Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F77/00—Constructional details of devices covered by this subclass
  • H10F77/93—Interconnections
  • H10F77/933—Interconnections for devices having potential barriers
  • H10F77/935—Interconnections for devices having potential barriers for photovoltaic devices or modules
  • H10F77/937—Busbar structures for modules
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F19/00—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules
  • H10F19/90—Structures for connecting between photovoltaic cells, e.g. interconnections or insulating spacers
  • H10F19/902—Structures for connecting between photovoltaic cells, e.g. interconnections or insulating spacers for series or parallel connection of photovoltaic cells
  • H10F19/908—Structures for connecting between photovoltaic cells, e.g. interconnections or insulating spacers for series or parallel connection of photovoltaic cells for back-contact photovoltaic cells
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F71/00—Manufacture or treatment of devices covered by this subclass
• • 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
• • 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49002—Electrical device making
  • Y10T29/49117—Conductor or circuit manufacturing

Definitions

• This invention relates to the field of photovoltaic modules and, in particular, to busbar components for photovoltaic modules.
• PV cells provide a renewable source of electrical energy.
• the electrical energy collected from all of the PV cells can be combined in series and parallel arrangement to provide power with a certain voltage and current.
• Many recent design and engineering advances have increased the efficiency and functionality of PV modules.
• a solar cell may be fabricated by forming P- type and N-type active diffusion regions in a silicon substrate. Solar radiation impinging on the solar cell creates electrons and holes that migrate to the active diffusion regions, thereby creating voltage differentials between the active diffusion regions.
• both the active diffusion regions and the metal grids coupled to them are on the back side of the solar cell. The metal grids allow an external electrical circuit to be coupled to and be powered by the solar cell.
• Back side contact solar cells are also disclosed in U.S. Pat. Nos. 5,053,083 and 4,927,770, which are both incorporated herein by reference in their entirety.
• Figure 1 illustrates the backside connections of a photovoltaic module
• Figure 2A illustrates a connection of busbar components to photovoltaic cells that are misaligned
• Figure 2B illustrates a busbar tab to cell pad connection
• Figure 3A illustrates placement of busbar components that are connected with a busbar component connection joint to accommodate for misalignment of the cells according to one embodiment of the present invention
• Figure 3B illustrates the electrical connection of a busbar tab to a cell connection pad in accordance with one embodiment of the invention
• Figure 3C illustrates busbar components according to an alternate embodiment of the present invention.
• Figures 4A and 4B illustrate exemplary per cell busbar components in accordance with one embodiment of the invention
• Figures 4C illustrates a connection member for connecting the busbar components of Figures 4A and 4B in accordance with one embodiment of the invention
• Figure 4D illustrates connection of the exemplary busbar components of Figures 4A and 4B with the connection member of Figure 4C in accordance with one embodiment of the invention
• Figure 5 illustrates a process of making a photovoltaic module in accordance with one embodiment of the invention.
• Figure 1 illustrates the back side of a PV module 4, which is not typically seen from the outside of the PV module.
• Figure 1 also illustrates that the busbar components may be located behind the PV cells (verses adjacent to the cells) to improve the aesthetic look and electrical efficiency of the PV module.
• the PV cells illustrated in Figure 1 are back contact cells.
• the PV module 4 includes an array of PV cells connected to one another by busbar components at either end of the module.
• PV module 4 includes an array of cells 604, which is illustrated as 6 x 8 array in Figure 1.
• the array of cells are arranged into strings, the strings arranged adjacent one another, for example, six strings of eight cells each are illustrated in Figure 1. It will be appreciated that the number and arrangement of the array of cells may vary from that illustrated.
• Busbar components couple the strings of cells at each end.
• busbar component 5 couples string column B (including PV cells 2 and 4) with string column A (including PV cells 1 and 3).
• Figure 2A illustrates a more detailed view of an end of module 4 having PV cells that are misaligned.
• Cells 2 and 4 represent the end cells in string column B of the PV module 4 cell array.
• Cells 1 and 3 represent the end cells in another string column A of the PV module 4 cell array.
• the electrical contacts for PV cells to a busbar component are typically solder pads.
• the tabs on a busbar component may be soldered to the cell connection pads of the PV cell to electrically connect the busbar with the cells.
• the busbar component 5 that is intended to electrically connect the two cell columns A and B is connected to the cell connection pads 7, 8 and 9 of PV cell 1 and cell connection pads 11, 12 and 13 of PV cell 2.
• the busbar component 5 is composed of a single piece body 10 having tabs (e.g., tabs 10 and 18) that are joined (e.g., by solder) to respective cell connection pads of each of PV cells 1 and 2.
• Such an illustrated busbar component may be unable to accommodate stack-tolerance- caused misalignment of cell strings with small cell connection pads.
• busbar component 5 is unable to make an electrical connection with all of the pads of each cell and/or may make electrical contact to a region of opposite polarity outside of one or more of the pads.
• cell 2 is offset by a rotation angle of A degrees and distance X from cell 1 creating a misalignment of the busbar component tabs with the pads of cell 2.
• busbar connection tab 16 does not make contact with pad 16 of cell 902 at all, and bus tab 10 makes minimal contact with pad 12 of cell 2.
• An electrical connection between the busbar and the cell outside of the solder pad area can cause electrical shorting or shunting of the cell, resulting in rework and/or yield loss.
• the cell connection pad may, therefore, be sized larger to prevent this deleterious electrical connection. Because the busbars are configured to connect to a plurality of cells, the cell connection pads must be large (e.g., 8mm x 8mm) to compensate for misalignment among the cells. However, large cell connection pads result in cell inefficiency due to voltage- dependent collection in the pad area. In addition, if the misalignment is significant, short outs often result because the busbar tabs make contact with a region of the opposite polarity to the connection pad.
• the cell connection pad 20 size is also a function of the width 25 of busbar tab 22, the distance 27 of solder 24 flow from the busbar tab 22 and the other misalignment among the bus connection elements (e.g., solder paste, insulator 26 and heating elements), as illustrated in Figure 2B.
• the distance provided for misalignment is typically at least four times the standard deviation of the misalignment, the standard deviation of the misalignment in any direction being the square root of the sum of the squares other contributions, assuming each contribution to misalignment is independent and normally distributed.
• the purpose of insulator 26 is to prevent electrical contact of the busbar to regions of the cell with opposite polarity from the connection pads. As described in co-pending patent application serial no.
• the insulator may be part of the cell, a separate piece, or part of the busbar.
• Embodiments of the present invention overcome the above noted problems by adding at least one busbar connection joint to a busbar assembly to accommodate for misalignment between cells in a PV array.
• Busbar components are connectable to one another with a connection point or via a separate busbar connection member (having multiple connection joints) to form a busbar assembly.
• pre-assembled busbar components are configured to be aligned and connected to individual cells.
• the pre-assembled busbar components may be unitarily formed pieces or, alternatively, may be pre-formed by, for example, soldering or welding tabs to the body of the busbar component. Adjacent pre-assembled busbar components can then be connected to one another. Because the pre-assembled busbar components are connected together with at least one busbar connection joint, the coupled string of pre- assembled busbar components can compensate for misalignment by, for example, allowing off linear axis alignment of the busbar components relative to one another about the connection joint.
• connection joints are sources of potential physical failure of the busbar.
• the thickness of these joints also creates stress on the corresponding PV cells, which can break and become useless.
• the joints can add extra stress on the PV cells during module manufacturing, and the PV cells can crack, which degrades cell performance.
• breakage is frequently at the edges of PV cells because the linear configuration of busbars results in a portion of the busbar extending beyond the edge of the typically cropped corners of the PV cells.
• the use of extra connection joints adds steps to the manufacturing process which adds to manufacturing time and costs.
• Figure 3A illustrates placement of pre-assembled busbar components that are connected with a busbar connection joint to accommodate for misalignment of the cells, according to one embodiment of the present invention.
• the busbar connection joint 924 connecting the busbar components 920, 922 can act as a pivot point during alignment to accommodate for the misalignment (as shown by distance X and rotation A) of the cells 900, 902.
• FIG. 3B illustrates electrical connection of the busbar tab 950 to the cell pad 954, according to one embodiment of the present invention.
• the insulator 956 is provided between the busbar tab 950 and the PV cell.
• the purpose of insulator 956 is to prevent electrical contact of the busbar to regions of the cell with opposite polarity from the connection pads.
• the insulator may be part of the cell, a separate piece, or part of the busbar.
• solder 958 When the bus tab 950 is connected to the cell pad 954, for example by soldering, solder 958 often flows beyond the bus tab 950 and onto the cell pad 954 a distance 927 to make an effective connection.
• the cell pad 954 can be minimized, compared to the previous description relative to Figure 2B and is sized to take into account the busbar tab size (e.g., width 955), the distance 927 of solder flow from the busbar tab 950 and the possible misalignment resulting from the busbar placement tolerance (caused by an imperfection in placement) and the busbar tab tolerance (caused by imperfection in busbar manufacture).
• the pre-assembled busbar components 920 and 922 may be unitary busbar components such that the busbar tabs are unitarily formed with the busbar body, as illustrated in Figure 3A.
• the busbar components 920 and 922 may be pre-formed busbar components such that the busbar tabs 941-946 are joined (e.g., by soldering) to their respective busbar elongated bodies 920 or 922 at joints 931-936 prior to alignment of the busbar tabs with the cell pads, as illustrated in Figure 3C.
• the busbar connection joint 924 need not be at a location commensurate with a busbar tab joint as illustrated in the figure but may also be disposed at another location along the busbar component 920 body.
• Three tabs are shown with each of the busbar components in
• FIGS 4 A and 4B illustrate a first busbar component 100 and second busbar component 120, respectively, in accordance with an alternative embodiment of the invention.
• Each busbar component 100, 120 is configured to connect to a photovoltaic (PV) cell of a photovoltaic (PV) module.
• PV photovoltaic
• Each of the first busbar component 100 and second busbar components 120 includes an elongate body 104, first tab 106, second tab 108, and third tab 110.
• the tabs 106, 108, 110 are used to electrically connect the busbar components 100, 120 to respective ones of PV cells.
• the elongate body 104 is used to electrically connect the tabs 106, 108, 110 (and PV cells) to a junction box of the PV module.
• the elongate body 104 is an interconnect bus and the tabs 106, 108, 110 are bus tabs.
• the elongate body 104 and tabs 106, 108, 110 of the busbar component are formed as a unitary piece.
• the busbar components 100, 120 may be formed by stamping a sheet of conductive material. It will be appreciated that the elongate body 103 and tabs 106, 108, 100 can also be formed as separate pieces that are joined together.
• the described embodiments of the invention may reduce the solder pad size of the photovoltaic (PV) cells.
• PV photovoltaic
• the cell connection pad size that only takes into account the busbar tab size (e.g., width 955), the distance 927 of solder flow from the busbar tab 950 and the possible misalignment resulting from the busbar placement tolerance (caused by an imperfection in placement) and the busbar tab tolerance (caused by imperfection in busbar manufacture). This reduced the misalignment distance from about 2.5mm on each side to about 1.5mm on each side.
• the cell connection pad size (e.g., width 928 and length 929) can be reduced from to about 7mm x 6mm or smaller with the same level of yield loss and rework. It should be noted that alternative embodiments may utilize other shapes, dimensions and sizes for the various elements described herein. [0033] As noted above, it will also be appreciated that one of skill in the art would expect these advantages from using fewer connection joints, as opposed to additional connection joints. Simple analysis of pads in back contact solar cells indicates that the areas under the pads are active on at least one polarity. However, numerical analysis shows that the area under the pads is subject to voltage-dependent collection.
• the elongate body 104 or the tabs 106, 108, may be provided. It will be appreciated that fewer than three or greater than three tabs may be provided. It will be appreciated that the number of tabs provided on the busbar component 100, 120 depends on the electrical contact requirement of each cell to which the busbar component is to be connected. [0035] In one embodiment, the elongate body 104 or the tabs 106, 108,
• the elongate body 104 may have a curved shape along the length of the elongate body 104.
• the elongate body 104 and the tabs 106, 108, 110 may intersect at an angle that is not rectilinear, as illustrated in Figures 4A-4B.
• one, some or all of the individual tabs 106, 108, 110 may extend away from the elongate body 104 at an angle other than 90 degrees (e.g., 60 degrees).
• a tab 110 at the end of the elongate body may be formed as a curvilinear extension of the elongate body 104, so that the elongate body 104 curves approximately 90 degrees to form the tab 110.
• the tabs 106, 108, 110 may have rounded ends and rounded interior or exterior corners where the tabs 106, 108, 110 intersect the elongate body 104.
• the elongate body 103 may be adapted to have a terminal bus (not shown) connected thereto.
• the elongate body 104 may include a unitarily formed extension (not shown), the extension being a terminal bus or a connection to a terminal bus.
• Figure 4C illustrates a busbar connection member 130 in accordance with one embodiment of the invention.
• the illustrated busbar connection member 130 includes a first busbar connection joint 132 and a second busbar connection joint 134.
• the busbar connection member 130 is configured to connect the first busbar component 100 with the second busbar component 120 at the first busbar connection joint 132 and second busbar connection joint 134, respectively.
• busbar connection member 130 may vary from that illustrated in Figure 4C.
• busbar connection member 130 is formed from the same conductive material as the busbar components 100, 120.
• Figure 4D illustrates connection of the first busbar component
• the first busbar component 100 is connected with the second busbar component 120 by coupling the busbar connection member 130 with the elongate body 104 of each of the first busbar component 100 and the second busbar component 120 at the first connection joint 132 and second connection joint 134, respectively.
• the busbar connection member 130 is connected to the first busbar component 100 and second busbar component 120 by soldering.
• Alternative joining techniques include, for example, welding, electrically conductive adhesives, mechanical fasteners, or other coupling technologies.
• FIG. 5 is a flow chart illustrating a method for forming a photovoltaic module in accordance with one embodiment of the invention.
• the method 800 begins by forming first and second pre-assembled busbar components (block 804).
• the pre-assembled busbar components may be formed by as described in the above referenced co- pending patent application.
• the method 800 continues by, optionally, optically aligning the first pre-assembled busbar component with a first cell (block 810), and optically aligning the second pre-assembled busbar component with the second cell (block 812).
• the busbar components are connected to the cell by joining the bus tabs with the electrical contacts on the cell.
• the bus tabs are soldered with the electrical contacts. It will be appreciated that alternative joining technologies may be used as described hereinabove.
• the method 800 continues by connecting the first busbar component with the second busbar component (block 816), as needed.
• the first busbar component and second busbar component are joined directly together.
• the first busbar component and second busbar component are joined together by an intermediate busbar connection member.
• the busbar components are soldered together. It will be appreciated that alternative joining technologies may be used as described hereinabove.
• the method 800 continues by connecting an array of cells together using the busbar components to form a photovoltaic module (block 820).
• a terminal bus may also connect the busbar components and array of cells with a junction box.
• the method 800 may vary from that illustrated.
• the method 800 may include fewer steps or more steps than described above.
• the order of the steps may vary from that described above.
• the method may also include, optionally, aligning first and second insulators with the first and second cells prior to positioning the busbar component.
• busbar components and/or insulators are aligned using a vision system associated with a robot used to position and couple the busbar components to the cells and one another.
• the vision system takes an image of the cell, relays the image to a programmer, which using the image, optically aligns the insulators and/or busbar components.
• the vision system may separately align the insulator and busbar using the same image.
• Another exemplary advantage of embodiments of the invention includes individual alignment of a pre-assembled busbar component to a cell, resulting in a reduction of cell short outs.

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• Photovoltaic Devices (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Coupling Device And Connection With Printed Circuit (AREA)
• Connection Of Batteries Or Terminals (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (2)

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ID=40674507

Family Applications (1)

Country Status (7)

Cited By (2)

Families Citing this family (49)

Family Cites Families (23)

• 2007
  • 2007-11-30 US US11/998,507 patent/US20090139557A1/en not_active Abandoned
• 2008
  • 2008-09-30 CN CN2008901002267U patent/CN201898137U/zh not_active Expired - Lifetime
  • 2008-09-30 JP JP2010535948A patent/JP5633930B2/ja active Active
  • 2008-09-30 KR KR1020107014430A patent/KR101513760B1/ko active Active
  • 2008-09-30 EP EP08858171.5A patent/EP2220691B1/en active Active
  • 2008-09-30 WO PCT/US2008/011333 patent/WO2009073061A2/en not_active Ceased
  • 2008-09-30 AU AU2008331938A patent/AU2008331938B2/en active Active
• 2015
  • 2015-03-11 US US14/645,250 patent/US20150249162A1/en not_active Abandoned
• 2018
  • 2018-10-08 US US16/154,583 patent/US20190044000A1/en not_active Abandoned

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