DE112012002511T5 - Photovoltaic system and connector for a photovoltaic cell with interlocking contacts - Google Patents

Abstract

A photovoltaic system comprises a semiconductor substrate with a surface with interlocking first and second contact areas, which provide contact with emitter and base contact areas in or on the semiconductor. A connecting strand comprises a conductor track and electrically insulating material in rings around the conductor track. Parts of the interconnect between the rings are connected to several of the first contact areas, in electrical contact with the first contact areas, with electrically insulating material from the rings between the interconnect and the second contact areas.

Description

The invention relates to a photovoltaic system having interdigitated back contact (IBC) technology, a connector suitable for use as an electrically conductive connector for electrical contact areas in a photovoltaic system, a connector assembly, and a method of making a connector.

Photovoltaic cells are semiconducting devices designed to convert photons into electrical energy. Well known is their use as solar collectors, such as according to US 4,234,352 , Generally, the photovoltaic cell comprises a semiconductive material that serves as a photoactive material in which light energy (photons) is converted into excited mobile carriers. The semiconductive material typically has a pn junction defined therein. In a planar cell, the pn junction is usually formed near a surface of the semiconductive material. Conductors on p and n regions on the surface of the semiconductive material form contacts (also contact areas) for outputting current from the cell: the contacts form the cell's electrical output poles.

IBCs have interdigitated contacts of opposite polarity (emitter and base contacts) on the back surface of the cell (the surface facing away from the light source in use) and are well known. Such cells are for example in US 2008/0210301 and in WO 2009/092426 described. IBC cells have numerous advantages over conventional photovoltaic cells with front metal gratings and wall or lattice metallized contacts, including improved photo generation by eliminating front lattice shading, significantly reduced lattice series resistance, and improved "blue" photoreactivity, since heavy front surface doping is not required. to minimize the front contact resistance and because there are no front contacts. In addition to the performance benefits, the back contact cell structure allows for simplified module assembly due to co-planar contacts.

A commonly used method for connecting contact areas of a photovoltaic cell is to provide bus bars (wider conductor regions) at the ends of the contact areas. Interconnection of multiple photovoltaic cells is accomplished by providing busbars along multiple cells. A first bus bar of the cell connects first multiple contact areas (digits) forming a comb-like structure, the digits forming the teeth of the comb and the structure serving as the base contact in use. A mirror-image emitter base contact is formed by a second plurality of contact areas connected by a second bus bar provided on the same surface of the cell as the base contact. The digits of the base and emitter contacts are alternately provided on the surface, with the individual base digits of a cell normally being arranged adjacent to two emitter digits, and vice versa. This design is therefore referred to as IBD (interdigitated back contact) design.

A disadvantage of this design is a significant loss of efficiency with increasing cell size, especially when providing cells with a diameter of about 15 cm or more.

Furthermore, a dielectric layer is generally provided on the photoactive material. Localized openings are provided in this dielectric layer (serving as insulator). Metal is deposited and metal in the openings establishes electrical contact between the contacts and the photoactive material. As a result, much of the backside is covered with metal. This is disadvantageous because it increases costs and places additional demands on the insulating properties of the dielectric layer because substantially the entire cell is exposed to an electrical potential across the dielectric layer.

WO 2006/123938 discloses a photovoltaic cell having connections by means of external conductors connected to contact areas on the semiconductor body. A conductor with an insulating layer is disclosed for this purpose. The document discloses that breaks or openings in the insulating layer may be provided to allow contact with the semiconductor. However, if the connection strands are fed to the photovoltaic cell in a manner that does not prevent twisting of the strands, for example from a spindle, it can not be guaranteed that the openings will be directed towards the photovoltaic cell.

US 2010/0024881 discloses a photovoltaic cell with various connections by means of external conductors connected to contact areas on the semiconductor body. This includes films on which the conductors are applied, with overlying insulation material at locations where there is a risk of short circuit to the "wrong" areas.

US2009 / 0025788 discloses a photovoltaic cell with external guide wires connected to contact areas on the semiconductor body. Insulating material is provided on the semiconductor body to insulate the wires from the "wrong" contacts.

Summary

Among other things, an object is to provide a photovoltaic cell and a method of manufacturing such a cell, wherein external traces are used, in which the risk of short circuit is reduced.

A manufacturing method of a photovoltaic cell system according to claim 1 is provided.

By using rings of electrically insulating material on the trace, manufacturing is facilitated and short circuits can be prevented even if the orientation of the trace varies due to twisting (rotation about the length of the trace), for example, if the trace is circular or substantially circular having circular cross-section.

In one embodiment, the connection string is fed directly or indirectly from the spindle to the semiconductor substrate. Although this provides an easy way to feed the strand, it can lead to twisting. The use of rings makes it possible to avoid the adverse effects of twisting. Another example where twisting may occur is in a process where one or more strands are stretched prior to attachment to the substrate, whether or not they are fed from a spindle.

In one embodiment, multiple connection strands may be used. With a large number of strands, the risk of shorting could increase due to torsion, but with the help of the rings this is avoided.

In one embodiment, solder material is provided on the trace. This facilitates the connection. In one embodiment, the solder material is applied after the rings of insulating material have been applied. This saves solder and prevents solder from being on the trace where it could cause a short circuit. In one embodiment, the solder material is provided on the interconnect of the interconnect or each interconnect in further rings around the interconnect. Thus, twisting can not lead to sections of the conductor track without soldering material lying opposite contact areas with which they are to be connected.

In other embodiments, a fusible metal alloy may be used as the solder material. Alternatively, other materials, for example a paste-like medium comprising conductive granules, may be used. In one embodiment, the granules may be sintered during soldering. In another embodiment, the solder material or medium may be provided on the substrate instead of additionally on the connecting strand.

In one embodiment, the photovoltaic cell is temporarily held in a bent state when the trace is connected to the first contacts of the photovoltaic cell, wherein the surface of the photovoltaic cell on which the trace is connected, in the bent state, a convex Curvature has. This reduces stresses for later use.

• – einem Halbleitersubstrat mit einer Oberfläche mit ineinander greifenden (interdigitated) ersten und zweiten Kontaktbereichen, die jeweils für Kontakt zu Emitter- und Basis-Kontaktbereichen in oder auf dem Halbleiter bzw. zu Basis- und Emitter-Kontaktbereichen in oder auf dem Halbleiter sorgen,
• – einem Verbindungsstrang, umfassend eine Leiterbahn und elektrisch isolierendes Material in Ringen um die Leiterbahn herum, mit verbindenden Teilen der Leiterbahn zwischen den Ringen verbunden mit mehreren der ersten Kontaktbereiche, in elektrischem Kontakt mit den ersten Kontaktbereichen, mit elektrisch isolierendem Material von den Ringen zwischen der Leiterbahn und den zweiten Kontaktbereichen, wobei der Verbindungsstrang über das Halbleitersubstrat hinaus verläuft.

A photovoltaic cell system is provided with

• A semiconductor substrate having a surface with interdigitated first and second contact regions each providing contact to emitter and base contact regions in or on the semiconductor, and to base and emitter contact regions in or on the semiconductor,
• A connecting strand comprising a conductor track and electrically insulating material in rings around the track, with connecting parts of the track between the rings connected to a plurality of the first contact areas, in electrical contact with the first contact areas, with electrically insulating material from the rings between the track Conductor and the second contact regions, wherein the connecting strand extends beyond the semiconductor substrate.

Short description of the drawing

These and other objects and advantageous aspects will become apparent from exemplary embodiments illustrated in the following figures.

1 . 1a shows a connection string

2a , b show a photovoltaic cell with a connector

3 shows a group of photovoltaic cells

4 shows a photovoltaic cell with a connector

5 Figure 1 shows a strand making arrangement

6 shows an assembly manufacturing arrangement

7 shows a woven connector

Detailed description of exemplary embodiments

1 shows a cross section of a connecting strand for connecting to contact areas of a photovoltaic cell. The connecting string (not to scale) comprises an elongated metal core 10 , insulating windings in the form of rings 12 of electrically insulating material on core 10 at successive positions in the axial direction 16 from core 10 , separated by solder rings 14 made of soldering material. In the cross section, each insulating ring 12 and every solder ring 14 shown as two regions, but it is understood that each insulating ring 12 and every solder ring 14 around core 10 can run continuously in a circulating path.

1a shows a cross section of an alternative connection string for connecting to contact areas of a photovoltaic cell. In this embodiment, the windings are part of strand 18a -F made of electrically insulating material, running obliquely around the metal core 10 , (As is known, "oblique" means in a curve corresponding to a helix or spirally around the core, but as used herein, "obliquely about" means the relative positions of metal core 10 and the strand, ie, the strand spirals around the core even though the core is skewed around the strand). The figure shows successive cross sections 18a -F through this strand: the insulating strand runs from cross section 18a to cross section 18b and from there to cross section 18c and so on. metal core 10 is with a layer 19 made of soldering material. Although one embodiment is shown in the metal core 10 is straight and the strand of insulating material is wound around it, it is to recognize that the metal core 10 and the string of insulating material may be a coiled pair of wires so that each may be referred to as running at an angle to the other. On the other hand, the string of insulating material could be straight while the metal core 10 turns around him. As used here, the strand of insulating material is also in this case obliquely around the metal core 10 to run.

Although disruptions in the form of helical (helical) windings provide an easy way of making contact, it should be noted that this makes the manufacturing process susceptible to failure in the case of twisting of the connecting strands. Twist could result in isolation from the intended contact or electrical contact with a contact to be kept isolated from the connection string.

2a FIG. 12 is a view of a portion of a back surface of a photovoltaic cell (not to scale) comprising a set of base contact regions. FIG 22 in the form of metal fingers that run parallel to each other and a set of emitter contact areas 24 in the form of metal fingers that are parallel to each other and to the metal fingers of the base contact areas 22 run. Base contact areas 22 and emitter contact areas 24 alternate along a direction across the fingers, with an emitter contact area 24 between each pair of successive parallel base contact areas 22 is provided.

A first and second linkage 26 . 28 are on the back surface 20 , extending transversely to the fingers, provided. A first link 26 is positioned so that portions of its insulating windings between the metal core and the substrate over the emitter contact areas 24 are arranged. If rings of insulating material are used, the first connecting strand 26 be positioned so that its insulating rings (marked by hatching) over the emitter contact areas 24 are arranged and its Lötkontaktringe over the base contact areas 22 are arranged. A second connection string 26 is positioned so that portions of its insulating windings between the metal core and the substrate over the base contact areas 24 are arranged. If rings of insulating material are used, the second connecting strand may be used 28 be positioned so that its insulating rings over the base contact areas 22 are arranged and its Lötkontaktringe over the emitter contact areas 24 are arranged.

2 B shows a cross-section of a portion of the photovoltaic cell through a virtual plane through the axis of the first linkage 26 for the embodiment with rings. The virtual plane intersects the base contact areas 22 and emitter contact areas 24 perpendicular to its axial direction. Part of the insulating rings 12 lies between the metal core 10 of the first link 26 and the emitter contact areas 24 , solder rings 14 connect the metal core 10 of the first link 26 with the basic contact areas 22 ,

Also known per se, the photovoltaic cell may comprise a semiconductor substrate of a first conductivity type (n-type for example) having regions of a second conductivity type (p-type for example) on its surface (as used herein, "on" refers to both A layer of the second conductivity deposited on the semiconductor substrate and on a layer formed by adding doping in the semiconductor substrate adjacent to its surface Each region of the second conductivity type forms an emitter region coupled to the semiconductor body via a semiconductor compound interlocking back Contact cell, the regions of the second conductivity type are pattern-provided on the semiconductor, alternating with regions of the first conductivity type (preferably with improved doping to the semiconductor substrate). Each region of the first conductivity type forms a base region coupled to the semiconductor substrate without an intervening semiconductor compound. Base and emitter contact areas 22 . 24 are formed by a conductor (comprising sintered metal granules or coated or vaporized material) in contact with the base and emitter regions, respectively. Other layers may be present, such as an insulating layer on the back surface, a reflective layer, etc. The contact between the contact regions and the base and emitter regions may be provided by such layers.

For the sake of clarity, only the contact areas 22 . 24 shown in the figures. The semiconductor body, the base region and the emitter regions are and other layers are not shown in the figures. The first and second links 26 . 28 are used to form such conductors of base and emitter contact areas, respectively 22 . 24 connect to.

During manufacture, a connecting strand and the semiconductor substrate are processed separately, after which the connecting strand is connected to the semiconductor substrate. That is, on the one hand becomes the connecting strand with its elongated metal core 10 , insulating rings 12 and solder rings 14 and on the other hand, the semiconductor substrate having emitter and base regions and the first and second contact regions 22 . 28 produced. An interconnect of any length may be produced, which is subsequently cut into sections which are connected to the semiconductor substrate (before or after cutting). The connection string may be bonded to the semiconductor substrate by heating at a temperature high enough to solder the solder rings 14 to be liquefied.

Although an embodiment is shown in which the solder material is part of the interconnect strand provided on metal core 10 before connecting the connection string to the semiconductor substrate, it must be recognized that this is not absolutely necessary. Alternatively, the soldering material may be applied to the semiconductor substrate, wherein a metal core with or without soldering material is bonded to the semiconductor substrate by means of the soldering material on the semiconductor substrate. As another alternative, the solder material may be applied to the metal core during assembly. The solder material does not have to be in a ring around the entire perimeter of the metal core 10 it may be sufficient to apply soldering material in one place on a part of the circumference, for example one half or one quarter of the circumference. Similarly, the insulating material need not be provided in rings: it could cover a part of the circumference and / or it could run on part of the circumference at the axial position where the solder material is provided. But this might require controlling the twist of the connecting string during assembly. metal core 10 may have a circular cross-section. But alternatively, metal core 10 be strip-shaped. metal core 10 may have any cross section, for example an elliptical cross section with a major axis that is longer than its minor axis. A flattened cross-section can facilitate control of twisting during assembly.

contact areas 22 and emitter contact areas 24 may be provided in a periodically repeating pattern as viewed in a direction transverse to the direction of the fingers. In a similar way, insulating rings can 12 and solder rings 14 be provided on the connection string in a periodically repeating pattern in this direction. The period lengths of the patterns of the contact areas and the connection string may be substantially the same, that is, not so different that there may be no contact or insulation from a contact area at one end of the connection of the connection string on a photovoltaic cell, if a contact or a Insulation at the opposite end of the connecting strand on the photovoltaic cell consists. The bonding wire may extend in a direction perpendicular to the direction of the fingers, in which case the period length of the contacts along that direction may be substantially the same as the period length of the bonding wire. But the connecting wire can run in a different direction across the fingers, z. At an angle that deviates from ninety degrees in a direction perpendicular to the direction of the fingers. In this case, the period length of the contacts along the transverse direction may be substantially the same as the period length of the connection wire. However, any pattern of spaces between the contacts may be used, not necessarily a periodic pattern, and / or the bond wire may not necessarily be provided along a straight line. In this case, the pattern of the distances between the rings on the connecting wire need not be periodic. But a periodic pattern with straight bond wires simplifies manufacturing, and perpendicular angles minimize material costs.

3 shows an arrangement of photovoltaic cells, comprising a first, second and third photovoltaic cell 30a -D, connected in series connecting string 32a , b, 34a , b. In the arrangement are first, second and third photovoltaic cells 30a -C mounted in a row on a support structure (not shown), with the base and emitter contact areas of the first, second and third photovoltaic cells 30a -C parallel to each other and transverse to the row direction, in the first, second and third photovoltaic cells 30a -C follow each other along the row.

A first link 32a passes over the first and second photovoltaic cell 30a , b, but not to the third photovoltaic cell 30c , on the back surface of the first and second photovoltaic cell 30a , b. Gradient in the transverse direction to the fingers. The first link 32a is positioned so that its insulating rings over the emitter contact areas of the first photovoltaic cell 30a are arranged and its Lötkontaktringe over the base contact areas of the first photovoltaic cell 30a are arranged. The first link 32a is positioned so that its insulating rings over the base contact areas of the second photovoltaic cell 30b are arranged and its Lötkontaktringe over the emitter contact areas of the second photovoltaic cell 30b are arranged. So connects the first link 32a the first and second photovoltaic cell 30a , b in series.

A second connection string 32b runs over the second and third photovoltaic cell 30b , c, but not the first photovoltaic cell 30a , on the back surface of the second and third photovoltaic cell 30b , c. The second link 32b is similar to the first and second photovoltaic cells 30a , b connected as the first link 32a with the first and second photovoltaic cell 30a , b is connected. So connect the first and second link 32a , b together the first, second and third photovoltaic cell 30a -C in series.

In the example of 3 run third and fourth connecting strands 34a , b, 34a , b only in each case via the first and third photovoltaic cell 30a , c, electrically connected to the emitter contact regions of the first photovoltaic cell 30a or the base contact areas of the third photovoltaic cell 30c , However, it is understood that more than three photovoltaic cells can be placed and connected in series, and in this case, third and / or fourth connection strands may be the same as the first and second connection strands 32a , b, connecting the first and third photovoltaic cell 30a , c in series with adjacent photovoltaic cells (not shown), if any.

Preferably have connecting strands 32a , b a yielding part at the junctions between the photovoltaic cell 30a -C, for example in the form of a loop or partial loop. This can be prevented by the relative movement of the photovoltaic cell 30a -C voltage arises. By applying a curvature in joining that is opposite to the curvature after shrinking, the cell remains flat.

Although examples are shown with two connection strings connected to each photovoltaic cell, it must be recognized that only one connection string is used to contact one of the base and / or emitter contact regions 22 . 24 can be used while the other is connected by a conventional bus bar. Although examples are shown with only two interconnects connected to each photovoltaic cell, the use of a large number of interconnect strands is preferred, for example, at least ten are used for a photovoltaic cell, connected in parallel and spaced apart in the direction of the fingers.

4 shows such an arrangement with several first connecting strands 40 at a uniform distance from each other and a plurality of second connecting strands 42 , evenly spaced from each other. Every first link 40 is off, as for the first link 2a , b described, connected. Every second connection string 42 is off as for the second link 2a , b described, connected. The use of parallel strands offers the advantage that the base and / or emitter contact areas 22 . 24 can be made narrower or less thick without severe power loss, so that material used in the base and / or emitter contact areas 22 . 24 , can be saved. As can be appreciated, this is achieved in part if multiple tie strands are used to contact only one of the base and / or emitter contact regions 22 . 24 be used.

Although the foregoing examples of the embodiment are described with rings, it should be appreciated that similar connections with windings forming parts of a strand spirally extending around the metal core are feasible.

5 shows an exemplary arrangement for producing a connecting strand, comprising a first and second spindle 50 . 52 , a series of baths 54a -C and a UV light source 56 , The fabrication of a single interconnect strand from a single metal wire 58 , which forms the core of the connection string, will be described, but it must be appreciated that multiple connection strings can be made in parallel from multiple parallel wires. In operation, metal wire 58 (eg a wire made of Cu or Al) on the first spindle 50 provided. In the first bath 52a There is a liquid containing UV-polymerizable monomers. From the first spindle 50 becomes the metal wire 58 through a first bath 52a passed over one or more guide wheels. In the first bath 52a becomes a liquid film on the metal wire 58 educated. From the first bath 52a becomes the metal wire 58 at the UV light source 56 passed along.

The UV light source 56 illuminates the film on the metal wire 58 in an axially periodic pattern (here the axial direction is considered the longitudinal direction of metal wire 58 taken). In one embodiment, the interval (the period length) of this pattern corresponds to the interval of base contact areas 22 and emitter contact areas 24 the photovoltaic cell for which the connection string is used. For example, a shutter can be used, or a movable grid, which can be used with the metal wire 58 over part of the way of metal wire 58 is moved where the metal wire 58 along the UV light source 56 is directed. In one embodiment, the UV light source is 56 configured the film around the whole perimeter of metal wire 58 at the axial positions where the film is illuminated. This will cause the film to wriggle around the metal wire 58 polymerized at selected axial positions. But if no rings are used, the UV light source can 56 only illuminate part of the circumference. For example, if the metal core of the connecting strand is strip-shaped, only one side can be exposed in a periodic pattern.

From the UV source 56 becomes the metal wire 58 through a second bath 54b directed. The second bath 54b contains a solvent for removing unpolymerized monomers of the film on the metal wire 58 , From the second bath 54b becomes the metal wire 58 through a third bath 54c directed. The third bath 54c can be a galvanic bath, in which a voltage between the metal wire 58 and an electrode in the bath is applied to exposed rings of metal wire 58 to coat with soldering material. Thus, a connection string is formed comprising the metal wire 58 as a metal core, rings of polymer as rings of insulating material and rings of soldering material. From the third bath 54c becomes the connecting strand around the second spindle 52 wound, for later use for connecting base and / or emitter contacts.

Although a method of connecting the strand has been described as an example, it must be recognized that many alternatives are possible. For example, instead of axial periodic polymerization, a metal wire having a continuous insulating layer selectively removed in successive rings along the metal wire by, for example, local heating or machining may be used. As another example, a bath of liquid solder may be used to apply the solder on the metal wire in rings where no insulator material is present. As another example, solder material may be first applied to the metal wire, and the insulating material may be added later, with the insulating material removed in successive rings or selectively applied only in successive rings.

The embodiment with windings forming part of a strand spirally running around the metal core can be made by providing a separate strand and metal core (with a solder layer thereon) and wrapping the strand and metal core against each other. Alternatively, this embodiment can be easily manufactured, for example, by rotating the UV light source 56 around the metal wire 58 during illumination, instead of using an aperture, with a revolution period equal to the aperture period. Instead of a rotating light source, a plurality of light sources activated in a rotating pattern may be used, or a rotation mirror may be used to direct light in a rotating pattern on the metal wire.

6 shows an exemplary manufacturing arrangement for attaching a connecting strand 60 on photovoltaic cells 62 , The manufacturing arrangement for attaching the connecting strand comprises a conveyor belt 64 with convex curved absorbent pads 65 , a spindle 66 , a role 67 and a cutting knife 68 , In the production are photovoltaic cells 62 from the conveyor belt 64 transported to the suction pad 65 by suction through the suction pads 65 clamped. Although the procedure for a number of photovoltaic cells 62 with a photovoltaic cell 62 on each successive absorbent pad 65 on the conveyor belt 64 is described, it must be clear that several photovoltaic cells in parallel on each absorbent pad 65 can be provided, allowing multiple rows of photovoltaic cells 62 can be processed in parallel.

Several connecting strands 60 (only one shown) are parallel on spindle 66 provided helically. From spindle 66 become the connecting strands 60 between a photovoltaic cell 62 on one of the suction pads 65 and role 67 directed. Base and emitter connection strands, ie, connection strands 60 to make the electrical contact to base contacts or emitter contacts are offset between the positions of the rings of solder material passed. role 67 is against the photovoltaic cell 62 pressed with intermediate connecting strands. The supply of connecting strands 60 from spindle 66 is with the position of photovoltaic cell 62 that against role 67 suppressed, synchronized so that the solder material from the base and emitter interconnects make electrical contact to the photovoltaic cell emitter contacts 62 and insulating material on the base and emitter interconnects becomes between the core of the strand and the emitter or base contacts of the photovoltaic cell 62 placed.

role 67 can be heated to the solder material on connecting strand 60 to make fluent. The soldering material may after passing under roll 67 cooling down. Then removed cutting knife 68 a part of the connection string 60 , For a first part of the connection string 60 , which makes electrical contact with the base contacts, guides the cutting blade 68 this between successive pairs of photovoltaic cells 62 out so that the connecting string between the photovoltaic cells 62 keeps running in each pair. For a second part of the connection string 60 , which makes electrical contact with the base contacts, guides the cutting blade 68 this between successive photovoltaic cells 62 in a couple, but not between the couples. So every time becomes a continuous section of connection string 60 on two adjacent photovoltaic cells 62 attached. At the end of a series of photovoltaic cells 62 can the connection string 60 on just one photovoltaic cell 62 be attached.

The use of convex curved absorbent pads 65 when fastening connecting strands 60 offers the advantage that a certain amount of relaxation arises when the photovoltaic cells 62 from the absorbent pads 65 be solved. This reduces voltage in the photovoltaic cells 62 ,

Although one way of using the link string has been described as an example, it must be recognized that many alternatives are possible. For example, in one embodiment, parallel tie strands are first attached to a flexible foil (eg, by adhesive or heating), and then the foil is attached to the photovoltaic cells with the parallel tie strands. This facilitates alignment.

7 shows a woven connector mat comprising electrically conductive connecting strands 70a , b and electrically insulating insulator strands 72a , b as a chain and shot. Electrically conductive connecting strands 70a , b run parallel to each other. Each electrically conductive connection string 70a , b comprises a metal core covered by a solder layer. Alternate connection strands 70a . 70b For contacting base and emitter contacts, a distinction can be made. Insulator strings 72a , b run parallel to each other. Alternate insulator strands 72a . 72b to isolate base and emitter contacts can be distinguished. Each insulator strand 72a , b runs transversely to electrically conductive connecting strands 70a , b and passes alternately above and below successive electrically conductive connecting strands 70a , b. Insulator strings 72b for isolating emitter contacts pass over first of the connection strings 70a (for contacting base contacts) and under first of the connection strands 70b (for contacting emitter contacts). The next insulator strand 72a to contact emitter contacts happens conversely under and over the first and second of the connecting strands 70a , b.

In a photovoltaic cell, the connector can be mounted on the back surface, with insulator strands 72a . 72b for isolating base and emitter contacts across the base and emitter fingers and interconnects 70a . 70b for contacting base and emitter contacts connected to base and emitter contacts, respectively. The conductor mat can be made by weaving. The photovoltaic cell can be assembled by attaching the woven mat on the back surface, with insulator strands 72a . 72b aligned to base and emitter fingers, followed by heating to connect connecting strands 70a . 70b , The woven mat can be made using a manufacturing arrangement similar to that of 6 wherein the mat is fed from a spindle and pressed against the photovoltaic cell, for example when the cell is held in a curved surface. As with the tie strings with rings or patches, strands of circular or flattened cross-section can be used. Flattened insulator strands 72a . 72b offer the advantage that they are easier to keep in alignment with contact areas. Flattened connecting strands 70a . 70b have the advantage of providing wider connections to the contact areas. Just like a bond string with rings or patches of insulating material, the solder material could be on connecting strands 70a . 70b be omitted, for example, when solder material is provided on the contacts of the cell. connecting strands 70a for the base contacts may be replaced in the mat by other strands, if the connections to the base contacts are otherwise provided on the semiconductor substrate. Conversely, connecting strands can 70b for the emitter contacts in the mat are replaced by other strands when the connections to the emitter contacts are otherwise provided on the semiconductor substrate. Thus, in some embodiments, only one set of connection strings may be used.

As can be appreciated, both the woven mat and the strands with insulator rings or patches allowed attachment of one or more prefabricated strands against the back surface of a photovoltaic cell to connect to at least one set of multiple contact areas on a photovoltaic cell provide. This strand provides a common connection to the plurality of contact areas on the semiconductor substrate, for example to at least three individual contact areas, when no applied electrical conductors are available on the semiconductor substrate connecting these contact areas. Insulator material is placed between the electrical conductor of the strand and the contact areas of the other set. This insulator material may be provided in the form of patches or rings on the electrical conductor or in a woven mat.

• – Bereitstellen einer Leiterbahn;
• – Verbinden der Leiterbahn mit mehreren der ersten Kontaktbereiche, in elektrischem Kontakt mit den ersten Kontaktbereichen;
• – Bereitstellen von elektrisch isolierendem Material zwischen der Leiterbahn und den zweiten Kontaktbereichen.

A method of manufacturing a photovoltaic cell system is used, the system comprising a semiconductor substrate having a surface with interdigitated first and second contact regions suitable for contact to emitter and base contact regions in the semiconductor Base and emitter contact regions in or on the semiconductor, which method comprises:

• - Providing a conductor track;
• - connecting the conductor track to a plurality of the first contact regions, in electrical contact with the first contact regions;
• - Providing electrically insulating material between the conductor track and the second contact areas.

This provides a novel photovoltaic cell system and method of making such a system that can serve as an alternative to known photovoltaic cells, particularly a cell which overcomes one or more of the disadvantages described in the Background section.

So a trace is used, which is prefabricated, before it is connected to contacts on the photovoltaic cell. In one embodiment, such traces are provided in electrical contact with emitter contacts. However, in another embodiment, only one trace or traces of this type may be used for the base contacts to connect individual base contacts on the photovoltaic cell, or only for the emitter contacts to provide individual emitter contacts on the photovoltaic cell Photovoltaic cell to connect, while the remaining contacts are connected by a conventional busbar or busbars.

Using a trace or traces reduces or even eliminates the need to print or otherwise apply conductor material to form a bus bar with its disadvantages for at least either the base or the emitter. The system may include one or more photovoltaic cells. The photovoltaic cell or cells of the system may not have an electrical conductor on the semiconductor structure that forms an electrical connection between base contact fingers and / or between emitter contact fingers.

• – das Bereitstellen mehrerer Leiterbahnen;
• – das Verbinden der mehreren Leiterbahnen jeweils mit den mehreren der ersten Kontaktbereiche, wobei die Leiterbahnen in parallelem elektrischen Kontakt mit den ersten Kontaktbereichen verbunden werden;
• – das Bereitstellen von elektrisch isolierendem Material zwischen den Leiterbahnen und den zweiten Kontaktbereichen.

In an embodiment, the method comprises

• - Providing multiple tracks;
• - connecting the plurality of interconnects to each of the plurality of first contact regions, the interconnects being connected in parallel electrical contact with the first contact regions;
• - Providing electrically insulating material between the conductor tracks and the second contact areas.

• – das Bereitstellen einer weiteren Leiterbahn oder Leiterbahnen;
• – das Verbinden der weiteren Leiterbahn mit mehreren der zweiten Kontaktbereiche oder der weiteren Leiterbahnen mit jeweils mehreren der zweiten Kontaktflächen;
• – das Bereitstellen von weiterem elektrisch isolierenden Material zwischen der weiteren Leiterbahn oder den Leiterbahnen und den ersten Kontaktbereichen

umfassen.The procedure can

• - Providing another trace or tracks;
• - Connecting the further conductor track with a plurality of the second contact regions or the further conductor tracks, each having a plurality of the second contact surfaces;
• - Providing further electrically insulating material between the further conductor track or the conductor tracks and the first contact areas

include.

In this case, the contacts (eg, contact fingers) may be made smaller, e.g. B. less thick or less wide, which saves material.

• – das Bereitstellen eines Verbindungsstrangs;
• – das Verbinden der elektrisch exponierten Teile des Verbindungsstrangs jeweils mit einem entsprechenden der ersten Kontaktbereiche, in elektrischem Kontakt mit den ersten Kontaktbereichen, mit den Patches angeordnet zwischen der Leiterbahn und den zweiten Kontaktbereichen. In einer weiteren Ausführungsform bilden die Patches Ringe aus elektrisch isolierendem Material um die Leiterbahn. Die Verwendung vorgefertigter Patches auf den Leiterbahnen vereinfacht den Zusammenbau.

According to one aspect, the trace is part of a connecting strand comprising the electrically insulating material in patches on the trace, wherein portions of the trace remain electrically exposed and the electrically exposed portions alternate with the patches along a longitudinal direction of the trace, comprising the method

• The provision of a connection string;
• - Connecting the electrically exposed parts of the connecting strand in each case with a corresponding one of the first contact regions, in electrical contact with the first contact regions, with the patches arranged between the conductor track and the second contact regions. In a further embodiment, the patches form rings of electrically insulating material around the conductor track. The use of pre-made patches on the tracks simplifies assembly.

In one aspect, the track is provided with a woven mat comprising a series of first strands that are parallel to one another and second strands that are transverse to the first strands woven through successive first strands in the series, one of the first strands comprises the conductor track and the second strands comprise the insulating material. In a further embodiment, each of the first strands comprises a trace, wherein interdigitated first and second subsets of the first strands are respectively connected to the plurality of first and second contact regions. Consequently, an application of insulating material is unnecessary. In one embodiment, multiple tracks may be woven in parallel into the mat. This facilitates positional control when connecting multiple tracks to a photovoltaic cell.

Solder material may be provided on the trace or traces, with the trace or traces connected to the first contact areas by heating the solder material. This facilitates the connection of the conductor tracks to the photovoltaic cell.

In an embodiment, the system comprises a further photovoltaic cell, wherein the interconnect is connected to a plurality of the second contact region on the further photovoltaic cell, electrically insulating material is provided between the interconnect and the first contact regions of the further photovoltaic cell, wherein the interconnect electrically connects the emitter and base contacts of the photovoltaic cell and the further photovoltaic cell. In another embodiment, slack is added to the trace between the photovoltaic cell and the other photovoltaic cell. In this embodiment, the system includes a plurality of photovoltaic cells connected in series. In this case, the trace may pass from one photovoltaic cell to the other and contact the base contacts in one and the emitter contacts in the other. In this way, the tracks can serve to connect contact fingers both in cells and between cells.

In another embodiment, the system slack is added to the trace between the photovoltaic cell and the other photovoltaic cell. This reduces the risk of harmful voltage in the case of relative movement between the photovoltaic cells.

In one embodiment, the photovoltaic cell is temporarily held in a bent state when the trace is connected to the first contacts of the photovoltaic cell, wherein the surface of the photovoltaic cell on which the trace is connected, in the bent state, a convex Curvature has. The surface on which the trace is joined has a convex curvature in the bent state, i. h., the center of the curvature is on the other side of the photovoltaic cell opposite this surface. This reduces the risk of harmful voltage through the tracks.

A photovoltaic cell system is provided which can be obtained by one of these manufacturing methods.

Claims (17)

A method of manufacturing a photovoltaic cell system, the system comprising a semiconductor substrate having a surface with interdigitated first and second contact regions which make contact with emitter and base contact regions in or on the semiconductor or base and emitter contact regions, respectively on the semiconductor, comprising the method Providing a connection string comprising a trace and electrically insulating material in rings around the trace; - Connecting parts of the conductor track between the rings to a plurality of the first contact areas, in electrical contact with the first contact areas, with insulating material of the rings between the conductor track and the second contact areas. The method of claim 1, wherein the connection string is provided on a spindle and the connection string is supplied from the spindle of the photovoltaic cell. The method of claim 1 or 2, comprising - Providing a plurality of connecting strands, each comprising a conductor track and electrically insulating material in rings around the conductor track of the connecting strand; - connecting parts of the conductors of each connecting strand between the rings of the connecting strand to the plurality of first contact regions, with the electrically insulating material of the rings between the conductor track and the second contact regions, wherein the conductor tracks of the connecting strands in parallel electrical contact with the first contact regions are connected. The method of claim 3, wherein the plurality of connection strings are fed in parallel from the spindle to the photovoltaic cell. Method according to one of the preceding claims, comprising Providing a further interconnect strand or other interconnect strands comprising a trace or traces and electrically insulating material in rings around the trace or traces; - Connecting parts of the conductor track of the further connection strand or each other connecting strand between the rings of the further connection strand with the plurality of second contact regions, with the electrically insulating material from the rings between the conductor track and the first contact regions, with a plurality of the second contact regions. The method of claim 5, wherein the further interconnect strand (s) is / are provided on a spindle, the method comprising supplying the interconnect strand and the further interconnect strand (s) in parallel from the spindle to the photovoltaic cell. Method according to one of the preceding claims, wherein the connecting strand, the plurality of connecting strands or the further connecting strand or strands and the connecting strand or strands are mounted on a flexible film and attached to the flexible film before bonding and with the film on the Contact areas are placed. Method according to one of the preceding claims, wherein the connecting strand, the plurality of connecting strands or the further connecting strand or strands and the connecting strand or strands are fed in parallel from the spindle of a flexible film and attached to the flexible film prior to bonding and with the Slide to be placed on the contact areas. Method according to one of the preceding claims, wherein the solder material is provided on the conductor track of the connecting strand or each connecting strand before connecting, wherein the conductor track or the conductor tracks are connected by heating the solder material with the first contact areas. The method of claim 9, wherein the brazing material is provided on the track of the connecting strand or each connecting strand after the attachment of the rings on the insulating paint. The method of claim 9 or 10, wherein the solder material is provided on the interconnect of the interconnect strand or each interconnect strand in further rings around the interconnect. The method of claim 1, wherein the system further comprises a further photovoltaic cell, the method comprising connecting portions of the interconnect of the interconnect strand between the rings to a plurality of the second contact regions on the further photovoltaic cell, with the electrically insulating material of FIG the rings between the conductor track and the first contact areas on the other photovoltaic cell. The method of claim 12, wherein between the photovoltaic cell and the further photovoltaic cell slack is added to the conductor. Method according to one of the preceding claims, wherein the photovoltaic cell is temporarily held in a bent state, when the conductor is connected to the first contacts of the photovoltaic cell, wherein the surface of the photovoltaic cell, on which the conductor is connected in the bent state has a convex curvature. Photovoltaic cell system obtainable by the manufacturing method according to any one of the preceding claims. A photovoltaic cell system according to claim 15, comprising A semiconductor substrate having a surface with interlocking first and second contact regions providing contact to emitter and base contact regions in the semiconductor or to base and emitter contact regions in the semiconductor; A connecting strand comprising a conductor track and electrically insulating material in rings around the track, with connection parts of the track between the rings, connected to a plurality of the first contact areas, in electrical contact with the first contact areas, with electrically insulating material from the rings between the track and the second contact regions, wherein the connecting strand extends beyond the semiconductor substrate. A system of photovoltaic cells according to claim 16, comprising a further photovoltaic cell, wherein parts of the conductor track of the connecting strand between the rings with a plurality of the second contact areas on the further photovoltaic cell are connected, with the electrically insulating material from the rings between the conductor track and the first contact areas on the other photovoltaic cell.

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