Back contact solar cell reliability test structure and back contact solar cell reliability test method

Abstract

The invention provides a back contact solar cell reliability test structure and a back contact solar cell reliability test method. The back contact solar cell reliability test structure comprises a back contact solar cell, a light transmitting layer, a conductive layer and a backboard layer. A first electrode and a second electrode which are opposite in polarity are arranged on the back face of the back contact solar cell, the light transmitting layer is arranged on the front face of the back contact solar cell, the back plate layer is arranged on the back face of the back contact solar cell, the conducting layer is arranged between the back contact solar cell and the back plate layer, and the first electrode and the second electrode are both in contact with the conducting layer. The back contact solar cell reliability test structure is beneficial for rapidly and accurately testing the reliability of the back contact solar cell packaged into a back contact photovoltaic module in an ultraviolet irradiation environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of back contact solar cell performance testing, in particular to a back contact solar cell reliability test structure and a back contact solar cell reliability test method. BACKGROUND

[0002] A photovoltaic module is obtained by encapsulating a plurality of solar cells. During outdoor use, the photovoltaic module will inevitably be exposed to ultraviolet radiation, and therefore UV testing is an important means of verifying the reliability of the photovoltaic module in an outdoor ultraviolet radiation environment. However, the structure of a back contact photovoltaic module is different from that of a conventional photovoltaic module, and how to effectively simulate the reliability of a back contact photovoltaic module in an outdoor ultraviolet radiation environment is a problem that needs to be solved in the industry. SUMMARY

[0003] Therefore, the present application provides a back contact solar cell reliability test structure and a back contact solar cell reliability test method, which are beneficial to quickly and accurately testing the reliability of a back contact solar cell after being encapsulated into a back contact photovoltaic module in an ultraviolet radiation environment.

[0004] The technical solutions of the present application are as follows:

[0005] According to a first aspect of the present application, a back contact solar cell reliability test structure is provided, comprising a back contact solar cell, a light-transmitting layer, a conductive layer, and a back plate layer. The back surface of the back contact solar cell has a first electrode and a second electrode with opposite polarities. The light-transmitting layer is arranged on the front surface of the back contact solar cell. The back plate layer is arranged on the back surface of the back contact solar cell. The conductive layer is arranged between the back contact solar cell and the back plate layer. The first electrode and the second electrode are both in contact with the conductive layer.

[0006] The above-mentioned back contact solar cell reliability test structure sets a light-transmitting layer on the front surface of the back contact solar cell and a back plate layer on the back surface of the back contact solar cell, and encapsulates the front surface and the back surface of the back contact solar cell through the light-transmitting layer and the back plate layer. A conductive layer is arranged between the back contact solar cell and the back plate layer, and the first electrode and the second electrode are both in contact with the conductive layer, so that the first electrode and the second electrode of the back contact solar cell are short-circuited. The back contact solar cell reliability test structure can better simulate the structure of a back contact photovoltaic module after a back contact solar cell is encapsulated into the back contact photovoltaic module and tested in a short-circuit mode, and is beneficial to quickly and accurately testing the reliability of the back contact photovoltaic module in an ultraviolet radiation environment.

[0007] In some embodiments, the material of the conductive layer includes one or more of copper, silver, gold, aluminum, and tin.

[0008] In some embodiments, the electric conductivity of the conductive layer is greater than or equal to 10 4 S / m.

[0009] In some embodiments, the thickness of the conductive layer is 5 μm to 100 μm.

[0010] In some embodiments, the orthographic projection of the back contact solar cell on the back sheet layer does not exceed the range of the orthographic projection of the conductive layer on the back sheet layer along the thickness direction of the back contact solar cell reliability test structure.

[0011] In some embodiments, the average transmittance of the light-transmitting layer to light with a wavelength of 300 nm to 1200 nm is 88% to 98%, and the average transmittance to light with a wavelength of 300 nm to 400 nm is 5% to 80%.

[0012] In some embodiments, the thickness of the light-transmitting layer is 0.5 mm to 5 mm.

[0013] In some embodiments, the thickness of the back sheet layer is greater than or equal to 1 mm.

[0014] In some embodiments, the back contact solar cell reliability test structure further comprises an adhesive layer, which is arranged between the conductive layer and the back sheet layer.

[0015] According to a second aspect of the present application, a back contact solar cell reliability test method is provided, comprising the following steps:

[0016] Testing the photoelectric conversion efficiency of the back contact solar cell to obtain an initial photoelectric conversion efficiency;

[0017] Assembling the back contact solar cell into the above-mentioned back contact solar cell reliability test structure;

[0018] Performing ultraviolet aging treatment on the back contact solar cell reliability test structure using ultraviolet light;

[0019] Testing the photoelectric conversion efficiency of the back contact solar cell in the back contact solar cell reliability test structure after the ultraviolet aging treatment to obtain an ultraviolet aging photoelectric conversion efficiency;

[0020] Dividing the difference between the initial photoelectric conversion efficiency and the ultraviolet aging photoelectric conversion efficiency by the initial photoelectric conversion efficiency to obtain the UV decay rate of the back contact solar cell. BRIEF DESCRIPTION OF DRAWINGS

[0021] For a better understanding of the embodiments or examples provided by the present application, one or more of the accompanying drawings are referred to. Additional details or examples used to describe the drawings should not be considered as limiting the scope of the disclosed application, the presently described embodiments or examples, and the best mode of these applications presently understood. Moreover, in all the drawings, the same reference numbers are used to represent the same components. In the drawings:

[0022] Figure 1 A schematic diagram of a back contact solar cell reliability test structure according to an embodiment of the present application.

[0023] Figure 2 A schematic diagram of a back contact solar cell reliability test structure according to another embodiment of the present application.

[0024] Figure 3 A schematic diagram of a back contact solar cell and its contact with a conductive layer in a back contact solar cell reliability test structure according to an embodiment of the present application.

[0025] Figure 4 A flow chart of a back contact solar cell reliability test method according to an embodiment of the present application.

[0026] Legend of reference signs:

[0027] 10, back contact solar cell reliability test structure; 11, back contact solar cell; 12, light-transmitting layer; 13, conductive layer; 14, back sheet layer; 15, adhesive layer; 111, first electrode; 112, second electrode; 113, silicon substrate; 114, first doped silicon layer; 115, second doped silicon layer; 116, tunneling oxide layer; 117, passivation layer; 118, anti-reflection layer. DETAILED DESCRIPTION

[0028] In order to make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application are described in detail below. In the following description, a lot of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0029] In addition, the terms "first", "second" are only used for descriptive purposes, and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise specifically limited.

[0030] In this application, unless otherwise clearly indicated and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be direct connection, can also be indirect connection through an intermediate medium, can be internal communication of two elements or interaction relationship between two elements, unless otherwise clearly limited. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0032] The inventor has found through research that when the UV test is performed on the back contact photovoltaic module end, short circuit mode, open circuit mode or maximum power point tracking (MPPT) mode can be selected, and the short circuit mode is usually used for testing. However, since the back contact photovoltaic module is large in size, the test equipment is required to have a large floor area and a long operation and maintenance time, thereby resulting in a long UV test cycle of the back contact photovoltaic module and a shortage of resources. The traditional UV test method for a single back contact solar cell belongs to open voltage mode testing, and the UV decay rate of the back contact solar cell measured thereby is greatly different from the test result of the module end, and cannot accurately reflect the reliability of the back contact solar cell in an ultraviolet irradiation environment after being packaged into a back contact photovoltaic module.

[0033] Please refer to Figure 1 、 Figure 2 and Figure 3 , an embodiment of the present application provides a back contact solar cell reliability test structure 10, which comprises a back contact solar cell 11, a light-transmitting layer 12, a conductive layer 13 and a back plate layer 14; the back surface of the back contact solar cell 11 has a first electrode 111 and a second electrode 112 with opposite polarities, the light-transmitting layer 12 is arranged on the front surface of the back contact solar cell 11, the back plate layer 14 is arranged on the back surface of the back contact solar cell 11, the conductive layer 13 is arranged between the back contact solar cell 11 and the back plate layer 14, and the first electrode 111 and the second electrode 112 are both in contact with the conductive layer 13.

[0034] Traditional UV testing of back-contact photovoltaic (PV) modules suffers from long testing cycles and resource constraints due to the large module size, requiring extensive testing equipment and extended operation and maintenance time. This hinders rapid reliability testing of back-contact PV modules under ultraviolet (UV) irradiation. Furthermore, traditional UV testing of individual back-contact solar cells is conducted in open-voltage mode, resulting in a significant discrepancy between the UV degradation rate obtained from individual cells and the module-level test results. This makes it difficult to accurately reflect the reliability of back-contact solar cells encapsulated in back-contact PV modules under UV irradiation.

[0035] The back-contact solar cell reliability testing structure 10 described in this application includes a light-transmitting layer 12 on the front side of the back-contact solar cell 11 and a backsheet layer 14 on the back side of the back-contact solar cell 11, which encapsulates the front and back sides of the back-contact solar cell 11. A conductive layer 13 is disposed between the back-contact solar cell 11 and the backsheet layer 14, and both the first electrode 111 and the second electrode 112 are in contact with the conductive layer 13, thus forming a short circuit between the first electrode 111 and the second electrode 112 of the back-contact solar cell 11. This back-contact solar cell reliability testing structure 10 can effectively simulate the structure of the back-contact solar cell 11 after being encapsulated into a back-contact photovoltaic module and subjected to UV testing in a short-circuit mode. The volume of the testing structure is significantly reduced compared to the volume of the back-contact photovoltaic module, eliminating the need for large-footprint and long-operation-maintenance testing equipment. This facilitates rapid and accurate testing of the reliability of the back-contact solar cell after it has been encapsulated into a back-contact photovoltaic module under ultraviolet radiation.

[0036] Understandably, the opposite polarities of the first electrode 111 and the second electrode 112 mean that one of the first electrode 111 and the second electrode 112 is a positive electrode and the other is a negative electrode. For example, when the first electrode 111 is a positive electrode, the second electrode 112 is a negative electrode, and when the first electrode 111 is a negative electrode, the second electrode 112 is a positive electrode.

[0037] In some embodiments, the conductive layer 13 is made of one or more of copper, silver, gold, aluminum, and tin. Using these materials as the conductive layer 13 provides high conductivity, effectively connecting the first electrode 111 and the second electrode 112 to form a short circuit. This facilitates a better simulation of the structure of a back-contact photovoltaic module during UV testing in a short-circuit mode.

[0038] It should be noted that the material of the conductive layer 13 is not limited to the specific material types mentioned above, and can also be other conductive materials that meet the conductivity requirements.

[0039] In some specific examples, the conductive layer 13 can be a foil formed of the aforementioned metallic materials, such as copper foil, silver foil, gold foil, aluminum foil, and tin foil.

[0040] In some embodiments, the conductivity of the conductive layer 13 is greater than or equal to 10. 4 S / m. By controlling the conductivity of the conductive layer 13 within the aforementioned range, the first electrode 111 and the second electrode 112 can be effectively electrically connected to form a short circuit, thus better simulating the structure of a back-contact photovoltaic module during UV testing in a short-circuit mode. Understandably, the conductivity of the conductive layer 13 can be, but is not limited to, 1×10⁻⁶. 4 S / m, 5×10 4 S / m, 1×10 5 S / m, 5×10 5 S / m, 1×10 6 S / m, 5×10 6 S / m, 1×10 7 S / m, 5×10 7 Specific values ​​such as S / m.

[0041] In this application, the conductivity of the conductive layer 13 can be tested using conventional methods for testing the conductivity of metal foils, such as the four-probe method.

[0042] In some embodiments, the thickness of the conductive layer 13 is 5 μm to 100 μm. Controlling the thickness of the conductive layer 13 within the above range can effectively connect the first electrode 111 and the second electrode 112 to form a short circuit, which is beneficial for better simulating the structure of a back-contact photovoltaic module when performing UV testing in a short-circuit mode.

[0043] In this application, the thickness of the conductive layer 13 can be 5μm, 8μm, 10μm, 12μm, 15μm, 18μm, 20μm, 22μm, 25μm, 28μm, 30μm, 32μm, 35μm, 38μm, 40μm, 42μm, 45μm, 48μm, 50μm, 52μm, 55μm, 58μm, 60μm, 62μm, 65μm, 68μm, 70μm, 72μm, 75μm, 78μm, 80μm, 82μm, 85μm, 88μm, 90μm, 92μm, 95μm, 98μm, 100μm, or any value within the range formed by any two of the above values.

[0044] In some embodiments, along the thickness direction of the back contact solar cell reliability test structure 10 (see...) Figure 1(As shown in the direction of M), the orthographic projection of the back contact solar cell 11 onto the backsheet layer 14 does not exceed the orthographic projection range of the conductive layer 13 onto the backsheet layer 14. That is, the size of the conductive layer 13 is at least able to completely cover the back side of the back contact solar cell 11, either exactly completely covering the back side of the back contact solar cell 11, or the edge of the conductive layer 13 extends beyond the edge of the back contact solar cell 11.

[0045] This allows all the first electrodes 111 and the second electrodes 112 on the back side of the back-contact solar cell 11 to be in contact with the conductive layer 13, which is beneficial for better electrical connection of the first electrodes 111 and the second electrodes 112 to form a short circuit, and is beneficial for better simulating the structure of the back-contact photovoltaic module when performing UV testing in the short-circuit mode.

[0046] In some embodiments, the light-transmitting layer 12 has an average transmittance of 88% to 98% for light with wavelengths of 300nm to 1200nm and an average transmittance of 36% to 92% for light with wavelengths of 300nm to 400nm. Thus, the light-transmitting layer 12 can better simulate the transmittance of light of various wavelengths by the front light-transmitting panel in a back-contact photovoltaic module, which is beneficial for better simulating the structure of the back-contact photovoltaic module during UV testing.

[0047] Understandably, the average transmittance of the light-transmitting layer 12 for light with wavelengths from 300nm to 1200nm can be 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or any value within the range formed by any two of the above values. The average transmittance of the light-transmitting layer 12 for light with wavelengths from 300nm to 400nm can be 36%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55%, 58%, 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 85%, 90%, 92%, or any value within the range formed by any two of the above values.

[0048] The average transmittance refers to the integral average of the transmittance of the light-transmitting layer 12 for all single-wavelength light within a specified wavelength range. This average transmittance can be obtained by conducting transmittance tests at regular intervals within the specified wavelength range and then taking the integral average. Specifically, the transmittance of the light-transmitting layer 12 can be measured at 1 nm intervals within the specified wavelength range, and then the integral average transmittance over the specific wavelength difference range can be calculated. The transmittance of the light-transmitting layer 12 for a specific wavelength can be tested using conventional equipment and methods such as a transmittance meter.

[0049] In this application, the light-transmitting layer 12 can be a single glass layer or a glass composite structure. The glass composite structure can be, but is not limited to, a composite structure of a glass layer and a functional coating, a composite structure of a glass layer and an adhesive film, or a composite structure of a glass layer, a functional coating, and an adhesive film.

[0050] Furthermore, when a light-transmitting layer 12 with a composite structure consisting of a glass layer and a functional coating is used, the glass layer is located on the side of the light-transmitting layer 12 away from the back contact solar cell 11, and the functional coating is located on the side of the light-transmitting layer 12 close to the back contact solar cell 11; when a light-transmitting layer 12 with a composite structure consisting of a glass layer and an adhesive film is used, the glass layer is located on the side of the light-transmitting layer 12 away from the back contact solar cell 11, and the adhesive film is located on the side of the light-transmitting layer 12 close to the back contact solar cell 11; when a light-transmitting layer 12 with a composite structure consisting of a glass layer, a functional coating, and an adhesive film is used, the glass layer is located on the side of the light-transmitting layer 12 away from the back contact solar cell 11, the adhesive film is located on the side of the light-transmitting layer 12 close to the back contact solar cell 11, and the functional coating is located between the glass layer and the adhesive film.

[0051] Understandably, the functional coating can be an antireflective coating, a selective light-transmitting coating, etc., to give the light-transmitting layer 12 a suitable light transmittance. The encapsulant film can be a conventional photovoltaic encapsulant film in the art.

[0052] In some embodiments, the thickness of the light-transmitting layer 12 is 0.5 mm to 5 mm. This facilitates the encapsulation of the back-contact solar cell 11 in conjunction with the backsheet layer 14 and also helps the light-transmitting layer 12 to have suitable light transmittance. It is understood that the thickness of the light-transmitting layer 12 can be 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, 3.8 mm, 4 mm, 4.2 mm, 4.5 mm, 4.8 mm, 5 mm, or any value within the range formed by any two of the above values.

[0053] In some embodiments, the thickness of the backsheet layer 14 is greater than or equal to 1 mm. This facilitates the encapsulation of the back-contact solar cell 11 in conjunction with the light-transmitting layer 12. The thickness of the backsheet layer 14 can be, but is not limited to, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm.

[0054] Please see Figure 2 In some embodiments, the back contact solar cell reliability testing structure 10 further includes an adhesive layer 15 disposed between the conductive layer 13 and the backsheet layer 14. This adhesive layer 15 bonds the conductive layer 13 and the backsheet layer 14 together, which is more conducive to the encapsulation of the back contact solar cell 11.

[0055] In some embodiments, the back-contact solar cell 11 mainly includes a silicon substrate 113, a first doped silicon layer 114, a second doped silicon layer 115, a first electrode 111, and a second electrode 112. The first doped silicon layer 114 and the second doped silicon layer 115 are both disposed on the back side of the silicon substrate 113. The first doped silicon layer 114 and the second doped silicon layer 115 have different doping types and are spaced apart. The first electrode 111 is in contact with the first doped silicon layer 114, and the second electrode 112 is in contact with the second doped silicon layer 115.

[0056] In this configuration, one of the first doped silicon layer 114 and the second doped silicon layer 115 is an N-type doped silicon layer, and the other is a P-type doped silicon layer. Specifically, when the first doped silicon layer 114 is an N-type doped silicon layer, the second doped silicon layer 115 is a P-type doped silicon layer; and when the first doped silicon layer 114 is a P-type doped silicon layer, the second doped silicon layer 115 is an N-type doped silicon layer. The first electrode 111 and the second electrode 112 can each be independently a silver electrode or a copper electrode.

[0057] In some embodiments, a tunneling oxide layer 116 is further disposed between the first doped silicon layer 114 and the silicon substrate 113, and between the second doped silicon layer 115 and the silicon substrate 113. The tunneling oxide layer 116 may be an ultrathin silicon dioxide layer. A passivation layer 117 and an antireflection layer 118 are sequentially stacked on the surfaces of the first doped silicon layer 114 and the second doped silicon layer 115 facing away from the silicon substrate 113. The first electrode 111 contacts the first doped silicon layer 114 through the antireflection layer 118 and the passivation layer 117 on the first doped silicon layer 114; the second electrode 112 contacts the second doped silicon layer 115 through the antireflection layer 118 and the passivation layer 117 on the second doped silicon layer 115. Similarly, the passivation layer 117 and the antireflection layer 118 are also sequentially stacked on the front side of the silicon substrate 113. The material of the passivation layer 117 may be aluminum oxide, and the material of the antireflection layer 118 may be silicon nitride.

[0058] The fabrication method of the back-contact solar cell reliability testing structure 10 according to one embodiment of this application is as follows:

[0059] (1) Cleaning and polishing: In a tank cleaning equipment, the silicon wafer surface is polished and cleaned by the RCA cleaning method to remove metal ions and serration damage on the surface, and silicon substrate 113 is obtained.

[0060] (2) Preparation of tunneling oxide layer and first doped silicon layer: The silicon substrate 113 obtained by polishing and cleaning is placed in LPCVD (Low-Pressure Plasma-Enhanced Chemical Vapor Deposition) equipment, and high-purity oxygen is introduced to grow tunneling oxide layer 116 at 400℃~650℃. Then, high-purity SiH4 is introduced to grow intrinsic polycrystalline silicon layer at 450℃~700℃. Then, the above structure is placed in boron diffusion furnace tube and BCl3 is introduced at 750℃~1050℃ to perform boron diffusion to form P-type polycrystalline silicon layer, which serves as first doped silicon layer 114.

[0061] (3) First laser patterning + alkaline polishing: A portion of the first doped silicon layer 114 is removed by laser, and then the first doped silicon layer 114 and tunnel oxide layer 116 in the laser-acting area are removed by a tank alkaline polishing machine.

[0062] (4) Preparation of tunneling oxide layer and second doped silicon layer: The structure obtained after alkaline polishing is placed in an LPCVD equipment, and high-purity oxygen is introduced to grow a tunneling oxide layer 116 at 400℃~650℃. Then, high-purity SiH4 is introduced to grow an intrinsic polycrystalline silicon layer at 450℃~700℃. The above structure is then placed in a phosphorus diffusion furnace tube and POCl3 is introduced at 850℃~1050℃ for phosphorus diffusion to form an N-type polycrystalline silicon layer, which serves as the second doped silicon layer 115.

[0063] (5) Second laser patterning + alkaline washing: The PSG in the gap area and the corresponding area of ​​the P+poly-Si layer is ablated using a laser. Then, the N+poly-Si, the tunnel oxide layer 116 and part of the silicon substrate 113 in the gap area are removed by a tank alkaline polishing machine.

[0064] (6) Texturing: The boron phosphosilicon glass on the back surface of the silicon substrate 113 due to the boron / phospho glass is removed using a chain HF equipment. In the tank equipment, sodium hydroxide with a volume ratio of 7:1 and additive of type TS40 are used. The temperature is maintained at 80℃ for 7 minutes to rapidly texturize the silicon substrate 113. The thinning amount of the silicon substrate 113 is controlled at 5μm.

[0065] (7) Deposit passivation layer 117: Aluminum oxide is deposited on the light-incident surface and the back-light surface of silicon substrate 113 using ALD (Atomic Layer Deposition) equipment; silicon oxynitride is deposited on the back-light surface using PECVD (Plasma-Enhanced Chemical Vapor Deposition) equipment, and the aluminum oxide and silicon oxynitride on the back-light surface constitute passivation layer 117; a stack of silicon oxide, silicon oxynitride and silicon nitride is deposited on the light-incident surface using PECVD equipment, and the aluminum oxide, silicon oxide and silicon oxynitride on the light-incident surface serve as passivation layer 117, and the silicon nitride layer serves as antireflection layer 118.

[0066] (8) Electrode fabrication:

[0067] (8.1) Electrode paste is printed on the passivation layer 117 on the first doped silicon layer 114 and dried in a drying oven at a temperature of 100℃~300℃.

[0068] (8.2) Electrode paste is printed on the passivation layer 117 on the second doped silicon layer 115 and dried in a drying oven at a temperature of 100℃~300℃.

[0069] (8.3) High-temperature sintering electrode paste: Electrode paste printed by sintering at a peak sintering temperature of 700℃~900℃ to obtain the first electrode 111 and the second electrode 112 respectively;

[0070] (8.4) Light injection: The electrode precursor is heated once, with a peak temperature of 180℃~620℃; the electrode precursor is heated a second time and then irradiated, with a peak temperature of 80℃~320℃ and an energy density of 12kW / m². 2 ~120 kW / m 2 The wavelength of the light is a continuous spectral band of 500nm to 1100nm.

[0071] (9) Short circuit: The conductive layer 13 is brought into contact with the first electrode 111 and the second electrode 112 on the back of the battery cell. The size of the conductive layer 13 is the same as or larger than that of the battery cell.

[0072] (10) Battery encapsulation: The back contact solar cell 11 is encapsulated with a front light-transmitting layer 12 and a back sheet layer 14. This makes the front light-transmitting layer 12 in contact with the front of the back contact solar cell 11, and the back sheet layer 14 in contact with the conductive layer 13 on the back of the back contact solar cell 11.

[0073] Please see Figure 4 One embodiment of this application provides a reliability testing method for back-contact solar cells, the testing method comprising the following steps S100 to S500:

[0074] Step S100: Test the photoelectric conversion efficiency of the back contact solar cell 11 to obtain the initial photoelectric conversion efficiency.

[0075] Step S200: Assemble the back contact solar cell 11 into the back contact solar cell reliability test structure 10 described above.

[0076] Step S300: Place the back contact solar cell reliability test structure 10 in the ultraviolet aging test equipment and use ultraviolet light to irradiate the front side of the back contact solar cell 11 in the back contact solar cell reliability test structure 10 for ultraviolet aging treatment.

[0077] Step S400: Test the photoelectric conversion efficiency of the back contact solar cell 11 in the back contact solar cell reliability test structure 10 after irradiation and ultraviolet aging treatment, and obtain the photoelectric conversion efficiency after ultraviolet aging.

[0078] Step S500: Divide the difference between the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after UV aging by the initial photoelectric conversion efficiency to obtain the UV decay rate of the back contact solar cell 11.

[0079] The back-contact solar cell reliability testing method described above in this application uses the back-contact solar cell reliability testing structure 10 of this application, which can better simulate the structure of the back-contact solar cell 11 after being packaged into a back-contact photovoltaic module and subjected to UV testing in a short-circuit mode. This is beneficial for quickly and accurately testing the reliability of the cells after they are packaged into a back-contact photovoltaic module under ultraviolet irradiation.

[0080] In some specific examples, the lamp type of the ultraviolet aging test equipment is UVA-340 (simulating the 295nm~365nm spectrum of sunlight); the irradiance is 0.55W / m². 2 / nm~0.70W / m 2 / nm; Temperature range: ambient temperature to 65℃ (±2℃ accuracy); Humidity control: condensation / spray system (optional).

[0081] After the back-contact solar cell reliability test structure 10 is assembled, it is placed in the ultraviolet aging test equipment, and the parameters are set as follows:

[0082] Spectral range: 280nm~400nm (ultraviolet band);

[0083] Cumulative irradiance: 60 kWh / m 2 (IEC 61215 MQT 10 requirements)

[0084] Temperature control:

[0085] Irradiation period: 60±3℃ (test structure surface temperature)

[0086] Condensation period: 40±3℃ (simulating nighttime condensation)

[0087] When the cumulative irradiance reaches 60kWh / m 2 Then, the process was stopped, and the photoelectric conversion efficiency of the back contact solar cell 11 after ultraviolet aging was tested. The difference between the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after ultraviolet aging of the back contact solar cell 11 was divided by the initial photoelectric conversion efficiency to obtain the UV decay rate of the back contact solar cell 11. The higher the UV decay rate, the lower the reliability of the back contact solar cell 11 under ultraviolet irradiation.

[0088] A batch of back-contact solar cells 11 with consistent initial photoelectric conversion efficiency were selected for comparative testing. One of the back-contact solar cells 11 was assembled into the back-contact solar cell reliability test structure 10 of this application, and an ultraviolet aging test was conducted according to the above method to test the photoelectric conversion efficiency of the back-contact solar cell 11 after ultraviolet aging. Multiple back-contact solar cells 11 were assembled into a module, and the initial photoelectric conversion efficiency of the module was tested; then, an ultraviolet aging test was conducted according to the same method, and the photoelectric conversion efficiency of the module after ultraviolet aging was tested in short-circuit mode.

[0089] Test results showed that the UV degradation rate of the single back-contact solar cell 11 assembled into the back-contact solar cell reliability test structure 10 before and after UV aging test was approximately 1.20%; the UV degradation rate of the back-contact photovoltaic module before and after UV aging test was approximately 1.30%. The UV degradation rate test results of the back-contact solar cell reliability test structure 10 of this application are basically consistent with the test results of the back-contact solar cell 11 after being packaged into the back-contact photovoltaic module; it can reflect the reliability of the back-contact solar cell 11 after being packaged into the back-contact photovoltaic module well.

[0090] Another back-contact solar cell 11 was subjected to UV aging testing in the traditional open-voltage mode. Its UV degradation rate before and after the UV aging test was approximately 0.50%, which is significantly different from the UV degradation rate of the back-contact photovoltaic module (1.30%). This indicates that the traditional open-voltage mode test at the cell end cannot accurately reflect the reliability of the back-contact solar cell 11 after it is packaged into a back-contact photovoltaic module.

[0091] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims, and the specification and drawings can be used to interpret the content of the claims.

Claims

1. A reliability testing structure for back-contact solar cells, characterized in that, It includes a back contact solar cell, a light-transmitting layer, a conductive layer, and a backsheet layer; the back of the back contact solar cell has a first electrode and a second electrode with opposite polarities, the light-transmitting layer is disposed on the front of the back contact solar cell, the backsheet layer is disposed on the back of the back contact solar cell, the conductive layer is disposed between the back contact solar cell and the backsheet layer, and both the first electrode and the second electrode are in contact with the conductive layer.

2. The back-contact solar cell reliability testing structure according to claim 1, characterized in that, The conductive layer is made of one or more of copper, silver, gold, aluminum, and tin.

3. The back-contact solar cell reliability testing structure according to claim 1, characterized in that, The conductivity of the conductive layer is greater than or equal to 10. 4 S / m.

4. The back-contact solar cell reliability testing structure according to claim 1, characterized in that, The thickness of the conductive layer is 5μm to 100μm.

5. The back-contact solar cell reliability testing structure according to claim 1, characterized in that, Along the thickness direction of the back contact solar cell reliability test structure, the orthogonal projection of the back contact solar cell onto the backsheet layer does not exceed the orthogonal projection range of the conductive layer onto the backsheet layer.

6. The back-contact solar cell reliability testing structure according to any one of claims 1 to 5, characterized in that, The light-transmitting layer has an average transmittance of 88% to 98% for light with wavelengths of 300nm to 1200nm and an average transmittance of 36% to 92% for light with wavelengths of 300nm to 400nm.

7. The back-contact solar cell reliability testing structure according to any one of claims 1 to 5, characterized in that, The thickness of the light-transmitting layer is 0.5mm to 5mm.

8. The back-contact solar cell reliability testing structure according to any one of claims 1 to 5, characterized in that, The thickness of the backsheet layer is greater than or equal to 1 mm.

9. The back-contact solar cell reliability testing structure according to any one of claims 1 to 5, characterized in that, The back-contact solar cell reliability testing structure also includes an adhesive layer, which is disposed between the conductive layer and the backsheet layer.

10. A method for reliability testing of back-contact solar cells, characterized in that, Includes the following steps: The photoelectric conversion efficiency of the back-contact solar cell was tested to obtain the initial photoelectric conversion efficiency; The back-contact solar cell is assembled into a back-contact solar cell reliability test structure as described in any one of claims 1 to 9; The back-contact solar cell reliability test structure was subjected to ultraviolet aging treatment using ultraviolet light. The photoelectric conversion efficiency of the back contact solar cell in the reliability test structure of the back contact solar cell after the ultraviolet aging treatment is tested to obtain the photoelectric conversion efficiency after ultraviolet aging. The UV decay rate of the back-contact solar cell is obtained by dividing the difference between the initial photoelectric conversion efficiency and the photoelectric conversion efficiency after UV aging by the initial photoelectric conversion efficiency.

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