Patent Description:
Improving contact between current collection portions of the photovoltaic device is important for efficient and durable operation of the device. For example, the electrical junction between the conductive member and bus member is a current collection contact that is important for maintaining function of the photovoltaic device. If the junction is compromised or fails, an open circuit can be created and the photovoltaic device will be rendered inoperable. Accordingly, there exists an ongoing need in the industry for an improved, more robust, and more reliable electrical contact between the conductive member and bus member that can increase the performance of photovoltaic devices. <CIT> discloses a solar cell module that includes a front substrate, a rear substrate facing the front substrate, a plurality of solar cells on the front substrate between the front substrate and the rear substrate, and a protector including a periphery portion formed between a periphery of the front substrate and the plurality of solar cells and a periphery of a rear substrate.

Photovoltaic devices can be formed by deposition of various semiconductor materials and electrode layers as thin (generally recognized in the art as less than <NUM> microns) film layers on a glass substrate. The substrate can then undergo various processing steps, including laser scribing processes, to define and isolate individual photovoltaic cells, define a perimeter edge zone around the photovoltaic cells, and to connect the photovoltaic cells in series. These steps can result in generation of a plurality of individual photovoltaic cells defined within the physical edges of the substrate.

One method for collecting the current from a photovoltaic device is to attach an insulating material (e.g., an insulating tape) lengthwise along the device across the photovoltaic cells. A conductive member (e.g., a conductive foil tape or ribbon) can then be aligned and attached to the insulating material. A bus member (e.g., a bus bar in the form of an adhesive bus tape) can then be attached at opposite longitudinal ends of the device, aligned with the first and last cells, respectively. The bus member can cross over and attach to the conductive member, collect the current from the cells, and transfer the current to the conductive member. The conductive member can be separated in a junction box where leads are connected to separated ends of the conductive member. The leads can provide a means to connect the photovoltaic device to a load, other cells, a grid, and so forth.

The present technology improves reliability and durability of current collecting portions of photovoltaic devices to improve performance of photovoltaic devices. The invention provides a photovoltaic device as defined in Claim <NUM>. For example, the current from a photovoltaic device can be collected by attaching an insulating material (e.g., an insulating tape) lengthwise along the device across the photovoltaic cells and aligning and attaching a conductive member (e.g., a conductive foil tape or ribbon) to the insulating material. A bus member (e.g., a bus bar in the form of an adhesive bus tape) can then be attached at opposite longitudinal ends of the photovoltaic device, aligned with the first and last cells of the photovoltaic device, respectively. In certain configurations, the bus member can cross over and attach to the conductive member, collect the current from the cells, and transfer the current to the conductive member. Where the bus member crosses over near an end of the conductive member, the connection can be described as a T-shaped junction or a T-joint. The T-joint is where the current from the photovoltaic device can accumulate, thus a low and stable contact resistance at that location can be important to maintain good device performance. However, it is possible that during various manufacturing steps, a bus member may be physically displaced by the forces involved in manufacturing, and so it is advantageous to protect the bus member during manufacturing.

Referring now to <FIG>, an embodiment of a photovoltaic device <NUM> (not claimed) is schematically depicted. The photovoltaic device <NUM> can be configured to receive light and transform light into electrical signals, e.g., photons can be absorbed from the light and transformed into electrical signals via the photovoltaic effect. Accordingly, the photovoltaic device <NUM> can define an energy side <NUM> configured to be exposed to a light source such as, for example, the sun. The photovoltaic device <NUM> can also define an opposing side <NUM> offset from the energy side <NUM> such as, for example, by a plurality of material layers. It is noted that the term "light" can refer to various wavelengths of the electromagnetic spectrum such as, but not limited to, wavelengths in the ultraviolet (UV), infrared (IR), and visible portions of the electromagnetic spectrum. "Sunlight," as used herein, refers to light emitted by the sun.

The photovoltaic device <NUM> can include a plurality of layers disposed between the energy side <NUM> and the opposing side <NUM>. As used herein, the term "layer" refers to a thickness of material provided upon a surface. Each layer can cover all or any portion of the surface. In some embodiments, the layers of the photovoltaic device <NUM> can be divided into an array of photovoltaic cells <NUM>. For example, the photovoltaic device <NUM> can be scribed according to a plurality of serial scribes <NUM> and a plurality of parallel scribes <NUM>. The serial scribes <NUM> can extend along a length Y of the photovoltaic device <NUM> and demarcate the photovoltaic cells <NUM> along the length Y of the photovoltaic device <NUM>. The serial scribes <NUM> can be configured to connect neighboring cells of the photovoltaic cells <NUM> serially along a width X of the photovoltaic device <NUM>. Serial scribes <NUM> can form a monolithic interconnect of the neighboring cells, i.e., adjacent to the serial scribe <NUM>. The parallel scribes <NUM> can extend along the width X of the photovoltaic device <NUM> and demarcate the photovoltaic cells <NUM> along the width X of the photovoltaic device <NUM>. Under operations, current <NUM> can predominantly flow along the width X through the photovoltaic cells <NUM> serially connected by the serial scribes <NUM>. Under operations, parallel scribes <NUM> can limit the ability of current <NUM> to flow along the length Y. Parallel scribes <NUM> are optional and can be configured to separate the photovoltaic cells <NUM> that are connected serially into groups <NUM> arranged along length Y. Accordingly, the serial scribes <NUM> and the parallel scribes <NUM> can demarcate the array of the photovoltaic cells <NUM>.

Referring still to <FIG>, the parallel scribes <NUM> can electrically isolate the groups <NUM> of photovoltaic cells <NUM> that are connected serially. In some embodiments, the groups <NUM> of the photovoltaic cells <NUM> can be connected in parallel such as, for example, via electrical bussing. Optionally, the number of parallel scribes <NUM> can be configured to limit a maximum current generated by each group <NUM> of the photovoltaic cells <NUM>. In some embodiments, the maximum current generated by each group <NUM> can be less than or equal to about <NUM> milliamps (mA) such as, for example, less than or equal to about <NUM> mA in one embodiment, less than or equal to about <NUM> mA in another embodiment, or less than or equal to about <NUM> mA in a further embodiment.

Referring collectively to <FIG> and <FIG>, the layers of the photovoltaic device <NUM> (not claimed) can include a substrate <NUM> configured to facilitate the transmission of light into the photovoltaic device <NUM>. The substrate <NUM> can be disposed at the energy side <NUM> of the photovoltaic device <NUM>. Referring now to <FIG>, the substrate <NUM> can have a first surface <NUM> substantially facing the energy side <NUM> of the photovoltaic device <NUM> and a second surface <NUM> substantially facing the opposing side <NUM> of the photovoltaic device <NUM>. One or more layers of material can be disposed between the first surface <NUM> and the second surface <NUM> of the substrate <NUM>.

The substrate <NUM> can include a transparent layer <NUM> having a first surface <NUM> substantially facing the energy side <NUM> of the photovoltaic device <NUM> and a second surface <NUM> substantially facing the opposing side <NUM> of the photovoltaic device <NUM>. In some embodiments, the second surface <NUM> of the transparent layer <NUM> can form the second surface <NUM> of the substrate <NUM>. The transparent layer <NUM> can be formed from a substantially transparent material such as, for example, glass. Suitable glass can include soda-lime glass, or any glass with reduced iron content. The transparent layer <NUM> can have any suitable transmittance, including about <NUM> to about <NUM>,<NUM> in some embodiments, or about <NUM> to about <NUM> in other embodiments. The transparent layer <NUM> may also have any suitable transmission percentage, including, for example, more than about <NUM>% in one embodiment, more than about <NUM>% in another embodiment, more than about <NUM>% in yet another embodiment, more than about <NUM>% in a further embodiment, or more than about <NUM>% in still a further embodiment. In one embodiment, transparent layer <NUM> can be formed from a glass with about <NUM>% transmittance, or more. Optionally, the substrate <NUM> can include a coating <NUM> applied to the first surface <NUM> of the transparent layer <NUM>. The coating <NUM> can be configured to interact with light or to improve durability of the substrate <NUM> such as, but not limited to, an antireflective coating, an antisoiling coating, or a combination thereof.

Referring again to <FIG>, the photovoltaic device <NUM> can include a barrier layer <NUM> configured to mitigate diffusion of contaminants (e.g., sodium) from the substrate <NUM>, which could result in degradation or delamination. The barrier layer <NUM> can have a first surface <NUM> substantially facing the energy side <NUM> of the photovoltaic device <NUM> and a second surface <NUM> substantially facing the opposing side <NUM> of the photovoltaic device <NUM>. In some embodiments, the barrier layer <NUM> can be provided adjacent to the substrate <NUM>. For example, the first surface <NUM> of the barrier layer <NUM> can be provided upon the second surface <NUM> of the substrate <NUM>. The phrase "adjacent to," as used herein, means that two layers are disposed contiguously and without any intervening materials between at least a portion of the layers.

Generally, the barrier layer <NUM> can be substantially transparent, thermally stable, with a reduced number of pin holes and having high sodium-blocking capability, and good adhesive properties. Alternatively or additionally, the barrier layer <NUM> can be configured to apply color suppression to light. The barrier layer <NUM> can include one or more layers of suitable material, including, but not limited to, tin oxide, silicon dioxide, aluminum-doped silicon oxide, silicon oxide, silicon nitride, or aluminum oxide. The barrier layer <NUM> can have any suitable thickness bounded by the first surface <NUM> and the second surface <NUM>, including, for example, more than about <NUM>Å in one embodiment, more than about <NUM>Å in another embodiment, or less than about <NUM>Å in a further embodiment.

Referring still to <FIG>, the photovoltaic device <NUM> can include a transparent conductive oxide (TCO) layer <NUM> configured to provide electrical contact to transport charge carriers generated by the photovoltaic device <NUM>. The TCO layer <NUM> can have a first surface <NUM> substantially facing the energy side <NUM> of the photovoltaic device <NUM> and a second surface <NUM> substantially facing the opposing side <NUM> of the photovoltaic device <NUM>. In some embodiments, the TCO layer <NUM> can be provided adjacent to the barrier layer <NUM>. For example, the first surface <NUM> of the TCO layer <NUM> can be provided upon the second surface <NUM> of the barrier layer <NUM>. Generally, the TCO layer <NUM> can be formed from one or more layers of n-type semiconductor material that is substantially transparent and has a wide band gap. Specifically, the wide band gap can have a larger energy value compared to the energy of the photons of the light, which can mitigate undesired absorption of light. The TCO layer <NUM> can include one or more layers of suitable material, including, but not limited to, tin dioxide, doped tin dioxide (e.g., F-SnO<NUM>), indium tin oxide, or cadmium stannate.

The photovoltaic device <NUM> can include a buffer layer <NUM> configured to provide an insulating layer between the TCO layer <NUM> and any adjacent semiconductor layers. The buffer layer <NUM> can have a first surface <NUM> substantially facing the energy side <NUM> of the photovoltaic device <NUM> and a second surface <NUM> substantially facing the opposing side <NUM> of the photovoltaic device <NUM>. In some embodiments, the buffer layer <NUM> can be provided adjacent to the TCO layer <NUM>. For example, the first surface <NUM> of the buffer layer <NUM> can be provided upon the second surface <NUM> of the TCO layer <NUM>. The buffer layer <NUM> may include material having higher resistivity than the TCO later <NUM>, including, but not limited to, intrinsic tin dioxide, zinc magnesium oxide (e.g., Zn<NUM>-xMgxO), silicon dioxide (SnO<NUM>), aluminum oxide (Al<NUM>O<NUM>), aluminum nitride (AlN), zinc tin oxide, zinc oxide, tin silicon oxide, or any combination thereof. In some embodiments, the material of the buffer layer <NUM> can be configured to substantially match the band gap of an adjacent semiconductor layer (e.g., an absorber). The buffer layer <NUM> may have any suitable thickness between the first surface <NUM> and the second surface <NUM>, including, for example, more than about <NUM>Å in one embodiment, between about <NUM>Å and about <NUM>Å in another embodiment, or between about <NUM>Å and about <NUM>Å in a further embodiment.

Referring still to <FIG>, the photovoltaic device <NUM> can include an absorber layer <NUM> configured to cooperate with another layer and form a p-n junction within the photovoltaic device <NUM>. Accordingly, absorbed photons of the light can free electron-hole pairs and generate carrier flow, which can yield electrical power. The absorber layer <NUM> can have a first surface <NUM> substantially facing the energy side <NUM> of the photovoltaic device <NUM> and a second surface <NUM> substantially facing the opposing side <NUM> of the photovoltaic device <NUM>. A thickness of the absorber layer <NUM> can be defined between the first surface <NUM> and the second surface <NUM>. The thickness of the absorber layer <NUM> can be between about <NUM> to about <NUM> such as, for example, between about <NUM> to about <NUM> in one embodiment, or between about <NUM> to about <NUM> in another embodiment.

According to the embodiments described herein, the absorber layer <NUM> can be formed from a p-type semiconductor material having an excess of positive charge carriers, i.e., holes or acceptors. The absorber layer <NUM> can include any suitable p-type semiconductor material such as group II-VI semiconductors. Specific examples include, but are not limited to, semiconductor materials comprising cadmium, tellurium, selenium, or any combination thereof. Suitable examples include, but are not limited to, ternaries of cadmium, selenium and tellurium (e.g., CdSexTe<NUM>-x), or a compound comprising cadmium, selenium, tellurium, and one or more additional element. The absorber layer <NUM> may further comprise one or more dopants. Photovoltaic devices may include a plurality of absorber materials.

In embodiments where the absorber layer <NUM> comprises tellurium and cadmium, the atomic percent of the tellurium can be greater than or equal to about <NUM> atomic percent and less than or equal to about <NUM> atomic percent such as, for example, greater than about <NUM> atomic percent and less than about <NUM> atomic percent in one embodiment, greater than about <NUM> atomic percent and less than about <NUM> atomic percent in a further embodiment, or greater than about <NUM> atomic percent and less than about <NUM> atomic percent in yet another embodiment. Alternatively or additionally, the atomic percent of the tellurium in the absorber layer <NUM> can be greater than about <NUM> atomic percent such as, for example, greater than about <NUM>% in one embodiment. It is noted that the atomic percent described herein is representative of the entirety of the absorber layer <NUM>, the atomic percentage of material at a particular location within the absorber layer <NUM> can vary with thickness compared to the overall composition of the absorber layer <NUM>.

In embodiments where the absorber layer <NUM> comprises selenium and tellurium, the atomic percent of the selenium in the absorber layer <NUM> can be greater than about <NUM> atomic percent and less or equal to than about <NUM> atomic percent such as, for example, greater than about <NUM> atomic percent and less than about <NUM> atomic percent in one embodiment, greater than about <NUM> atomic percent and less than about <NUM> atomic percent in another embodiment, or greater than about <NUM> atomic percent and less than about <NUM> atomic percent in a further embodiment. It is noted that the concentration of tellurium, selenium, or both can vary through the thickness of the absorber layer <NUM>. For example, when the absorber layer <NUM> comprises a compound including selenium at a mole fraction of x and tellurium at a mole fraction of <NUM>-x (SexTe<NUM>-x), x can vary in the absorber layer <NUM> with distance from the first surface <NUM> of the absorber layer <NUM>.

Referring still to <FIG>, the absorber layer <NUM> can be doped with a dopant configured to manipulate the charge carrier concentration. In some embodiments, the absorber layer <NUM> can be doped with a Group I or V dopant such as, for example, copper, arsenic, phosphorous, antimony, or a combination thereof. The total density of the dopant within the absorber layer <NUM> can be controlled. Alternatively or additionally, the amount of the dopant can vary with distance from the first surface <NUM> of the absorber layer <NUM>. In some embodiments, dopants are introduced during a passivation step in the manufacturing process. Passivation may include, for example, treatment with CdCl<NUM> or other halide compounds, and resulting dopants may include chlorine or other halogens. Additionally, the amount of a selected dopant can vary with distance from the first surface <NUM> of the absorber layer <NUM>.

According to the embodiments provided herein, the p-n junction can be formed by providing the absorber layer <NUM> sufficiently close to a portion of the photovoltaic device <NUM> having an excess of negative charge carriers, i.e., electrons or donors. In some embodiments, the absorber layer <NUM> can be provided adjacent to n-type semiconductor material. Alternatively, one or more intervening layers can be provided between the absorber layer <NUM> and n-type semiconductor material. In some embodiments, the absorber layer <NUM> can be provided adjacent to the buffer layer <NUM>. For example, the first surface <NUM> of the absorber layer <NUM> can be provided upon the second surface <NUM> of the buffer layer <NUM>.

Referring now to <FIG>, in some embodiments, a photovoltaic device <NUM> (not claimed) can include a window layer <NUM> comprising n-type semiconductor material. The absorber layer <NUM> can be formed adjacent to the window layer <NUM>. The window layer <NUM> can have a first surface <NUM> substantially facing the energy side <NUM> of the photovoltaic device <NUM> and a second surface <NUM> substantially facing the opposing side <NUM> of the photovoltaic device <NUM>. In some embodiments, the window layer <NUM> can be positioned between the absorber layer <NUM> and the TCO layer <NUM>. In one embodiment, the window layer <NUM> can be positioned between the absorber layer <NUM> and the buffer layer <NUM>. The window layer <NUM> can include any suitable material, including, for example, cadmium sulfide, zinc sulfide, cadmium zinc sulfide, zinc magnesium oxide, or any combination thereof. The material of the window layer <NUM> can include dopants.

Referring collectively to <FIG> and <FIG>, the photovoltaic device <NUM> (not claimed), <NUM> can include a back contact layer <NUM> configured to mitigate undesired alteration of the dopant and to provide electrical contact to the absorber layer <NUM>. The back contact layer <NUM> can have a first surface <NUM> substantially facing the energy side <NUM> of the photovoltaic device <NUM> and a second surface <NUM> substantially facing the opposing side <NUM> of the photovoltaic device <NUM>. A thickness of the back contact layer <NUM> can be defined between the first surface <NUM> and the second surface <NUM>. The thickness of the back contact layer <NUM> can be between about <NUM> to about <NUM> such as, for example, between about <NUM> to about <NUM> in one embodiment.

In some embodiments, the back contact layer <NUM> can be provided adjacent to the absorber layer <NUM>. For example, the first surface <NUM> of the back contact layer <NUM> can be provided upon the second surface <NUM> of the absorber layer <NUM>. In some embodiments, the back contact layer <NUM> can include binary or ternary combinations of materials from Groups I, II, VI, such as for example, one or more layers containing zinc, copper, cadmium, and tellurium in various compositions. Further exemplary materials include, but are not limited to, zinc telluride doped with copper telluride, or zinc telluride alloyed with copper telluride.

The photovoltaic device <NUM> includes a conducting layer <NUM> configured to provide electrical contact with the absorber layer <NUM>. The conducting layer <NUM> has a first surface <NUM> substantially facing the energy side <NUM> of the photovoltaic device <NUM> and a second surface <NUM> substantially facing the opposing side <NUM> of the photovoltaic device <NUM>. In some embodiments, the conducting layer <NUM> can be provided adjacent to the back contact layer <NUM>. For example, the first surface <NUM> of the conducting layer <NUM> can be provided upon the second surface <NUM> of the back contact layer <NUM>. The conducting layer <NUM> can include any suitable conducting material such as, for example, one or more layers of nitrogen-containing metal, silver, nickel, copper, aluminum, titanium, palladium, chrome, molybdenum, gold, or the like. Suitable examples of a nitrogen-containing metal layer can include aluminum nitride, nickel nitride, titanium nitride, tungsten nitride, selenium nitride, tantalum nitride, or vanadium nitride.

The photovoltaic device <NUM>, <NUM> can include a back support <NUM> configured to cooperate with the substrate <NUM> to form a housing for the photovoltaic device <NUM>. The back support <NUM> can be disposed at the opposing side <NUM> of the photovoltaic device <NUM>. For example, the back support <NUM> can be formed adjacent to the conducting layer <NUM>. The back support <NUM> can include any suitable material, including, for example, glass (e.g., soda-lime glass). In some embodiments, an encapsulation layer can also function as the back support <NUM>.

Referring collectively to <FIG>, <FIG>, manufacturing of a photovoltaic device <NUM>, <NUM> (not claimed) generally includes sequentially disposing functional layers or layer precursors in a "stack" of layers through one or more thin film deposition processes, including, but not limited to, sputtering, spray, evaporation, molecular beam deposition, pyrolysis, closed space sublimation (CSS), pulse laser deposition (PLD), chemical vapor deposition (CVD), electrochemical deposition (ECD), atomic layer deposition (ALD), or vapor transport deposition (VTD). VTD may be preferred for greater throughput quality. Manufacturing may also include annealing and passivating steps.

Manufacturing of photovoltaic devices <NUM>, <NUM> can further include the selective removal of the certain layers of the stack of layers, i.e., scribing, to divide the photovoltaic device into <NUM>, <NUM> a plurality of photovoltaic cells <NUM>. For example, the serial scribes <NUM> can comprise a first isolation scribe <NUM> (also referred to as a P1 scribe), a series connecting scribe <NUM> (also referred to as a P2 scribe), and a second isolation scribe <NUM> (also referred to as a P3 scribe). The first isolation scribe <NUM> can be formed to ensure that the TCO layer <NUM> is electrically isolated between cells <NUM>. Specifically, the first isolation scribe <NUM> can be formed though the TCO layer <NUM>, the buffer layer <NUM>, and the absorber layer <NUM> of photovoltaic device <NUM>, or though the TCO layer <NUM>, the buffer layer <NUM>, the window layer <NUM>, and the absorber layer <NUM> of the photovoltaic device <NUM>. The first isolation scribe <NUM> bounding the reverse operation cell <NUM> can be filled with a dielectric material <NUM>.

Referring again to <FIG> and <FIG>, the series connecting scribe <NUM> can be formed to electrically connect photovoltaic cells <NUM> in series. For example, the series connecting scribe <NUM> can be utilized to provide a conductive path from the conductive layer <NUM> of one of the photovoltaic cells <NUM> to the TCO layer <NUM> of another of the photovoltaic cells <NUM>. The series connecting scribe <NUM> can be formed through the absorber layer <NUM>, and the back contact layer <NUM> of photovoltaic device <NUM>, or through the window layer <NUM>, the absorber layer <NUM>, and the back contact layer <NUM> of the photovoltaic device <NUM>. Optionally, the series connecting scribe <NUM> can be formed through some or all of the buffer layer <NUM>. Accordingly, the series connecting scribe <NUM> can be formed after the back contact layer <NUM> is deposited. The series connecting scribe <NUM> can then be filled with a conducting material such as, but not limited to, the material of the conducting layer <NUM>. In some embodiments, the conductive material can be more conductive in reverse bias relative to forward bias.

The second isolation scribe <NUM> can be formed to isolate the back contact <NUM> into individual cells <NUM>. The second isolation scribe <NUM> can be formed through the conductive layer <NUM>, the back contact layer <NUM>, and at least a portion of the absorber layer <NUM>. The second isolation scribe <NUM> can be filled with a dielectric material <NUM>.

Referring collectively to <FIG> and <FIG>, a parallel scribe <NUM> (also referred to as a P4 scribe) can be formed to isolate groups <NUM> of cells <NUM> from one another. In some embodiments, each group <NUM> can comprise multiple photovoltaic cells <NUM> connected in series such as, for example, via the series connecting scribe <NUM>. The parallel scribe <NUM> can be formed through the conductive layer <NUM>, the back contact layer <NUM>, the absorber layer <NUM>, the buffer layer <NUM>, the TCO layer <NUM>, the barrier layer <NUM>, and the window layer <NUM> (when present). According to the embodiments provided herein, each of the parallel scribe <NUM>, the first isolation scribe <NUM>, the series connecting scribe <NUM>, and the second isolation scribe <NUM> can be formed via laser cutting or laser scribing. In some embodiments, the parallel scribe <NUM> can be filled with a dielectric material.

With reference now to <FIG>, an embodiment of the photovoltaic device <NUM>, <NUM> (not claimed) is shown. A plurality of photovoltaic cells <NUM> is formed on a substrate <NUM>, where each of the photovoltaic cells <NUM> includes an absorber layer <NUM> and a conducting layer <NUM>, the conducting layer <NUM> having a first surface <NUM> and a second surface <NUM>, the first surface <NUM> of the conducting layer <NUM> facing the absorber layer <NUM>. A bus member <NUM> is electrically coupled to the second surface <NUM> of the conducting layer <NUM> of at least one of the plurality of photovoltaic cells <NUM>, where the bus member <NUM> is operable to collect current generated by the plurality of photovoltaic cells <NUM>. A conductive member <NUM> is provided that has a portion <NUM> thereof adjacent a portion <NUM> of the bus member <NUM> to define a connection region <NUM> therebetween. The conductive member <NUM> extends from the connection region <NUM> over a portion of the plurality of photovoltaic cells <NUM>. An insulating material <NUM> electrically insulates the conductive member <NUM> from the second surface <NUM> of the conducting layer <NUM> of the portion of the plurality of photovoltaic cells <NUM>. An electrically conductive adhesive layer is disposed between the bus member <NUM> and the conductive member <NUM> within the connection region <NUM>. Direct contact is made between the bus member <NUM> and the conductive member <NUM> through the electrically conductive adhesive layer within the connection region <NUM>.

With reference again to <FIG>, it can be seen that the portion <NUM> of the conductive member <NUM> adjacent the portion <NUM> of the bus member <NUM> that defines the connection region <NUM> therebetween is provided by having the portion <NUM> of the bus member <NUM> overlap the portion <NUM> of the conductive member <NUM>. It can be further seen that the bus member <NUM> crosses over the conductive member <NUM> at the connection region <NUM>. In this way, the bus member <NUM> can be electrically coupled to the second surface <NUM> of the conducting layer <NUM> of one or more photovoltaic cells <NUM> on each side of the conductive member <NUM>, where the bus member <NUM> is hence operable to collect current generated by the photovoltaic cells <NUM> on each side of the conductive member <NUM>.

After the layer stack with scribes is formed, bussing may be added as described above and in more detail below, and the photovoltaic device may be assembled. An encapsulation layer may be applied and the semiconductor layers may be sealed relative to rain, snow, and other metrological elements. Referring now to <FIG>, the substrate <NUM> and the back support <NUM> may be laminated together so as to encapsulate the photovoltaic cells <NUM>. The substrate <NUM> has a width and a length and the back support <NUM> may have substantially the same width and length as the substrate <NUM>. Each of the substrate <NUM> and the back support <NUM> can include any suitable protective material such as, for example, borosilicate glass, float glass, soda lime glass, carbon fiber, or polycarbonate. Alternatively, the back support <NUM> may be any suitable material such as a polymer-based back sheet. The back support <NUM> and substrate <NUM> can protect the various layers of the photovoltaic device <NUM> from exposure to moisture and other environmental hazards. <FIG> shows a perspective view of the back side of an example of a completed module. The module assembly <NUM> may include the layers described and depicted in <FIG>, as well as bussing, encapsulation, and electrical connectors. The photovoltaic module assembly <NUM> may be configured to connect to a load through electrical connectors which pass through the junction box <NUM>. The electrical connectors may include a first cable <NUM> with a first terminal <NUM>, and a second cable <NUM> with a second terminal <NUM>. The module assembly <NUM> may further include a supporting frame, bracket, or mount <NUM>.

Referring now to <FIG> and <FIG>, the bussing may be added in a variety of manners and configurations. The bus members <NUM> can be metallic strips that may be added to the front and back sides of the photovoltaic device <NUM> to conduct direct current generated by the photovoltaic cells <NUM>. In general, two bus members <NUM> may be added to the photovoltaic device <NUM>, as described below and depicted in <FIG>, to conduct direct current generated by the photovoltaic cells <NUM>. Bus members <NUM> may also be referred to as busbars, bus conductors, common conductors, photovoltaic ribbon, or buses. Each bus member <NUM> can function as one of a common positive and negative conductor, electrically connected to the first cells <NUM> in a series or the last cells <NUM> in a series, for example.

It is understood that although <FIG> depict bussing configurations near a peripheral edge <NUM>, the photovoltaic device <NUM> may have a second peripheral edge on an opposing side and a corresponding bussing configuration near the second peripheral edge. In such embodiments, the bus member <NUM> near the peripheral edge <NUM> may act as a positive bus, and a second bus member near the second peripheral edge may act as a negative bus. For example, referring now to <FIG>, a photovoltaic device <NUM> (not claimed) may have a first peripheral edge 340a on a first side <NUM> with a first bus member 224a extending along the length Y and a first conductive member 226a extending along the width X, and a second peripheral edge 340b on an opposing second side <NUM> with a second bus member 224b extending along the length Y and a second conductive member 226b extending along the width X. The photovoltaic device <NUM> may have a first side edge <NUM> and a second side edge <NUM> extending along the width X on opposing sides of the length Y, and each of the first side edge <NUM> and second side edge <NUM> may include a dead area similar to each peripheral edge 340a, 340b. However, for ease of illustration and explanation, only one peripheral edge <NUM> and one set of bus member <NUM> and conductive member <NUM> are depicted in <FIG> and referred to. <FIG> depict one set of bussing components which may be replicated on an opposing side of the photovoltaic device <NUM>. Thus, for example, when referring to <FIG>, it is understood that the first photovoltaic cell 200a may alternatively be the last photovoltaic cell.

Referring now to <FIG>, a photovoltaic device <NUM> (not claimed) is depicted at certain sequential stages of a manufacturing process. The photovoltaic cells <NUM> may include a first cell 200a closest among the photovoltaic cells <NUM> to a dead area <NUM>, which is formed by a suitable ablation method on a region of the photovoltaic device <NUM> extending inwardly from the periperhal edge <NUM> of the photovoltaic device <NUM>. The first photovoltaic cell 200a is the photovoltaic cell <NUM> that is closest to the peripheral edge <NUM> of the photovoltaic device <NUM>. In this embodiment, the first photovoltaic cell 200a is larger than each of the neighboring photovoltaic cells 200b, 200c, 200d, as described in more detail below. The photovoltaic cells <NUM> are separated by the parallel scribes <NUM>.

Referring now to <FIG>, the insulating material <NUM> may be added on top of the photovoltaic cells <NUM>, so as to extend over at least a portion of the first photovoltaic cell 200a. The insulating material <NUM> may extend over a plurality of the photovoltaic cells <NUM>. <FIG> depicts the first photovoltaic cell 200a, the second photovoltaic cell 200b, the third photovoltaic cell 200c, and the fourth photovoltaic cell 200d, but it is understood that the insulating material <NUM> may be added over any number of the photovoltaic cells <NUM>. Also, the insulating material <NUM> does not need to extend over the entire first photovoltaic cell 200a. Rather, as seen in <FIG>, the insulating material <NUM> may extend over only a portion of the first cell 200a, in which case the insulating material <NUM> does not contact the dead area <NUM>.

The insulating material <NUM> may be, for example, a double sided tape. However, other electrically insulating materials are possible. The insulating material <NUM> may electrically insulate the conductive member <NUM> from the second surface <NUM> of the conducting layer <NUM> of the photovoltaic cells <NUM> that the insulating material <NUM> touches, and may also hold the conductive member <NUM> in place.

Referring now to <FIG>, the conductive member <NUM> may be added over the insulating material <NUM>, such that the conductive member <NUM> is not in direct contact with the photovoltaic cells <NUM>. Rather, the conductive member <NUM> may be in direct contact with the insulating material <NUM>. In this manner, the insulating material <NUM> may electrically insulate the conductive member <NUM> from the photovoltaic cells <NUM>. The conductive member <NUM> may be any conductive material such as, but not limited to, a metal.

Referring now to <FIG>, the bus member <NUM> may be added on top of the conductive member <NUM> so as to extend across the first photovoltaic cell 200a, and to overlap the conductive member <NUM>. The bus member <NUM> may be electrically coupled to the second surface <NUM> of the conducting layer <NUM> of the first photovoltaic cell 200a, such that the bus member <NUM> is operable to collect current generated by the plurality of photovoltaic cells <NUM>. The bus member <NUM> may directly contact the first photovoltaic cell 200a, or the bus member <NUM> may alternatively be coupled to the first photovoltaic cell 200a through a conductive material or conductive adhesive. With reference to <FIG>, the bus member <NUM> may extend along the length Y from a location near a dead area at the first side edge <NUM> of the photovoltaic device <NUM> to a location near a dead area at the second side edge <NUM> of the photovoltaic device <NUM>. The bus member <NUM> may have a width W that extends in its entirety over the conductive member <NUM>, and over the first photovoltaic cell 200a. As noted above, the bus member <NUM> may be connected to the conductive member <NUM> through an electrically conductive adhesive layer. In other embodiments, the bus member <NUM> may directly contact the conductive member <NUM>. The bus member <NUM> is operable to carry photocurrent generated from the cells <NUM> to the conductive member <NUM>. The conductive member <NUM>, in turn, may be operable to carry the photocurrent to the junction box <NUM>.

Referring again to <FIG>, the overlap of the bus member <NUM> over the conductive member <NUM> forms the configuration known as a T-joint <NUM>. The bus member <NUM> may cross over the conductive member <NUM> in a substantially orthogonal manner. However, it is not necessary that the overlap of the bus member <NUM> over the conductive member <NUM> be substantially orthogonal.

Referring now to <FIG>, an edge seal <NUM> may be added over a portion of the photovoltaic device <NUM>, after adding the bus member <NUM>. The edge seal <NUM> may extend along the length Y from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM>, and may be at or near the peripheral edge <NUM> of the photovoltaic device <NUM>. The edge seal <NUM> may cover a portion of the first photovoltaic cell 200a. A portion of the dead area <NUM> may remain between the edge seal <NUM> and the peripheral edge <NUM> of the photovoltaic device <NUM>. However, in other embodiments, the edge seal <NUM> extends to the peripheral edge <NUM> such that there is no dead area <NUM> uncovered by the edge seal <NUM>. In the embodiment depicted in <FIG>, the edge seal <NUM> does not cover the bus member <NUM>. Thus, in this embodiment, the edge seal <NUM> does not cover the T-joint <NUM>.

The edge seal <NUM> may protect the photovoltaic device <NUM> from moisture intrusion, foreign substances, and other environmental hazards. The edge seal <NUM> can also serve as an adhesive that bonds the device <NUM> together. Polyisobutylene (PIB), also known as butyl rubber, is a possible sealant material for the edge seal <NUM>, though other examples of edge seal materials include, but are not limited to, opaque polymeric compounds. The edge seal material may also be dyed any desired color, and may contain any colorant. The edge seal material that forms the edge seal <NUM> may be applied in liquid hot melt form, in tape form, or by any other known technology. The liquid hot melt edge seal material may cool to a solid state when the substrate <NUM> and the back support <NUM> are combined during manufacturing. The cured edge seal material may be applied in liquid hot melt form during manufacturing using a hot melt process which may include a hot melt dispensing device, for example. The hot melt dispensing device may dispense the liquid edge seal material through an applicator attached to a hose, such that the liquid edge seal material is pumped from a dispensing pump connected to an edge seal material container. The edge seal material may also include a dessicant material.

Referring now to <FIG>, an interlayer <NUM> may be added to the photovoltaic device <NUM>. The interlayer <NUM> may extend along the length Y from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM> of the photovoltaic device <NUM>. The interlayer <NUM> may be applied to extend over a portion of the first photovoltaic cell 200a, and may completely cover the bus member <NUM> from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM>. In this manner, the bus member <NUM> is protected by the interlayer <NUM> during subsequent manufacturing processes, and is therefore less susceptible to being moved from the forces involved in subsequent manfuacturing steps. Portions of the first photovoltaic cell 200a, the insulating member <NUM>, and the conductive member <NUM> may remain uncovered by both the interlayer <NUM> and the edge seal <NUM>.

The interlayer <NUM> may serve multiple functions. First, the interlayer <NUM> may serve as a moisture barrier between the back support <NUM> and the plurality of photovoltaic cells <NUM>. By being a moisture barrier, the interlayer <NUM> may prevent moisture-induced corrosion from occurring inside the photovoltaic device <NUM>. This, in turn, may increase the device's life expectancy. Second, the interlayer <NUM> may serve as an electrical insulator between the electrically conductive core of the photovoltaic device <NUM> and any accessible points exterior to the photovoltaic device <NUM>. For example, the interlayer <NUM> may limit or prevent leakage current from passing from the back contact through the back support <NUM> of the photovoltaic device <NUM>. Third, the interlayer <NUM> may serve as a bonding agent that attaches the back support <NUM> to the rest of the photovoltaic device <NUM>. During manufacturing, a lamination process may heat the interlayer <NUM> under vacuum to allow the material to wet-out any adjacent adherent surfaces, and in some cases initiate a cross-linking reaction. This process may promote bonding between the interlayer <NUM> and the back support <NUM> as well as between the interlayer <NUM> and the conducting layer <NUM>. The interlayer <NUM>, therefore, may serve as a bonding agent within the photovoltaic device <NUM>.

The interlayer <NUM> may include any suitable materials such as, for example, ethylene (EVA), polyvinyl butyral (PVB), polydimethylsiloxane (PDMS), polyiso-butylene (PIB), polyolefin, thermoplasatic polyurethane (TPU), polyurethane, epoxy, silicone, ionomer, or a combination thereof. In some embodiments, the interlayer <NUM> may include a base material and a filler material. The base material may be any of ethylene (EVA), polyvinyl butyral (PVB), polydimethylsiloxane (PDMS), polyiso-butylene (PIB), polyolefin, thermoplasatic polyurethane (TPU), polyurethane, epoxy, silicone, ionomer, or a combination thereof. The filler material can contain a flame retardant material, a dessicant material, a pigment, an inert material, or any combination thereof.

As noted above, the photovoltaic device depicted in <FIG> (not claimed) may include a first photovoltaic cell 200a that is larger in size than the neighboring photovoltaic cells 200b, 200c, 200d. Specifically, the first photovoltaic cell 200a may extend for a distance d<NUM> that is larger than each of the distance d<NUM> that the second photovoltaic cell 200b extends, the distance d<NUM> that the third photovoltaic cell 200c extends, and the distance d<NUM> that the fourth photovoltaic cell 200d extends. This allows for covering of the bus member <NUM> with the interlayer <NUM> without sacrificing edge seal width that is important to prevent moisture ingress from the environment. If the first photovoltaic cell 200a were not larger than the other photovoltaic cells 200b, 200c, 200d, then the interlayer <NUM> and the edge seal <NUM> may run on top of each other during the manufacturing process unless the edge seal <NUM> width is reduced, both of which would reduce the effectiveness of the edge seal <NUM> as a moisture barrier. Furthermore, if the first photovoltaic cell 200a were not larger than the other photovoltaic cells 200b, 200c, 200d, then the interlayer <NUM> would be deposited over a larger area of the photovoltaic device <NUM> - and therefore require a greater amount of interlayer material - in order to reach and cover the bus member <NUM>, which extends over and is electrically coupled to the first photovoltaic cell 200a so as to collect the current generated from all of the photovoltaic cells <NUM> connected in series. Thus, as seen in <FIG>, the interlayer <NUM> may cover the bus member <NUM>, and may cover a portion of the first photovoltaic cell 200a to do so. Consequently, the interlayer <NUM> may protect the bus member <NUM> during subsequent manufacturing steps, during which the bus member <NUM> may otherwise become physically dislodged. However, because the photovoltaic cells <NUM> are connected in series, the larger cell size of the first photovoltaic cell 200a does not result in a greater electric current being passed through the photovoltaic cells <NUM> to the bus member <NUM>. Therefore, improved device efficiency can be achieved with bussing configurations that reduce the size of the first photovoltaic cell 200a while still protecting the bus member <NUM>. Provided herein are photovoltaic devices having bussing configurations that provide for a reduction of the first photovoltaic cell size, and therefore realize higher device efficiency, while still protecting the bus member <NUM> during manfucturing.

Referring now to <FIG>, a photovoltaic device <NUM> (not claimed) at certain sequential steps of a manufacturing process is depicted. As seen in <FIG>, a dead area <NUM> abutting the peripheral edge <NUM> of the photovoltaic device <NUM> may be created by a suitable ablation method. The photovoltaic device <NUM> may include a first photovoltaic cell 200a adjacent to the dead area <NUM>, a second photovoltaic cell 200b, a third photovoltaic cell 200c, and a fourth photovoltaic cell 200d, separated by the serial scribes <NUM>. It is understood that four photovoltaic cells <NUM> are depicted for illustration purposes, but the number of photovoltaic cells <NUM> is not particularly limited. In this embodiment, the first photovoltaic cell 200a has a smaller size compared to in the embodiment depicted in <FIG> (not claimed). The distance d<NUM> that the first photovoltaic cell 200a extends may still be larger than each of the distances d<NUM>, d<NUM>, d<NUM> that the neighboring photovoltaic cells 200d, 200c, 200d extend, but the distance d<NUM> that the first photovoltaic cell 200a extends may be smaller than the distance d<NUM> that the first photovoltaic cell 200a extends in the embodiment depicted in <FIG> (not claimed).

Referring now to <FIG>, the insulating material <NUM> may be added over the photovoltaic cells <NUM> in the same manner as previously described. The insulating material <NUM> may cover any number of the photovoltaic cells <NUM>, provided that the insulating material <NUM> extends over at least a portion of the first photovoltaic cell 200a. It is not necessary that the insulating material <NUM> extend to the dead area <NUM>, though the insulating material <NUM> may extend to the dead area <NUM>.

Referring now to <FIG>, the conductive member <NUM> may be deposited on the insulating material <NUM>. The conductive member <NUM> may not be in direct contact with the photovoltaic cells <NUM>, but may be in direct contact with the insulating material <NUM>. In this manner, the insulating material <NUM> may serve to electrically insulate the conductive member <NUM> from the second surface <NUM> of the conducting layer <NUM> of the photovoltaic cells <NUM>. The insulating material <NUM> may also hold the conductive member <NUM> in place during subsequent manufacturing steps.

Referring now to <FIG>, the bus member <NUM> may be added over the conductive member <NUM>, insulating material <NUM>, and the first photovoltaic cell 200a. The bus member <NUM> may extend along the length Y from a location near a dead area at the first side edge <NUM> of the photovoltaic device <NUM> to a location near a dead area at the second side edge <NUM> of the photovoltaic device <NUM>. The bus member <NUM> may have a width W that extends in its entirety over the conductive member <NUM>, and over the first photovoltaic cell 200a. The T-joint <NUM> is formed by the bus member <NUM> overlapping the conductive member <NUM>, which may be in a substantially orthogonal manner (thus resembling a "T" shape). However, it is not necessary that the extension of the bus member <NUM> over the conductive member <NUM> be substantially orthogonal.

Referring now to <FIG>, the edge seal <NUM> may be added over the dead area <NUM> and the T-joint <NUM> from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM>, so as to completely cover the T-joint <NUM>. It is not necessary that the edge seal <NUM> extend all the way to the peripheral edge <NUM>. Rather, some portion of the dead area <NUM> may remain uncovered by the edge seal <NUM>. However, in some embodiments, the edge seal <NUM> may extend all the way to the peripheral edge <NUM>, leaving no dead area <NUM> uncovered by the edge seal <NUM>. Advantageously, in the embodiment depicted in <FIG>, the edge seal <NUM> fully covers the bus member <NUM> during subsequent manufacturing steps (such as a lamination process), thereby protecting the bus member <NUM> during subsequent manufacturing steps.

Referring now to <FIG>, the interlayer <NUM> may be added over the photovoltaic cells 200b, 200c, 200d, and a portion of the first photovoltaic cell 200a. Two regions 316a, 316b of the first photovoltaic cell 200a, on opposing sides of the insulating material <NUM>, may remain uncovered by the edge seal <NUM> and uncovered by the interlayer <NUM>. Similarly, a region <NUM> of the conductive member <NUM> and two regions 322a, 322b of the insulating material <NUM> may remain uncovered by the edge seal <NUM> and uncovered by the interlayer <NUM>. In this embodiment, the interlayer <NUM> is not used to cover the bus member <NUM> because the edge seal <NUM> covers the bus member <NUM>. Accordingly, less interlayer material may be used than if the interlayer <NUM> were to cover the bus member <NUM>.

As seen in <FIG>, the bus member <NUM> may be deposited over the conductive member <NUM> and the insulating material <NUM> in an area closer to the peripheral edge <NUM> of the photovoltaic device <NUM> than in the embodiment depicted in <FIG> (not claimed). This is because, in the embodiment depicted in <FIG> (not claimed), the bus member <NUM> (and the T-joint <NUM>) are wholly covered by the edge seal <NUM> instead of the interlayer <NUM>, and therefore the amount of interlayer material needed to cover the bus member <NUM> is not a factor for determining the positioning of the bus member <NUM>. Consequently, the first photovoltaic cell 200a may be made smaller than in the embodiment depicted in <FIG> (not claimed), because there is no need for the interlayer <NUM> to reach to the bus member <NUM>, and therefore no need to use an undesirable amount of interlayer material. Because this embodiment allows for the T-joint <NUM> to be closer to the peripheral edge <NUM> while still being covered and protected during subsequent manufacturing steps, the distance d<NUM> that the first photovoltaic cell 200a extends may be reduced so as to be closer in size to the distance d<NUM> that the second photovoltaic cell 200b extends, or the distances that the neighboring photovoltaic cells 200c, 200d extend. In this manner, overall efficiency of the photovoltaic device <NUM> may be improved.

Referring now to <FIG>, an alternative embodiment of a photovoltaic device <NUM> (not claimed) at certain sequential steps during a manufacturing process is depicted. In this embodiment, the T-joint <NUM> is covered by the edge seal <NUM>, but less edge seal material is used compared to the embodiment depicted in <FIG> (not claimed).

Referring now to <FIG>, the insulating material <NUM> may be added over the photovoltaic cells <NUM> in the same manner as before, extending over at least a portion of the first photovoltaic cell 200a. A dead area <NUM> may be created by a suitable ablation method adjacent to the peripheral edge <NUM> of the photovoltaic device <NUM>. The dead area <NUM> may extend along the length Y from the first side edge <NUM> to the second side edge <NUM>. The first photovoltaic cell 200a is adjacent to the dead area <NUM>.

Referring now to <FIG>, the conductive member <NUM> may be added over the insulating material <NUM> as previously described. The conductive member <NUM> may be positioned over at least a portion of the first photovoltaic cell 200a. The conductive member <NUM> may extend over a plurality of the photovoltaic cells <NUM>. The conductive member <NUM> may contact the dead area <NUM>. In other embodiments, the conductive member <NUM> and the dead area <NUM> do not contact one another.

Referring now to <FIG>, the bus member <NUM> may be added over the conductive member <NUM> to form a T-joint <NUM> where the bus member <NUM> overlaps the conductive member <NUM>. The bus member <NUM> may extend from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM> of the photovoltaic device <NUM>. The bus member <NUM> may have a width W that extends in its entirety over the conductive member <NUM>, and over the first photovoltaic cell 200a. The bus member <NUM> may be electrically coupled to the first photovotlaic cell 200a, and electrically coupled to the conductive member <NUM>. The bus member <NUM> may be in direct contact with the first photovoltaic cell 200a, or may alternatively be electrically coupled thereto through a conductive metal or a conductive adhesive. The bus member <NUM> may be in direct contact with the conductive member <NUM>, or may alternatively be electrically coupled thereto through a conductive adhesive.

Referring now to <FIG>, the edge seal <NUM> may be formed in a shape that includes a tab <NUM> extending over the T-joint <NUM>. The edge seal <NUM> may be disposed along or near the peripheral edge <NUM>, but need not extend all the way to the peripheral edge <NUM>. Rather, as seen in <FIG>, some of the dead area <NUM> may remain uncovered by the edge seal <NUM>. Some of the edge seal <NUM> may extend along the length Y from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM>, while the tab <NUM> does not extend along then length Y to the same extent. Rather, the tab <NUM> may have a shorter length l<NUM> compared to the length l<NUM> of the remaining edge seal <NUM>. The edge seal <NUM> may include side portions <NUM>, <NUM> which extend from the region <NUM> of the edge seal <NUM> having the longer length l<NUM> to the tab <NUM> having the shorter length l<NUM>. The side portions <NUM>, <NUM> may be angular, as seen in <FIG>, or may alternatively be substantially parallel to the first side edge <NUM> and the second side edge <NUM>.

The tab <NUM> of the edge seal <NUM> may extend to a position over the serial scribe line <NUM> separating the first photovoltaic cell 200a from the second photovoltaic cell 200b. The remaining portion of the edge seal <NUM>, between the tab <NUM> and the peripheral edge <NUM>, may cover only a portion of the first photovoltaic cell 200a. In this embodiment, the edge seal <NUM> is defined by a region <NUM> having a first length l<NUM> from the first side edge <NUM> to the side portion <NUM> which extends inwardly from the peripheral edge <NUM> to the serial scribe line <NUM>, and then the tab <NUM> having a second length l<NUM> from the side portion <NUM> over the T-joint <NUM> to the side portion <NUM>, which extends back to the region <NUM> having the first length l<NUM>. The edge seal <NUM> may have the first length l<NUM> over the dead area <NUM>, and the second length l<NUM> over the T-joint <NUM>, where the first length l<NUM> is greater than the second length l<NUM>.

Referring to <FIG>, the tab <NUM> may extend over the bus member <NUM> from the first side edge <NUM> of the insulating material <NUM> to the second side edge <NUM> of the insulating material <NUM>. In other embodiments, the tab <NUM> may extend over the bus member <NUM> from the first side edge <NUM> of the conductive member <NUM> to the second side edge <NUM> of the conductive member <NUM>. The tab <NUM> may extend over the serial scribe line <NUM>, and may extend over some portions of the first photovoltaic cell 200a to the sides of the insulating material <NUM>. However, this is not necessary.

Advantageously, as seen in <FIG>, the T-joint <NUM> may be covered by the edge seal <NUM>. However, the edge seal <NUM> does not cover the entire bus member <NUM> across the length Y of the photovoltaic device <NUM>. Rather, the bus member <NUM> remains uncovered by the edge seal <NUM>, for some portion 225a, 225b on each side of the T-joint <NUM>.

Referring now to <FIG>, the interlayer <NUM> may be added as previously described. After the interlayer <NUM> is added, the portions 225a, 225b of the bus member <NUM> may be uncovered by the interlayer <NUM>, and may therefore be uncovered by both the edge seal <NUM> and the interlayer <NUM>. Furthermore, areas of the first photovoltaic cell 200a on opposing sides of the T-joint <NUM> may also be uncovered by the edge seal <NUM> and uncovered by the interlayer <NUM>. In any event, because the bus member <NUM> is covered by the edge seal <NUM> where the bus member <NUM> overlaps the conductive member <NUM>, the T-joint <NUM> is more robust and is protected during subsequent manufacturing steps. Advantageously, this embodiment does not require as much material to form the edge seal <NUM> as the embodiment depicted in <FIG> (not claimed). This embodiment also allows for a reduced size of the first photovoltaic cell 200a, because the interlayer <NUM> is not used to cover and protect the T-joint <NUM>.

Referring now to <FIG>, an alternative embodiment of a photovoltaic device <NUM> (not claimed) at certain sequential steps of a manufacturing process is depicted. As shown in <FIG>, the insulating material <NUM> may be added over the photovoltaic cells <NUM>, and the conductive member <NUM> may be added over the insulating material <NUM>, as previously described. A dead area <NUM> may extend inwardly from the peripheral edge <NUM> of the photovoltaic device <NUM>, formed by a suitable ablation method. The insulating material <NUM> has a peripheral edge <NUM> that may be over the first photovoltaic cell 200a, and may be near the dead area <NUM>. In other embodiments, the peripheral edge <NUM> of the insulating material <NUM> may be on the dead area <NUM>. The conductive member <NUM> has a peripheral edge <NUM> that may be on the opposite side of the peripheral edge <NUM> from the dead area <NUM>, though still over the first photovoltaic cell 200a.

Referring now to <FIG>, a bridge <NUM> may be formed over the insulating material <NUM> and the conductive member <NUM>. The bridge <NUM> may cover the peripheral edge <NUM> of the conductive member <NUM>, and may extend over adjacent portions of the insulating material <NUM>. The bridge <NUM> may extend over the peripheral edge <NUM> of the insulating material <NUM>. The bridge <NUM> can be formed, for example, from a wide conductive metal with conductive adhesive and can serve to bridge the bus member <NUM> and the conductive member <NUM>. In some embodiments, the bridge <NUM> is a multilayer structure composed of one or more conductive metal layers and one or more conductive adhesive layers. In some embodiments, the bridge <NUM> is a multilayer structure composed of a liner, one or more layers of a conductive metal, and one or more layers of a conductive adhesive. In some embodiments, the bridge <NUM> is a multilayer structure composed of two or more conductive metal layers and two or more conductive adhesive layers.

Referring now to <FIG>, the bus member <NUM> may be added over the bridge <NUM>. The bus member <NUM> may extend along the length Y from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM> of the photovoltaic device <NUM>. The bus member <NUM> may have a width Wi that is completely over the first photovoltaic cell 200a. The bus member <NUM> may be electrically coupled to the first photovoltaic cell 200a, for example, by directly contacting the first photovoltaic cell 200a or through a conductive metal or a conductive adhesive. Additionally, the bus member <NUM> may be in direct contact with the bridge <NUM>. The bridge <NUM> may be disposed between the conductive member <NUM> and the bus member <NUM>. The bridge <NUM> may be configured to electrically couple the conductive member <NUM> to the bus member <NUM>. The bridge <NUM> may serve to enhance the conduction of current between the bus member <NUM> and the conductive member <NUM>.

Referring now to <FIG>, the edge seal <NUM> may be formed over the bus member <NUM> and portions of the bridge <NUM> and insulating material <NUM>. The edge seal <NUM> may cover the entire bus member <NUM>. The edge seal <NUM> may extend from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM> of the photovoltaic device <NUM>. The edge seal <NUM> may leave some of the dead area <NUM> remaining uncovered at or near the peripheral edge <NUM> of the photovoltaic device <NUM>. In alternative embodiments, the edge seal <NUM> may extend to the peripheral edge <NUM> such that no dead area <NUM> remains uncovered by the edge seal <NUM>.

Referring now to <FIG>, the interlayer <NUM> may be formed so as to leave an exposed area <NUM> of the bridge <NUM> and exposed areas 338a, 338b of the insulating material <NUM>, where such areas <NUM>, 338a, 338b are uncovered by the edge seal <NUM> and uncovered by the interlayer <NUM>. Further, the conductive member <NUM> may be partly covered by the bridge <NUM> and partly covered by the interlayer <NUM>. In this embodiment, the bus member <NUM> may be completely covered by the edge seal <NUM>, and therefore protected by the edge seal <NUM> during subsequent manufacturing steps. Thus, advantageously, this embodiment also allows for a reduced size of the first photovoltaic cell 200a because the interlayer <NUM> is not being used to protect the bus member <NUM>.

Referring now to <FIG>, an alternative embodiment (not claimed) is depicted in which the bridge <NUM> is formed over the bus member <NUM> instead of between the bus member <NUM> and the conductive member <NUM>. As seen in <FIG>, the insulating material <NUM> and then the conductive member <NUM> may be applied over the photovoltaic cells <NUM> as previously described. The insulating material <NUM> may extend over at least a portion of the first photovoltaic cell 200a. A dead area <NUM> may be formed extending inwardly from the peripheral edge <NUM> of the photovoltaic device <NUM> by a suitable ablation method.

Referring now to <FIG>, the bus member <NUM> may be applied as before, extending along the length Y over the conductive member <NUM> and over the first photovoltaic cell 200a from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM> of the photovoltaic device <NUM>. The bus member <NUM> may have a width W that is completely on top of the first photovoltaic cell 200a. The bus member <NUM> may be electrically coupled to the first photovoltaic cell 200a, for example by direct contact or via a conductive metal or a conductive adhesive. However, in this embodiment, in contrast to the embodiment depicted in <FIG> (not claimed), the bus member <NUM> is applied before the bridge <NUM>.

Referring now to <FIG>, the bridge <NUM> may be applied over the bus member <NUM>, and can be rolled into place at the peripheral edge <NUM> of the conductive member <NUM> and the peripheral edge <NUM> of the insulating material <NUM>. As in the previous embodiment, the bridge <NUM> can be formed from a wide conductive metal with a conductive adhesive, and can serve to bridge the bus member <NUM> and the conductive member <NUM>. In some embodiments, the bridge <NUM> is a multilayer structure composed of one or more conductive metal layers and one or more conductive adhesive layers. In some embodiments, the bridge <NUM> is a multilayer structure composed of a liner, one or more layers of a conductive metal, and one or more layers of a conductive adhesive. In some embodiments, the bridge <NUM> is a multilayer structure composed of two or more conductive metal layers and two or more conductive adhesive layers. In contrast to the previous embodiment, however, the bridge <NUM> may be disposed on top of the bus member <NUM> and the conductive member <NUM> such that a portion of the bus member <NUM> is disposed between the insulating material <NUM> and the bridge <NUM>, and a portion of the conductive member <NUM> is disposed between the insulating material <NUM> and the bridge <NUM>. The bus member <NUM> may not be in direct contact with the conductive member <NUM>, but is electrically coupled to the conductive member <NUM> through the bridge <NUM>. In this embodiment, the bus member <NUM> is conductive on both sides to facilitate electrical communication. That is, the bus member <NUM> may include a first surface facing the first photovoltaic cell 200a comprising a conductive material, and a second surface facing the bridge <NUM> comprising a conductive material.

Referring now to <FIG>, application of the edge seal <NUM> and the interlayer <NUM>, can be the same as previously described. The edge seal <NUM> may extend along the length Y from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM>, leaving uncovered some of the dead area <NUM> adjacent the peripheral edge <NUM> of the photovoltaic device <NUM>. Alternatively, the edge seal <NUM> may extend to the peripheral edge <NUM> such that none of the dead area <NUM> remains uncovered by the edge seal <NUM>. The edge seal <NUM> may extend along the width X so as to cover the exposed portions of the bus member <NUM> not covered by the bridge <NUM>. Thus, in this embodiment, the bridge <NUM> and the edge seal <NUM> may protect the bus member <NUM> during subsequent manufacturing steps.

The interlayer <NUM> may extend along the length Y from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM> of the photovoltaic device <NUM>. The interlayer <NUM> may cover portions of the bridge <NUM>, conductive member <NUM>, and insulating material <NUM> not covered by the edge seal <NUM>. Thus, in this embodiment, the bus member <NUM> is again completely covered by the edge seal <NUM>, and therefore protected by the edge seal <NUM> during subsequent manufacturing steps. Therefore, this embodiment advantageously allows for a reduction in the size of the first photovoltaic cell 200a, because the interlayer <NUM> is not being used to cover and protect the bus member <NUM>.

Referring now to <FIG>, an alternative embodiment of a photovoltaic device <NUM> at certain sequential stages of a manufacturing process is depicted. As shown in <FIG>, the insulating material <NUM> and then the conductive member <NUM> are added over the photovoltaic cells <NUM> as previously described. The insulating material <NUM> and the conductive member <NUM> may extend over at least a portion of the first photovoltaic cell 200a. A dead area <NUM> may be formed by a suitable ablation method adjacent to the peripheral edge <NUM> of the photovoltaic device <NUM>.

Referring now to <FIG>, a patch <NUM> is added over the insulating material <NUM> and the conductive member <NUM>. The patch <NUM> is composed of a conductive material, and may be printed onto the photovoltaic device <NUM>. However, the patch <NUM> does not need to be a printed conductor. The patch <NUM> may serve to enhance conduction of the electricity generated from the photovoltaic cells <NUM> to the bus member <NUM>.

Referring still to <FIG>, the patch <NUM> may include a top portion <NUM> and a bottom portion <NUM>. The bottom portion <NUM> may be wide enough to cover the width WC of the conductive member <NUM> but not wide enough to cover the entire width WI of the insulating material <NUM>, and the top portion <NUM> may be wide enough to extend across the first photovoltaic cell 200a for a distance greater than the entire width WI of the insulating material <NUM>. The top portion <NUM> may not cover the insulating material <NUM> or the conductive member <NUM>. The bottom portion <NUM> may cover a segment of the conductive member <NUM> for the entire width WC of the the conductive member <NUM>, as well as surrounding areas of the insulating material <NUM>. The patch <NUM> may cover the peripheral edge <NUM> of the insulating material <NUM> and the peripheral edge <NUM> of the conductive member <NUM>, and the top portion <NUM> may extend beyond the peripheral edge <NUM> of the insulating material <NUM> toward the dead area <NUM>, as well as toward the first side edge <NUM> of the photovoltaic device <NUM> and/or the second side edge <NUM> of the photovoltaic device <NUM>.

Referring now to <FIG>, the bus member <NUM> may be added across the top portion <NUM> of the patch <NUM>, extending along the length Y from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM> of the photovoltaic device <NUM>. The bus member <NUM> may have a width W that is completely over the first photovoltaic cell 200a. The bus member <NUM> is electrically coupled to the first photovoltaic cell 200a, for example by direct contact or through a conductive metal or a conductive adhesive. The bus member <NUM> is electrically coupled to the conductive member <NUM> through the patch <NUM>.

Referring now to <FIG>, the edge seal <NUM> is added and the interlayer <NUM> may be added as previously described, extending along the length Y from a location near a dead area at the first side edge <NUM> to a location near a dead area at the second side edge <NUM> of the photovoltaic device <NUM>. The edge seal <NUM> may completely cover the bus member <NUM>, and therefore protect the bus member <NUM> during subsequent manufacturing steps. Areas 348a, 348b of the insulating material <NUM> on respective sides of the patch <NUM>, and an area <NUM> of the patch <NUM>, may remain uncovered by the edge seal <NUM> and uncovered by the interlayer <NUM>. However, the bus member <NUM> may be completely covered by the edge seal <NUM>. Therefore, this embodiment also allows for a reduction in the size of the first photovoltaic cell 200a, because the interlayer <NUM> is not being used to cover and protect the bus member <NUM> during subsequent manufacturing steps. Furthermore, the patch <NUM> may enhance the electrical conduction from the photovoltaic cells <NUM> through the bus member <NUM> to the conductive member <NUM> while also providing robustness to the bus member <NUM>.

Advantageously, the photovoltaic devices <NUM> described herein may have bussing configurations that reduce dead area loss from end cells to nearly zero, thereby improving device efficiency. Furthermore, the photovoltaic devices <NUM> described herein may have bussing configurations that provide for low and stable contact resistance at the T-joint <NUM>, which is important for good device performance.

The bussing components described herein, such as the insulating material <NUM>, conductive member <NUM>, bridge <NUM>, patch <NUM>, edge seal <NUM>, and interlayer <NUM>, may each be deposited by any suitable method, and may be sequentially added in a conveyored system using one or more stations or chambers. Some components, such as the patch <NUM>, may be printed onto the photovoltaic device <NUM>. However, the patch <NUM> need not be printed, and may be applied through other methods.

According to embodiments described herein, a photovoltaic device may include a bus member that is fully covered under an edge seal. The edge seal may protect the bus member during certain manufacturing steps. According to embodiments described herein, a photovoltaic device may include a bus member overlapping a conductive member to define a T-joint, where the T-joint is fully covered under an edge seal. However, in some embodiments, at least a portion of the bus member is not covered by the edge seal, while the portion of the bus member overlapping the conductive member (i.e., the T-joint) is covered by the edge seal. For example, in some embodiments, two portions of the bus member, on opposing sides of the T-joint, are not covered by the edge seal. By "covered" it is meant that the bus member, or a portion thereof, is disposed between the edge seal and the photovoltaic cells.

According to embodiments described herein, a photovoltaic device may include a patch of a conductive material that overcomes tolerance and improves robustness of a T-joint defined by the overlap of a bus member over a conductive member.

According to embodiments described herein without being claimed, a photovoltaic device may include a bridge composed of a conductive metal and a conductive adhesive that electrically couples a bus member to a conductive member. According to embodiments described herein, the bridge may be a multilayer structure composed of two or more layers of the conductive metal and two or more layers of the conductive adhesive. According to embodiments described herein, the bridge may be a multilayer structure composed of one or more conductive metal layers and one or more conductive adhesive layers. According to embodiments described herein, the bridge may be a multilayer structure composed of a liner, one or more layers of a conductive metal, and one or more layers of a conductive adhesive.

According to embodiments described herein without being claimed, a photovoltaic device having a bus member that is disposed between an edge seal and a plurality of photovoltaic cells may further include a bridge comprising a conductive adhesive that electrically couples the bus member to a conductive member. In certain embodiments, the bridge is disposed between an insulating material and the bus member. In certain embodiments, the bridge is disposed between the bus member and the edge seal.

According to embodiments described herein, a photovoltaic device having a bus member that is disposed between an edge seal and a plurality of photovoltaic cells may further include a conductive patch disposed between a conductive member and the bus member.

According to embodiments described herein, a photovoltaic device having a bridge (not claimed) or a patch as described herein may also have a bus member that is not fully covered by an edge seal. Rather, the bus member may include one or more portions that are not disposed between the edge seal and the photovoltaic cells.

According to embodiments described herein, a photovoltaic device having a bridge (not claimed) or a patch as described herein may also have an edge seal with a first length and a second length, where the first length and the second length are different, and side portions connecting edge seal material of the first length and edge seal material of the second length.

According to embodiments described herein, a photovoltaic device having a bridge (not claimed) or a patch as described herein may also include an edge seal that is disposed over a T-joint defined by the overlap of a bus member over a conductive member, and is not disposed over at least a portion of the bus member. In alternative embodiments, the edge seal is disposed over the entire bus member.

According to embodiments described herein, a photovoltaic device may have a bus member composed of a multilayer structure comprising a liner, a metal, and a conductive adhesive. Such a bus member may be employed in a photovoltaic device having a patch or a bridge (not claimed) as described herein. Such a bus member may also be employed in a photovoltaic device having an edge seal that covers some or all of the bus member.

According to embodiments described herein, a photovoltaic device may include an edge seal having a first length over a dead area, and a second length over a T-joint defined by the overlap of a bus member over a conductive member, where the first length is greater than the second length. In some embodiments, the bus member of such a photovoltaic device comprises two portions that are uncovered by the edge seal. In some embodiments described herein without being claimed, the photovoltaic device further comprises a bridge as described herein. The photovoltaic device of the present invention further comprises a patch as described herein.

Claim 1:
A photovoltaic device (<NUM>, <NUM>) comprising:
a plurality of electrically connected photovoltaic cells (<NUM>), wherein the photovoltaic cells (<NUM>) comprise a conducting layer (<NUM>) having a first surface (<NUM>) and a second surface (<NUM>), the first surface (<NUM>) facing an absorber layer (<NUM>);
an insulating material (<NUM>) disposed on the second surface (<NUM>) over at least one of the photovoltaic cells (<NUM>);
a conductive member (<NUM>) on the insulating material (<NUM>), wherein the insulating material (<NUM>) is configured to electrically insulate the conductive member (<NUM>) from the second surface (<NUM>);
a bus member (<NUM>), wherein the bus member (<NUM>) is electrically coupled to the one of the plurality of photovoltaic cells (<NUM>); and
an edge seal (<NUM>) comprising a sealant material extending over at least a portion of the one of the plurality of photovoltaic cells (<NUM>);
characterized in that:
the photovoltaic device (<NUM>, <NUM>) further comprises a patch (<NUM>) comprising a conductive material on a peripheral edge (<NUM>) of the conductive member (<NUM>) and a peripheral edge (<NUM>) of the insulating material (<NUM>);
wherein the bus member (<NUM>) is over the one of the plurality of photovoltaic cells (<NUM>) and the patch (<NUM>), and is disposed between the edge seal (<NUM>) and the patch (<NUM>); and
wherein the patch (<NUM>) electrically couples the bus member (<NUM>) to the conductive member (<NUM>).