in the same half-cell photovoltaic module is at least one of (115, 125], (120, 130] or (125, 135].

[0061] In one alternative approach, when the efficiency level of the half-cell in the same half-cell photovoltaic module is (25.4%, 25.5%): If the open-circuit voltage level of the half cell in the same half-cell photovoltaic module is (730, 734] mV, then the average gray value level of the PL of the half cell in the same half-cell photovoltaic module is at least one of (100, 110], (105, 115] or (125, 135]. If the open-circuit voltage level of the half cell in the same half-cell photovoltaic module is (734, 738] mV, then the average gray value level of the PL of the half cell in the same half-cell photovoltaic module is at least one of (110, 120], (115, 125] or (135, 145]. If the open-circuit voltage level of the half cell in the same half-cell photovoltaic module is (738, 742] mV, then the average grayscale value level of the half cell in the same half-cell photovoltaic module is at least one of (120, 130], (125, 135] or (145, 155].

[0062] The second aspect of this application discloses a half-cell photovoltaic module, which is prepared using the half-cell photovoltaic module preparation method of the first aspect of this application, and the prepared photovoltaic module has low EL brightness and darkness defects.

[0063] The following describes in detail, with several specific embodiments, the method for preparing a half-cell photovoltaic module disclosed in the first aspect of this application and the half-cell photovoltaic module disclosed in the second aspect. It is to be understood that the following description is merely illustrative and not intended to limit the invention.

[0064] All the complete solar cells in the following examples and comparative examples are made from N-type monocrystalline silicon wafers of the same specifications provided by the same supplier as substrates, and are prepared using the same cell process to obtain the same batch of Topcon complete solar cells. The size of the complete solar cell is 182mm×182mm. Example

[0065] A solar cell efficiency tester was used to test and sort the efficiency and / or open-circuit voltage of the entire solar cell. A PL tester was used to test the average grayscale value of the entire solar cell (used for the preparation of control group 4). The first type of whole solar cell is sorted by efficiency and open-circuit voltage level. The efficiency level is selected as (25.2%, 25.3%), and the open-circuit voltage has three levels (730, 734), (734, 738), and (738, 742). The second type of whole cell is sorted by efficiency, open circuit voltage level and grayscale mean of whole cell PL image. The efficiency level is selected as (25.2%, 25.3%), the open circuit voltage level is selected as (730, 734) and the PL grayscale mean level is selected as (90, 120). The third type of whole solar cell was sorted by efficiency level, with the selected efficiency levels being (25.2%, 25.3%). The fourth type of whole solar cell was sorted only by open-circuit voltage level, and the selected level was (734, 738). The efficiency and open-circuit voltage of the whole solar cells of the fifth, sixth and seventh types were tested. The efficiency range of the fifth type was (25.2%, 25.3%) and the open-circuit voltage range was (730, 734); the efficiency range of the sixth type was (25.2%, 25.3%) and the open-circuit voltage range was (734, 738); and the efficiency range of the seventh type was (25.2%, 25.3%) and the open-circuit voltage range was (738, 742).

[0066] The seven types of whole solar cells mentioned above were laser-cut into 182mm × 91mm half-cells, and the laser-cut surfaces (i.e., the laser-cut sides) were passivated with alumina using ALD. Based on the above half-cells, control and experimental groups were prepared as shown in Table 1 below.

[0067] (1) Preparation of control group 1, control group 2 and control group 3: The PL image of half cell was not tested. Half cells of the same efficiency level and the same open circuit voltage level in the first type were used to prepare half photovoltaic modules. Three groups of control group half photovoltaic modules were obtained. Each control group contained 70 half photovoltaic modules. The EL image of the photovoltaic module and the EL defect rate were measured by the OPT-M960B model EL measuring instrument of Optech.

[0068] (2) Preparation of control group 4: Without testing the PL image of half cell, half cells of the second type with the same efficiency level, the same open circuit voltage level and the average PL gray value level of the whole cell (90, 120) were used to prepare half cells of photovoltaic modules to obtain a group of control group half cells of photovoltaic modules. Each control group contained 70 half cells of photovoltaic modules. The EL image and EL defect rate of the photovoltaic modules were measured using the OPT-M960B model EL measuring instrument of Optech.

[0069] (3) Preparation of test groups 1-2: The gray average value of half-cells obtained by cutting whole cells of the third and fourth types was tested using a PL tester. The gray average value range was set to (90, 120). Half-cells of the third type with the same efficiency range and the same PL gray average value range were set in the same half-cell photovoltaic module to prepare test group 1. Half-cells of the fourth type with the same open circuit voltage range and the same PL gray average value range were set in the same half-cell photovoltaic module to prepare test group 2. Each test group contained 70 half-cell photovoltaic modules. The EL image and EL defect ratio of the photovoltaic modules were measured using an OPT-M960B model EL measuring instrument of Optech.

[0070] (4) Preparation of test groups 3, 4 and 5. The grayscale mean of half-cells obtained by cutting whole-cell cells of the fifth, sixth and seventh types was tested using a PL tester. The grayscale mean range was set to (90, 120]. Half-cell cells with the same efficiency range, the same open-circuit voltage range and the same PL grayscale mean range were set in the same half-cell photovoltaic module to obtain three test groups of half-cell photovoltaic modules. Each test group contained 70 half-cell photovoltaic modules. The EL image and EL defect rate of the photovoltaic modules were measured using an OPT-M960B model EL measuring instrument of Optech.

[0071] (5) Preparation of test groups 6 and 7. The grayscale average of half-cells obtained by cutting whole-cell cells of type 6 and type 7 was tested using a PL tester; the grayscale average range of the open-circuit voltage range (734, 738) was set to (95, 125], and the grayscale average range of the open-circuit voltage range (738, 742) was set to (100, 130]. ​​Half-cell cells of the same efficiency range, the same open-circuit voltage range, and the same PL grayscale average range were then set in the preparation of the same half-cell photovoltaic module to obtain two groups of half-cell photovoltaic modules. Each test group contained 70 half-cell photovoltaic modules. The EL image and EL defect rate of the photovoltaic modules were measured using an OPT-M960B EL measuring instrument from Optech.

[0072] (6) Preparation of test groups 8-16: The grayscale average of half-cells obtained by cutting whole-cell cells of types 5, 6 and 7 was tested using a PL tester; three PL grayscale average ranges were set for each open-circuit voltage range. The grayscale average ranges for the (730, 734] open-circuit voltage range were set to (90, 100], (100, 110] and (110, 120]; the grayscale average ranges for the (734, 738] open-circuit voltage range were set to (95, 105], (105, 115] and (115, 125]. The grayscale average range of the open-circuit voltage range (738, 742) was set to (100, 110), (110, 120), and (120, 130). Half-cells with the same efficiency range, the same open-circuit voltage range, and the same PL grayscale average range were then used in the preparation of the same half-cell photovoltaic module. Nine experimental groups of half-cell photovoltaic modules were obtained, with each experimental group containing 70 half-cell photovoltaic modules. The EL image and EL defect rate of the photovoltaic modules were measured using an OPT-M960B EL measuring instrument from Optech.

[0073] Table 1 below shows the parameters and EL brightness defect ratio of control group 1-4 and experimental group 1-16. As can be seen from the table, (1) compared with control group 1-4, the EL brightness defect ratio of experimental group 1-16 is significantly reduced; (2) compared with control group 4 which uses the average gray value of the whole cell as the sorting standard, and experimental group 3 which uses the PL sorting standard of half cell, the EL brightness defect of experimental group 3 is significantly reduced; (3) compared with experimental group 1 and experimental group 2 which only use the sorting standard of efficiency or open circuit voltage combined with the average gray value of half cell, the EL brightness defect of experimental group 3 is significantly reduced by the sorting standard of efficiency, open circuit voltage combined with the average gray value of half cell. (4) Compared with test group 4, the open circuit voltage level of test group 6 is higher and the average gray value level of PL is higher, which is more conducive to improving PL defects and EL brightness defects. Similarly, compared with test group 5, the open circuit voltage level of test group 7 is higher and the average gray value level of PL is higher, which is more conducive to improving PL defects and EL brightness defects. (5) Compared with test groups 1-7, test groups 8-10, 11-13 and 14-16 significantly reduced the proportion of EL brightness defects by controlling the average gray value of PL through gradient control, and the proportion of unqualified PL upper limit NG and PL lower limit NG were low.

[0074] Table 1. Parameters and EL brightness / darkness ratio of control groups 1-4 and experimental groups 1-16 Example

[0075] The efficiency and open-circuit voltage of the entire solar cells in the aforementioned batch were tested using a solar cell efficiency tester. Three efficiency levels were selected: (25.2%, 25.3%), (25.3%, 25.4%), and (25.4%, 25.5%). Within each efficiency level, three open-circuit voltage levels were selected: (730, 734%), (734, 738%), and (738, 742%). The nine efficiency levels of the entire solar cells were then laser-cut into 182mm × 91mm half-cells. The laser-cut surface was passivated. Based on the above half-cell solar cells, the half-cell solar cells were divided into PL grayscale average values, with each value set as a PL grayscale average value level. Half-cell photovoltaic modules with the same efficiency level, open-circuit voltage level, and PL grayscale average value level were prepared in the same half-cell photovoltaic module. This resulted in 27 experimental groups of half-cell photovoltaic modules, each containing 70 half-cell photovoltaic modules. The EL images and EL defect rate of the photovoltaic modules were measured using an OPT-M960B EL measuring instrument from Optech.

[0076] Table 2 below shows the parameters, PL upper and lower limit NG ratio, and EL brightness defect ratio for test group 17-43. As can be seen from the table, by preparing half-cell photovoltaic modules with half-cells of different efficiency levels, different open circuit voltage levels, and different PL grayscale average levels, the proportion of EL sensitive defects can be effectively reduced, and the PL upper limit NG ratio and PL lower limit NG ratio are low.

[0077] Table 2. Parameters and EL brightness / darkness ratio of test group 17-43

[0078] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple instances. 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.

[0079] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of this application as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from the spirit and scope of this application. Thus, if such modifications and modifications of this application fall within the scope of the claims of this application and their equivalents, this application is also intended to include such modifications and modifications.

Claims

1. A method for preparing a half-cell photovoltaic module, characterized in that, The method includes: Select whole solar cells and test and classify the efficiency and / or open-circuit voltage of the whole solar cells; The whole battery cell is cut into half battery cells; The half-cell battery cell is subjected to PL testing, and the cells are classified according to the average grayscale value of the PL image. The half-cell solar cells with the same efficiency level and / or the same open-circuit voltage level and the same PL grayscale average level are arranged in the same half-cell photovoltaic module to complete the fabrication of the half-cell photovoltaic module.

2. The preparation method according to claim 1, characterized in that, The efficiency difference of the whole cell at the same efficiency level is no greater than 0.2%; and / or, the open-circuit voltage difference of the whole cell at the same open-circuit voltage level is no greater than 6mV; and / or, the difference in grayscale mean of the half cell at the same PL grayscale mean level is no greater than 30; preferably, the difference in grayscale mean of the half cell at the same PL grayscale mean level is no greater than 10.

3. The preparation method according to claim 2, characterized in that, The difference in efficiency threshold between adjacent efficiency levels shall not be less than 0.1%; and / or the difference in open-circuit voltage threshold between adjacent open-circuit voltage levels shall not be less than 4mV; and / or the difference in grayscale mean threshold between adjacent PL grayscale mean levels shall not be less than 5.

4. The preparation method according to claim 3, characterized in that, Based on the PL gray-scale mean threshold, the PL gray-scale mean is divided into n levels, where n≥2. For the same efficiency level, the gray-scale mean threshold of the same PL gray-scale mean level is different for the half-cells with different open-circuit voltage levels. Among them, the PL gray-scale mean threshold of the i-th level of the low open-circuit voltage level is less than the PL gray-scale mean threshold of the i-th level of the high open-circuit voltage level; i is any integer between 1 and n.

5. The preparation method according to claim 4, characterized in that, For the same efficiency level, the difference in the average grayscale threshold of PL for the i-th level of adjacent open-circuit voltage levels of the half-cells is not less than 5.

6. The preparation method according to claim 3, characterized in that, Based on the PL gray-scale average threshold, the PL gray-scale average is divided into n levels, where n≥2. For the same open-circuit voltage level, the gray-scale average threshold of the same PL gray-scale average level is different for the half-cells of different efficiency levels. Among them, the PL gray-scale average threshold of the i-th level of the low-efficiency level is less than the PL gray-scale average threshold of the i-th level of the high-efficiency level. i is any integer between 1 and n.

7. The preparation method according to claim 6, characterized in that, For the same open-circuit voltage level, the difference in the average grayscale threshold of PL for half-cells with different efficiency levels is not less than 5 for the i-th level of adjacent efficiency levels.

8. The preparation method according to claim 1, characterized in that, The half-cell is a cell obtained by cutting the whole cell in half, one-third, or one-quarter.

9. The preparation method according to claim 1, characterized in that, Laser cutting is used to cut a whole solar cell into half solar cells; Preferably, the entire battery cell is cut using laser cutting, and the half battery cell is passivated after cutting to obtain a half battery cell.

10. A half-cell photovoltaic module, characterized in that, It is prepared using the method for preparing a half-cell photovoltaic module according to any one of claims 1-9.

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