DE102010016976A1 - Method for interconnecting solar cells, involves assigning back contact solar cells on second and third electric guards to contact back led front face region according to back contact solar cells in series which are interconnected - Google Patents

Abstract

The method involves arranging the electric guards in series for interconnecting the front face contact solar cells (10) and back contact solar cells on carrier (20). The third electric guards for one back contact solar cell are arranged in the series and are connected with second electric guards for other back contact solar cell. The back contact solar cells on the second and third electric guards are assigned in each case to contact back led front face region according to back contact solar cells in series which are interconnected. An independent claim is included for solar cell interconnecting structure.

Description

The invention relates to a method for interconnecting solar cells to a module, wherein the solar cells are arranged with their backs on a base having electrical conductors, via which the solar cells are connected with their contacts, and to a solar cell interconnection, wherein the solar cells are arranged with their backs on a base, having electrical conductors over which the solar cells are connected with their contacts.

In order to provide suitable voltages or power with solar cells, it is known to interconnect them to larger units. To produce appropriate modules, the cells are connected in parallel or in series and embedded in a suitable transparent encapsulating material such as ethylene vinyl acetate (EVA). On the front side, corresponding modules are usually covered by a glass pane and on the back by a weather-resistant plastic composite film such as polyvinyl fluoride (TEDLAR) and polyester. The module itself is of a frame z. B. surrounded aluminum.

Typical silicon wafer-based solar cell modules have contacts on the front and back. For interconnecting the solar cells, the front contact of a solar cell is connected to the back contact of the following. Thus, an interconnection to strings is possible. In this case, the connectors between the cells must have a sufficient length to allow heat-related relative movements. This in turn means that the solar cells are arranged at certain distances from each other, so that non-active module surfaces arise. As a result, and due to the shutdown of the front side extending contacts such as contact fingers and busbars, which are electrically connected to the connectors, performance losses occur.

In the case of corresponding front-side contact solar cells, an electrically conductive grid applied on the side facing the light is usually composed of current collectors (grid fingers) and current conductors (busbars), usually by a continuous metal layer such as aluminum or a backside passivating silicon nitride layer with recesses for the aluminum -Contact connected as back contact. Also so-called bifacial cells are counted with translucent backside contacts to front contact solar cells.

The series connection of the corresponding solar cells is usually carried out in that the solar cells individually with as cell connector to be designated contact bands of z. B. tin-plated copper are soldered, then combined into a so-called string and connected in series. The strings are arranged in pallets and connected in series via other tinned copper strips.

In order to achieve higher efficiencies and thus achievements, back contact solar cells can be used, the two contacts on the back of the cell, d. H. the jet side facing away are arranged. As a result, unwanted shading is avoided because of the omission of the busbars and depending on the type of solar cell, possibly also the contact fingers on the front. Furthermore, the packing density of the solar cells can be increased from the module, since co-planar connectors can be used.

Corresponding rear-side contact solar cells typically distinguish between Metal Wrap Through (MWT) solar cells and Emitter Wrap Through (EWT) solar cells. For MWT solar cells there is a front contact and a back contact. By drilling in the semiconductor substrate - such as silicon wafer - then the front contact is guided to the back. The holes such as holes are z. B. metallized by an Ag conductive paste and the area around the puncture point on the back of the remaining area of the back so isolated that the current is passed from the front to the back and can be removed there. The advantage of this circuit is that no more light-covering current conductors are needed and a higher transparency of the front grille is thereby given.

In the case of the EWT solar cells, the n-layer is led directly through very small holes in the wafer disk directly onto the rear side where it is contacted by a point-like metal layer. Therefore one speaks also of point contact solar cells. The advantage of this cell is that the front grille on the front is completely eliminated, giving the best possible transparency for the incidence of light.

However, there is the disadvantage that the holes in the wafer make them susceptible to mechanical stress.

In order to avoid these disadvantages, it is known to interconnect back-side contact solar cells in a combination of foil and copper strips (see, for example, US Pat. DW Eikelboom et al. ). However, this leads to a mechanical stress on the solar cell, since the investment material surrounding the solar cell allows a relatively large lateral movement caused by shrinkage during the lamination process required for the production of the module and due high thermal expansion coefficient of the organic films can occur.

In various publications, wrap-through solar cells are described in order to establish contact between the emitter and the back of the solar cells, in order then to make an interconnection exclusively via rear contacts. For interconnecting backside contact solar cells, co-planar connectors are known. The connectors are metal-based and dielectrically coated, with special arrangements of the contact fingers on the cell backs allowing for thinner busbar designs. The connectors may be embodied in various geometrical shapes and fastened essentially via soldering methods at at least two locations on each cell. The disadvantage of this Verschaltungskonzepte is the complex positioning of cells and connectors and the limited cross-sections of the connector, since a surface connection can increase the fill factor.

An overview of the corresponding techniques can be found in the following publications:
D. Thorp, et al., Methods of contacting multi-junction silicon PV modules, 14th European PVSEC, Barcelona, 1997, p ;
A. Schoenecker, et al. "An industrial mc EWT solar cell with screen-printed metallization", 14th European PVSEC, Barcelona, 1997, p ;
M. Späth, et al "Solder version of 8 inch back-contacted solar cells", 15th PVSEC Shanghai, 2005, p. 1003 ;
F. Clement, et al. "Processing and Comprehensive Characterization of Screenprinted MC-Si Metal Wrap-Through (MWT) Solar Cells", 22nd European PVSEC, 2007, Milano, p. 1399 ;
Y. Meydbray, et al "Solder Joint Degradation in High Efficiency All Back Contact Solar Cells", 22nd European PVSEC, Milano, 2007, p. 2561 ;
U. Eitner, et al "A Modeling Approach to the Optimization of Interfaces for Back Contact Cells by Thermomechanical Simulation of Photovoltaic Modules", 23rd European PVSEC, Valencia, 2008, p. 2815 ;
K. Nakamura, et al. "Development of back contact Si Solar Cells and Modules in Pilot Production Line", 23rd European PVSEC, Valencia, 2008, p. 1006 ,

It is also known to use backsheets for interconnection. In this case, electrically conductive adhesive layers can be used to connect contacts. The electrically conductive adhesives can be applied by printing technology ( DW Eikelboom, et al. "Conductive adhesives for interconnection of busbarless emitter wrap-through solar cells on a structured metal foil", 17th PVSEC Fukuoka Japan, 2001, p. 1547 ).

The reference M. Späth, et al "A novel module assembly line using back-contact solar cells", 23rd European PVSEC, Valencia, 2008, p. 2917 , A method for producing a module can be seen in which a conductive back sheet has a wiring pattern for interconnecting the solar cells. Via a conductive paste, the electrically conductive regions of the backsheet are then connected to the solar cells. The solar cells to be interconnected are then arranged successively on the circuit board enabling the interconnection.

A method of the type mentioned for rear-side contact solar cells is known from US-A-5,972,732 or the US-A-5,951,786 refer to. In this case, electrical conductors are arranged on a base element to be designated as a carrier element, in order then to position the rear-side contact solar cells to be connected in such a way that their contacts to the desired interconnection are aligned with the electrical conductors. The encapsulation of the interconnected solar cells is then carried out in the usual way, ie that the solar cells are largely surrounded by an embedding mass, the lateral movements are exposed transversely to its surface extension, in particular by temperature fluctuations, which are subject to the modules, resulting in a damage to the solar cell itself and on the other hand, a release of the electrically conductive connections between back contacts and electrical conductors can be done.

The soft embedding of the solar cells in an investment material takes place against the background that mechanical loads should be avoided or reduced. However, measurements have shown that the movements of the solar cells in soft embedding material are 120 μm and exceed the expected temperature expansion by a factor of 4. Thus, the soft embedding leads to a high mechanical load, with the result that both serial connectors and cells can break themselves.

The present invention is based on the object, a method and a solar cell interconnection of the type mentioned in such a way that in addition to a simple interconnection of the cells mechanical stresses are reduced to the solar cells.

To solve the invention essentially provides that a rigid support is used as a base on which the electrical conductors are applied or formed from the surface that for interconnecting to be arranged in a row front side contact solar cells on the support for each front side Kontaktksolarzelle to be interconnected at least one first electrical conductor is provided, which is electrically connected to each rear side contact of a front-side contact solar cell, that protrudes from a respective front side of the front-side contact solar cell at least one cell connector projecting over a first edge of the front-side contact solar cell, the cell connector of a first front-side contact solar cell with a first electrical conductor to be arranged along the row second front-side contact solar cell is connected, wherein the cell connector is connected to the first electrical contact in between the first edge and this associated edge of the second front-side contact solar cell, that are connected to each other front side contact solar cells in series, or that for interconnecting to be arranged in a row back contact solar cells the carrier for each rear-side contact solar cell strip-shaped second and third electrical conductors are provided, the gegeneinan electrically insulated, the second electrical conductors being connected to front side region contacts guided to the rear side of the back side contact solar cell and the third electrical conductors being connected to at least one rear side contact of the respective back side contact solar cell, third electrical conductors for a first rear side contact solar cell to be arranged in series with second electrical conductors of a second one connected to the first rear-side contact solar cell in the row to be arranged rear side contact solar cell and third electrical conductors of the second series-arranged in the back contact solar cell with second electrical conductors for adjacent and opposite to the second back-contact solar cell to be arranged in the row to be arranged third back-contact solar cell, and that the back-contact solar cells then to the respectively associated second and third electrical conductors with her and the at least one rear side contact are placed and connected to the rear side guided area contacts and that correspondingly further back contact solar cells in the series are connected to each other.

According to the invention, there is a quasi-direct coupling of the solar cells to the inherently rigid support, which in particular stabilizes thin solar cells, such as silicon solar cells. The arrangement of the electrical conductors on the carrier cell connectors are avoided in back-contact solar cells and a connection of front-side contact solar cells via cell connectors with each other is omitted. This is followed by an electrical connection via the electrical conductors arranged on the carrier or formed from the carrier.

In order to avoid short circuits, it is further provided that the front-side contact solar cell is provided with electrical insulation in its first edge region, along which the cell connector extending from the solar cell is routed to the first electrical conductor connected to the rear-side contact of the adjacent front-side contact solar cell. In particular, however, it is provided that the edge region lying opposite the first edge region is also provided with electrical insulation in order to avoid that the cell connector running along this and connected to the first electrical contact can come into electrically conductive contact with the front region of the corresponding solar cell, causing a short circuit would occur.

In particular, it is provided that the carrier is a plate body made of a material from the group of glass, metal foam, ceramic foam, stiffened corrugated board provided with, water-repellent paint, light metal components, plastic plates is used.

When using a carrier consisting of an electrically conductive material, a layer or foil of electrically insulating material is applied to its side receiving the solar cell, and then the electrical conductors are arranged on the electrically insulating material.

When using a carrier consisting of electrically insulating material or a layer of electrically insulating material covering the carrier, the foils or ribbons forming the electrical conductors can be arranged and soldered on the side receiving the solar cells, or the electrical conductors can be applied by printing or spraying methods.

There is also the possibility that a metal layer is applied to the carrier, in particular by sputtering or by printing or screen printing, and then z. B. by laser or etching or lift-off technology, the electrical conductors are formed.

Another proposal provides that partially on at least some of the electrical conductors by z. B. Siebdruck- or spraying strip-shaped conductors are applied to improve the electrical contact with the solar cells to be arranged on these and to avoid or reduce undesirable contact resistance. It is also possible that adhesive material such as adhesive strips are applied to the carrier, via which the solar cells to be interconnected are connected to the carrier.

The electrically conductive connection between the electrical conductors and the contacts of the solar cells can then by heat, be carried out by laser or induction soldering or other suitable techniques for connecting conductors.

With regard to the rear-side contact solar cells to be interconnected, provision is made in particular for the second and / or third electrical conductors to be designed and arranged in comb-like fashion in the third and / or second electrical conductors. In this case, the third electrical conductors can be connected to the second electrical conductors via the third electrical conductors transverse to their longitudinal direction transverse conductor and vice versa. In particular, it is provided that the second and / or third electrical conductors are formed by means of strip material applied to the carrier paste material such as silver-containing paste material.

With regard to the contacting of the back-contact solar cells with the electrical conductors, the following procedures should be given as preferred. In this context, it should be noted that the front side area contacts present on the rear side are connected to front grid areas in an MWT solar cell and, in the case of an EWT cell, to the front-side doped semiconductor layer, that is to say the n layer in the case of a p-type substrate such as silicon.

In a back-side contact solar cell, it is provided that strip-shaped areas of the rear side or series-arranged areas of the rear side are formed as the back contact, which are electrically insulated from the front side area contacts arranged in rows on the rear side. In this case, to form the strip-shaped areas forming the back contact, printed conductors are applied to the rear side of the rear-side contact solar cell, in particular by soldering, gluing, printing or plasma spraying or fixed on the back.

The front side area contacts present on the rear side of the rear side contact solar cell are arranged in second rows, in the direction of the rear side contact solar cells to be arranged in series, along each second one. Row is arranged a front side contact area points exposed strip-shaped insulation, which are bounded by the strip-shaped back contact areas. When positioning the rear side contact solar cell, the strip-shaped insulations are placed on the arranged on the support second electrical conductor and then the front side area contacts with the second electrical conductors z. B. connected by heat input, laser or induction soldering. In this case, it is provided in particular that prior to positioning of the rear-side contact solar cells on the carrier applied to the rear side piercing front side area contacts an electrical material such as silver or Zinnleitpaste or z. B. in a tin melt in a wave bath with an electrically conductive material are covered. Alternatively or additionally, soldering points can be arranged on the second electrical conductors in the region of the front side area contact areas to be positioned, which ensure the electrically conductive connection to the front side area contacts.

Furthermore, the invention relates to a solar cell interconnection, comprising a self-rigid support having first, second and / or third electrical conductors, and arranged in a row front-side contact solar cells or arranged in a row back contact solar cells, which are arranged with their backs on the intrinsically rigid support and on the first, second and / or third electrical conductor according to at least one of the method steps of claims 1 to 14 are connected.

For more details, advantages and features of the invention will become apparent not only from the claims, the features to be taken these features - alone and / or in combination - but also from the following description of the drawing to be taken preferred embodiments.

Show it:

1 a schematic representation of the method steps for producing a front-side contact solar cell,

2 A first embodiment of a carrier with applied thereto electrical conductors,

3 a second embodiment of a carrier with electrical conductors,

4 A third embodiment of a carrier with electrical conductors,

5 a schematic representation of a carrier with electrical conductors and applied adhesive strips,

6 a schematic representation of the arrangement of front side contact solar cells on the carrier according to 5 .

7 on the carrier according to 5 and 6 arranged front-side contact solar cells,

8th the arrangement according to 7 with front-side contact solar cells connected to the electrical conductors on the support,

9 the arrangement according to 8th with a transparent cover,

10 a front side of a back-side contact solar cell,

11 the solar cell according to 10 in rear view,

12 the solar cell according to 10 arranged on a support with first and second electrical conductors,

13 the solar cell according to 12 with contacts and insulations on the back,

14 arranged on a support second and third electrical conductors,

15 the arrangement according to 14 with openings applied to the second electrical conductors openings having insulation,

16 the arrangement according to 15 with rear-side contact solar cells arranged thereon,

17 the arrangement according to 16 in which the carrier is completely equipped with back-contact solar cells, and

18 the arrangement according to 17 with a transparent cover.

With reference to the figures, in which the same reference numerals are used in principle for the same elements, the production of modules is shown in principle, having in series connected solar cells. Here are the refer 1 to 9 on the production of a module consisting of front-side contact solar cells and the 10 to 18 to fabricating a module consisting of back contact solar cells.

Basically, the common method is that the solar cells are arranged on an intrinsically rigid carrier, which ensures that the undesirable according to the prior art lateral movement of the solar cell is reduced or largely prevented, so that the risk of breakage of solar cells is prevented. At the same time a simplified interconnection is provided, which ensures a secure electrically conductive connection between the solar cells connected in series.

Of the 1 is purely a principle manufacturing method of Fronseitenkontakt solar cell 10 refer to. Thus, a p-junction P-type silicon substrate wafer is formed 11 with front antireflection coating 12 and backside metallization 14 , which forms a back contact and in particular consists of aluminum, on the front side of the wafer 11 an electrically conductive grid consisting of current collectors 16 (Grid fingers) and current conductors 18 (Busbars) applied. To from the backside contact 14 To be able to derive current in the exemplary embodiment on the metal layer 14 busbars 20 made of silver, Cu or Sn, for example, to ensure contact with first electrical conductors arranged on a support in the manner described below.

Furthermore, the wafer 11 in his perpendicular to the busbars 18 or busbars 20 running edges 22 . 24 isolated. On the busbars 18 then become cell connectors 24 soldered, which may for example consist of copper. The cell connectors 24 stand with a section 25 with a length X over the edge 22 in front. The length may be, for example, 1 mm to 5 mm.

According to manufactured front side contact solar cells 10 be according to the teaching of the invention on a self-rigid carrier 26 arranged and interconnected in series. The carrier 26 consists of a rigid material and is basically a plate body. This may consist of glass, metal foam, ceramic foam, but also of a stiffened corrugated board, which is coated with a water-repellent paint. Lightweight components, plastic sheets such as printed circuit boards or other suitable materials are also suitable.

In the embodiment of the carrier 26 be a glass plate, for example, 3 mm to 4 mm thick, without causing any limitations of the teaching of the invention.

As the carrier 26 made of glass, it does not require a surface insulation. However, should the carrier consist of an electrically conductive material, then the solar cells will first be applied to them 10 receiving side applied an insulating layer or applied a corresponding film.

According to the embodiment of 2 be on the carrier 26 so on his the solar cells 10 receiving surface 28 , Tracks 30 . 32 . 34 applied as the first electrical conductor. These run along rows along which the solar cells 10 and the backside busbars 20 be aligned and positioned. For this purpose, a screen printing process or a thermal spraying process or plasma spraying process can be used. The tracks 30 . 32 . 34 should have thicknesses between 10 microns to 50 microns, without the numerical values being to be understood as limiting the protection.

Alternatively, metallic foils or ribbons can also be applied to the glass plate, ie the carrier 26 be soldered.

The tracks 30 . 32 . 34 are mentioned arranged in rows and spaced from each other such that in the manufacture of the module the busbars 20 So the backside contacts of the front side contact solar cells 10 come to this to lie down. Furthermore, edge-side conductor tracks 32 . 34 with cross connectors 36 . 38 connected in the usual way a series connection of the conductors to be designated as the first electrical conductor 30 . 32 . 34 to arrange and with these to be contacted front side contact solar cells 10 sure. In that regard, however, reference is made to well-known techniques that enable series connection.

Of the 3 is a variant of the representation of 2 refer to. So will the carrier 26 For example, in a sputtering process, a 0.1 μm to 1 μm thick metal layer is applied. Subsequently, a structuring z. Example by means of laser or with etching or lift-off techniques, so that individual conductive and electrically isolated from each other areas 40 arise. To increase the conductivity, for example, 10 .mu.m to 50 .mu.m thick conductor tracks 42 according to the tracks 30 . 32 . 34 of the 2 be applied from copper by suitable methods such as screen printing, thermal spraying or plasma spraying to increase the conductivity. The tracks 42 run according to those of 2 and are thus on the busbars 12 and the cell connectors arranged thereon 24 geometrically aligned.

The 4 should illustrate in principle that by screen printing a 5 microns to 10 microns thick metal layer is applied, which corresponds to the 3 is structured. The individual metal layer areas are with 44 characterized. The optionally be applied to this conductor tracks bear the reference numeral 42 according to the 3 ,

On the z. B. according to the 2 to 4 prepared carrier 26 , which is for interconnecting the front side contact solar cells 10 required first electrical conductor, which consists of mutually electrically insulated metal surfaces 40 . 44 or individual tracks 30 . 32 . 34 or on the metal surfaces 40 . 44 additionally applied conductor tracks 42 will be made according to the 5 along the front-side contact solar cells to be aligned in a row, ie along the conductor tracks 30 . 32 . 34 . 42 , Adhesive strips 46 . 48 applied with good electrical insulating properties. You can see that the adhesive strips 46 . 48 are arranged such that contact areas of both the metal layers 40 . 42 as well as arranged on these tracks 42 are omitted.

On the corresponding carrier 26 then become the front-side contact solar cells 10 arranged such that the protruding portions 25 the cell connector 24 on the metal surfaces 40 . 44 or arranged on these conductor tracks 42 or the conductor tracks 30 . 32 . 34 rest and contact them, one of the upstream or downstream solar cell 10 are assigned to the same row. This is in principle based on the 5 and 6 clarified. So will the metal surface 50 with the tracks 52 . 54 the front-side contact cell 56 positioned so that the cell connectors 24 on the tracks 52 . 54 to lie down. The lower edge runs along 58 the front side contact solar cell 56 not aligned to the bottom edge 60 of the metal area 50 but shifted upwards in the drawing. This is indicated by the dashed line 62 be symbolized. Thus, the lower portion of the metal surface remains 50 and the tracks 52 . 54 uncovered. The in the 6 below the front-side contact solar cell 56 arranged solar cell 63 is now so on the associated metal surface 64 with the tracks 66 . 68 arranged that the protruding sections 25 or ends of the cell connectors 24 with the exposed ends of the tracks 52 . 54 can be contacted without the front side contact solar cell 62 this or the metal surface 40 contacted. As a precautionary measure, therefore, there is also the border area 22 . 24 electrically isolated, as related to the 1 has been explained.

By this arrangement, a series connection of the solar cells 56 . 63 done without the cell connectors 24 with the back of the adjacent solar cell, in the embodiment with the solar cell 56 , must be connected, as is the case in the prior art. Rather, the electrically conductive connection between the solar cells 56 . 63 over the electrically conductive surface 50 and the tracks 52 . 54 on the carrier 26 are arranged.

To improve the electrical contact conductive pastes (Ag, Cu, Sn solder paste) with a dispenser at least partially on the electrically conductive surface 50 or the conductor tracks 52 . 54 previously applied.

The fixation of the solar cells 56 . 63 on the carrier 26 can over the adhesive strips 46 . 48 respectively. Alternatively and additionally, the solar cells 56 . 63 on the rear side, preferably made of aluminum 14 Tin sheets have to a Solder like ultrasonic soldering with the metal surfaces 40 . 44 . 50 make.

After the solar cells 56 . 63 according to the procedure explained above on the carrier 26 and the metal surfaces present on it 40 . 44 . 50 and the adhesive surfaces 46 . 48 are arranged and fixed, and outgoing from the outer front-side contact solar cell cell connector, the cross connector 36 . 38 or busbars overlap or come to lie on these, as can be seen from the drawing representations, by for example Induktivlötverfahren or laser soldering or suitable heat input, the required contacting the protruding sections 25 cell connector 24 with the associated conductor tracks of the front side contact solar cells arranged in series or downstream, or with the cross connectors 36 . 38 be performed in order to achieve the desired series connection. The corresponding contacts are in the 8th through points 70 . 72 indicated.

The cell connectors 22 can with the busbars or cross connectors 36 . 38 or the tracks on the carrier 26 or the metal layer 40 . 44 run, be connected by gluing or soldering.

After the front side contact solar cells 10 . 56 . 63 properly on the carrier 26 , ie, on the each solar cell 10 . 56 . 63 associated conductor tracks 30 . 32 or metal surfaces 40 . 44 . 50 with the tracks 42 . 52 . 54 arranged and with these or the cross connectors 36 . 38 have been properly electrically connected, is to complete the module on the solar cells 10 . 56 . 63 a thin foil, for example made of EVA, silicone or some other synthetic resin and then a glass plate 74 arranged to the solar cells 10 . 56 . 63 embed. Then the relevant unit is enclosed on the edge. In that regard, however, reference is sufficiently made to known techniques.

Based on 10 to 18 is the teaching of the invention for interconnecting backside contact solar cells 100 be explained. This is exemplified by a metal wrap through (MWT) solar cell.

The 10 and 11 are front and rear views of a corresponding MWT solar cell 100 refer to. The front 102 has a front grid 104 and metallized conductive channels 106 on that the function of the busbars 18 the front side contact solar cell 10 with the restriction that in the embodiment each channel 106 Electricity from a smaller area of the solar cell 100 dissipates, in the embodiment of 1/16 of the solar cell surface. Therefore, small diameters are sufficient for the channels 106 and short lengths are enough to effectively drain the stream.

The channels or feedthroughs 106 kick on the back 110 the solar cell 100 and are used as front panel contacts 112 referred to in rows 114 . 116 are arranged. These are n-type contacts if the wafer consists of a p-type substrate such as p-type silicon wafer.

The n-contacts 112 are furthermore opposite the back 110 electrically isolated.

Furthermore, in the 11 Rear contacts referred to as p-contacts 118 shown in the embodiment punctiform and also in rows 120 . 122 are arranged. Of course, the p-contacts can also be formed strip-shaped, between the rows 114 . 116 the n-contacts 112 run.

The back or p contacts 120 usually consist of an Ag-conductive paste to form metallic conductors can. But they can also be designed as strip-shaped Sn-conductor tracks on the surface Al back contact.

Mentioned are the p-contacts 120 Not absolutely necessary, since it is possible to glue electrical conductors directly to the back contact layer made of aluminum using adhesive technology. In that regard, the MWT solar cell 100 a back on how these related to the 1 has been explained, that can be metallized on the back, wherein the areas of the back-piercing channels 106 are omitted. Thus, it is also possible to use a Ultraschalllötverfahren tinning the aluminum back so that wide traces are prepared as p-contacts, as has been addressed.

This should be on hand 13 be clarified. So are the p-contacts as tracks 124 . 126 formed between the ones in the ranks 114 . 116 arranged n-contacts 112 run, in turn, of a strip-like insulation 128 . 130 are covered to the p-contacts 124 . 126 towards the n-contacts 112 electrically isolate. The insulations 128 . 130 show in the range of n-contacts 112 Cutouts on, so that the n-contacts 112 are omitted.

The tracks 124 . 126 can be applied instead of soldering by gluing (using conductive adhesive or solder paste) or by plasma spraying.

The insulation 128 . 130 can be screen printed on the back of the MWT cell 100 to be ordered.

For equipping a carrier 26 corresponding inherently rigid carrier 132 with appropriately prepared MWT solar cells 100 becomes the carrier 132 according to the 14 and 15 prepared as follows.

According to the course of the ladder 124 . 126 Making the p contacts or back contacts will be on the vehicle 132 first tracks 134 . 136 . 138 arranged over a transverse conductor 140 connected to each other. A corresponding one from the tracks 134 . 136 . 138 and the cross conductor 140 Existing units, referred to as third electrical conductors, span an area that is the area of a MWT solar cell 100 equivalent. On the appropriate unit is then according to the 16 a MWT solar cell 100 positioned.

Between the first strip-shaped tracks 134 . 136 . 138 become second traces 142 . 144 . 146 . 148 and arranged opposite to the first electrically insulating, for contacting the n-contacts 116 are determined. The second tracks 142 . 144 . 146 . 148 are referred to as second electrical conductors. In this case, the second conductor tracks assigned to a solar cell extend 142 . 144 . 146 . 148 such that they are connected to the adjacent first conductor tracks intended for an adjacent solar cell to be arranged in the row, or to the busbars 150 . 152 be contacted, in the edge region of the carrier 132 run and the series connection of the on the carrier 132 MWT solar cells to be arranged 100 to ensure.

As a result, the second printed conductors extend in the exemplary embodiment 142 . 144 . 146 . 148 to the power bus 150 and otherwise the illustration is according to 14 self-explanatory in this respect.

By the intermeshing of the mutually electrically insulated first and second conductor tracks 134 . 136 . 138 respectively. 142 . 144 . 146 . 148 and overlapping the second traces 142 . 144 . 146 . 148 with the cross conductor 140 , which connects the adjacent first tracks, the desired series connection takes place, since this the n-contacts 116 a solar cell with the p-contacts of the series in front or downstream solar cell are electrically connected. The serial connection of the MWT or backside contact solar cell 100 takes place, therefore, by inter-engaging tracks, which have the widest possible width and thus a high conductivity.

In the illustration in 12 is a MWT solar cell 100 shown in plan view, wherein the first and second interconnects, which are connected to the n and p contacts are indicated.

In order to avoid short circuits, it may further be provided that the second interconnects that make contact with the n contacts 116 produce, so the tracks 142 . 144 . 146 . 148 according to the 15 with a layer consisting of electrically insulating material 152 are covered, the recesses 154 at positions that those of the n-contacts 116 when on the carrier 132 arranged MWT solar cells correspond. In the corresponding recesses or holes 154 can z. B. in a screen printing z. For example, be made of silver or tin conductive paste or applied by means of a thermal spraying process or plasma spraying Sn soldering points. Alternatively, the entire plate 132 for tinning the point contacts are pulled over a tin melt (wave pool). This measure ensures that the required contact between the n-contacts 116 and the second conductor tracks, which are referred to as second electrical conductors 142 . 144 . 146 . 148 he follows.

As is clear from the 16 results, then the MWT solar cells 100 to the second and third electrical conductors, so the first conductor tracks having a comb geometry 134 . 136 . 138 with this connecting cross conductor 114 as well as the second tracks 142 . 144 . 146 . 148 positioned and connected to it. The interconnection of the solar cells 100 can be done by Induktivlötverfahren, by laser soldering of the contact points or by appropriate heat during the lamination process.

The complete with the solar cells 100 equipped carriers 132 is the 17 refer to. It also recognizes that the solar cells 100 are connected such that the upper busbars 150 . 156 on the one hand the plus and on the other hand the minus pole of the module. Then, in the usual way, arranged in rows and connected in series solar cells 100 applied a film of synthetic resin such as EVA or poured over the entire surface with a casting resin, then with a glass plate 160 be covered to provide a finished module, wherein the edge is enclosed accordingly.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 5972732A [0015]
• US 5951786 A [0015]

Cited non-patent literature

• DW Eikelboom et al. [0010]
• D. Thorp, et al "Methods of Contacting multi junction silicon PV modules", 14th European PVSEC, Barcelona, 1997, p [0012]
• A. Schoenecker, et al "An industrial mc EWT solar cell with screen-printed metallization" 14th European PVSEC, Barcelona, 1997, p [0012]
• M. Späth, et al "Solder version of 8 inch back-contacted solar cells", 15th PVSEC Shanghai, 2005, p. 1003 [0012]
• F. Clement, et al. "Processing and Comprehensive Characterization of Screenprinted MC-Si Metal Wrap-Through (MWT) Solar Cells", 22nd European PVSEC, 2007, Milano, p. 1399 [0012]
• Y. Meydbray, et al "Solder Joint Degradation in High Efficiency All Back Contact Solar Cells", 22nd European PVSEC, Milano, 2007, p. 2561 [0012]
• U. Eitner, et al. "A Modeling Approach to the Optimization of Interfaces for Back Contact Cells by Thermomechanical Simulation of Photovoltaic Modules", 23rd European PVSEC, Valencia, 2008, p. 2815 [0012]
• K. Nakamura, et al. "Development of back contact Si Solar Cells and Modules in Pilot Production Line", 23rd European PVSEC, Valencia, 2008, p. 1006 [0012]
• DW Eikelboom, et al. "Conductive adhesives for interconnection of busbarless emitter wrap-through solar cells on a structured metal foil", 17th PVSEC Fukuoka Japan, 2001, p. 1547 [0013]
• M. Späth, et al "A novel module assembly line using back-contact solar cells", 23rd European PVSEC, Valencia, 2008, p. 2917 [0014]

Claims (15)

A method for interconnecting solar cells to a module, wherein the solar cells are arranged with their backs on a base having electrical conductors, via which the solar cells are connected to their contacts, characterized in that a rigid support is used as a base, on which the electrical conductors are applied or formed from the surface thereof, that for interconnecting front side contact solar cells on the support for each front side contact solar cell to be connected at least a first electrical conductor is provided, which is electrically conductively connected to rear side contact of a front side contact solar cell that from respective front side the front-side contact solar cell emanates at least one cell connector projecting beyond a first edge of the front-side contact solar cell that the cell connector of a first front-side contact solar cell with a first electrical Conductor of a second front side contact solar cell to be adjacently arranged along the row, the cell connector being connected to the first electrical contact in between the first edge and the associated edge of the second front side contact solar cell, and correspondingly connecting further front side contact solar cells in the row; Interconnecting back-side contact solar cells to be arranged on the support for each back-side contact solar cell strip-shaped second and third electrical conductors are provided, which are electrically insulated from each other, wherein second electrical conductors are connected to back-guided front side area contacts and third electrical conductors with at least one rear side contact of the respective back-contact solar cell wherein third electrical conductors for a first in-line back contact solar cell having a second electrical L a second back-contact solar cell to be arranged adjacent to the first back-contact solar cell in the row, and third electrical conductors of the second in-line back-contact solar cell are connected to second electrical conductors for a third back-side solar cell to be arranged adjacent to the second back-contact solar cell in the row; the rear side contact solar cells are then placed on and connected to the respective associated second and third electrical conductors with their front side region contacts guided to the rear side and the at least one rear side contact, and correspondingly further back contact solar cells are connected in series. A method according to claim 1, characterized in that a plate body made of a material or a combination of materials from the group glass, metal foam, ceramic foam, stiffened corrugated cardboard provided with water-repellent paint, light metal components, plastic plate such as printed circuit board is used as the carrier. A method according to claim 1 or 2, characterized in that when using a carrier consisting of an electrically conductive material on its side on which the solar cells are arranged, a layer or foil of electrically insulating material is applied, and that on the electrically insulating material the electrical conductors are applied. Method according to at least one of the preceding claims, characterized in that when using a consisting of electrically insulating material carrier or a carrier covering layer of electrically insulating material on the solar cell receiving side of the electrical conductor forming films or ribbons arranged and soldered or by printing or by spraying the electrical conductors are applied. Method according to at least one of the preceding claims, characterized in that on the carrier, a metal layer is applied in particular by sputtering or by printing or screen printing method and that subsequently z. B. by laser or etching or lift-off techniques, the electrical conductors are formed. Method according to at least one of the preceding claims, characterized in that partially on at least some of the electrical conductors by means of z. B. screen printing or spraying a strip-shaped conductor is applied. Method according to at least one of the preceding claims, characterized in that adhesive material such as adhesive strip material is applied to the carrier, via which the solar cells to be interconnected are connected to the carrier. Method according to at least one of the preceding claims, characterized in that the front-side contact solar cell in at least one, preferably in both transverse to the longitudinal extent of the cell connector extending transverse edges is electrically insulated or provided with an electrical insulation. Method according to at least one of the preceding claims, characterized in that the cell connectors such as copper strips with the first electrical conductor and / or the solar cell with their back to the first and / or third electrical conductor by heat input, inductive or laser soldering are connected, previously possibly applied to the back of the solar cell, a solder material such as tin-sheet. Method according to at least one of the preceding claims, characterized in that the second electrical conductors in a comb-like manner surround the third electrical conductors at a distance, that the third electrical conductors connected to the rear side contacts of the rear-side contact solar cells have a transverse conductor extending transversely to the solar cells to be arranged in series, for interconnection the solar cells are connected to the second electrical conductors to be connected to the front side area contacts of a solar cell adjacent to the row. Method according to at least one of the preceding claims, characterized in that the second and third electrical conductors are formed by paste material applied in strip form on the carrier, such as silver, Cu, Sn. Method according to at least one of the preceding claims, characterized in that strip-shaped regions are formed on the back or series-arranged regions of the rear side of the back-contact solar cell as the back contact, which are electrically insulated from the series-connected front side region contacts. Method according to at least one of the preceding claims, characterized in that for forming the strip-shaped regions conductor tracks are applied or fixed on the rear side of the back contact solar cell, in particular by soldering, gluing, printing or plasma spraying, that the front side area contacts guided to the back of a relative to the strip-shaped Rear side contacts electrically insulating insulating strip are surrounded by recessing the front side area contacts, and that when positioning the back-side contact solar cell, the strip-shaped insulation placed on the second electrical conductor and then the front side area contacts and z. B. by heat input, laser or induction soldering are connected, that the second electrical conductors are covered by an electrical insulation, which has recesses in the areas in which the front side area contacts when positioning the back-side contact solar cells on the support. Method according to at least one of the preceding claims, characterized in that prior to positioning the back contact solar cells on the carrier on the front side area contacts and / or the recessed areas of the second electrical conductor, an electrically conductive material such as silver or Zinnleitpaste applied or z. B. in a wave bath such as tin melt bath are covered with an electrically conductive material. A solar cell interconnect comprising a rigid support having first, second and / or third electrical conductors, and front-side contact solar cells arranged in a row or back-contact solar cells arranged in a row, arranged with their backs on the intrinsically rigid support and via the first, second and / or third electrical cells Ladder are interconnected according to at least one of the method steps of claims 1 to 14.

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