Processing inspection system and method for conductive backboard of back contact photovoltaic cell

Abstract

The invention provides a processing inspection system and method for a conductive backboard of a back contact photovoltaic cell, and relates to the technical field of solar energy, the processing inspection system comprises a probe tool, a high-voltage power supply and a control circuit, the probe tool is divided into a positive electrode probe group and a negative electrode probe group, and the positive electrode probe group and the negative electrode probe group are respectively used for contacting a positive electrode area and a negative electrode area of a conductive backboard metal foil; the high-voltage power supply is used for outputting a high-voltage pulse signal to the probe tool through the control circuit; one end of a probe of a probe tool is connected with a high-voltage power supply, the other end of the probe is in mechanical contact with two electrodes of a metal conductive foil of a conductive back plate, and then the high-voltage power supply applies high voltage to the metal conductive foil through the probe; the tiny metal wire lapped between the positive electrode and the negative electrode of the metal conductive foil cannot bear high voltage and high current and is fused in the air, and then resistance data is read until the resistance data reaches a range meeting requirements, so that the residual metal wire is completely cleaned, and the problem that the metal wire residue is difficult to remove is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar energy, and particularly relates to a processing and inspection system and method for a conductive backplane of a back-contact photovoltaic cell. Background Art

[0002] As a new generation of high-efficiency photovoltaic devices, back-contact photovoltaic cells (BC) effectively eliminate the front grid line occlusion of traditional cells through the full-back layout design of positive and negative electrodes, and show significant advantages in improving the photoelectric conversion efficiency (1-2 percentage points higher than that of conventional PERC cells) and optimizing the component structure design. Its unique appearance feature without main grid not only improves the overall aesthetics of the component, but also significantly improves the long-term reliability by reducing the solder joint stress. It has now become an important technical direction for the high-end development of the photovoltaic industry;

[0003] In the BC component integration process, the interconnection of battery units mainly adopts two schemes: welding with solder tapes and connecting with a conductive backplane. Compared with the traditional solder tape scheme, the conductive backplane technology can achieve the full-black aesthetic effect on the surface of the component while maintaining excellent electrical conductivity through the embedded circuit design, and has higher long-term reliability due to avoiding repeated thermal stress shocks. It has now become the preferred scheme for high-end BC components. However, in the process of industrialization of this technology, it faces a key process bottleneck - the problem of precision circuit forming of the conductive backplane;

[0004] Currently, the mainstream conductive backplane preparation uses the metal foil etching process. The core technology lies in achieving the predetermined circuit pattern through laser engraving or mechanical engraving. Although the laser engraving technology can achieve micron-level processing accuracy, it has two inherent defects: First, the micron-level metal dust generated by the ablation of the high-energy laser on the metal is likely to deposit in the processing area, resulting in the deterioration of the insulation performance between circuits; Second, limited by the laser power and scanning path, the processing efficiency is difficult to exceed 20 mm / s, restricting the mass production economy. While mechanical engraving can improve the processing speed through physical cutting (up to more than 50 mm / s), the ductile chips generated by the contact between the tool and the metal foil will form micron-level metal wire residues. If these residues are not effectively removed, it will cause bridging short circuits between adjacent circuits, and in severe cases, the component power attenuation can exceed 15%; It should be particularly noted that the detection and removal of metal wire residues constitute the core technical bottleneck in the manufacturing of conductive backplanes; Conventional optical detection has a significant risk of missed detection due to the small size of the metal wires (usually <10 μm); The existing air blowing / brush cleaning process has a cleaning rate of less than 60% for the ductile chips with strong adhesion. The residues are more likely to embed in the encapsulation material under the action of high temperature and high pressure in the subsequent lamination process to form a permanent short circuit channel. This technical problem directly restricts the yield improvement (industry average level <85%) and cost control of the conductive backplane process, becoming the key obstacle restricting the large-scale industrialization of BC components. Therefore, the present invention proposes a processing and inspection system and method for the conductive backplane of a back-contact photovoltaic cell to solve the problems existing in the prior art. Summary of the Invention

[0005] In view of the above problems, the present invention proposes a processing and inspection system and method for the conductive backplane of a back-contact photovoltaic cell. One end of the probe of the probe tooling of the processing and inspection system for the conductive backplane of the back-contact photovoltaic cell is connected to a high-voltage power supply, and the other end mechanically contacts the two electrodes of the metal conductive foil of the conductive backplane. Then, the high-voltage power supply applies a high voltage to the metal conductive foil through the probe. The tiny metal wires lapped between the positive and negative poles of the metal conductive foil cannot withstand the high voltage and high current and are melted in the air. Then, the resistance data is read until it reaches the required range, so that the remaining metal wires are completely cleared.

[0006] To achieve the object of the present invention, the present invention is realized through the following technical solutions: A processing and inspection system for the conductive backplane of a back-contact photovoltaic cell, including a probe tooling, a high-voltage power supply, and a control circuit. The probe tooling is divided into a positive probe group and a negative probe group, which are respectively used to contact the positive electrode area and the negative electrode area of the metal foil of the conductive backplane;

[0007] The high-voltage power supply is used to output a high-voltage pulse signal to the probe tooling through the control circuit, and adjust the voltage magnitude to achieve accurate melting of the lapped metal wires, and at the same time measure the resistance at this time to determine whether the product meets the requirements.

[0008] A further improvement is that the positive electrode probe group and the negative electrode probe group are conductive.

[0009] A further improvement is that the high voltage power supply is a megohmmeter or other power supply that can output a voltage of 1000-3000 volts.

[0010] A further improvement is that when the high voltage power supply is a megohmmeter, a hand-cranked megohmmeter is selected, and the output voltage is controlled by controlling the speed and strength of the hand-cranking to achieve accurate fusing of the overlapping metal wire.

[0011] A processing and inspection method for a back-contact photovoltaic cell conductive back plate comprises the following steps:

[0012] Lay the processed conductive backplane flat on an insulating flat table, and press the test probe tooling on the metal foil;

[0013] Press the positive and negative electrodes of the probe fixture onto the positive and negative electrode areas of the metal foil respectively;

[0014] After pressing into place, the control circuit sends a signal to the high-voltage power supply, outputting a high-voltage current pulse to fuse the remaining metal chips;

[0015] After each pulse, the current between the positive and negative regions of the foil is measured and the resistance is calculated;

[0016] After obtaining the resistance, make a judgment to determine whether the product meets the requirements.

[0017] A further improvement is that the probe of the probe tooling is made of copper, silver, gold or an alloy of multiple metals.

[0018] A further improvement is that the contact area between the probe of the probe fixture and the metal foil is controlled to be above 3 square centimeters.

[0019] A further improvement is that the probe head of the probe tooling is flat.

[0020] A further improvement is that when high voltage current pulses are output, the control voltage is 1000 to 3000 volts and each pulse lasts for 0.5 to 2 seconds.

[0021] A further improvement is that after the resistance is obtained, a judgment is made. When the resistance reaches 50 megohms, it meets the requirements and the process is terminated. When the resistance is still less than 50 megohms after 10 pulses, it is judged as a defective product and the process is terminated.

[0022] The beneficial effects of the present invention are:

[0023] 1. One end of the probe of the probe tooling of the present invention is connected to a high-voltage power supply, and the other end mechanically contacts two electrodes of the metal conductive foil of the conductive backplane. Then, the high-voltage power supply applies a high voltage to the metal conductive foil through the probe. The tiny metal wire lapped between the positive and negative poles of the metal conductive foil cannot withstand the high voltage and high current and fuses in the air. Then, the resistance data is read until it reaches the required range, so that the remaining metal wire is completely cleaned, solving the problem that the metal wire residue is not easy to remove during the production process of the conductive metal foil.

[0024] 2. The present invention uses a large current to directly fuse the residual metal wire that may cause a short circuit, integrating the functions of removing the metal wire and detecting the metal wire residue at low cost and high efficiency. It not only significantly improves the production efficiency, but also increases the production yield from less than 85% at present to more than 95%, greatly reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the conductive backplane structure;

[0026] Figure 2 It is a flow chart of the present invention;

[0027] Figure 3 It is a schematic diagram of the probe tooling of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with embodiments. These embodiments are only used to explain the present invention and do not constitute a limitation to the protection scope of the present invention.

[0029] Embodiment 1

[0030] According to Figure 1 、 2 、and as shown in FIG. 3, this embodiment proposes a processing and inspection system for the conductive backplane of a back-contact photovoltaic cell, including a probe tooling, a high-voltage power supply, and a control circuit. The probe tooling is divided into a positive probe group and a negative probe group, which are respectively used to contact the positive region and the negative region of the metal foil of the conductive backplane;

[0031] The high-voltage power supply is used to output a high-voltage pulse signal to the probe tooling through the control circuit and adjust the voltage magnitude to achieve accurate fusing of the lapped metal wire, and at the same time measure the resistance at this time to determine whether the product meets the requirements.

[0032] The positive probe group and the negative probe group have conductivity. The high-voltage power supply is a megohmmeter or other power supply that can output a voltage of 1000 - 3000 volts. When the high-voltage power supply is a megohmmeter, a hand-cranked megohmmeter is selected, and the voltage magnitude output is controlled by controlling the speed and strength of hand-cranking to achieve accurate fusing of the lapped metal wire.

[0033] Among them, the probe tooling needs to be designed according to the pattern of the conductive backplane, and is divided into a positive probe group and a negative probe group, which are respectively in contact with the positive and negative regions of the metal foil of the conductive backplane. The probes are required to have good electrical conductivity. A megohmmeter or other power source is used to output a high-voltage electrical signal. There are generally hand-cranked megohmmeters and digital megohmmeters. The hand-cranked megohmmeter has the advantages of low cost and flexible use, and is preferred in this solution. Workers can control the speed and strength of the hand-cranking to control the magnitude of the output voltage, so as to accurately fuse the overlapping metal wires. In addition to the megohmmeter, other power sources that can output voltages of 1000 - 3000 volts are also applicable. The high-voltage power source can output high-voltage pulse signals through the control circuit to fuse the overlapping metal wires. At the same time, it is also necessary to measure the resistance at this time to determine whether the product meets the requirements. The solution of the high-voltage power source with the control circuit can achieve a higher degree of automation, is suitable for mass production, and further improves efficiency and production capacity. Figure 1 It is the conductive backplane structure of a typical back-contact photovoltaic cell. Among them, parts A and B correspond to the positive and negative electrodes of the solar cell, and good insulation is required between the two. Its manufacturing method is to engrave on a complete metal conductive foil, and then tear off the metal between parts A and B (the typical distance between parts A and B is about 2 mm) to achieve isolation between regions A and B. This processing method usually results in the residue of micron-level metal chips, affecting the insulation between parts A and B. Therefore, a high-voltage pulse signal is output to the probe tooling through the cooperation of the high-voltage power source and the control circuit, and the voltage magnitude is adjusted to accurately fuse the overlapping metal wires.

[0034] Embodiment 2

[0035] According to Figure 1 、 2 、and Figure 3, this embodiment proposes a processing and inspection method for the conductive backplane of a back-contact photovoltaic cell, including the following steps:

[0036] Lay the conductive metal foil after scribing flat on the insulating operating table.

[0037] Press the probes of the probe tooling onto the positive and negative electrodes of the conductive metal foil.

[0038] Start the hand-cranked megohmmeter, output high voltage, and observe the resistance value. If the resistance is greater than 10 megohms, the product meets the insulation requirements and is packed and stored in the warehouse; if the resistance is less than 10 megohms, continue to crank the megohmmeter and continuously output high voltage to cause the fine metal wire overlapping between the positive and negative electrodes of the conductive foil to fuse. Until the resistance value reaches 10 megohms or more. If the resistance requirement cannot be met all the time, the product is processed according to the downgrading.

[0039] Pack and store the conductive foil according to the output grading signal.

[0040] The probe of the probe tooling is made of copper, silver, gold or an alloy of multiple metals. The contact area between the probe of the probe tooling and the metal foil is controlled to be more than 3 square centimeters. The head of the probe of the probe tooling is flat.

[0041] The manual inspection solution features low cost and high flexibility, and is suitable for small-batch trial production.

[0042] Example 3

[0043] According to Figure 1 、 2 As shown in FIGS. 3, this embodiment proposes a processing and inspection method for the conductive backplane of a back-contact photovoltaic cell, including the following steps:

[0044] The conductive metal foil after scribing is flattened and unfolded on an insulating operating table.

[0045] The probes of the probe tooling are pressed onto the positive and negative electrodes of the conductive metal foil.

[0046] Start the constant-voltage power supply, and according to the control program, start to output a pulsed voltage signal. While fusing the residual metal wire, measure the resistivity between the positive and negative electrodes. After 10 high-voltage pulses of processing and testing, output a signal indicating whether the product is qualified. When outputting the high-voltage current pulse, the control voltage is 1000 - 3000 volts, and the duration of each pulse is 0.5 - 2 seconds. After obtaining the resistance, make a judgment. When the resistance reaches 50 megohms, it meets the requirements. When the resistance is still less than 50 megohms after 10 pulses, it is determined as a defective product.

[0047] Package and store the conductive foil according to the output grading signal

[0048] The probe of the probe tooling is made of copper, silver, gold or an alloy of multiple metals. The contact area between the probe of the probe tooling and the metal foil is controlled to be more than 3 square centimeters. The head of the probe of the probe tooling is flat.

[0049] The fully automated inspection solution features high automation and large production volume, and is suitable for large-batch production.

[0050] The processing and inspection system and method for the conductive backplane of a back-contact photovoltaic cell connect one end of the probe of the probe tooling to a high-voltage power supply and the other end mechanically contacts the two electrodes of the metal conductive foil of the conductive backplane. Then, the high-voltage power supply applies a high voltage to the metal conductive foil through the probe. The tiny metal wire lapped between the positive and negative poles of the metal conductive foil cannot withstand the high voltage and high current and fuses in the air. Then, the resistance data is read until it reaches the required range, so that the remaining metal wire is completely cleared, solving the problem that the residual metal wire is not easy to remove during the production process of the conductive metal foil. The present invention directly uses a large current to fuse the residual metal wire that may cause a short circuit, integrating the functions of removing the metal wire and inspecting the residual metal wire with low cost and high efficiency. It not only significantly improves the production efficiency, but also increases the production yield from less than 85% currently to more than 95%, greatly reducing the cost.

[0051] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A processing and inspection system for a back-contact photovoltaic cell conductive backplane, comprising a probe tooling, a high voltage power supply and a control circuit, characterized in that: The probe tooling is divided into a positive electrode probe group and a negative electrode probe group, which are used to contact the positive electrode area and the negative electrode area of ​​the conductive back plate metal foil respectively; The high-voltage power supply is used to output a high-voltage pulse signal to the probe fixture through a control circuit, and adjust the voltage to achieve accurate fusing of the overlapping metal wires, while measuring the resistance at this time to determine whether the product meets the requirements.

2. A processing and inspection system for a back-contact photovoltaic cell conductive backplane according to claim 1, characterized in that: The positive electrode probe group and the negative electrode probe group are conductive.

3. A processing and inspection system for a back-contact photovoltaic cell conductive backplane according to claim 1, characterized in that: The high voltage power supply is a megohmmeter or other power supply that can output a voltage of 1000-3000 volts.

4. A processing and inspection system for a back-contact photovoltaic cell conductive backplane according to claim 1, characterized in that: When the high-voltage power supply is a megohmmeter, a hand-cranked megohmmeter is selected, and the output voltage is controlled by controlling the speed and strength of the hand-cranking to achieve accurate fusing of the overlapping metal wire.

5. A processing and inspection method for a back-contact photovoltaic cell conductive back sheet, using a processing and inspection system for a back-contact photovoltaic cell conductive back sheet as described in any one of claims 1 to 4, characterized in that: The following steps are involved: Lay the processed conductive backplane flat on an insulating flat table, and press the test probe tooling on the metal foil; Press the positive and negative electrodes of the probe fixture onto the positive and negative electrode areas of the metal foil respectively; After pressing into place, the control circuit sends a signal to the high-voltage power supply, outputting a high-voltage current pulse to fuse the remaining metal chips; After each pulse, the current between the positive and negative regions of the foil is measured and the resistance is calculated; After obtaining the resistance, make a judgment to determine whether the product meets the requirements.

6. A processing and inspection method for a back-contact photovoltaic cell conductive back sheet according to claim 5, characterized in that: The probe of the probe tool is copper, silver, gold or an alloy of multiple metals.

7. A processing and inspection method for a back-contact photovoltaic cell conductive back sheet according to claim 6, characterized in that: The contact area between the probe of the probe fixture and the metal foil is controlled to be more than 3 square centimeters.

8. A processing and inspection method for a back-contact photovoltaic cell conductive back sheet according to claim 7, characterized in that: The probe head of the probe tool is flat.

9. The method for processing and inspecting a back-contact photovoltaic cell conductive back sheet according to claim 5, characterized in that: When outputting high-voltage current pulses, the control voltage is 1000 to 3000 volts, and each pulse lasts for 0.5 to 2 seconds.

10. The method for processing and inspecting a back-contact photovoltaic cell conductive back sheet according to claim 5, characterized in that: After the resistance is obtained, a judgment is made. When the resistance reaches 50 megohms, it meets the requirements and the process is terminated. When the resistance is still less than 50 megohms after 10 pulses, it is judged as a defective product and the process is terminated.

Images