WO2014173330A1 - Welding strip for solar battery and solar battery assembly - Google Patents

Welding strip for solar battery and solar battery assembly Download PDF

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Publication number
WO2014173330A1
WO2014173330A1 PCT/CN2014/076416 CN2014076416W WO2014173330A1 WO 2014173330 A1 WO2014173330 A1 WO 2014173330A1 CN 2014076416 W CN2014076416 W CN 2014076416W WO 2014173330 A1 WO2014173330 A1 WO 2014173330A1
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WIPO (PCT)
Prior art keywords
strip
welding
solar
welding strip
solar battery
Prior art date
Application number
PCT/CN2014/076416
Other languages
French (fr)
Inventor
Zhanfeng Jiang
Shengya Wang
Xiang Sun
Juan HU
Shuili FANG
Junchao CAO
Original Assignee
Shenzhen Byd Auto R&D Company Limited
Byd Company Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
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Application filed by Shenzhen Byd Auto R&D Company Limited, Byd Company Limited filed Critical Shenzhen Byd Auto R&D Company Limited
Publication of WO2014173330A1 publication Critical patent/WO2014173330A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
    • H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
    • H01L31/0508—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module the interconnection means having a particular shape
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy

Definitions

  • Exemplary embodiments of the present disclosure relate generally to a field of solar battery, and more particularly to a welding strip for solar battery and a solar battery assembly having the same.
  • a single crystal silicon solar cell tends to break and is low in power generation.
  • a plurality of solar cells are connected and packaged to form an assembly.
  • a plurality of solar cells are connected to form a battery pack, then a plurality of battery packs are arranged into an array, in which the solar cells in the same row are connected in series and the solar cells in different rows are connected in parallel.
  • a back electrode of one of the solar cells is connected with a front electrode of an adjacent solar cell by means of a thin welding strip.
  • the welding strip's width gradually changes with a variety of a current density on the front surface of the solar battery assembly, the welding strip's width increases with an increase of the current density, and decreases with a decrease of the current density.
  • the width of the welding strip on the front surface becomes smaller gradually, and the welding area is an isosceles triangle, a right triangle or an isosceles trapezoid in shape.
  • the width of the welding strip electrically connected with a back electrode is equal to that of the widest portion of the welding strip electrically connected with a front electrode, which is a rectangle in shape, as shown in Fig. 1.
  • the high welding temperature area of a back surface of a solar cell is much larger than that of a front surface of a solar cell.
  • a solar cell is connected with a welding strip by welding under a high temperature, and cooled to the ambient temperature.
  • the size of the front surface is different from that of the back surface after welding, and the heat-expansion and cold-contraction coefficient of the copper substrate welding strip is different from that of the silicon, therefore a stress is generated.
  • Two ends of the solar cell bend towards the back surface, and the middle portion of the solar cell hunches towards the front surface, therefore the solar cell becomes friable and tends to break during the process of laying and lamination, so that the performance and the electrical property of the solar assembly decreases.
  • a welding strip for solar battery includes a first strip segment having an arc section, the number of the arc section is n, the difference between an arc length of the arc section and a chord length of the arc section is AL, 0.4 mm ⁇ n* AL ⁇ 1.0 mm, and n is an integer.
  • the number of the arc section n is 2 to 5.
  • a sum of the arc length of the arc sections is 30.4 mm to 38.5 mm.
  • a sum of the chord length of the arc sections is 30 mm to 37.5 mm.
  • the welding strip further includes a second strip segment connected to an end of the first strip segment.
  • the first and second strip segments are integrally formed.
  • a width of the second strip segment is decreased gradually along a direction away from the first strip segment.
  • a solar battery assembly includes a plurality of solar cells and a plurality of welding strips according to the above and configured to connect the plurality of solar cells with each other.
  • each solar cell has a front surface and a back surface and includes a front electrode disposed on the front surface and a back electrode disposed on the back surface
  • the first strip segment of the welding strip is connected to a back electrode of a first solar cell of the plurality of the solar cells
  • the second strip segment of the welding strip is connected to a front electrode of a second solar cell of the plurality of the solar cells adjacent to and located at a downstream of the first solar cell.
  • a position of the arc section is corresponding to a position of the back electrode.
  • Fig. 1 is a schematic view of a welding strip for solar battery in the related art
  • Fig. 2 is a schematic view of a welding strip according to embodiments of the present disclosure.
  • a welding strip for solar battery includes a first strip segment 1, and the first strip segment 1 includes an arc section 2, the number of arc sections 2 is n, and n is an integer.
  • a difference between an arc length of the arc section 2 and a chord length of the arc section 2 is AL, in which 0.4 ram ⁇ n*AL ⁇ 1.0 mm, and n is an integer.
  • a solar cell is connected with a welding strip by welding under a high temperature, then is cooled to an ambient temperature.
  • the heat-expansion and cold-contraction coefficient of a copper substrate of the welding strip is different from that of a silicon substrate of the solar battery, therefore a stress is generated due to the cooling.
  • Two ends of the solar cell bend towards the back surface (the light shielding surface), and the middle portion of the solar cell hunches towards the front surface (the light receiving surface).
  • the shrinkage of the welding strip may be compensated, the stress is decreased and the deformation of the solar cell, so that the crack is reduced during the process of laying and lamination.
  • Formula (1) is a computational formula of coefficient of linear expansion of the substrate when the temperature is increased:
  • Lt is the length of the substrate at a temperature of t ° C
  • L0 is the length of the substrate at a temperature of 0 ° C .
  • L0 143.5mm
  • a coefficient of linear expansion of copper is ⁇ ⁇ ⁇ "6 ! ⁇ "1
  • a coefficient of linear expansion of polycrystal cell is 2.32x 10 "6 ° C _1 .
  • a compensation quantity is obtained, i.e., the range of n-
  • the number of the arc section n is from 2 to 5.
  • the sum of the arc length of the arc sections is 30.4 mm to 38.5 mm. If the arc length is too short, a plastic deformation of the welding strip tends to occur, so that the deformation of the welding strip is hard to compensate; if the arc length is too long, the stress of the solar cell may be increased, so that the solar cell tends to break.
  • the sum of the chord length of the arc sections 2 is 30 mm to 37.5 mm.
  • chord length is too long, the stress of the grid line, sucker and welding base may be interfered with each other, thus decreasing the compensation effect.
  • the welding strip for solar battery further includes a second strip segment 3 connected to an end of the first strip segment 1 in a length direction of the welding strip, and the width of the second strip segment 3 is decreased gradually along a direction away from the first strip segment 1, i.e., the width of the 3 gradually changes with a variety of a current density.
  • the first and second strip segments may be formed integrally.
  • the arc section 2 is formed by pressing the welding strip when the welding strip is cut by an automatic welding machine.
  • a solar battery assembly according to embodiments of the present disclosure is provided.
  • the solar battery assembly includes a plurality of solar cells and a plurality of welding strips. Each of the solar cells has a front surface and a back surface.
  • the welding strips are configured to connect the plurality of solar cells with each other and/or connect the solar cell with a load.
  • each solar cell includes a front electrode disposed on the front surface and a back electrode disposed on the back surface.
  • the first strip segment 1 of the welding strip is connected to a back electrode of a first solar cell of the plurality of the solar cells
  • the second strip segment 3 of the welding strip is connected to a front electrode of a second solar cell of the plurality of the solar cells adjacent to and located at a downstream of the first solar cell.
  • a position of the arc section 2 may be corresponding to a position of the back electrode.
  • the linear expansion may be compensated, the stress due to heat-expansion and cold-contraction coefficient is decreased and the possibility of the deformation of the solar cell due to the high welding temperature is reduced. Therefore, a crack or a hidden crack due to welding and laminating can reduced or eliminated
  • a polycrystalline POP cell with a size of 156mmx l56mmx20C ⁇ m is taken as an example.
  • the polycrystalline cell has three main grid lines, and four segments of back electrode, a size of each segment of the back electrode is 24.5mmx3mm.
  • the basis material of the conductive strip used in this embodiment is a tin-coated copper strip with a size of 0.2mm (thickness) x2.5mm
  • a rolled tin-coated copper strip is disposed into an automatic series welding machine with a pressing mold, then solar cells are disposed in the automatic series welding machine, so that the solar cells are welded in series with the tin-coated copper strip which has been processed by a pressing treatment, so as to obtain the cell strings.
  • the tin-coated copper strip had three arc sections with a total arc length of 31mm and a total chord length of
  • the cell string was disposed on the EVA (Ethylene Vinyl Acetate ) of the glass plate, then spaces between the cell strings are set with high temperature adhesive tapes, and the cell strings are connected with each other by bus bars, then the connected cell strings are covered with EVA and TPE plates.
  • EVA Ethylene Vinyl Acetate
  • the redundant EVA and TPE plate of the laminated product may be cut off, a frame is assembled, a junction box is connected, and finally a solar battery assembly is obtained after curing and cleaning.
  • a rolled tin-coated copper strip is disposed into an automatic series welding machine with a pressing mould, then solar cells are disposed in the automatic series welding machine, so that the solar cells are welded in series with the tin-coated copper strip which has been processed by a pressing treatment, so as to obtain the cell strings.
  • the tin-coated copper strip has three arc sections having a total arc length of 31mm and a total chord length of 30.2mm.
  • a P6-30 toughened glass is disposed on a laying table, and EVA is disposed on the toughened glass, in which a size of the EVA is slightly larger than that of the toughened glass.
  • the cell strings are arranged above EVA according to predetermined spaces, using 3M high temperature adhesives, with the light receiving surfaces of the solar cells facing down.
  • the cell strings are arranged in series with a tin-coated bus bar having a size of 6mmx0.45mm.
  • the bus bars of the leading-out terminals of the positive and negative electrodes were L-shaped.
  • EVA and TPE cover the cell strings connected in series.
  • a cut with a length of 95mm extends from the central position of the leading-out terminals to both sides thereof.
  • a distance between a cut and a shorter edge of an end of the back plate is about 70mm, so that the leading-out terminals of the positive electrode and the negative electrode of the bus bar were extended out through the cut.
  • a photovoltaic assembly laminated product is obtained by testing crack with an EL tester, laminating, cooling the laminated product, and cutting off the redundant EVA and TPE plate of the laminated product formed by the pressing welding strip and the POP solar cell.
  • the above assembly is installed into an aluminum frame, then the frame is connected with the back plate and connections between the frame and the back plate is filled with sealant uniformly.
  • the sealant is also filled in the cuts of the TPE back plate of the leading-out terminal of the positive electrode and the negative electrode of the bus bar.
  • the sealant is also filled in the specified position of junction box.
  • the un-cured assembly is positioned in the curving apparatus, under a temperature of 25 ° C + 2 ° C and a humidness of 70% ⁇ 10%), for more than four hours.
  • the cured assembly is disposed on a cleaning device to clean a leftover adhesive and dirt, and the leading-out terminals of the positive electrode and the negative electrode of the bus bar are connected to the junction box before closing the cover of the junction box.
  • the positive electrode and the negative electrode are connected to the junction box to form a final solar battery assembly Al .
  • the battery assembly is formed by the method substantially similar to EMBODIMENT 1. The only difference is that, the number of the arc sections is three, the total arc length is 38.5mm, and the total chord length is 37.5mm. Therefore, a final solar battery assembly A2 is formed.
  • the battery assembly is formed by the method substantially similar to EMBODIMENT 1. The only difference is that, the number of the arc sections is three, the total arc length is 33.5mm, and the total chord length is 32.5mm. Therefore, a final solar battery assembly A3 is formed.
  • the battery assembly is formed by the method substantially similar to EMBODIMENT 1. The only difference is that, the number of the arc sections is five, the total arc length is 33.2mm, and the total chord length is 32.5mm. Therefore, a final solar battery assembly A4 is formed.
  • the battery assembly is formed by the method substantially similar to EMBODIMENT 1. The only difference is that, the number of the arc sections is four, the total arc length is 34.5mm, and the total chord length is 33.9mm. Therefore, a final solar battery assembly A5 is formed.
  • the battery assembly is formed by the method substantially similar to EMBODIMENT 1. The only difference is that, the number of the arc sections is two, the total arc length is 30.4mm, and the total chord length is 30mm. Therefore, a final solar battery assembly A6 is formed.
  • a polycrystalline POP cell with a size of 156 ⁇ ⁇ 156 ⁇ ⁇ 200 ⁇ is taken as an example, and the polycrystalline cell had three main grid lines, and four pieces of back electrode, a size of each piece was of 24.5mmx3mm.
  • the basis material of the conductive strip used in this example is a tin-coated copper strip with a size of 0.2mm> ⁇ 2.5mm, in which the copper is 0.18 mm, and the tin-coated layer is 0.2 mm.
  • a rolled tin-coated copper strip is disposed into an automatic series welding machine with a pressing mould, then solar cells are disposed in the automatic series welding machine, so that the solar cells are welded in series with the tin-coated copper strip which has been processed by a pressing treatment, so as to obtain the cell strings.
  • the welding strip is connected with the cells together to form the cell string which is disposed on the EVA of the glass, then spaces between the cell strings are set with high temperature adhesive tapes, and the cell strings are connected with each other by bus bars, then the connected cell strings are covered by EVA and TPE plates.
  • the redundant EVA and TPE plate of the laminated product may be cut off, a frame is assembled, a junction box is connected, and finally a solar battery assembly is obtained after curing and cleaning.
  • the solar battery assemblies according to EMBODIMENTS 1-6 and COMPARING EXAMPLE are tested under a same ambient temperature respectively, by using a solar battery assembly test apparatus with a crack tester. Results are list in Table 1.

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Abstract

A welding strip for solar battery includes a first strip segment (1) including an arc section (2), wherein the number of the arc section (2) is n, the difference between an arc length of the arc section (2) and a chord length of the arc section (2) is △L, 0.4mm ≤ n⋅△L ≤ 1.0mm, and n is an integer.

Description

WELDING STRIP FOR SOLAR BATTERY AND SOLAR BATTERY ASSEMBLY
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority to, and benefits of Chinese Patent Application No. 201320220757.2, filed with the State Intellectual Property Office of China on April 27, 2013, the entire content of which is incorporated herein by reference.
FIELD
Exemplary embodiments of the present disclosure relate generally to a field of solar battery, and more particularly to a welding strip for solar battery and a solar battery assembly having the same.
BACKGROUND
Since a single crystal silicon solar cell (solar panel) tends to break and is low in power generation. In practice, a plurality of solar cells are connected and packaged to form an assembly. For example, a plurality of solar cells are connected to form a battery pack, then a plurality of battery packs are arranged into an array, in which the solar cells in the same row are connected in series and the solar cells in different rows are connected in parallel. For the serial connection, a back electrode of one of the solar cells is connected with a front electrode of an adjacent solar cell by means of a thin welding strip.
The welding strip's width gradually changes with a variety of a current density on the front surface of the solar battery assembly, the welding strip's width increases with an increase of the current density, and decreases with a decrease of the current density. The width of the welding strip on the front surface becomes smaller gradually, and the welding area is an isosceles triangle, a right triangle or an isosceles trapezoid in shape. The width of the welding strip electrically connected with a back electrode is equal to that of the widest portion of the welding strip electrically connected with a front electrode, which is a rectangle in shape, as shown in Fig. 1.
The high welding temperature area of a back surface of a solar cell is much larger than that of a front surface of a solar cell. A solar cell is connected with a welding strip by welding under a high temperature, and cooled to the ambient temperature. The size of the front surface is different from that of the back surface after welding, and the heat-expansion and cold-contraction coefficient of the copper substrate welding strip is different from that of the silicon, therefore a stress is generated. Two ends of the solar cell bend towards the back surface, and the middle portion of the solar cell hunches towards the front surface, therefore the solar cell becomes friable and tends to break during the process of laying and lamination, so that the performance and the electrical property of the solar assembly decreases.
SUMMARY
a welding strip for solar battery according to embodiments of the present disclosure includes a first strip segment having an arc section, the number of the arc section is n, the difference between an arc length of the arc section and a chord length of the arc section is AL, 0.4 mm^n* AL^ 1.0 mm, and n is an integer.
In some embodiments, 0.4 5mm:¾n*AL:¾0.65 mm.
In some embodiments, the number of the arc section n is 2 to 5.
In some embodiments, a sum of the arc length of the arc sections is 30.4 mm to 38.5 mm.
In some embodiments, a sum of the chord length of the arc sections is 30 mm to 37.5 mm.
In some embodiments, the welding strip further includes a second strip segment connected to an end of the first strip segment.
In some embodiments, the first and second strip segments are integrally formed.
In some embodiments, a width of the second strip segment is decreased gradually along a direction away from the first strip segment.
A solar battery assembly according to embodiments of the present disclosure includes a plurality of solar cells and a plurality of welding strips according to the above and configured to connect the plurality of solar cells with each other.
In some embodiments, each solar cell has a front surface and a back surface and includes a front electrode disposed on the front surface and a back electrode disposed on the back surface, the first strip segment of the welding strip is connected to a back electrode of a first solar cell of the plurality of the solar cells, and the second strip segment of the welding strip is connected to a front electrode of a second solar cell of the plurality of the solar cells adjacent to and located at a downstream of the first solar cell.
In some embodiments, a position of the arc section is corresponding to a position of the back electrode.
Additional aspects and advantages of embodiments of present disclosure will be given in part in the following descriptions, become apparent in part from the following descriptions, or be learned from the practice of the embodiments of the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other aspects and advantages of embodiments of the present disclosure will become apparent and more readily appreciated from the following descriptions made with reference to the drawings, in which:
Fig. 1 is a schematic view of a welding strip for solar battery in the related art;
Fig. 2 is a schematic view of a welding strip according to embodiments of the present disclosure.
DETAILED DESCRIPTION
The aforementioned features and advantages of the present invention as well as the additional features and advantages thereof will be further clearly understood hereafter as a result of a detailed description of the following embodiments when taken in conjunction with the drawings.
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 invention belongs. In case of conflict, the specification, including definitions, will control.
As shown in Fig. 2, a welding strip for solar battery is provided. The welding strip for solar battery includes a first strip segment 1, and the first strip segment 1 includes an arc section 2, the number of arc sections 2 is n, and n is an integer. A difference between an arc length of the arc section 2 and a chord length of the arc section 2 is AL, in which 0.4 ram^n*AL^ 1.0 mm, and n is an integer.
A solar cell is connected with a welding strip by welding under a high temperature, then is cooled to an ambient temperature. The heat-expansion and cold-contraction coefficient of a copper substrate of the welding strip, is different from that of a silicon substrate of the solar battery, therefore a stress is generated due to the cooling. Two ends of the solar cell bend towards the back surface (the light shielding surface), and the middle portion of the solar cell hunches towards the front surface (the light receiving surface). By provision of the arc section, the shrinkage of the welding strip may be compensated, the stress is decreased and the deformation of the solar cell, so that the crack is reduced during the process of laying and lamination. Formula (1) is a computational formula of coefficient of linear expansion of the substrate when the temperature is increased:
a=(Lt- LOy (L0 · t) (1),
in which, ais coefficient of linear expansion; Lt is the length of the substrate at a temperature of t°C ; L0 is the length of the substrate at a temperature of 0°C .
According to the embodiments of the present disclosure, L0=143.5mm, a coefficient of linear expansion of copper is Π^χ ΙΟ"6!^"1; a coefficient of linear expansion of polycrystal cell is 2.32x 10"6 °C_1. When only linear expansion lengthwise is considered, a difference AL between the welding strip and the silicon plate is calculated under temperatures from 230°C to 25 °C .
AL= ( a copper- a silicon) X (t230-t25 ) X LO
= ( 17.9-2.32) X (230-25 ) X 143.5 X 10"6 =0.458 mm.
According to the calculation above, a compensation quantity is obtained, i.e., the range of n-
AL.
In some embodiments, 0.4 mm^n*AL^ 1.0 mm.
In some embodiments, the number of the arc section n is from 2 to 5.
In some embodiments, the sum of the arc length of the arc sections is 30.4 mm to 38.5 mm. If the arc length is too short, a plastic deformation of the welding strip tends to occur, so that the deformation of the welding strip is hard to compensate; if the arc length is too long, the stress of the solar cell may be increased, so that the solar cell tends to break.
In some embodiments, the sum of the chord length of the arc sections 2 is 30 mm to 37.5 mm.
If the chord length is too long, the stress of the grid line, sucker and welding base may be interfered with each other, thus decreasing the compensation effect.
In some embodiments of the present disclosure, the welding strip for solar battery further includes a second strip segment 3 connected to an end of the first strip segment 1 in a length direction of the welding strip, and the width of the second strip segment 3 is decreased gradually along a direction away from the first strip segment 1, i.e., the width of the 3 gradually changes with a variety of a current density. The first and second strip segments may be formed integrally.
The arc section 2 is formed by pressing the welding strip when the welding strip is cut by an automatic welding machine. A solar battery assembly according to embodiments of the present disclosure is provided. The solar battery assembly includes a plurality of solar cells and a plurality of welding strips. Each of the solar cells has a front surface and a back surface.
The welding strips are configured to connect the plurality of solar cells with each other and/or connect the solar cell with a load.
In some embodiments, each solar cell includes a front electrode disposed on the front surface and a back electrode disposed on the back surface. The first strip segment 1 of the welding strip is connected to a back electrode of a first solar cell of the plurality of the solar cells, and the second strip segment 3 of the welding strip is connected to a front electrode of a second solar cell of the plurality of the solar cells adjacent to and located at a downstream of the first solar cell.
A position of the arc section 2 may be corresponding to a position of the back electrode.
By forming the arc section 2, the linear expansion may be compensated, the stress due to heat-expansion and cold-contraction coefficient is decreased and the possibility of the deformation of the solar cell due to the high welding temperature is reduced. Therefore, a crack or a hidden crack due to welding and laminating can reduced or eliminated
EMBODIMENT 1
A polycrystalline POP cell with a size of 156mmx l56mmx20C^m is taken as an example.
And the polycrystalline cell has three main grid lines, and four segments of back electrode, a size of each segment of the back electrode is 24.5mmx3mm. The basis material of the conductive strip used in this embodiment is a tin-coated copper strip with a size of 0.2mm (thickness) x2.5mm
(width), in which the copper is 0.18 mm, and the tin-coated layer is 0.2 mm.
Firstly, a rolled tin-coated copper strip is disposed into an automatic series welding machine with a pressing mold, then solar cells are disposed in the automatic series welding machine, so that the solar cells are welded in series with the tin-coated copper strip which has been processed by a pressing treatment, so as to obtain the cell strings. After the pressing treatment, the tin-coated copper strip had three arc sections with a total arc length of 31mm and a total chord length of
30.2mm.
The cell string was disposed on the EVA (Ethylene Vinyl Acetate ) of the glass plate, then spaces between the cell strings are set with high temperature adhesive tapes, and the cell strings are connected with each other by bus bars, then the connected cell strings are covered with EVA and TPE plates. The redundant EVA and TPE plate of the laminated product may be cut off, a frame is assembled, a junction box is connected, and finally a solar battery assembly is obtained after curing and cleaning.
A rolled tin-coated copper strip is disposed into an automatic series welding machine with a pressing mould, then solar cells are disposed in the automatic series welding machine, so that the solar cells are welded in series with the tin-coated copper strip which has been processed by a pressing treatment, so as to obtain the cell strings. After the pressing treatment, the tin-coated copper strip has three arc sections having a total arc length of 31mm and a total chord length of 30.2mm.
A P6-30 toughened glass is disposed on a laying table, and EVA is disposed on the toughened glass, in which a size of the EVA is slightly larger than that of the toughened glass. The cell strings are arranged above EVA according to predetermined spaces, using 3M high temperature adhesives, with the light receiving surfaces of the solar cells facing down.
The cell strings are arranged in series with a tin-coated bus bar having a size of 6mmx0.45mm. The bus bars of the leading-out terminals of the positive and negative electrodes were L-shaped. EVA and TPE cover the cell strings connected in series. A cut with a length of 95mm extends from the central position of the leading-out terminals to both sides thereof. A distance between a cut and a shorter edge of an end of the back plate is about 70mm, so that the leading-out terminals of the positive electrode and the negative electrode of the bus bar were extended out through the cut.
A photovoltaic assembly laminated product is obtained by testing crack with an EL tester, laminating, cooling the laminated product, and cutting off the redundant EVA and TPE plate of the laminated product formed by the pressing welding strip and the POP solar cell.
Secondly, the above assembly is installed into an aluminum frame, then the frame is connected with the back plate and connections between the frame and the back plate is filled with sealant uniformly. The sealant is also filled in the cuts of the TPE back plate of the leading-out terminal of the positive electrode and the negative electrode of the bus bar. The sealant is also filled in the specified position of junction box. The un-cured assembly is positioned in the curving apparatus, under a temperature of 25 °C + 2°C and a humidness of 70% ± 10%), for more than four hours. Next, the cured assembly is disposed on a cleaning device to clean a leftover adhesive and dirt, and the leading-out terminals of the positive electrode and the negative electrode of the bus bar are connected to the junction box before closing the cover of the junction box. Then the positive electrode and the negative electrode are connected to the junction box to form a final solar battery assembly Al .
EMBODIMENT 2
The battery assembly is formed by the method substantially similar to EMBODIMENT 1. The only difference is that, the number of the arc sections is three, the total arc length is 38.5mm, and the total chord length is 37.5mm. Therefore, a final solar battery assembly A2 is formed.
EMBODIMENT 3
The battery assembly is formed by the method substantially similar to EMBODIMENT 1. The only difference is that, the number of the arc sections is three, the total arc length is 33.5mm, and the total chord length is 32.5mm. Therefore, a final solar battery assembly A3 is formed.
EMBODIMENT 4
The battery assembly is formed by the method substantially similar to EMBODIMENT 1. The only difference is that, the number of the arc sections is five, the total arc length is 33.2mm, and the total chord length is 32.5mm. Therefore, a final solar battery assembly A4 is formed.
EMBODIMENT 5
The battery assembly is formed by the method substantially similar to EMBODIMENT 1. The only difference is that, the number of the arc sections is four, the total arc length is 34.5mm, and the total chord length is 33.9mm. Therefore, a final solar battery assembly A5 is formed.
EMBODIMENT 6
The battery assembly is formed by the method substantially similar to EMBODIMENT 1. The only difference is that, the number of the arc sections is two, the total arc length is 30.4mm, and the total chord length is 30mm. Therefore, a final solar battery assembly A6 is formed.
COMPARING EXAMPLE A polycrystalline POP cell with a size of 156ηιηιχ 156ηιηιχ200μηι is taken as an example, and the polycrystalline cell had three main grid lines, and four pieces of back electrode, a size of each piece was of 24.5mmx3mm. The basis material of the conductive strip used in this example is a tin-coated copper strip with a size of 0.2mm><2.5mm, in which the copper is 0.18 mm, and the tin-coated layer is 0.2 mm.
Firstly, a rolled tin-coated copper strip is disposed into an automatic series welding machine with a pressing mould, then solar cells are disposed in the automatic series welding machine, so that the solar cells are welded in series with the tin-coated copper strip which has been processed by a pressing treatment, so as to obtain the cell strings. The welding strip is connected with the cells together to form the cell string which is disposed on the EVA of the glass, then spaces between the cell strings are set with high temperature adhesive tapes, and the cell strings are connected with each other by bus bars, then the connected cell strings are covered by EVA and TPE plates. The redundant EVA and TPE plate of the laminated product may be cut off, a frame is assembled, a junction box is connected, and finally a solar battery assembly is obtained after curing and cleaning.
Therefore, a solar battery assembly CA1 is formed.
Performance Test
1. Hidden Crack Test
The solar battery assemblies according to EMBODIMENTS 1-6 and COMPARING EXAMPLE are tested under a same ambient temperature respectively, by using a solar battery assembly test apparatus with a crack tester. Results are list in Table 1.
2. Power Test
The solar battery assemblies according to EMBODIMENTS 1-6 and COMPARING EXAMPLE are tested with a solar simulator. Results are list in Table 2.
Table 1
Module Before Laminating After Laminating
Al OK OK
A2 OK OK
A3 OK OK
A4 OK OK
A5 OK OK A6 OK OK
CA1 OK One piece had cracks.
Table 2
Figure imgf000010_0001
It can be seen from the results of table 1 that, the solar assemblies according to embodiments of the present disclosure are not cracked before or after laminating, however, the solar assembly according to the COMPARING EXAMPLE is cracked after laminating.
It can be seen from the results of table 2 that, with the welding strip according to embodiment of the present invention, the solar assembly still has a good internal resistance, and a possibility of cracking can be reduced.
Although explanatory embodiments have been shown and described, it would be appreciated by those skilled in the art that the above embodiments cannot be construed to limit the present disclosure, and changes, alternatives, and modifications can be made in the embodiments without departing from spirit, principles and scope of the present disclosure.

Claims

WHAT IS CLAIMED IS:
1. A welding strip for solar battery, comprising:
a first strip segment comprising an arc section, wherein the number of the arc section is n, the difference between an arc length of the arc section and a chord length of the arc section is Δ L, 0.4 rara^n*AL^ 1.0 mm, and n is an integer.
2. The welding strip according to claim 1, wherein 0.4 mm:¾n*AL:¾0.65 mm.
3. The welding strip according to claim 1 or 2, wherein the number of the arc section n is 2 to 5.
4. The welding strip according to any one of claims 1-3, wherein a sum of the arc length of the arc sections is 30.4 mm to 38.5 mm.
5. The welding strip according to any one of claims 1-4, wherein a sum of the chord length of the arc sections is 30 mm to 37.5 mm.
6. The welding strip according to any one of claims 1-5, further comprising a second strip segment connected to an end of the first strip segment.
7. The welding strip according to claim 6, wherein the first and second strip segments are integrally formed.
8. The welding strip according to claim 6 or 7, wherein a width of the second strip segment is decreased gradually along a direction away from the first strip segment.
9. A solar battery assembly, comprising:
a plurality of solar cells; a plurality of welding strips configured to connect the plurality of solar cells with each other, wherein the welding strip is according to any one of claims 1-8.
10. The solar battery assembly according to claim 11, wherein each solar cell defines a front surface and a back surface and comprises a front electrode disposed on the front surface and a back electrode disposed on the back surface, the first strip segment of the welding strip is connected to a back electrode of a first solar cell of the plurality of the solar cells, and the second strip segment of the welding strip is connected to a front electrode of a second solar cell of the plurality of the solar cells located at a downstream of the first solar cell.
11. The solar battery assembly according to claim 11 or 12, wherein a position of the arc section is corresponding to a position of the back electrode.
PCT/CN2014/076416 2013-04-27 2014-04-28 Welding strip for solar battery and solar battery assembly WO2014173330A1 (en)

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