Patent Description:
Typical spaceflight-capable solar cell panel assembly involves building long strings of solar cells. These strings are variable in length and can be very long, for example, up to and greater than <NUM> cells. Assembling such long, variable, and fragile materials is difficult, which has prevented automation of the assembly.

Existing solutions use solar cells assembled into CIC (cell, interconnect and coverglass) units. The CIC has metal foil interconnects connected to the front of the cell that extend in parallel from one side of the CIC. The CICs are located close to each other and the interconnects make connection to the bottom of an adjacent cell. Using these interconnects, the CICs are assembled into linear strings. These linear strings are built-up manually and then laid out to form a large solar cell array comprised of many strings of variable length.

Additionally, a bypass diode is used to protect the cells from reverse bias, when the cells become partially shadowed. The bypass diode generally connects the back contacts of two adjacent cells within the solar cell array.

When used in a satellite, the solar cell array is typically packaged as a panel. The dimensions of the panel are dictated by the needs of the satellite, including such constraints as needed power, as well as the size and shape necessary to pack and store the satellite in a launch vehicle. Furthermore, the deployment of the panel often requires that some portions of the panel are used for the mechanical fixtures and the solar cell array must avoid these locations. In practice, the panel is generally rectangular, but its dimensions and aspect ratio vary greatly. The layout of the CICs and strings to fill this space must be highly customized for maximum power generation, which results in a solar panel fabrication process that is highly manual.

<CIT> discloses a solar generator panel and corresponding satellite.

What is needed, then, is a means for promoting automated manufacturing of solar arrays, while preserving the ability for customization of solar cell arrays.

The present application relates to a substrate for a solar cell panel, according to claim <NUM>, and to a method of repairing a substrate on which solar cells are attached, according to claim <NUM>. Optional features are further specified in the dependent claims.

In the following description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration a specific example in which the disclosure may be practiced. It is to be understood that other examples may be utilized and structural changes may be made without departing from the scope of the present disclosure.

A new approach to the design of solar cell arrays, such as those used for spaceflight power applications, is based on electrical connections among the solar cells in the array.

This new approach rearranges the components of a solar cell and the arrangements of the solar cells in the array. Instead of having solar cells connected into long linear strings and then assembled onto a substrate, the solar cells are attached individually to a substrate, such that comer regions of adjacent cells are aligned on the substrate, thereby exposing an area of the substrate. Electrical connections between cells are made by comer conductors formed on or in the substrate in these corner regions. Consequently, this approach presents a solar cell array design based on individual cells.

Thus, a single laydown process and layout can be used in the fabrication of solar cell arrays. Current flow between solar cells will be assisted with conductors embedded in the substrate. These electrical connections define the specific characteristics of the solar cell array, such as its dimensions, stayout zones, and circuit terminations. This approach simplifies manufacturing, enables automation, and reduces costs and delivery times.

<FIG> and <FIG> illustrate conventional structures for solar cell panels <NUM>, which include a substrate <NUM>, a plurality of solar cells <NUM> arranged in an array, and electrical connectors <NUM> between the solar cells <NUM>. Half size solar cells <NUM> are shown in <FIG> and full size solar cells <NUM> are shown in <FIG>. Space solar cells <NUM> are derived from a round Germanium (Ge) substrate starting material, which is later fabricated into semi-rectangular shapes to improve dense packing onto the solar cell panel <NUM>. This wafer is often diced into one or two solar cells <NUM> herein described as half size or full size solar cells <NUM>. The electrical connectors <NUM> providing electrical connections between solar cells <NUM> are made along the long parallel edge between solar cells <NUM>. These series connections (cell-to-cell) are completed off-substrate, as strings of connected solar cells <NUM> are built having lengths of any number of solar cells <NUM>. The completed strings of solar cells <NUM> are then applied and attached to the substrate <NUM>.

In <FIG>, wiring <NUM> is attached at the end of a string of solar cells <NUM> to electrically connect the string to other strings, or to terminate the resulting circuit and bring the current off of the array of solar cells <NUM>. String-to-string and circuit termination connections are typically done on the substrate <NUM>, and typically using wiring <NUM>. However, some solar cell panels <NUM> use a printed circuit board (PCB)-type material with embedded conductors.

Adjacent strings of connected solar cells <NUM> can run parallel or anti-parallel. In addition, strings of connected solar cells <NUM> can be aligned or misaligned. There are many competing influences to the solar cell <NUM> layout resulting in regions where solar cells <NUM> are parallel or anti-parallel, aligned or misaligned.

<FIG> illustrate improved devices and structures for a solar cell panel 10a, according to one example, wherein <FIG> is an enlarged view of the details in the dashed circle in <FIG>. The various components of the solar cell panel 10a are shown and described in greater detail in <FIG>.

The solar cell panel 10a includes a substrate <NUM> for solar cells <NUM> having one or more corner conductors <NUM> thereon. In one example, the substrate <NUM> is a multi-layer substrate <NUM> comprised of one or more Kapton® (polyimide) layers separating one or more patterned metal layers. The substrate <NUM> may be mounted on a large rigid panel 10a similar to conventional assembles. Alternatively, the substrate <NUM> can be mounted to a lighter more sparse frame or panel 10a for mounting or deployment.

A plurality of solar cells <NUM> are attached to the substrate <NUM> in a two-dimensional (<NUM>-D) grid of an array <NUM>. In this example, the array <NUM> is comprised of ninety-six (<NUM>) solar cells <NUM> arranged in four (<NUM>) rows by twenty-four (<NUM>) columns, but it is recognized that any number of solar cells <NUM> may be used in different implementations.

The solar cells <NUM> have cropped corners <NUM> that define corner regions <NUM>, as indicated by the dashed circle. The solar cells <NUM> are attached to the substrate <NUM>, such that comer regions <NUM> of adjacent ones of the solar cells <NUM> are aligned, thereby exposing an area <NUM> of the substrate <NUM>. The area <NUM> of the substrate <NUM> that is exposed includes one or more of the corner conductors <NUM>, and one or more electrical connections between the solar cells <NUM> and the corner conductors <NUM> are made in the corner regions <NUM> resulting from the cropped corners <NUM> of the solar cells <NUM>.

In this example, the corner conductors <NUM> are conductive paths attached to, printed on, buried in, or deposited on the substrate <NUM>, before and/or after the solar cells <NUM> are attached to the substrate <NUM>, which facilitate connections between adjacent solar cells <NUM>. The connections between the solar cells <NUM> and the corner conductors <NUM> are made after the solar cells <NUM> have been attached to the substrate <NUM>.

In one example, four adjacent solar cells <NUM> are aligned on the substrate <NUM>, such that four cropped corners <NUM>, one from each solar cell <NUM>, are brought together at the corner regions <NUM>. The solar cells <NUM> are then individually attached to the substrate <NUM>, wherein the solar cells <NUM> are placed on top of the corner conductors <NUM> to make the electrical connection between the solar cells <NUM> and the corner conductors <NUM>.

The solar cells <NUM> may be applied to the substrate <NUM> as CIC (cell, interconnect and coverglass) units. Alternatively, bare solar cells <NUM> may be assembled on the substrate <NUM>, and then interconnects applied to the solar cells <NUM>, followed by the application of a single solar cell <NUM> coverglass, multiple solar cell <NUM> coverglass, multiple cell polymer coversheet, or spray encapsulation. This assembly protects the solar cells <NUM> from damage that would limit performance.

<FIG> illustrate an alternative structure for the solar cell panel 10a, according to one example, wherein <FIG> is an enlarged view of the details in the dashed circle in <FIG>. In this example, only a few corner conductors <NUM> are printed on or integrated with the substrate <NUM>. Instead, most of the corner conductors <NUM> are contained within a power routing module (PRM) <NUM> that is attached to the substrate <NUM>.

<FIG> illustrates the front side of an exemplary solar cell <NUM> that may be used in the improved solar cell panel 10a of <FIG> and <FIG>. The solar cell <NUM>, which is a CIC unit, is a half-size solar cell <NUM>. (Full-size solar cells <NUM> could also be used.

The solar cell <NUM> is fabricated having at least one cropped corner <NUM> that defines a corner region <NUM>, as indicated by the dashed circle, such that the corner region <NUM> resulting from the cropped corner <NUM> includes at least one contact <NUM>, <NUM> for making an electrical connection to the solar cell <NUM>. In the example of <FIG>, the solar cell <NUM> has two cropped corners <NUM>, each of which has both a front contact <NUM> on the front side of the solar cell <NUM> and a back contact <NUM> on a back side of the solar cell <NUM>, where the contacts <NUM> and <NUM> extend into the corner region <NUM>. (Full-size solar cells <NUM> would have four cropped corners <NUM>, each of which would have a front contact <NUM> and a back contact <NUM>.

The cropped corners <NUM> increase utilization of the round wafer starting materials for the solar cells <NUM>. In conventional panels <NUM>, these cropped corners <NUM> would result in unused space on the panel <NUM> after the solar cells <NUM> are attached to the substrate <NUM>. The new approach described in this disclosure, however, utilizes this unused space. Specifically, metal foil interconnects, comprising the corner conductors <NUM>, front contacts <NUM> and back contacts <NUM>, are moved to the corner regions <NUM>. In contrast, existing CICs have interconnects attached to the solar cell <NUM> front side, and connect to the back side (where connections occur) during stringing.

The current generated by the solar cell <NUM> is collected on the front side of the solar cell <NUM> by a grid <NUM> of thin metal fingers <NUM> and wider metal bus bars <NUM> that are connected to both of the front contacts <NUM>. There is a balance between the addition of metal in grid <NUM>, which reduces the light entering the solar cell <NUM> and its output power, and the reduced resistance of having more metal. The bus bar <NUM> is a low resistance conductor that carries high currents and also provides redundancy should a front contact <NUM> become disconnected. Optimization generally desires a short bus bar <NUM> running directly between the front contacts <NUM>. Having the front contact <NUM> in the cropped corner <NUM> results in moving the bus bar <NUM> away from the perimeter of the solar cell <NUM>. This is achieved while simultaneously minimizing the bus bar <NUM> length and light obscuration. Additionally, the fingers <NUM> are now shorter. This reduces parasitic resistances in the grid <NUM>, because the length of the fingers <NUM> is shorter and the total current carried is less. This produces a design preference where the front contacts <NUM> and connecting bus bar <NUM> is moved to provide shorter narrow fingers <NUM>.

<FIG> illustrates the back side of the exemplary solar cell <NUM> of <FIG>. The back side of the solar cell <NUM> has a metal back layer <NUM> that is connected to both of the back contacts <NUM>.

<FIG> illustrates solar cells <NUM> arranged into the 2D grid of the array <NUM>, according to one example. The array <NUM> comprises a plurality of solar cells <NUM> attached to a substrate <NUM>, such that comer regions <NUM> of adjacent ones of the solar cells <NUM> are aligned, thereby exposing an area <NUM> of the substrate <NUM>. Electrical connections (not shown) between the solar cells <NUM> are made in the exposed area <NUM> of the substrate <NUM> using the front contacts <NUM> and back contacts <NUM> of the solar cells <NUM> and comer conductors <NUM> (not shown) formed on or in the exposed area <NUM> of the substrate <NUM>.

During assembly, the solar cells <NUM> are individually attached to the substrate <NUM>. This assembly can be done directly on a support surface, i.e., the substrate <NUM>, which can be either rigid or flexible. Alternatively, the solar cells <NUM> could be assembled into the 2D grid of the array <NUM> on a temporary support surface and then transferred to a final support surface, i.e., the substrate <NUM>.

<FIG> illustrates an example of the array <NUM> where one or more bypass diodes <NUM> are added to the exposed area <NUM> of the substrate <NUM> in the corner regions <NUM>, for use in one or more of the electrical connections. The bypass diodes <NUM> protect the solar cells <NUM> when the solar cells <NUM> become unable to generate current, which could be due to being partially shadowed, which drives the solar cells <NUM> into reverse bias. In one example, the bypass diodes <NUM> are attached to the substrate <NUM> in the corner regions <NUM> independent of the solar cells <NUM>.

<FIG> illustrates an example where the bypass diode <NUM> is applied to the back side of the solar cell <NUM>, with interconnects or contacts <NUM> for the bypass diode <NUM> connected to the back layer <NUM> and also extending into the corner region <NUM> between the front and back contacts <NUM>, <NUM>.

<FIG> illustrates a front side view of the example of <FIG>, with the interconnect or contact <NUM> for the bypass diode <NUM> (not shown) extending into the corner region <NUM> between the front and back contacts <NUM>, <NUM>.

<FIG> illustrates the solar cells <NUM> of <FIG> and <FIG> arranged into the 2D grid of the array <NUM> and applied to the substrate <NUM>, where the bypass diodes <NUM> (not shown) are applied to the back side of the solar cells <NUM>, with the contacts <NUM> for the bypass diodes <NUM> extending into the corner regions <NUM> of the solar cells <NUM>.

One advantage of this approach is that the layouts illustrated in <FIG>, <FIG> and <FIG> are generalized layouts. Specifically, these layouts can be repeated across any panel 10a dimensions desired by a customer. This greatly simplifies assembly, rework, test, and inspection processes.

The placement of the solar cell <NUM> and bypass diode <NUM> is generic. The electrical connection of the solar cells <NUM> into series connections and string terminations is important customization for the end customer and is done independent of the layout. The front contacts <NUM> and back contacts <NUM> in the corner regions <NUM> of the solar cells <NUM> must be connected. This can be done in many combinations in order to route current through a desired path.

Connections are made between the solar cells <NUM> and the corner conductors <NUM>. Front and back contacts <NUM>, <NUM> of the solar cells <NUM> are present in each corner region <NUM> for attachment to the corner conductors <NUM>. Interconnects for the front and back contacts <NUM>, <NUM> of each of the solar cells <NUM> are welded, soldered, or otherwise bonded onto the corner conductors <NUM> to provide a conductive path <NUM>, <NUM>, <NUM> for routing current out of the solar cells <NUM>.

Using the corner conductors <NUM>, any customization can be made in the electrical connections. Adjacent solar cells <NUM> can be electrically connected to flow current in up/down or left/right directions as desired by the specific design. Current flow can also be routed around stay-out zones as needed. The length or width of the solar cell array <NUM> can be set as desired. Also, the width can vary over the length of the array <NUM>.

In one example, the electrical connections are series connections that determine a flow of current through the plurality of solar cells <NUM>. This may be accomplished by the connection schemes shown in <FIG> and <FIG>, wherein <FIG> shows up/down series connections <NUM> between the solar cells <NUM> of the array <NUM>, and <FIG> shows left/right series connections <NUM> between the solar cells <NUM> of the array <NUM>. In both <FIG> and <FIG>, these series connections <NUM>, <NUM> are electrical connections between the front contacts <NUM> and back contacts <NUM> of the solar cells <NUM>, and the bypass diodes <NUM>, are made using the corner conductors <NUM> formed on or in the exposed areas <NUM> of the substrate <NUM>. These series connections <NUM>, <NUM> determine the current (power) flow, as indicated by the arrows <NUM>, through the solar cells <NUM>.

The corner conductors <NUM> between solar cells <NUM> can be in many forms. They could be accomplished using wires that have electrical connections made on both ends, which could be from soldering, welding, conducting adhesive, or other process. In addition to wires, metal foil connectors, similar to the interconnects could be applied. Metal conductive paths or traces (not shown) can also be integrated with the substrate <NUM>.

In summary, this new approach attaches the solar cells <NUM> individually to a substrate <NUM> such that the corner regions <NUM> of two, three or four adjacent solar cells <NUM> are aligned on the substrate <NUM>. The solar cells <NUM> can be laid out so that the cropped corners <NUM> are aligned and the corner regions <NUM> are adjacent, thereby exposing an area <NUM> of the substrate <NUM>. Electrical connections between solar cells <NUM> are made in these corner regions <NUM> between front contacts <NUM> and back contacts <NUM> on the solar cells <NUM>, bypass diodes <NUM>, and comer conductors <NUM> on or in the exposed area <NUM> of the substrate <NUM>, wherein these conductive paths are used to create a string of solar cells <NUM> in a series connection <NUM>, <NUM> comprising a circuit.

While the use of electrical connections between solar cells <NUM> in these corner regions <NUM> facilitates automation, there are limits to the rework and repair capabilities of this design. Solar cell arrays <NUM> go through much activity before deployment, and there are numerous chances for defects both in early manufacture and during later assembly stages, however rare. It is necessary to have a path for rework and repair to replace damaged materials.

Specifically, a rework and repair process is necessary for the 2D grid of the array <NUM>, and it is not clear how that is achieved using existing techniques. For example, the extraction and replacement of components may result in a second electrical interconnect made in the same location as a first electrical interconnect, and such a repeated connection may not have sufficient strength.

This disclosure describes a connector design that simplifies rework of these items, and facilitates repairs of the solar cell array <NUM>. Specifically, an electrical connection is repaired by removing a first interconnect in a first location in the electrical connection and by forming a second interconnect in a second location in the electrical connection different from the first location. The second location may be adjacent the first location. An area of the corner conductor used for the electrical connection is large enough to encompass both the first and second locations and preferably allows electrical current to flow around the first location.

<FIG> further illustrates a connection scheme between a plurality of solar cells <NUM>, according to one example. The connection scheme shown comprises up/down series connections <NUM> between the front contacts <NUM> and back contacts <NUM> of the solar cells <NUM>, and the bypass diodes <NUM>, made in the exposed areas <NUM> of the substrate <NUM>, using the corner conductors <NUM>. These series connections <NUM> determine the flow of current, as indicated by the arrows <NUM>, through the solar cells <NUM>.

One or more conductor elements may be added to or removed from the corner region <NUM> to select current pathways for the solar cells <NUM>. In one example, the conductor element comprises a jumper 54a, 54b that allows circuits to be terminated at the corner regions <NUM> or to direct current to the next solar cell <NUM>. The jumpers 54a, 54b bridge the electrical connections from at least one of the corner conductors <NUM> to one or more other conductive paths.

Each jumper 54a, 54b is a metal foil interconnect that is similar to existing metal interconnects used in solar cell panels <NUM>. In one example, each jumper 54a, 54b has a shape comprised of two flange elements with parallel planes connected by a web element, which enables multiple connection points. The jumper <NUM> could be welded, soldered, or joined by other methods, onto the conducting paths and connection pads. Other types of conductive elements, such as wires, as well as other shapes, could also be employed.

Specifically, <FIG> shows a jumper 54a that connects the back contact <NUM> of the top left solar cell <NUM> to the front contact <NUM> of the bottom left solar cell <NUM>. This jumper 54a also connects through the bypass diode <NUM> to the back contact <NUM> of the bottom left solar cell <NUM>. This connection path provides for the current flow <NUM> from top to bottom shown on the left side of the figure. A similar configuration using jumper 54b provides for the current flow <NUM> from bottom to top shown on the right side of the figure.

The value of this structure is significant. Now, there is a single printed corner conductor <NUM> pattern, single layout of solar cells <NUM>, and single layout of bypass diodes <NUM>. This single configuration has great advantages for automation of manufacturing, testing, and inspection. The application of a jumper 54a, 54b provides for a simple way to control the number of solar cells <NUM> in a circuit.

<FIG> shows a side view of an example wherein the substrate <NUM> is a flex sheet assembly, according to one example. The substrate <NUM> includes a polyimide base layer <NUM> with Copper (Cu) layer 56a above and Cu layer 56b below, wherein Cu layers 56a and 56b form a multilayer conductor. A conducting back sheet of polyimide <NUM> can be applied to the substrate <NUM>, which is useful in a space environment in that it will reduce the accumulation of charge. Another capability is the addition of a plated Silver (Ag) or Gold (Au) layer <NUM> on the Cu layer 56a, which improves the ability to make connections. The Cu layer 56a with plated Ag or Au layer <NUM> is patterned as the corner conductors <NUM>, and the Cu layer 56b is patterned to form buried conductors within the substrate <NUM>, including, for example, power and common lines.

Shown on the right side is the solar cell <NUM> that is attached to the substrate <NUM> with adhesive <NUM>. Also visible is the metal foil interconnect <NUM> attached to the solar cell <NUM> and the plated Ag or Au layer <NUM> of the corner conductors <NUM>. This is a rather typical construction and assembly that could form the structures presented in earlier figures.

The substrate <NUM> also includes insulating layers that separate at least one of the multilayer conductors 56a, 56b from at least another one of the multilayer conductors 56a, 56b. In one example, there are a top polyimide overlay layer 66a and bottom polyimide overlay layer 66b, wherein the top polyimide overlay layer 66a has one or more holes drilled through it, and the holes are Cu-plated vias <NUM> that electrically connect Cu layer 56a with Cu layer 56b.

Polyimide has a high breakdown strength, greater than air or vacuum, and the polyimide overlay layers 66a, 66b are useful for preventing electrostatic discharge (ESD), which is an important concern in the space environment. Furthermore, this enables corner conductors <NUM> to pass under the solar cell <NUM>. The adhesive <NUM> is non-conducting, but the continuous polyimide layer of the polyimide overlay layers 66a, 66b offers significant protection against shorting between buried conductors in Cu layers 56a, 56b and the solar cell <NUM>.

In another example, the top polyimide overlay layer 66a may be omitted underneath the solar cell <NUM>. This may be advantageous if the top polyimide overlay layer 66a is prone to bubbles or other defects.

In another example, there is an alignment between Cu layer 56a, Cu layer 56b and the top polyimide overlay layer 66a. In this example, the top polyimide overlay layer 66a almost fully encases the Cu layer 56a, polyimide layer <NUM>, and Cu layer 56b, with only small access holes to the Cu layer 56a and Cu layer 56b. This requires the top polyimide overlay layer 66a to roll up and over the corners of the Cu layers 56a and 56b. By encasing the metal of the Cu layers 56a, 56b, the top polyimide overlay layer 66a provides valuable protection against ESD.

In another example, the top polyimide overlay layer 66a has larger holes to avoid overlapping the edges of the Cu layers 56a and 56b. This top polyimide overlay layer 66a may be easier to fabricate with less defects than a full top polyimide overlay layer 66a.

In another example, there is a connection between two or more traces of the Cu layer 56a, wherein the traces of the Cu layer 56a are also connected by vias <NUM> to Cu layer 56b. The top polyimide overlay layer 66a may not be needed; in that case, there would be no hindrance of the top polyimide overlay layer 66a to any jumper <NUM> connection.

In another example, a jumper <NUM> (not shown) may connect directly from the Cu layer 56a to the Cu layer 56b. This eliminates the Cu-plated via <NUM> connections, which could be a reliability concern, especially in the flex sheet assembly. However, there is more polyimide topography from the top polyimide overlay layer 66a that the jumper <NUM> needs to reach over. The thickness of the top polyimide overlay layer 66a is typically about ~<NUM>, while the length of the jumper <NUM> typically may be about ~<NUM>. Having the metal of the jumper <NUM> surrounded by large amounts of polyimide from the top polyimide overlay layer 66a may impede the jumper <NUM>, but will also impede ESD, which can be valuable.

In another example, electrical access is provided to the buried Cu layer 56b. This could be accomplished with the via <NUM> connection between Cu layer 56a and Cu layer 56b, or with a direct connection between Cu layer 56a and Cu layer 56b. Also, there may be multiple connections between Cu layer 56a and Cu layer 56b. This redundancy is an important attribute and can be employed when possible.

In another example, the traces of the Cu layers 56a, 56b can be broadened into wider conductors, power lines and common lines that do not have the insulating polyimide layers 66a, 66b between them. Thus, there is more Copper used for conduction, which reduces resistance losses. This does reduce the number of discrete conductors; however, the connection redundancy is preserved.

If there is a problem with the solar cell <NUM> or its connections, they may need to be replaced. Mechanical removal of the solar cell <NUM> and the adhesive <NUM> attaching it to the surface of the flex sheet substrate <NUM> is a known process. This disclosure, on the other hand, is focused on reworking or repairing the electrical connections.

<FIG> illustrates an example where the metal foil interconnect <NUM> from the solar cell <NUM> has separated from the plated Ag or Au layer <NUM> and/or Cu layer 56a. This separation may be the defect causing the rework process. Alternatively, there could be another defect causing this connection to be purposely separated. For example, a cracked solar cell <NUM> would need to be removed including the interconnections to the substrate <NUM>. The separation results in a change in the surface region of the plated Ag or Au layer <NUM> and/or Cu layer 56a, for example, resulting in some debris <NUM>, such as solder residue, roughness, etc..

<FIG> shows one proposed process for repairing the substrate <NUM> in the example of <FIG>, wherein an area of the plated Ag or Au layer <NUM> and/or Cu layer 56a used for the electrical connection is large enough that one or more additional connections can be made in the area. In this example, the replacement solar cell <NUM> is attached to the flex sheet substrate <NUM> using adhesive <NUM>, and the replacement interconnect <NUM> extends from the replacement solar cell <NUM> to make contact with the plated Ag or Au layer <NUM> and/or Cu layer 56a in an adjacent location that avoids the original connection region. The adjacent location in this example has enough conductor for electrical current to flow around the damaged region.

There could be an inventory of CICs with different length interconnects for first assembly, first rework, second rework, etc. Alternatively, a single CIC could be built with an interconnect having a length available for initial assembly and all anticipated rework processes.

Specifically, an electrical connection is repaired by removing a first interconnect <NUM> in a first location in the electrical connection and by forming a second interconnect <NUM> in a second location in the electrical connection different from the first location. The second location may be adjacent the first location, for example, when the plated Ag or Au layer <NUM> and/or Cu layer 56a comprise a connection pad that is large enough to encompass both the first and second locations and to allow electrical current to flow around the first location. In one example, the first interconnect <NUM> in the first location is completely removed, while in another example, a joint remains when the first interconnect <NUM> is removed.

In another proposed repair process, similar to that shown in <FIG>, the area of the plated Ag or Au layer <NUM> and/or Cu layer 56a has been ruptured or divoted. Like <FIG>, a replacement solar cell <NUM> is attached to the flex sheet substrate <NUM> using adhesive <NUM>, and a replacement interconnect <NUM> extends from the replacement solar cell <NUM> to make contact with the plated Ag or Au layer <NUM> and/or Cu layer 56a in an adjacent location that avoids the original connection region, wherein the adjacent location has enough conductor for electrical current to flow around the damaged region.

In another proposed repair process, wherein the original interconnect <NUM> to the solar cell <NUM> is cut, but a joint of the interconnect <NUM> remains intact and bonded to the plated Ag or Au layer <NUM> and/or Cu layer 56a, a replacement interconnect <NUM> is attached to the plated Ag or Au layer <NUM> and/or Cu layer 56a in an adjacent location that avoids the original connection region, wherein the adjacent location has enough conductor for electrical current to flow around the joint of the interconnect <NUM>. Maintaining the joint of the interconnect <NUM> may be preferred as this avoids damage to the plated Ag or Au layer <NUM> and/or Cu layer 56a, for example, by rupturing or divoting.

Different types of repair components may be used, based on two types of interconnects. A first type of repair components could be used in connecting a solar cell <NUM> or bypass diode <NUM> to the substrate <NUM>, while a second type of repair components could be used to connect pairs of corner conductors <NUM> on the substrate <NUM>. The first type of repair components would be the standard interconnects <NUM>, while the second type of repair components would be variations of the standard interconnects <NUM> used for the repair process, i.e., replacement interconnects <NUM>, which have a slightly different structure that moves the electrical connection to an adjacent location from the original connection. It is desirable to position the initial and rework connection points, such that debris <NUM>, cut interconnect <NUM>, or rupturing or divoting of the plated Ag or Au layer <NUM> and/or Cu layer 56a, does not impact repair assembly or current flow.

Another variation is where the type of repair components is designed to allow initial and rework connections to be made using the same interconnect <NUM> structure. Thus, a single interconnect <NUM> is needed. This interconnect <NUM> is used for both the initial build and for rework. There would be initial and rework pairs of connection points on the plated Ag or Au layer <NUM> and/or Cu layer 56a for the initial and rework connections. Again, it is desirable to design these parts and the conducting path on the substrate <NUM>, such that rupture of the conducting path on the substrate <NUM> does not impact conductivity after rework.

In the case where a connection point is inadequate, this interconnect design enables an additional connection point to be used. The interconnect <NUM> can be left in place and an adjacent location of the plated Ag or Au layer <NUM> and/or Cu layer 56a can be used to provide greater reliability. This avoids the possibility of further damage during the rework process.

<FIG> shows how repair components <NUM> are used, according to one example. In this example, the repair components <NUM> comprise replacement interconnects <NUM> connecting the front or back contacts <NUM>, <NUM> to the corner conductors <NUM>, or replacement interconnects <NUM> connecting the bypass diodes <NUM> to the corner conductors <NUM>, or jumpers <NUM> connecting the corner conductors <NUM>. Generally, the following steps are performed: separate interconnects <NUM> at a weld joint, clean out the solar cell <NUM> and/or bypass diode <NUM>, replace the solar cell <NUM> and/or bypass diode <NUM> with a repair unit, and weld the interconnects <NUM> at adjacent locations to the corner conductors <NUM> or front and back contacts <NUM>, <NUM>, or connect a jumper <NUM> between corner conductors <NUM>, wherein all work is performed on a top side of the assembly with no components sticking up.

Preferably, all the electrical connections in this assembly are made by overlapping metal layers. Then, a joint is formed by access from the top for solder or weld processes (laser, resistive, ultrasonic, etc.). This access is very straightforward, as there is no overlapping or folding of conductors. Also, the repair has no material sticking up higher than the original assembly, which is a concern for space solar panels 10a that are often folded tightly for stowage and launch.

Examples of the disclosure may be described in the context of a method <NUM> of fabricating a solar cell <NUM>, solar cell panel 10a and/or satellite, comprising steps <NUM>-<NUM>, as shown in <FIG>, wherein the resulting satellite <NUM> having a solar cell panel 10a comprised of solar cells <NUM> are shown in <FIG>.

As illustrated in <FIG>, during pre-production, exemplary method <NUM> may include specification and design <NUM> of the solar cell <NUM>, solar cell panel 10a and/or satellite <NUM>, and material procurement <NUM> for same. During production, component and subassembly manufacturing <NUM> and system integration <NUM> of the solar cell <NUM>, solar cell panel 10a and/or satellite <NUM> takes place, which include fabricating the solar cell <NUM>, solar cell panel 10a and/or satellite <NUM>. Thereafter, the solar cell <NUM>, solar cell panel 10a and/or satellite <NUM> may go through certification and delivery <NUM> in order to be placed in service <NUM>. The solar cell <NUM>, solar cell panel 10a and/or satellite <NUM> may also be scheduled for maintenance and service <NUM> (which includes modification, reconfiguration, refurbishment, and so on), before being launched.

For the purposes of this description, a system integrator may include without limitation any number of solar cell, solar cell panel, satellite or spacecraft manufacturers and major-system subcontractors; a third party may include without limitation any number of venders, subcontractors, and suppliers; and an operator may be a satellite company, military entity, service organization, and so on.

As shown in <FIG>, a satellite <NUM> fabricated by exemplary method <NUM> may include systems <NUM>, a body <NUM>, solar cell panels 10a comprised of solar cells <NUM>, and one or more antennae <NUM>. Examples of the systems <NUM> included with the satellite <NUM> include, but are not limited to, one or more of a propulsion system <NUM>, an electrical system <NUM>, a communications system <NUM>, and a power system <NUM>. Any number of other systems <NUM> also may be included.

<FIG> is an illustration of the solar cell panel 10a in the form of a functional block diagram, according to one example. The solar cell panel 10a is comprised of the solar cell array <NUM>, which is comprised of one or more of the solar cells <NUM> individually attached to the substrate <NUM>. Each of the solar cells <NUM> absorbs light <NUM> from a light source <NUM> and generates an electrical output <NUM> in response thereto.

At least one of the solar cells <NUM> has at least one cropped corner <NUM> that defines a corner region <NUM>, such that an area <NUM> of the substrate <NUM> remains exposed when the solar cell <NUM> is attached to the substrate <NUM>. When a plurality of solar cells <NUM> are attached to the substrate <NUM>, the corner regions <NUM> of adjacent ones of the solar cells <NUM> are aligned, thereby exposing the area <NUM> of the substrate <NUM>.

The area <NUM> of the substrate <NUM> that remains exposed includes one or more corner conductors <NUM> attached to, printed on, or integrated with the substrate <NUM>, and one or more electrical connections between the solar cells <NUM> and the corner conductors <NUM> are made in a corner region <NUM> resulting from the cropped corner <NUM> of the at least one of the solar cells <NUM>.

The corner region <NUM> resulting from the cropped corner <NUM> includes at least one contact, for example, a front contact <NUM> on a front side of the solar cell <NUM> and/or a back contact <NUM> on a back side of the solar cell <NUM>, for making the electrical connections between the corner conductors <NUM> and the solar cell <NUM>. The electrical connections may comprise up/down or left/right series connections that determine a flow of power through the solar cells <NUM>, and may include one or more bypass diodes <NUM>.

Claim 1:
A substrate (<NUM>) for solar cells (<NUM>), wherein the substrate (<NUM>) is configured such that:
an area (<NUM>) of the substrate (<NUM>) remains exposed when at least one solar cell (<NUM>) having at least one cropped corner (<NUM>) that defines a corner region (<NUM>) is attached to the substrate (<NUM>), wherein the area (<NUM>) of the substrate (<NUM>) that remains exposed includes a corner conductor (<NUM>);
an electrical connection between one of the solar cells (<NUM>) and the corner conductor (<NUM>) can be made in the corner region (<NUM>); and
the electrical connection, which is establishable by connecting a first interconnect (<NUM>) in a first location of the corner conductor (<NUM>) to the one of the solar cells (<NUM>), is repairable by connecting a second interconnect in a second location of the corner conductor (<NUM>) different from the first location, and
wherein an area of the corner conductor (<NUM>) used for the electrical connection is large enough to encompass both the first and second locations.