WO2019228598A1

WO2019228598A1 - A solar panel comprising low reflectance tabbing ribbons

Info

Publication number: WO2019228598A1
Application number: PCT/DK2019/050150
Authority: WO
Inventors: Rasmus Schmidt DAVIDSEN; Ole Hansen; Sune Thorsteinsson; Peter Behrensdorff Poulsen; Beniamino IANDOLO; Peter Torben Tang; Io Mizushima
Original assignee: Danmarks Tekniske Universitet; Ipu
Priority date: 2018-05-28
Filing date: 2019-05-14
Publication date: 2019-12-05

Abstract

The invention relates to a solar panel comprising a plurality of solar cells, each solar cell comprising one or more bus bars, and tabbing ribbons; wherein each solar cell is connected to an attachment site of one or more tabbing ribbons via its one or more bus bars; wherein each tabbing ribbon, which is connected to a bus bar, comprises a coated region comprising an inorganic coating and a region free of said inorganic coating, the inorganic coating providing less than 10 % reflectance of light, incident on the inorganic coating at a normal angle of incidence, in a given spectrum, said spectrum comprising wavelengths in the range from 400 nm to 700 nm; wherein the plurality of solar cells are electrically connected via the tabbing ribbons to form the solar panel; and wherein each attachment site is located within said coating free regions of the tabbing ribbons. The invention further relates to a method of manufacturing a solar panel. The invention further relates to a machine for production of tabbing ribbons. The invention further relates to a terrestrial object comprising said solar panel.

Description

i

A SOLAR PANEL COMPRISING LOW REFLECTANCE TABBING RIBBONS Field of the invention

[0001] This invention relates to a solar panel, and particularly to a solar panel comprising low reflectance tabbing ribbons. The invention further relates to a method of manufacturing such solar panels. The invention further relates to a machine for production of tabbing ribbons. The invention further relates to a building comprising a solar panel.

Background of the invention

[0002] Solar panels becoming more and more common due to focus on renewable energy and at the same time increasing ratio of power generation efficiency to costs.

[0003] As solar panels are increasingly used on building surfaces, such as roofs and outer walls, their appearance increasingly contribute to the overall appearance of such buildings.

[0004] Some individual solar cells provide different customized appearances. One example is international patent application WO 2017/123798 Al, which discloses colouring of metal contacts of a solar cell.

[0005] However, a problem still remains in providing solar panels with an aesthetic attractive appearance.

Summary of the invention [0006] The invention relates to a solar panel comprising a plurality of solar cells, each solar cell comprising one or more bus bars; and tabbing ribbons; wherein each solar cell is connected to an attachment site of one or more tabbing ribbons via its one or more bus bars, wherein each tabbing ribbon, which is connected to a bus bar, comprises a coated region comprising an inorganic coating and a region free of said inorganic coating, the inorganic coating providing less than 10 % reflectance of light, incident on the inorganic coating at a normal angle of incidence, in a given spectrum, said spectrum comprising wavelengths in the range from 400 nm to 700 nm; wherein the plurality of solar cells are electrically connected via the tabbing ribbons to form the solar panel; and wherein each attachment site is located within said coating free regions of the tabbing ribbons. [0007] One advantage of the present invention is that solar panels having an attractive aesthetic appearance combined with a durable and long-lasting design. Particularly, the solar panel may have a very desirable appearance, due to the very low reflectance of light from the bus bar connected tabbing ribbons, while having a robust design against typical weather conditions, hereunder especially sun light. Thus, the inorganic coating may provide a low reflectance of light without being subject to any considerable fading or other unattractive colour alterations. This high degree of preservation of the very low reflectance of light may thus be preserved, and thereby provide the attractive look without compromising the life-time of the solar panel. Here, an attractive aesthetic appearance may in an embodiment be a low-contrast, uniform appearance of the solar panel.

[0008] Another advantage of the present invention is that a durable and long-lasting solar panels are provided, being at the same time un-disturbing and un-distracting to its surroundings in the sense that annoying and disturbing reflections and appearance is avoided by means of the very low reflectance of light from the tabbing ribbons. This helps to avoid causing distractions to e.g. nearby traffic, where drivers might otherwise have been distracted or annoyed by reflections of solar light from solar panels or parts thereof. Also, it may help to comply with potential legal requirements for low reflectance of e.g. wall or roof materials.

[0009] Particularly, the above advantages may be obtained while attaining an effective and durable conduction of generated solar power within the solar panel, necessary for effective operation of the solar panel.

[0010] Also, these advantages may be particularly pronounced when the solar panels are integrated into building materials and thus provided e.g. as building integrated photovoltaics. [0011] Having a reflectance below 10 % is advantageous in that the tabbing ribbons may have a low contrast compared to the solar cells and thereby allowing the tabbing ribbons to blend in with the solar cells. This makes it difficult to see the tabbing ribbons from an outside observer’s point of view, and the solar panel may appear as a homogeneous surface.

[0012] Having both a coated region and a region free of coating is advantageous in that the coated regions may only be disposed at locations on the solar panel that are visible from the front side of the solar panel, and the regions free of coating may only be disposed at locations on the solar panel that is hidden by the solar cells and not visible from the front side of the solar panel.

[0013] This further has the advantage that the inorganic coating does not need to be applied to all regions of the tabbing bar, thus presenting a materials saving and an accompanied reduction in manufacturing costs.

[0014] An attachment site may be any site configured to attach to a bus bar and transfer electric energy between the bus bar and the tabbing ribbon.

[0015] The attachment site is understood as being positioned on a side of the tabbing ribbon that is either in contact with a bus bar of a solar cell or an electrically conductive back plate of a solar cell. However, the attachment site may not be limited to an individual side of a tabbing ribbon and may also comprise a complete circumferential section of a tabbing ribbon.

[0016] In the present context the term “tabbing ribbon” is understood as an electrically conductor providing electrical connection between individual solar cells in a solar panel. The tabbing ribbons are, during assembly of the solar panel, attached to electrical contacts of the individual solar cells. At least some of the tabbing ribbons are attached to the bus bars of the individual solar cells, during assembly of the solar panel.

[0017] In the present context the term“bus bar” is understood as the front side electrical contacts of the individual solar cells, i.e. the electrical contacts on the side of the solar cells receiving sun light during operation. Bus bars are incased in the individual solar cells during manufacturing of these solar cells, and are therefore provided as a part of such solar cells.

[0018] In the present context the term“solar panel” is understood as an assembly or module of a plurality of individual solar cells typically in a grid structure, typically including several strings of serial coupled individual solar cells connected in parallel to provide the desired output voltage and current.

[0019] In the present context the term“solar cell” is understood as an individual electrical device converting light into electricity. Solar cells may also be referred to as a photovoltaic cell. Individual solar cells may be combined to form modules also known as solar panels.

[0020] According to an embodiment of the invention, the attachment sites comprises sites where the tabbing ribbons are soldered to the bus bars.

[0021] Soldering a tabbing ribbon onto a bus bar ensures that the tabbing ribbon and the bus bar are mutually fixed to one another and in electric contact such that an electric current can flow between the two.

[0022] The soldering material may comprise any material normally used as solder material. Examples of such solder material include e.g. tin (Sn), lead (Pb), silver (Ag), etc. In some applications, lead may be exchanged for e.g. Bismuth (Bi). [0023] According to another embodiment of the invention, the attachment sites comprises sites where the tabbing ribbons are glued to the bus bars using a conductive adhesive.

[0024] According to an embodiment of the invention, the inorganic coating provides a reflectance of light, incident on the inorganic coating at a normal angle of incidence, being between 0.01 and 10 % in a given spectrum, such as between 0.1 and 10 %, such as between 0.5 and 10 %, such as between 1 and 10%, said spectrum comprising wavelengths in the range from 400 nm to 700 nm. In a further embodiment, the above reflectance is obtained where said spectrum comprises wavelengths in the range from 300 nm to 800 nm.

[0025] According to an embodiment of the invention, the inorganic coating provides less than 5 % reflectance of light in the spectrum comprising wavelengths in the range from 400 nm to 700 nm.

[0026] According to an embodiment of the invention, the inorganic coating provides a reflectance of light, incident on the inorganic coating at a normal angle of incidence, being between 0.01 and 5 % in a given spectrum, such as between 0.1 and 5 %, such as between 0.5 and 5 %, such as between 1 and 5%, said spectrum comprising wavelengths in the range from 400 nm to 700 nm. In a further embodiment, the above reflectance is obtained where said spectrum comprises wavelengths in the range from 300 nm to 800 nm.

[0027] Gluing a tabbing ribbon onto a bus bar using an electrically conductive adhesive ensures that the tabbing ribbon and the bus bar are mutually fixed to one another and in electric contact such that an electric current can flow between the two.

[0028] Using an adhesive as opposed to a solder may be advantageous in that lower temperatures can be used during panel production.

[0029] According to an embodiment of the invention, each solar cell comprises at least one bus bar. [0030] According to an embodiment of the invention, each solar cell comprises at least two bus bars.

[0031] Increasing the number of bus bars in a solar cell, beyond a single bus bar, is advantageous in that a reduction in internal resistance losses may be achieved due to a shorter distance between individual bus bars. [0032] A further advantage in increasing the number of bus bars is that the bus bars may be designed more narrow, since each bus bar has to carry a correspondingly smaller current. This may present a further cost saving since less bus bar material is needed.

[0033] According to an embodiment of the invention, each solar cell comprises three or more bus bars. [0034] According to an embodiment of the invention, the solar panel further comprises comprising at least two bussing ribbons arranged to collect a generated current () from the interconnected solar cells.

[0035] The bussing ribbons are advantageous in that they collect current generated in all of the solar cells, and thereby serve as electrical terminals for the entire solar panel.

[0036] According to an embodiment of the invention, the bussing ribbons are coated with the inorganic coating.

[0037] Coating the bussing ribbons with the inorganic coating is advantageous in that if the bussing ribbons are exposed on the front side of the solar panel, they may also become difficult to observe due to the low reflectance of light.

[0038] According to an embodiment of the invention, the tabbing ribbons have a width substantially equal to a width of the bus bars.

[0039] Having the width of the tabbing bars substantially equal to the width of the bus bars is advantageous in that the electrical conductivity between the two becomes as high as possible, and furthermore, the tabbing ribbons may not introduce any shadowing effects on the solar cell.

[0040] According to an embodiment of the invention, the tabbing ribbons have a width corresponding to at least the width of the bus bars.

[0041] Having the width of the tabbing bars corresponding at least to the width of the bus bars is advantageous in that the electrical conductivity between the two becomes as high as possible. [0042] According to an embodiment of the invention, wherein the coated regions of the tabbing ribbons comprise at least the regions of the tabbing ribbons that are exposed to incident light on a front side of the solar panel.

[0043] Having the coated regions of the tabbing ribbons comprising at least the sections of the tabbing ribbons that are exposed to incident light on the front side of the solar panel is advantageous in that coating of these sections may impose a visual change in the appearance of the solar panel. The visual change in appearance may arise due to a lower reflectance of the coated tabbing ribbon as compared to a clean tabbing ribbon or a tabbing ribbon comprising a soldering layer. [0044] According to an embodiment of the invention, the solar cells are silicon based.

[0045] The use of silicon is advantageous in that silicon is an abundant material with a low cost.

[0046] According to an embodiment of the invention, the solar cells are mono- crystalline silicon solar cells. [0047] According to an embodiment of the invention, the solar cells are poly- crystalline silicon solar cells.

[0048] A polycrystalline silicon solar cell is cheaper to manufacture than a monocrystalline solar cell, however a monocrystalline silicon solar cell may still present a greater efficiency in converting photons into electrical energy. [0049] According to an embodiment of the invention, the solar cells are quasi-mono- crystalline silicon solar cells containing 60-99% mono-crystalline silicon.

[0050] A quasi-mono-crystalline silicon solar cell represents a compromise between the performance of a monocrystalline silicon solar cell and the manufacturing cost of a poly crystalline silicon solar cell. [0051] According to an embodiment of the invention, the solar cell surface comprises conically shaped nanostructures manufactured by means of maskless reactive ion etching (RIE).

[0052] Texturizing the silicon by reactive ion etching (RIE) such that conically shaped nanostructures becomes present on the exposed surface of the silicon solar cell is advantageous in that the reflectance of the silicon solar cell may be further reduced.

[0053] Alternatively, other types of solar cells may be used within the scope of the invention.

[0054] According to an embodiment of the invention, the spectrum comprises wavelengths in the range from 300 nm to 800 nm.

[0055] According to an embodiment of the invention, the inorganic coating comprises metal chalcogenides such as metal oxides, metal sulfides or mixtures thereof.

[0056] According to an embodiment of the invention, the inorganic coating comprises metal oxides.

[0057] According to an embodiment of the invention, the inorganic coating consists of metal oxides.

[0058] According to an embodiment of the invention, the inorganic coating comprises metal sulfides. [0059] According to an embodiment of the invention, the inorganic coating consists of metal sulfides.

[0060] According to an embodiment of the invention, the inorganic coating comprises copper oxide.

[0061] One advantage of the above embodiment may be that the inorganic coating comprises copper oxide may be particularly suited within the present invention for obtaining a reflectance of light below 10%, such as below 5%. [0062] The copper oxide coating may be applied as a separate layer of copper oxide on the tabbing ribbon, or the coating may be formed by treating the surface of the tabbing ribbon.

[0063] According to an embodiment of the invention, the inorganic coating consists of copper oxide.

[0064] According to an embodiment of the invention, the inorganic coating comprises a combination of copper oxide and zinc oxide.

[0065] One advantage of the above embodiment may be that the inorganic coating comprises a combination of copper oxide and zinc oxide may be particularly suited within the present invention for obtaining a reflectance of light below 10%, such as below 5%.

[0066] According to an embodiment of the invention, the inorganic coating consists of a combination of copper oxide and zinc oxide.

[0067] According to an embodiment of the invention, the inorganic coating comprises copper oxide or a combination of copper oxide and zinc oxide.

[0068] According to an embodiment of the invention, the inorganic coating comprises one or more selected from Cu, NiMo, ZnCu, NiCu, NiZn, Nickel -Zinc sulfides, Nickel oxides, Nickel sulfides, Zinc oxides, Zinc sulfides, Mo3(P04)2, Molybdenum oxides, Molybdenum sulfides, NiCoZn, NiCuCo, Cobalt oxides, Cobalt sulfides, Copper oxides, Copper sulfides, Lead oxides, Lead sulfides, Tin oxides, Tin sulfides, Silver oxides, Silver sulfides or mixtures of any of these. According to an embodiment of the invention, any of these inorganic coatings may be disposed on top of a Copper coating or a Zinc coating.

[0069] According to an embodiment of the invention, the inorganic coating comprises metal oxides other than Si02, Ti02, A1203 or metal sulfides.

[0070] According to an embodiment of the invention, the inorganic coating has a thickness below 5 micrometer. [0071] According to an embodiment of the invention, the inorganic coating has a thickness between 0.01 and 5 micrometer, such as between 0.05 and 5 micrometer, such as between 0.1 and 5 micrometer, such as 0.15 and 5 micrometer or such as between 0.1 and 3 micrometer.The thickness of the inorganic coating may vary depending on the specific circumstances. For example, the coating material and the surface structure of the coating facing the incident light may have a significant impact on the necessary coating thickness. In this context, the necessary coating thickness is that needed to obtain a reflectance of incident light below 10 % according to the invention, such as below 5%. [0072] According to an embodiment of the invention, the coating has a thickness above 200 nanometers.

[0073] Having a thickness of the coating above 200 nm is advantageous in that the coating becomes visible to a person.

[0074] According to an embodiment of the invention the inorganic coating comprises a layer of Zn having a thickness between 200 nanometers and 20 micrometers, such as between 400nm and 10 micrometers, such as between 600 nanometers and 5 micrometers and a layer of Cu having a thickness between 200 nm and 2 micrometers, such as between 200 nanometers and 1 micrometer. It is not to be understood that the layer of Cu is a coherent layer disposed on top of the layer of Zn, since the layer of Cu is a conversion layer.

[0075] According to an embodiment of the invention, the tabbing ribbons comprises tabbing ribbons attached to a bus bar of a solar cell and further attached to a back side of another solar cell.

[0076] For front contacted solar cells, attachment of tabbing ribbons between the bus bars on the front side of a solar cell and the back side of another solar cell is advantageous in that the electrically negative side of the one solar cell is connected to the electrically positive backside of the other solar cell. [0077] Connecting adjacent solar cells of a solar panel in series by the use tabbing ribbons allows for increasing the solar cell voltage by increasing the number of solar cells that are connected in series.

[0078] The attachment of the tabbing ribbon to the back side of a solar cell may be an attachment to an electrically conductive back plate of the solar cell.

[0079] According to an embodiment of the invention, each tabbing ribbon which is attached to a bus bar of a solar cell is further attached to a back side of another solar cell.

[0080] According to an embodiment of the invention, the attachment sites comprises a soldering layer.

[0081] Having a soldering layer on the attachment sites of the tabbing ribbons is advantageous in that the tabbing ribbons may be soldered to a bus bar or an electrically conductive back plate of a solar cell.

[0082] According to an embodiment of the invention, the tabbing ribbons comprises a soldering layer and said inorganic coating is disposed on top of said soldering layer.

[0083] Thus in the above embodiment the tabbing ribbons comprises a soldering layer disposed on both the coated region and the region free of said inorganic coating.

[0084] According to an embodiment of the invention, the attachment sites comprises a soldering layer and wherein the coated region is free of soldering. [0085] Having soldering at the attachment sites only is advantageous in that this represents a saving in the amount of soldering material needed.

[0086] The invention further relates to a method of manufacturing a solar panel comprising the steps of providing a plurality of solar cells, each solar cell comprising at least one bus bar; providing a plurality of tabbing ribbons; selectively applying an inorganic coating onto at least some of said tabbing ribbons to form a coated region and a region free of said inorganic coating, the inorganic coating providing less than 10 % reflectance of light, incident on the inorganic coating at a normal angle of incidence, in a given spectrum, said spectrum comprising wavelengths in the range from 400 nm to 700 nm; attaching said region free of coating to a bus bar of a solar cell; [0087] According to an embodiment of the invention, the inorganic coating providing less than 10 % reflectance of light, incident on the inorganic coating at a normal angle of incidence, in a given spectrum, said spectrum comprising wavelengths in the range from 400 nm to 700 nm, here understood as less than 10 % to 5% reflectance of light or less than 5 % reflectance of light, incident on the inorganic coating at a normal angle of incidence, in a given spectrum, said spectrum comprising wavelengths in the range from 400 nm to 700 nm.

[0088] According to an embodiment of the invention, the inorganic coating provides less than 10 % reflectance of light.

[0089] According to an embodiment of the invention, the inorganic coating provides less than 5 % reflectance of light.

[0090] According to an embodiment of the invention, the inorganic coating provides less than 10 % to 5 % reflectance of light.

[0091] According to an embodiment of the invention, the step of selectively applying the inorganic coating comprises applying the inorganic coating to the coated regions. [0092] By applying the inorganic coating to the coated regions, it is understood that an inorganic coating is applied on the tabbing ribbon at the regions, which when the inorganic coating is applied on top of, constitute the coated regions. Thus, the step may be understood as applying the inorganic coating to form the coated region. In some embodiments these coated regions are formed by the application of the coating itself, whereas in other embodiments the forming of the coating regions involves applying a coating and subsequently removing a part of the coating, such that coated regions remain. [0093] According to an embodiment of the invention, the step of selectively applying the inorganic coating comprises applying said inorganic coating onto said tabbing ribbons and subsequently selectively removing a part of said inorganic coating to form a region free of said inorganic coating, the remaining inorganic coating forming the coated region.

[0094] According to an embodiment of the invention the step of selectively applying the inorganic coating is performed using a machine for production of tabbing ribbons.

[0095] The invention further relates to a machine for production of tabbing ribbons, comprising a tabbing ribbon feeding mechanism, a coating application arrangement, a coating removal arrangement, a tabbing ribbon collecting mechanism, a guiding system and a control unit, wherein said guiding mechanism is configured to transfer a tabbing ribbon from said tabbing ribbon feeding mechanism, through said coating application arrangement and through said coating removal arrangement to said tabbing ribbon collecting mechanism to produce a processed tabbing ribbon, wherein said coating application arrangement is configured to apply a layer of coating to said tabbing ribbon, wherein said coating removal arrangement is configured to selectively remove at least parts of said coating in response to control signals from said control unit, wherein said processed tabbing ribbon is characterized by comprising coated regions providing less than 10 % reflectance of light, incident on the coated regions at a normal angle of incidence, in a given spectrum, said spectrum comprising wavelengths in the range from 400 nm to 700 nm.

[0096] Thereby is achieved an advantageous machine which allows for a processing of a tabbing ribbon in an automated way. The processed tabbing ribbon may comprise a plurality of individual tabbing ribbons adjoined to form an extended tabbing ribbon with a length exceeding the length of typical tabbing ribbon sections used for the assembly of solar panels. By the machine selectively removing at least parts of said coating is achieved an advantageous effect in that a processed tabbing ribbon having both coated and uncoated regions is achieved. Thus, the processed tabbing ribbon may be used for the assembly of a solar panel, after e.g. cutting the processed tabbing ribbons into desired pieces of tabbing ribbon. [0097] In an embodiment the tabbing ribbons are for a solar panel, i.e. the machine is suitable for production of tabbing ribbons for a solar panel.

[0098] By a coating application arrangement is understood an arrangement capable of applying a coating to a tabbing ribbon. The coating application arrangement may be an open container, such as a vessel, containing coating material in liquid form.

[0099] By a coating removal arrangement is understood an arrangement capable of removing or stripping a tabbing ribbon from coating. In an embodiment of the invention, the coating removal arrangement is a wet-blasting unit.

[0100] In an embodiment of the invention the processed tabbing ribbon is characterized by comprising coated regions providing less than 5 % reflectance of light, incident on the coated regions at a normal angle of incidence, in a given spectrum, said spectrum comprising wavelengths in the range from 400 nm to 700 nm.

[0101] In an embodiment of the invention said coating application arrangement is configured to apply a coating in one or more steps. The coating application arrangement may comprise means for applying a coating. Examples of such means are PVD (physical Vapor Deposition), CVD (Chemical Vapor Deposition) or other techniques for formation of a coating from liquid phase.

[0102] Application of coating in one or more steps is advantageous in that the machine for production of tabbing ribbons is capable of producing a great variety of different coatings. Application of coating may be performed in one or more steps depending on the coating material. Some coatings may consist of a single layer of coating which can be applied in a single step, other coatings are multi-layered coatings which require sequential coating with different coating materials, and some coatings may be realized through a chemical reaction between two coating materials. [0103] In an embodiment of the invention said machine for production of tabbing ribbons comprises a further processing arrangement.

[0104] By a further processing arrangement is understood an arrangement which is used in combination with the coating application arrangement to produce a coating. In an embodiment, the further processing arrangement is a further coating application arrangement which may be useful for applying an additional layer of coating using a similar technique of coating a tabbing ribbon. In another embodiment, the further processing arrangement is distinct to the coating application arrangement and utilizes a different technique of processing. As an example, the coating application arrangement may utilize the technique of electroplating and the further processing arrangement may utilize the technique of ion exchange, which may be used for a coating material comprising ZnCu.

[0105] In an embodiment of the invention the machine for production of tabbing ribbons comprises a further processing arrangement which is configured to process said tabbing ribbon to provide for said reflectance of light.

[0106] When a specific coating requires a further processing arrangement, e.g. a coating requiring more than one processing step, the coated tabbing ribbon obtains the desired reflectance characteristics after processing by the further processing arrangement.

[0107] According to an embodiment of the invention, said tabbing ribbon feeding mechanism (TFM) is configured to feed said tabbing ribbon to said guiding system.

[0108] According to an embodiment of the invention, the tabbing ribbon feeding mechanism is motorized. [0109] According to an embodiment of the invention said tabbing ribbon collecting mechanism is configured to collect a processed tabbing ribbon from said guiding system.

[0110] According to an embodiment of the invention, the tabbing ribbon collecting mechanism is motorized. [0111] According to an embodiment of the invention said tabbing ribbon feeding mechanism and/or said tabbing ribbon collecting mechanism comprises a roll for storing said tabbing ribbon and/or said processed tabbing ribbon. [0112] According to an embodiment of the invention said tabbing ribbon collecting mechanism comprises means for dragging said tabbing ribbon from said tabbing ribbon feeding mechanism to said tabbing ribbon collecting mechanism.

[0113] According to an embodiment of the invention said feeding of said tabbing ribbon by said tabbing ribbon feeding mechanism is synchronized with said collecting of said processed tabbing ribbon by said tabbing ribbon collecting mechanism.

[0114] According to an embodiment of the invention, said synchronization is controlled by said control unit transmitting or sending control signals to the tabbing ribbon feeding mechanism and/or tabbing ribbon collecting mechanism. As an example, the tabbing ribbon feeding mechanism may be a motorized roll and the tabbing ribbon collecting mechanism may also be a motorized roll. The synchronization is achieved by careful of the rotation of the two rolls by motors driving the rotation of the rolls.

[0115] According to an embodiment of the invention said guiding system comprises a pulley system.

[0116] According to an embodiment of the invention said machine for production of tabbing ribbons further comprises a tabbing ribbon rinsing mechanism configured to rinse the tabbing ribbon, and a tabbing ribbon drying mechanism configured to dry said processed tabbing ribbon. [0117] The invention further relates to a terrestrial object comprising a solar panel as described in any of the above embodiments.

[0118] By a terrestrial object is understood an object on or in close proximity to earth. The terrestrial object may be an object which is associated with an energy consumption, such as a building having a consumption of electrical energy, or an electric car consuming electric energy when driving.

[0119] According to an embodiment of the invention said terrestrial object is a building. [0120] By integrating the solar panel into a building is achieved a building where the solar panel may become difficult to see when compared to the surrounding building. In this context, the solar panel may be referred to as a building integrated photovoltaic (BIPV) panel. When the solar panel becomes difficult to see or aesthetically integrated into a building, an aesthetically pleasing building may be realized.

[0121] According to an embodiment said building is selected from the list consisting of residential buildings, commercial buildings and industrial buildings.

[0122] Examples of residential buildings are single family houses such as villas or terraced houses and multi-family housings such as apartment buildings. Examples of commercial buildings are office buildings, retail buildings such as shops, shopping centers and retail outlets, and hotels such as full service hotels, motels and resorts. Examples of industrial buildings are manufacturing buildings such as light manufacturing buildings and heavy manufacturing buildings, warehouse buildings such as bulk warehouses and warehouse stores, and distribution centers such as container terminals and truck terminals.

[0123] According to another embodiment of the invention said terrestrial object is a vehicle.

[0124] According to an embodiment said vehicle is a motorized vehicle, which may be a motorized vehicle selected from the list consisting of cars, trucks, lorries, busses, locomotives, tractors, motorcycles, boats, and ferries.

[0125] According to another embodiment said vehicle is a non-motorized vehicle.

[0126] Examples of non-motorized vehicles are bicycles, railway carriages, trailers and gliders. The drawings

[0127] Various embodiments of the invention will in the following be described with reference to the drawings where fig. 1 illustrates a solar cell 1, fig. 2 illustrates a solar panel 10 comprising a plurality of solar cells 1, fig. 3 illustrates the connection of solar cells 1 using tabbing ribbons 4, fig. 4 illustrates a tabbing ribbon 4 attached to different sides of a solar cell 1, fig. 5 illustrates a tabbing ribbon 4 comprising a coated region 21 and a coating-free region 20, fig. 6 illustrates a tabbing ribbon 4 comprising a soldering layer 23 and a coating 24, fig. 7 illustrates a tabbing ribbon 4 comprising a soldering layer 23 and a coating 24, wherein the coating 24 is disposed on top of the soldering layer 23, fig. 8 illustrates real measurements of reflectance performed on tabbing ribbons 4 that are treated in different ways, fig. 9 illustrates a method of applying a coating 24 to a tabbing ribbon 4, fig. 10 illustrates a cross-sectional view of a solar cell 1 attached to tabbing ribbons 4, figs. 1 la-c illustrate a machine for production of tabbing ribbons, and figs. l2a-d illustrate terrestrial objects comprising a solar panel 10. Detailed description

[0128] Fig. 1 illustrates a front view of a front-contacted solar cell 1. The purpose of the solar cell 1 is to convert photons into an electrical current by the creation of electron-hole pairs. [0129] The cell 1 consists of two types of electric contacts on the front side; bus bars

2 and fingers 3. These contacts may be screen printed onto the surface of the cell 1. The solar cell 1 further comprises an electric contact on the back side (7, not shown here). The front side and back side of the solar cell 1 have different electrical polarity. Typically, the front side of a front-contacted solar cell is the negative pole and the backside of the solar cell is the positive pole.

[0130] The fingers 3, which may also be referred to as grid-fingers are thin metal contacts placed parallel to one another along the entire width of the solar cell 1. The purpose of the fingers 3 is to collect electrons generated by the solar cell upon exposure to light. [0131] Perpendicular to the fingers 3 are a number of bus bars 2 arranged to transmit the electrons collected by the fingers 3 away from the cell. The width of the bus bars 2 may be of the order of a few millimeters, for example 1-2 millimeters, and the width of the fingers 3 is correspondingly even smaller, for example below 200 micrometers.

[0132] The solar cell 1 may comprise any number of bus bars 2. The number of bus bars 2 used for a solar cell 1 is chosen based on considerations of cost and efficiency. A greater amount of bus bars 2 results in a reduced distance between bus bars 2 of the solar cell 1. A shorter distance between bus bars 2 generally results in less electrical resistance through the fingers 3, because the electrons collected by the fingers 3 have to travel a shorter distance through the finger 3 before arriving at the nearest positioned bus bar 2.

[0133] However, increasing the bus bar surface coverage decreases the cell area that is exposed to sun light and therefore reduces the number of electrons generated. Thus, in addition to choosing the number of bus bars 2, solar cell manufacturers must also consider the width of the bus bars 2. Increasing the amount of bus bars 2 may present a cost-effective approach towards solar cell production, since the bus bars 2 may be designed even narrower as a result of the generated current being distributed across an increasing amount of bus bars 2, and with a correspondingly smaller current passing through each bus bar 2.

[0134] Fig. 2 illustrates front view of a solar panel 10 comprising front-contacted solar cells 1. The solar panel 10 shown on fig. 2 includes nine individual solar cells 1 configured in a three-by-three configuration. Each column (disposed longitudinally in a direction orthogonal to the two end-members 5) of three solar cells 1 is connected in series by tabbing ribbons 4, and all three columns of serial-connected solar cells 1 are then connected to each other by a bussing ribbon 5; one bussing ribbon 5 at each end of the solar panel 10. The bussing ribbon 5 may be made of the same material as the tabbing ribbon 4.

[0135] The tabbing ribbons 4 are configured to connect a negative pole of a solar cell 1 to a positive pole of another adjacent solar cell 1. The solar cells 1 in a column are thereby connected electrically in series by successive connections of the front side of one solar cell to the back side of the adjacent solar cell, as seen on fig. 3.

[0136] By electrically connecting solar cells in series the output voltage of the solar panel may be configured, because the voltage is additive when wiring solar cells in series. As an example, connecting five solar cells, each rated at 0.5 volts and 3 amperes, results in the entire array outputting 2.5 volts at 3 amperes. That is, the current is constant throughout the array of serially connected solar cells, as opposed to the case of parallel connected solar cells where the voltage is constant and the current is additive. Thus by increasing the amount of solar cells 1 in a serial connection, a greater output voltage may be achieved.

[0137] The tabbing ribbons 4 are attached to the bus bars 2 (not shown on the figure) on the front side of the solar cells 1. In fig. 2, the width of the tabbing ribbons 4 are substantially equal to the width of the bus bars 2, thus blocking the bus bars 2 in the front view of the solar panel 10. A tabbing ribbon 4 is a flat metal string substantially made of copper. For example, the tabbing ribbon may comprise 99.99 % copper. A cross section of a tabbing ribbon 4 may show a width of the order of 1-2 mm and a height/thickness of the order of a few tenths of a millimeter, such as 0.2 millimeters. [0138] Fig. 3 illustrates a side view of one of the columns of solar cells 1 from fig.

2. The figure shows three solar cells 1 connected by two tabbing ribbons 4. The left side tabbing ribbon 4 connects the positive pole of the left most solar cell 1 to the negative pole of the middle solar cell 1, and the right side tabbing ribbon 4 connects the positive pole of the middle solar cell 1 to the negative pole of the right most solar cell 1. Thus as seen in the figure, the tabbing ribbons are not continuous strings extending across the entire solar panel 10, but rather strips connecting only adjacent solar cells 1.

[0139] Fig. 4 illustrates a tabbing ribbon 4 connecting two adjacent solar cells 1 of a solar panel 10. The tabbing ribbon 4 connects a back side (BS) of a solar cell 1 to a front side (FS) of another solar cell 1. In this connection, a first section of the tabbing ribbon 4 is disposed in a hidden region (HR) at the back side (BS) of the left most solar cell 1, and a second section of the tabbing ribbon 4 is disposed in an exposed region (ER) extending across the front side FS of the left most cell 1 and the gap between the two solar cells 1. The front side FS of a solar cell 1 is the side of the solar cell which is arranged to receive incoming photons from a light source, such as the sun.

[0140] The tabbing ribbon 4 is attached to the solar cells 1 at attachment sites 6 of the tabbing ribbon 4. These attachment sites 6 are sites where the tabbing ribbon 4 is attached to the bus bars 2 of the solar cells 1. The bus bars may be attached by any means of attachment suitable for conducting an electrical current. As an example, the tabbing ribbon 4 may be attached to the bus bar 2 by means of soldering or by means of gluing or bonding, such as gluing with an electrical conductive adhesive. The electrical conductive adhesive may either be isotropic or anisotropic. An isotropic conductive adhesive (abbreviated ICA) is electrical conductive in all directions, whereas an anisotropic conductive adhesive (abbreviated ACA) contains special conductive particles, with a size in the micrometer range, that only conduct electricity in one direction.

[0141] Although fig. 4 only illustrates two attachment sites 6, this is not construed as there can only be one attachment site 6 on the tabbing ribbon 4. In principle, the tabbing ribbon 4 may comprise a plurality of attachment sites at each end, such that for example the tabbing ribbon 4 is attached to the front side FS or the back side BS at a number of positions along the tabbing ribbon. This could be the case if the tabbing ribbon 4 is spot welded onto the frontside FS or back side BS at several spots.

[0142] Fig. 5 illustrates a side view of a tabbing ribbon 4 that is bent into a configuration suitable to attach onto the front side FS of a solar cell 1 and attach onto the back side BS of another solar cell 1. One attachment site 6 is indicated on the figure. This attachment site 6 may be adapted to attach onto the bus bars 2 on the front side FS of a solar cell 1.

[0143] Fig. 5 further illustrates that the tabbing ribbon 4 comprises a coated region 20 and a coating-free region 21. The coated region may comprise a low reflectance coating 24, such as an inorganic coating. As an example, the coating 24 may only have a thickness of a few micrometers (not drawn to scale), such as one micrometer. As seen in the figure, the coated region 21 extends along the entire exposed region ER of the tabbing ribbon 4, such that the coating 24 is also exposed along same exposed region ER of the tabbing ribbon 4.

[0144] The inorganic coating has a low reflectance of light at normal incidence, meaning that only a small fraction of incoming light is reflected by the coating. This ensures that the visible contrast between the tabbing ribbon 4 is low compared to the solar cell 1 itself. A low contrast between the solar cell 1 and the coating 24 of the tabbing ribbon 4 ensures that the solar panel 10 will appear homogeneous from the front side FS of the solar cells (1).

[0145] Fig. 6 illustrates a cross-sectional view of a section of an example of a tabbing ribbon 4. As seen from the figure, the tabbing ribbon 4 is a strip comprising a tabbing ribbon core 22, which may comprise copper of great purity, such as 99.99 % copper. In this context, having a high content of copper is generally considered advantageous, as this facilitates having a high conductivity at a reasonably pricing. Thus, in principle 100% copper would often be desirable, whereas certain practical considerations, may put the actual concentration of copper below 100%. As seen, the tabbing ribbon comprises a coating-free region 20 and a coated region 21 comprising a coating 24. In the figure, the coating-free region 20 comprises the tabbing ribbon core 22 and a soldering layer 23 disposed on top of the tabbing ribbon core 22. The position of the solder layer 23 on the tabbing ribbon core 22 may correspond to the position of an attachment site 6 (see for example fig. 4, where an attachment site is disposed on the tabbing ribbon at the back side of a solar cell). The coated region 21 comprises a coating 24 disposed directly on top of the tabbing ribbon core 22, and as seen in the figure, the coated region 21 may further comprise an additional soldering layer 23 disposed directly on top of the tabbing ribbon core 22, but on the opposite site to the coating 24. This soldering layer 23 on the coated region 21 may correspond to a position on the tabbing ribbon 4 where an attachment site 6 is present.

[0146] As an illustrative example, the coated region 21 of the tabbing ribbon 4 in fig. 6 may be positioned on the front side FS of a solar cell 1, such that soldering layer 23 is positioned on top of a bus bar 2 (not shown in the figure) of a solar cell 1, and soldered onto it. The coating-free region 20 is stringed underneath an adjacent solar cell , such that the solder layer 23 of the coating-free region 20 is disposed on the back side BS of the adjacent solar cell 1, and soldered onto the electrically conductive back plate 7 of this solar cell 1.

[0147] This illustrates a possible cost effective approach of producing a tabbing ribbon 4 with low reflectance, since the coating 24 is only applied where needed, and a solder layer 23 is also only applied where needed.

[0148] Fig. 7 illustrates another example of a tabbing ribbon 4, comprising a tabbing ribbon core 22, onto which a solder layer 23 is applied. The solder layer 23 extends along the entire tabbing ribbon 4, both across the coating-free region 20 and the coated region 21. The coated region 21, comprises an additional coating 24 disposed on top of the solder layer 23. [0149] As an illustrative example, the coated region 21 of the tabbing ribbon 4 in fig. 7 may be positioned on the front side FS of a solar cell 1, such that soldering layer 23 is positioned on top of a bus bar 2 (not shown in the figure) of a solar cell 1, and soldered onto it. The coating-free region 20 is stringed underneath an adjacent solar cell , such that the solder layer 23 of the coating-free region 20 is disposed on the back side BS of the adjacent solar cell 1, and soldered onto the electrically conductive back plate 7 of this solar cell 1.

[0150] As seen in both figs. 6 and 7, the solder layer 23 may be disposed on top of the tabbing ribbon core 22 at any given position along the tabbing ribbon 4, and the coating 24 may similarly be disposed on top of the tabbing ribbon core 22 at any given position along the tabbing ribbon 4, or alternatively on top of a solder layer 23.

[0151] A number of reflectance measurements have been performed on tabbing ribbons comprising different combinations of materials (soldering and/or coatings). These different combinations of materials are shown in table 1 below. Measurements on these tabbing ribbons is presented below.

[0152] Tabbing ribbons (TR1-TR5) with five different combinations of materials (soldering and/or coatings) where manufactured according to table 1. TR1 represents a tabbing ribbon with a soldering layer on top of the copper core. TR2 represents a tabbing ribbon consisting of a copper core only.

Table 1. Tabbing ribbons with different coatings TR3 and TR4 represents a tabbing ribbon where respectively a NiCuCo coating and a NiZnS coating has been applied on top of a soldering layer, and the soldering layer is disposed on top of the copper core. TR5 represents a tabbing ribbon where a copper oxide (CuO) coating has been applied directly on top of copper core. [0153] Fig. 8 shows reflectance measurements of the five tabbing ribbons as exemplified in table 1. All reflectance measurements have been conducted with light comprising wavelengths 400 nm (nanometer) to 800 nm. For the measurements an integrated sphere was used. The measurements are measurements of diffuse reflectance for an incident angle of 0 degrees to the sphere, using a standard white plate for correcting baseline. First standard white plates at each exit window on both the sample side (with 0 degree incidence to the sphere) and the reference side (with 8 degree incidence to the sphere) were set to correct the baseline. After correcting baseline, the standard on the sample side was replaced by a sample and the measurements were carried out. [0154] The tabbing ribbon labeled TR1 had a reflectance above 50 percent of light in the range from 400 nm to 800 nm. Such a high reflectance means that the tabbing ribbon 4 becomes clearly visible when exposed to light. As a comparison, untreated tabbing ribbon TR2, had a reflectance below 40 percent in the same range of 400 nm to 800 nm. This clearly shows illustrates that the soldering layer is ideally not suited as the upmost layer of the tabbing ribbon in the regions where the tabbing ribbon is exposed to light.

[0155] The next three measurements (TR3-TR5) clearly shows how an inorganic coating may reduce the reflectance of a tabbing ribbon. Both TR3 and TR4 have a significantly lower reflectance than TR1, showing that application of an inorganic coating on top of a soldering layer clearly changes the reflectance. For TR3, the reflectance is significantly reduced to about 10 percent in the range from 400 nm to 800 nm, and for TR4, the reflectance is reduced to about 4 percent in the same range from 400 nm to 800 nm. [0156] TR5 has a slightly lower reflectance than TR4 in the range from 400 nm to 700 nm, however the reflectance is found to increase to about 10 percent in the range from 700 nm to 800 nm.

[0157] In all, fig. 8 shows that disposing an inorganic coating on top of a tabbing ribbon (with or without soldering) significantly decreases the reflectance of the tabbing ribbon 4 in the light spectrum comprising wavelengths in the range of 400 nm to 800 nm.

[0158] Fig. 9 illustrates a method of applying an inorganic coating to atabbing ribbon 4. The tabbing ribbon 4 may be fed from a starting station onto a cleaning station 31, preparing the tabbing wire 4 for the first treatment occurring at an electroplating station

32. The electroplating station 32 deposits a metal such as for example zinc (Zn) onto the tabbing wire 4.

[0159] Afterwards the tabbing ribbon 4 is fed through a first rinsing station 33 before receiving a second treatment at the blackening station 34, where the coating 24 of the tabbing ribbon 4 is finished. As an example, the blackening station may perform an ion exchange reaction with copper (Cu).

[0160] Afterwards the tabbing ribbon 4 passes a coating removal station 35, where regions of coating 24 may be removed selectively, such that attachment sites 6 may be exposed, since an inorganic coating 24 with low reflectance is ideally not suited as a means of soldering as well. The coating removal station 35 may be arranged to remove coating 24 of a tabbing ribbon 4 by any suitable means, such as for example through wet blasting or by use of a laser, such as a femtosecond laser.

[0161] Afterwards, the tabbing ribbon 4 is passed onto a second rinsing station 36, before reaching a drying station 37 positioned adjacent to a finishing station 38, where the treated tabbing ribbon 4 is collected.

[0162] The end product of this procedure is a roll of continuous tabbing wire 4, and before application in a solar panel, the continuous tabbing wire 4 is cut into strips suitable for attaching to solar cells 1, as seen in figs. 3 and 4 for example. Fig. 10 illustrates a cross-sectional view of a solar cell 1 in contact with tabbing ribbons 4.. Central to the solar cell l is a semi-conductive material, such as silicon (Si) or gallium arsenide (GaAs). In order to convert photon power into electrical power, a so-called pn junction is formed within the semi- conductive material. A pn junction, also referred to as a metallurgical junction, is an interface separating an n-type and a p-type region of the semiconductor. The n-type region N is a region of increased electron concentration compared to the intrinsic semi-conductive material, and the p-type region P is a region of reduced electron density compared to the intrinsic semi- conductive material (or commonly known in the field of semi-conductors as a region with greater density of holes). Electron-hole pairs are generated within a space-charge region of the pn junction PN by incident photons, and swept out producing a photocurrent.

[0163] The doping of the semi-conductor material into n- and p-type regions may be realized through e.g. diffusion of phosphorus oxy-chloride (POCb) or boron. Alternatively to diffusion doping, laser doping may be used as well. In laser doping, a laser locally melts the semi-conductive material while dopant atoms in the vicinity diffuse in.

[0164] In order to extract the photocurrent, a number of electrical contacts is put in contact with the semi-conductive material. The n-type region N is contacted by bus bars 2 and fingers 3 (not shown on the figure) whereas the p-type region P is in electric contact with an electrically conductive plate 7. Any number of fingers 3 and bus bars 2 may be used, however at least one bus bar 2 is needed. Prior to completion of the solar panel production, a number of tabbing ribbons 4 are attached to the metal contacts (2; 7). [0165] In fig. 10 it is illustrated how the tabbing ribbons 4 are attached on top of the bus bars 2 of the solar cell 1. The width Wt of the tabbing bars 4 are preferably equal to the width Wb of the bus bars 2. If the width of the tabbing bars 4 extend beyond the width of the bus bars 2, too much frontal area of the solar cell 1 is blocked resulting in a lower power output of the cell, and on the contrary, an inadequate transfer of photocurrent to the tabbing bars 4 may result from having tabbing bars 4 that are narrower than the bus bars 2.

[0166] The bus bars 2 may be put on the solar cell 1 by screen printing of silver (Ag) on top of an anti-reflective coating AC. The anti-reflective coating AC is used to increase the transmittance of light onto the solar cell 1, and may be realized through plasma enhanced chemical vapor deposition (PECVD) of silicon nitride (SiN_x:H). After screen printing of contacts a curing/baking process is performed. During this process, the screen printed contacts 2 perforates the anti-reflective coating AC and contacts the semi-conductive material. After attachment of tabbing ribbons 4, the plurality of solar cells 1 making up the solar panel 1 may be encapsulated in a protective film, such as an ethylene vinyl acetate (EVA) film (not shown on the figure) to extend the durability of the solar panel 10, also in difficult weather circumstances, such as high temperatures and high humidity. For additional protection, a glass layer may be installed on the front of the solar panel to further protect the panel from the surrounding elements and from impacts with solid objects, such as fallout from trees.

[0167] The N-type layer N of the semi conductive material may additionally comprise an upper surface that is textured, such that the reflectance of the semi conductive material is reduced even further. As an example, the N-type layer may be textured by a reactive ion etching (RIE) process, such that conically shaped nanostructures are dispersed on the upper surface of the semi conductive material. The RIE-process is a maskless process using SF6 and 02 plasma. Such a RIE-texturing process is applicable to most semiconductor materials suitable for solar cells, and will render the appearance of the solar cell black, since only very little light is reflected on the material.

[0168] The conically shaped nanostructures may have a base width of a few hundred nanometers, for example between 100 nanometers and 200 nanometers or above 200 nanometers, and a height of some hundred nanometers, for example between 200 nm and 450 nm. The pitch of the nanostructures (distance between nanostructures) may be a few hundred nanometers, for example between 200 nanometers and 400 nanometers. [0169] By combining tabbing ribbons 4 with a solar cell 1 comprising an RIE- texturing as described above may be particular advantageous, in that the entire solar panel may appear black to an observer. Although, an advantageous combination, the tabbing ribbons 4 may also be used within the context of the present invention. [0170] Figs. 1 la-c illustrate embodiments of the invention.

[0171] Fig. l la illustrates how various sections of a machine 40 for production of tabbing ribbons are arranged. The machine 40 comprises a tabbing ribbon feeding mechanism TFM which is configured to feed a guiding system (not shown) with a tabbing ribbon which is about to be processed by the machine 40, such that a processed tabbing ribbon is created. In this sense the processed tabbing ribbon may have a length greater than the typical lengths of individual tabbing ribbons 4 used in a solar panel 10. In other words, the processed tabbing ribbon may consist of a plurality of individual tabbing ribbons 4 which are adjoined. Thus, a plurality of tabbing ribbons 4 used for a solar panel 10 may be extracted from a processed tabbing ribbon by for example cutting a processed tabbing ribbon into individual tabbing ribbons 4. The tabbing ribbon which is fed by the tabbing ribbon feeding mechanism TFM is handled by the guiding system which is configured to direct the tabbing ribbon through the machine 40.

[0172] After being fed by the tabbing ribbon feeding mechanism TFM, the tabbing ribbon is transferred, by the guiding system, to a coating application arrangement CAA which is configured to apply a coating to the tabbing ribbon. The coating application arrangement CAA may apply a coating on the entire tabbing ribbon.

[0173] Following application of a coating on the tabbing ribbon by the coating application arrangement CAA, the coated tabbing ribbon is transferred, by the guiding system, to a coating removal arrangement CRA which is configured to selectively remove the applied coating at specific locations of the coated tabbing ribbon. By selectively removing the applied coating at specific locations on the tabbing ribbons it is understood that the coating removal arrangement CRA is capable of removing coating at positions/regions along the coated tabbing ribbon which corresponds to the coating free regions 20 shown on the drawings of fig. 5 through 7.

[0174] Following the selective removal of applied coating by the coating removal arrangement CRA, the coated tabbing ribbon having coating removed selectively is transferred, by the guiding system, to a tabbing ribbon collecting mechanism TCM, which is configured to collect the processed tabbing ribbon.

[0175] Fig. 1 lb shows a machine 40 for production of tabbing ribbons, as shown in fig. 11 a, with the addition of a further processing arrangement FPA. The further processing arrangement FPA is configured to, in combination with the coating application arrangement CPA, to ensure that the tabbing ribbon is coated with an inorganic coating. Using a further processing arrangement FPA may be necessary for coatings which are obtained using more than one step.

[0176] As an example, application of a ZnCu coating requires a step of electroplating with zinc followed by ion exchange with copper. In this example, the electroplating with zinc may be performed by the coating application arrangement CAA and the ion exchange with copper may be performed by the further processing arrangement FPA. In this way, a coated tabbing ribbon is realized through a combined process performed by the coating application arrangement CAA and the further processing arrangement FPA. [0177] The further processing arrangement FPA receives a tabbing ribbon from the coating application arrangement CAA, by the guiding system, and the guiding system is used to transfer the coated tabbing ribbon from the further processing arrangement FPA to the coating removal arrangement CRA.

[0178] Fig. 1 lc shows a machine 40 for production of tabbing ribbons, as shown in fig. 1 lb with the addition of a tabbing ribbon rinsing mechanism TRM which performs a rinsing of the coated tabbing ribbon transported from the coating application arrangement, by the guiding system, and with the addition of a tabbing ribbon drying mechanism TDM which performs a drying of the tabbing ribbon which is transported from the coating removal arrangement CRA. In other embodiments, the tabbing ribbon rinsing mechanism TRM and tabbing ribbon drying mechanism TDM are disposed in other position within the machine 40.

[0179] In all the embodiments shown in figs. 1 la-c, a control unit CU is shown. The control unit is used to send control signals to the coating removal arrangement CRA, such that the coating on the tabbing ribbon may be selectively removed from positions on the coated tabbing ribbon. The control signals may be sent on the basis of pre- programmed instructions stored in a memory associated with the control unit CU.

[0180] In other embodiments, other components of the machine 40 may be controlled by the same control unit CU and/or by an auxiliary control unit. [0181] The drawing of fig. 9 also illustrate a machine 40 for production of tabbing ribbons according to an embodiment of the invention. In the context of the above description of a machine for production of tabbing ribbons, the feature 30 is a tabbing ribbon feeding mechanism in the form of a roll onto which a tabbing ribbon is stringed, the feature 38 is a tabbing ribbon collecting mechanism in the form of a roll onto which a processed tabbing ribbon is stringed, feature 32 is a coating application arrangement, feature 34 is a further processing arrangement, feature 35 is a coating removal arrangement. The drawing of this embodiment further illustrates a tabbing ribbon rinsing arrangement 36; TRA and a tabbing ribbon drying arrangement 38; TDA. The tabbing ribbon in figure 9 is transported within the machine by a guiding system in the form of a pulley system comprising a plurality of pulleys.

[0182] Figs. l2a-b illustrate embodiments of the invention.

[0183] Fig. l2a shows a building 50, such as a house, where the solar panel 10 is integrated into. In the specific drawing of fig. l2a, the solar panel is integrated into the roof of the building 50. In other embodiments, the solar panel 10 may be integrated into any other surface of the building 50.

[0184] Fig. l2b shows a vehicle 51, such as a car, where the solar panel 10 is integrated into. In the specific drawing of fig. l2b, the solar panel is integrated into the roof of the vehicle 51. In other embodiments, the solar panel 10 may be integrated into any other surface of the building 51.

[0185] List of reference signs:

1 Solar cell

2 Bus bar

3 Finger

4 Tabbing ribbon

5 Bussing ribbon

6 Attachment site

7 Electrically conductive back plate

10 Solar panel

20 Coating-free region

21 Coated region

22 Tabbing ribbon core

23 Soldering layer

24 Coating

30 Starting station

31 Cleaning station

32 Electroplating station

33 First rinsing station

34 Blackening station

35 Coating removal station

36 Second rinsing station

37 Drying station

38 Finishing station

40 Machine for production of tabbing ribbons

50 Building

51 Vehicle

FS Front side

BS Back side

ER Exposed region

HR Hidden region

TR1-TR5 Tabbing ribbon reflectance measurement curves N N-type layer

P P-type layer

PN pn junction

AC Anti-reflective coating

TFM Tabbing ribbon feeding mechanism CAA Coating application arrangement CRA Coating removal arrangement FPA Further processing arrangement TCM Tabbing ribbon collecting mechanism TRIM Tabbing ribbon rinsing mechanism TDM Tabbing ribbon drying mechanism CU Control unit

Claims

1. A solar panel (10) comprising: a plurality of solar cells (1), each solar cell (1) comprising one or more bus bars (2); and tabbing ribbons (4); wherein each solar cell (1) is connected to an attachment site (6) of one or more tabbing ribbons (4) via its one or more bus bars (2), wherein each tabbing ribbon (4), which is connected to a bus bar (2), comprises a coated region (21) comprising an inorganic coating and a region (20) free of said inorganic coating, the inorganic coating providing less than 10 % reflectance of light, incident on the inorganic coating at a normal angle of incidence, in a given spectrum, said spectrum comprising wavelengths in the range from 400 nm to 700 nm; wherein the plurality of solar cells (1) are electrically connected via the tabbing ribbons to form the solar panel (10); and wherein each attachment site (6) is located within said coating free regions of the tabbing ribbons (4).

2. A solar panel (10) according to claim 1 wherein the attachment sites (6) comprises sites where the tabbing ribbons (4) are soldered to the bus bars (2).

3. A solar panel (10) according to claim 1 or 2 wherein the inorganic coating provides less than 5 % reflectance of light in the spectrum comprising wavelengths in the range from 400 nm to 700 nm.

4. A solar panel (10) according to any of the preceding claims wherein each solar cell (1) comprises at least two bus bars (2).

5. A solar panel (10) according to any of the preceding claims wherein the inorganic coating comprises metal chalcogenides such as metal oxides, metal sulfides or mixtures thereof.

6. A solar panel (10) according to any of the preceding claims wherein the inorganic coating comprises copper oxide.

7. A solar panel (10) according to any of the preceding claims wherein the inorganic coating comprises a combination of copper oxide and zinc oxide.

8. A solar panel (10) according to any of the preceding claims wherein the inorganic coating has a thickness below 5 micrometer.

9. A solar panel (10) according to any of the preceding claims, wherein the inorganic coating has a thickness above 200 nanometers.

10. A solar panel (10) according to any of the preceding claims wherein the tabbing ribbons (4) comprises tabbing ribbons attached to a bus bar (2) of a solar cell (1) and further attached to a back side (BS) of another solar cell (1).

11. A solar panel (10) according to any of the preceding claims wherein the attachment sites (6) comprises a soldering layer.

12. A solar panel (10) according to any of the preceding claims wherein the tabbing ribbons (4) comprises a soldering layer and said inorganic coating is disposed on top of said soldering layer.

13. A solar panel (10) according to any of the preceding claims wherein the attachment sites comprise a soldering layer and wherein the coated region (21) is free of soldering.

14. A solar panel (10) according to any of the preceding claims wherein said reflectance of light is less than 5 %.

15. A solar panel (10) according to any of the preceding claims wherein said tabbing ribbons (4) are produced using a method according to any of the claims 16 to 20.

16. A method of manufacturing a solar panel (10) comprising the steps of: providing a plurality of solar cells (1), each solar cell (1) comprising at least one bus bar (2); providing a plurality of tabbing ribbons (4); selectively applying an inorganic coating onto at least some of said tabbing ribbons (4) to form a coated region (20) and a region (21) free of said inorganic coating, the inorganic coating providing less than 10 % reflectance of light, incident on the inorganic coating at a normal angle of incidence, in a given spectrum, said spectrum comprising wavelengths in the range from 400 nm to 700 nm; attaching said region (21) free of coating to a bus bar (2) of a solar cell (1);

17. The method of manufacturing a solar panel (10) according to claim 16 wherein said reflectance of light is less than 5 %.

18. The method of manufacturing a solar panel (10) according to claim 16 or 17 wherein the step of selectively applying the inorganic coating comprises applying the inorganic coating to the coated regions (21).

19. The method of manufacturing a solar panel (10) according to any of the claims 16 to 18 wherein the step of selectively applying the inorganic coating comprises applying said inorganic coating onto said tabbing ribbons and subsequently selectively removing a part of said inorganic coating to form a region (21) free of said inorganic coating, the remaining inorganic coating forming the coated region (20).

20. The method of manufacturing a solar panel (10) according to any of the claims 16 to 19 wherein the step of selectively applying the inorganic coating is performed using a machine for production of tabbing ribbons according to any of the claims 21 to 32 21. A machine (40) for production of tabbing ribbons (4) comprising a tabbing ribbon feeding mechanism (TFM), a coating application arrangement (CAA), a coating removal arrangement CRA), a tabbing ribbon collecting mechanism (TCM), a guiding system and a control unit (CU), wherein said guiding mechanism is configured to transfer a tabbing ribbon from said tabbing ribbon feeding mechanism (TFM), through said coating application arrangement (CAA) and through said coating removal arrangement (CRA), to said tabbing ribbon collecting mechanism (TCM) to produce a processed tabbing ribbon (4), wherein said coating application arrangement (CAA) is configured to apply a layer of coating to said tabbing ribbon, wherein said coating removal arrangement (CRA) is configured to selectively remove at least parts of said coating in response to control signals from said control unit (CU), wherein said processed tabbing ribbon (4) is characterized by comprising coated regions (21) providing less than 10 % reflectance of light, incident on the coated regions

(21) at a normal angle of incidence, in a given spectrum, said spectrum comprising wavelengths in the range from 400 nm to 700 nm.

22. The machine (40) for production of tabbing ribbons (4) according to claim 21 wherein said processed tabbing ribbon (4) is characterized by comprising coated regions (21) providing less than 5 % reflectance of light, incident on the coated regions (21) at a normal angle of incidence, in a given spectrum, said spectrum comprising wavelengths in the range from 400 nm to 700 nm.

23. The machine (40) for production of tabbing ribbons (4) according to claim 21 or 22 wherein said coating application arrangement is configured to apply a coating in one or more steps.

24. The machine (40) for production of tabbing ribbons (4) according to any of the claims 21 to 23 wherein said machine (40) comprises a further processing arrangement (FPA).

25. The machine (40) for production of tabbing ribbons (4) according to claim 24 wherein said further processing arrangement (FPA) is configured to process said tabbing ribbon to provide for said reflectance of light.

26. The machine (40) for production of tabbing ribbons (4) according to any of the claims 21 to 25 wherein said tabbing ribbon feeding mechanism (TFM) is configured to feed said tabbing ribbon to said guiding system.

27. The machine (40) for production of tabbing ribbons (4) according to any of the claims 21 to 26 wherein said tabbing ribbon collecting mechanism (TCM) is configured to collect a processed tabbing ribbon (4) from said guiding system.

28. The machine (40) for production of tabbing ribbons (4) according to any of the claims 21 to 27 wherein said tabbing ribbon feeding mechanism (TFM) and/or said tabbing ribbon collecting mechanism (TCM) comprises a roll for storing said tabbing ribbon and/or said processed tabbing ribbon (4).

29. The machine (40) for production of tabbing ribbons (4) according to any of the claims 21 to 28 wherein said tabbing ribbon collecting mechanism (TCM) comprises means for dragging said tabbing ribbon from said tabbing ribbon feeding mechanism (TFM) to said tabbing ribbon collecting mechanism (TCM).

30. The machine (40) for production of tabbing ribbons (4) according to any of the claims 21 to 29 wherein said feeding of said tabbing ribbon by said tabbing ribbon feeding mechanism (TFM) is synchronized with said collecting of said processed tabbing ribbon (4) by said tabbing ribbon collecting mechanism (TCM).

31. The machine (40) for production of tabbing ribbons (4) according to any of the claims 21 to 30 wherein said guiding system comprises a pulley system.

32. The machine (40) for production of tabbing ribbons (4) according to any of the claims 21 to 31 further comprising a tabbing ribbon rinsing mechanism (TRM) configured to rinse the tabbing ribbon, and a tabbing ribbon drying mechanism (TDM) configured to dry said processed tabbing ribbon (4).

33. A building comprising a solar panel (10) according to any of the claims 1 to 15.