WO2015148155A1

WO2015148155A1 - Device and method for forming highly reliable connections in a photovoltaic components

Info

Publication number: WO2015148155A1
Application number: PCT/US2015/020371
Authority: WO
Inventors: Patrick M. KELLEHER; Ryan S. Gaston; Timothy J. BUSCARINO; Pearl M. MOODY; Robert L. Grove; Thomas L. II WOODS; Narayan Ramesh; Ryan N. POWELL
Original assignee: Dow Global Technologies Llc
Priority date: 2014-03-28
Filing date: 2015-03-13
Publication date: 2015-10-01

Abstract

A process comprising: (a) forming aligned ribbons by aligning one or more ribbons, one or more connector terminals, or both of a connector for a photovoltaic module with one or more ribbons of a bus for a photovoltaic module; (b) aligning a first electrode on a first side of the aligned ribbons; (c) aligning a second electrode on a second side of the aligned ribbons; (d) passing current between the first electrode and the second electrode through the aligned ribbons so that the aligned ribbons are Joined by a thermo-compression weld; wherein a contact surface of the first electrode has a surface area than is smaller than a surface area of a contact surface of the second electrode.

Description

DEVICE AND METHOD FOR FORMING HIGHLY RELIABLE CONNECTIONS IN A

PHOTOVOLTAIC COMPONENTS

FIELD

[0001] The present teachings provide a device and method for forming a connection between one or more ribbons of a photovoltaic component and one or more terminals of an electrical component located within the photovoltaic component.

BACKGROUND

[0002] Photovoltaic arrays, generally, are created by combining a plurality of photovoltaic components together (e.g., photovoltaic modules). Each of the plurality of photovoltaic components are electrically connected by a combination of one or more connectors so that energy can flow through the photovoltaic components and typically to an inverter to provide electricity to a desired location. Each of the photovoltaic components includes one or more connectors that allow for connection to an adjacent photovoltaic component. These connectors are joined within the photovoltaic module by forming one or more interna! joints that may be created by joining two or more wires and/or electrical conductors together so that a connector is joined within the photovoltaic module and can create a connection between two adjacent photovoiiaic modules. The two or more wires and/or electrical conductors are soft metals that are easily deformed and are good conductors of heat so that as heat is being applied the heat is rapidly diffused by the wires and or electrical conductors. This rapid diffusion of heat may lead to poor joint strength due to under heating or may lead to an application of high amounts of heat which may lead to overheating and to poor joint strength,, thus, the tolerances in creating the joints are narrow. Further, these joints during the manufacturing process are rapidly created so that multiple joints may be formed by a single tool, so that the connection process does not slow down the manufacture of photovoltaic components, or both. This rapid production of repeated joints may lead to repeatability issues from weld to weld such that joint strength may vary throughout the process. The photovoiiaic components are combined during an installation process by the connectors to form a photovoltaic array that is typically installed in an outside location so that the photovoltaic array is exposed to sunlight. This external environment subjects the photovoltaic components to a range of thermal related stresses that may result in differentia! shear, tensile, and compressive forces being placed on the connections and joints, which may cause the joints to fatigue and fail and prevent the solar array from working properly, resulting in maintenance of the solar array, replacement of one or more photovoiiaic components, or a combination thereof . Failure of one or more joints may cause the photovoltaic array to be inefficient and produce lower amounts of electricity or even require costly repairs or replacement of one or more photovoltaic components.

[00033 Examples of some devices and methods for forming connections in a solar module may be found in U.S. Patent No. 4,041 ,271; 4,390,770; 4,567,642; and 8,308,050 and European Application Publication No. EP848449A1 all of which are incorporated by reference herein for ail purposes.

[0004] It would be attractive to have a device and process that forms connections between two or more wires and/or electrical conductors that are sufficiently strong that the joints withstand repeated exposure to the thermally induced mechanical stresses that occur over the lifetime of the system, movement between two or more adjacent photovoltaic components, withstand repeated thermal expansion, repeated thermal contraction, have a life of 10 years or more or preferably 20 years or more; or a combination thereof of the photovoltaic components. It would be attractive to have a device and method that rapidly and repeatedly produces successive thermo-compressive welds. What is needed is a device and method that monitors the thermo-compression weids in real time so that each weld has substantially the same strength, and provides real time feedback of weld strength without sampling and destructive testing of welds. What is needed is a device and method that extends the life of components of a connection assembly so that the process does not need to be frequently stopped to replace components

SUMMARY OOOS] The present teachings meet one or more of the present needs by providing a device comprising: a connection assembly including (a) a plurality of supports; (b) one or more nests; (c) a first electrode including a refractory element; and Co) a second electrode including a refractory element, the second electrode extending through one of the one or more nests so that the second electrode is aligned with one or more ribbons, one or more terminals, or both that are in an overlapping relationship on the plurality of supports so that the first electrode and the second electrode join the one or more ribbons, the one or more terminals, or both together forming a thermo-compression weld, and wherein a contact surface of the refractory element of the first electrode has a surface area that is about 75 percent or less a surface area of a contact surface of the refractory element of the second electrode.

[0006] The present teachings meet one or more of the present needs by providing: a process comprising: (a) forming aligned ribbons by aligning one or more ribbons, one or more connector terminaSs, or both of a connector for a photovoltaic module wit one or more ribbons of a bus for a photovoltaic module; (b) aligning a first electrode on a first side of the aligned ribbons; (c) aligning a second electrode on a second side of the aligned ribbons; (d) passing current between the first electrode and the second electrode through the aligned ribbons so that the aligned ribbons are joined by a thermo-compression weld; wherein a contact surface of the first electrode has a surface area that is smaller than a surface area of a contact surface of the second electrode.

[0007] The teachings herein solve one or more of these problems by providing a devic and process that forms connections between two or more wires and/or electrical conductors that are sufficiently strong that the joints withstand repeated exposure to the thermally induced mechanical stresses that occur over the lifetime of the system, movement between two o more adjacent photovoltaic components, withstand repeated thermal expansion, repeated thermal contraction, have a life of 10 years or more or preferably 20 years or more; or a combination thereof of the photovoltaic components. It would be attractive to have a device and method that rapidly and repeatedly produces successive ihermo-compressive welds. The present teachings provide a device and method that rapidly produces successive thermo-compressive welds. The teachings herein provide a device and method that monitors the thermo-compression welds in real time so that each weld has substantially the same strength, and provides real time feedback of weld strength without sampling and destructive testing of welds. The teachings herein provide a device and method that extends the life of components of a connection assembly so that the process does not need to be frequently stopped to replace components

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 A illustrates a side view of an first electrode;

[00093 1 B illustrates an end view of the electrode of FIG. 1 A;

[00103 FSG- 2A Illustrates a side view of a second electrode;

[0011J FIG. 2B illustrates an end view of the second electrode of FIG, 2A;

[00123 FIG, 3 illustrates a perspective view of a connection assembly;

[0013] FIG, 3A illustrates a cross-sectional view of one connection assembly including photovoltaic module being connected;

[00 43 FIG, 3B illustrates a side view of a connection assembly forming a connection

[001 S3 FIG. 4 illustrates a top view of a bottom joi ing two ribbons;

[00163 FIG. 5 illustrates a graph of the application of current over time;

[00173 FIG. 6 illustrates a top view of a photovoltaic module;

[00183 FIG. 7 illustrates a close-up view of a connector of the photovoltaic module FIG. 6;

[00193 F!G. 8 illustrates an example of a photovoltaic array; and [0020] FIG. 9 illustrates a micrograph of an example of a Joint.

DETAILED DESCRIPTION

[0021] The explanations and illustrations presented herein are intended to acquaint others skilled in the art with the teachings, its principles, and its practical application. Those skilled in the art may adapt and apply the teachings in its numerous forms, as may be best suited to the requirements of a particular use, Accordingly, the specific embodiments of the present teachings as set forth are not intended as being exhaustive or limiting of the teachings. The scope of the teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated by reference for aii purposes. Other combinations are also possible as will be gleaned from the following claims, which are aiso hereby incorporated by reference into this written description,

[0022] The teaching herein provide an improved device and method of creating a joint for connecting to conductive mediums (e.g., conductors, wires), joining a connector, or both so that a plurality of photovoltaic components may be connected together to create an improved photovoltaic array. A plurality of photovoltaic modules and photovoltaic components are combined together to form a photovoltaic array that collects sunlight and converts the sunlight to electricity. The photovoltaic modules of the teachings herein may be used with a housing that contains all of the individual solar modules that make up a photovoltaic array. Preferably, the photovoltaic array taught herein is free of a separate structure that houses ai! of the solar modules that make up a solar array. More preferably, each individual solar module may be connected directly to a structure such as a roof and each of the individual sola modules is electrically connected together so that a solar array is formed (i.e., a building integrated photovoltaic {BSPV}),

[00233 The pluralit of photovoltaic components may be configured in any manner so thai each of the plurality of photovoltaic components may be electrically connected. The photovoltaic components may be comprised of a plurality of laminated layers and each of the layers may expand at different rates (i.e., have a different coefficient of thermal expansion (CTE)). One of the layers of the photovoltaic components may be electrical circuitry and the electrical circuitry may be stressed or strained during this thermal expansion. Each of the individual photovoltaic components may be electrically connected to an adjacent photovoltaic component such as a photovoltaic module by electrical circuitry. The electrical circuitry may be a ribbon, a positive bus bar, a negative bus bar, a connector, an integrated flashing piece, or a combination thereof. The ribbons may have a width that is larger than the cross-sectional width of the smaiier electrode, smaiier refractory element, or both; or stated another way the entire area of the smaiier electrode, smaiier refractor element, or both may fit withi the width of the ribbons. The ribbons as discussed herein may be any wire, eiectricai conductor, or both that extends within a photovoltaic component. The ribbons may be made of any material that conducts power, electricity, or both. The ribbons may include copper, silver, tin, indium, go!d, steei, iron, or a mixture thereof. Preferably, the ribbons are made of oxygen free copper, electrolytic tough pitched copper, or both. The ribbons may be coated with a metal that has a iower melting temperature than the base material. For example, the ribbons may be iron and coated with stiver. The bus ribbons may be coated with a materia! that prevents oxidation and/or corrosion. For example, the ribbon may be a copper ribbon that is coated with tin or indium. The bus ribbons and the connection terminal ribbons may be made of the same materia!, a different materia!, or a combination of both, A ribbon of one materia! may be connected with a ribbon of a different materia!. Preferably, the electrical circuitry are ribbons that are Joined to a connector that extends between and/or receives a connector that extends between and connects two or more adjacent photovoltaic components. More preferably, the electrical circuitry of the photovo!taic components may be one or more bus bars, one or more ribbons, or both that connects two or more photovoltaic components together. The electrical circuitry may extend from ce!i to ceil, photovoltaic module to photovoltaic module, ceil to a photovoltaic module, photovoltaic module to integrated flashing piece, or a combination thereof. For example, the joint formed b the device and teachings herein may join together a connector for each of two adjacent cel!s of a photovoltaic module so that the ceiis are eSeciricaiiy connected by a connector. In another example, a bus of a photovoltaic module and a terminal of a connector may be joined together by the teachings herein so that the connectors may be used to connect two adjacent photovoltaic components. The joint formed may join one or more connectors within an integrated flashing piece that extends between adjacent rows of photovoltaic modules and allows power to flow from one row to the adjacent row. The eiectricai circuitry may be integrated into the one or more photovoltaic cells, connect the one or mor photovoltaic ceils, be electrically connected to the one or snore photovoltaic ceiis, or a combination thereof. The eiectricai circuitry may be integrated into and/or around one or more layers of the solar module such as a reinforcement so that the eiectricai circuitry extends within the photovoltaic component. Preferably, the electrical circuitry extends through the photovoltaic component and more preferably extends through a photovoltaic moduie.

[0024] The photovoltaic moduie may function to capture energy from sunlight and translate the energy to inverter to create electricity. The photovoltaic module may include one or more cells that function to capture energy from sunlight. The one or more ceiis may be joined (e.g., electrically, mechanically, or both), may be joined to one or more bus bars, or both. The one or more ceils may be made of any material that functions to capture energy from sunlight that can be converted into electricity. The one or more cells may be connected by one or more ribbons, to one or more bus bars, or both. The one or more ribbons, one or more bus bars, or both may connect cell to ceil may run the length and/or width of the photovoltaic module, or both. Preferably, as discussed herein the bus bars are a larger ribbon that runs the length of the photovoltaic module and the ribbons of the cells connect to the bus bars so that the bus bars can transfer energy from photovoltaic component to photovoltaic component and ultimately to the inverter. The bus bars or bus ribbons as discussed herein may function to collect energy from the cells of the photovoltaic module and transmit the energy from one photovoltaic component to one or more photovoltaic components. The bus bars may terminate at a connector that functions to connect one photovoitaic component to an adjacent photovoitaic component.

[0025] The connector may function to form an electrical connection, a physical connection, or both between one or more adjacent components. The connector may function to receive an adjacent connector, to extend into an adjacent connector, receive a connection device, or a combination thereof. The connector may include one or more connector terminals that extend into, are incorporated into, or both a photovoltaic component so that the connector may be electrically connected, mechanically connected, or both within the photovoltaic component such as a photovoltaic module, integrated flashing piece, or both. The connector may be a male connector, a female connector, or both. The connector may include one or more connector terminals that extend therefrom for incorporating the connector into the photovoltaic component. The one or more connector terminals may extend from the connector and each form a joint with the one o more ribbons of the photovoitaic component. The one or more connector terminals may be joined with the one or more ribbons so thai a joint of sufficient strength is created to retain the connector within the photovoitaic component when a force is applied to the connector. Preferably, the one or more connector terminals are joined to the one or more ribbons by a thermo-compression weld using the device and method taught herein. Preferably, the connector is joined to one or more ribbons that form the bus bars of the photovoltaic component via one or more thermo-compression welds.

[00263 The thermo-compression welds, buttons, joints, or a combination thereof may function to electrically join, mechanically join, or both a connector to a ribbon; a ribbon to a ribbon, a terminal to a ribbon; a ribbon to a bus;, a bus to a bus; or a combination thereof. A thermo-compression weld as discussed herein once formed may be referred to as a button or a joint. The one or more buttons may have sufficient strength so that the ribbon and connector terminal cannot be pulled apart, sheared apart, or both without destroying the ribbon, ^'the connector terminal, or both. The one or more buttons joining two or more connectors together may have any of the characteristics discussed herein. Preferably, the one or more buttons at least electrically connect the one or more ribbons and the one or more connector terminals so that a connector allows for power to fiow from one photovoltaic component to another photovoltaic component. The one or more buttons may physically join two or more ribbons together so that at least a portion of the two or more ribbons form a solid state bond {i.e., there may be some diffusion at the atomic level but there is limited to no mixing in the Joint). The one or more buttons may have a sufficient amount of strength so that the one or more buttons are as strong as the base materia! of the ribbons, the connector terminals, or both, so that the buttons will not shear without destruction of ribbons, the connector, or both. The one or more buttons may have a sufficient amount of strength so that the one or more buttons are as strong as the weaker of the two base materials being joined. For example, if a copper bus and a brass bus are joined the button wilt have strength that is equal to the strength of the copper bus (i.e., the weaker base material). The one or more buttons may sufficiently intermix the two or more components being joined together so that the resulting composition of the button is a combination of the two or more components being joined together, so that the composition of the materials is different within the one or more buttons, or both. The buttons may have an area larger than the area of the smallest electrode. The area of the buttons may be substantially the same size as the smallest electrode, Preferably, the buttons may be smalle than the area of the smallest electrode (e.g., the first refractor element). The one or more buttons may be formed by one or more refractory elements of the one or more electrodes contacting the two or more ribbons and compressing the ribbons, passing current through the ribbons, or both.

[0027] The electrodes may function to create one or more buttons, pass current through two or more ribbons, compress two or more ribbons, or both. The electrodes may be movable along their axis towards and away from ribbons to generate one or more buttons. Th electrodes, the refractory elements, or both may be made of a conductive material, a resistive material, a metal a metal with a lower conductivity (i.e., higher resistivity) than the materials being joined, a material with a higher conductivity than the materials being joined, or a combination thereof. Preferably, at least a tip of the electrodes (i.e., a refractory element) are made of a material with a higher resistivity than a body of the electrodes so that the tip of the refractory elements heat up and assist in transforming the ribbon (e.g., soften or form a solid state bond), transform the ribbons, or both. Ail or a portion of the electrodes may be made of copper, iron, steel, tungsten, molybdenum, magnesium, or mixtures thereof. Preferably, the contact surface (i.e., refractory element) of the electrodes are made of tungste or molybdenum. More preferably, a refractory element made of tungsten or molybdenum is connected to a tin body, a copper body, or a mixture thereof so that the electrodes are formed (i.e., the electrode is made of two or more dissimilar materials). For example, a copper body may act as a holder for holding a molybdenum refractory element such that heat produced in the electrode tip is quickly conducted away from the copper body and into a cooling structure such as a water jacket. One or more or preferably two electrodes may be used to create each button. The electrodes may be identical Preferably, th electrodes are different based upon their position within the connection assembly. The connection assembly may include a first electrode and a second electrode, The electrodes may be vertically oriented, horizontally oriented, oriented along a common axis, or a combination thereof. Preferably, the first electrode and second electrode travel along substantially the same axis so that the two or more ribbons are sandwiched between the electrodes during creation of a button. The electrodes may be substantially aligned so that a contact surface (e.g., refractory element tip) of the first electrode and a contact surface {e.g., refractory element tip) of the second electrode substantially overlap, are both substantially covered, at least one contact surface is entirely located within a contact surface of the opposing electrode, or a combination thereof.

[0028] The first electrode and the second electrode may be identical. Preferably, the first electrode and the second electrode are different, made of different materials, have a different structure, have a different contact surface area, or a combination thereof. The first electrode may have a smaller contact surface area than a contact surface area of the second electrode or vice versa. Preferably, the contact surface of the first electrode fits entirely within the contact surface of the second electrode. The area of contact surface of the second electrode and preferably the second refractory element may be about 1.1 times or more, about 1.2 times or more, about 1.3 times, or even about 1 .5 times or more the area of the first electrode and preferably the second refractory element or vice versa. The area of contact surface (e.g., refractory element) of the second electrode may be about 5 times or less, about 3 times or less, or about 2 times or less the area of the first electrode, or vice versa. Stated anothe way the first electrode, first refractory element, or both may have a contact surface with an area that is about 90 percent or less, about 75 percent or less, or even about 60 percent or less of the second electrode, second refractory element, or both, or vice versa. The contact surface of the electrodes, refractory elements, or both may have any shape so that the contact surfaces function to create a thermo-compression weld. The contact surfaces may have the same shape or may have different shapes. The contact surfaces may be oval, square, circular, diamond, symmetrical, asymmetrical, or a combination thereof. Preferably, the shape of the contact surfaces are generally circular. The first electrode, the second electrode, first refractory element, second refractory eiement, or a combination thereof may include one or more chamfers, one or more steps, or both. The one or more chamfers, one or more steps, or both may form a shoulder that reduces the size of the contact area, the refractory element, or both, that extends from a body (e.g., main) portion of the electrode, The one or more chamfers may extend at an ang!e sloping towards the contact surface. The angle of the chamfers may be sufficiently large so that the chamfer functions to maintain the contact surface, the body, the refractory elements, or a combination thereof free of splatter, contaminants, or both. The chamfer may taper the electrodes, the refractory elements, or both as an upper portion of th electrode extends towards a contact surface. The one or more electrodes may be located within a connection assembly, an electrode holder, in communication with a cooling structure, or both.

[0029] The cooling structure may function to cool the first electrode, the second electrode, a body of the electrodes, a refractory element (i.e., tip) of the electrodes, or a combination thereof. The cooling structure may function to maintain the eiectrodes at a constant temperature. The cooling structure may contact all or a portion of the body, the tip, or both of the first electrode, the second electrode, or both. The cooling structure may be wafer, air, a liquid, a fluid, a refrigerant, a recirculation loop, a fresh supply of a cooling fluid, or a combination thereof. The cooling structure may be a water jacket that receives a portion of the electrodes between formation of each joint. The water jacket may receive a recirculated fluid, a stream of fresh fluid, or both. The cooling structure may be part of the connection assembly, an electrode holder, or both. The cooling structure may be an Integral part of the electrode hoider, the connection assembly, or both.

00301 The one or more electrode holders may function to grip one or both electrodes, electrically connect one or more both electrodes, grips one or both electrodes, positions one or both electrodes, provides a rapid disconnect for one or both electrodes, or a combination thereof. The electrode holder may provide cooling to one or both of fhe electrodes. Preferably, th electrode hoider includes an integral cooling structure as is discussed herein. The electrode hoider may include an electrical connector that conducts electricity into the electrodes so that fhe electrodes provide electricity to a position of interest. The electrode hoider may include one or more wires, conductors, or both for providing electricity into the eiectrodes. The one or more electrode holders may be movable, include a movable gripping structure, a connector, or a combination thereof to retain one or more electrodes. The one or more electrode holders may connect the one or more electrodes to a mechanical positioning system, assist in positioning the one or more electrodes relative to each other, or both. The one or more electrode holders may assist in axiaSly moving the eiectrodes, moving the electrodes in an axial direction relative to the eiectrodes, move the eiectrodes within the nest and/or connection assembly, or a combination thereof. The one o more electrode holders may have a quick connect disconnect feature so that the electrode holders, the eiectrodes, or both may be rapidly connected/disconnected from the connection assembly, a positioning assembly, or both. [0031] The connection assembly may function to align two or more ribbons, two or more electrodes, or both so that th two or more ribbons may be joined together. The connection assembly may axially move one or both of the electrodes. The connection assembly may guide one or both of the electrodes along its longitudinal axis so that the electrodes contact one or both of the ribbons, each other, sandwich the electrodes, or a combination thereof. The connection assembly may provide for proper fixfuring of two or more ribbons, two or more electrodes, or both relative to each other so that they may be connected together. Proper fixturing may be lateral alignment (e.g., X direction), longitudinal alignment (e.g., Y direction), height alignment (e.g., Z direction), or a combination thereof so that two or more ribbons, electrodes, or both overlap so that a connection may be formed. The connection assembly may assist in aligning the two or more ribbons relative to each other. The connection assembly may prevent lateral movement, longitudinal movement, or both of the ribbons. The connection assembly may include a channel that the ribbons are placed in during joining. The connection assembly may be flat, contoured, include a contoured portion, or a combination thereof. The connection assembly may include one or more supports that prevent the ribbons from being bent, deformed, damaged, or a combination thereof during the joining process.

[0032] The support may function to prevent movement, damage, o both to the ribbons during the process of joining. The support may function to prevent energy from the electrodes, the refractory elements, or both from passing through the support, a location other than between the electrodes, a location other than through the overlapped ribbons, or a combination thereof to form a button. The support may allow for a ribbon to be inserted from each side of the connection assembly and may assist in overfapping the ribbons. The support may provide structure to portions of the ribbons proximate to the electrodes, the nest, or both during the process of joining. The support may be made of a material that is a good conductor of electricity, heat, or both. Preferably, the support or at least a portion of the support proximate to an application of power has insulating properties so that currents are prevented from straying, current is prevented from taking a secondary path, the support cannot be used as a ground, or a combination thereof. The support may be made of any non-conductive material and/or coated with any non-conductive material that prevents energy from transferring from one o mor of the electrodes into the support. The support may be made of a materia! that is an insulator, be coated with an insulator material, or both. The support may be insulated so that energy is prevented from damaging the one or more ribbons, the one or more components connected to the one or more ribbons, or both. The support may include one or more regions where one or more electrodes extend through. The support may include one or more nests for receiving one or more electrodes. [0033] The one or more nests may function to guide one or both of the electrodes aiong their respective longitudinal axes. The one or more nests may align the electrodes so that the electrodes move along the same axis. The one or more nests ma prevent the electrodes from misaligning. Preferably, the second electrode is located within and extends through the nest and the nest aligns the second electrode. The one or more nests may include an automated device to move one of the electrodes, a positioning assembly, or both. The positioning assembly may be a discrete part of the connection assembly and may move relative to the nest. The one or more nests, the one or more positioning assemblies, or both may move the electrodes back and forth, up and down, along an axis, alig an upper electrode with a lower electrode, or a combination thereof. The automated device may compensate for wear of one or both of the electrodes. For example, if over time a length of the tip decreases by about 0.05 mm to about 0.5 mm the automated device will compensate for the loss of the about 0.05 mm to about 0,5 mm so that constant force is generated on the aligned ribbons. The one or more nests may be substantially the same size as the electrodes. The one or more nests may allow for axial movement of the one or more electrodes so that a joint can be produced.

[0034] The connection assembly may include one or more measurement devices that function to measure one or more process variables during the welding process. The variables measured by the one or more measurement devices may be current, voltage, duration, force, alignment, ramping rate, hold duration, current versus power control, tip location versus ribbon location, cleanliness of the electrodes, temperature, or a combination thereof. The one or more measurement devices may be a single measurement device that monitors one or multiple conditions. One of the one or more measurement devices may be a linear variable differentia! transformer (LVDT). The LVDT may monitor the position of the ribbons, movement of the ribbons, overlap of the ribbons, position of the ribbons relative to each other, or a combination thereof. The one or more measurement devices may measure one or more process conditions so that weld quality may be predicted without destructive testing. For example, temperature of the electrode, alignment of the ribbons, or both may be monitored and based upon the temperature achieved during the process the strength of the button may be predicted. The temperature of the electrodes, refractory elements, ribbons, terminals, or a combination thereof may be measured and/or monitored by one or more thermocouples and preferably a thermocouple in the nest, the electrode ho!der, or both. The measurement device may measure a condition and then repeat after each button is created.

[0035] The connection assembly may be used in a process to form joints, thermo- compression weld, buttons, or a combination thereof. The process may Include one or more steps and the steps as recited herein may not be listed in order and the order of the steps may be performed in a different order than are recited herein. The ribbons may be aligned so that the edges of the ribbon are substantially in Sine and the connection terminal ribbon overlaps the bus ribbon. The ribbons may be sequentially moved into alignment or simultaneously moved into alignment so that the electrodes may contact the aligned ribbons.

[0036] The first electrode may be axially moved, static, or both and the second electrode may be axially moved, static, or both so that the aligned ribbons are sandwiched between the electrodes. The electrodes may apply a force to the aligned ribbons. The electrodes may compress the two or more ribbons into contact. The force may be sufficiently large to hold the aligned ribbons in alignment, to transfer heat to the ribbons, to create an electrical connection, to join the aligned ribbons together when one or both of the aligned ribbons are softened, to compress one or both of the aligned ribbons so that a button is formed, to compress the two or more ribbons into contact, or a combination thereof. The force may be sufficiently small so that one or both of the electrodes do not punch through (i.e., coin) one or both ribbons, bend the aligned ribbons, deform the aligned ribbons, or a combination thereof. The cumulative forc of the electrodes on the aligned ribbons may be 45 N or more, SO N or more, 1400 W or more, 175 N or more, or even 225 N or more. The cumulative force of the electrodes on the aligned ribbons may be about 1000 N or less, about 850 N or less, preferabiy about 350 N or less, or more preferabiy about 2500 N or less. The cumulative amount of force applied by the electrodes may be from about 130 N to 320 N, preferably about 140 N to 270 N, and more preferably about 200 N to 245 N. The amount of force applied may be related to the amount of current applied. The amount of force may be inversely proportion to the amount of current applied.

[0037] The current may function to heat one or both refractory tips, aligned ribbons, or both. The current may function to soften on or both ribbons. The current may function to melt low melting point metals, components, materials, or a combination thereof so that the low melting point metals, components, materials, or a combination thereof may be dispelled from the joint, squeezed from the joint, flow out of the joint, or a combination thereof. The current may be ramped up so that low melting point metals, components, materials, or a combination thereof may be dispelled from surfaces of the ribbons, buses, terminals, or a combination thereof so that metal to metal solid state joints are formed. The amount of current (and force) applied may vary depending on the amount of force (or current) applied, type of material, thickness of material, type of electrodes, area of the contact surface of the electrodes, duration to create a thermo-compression weld, size of button desired, or a combination thereof. The current may be sufficiently large to heat the aligned ribbons to a predetermined temperature of about 50 percent or more, preferably about 70 percent or more, or more preferably about 80 percent or more of the melting temperature of the material of the ribbons. The amount of current provided ma heat the aligned ribbons to a predetermined temperature of about 100 percent or less, preferabiy about 95 percent or less, more preferably about 90 percent or less, or even more preferably about 85 percent or less the melting temperature of t e material of the aligned ribbons. Preferably, the predetermined temperature is less than the melting temperature of the materiai of ribbons. The amount of current supplied may be sufficiently large to soften the ribbons but not so large that any portion of the ribbons is melted. The amount of current supplied may be about 3 kA or more, about 5 HA or more, or even about 7 kA or more. The amount of current supplied may be about 50 kA or less, about 30 kA or less, about 20 kA or less, or about 10 kA or less. The amount of current supplied may vary over time. For example, once the electrodes contact the aligned ribbons current is applied and the amount of current is gradually increased over time so that the aligned ribbons begin to heat and once a predetermined current is achieved the current is held constant until a button is produced, A constant amount of current may be applied until a predetermined temperature of the aligned ribbons is achieved, a predetermined pressure is achieved, or both. The amount of current ma be gradually increased between a starting current and a welding current over about 0,001 milliseconds or more, about 0.05 milliseconds or more, about 1 milliseconds or more, or about 2 milliseconds or more. The amount of current may be gradually increased between a starting current and a welding current over about 100 milliseconds or less, about 50 milliseconds or less, or about 10 milliseconds or less. The total amount of time current may be applied is between about 1 millisecond and 100 milliseconds, preferably about 3 milliseconds and 50 milliseconds, and more preferably about 5 milliseconds and 30 milliseconds. The amount of current supplied may be a constant amount for the entire duration that current is applied. After the electrodes contact the aligned ribbons there may be a deiay in time before current is passed between the electrodes.

[0038] The delay in time may be sufficiently long so that heat is transferred from: the electrodes to the aligned ribbons. The delay in time may be sufficientl long so that the aligned ribbons raise in temperature by about 10 "C or more, about 20 ^*C or more, about 30 °C or more, or even about 50 °C or more. The delay in time before current is applied may be about 10 second or less, preferably about 5 seconds or less, or more preferably about 3 seconds or less. The delay in time may be about 0.001 second or more, about 0.01 second or more, or about 0.1 seconds or more before current is passed between the electrodes. The duration of the delay may depend upon the temperature of the electrodes before current is passed between the electrodes. For example, if the electrode is hotter (e.g., 200 °C) the deiay will be shorter {e.g., 1 second versus 3 seconds) than a delay with a cooler (e.g., 150 °C) electrode. The amount of delay ma vary depending on the materiai of the ribbons, thickness of the ribbons, size of the contact area, amount of force appiied, temperature of the electrodes, size of button desired, or a combination thereof. The dela in time may allow for one or more components of the system to stabilize, re-expand, stop moving, or a combination thereof. For example, when the two ribbons are compressed between the first electrode and the second electrode, the ribbons may expand after an initial compression so that the electrodes are pushed apart. The delay may be sufficiently long so that the expansion is stabilized before power is applied. The delay may be sufficiently long to accommodate for hysteresis of the ribbons, terminals, busses, connector tabs, or a combination thereof. All or a portion of the electrodes may be cooled to a standard temperature before the electrodes are moved into contact with the aligned ribbons.

[0030] The electrodes may be cooled to a standard temperature. The electrodes may be cooled by a fluid, by contacting the refractory elements and/or electrodes with a cooled portion of the connection assembly, the electrode hoider, or both. The electrodes may be cooled by forced convection, conductive cooling through a body of the electrode and/or an electrode holder jacket, a cooled jacket, or a combination thereof. The step of cooling may cool one or both of the electrodes. The electrodes may be cooled to the same temperature or different temperatures. During the step of cooling the electrodes may be cleaned.

[00403 The step of cleaning ma function to remove ribbon materials from the electrodes. The step of cleaning may be performed independently and/or simultaneously with another step. The step of cleaning may be performed using chemicals, abrasive materials, free of chemicals, periodically, when a condition is sensed, when a measurement raises above and/or lowers below a predetermined level, or a combination thereof.

[00413 The process as discussed herei may include one or more of the following steps performed in virtually any order. The process may include a step of aligning a first ribbon within the connection assembly, aligning a second ribbon within the connection assembly, or both. The first ribbon and second ribbon may be aligned relative to each other. A first electrode may be moved into contact with the aligned ribbons. The first electrode may be the electrode located on a bottom side of the aligned ribbons. The second electrode may be moved into a position opposite the first electrode. The second electrode may be the electrode located on a top side of the aiigned ribbons. The aligned ribbons may be compressed between the electrodes. Th electrodes may be held in position after an initial compression is created, before current is applied, or both. The hold may be for a sufficient amount of time for the aiigned ribbons, the electrodes, or both to stabilize, relax, stop springing, or a combination thereof. The hold may be for about 5 milliseconds or more but less than 15 milliseconds. Current may be applied between the electrodes, through the aligned ribbons, or both. The amount of current may be ramped up, gradually increased, or both for a sufficient amount of time that low temperature melting materials are melted and move out from between the aligned ribbons. The ramp time may be about 1 millisecond or more, 3 milliseconds or more. 5 milliseconds or more, or 20 milliseconds or less. The compression, the current, or both may be applied for a sufficient amount of time that a thermo-compression weld is formed, about 80 percent of the melting temperature of the materials is achieved, or both. Stopping current flowing between the two electrodes. Maintaining compression after current is stopped for a sufficient amount of time so that the joint solidifies.

[0042] Figure 1A illustrates a plan view of a first electrode 20 used to form thermo- compression welds and join two ribbons or a ribbon and a connector terminal together. The first refractory 20 element includes a refractory element 40 with a chamfer 24. The chamfer 24 as illustrated reduces the area of a contact surface of the first electrode 20

[0043] Figure 1 B illustrates the refractory element 40 of the first electrode 20 when viewed from an end of the first electrode 20. As illustrated the first electrode 20 includes a length (L) and a chamfer 24 thai reduces the size of the tip forming a contact surface 26 with a length (V) that is less than the length (L) so that accumulation of metal on sides of the first electrode 20 is prevented.

[0044] Figure 2A illustrates a plan view of a second electrode 22 having a refractory element 42 with contact surface 26 that is substantially the same size as a body of the second electrode 22.

00451 Figure 2B illustrates the refractory element 42 of the second electrode 22 when viewed from an end of the second electrode 22. The tip of the second electrode 22 includes a contact surface 26 having a length (L).

[00463 Figure 3 illustrates a perspective view of a connection assembly 28. The connection assembly 28 Includes two opposing nests 32. Each of the nests 32 include two opposing electrode holders 70 and one electrode holder holds a first electrode 40 and one electrode holder 70 holds a second electrode 42. A nozzle 26 is positioned proximate to a contact point between the first electrode 40 and the second electrode 42 so that an inert gas. a cooling fluid, or both can be supplied to the point of contact. As illustrated, a photovoltaic module 10 is resting on a support 30 so that connections can be formed within the photovoltaic module 10.

00473 Figure 3A illustrates a view along lines 3A-3A with the support removed so that the components of the nest 32 are exposed. The next 32 includes an upper electrode holder 70 that houses a first electrode 20 and a lower electrode holder 70 that houses a second electrode 22. The upper electrode holder 70 and the lower electrode holder 70 align the first electrode 20 and the second electrode 22 across from each other so that they substantially align. A plurality of supports 30 support the photovoltaic module and especially the ribbons 8 of the cells and the buss ribbons 12 so that the ribbons 8 and the buss ribbons 12 can be connected together by the first electrode 20 and the second electrode 22.

[0048J Figure 3B illustrates a side view of a connection assembly 28 including a bus ribbon 12 and a connector terminal 14 being joined together. As shown a bus ribbon 12 extends over a connector terminal 14. The bus ribbon 12 and connector terminal 14 are overiapped between the first electrode 20 and the second electrode 22 so that the first electrode 20 and the second electrode 22 are brought into contact with the bus ribbon 12 and the connector terminal 14 to create a button {i.e. a thermo-compression weid) (not shown). When the first electrode 20 and the second electrode 22 are brought into contact, current is passed through the bus ribbon 12 and the connector terminal 14 to assist in creating the button (not shown). The second electrode 22 extends through a nest 32 in a support 30 so that the first electrode 20 and the second electrode 22 align each time a button (i.e., a thermo-eompression weld) is formed. The connection assembly 28 includes a measurement device 50 that monitors one or more process conditions of the connection assembly 28. The first electrode 20 includes a cooling structure 80 that contacts a portio of the first electrode 20 so that the temperature of the first electrode 20 is controlled, and the second electrode 22 is in communication with an eiectrode holder 70 that assists in moving the second electrode 22 through the nesi 32.

[00493 Figure 4 illustrates an example of a button 6 that joins a bus ribbon 12 and a connector terminal 14,

[00S03 Figure 5 illustrates an application of current over time during the creation of a button. Initially the level of current is gradually increased for a time (U) heating the first electrode and the second electrode. Once a predetermined heat is achieved a constant current is applied for a time (W) so that a button is created.

[0051 J Figure 6 illustrates a photovoltaic module 10 with the electrical circuitry exposed. As illustrated, the individual: cells 16 of the photovoltaic module 10 are shown. A pair of bus ribbons 12 extend above the ceils 18 and connect to connector terminals 14 of a connector 6. The connectors 6 are configured to connect the photovoltaic module 10 to an another photovoltaic component (not shown).

100523 Figure 7 illustrates a close-up view of the connector 6 of Figure 6. The connector 6 includes a pair of connector terminals 14 that extend from the connector 6, Each of the connector terminals 14 are connected to a bus ribbon 12 of the photovoltaic module by a thermo-compression weld forming a button 16 that joins each bus ribbon 12 to a connector terminal 14.

[0053| Figure 8 illustrates an example of a photovoltaic array 2. The photovoltaic array 2 includes a plurality of rows of photovoltaic modules 16 connected togethe via the connectors 8 {not shown). Each row of photovoltaic modules 16 includes an integrated flashing piece 4 at the ends that connect each row together.

[00543 Figure 9 illustrates a micrograph of a button 16. The button 16 includes a bus ribbon 12 and a connector tab 14 forming a solid state joint 10. During formation of th solid state joint 110 elements are squeezed 106 so that the elements move towards the edge of the button 16 and pores 100 are formed proximate to the squeezed elements 108. The electrodes (not shown) form an indent 108 on the connector fab 14 and the bus ribbon 12.

[00553 Any numerical values recited herein include all values from the lower value to the upper value in increments of one unit provided that there is a separation of at least 2 units between any lower value and any higher value. As an example, if if is stated that the amount of a component or a value of a process variable such as, for example, temperature, pressure, time and the like is, for example, from 1 to 90, preferably from 20 to 80, more preferably from 30 to 70, it is intended that values such as 15 to 85, 22 to 88, 43 to 51 , 30 to 32 etc, are expressly enumerated in this specification. For values which are !ess than one. one unit is considered to be 0.0001 , 0.001 , 0,01 or 0.1 as appropriate. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in ibis application in a similar manner.

[0056] Unless otherwise stated, all ranges include both endpoints and all numbers between the endpoints. The use of "about" or "approximately" in connection with a range appiies to both ends of the range. Thus, "about 20 to 30" is intended to cover "about 20 to about 30", inclusive of at least the specified endpoints.

[0057] The disclosures of ail articles and references, including patent applications and publications, are incorporated by reference for all purposes. The term "consisting essentially of to describe a combination shall include the elements, ingredients, components or steps identified, and such other elements ingredients, components or steps that do not materially affect the basic and novel characteristics of the combination. The use of the terms "^"comprising" or "including" to describe combinations of elements, ingredients, components or steps herein also contemplates embodiments that consist essentially of the elements, ingredients, components or steps. By use of the term "may" herein, it is intended that any described attributes that "may" be included are optional

[0OS8J Plural elements, ingredients, components or steps can be provided by a single integrated element, ingredient, component or step. Alternatively, a single Integrated element, ingredient, component or step might be divided into separate plural elements, ingredients, components or steps. The disclosure of "a" or "one" to describe an element, ingredient, component or step is not intended to foreclose additional elements, ingredients, components or steps.

[QOS0] It is understood that the above description is intended to be illustrative and not restrictive. Many embodiments as well as many applications besides the examples provided will be apparent to those of skill in the art upon reading the above description. The scope of the teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled The disclosures of all articles and references, including patent applications and pubiications, are incorporated by reference for ail purposes. The omission in the following claims of any aspect of subject matter that is disclosed herein is not a disclaimer of such subject matter nor should it be regarded that the inventors did not consider such subject matter to be part of the disclosed inventive subject matter.

Claims

We claim:

1 ) A process comprising;

a, forming aligned ribbons by aligning one or more ribbons, one or more connector terminals, or both of a connector for a photovoltaic module with one or more ribbons of a bus for a photovoltaic module;

b. aligning a first electrode on a first side of the aligned ribbons;

c, aligning a second electrode on a second side of the aligned ribbons; d. passing current between the first electrode and the second electrode through the aligned ribbons so that the aligned ribbons are Joined by a thermo- com press ion weld; wherein a contact surface of the first electrode has a surface area that is smaller than a surface area of a contact surface of the second electrode.

2} The process of ciaim 1 , wherein the process includes a step of cooling the first electrode, the second electrode, or both to a standard temperature before creating a subsequent thermo-compression weld,

3) The process of any of the preceding claims, wherein the process includes a step of compressing the aligned ribbons between the first electrode and the second electrode.

4} The process of a y of the preceding claims, wherein a force is a plied between the first electrode and the second electrode,

5) The process of any of the preceding claims, wherein there is a delay in time between an application for force and an application of current to create the thermo-compression weld,

6} The process of any of the preceding claims, wherein the first electrode includes a refractory element made of molybdenum, tungsten, or both, and the second electrode includes a refractory element made of molybdenum, tungsten, or both.

7} The process of any of the preceding claims, wherein the second electrode is located within a nest that aligns the first electrode with the second electrode. 8) The process of claim 7, wherein the second electrode and the first electrode are aligned so that the contact surface of the first electrode is entirely located within the contact surface of the second electrode.

9} The process of any of the preceding claims, wherein an amount of current passed through the aligned ribbons is gradually increased so that the ribbons are gradually heated as the amount of current is increased,

10) The process of claim 9, wherein once a predetermined temperature of the aligned ribbons is achieved the amount of current is held constant to form a thermo-compression button.

11 ) The process of claim 10, wherein the predetermined temperature is about 80 percent of a melting temperature of the one or more ribbons of the bus, the one or more ribbons of the connector, the one or more connector terminals, or a combination thereof.

12) The process of claim 10, wherein the predetermined temperature is less than the melting temperature of the one or more ribbons of the bus, the one or more ribbons of the connector, the one or more connector terminals, or a combination thereof.

13} The process of any of the preceding claims, wherein the contact surface of the first electrode is about 75 percent the size of the contact surface of the second electrode.

14) The process of any of the preceding claims, wherein the thermo-compression weld is formed by the current passing between the first electrode and the second electrode and the thermo-compression weld is smaller than the surface area of the first electrode,

15) The process of any of claims 5 through 1 , wherein the force is sufficiently large to hold the aligned ribbons together and assist in softening the aligned ribbons, but sufficiently small so that the aligned ribbons are not deformed by the force,

18) The process of any of the preceding claims, wherein the one or more ribbons, one or more connector terminals, or both of the connector for the photovoltaic module are laterally and longitudinally aligned with the one or more ribbons of the bus for the photovoltaic module within a connection assembly that retains the one or ribbons, one or more connector terminals, or both of the connector for the photovoltaic module and the one or more ribbons of the bus for the photovoltaic module. 17) The process of any of the preceding claims, wherein a position of the first electrode, the second electrode, or both is adjusted to compensate for wear of the first eiectrode, the second electrode, or both and so that a consistent weid force is applied to the one or more ribbons, the one or more connector terminals, or both,