Classifications

• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F19/00—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules
  • H10F19/80—Encapsulations or containers for integrated devices, or assemblies of multiple devices, having photovoltaic cells
  • H10F19/804—Materials of encapsulations
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F19/00—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules
  • H10F19/90—Structures for connecting between photovoltaic cells, e.g. interconnections or insulating spacers
  • H10F19/902—Structures for connecting between photovoltaic cells, e.g. interconnections or insulating spacers for series or parallel connection of photovoltaic cells
  • H10F19/906—Structures for connecting between photovoltaic cells, e.g. interconnections or insulating spacers for series or parallel connection of photovoltaic cells characterised by the materials of the structures
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F19/00—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules
  • H10F19/80—Encapsulations or containers for integrated devices, or assemblies of multiple devices, having photovoltaic cells
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F19/00—Integrated devices, or assemblies of multiple devices, comprising at least one photovoltaic cell covered by group H10F10/00, e.g. photovoltaic modules
  • H10F19/90—Structures for connecting between photovoltaic cells, e.g. interconnections or insulating spacers
  • H10F19/902—Structures for connecting between photovoltaic cells, e.g. interconnections or insulating spacers for series or parallel connection of photovoltaic cells
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
  • H10F71/00—Manufacture or treatment of devices covered by this subclass
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy

Definitions

• Solar modules for providing electrical energy from sunlight comprise an array of cells, each comprising a photovoltaic element, or substrate.
• the solar cells are typically connected so that electrical current is routed, via an electrical connector, from a front surface of one solar cell to a back surface of a second solar cell, or vice versa.
• Each of the electrical connectors comprises a plurality of electrically conductive elements (e.g. interconnecting wires) which form an electrical connection with electrodes arranged on the respective front and back surfaces of the solar cells.
• a general aim for solar cell development is to attain high conversion efficiency balanced by a need for reduced production costs. Efforts to achieve this have focussed on the electrical connections between the solar cells.
• the foil is overlaid onto the connecting wires so that the adhesive layer is brought into contact with the connecting wires. Heat and pressure are applied to the foil to thermally bond the foil to the connecting wires.
• Two solar cells are electrically connected together by a foil-electrode to form a solar cell assembly.
• a first end of the foil-wire electrode is overlaid onto the surface of a first solar cell such that the connecting wires are interposed between the foil and the solar cell surface. Heat and pressure are applied to the foil to cause the adhesive layer to thermally bond the foil to the solar cell surface.
• a second end of the foil-wire is connected to the surface of a second solar cell in the same manner. Accordingly, the foil-wire electrode provides a means of forming an electrical connection between the solar cells of a solar cell assembly.
• the peel strength is determined (e.g., measured) by 180-degree peel test according to the following method: thermally bonding the unitary film to a surface (e.g., a receiving surface) of a substrate; peeling the unitary film from the substrate according to Standard Test Method ASTM D903 to provide a peel-force trace; and determining, from the peel-force trace, that the unitary film has a peel strength of at least 5N per 10mm width of the unitary film.
• the first and second criteria each comprise methods of identifying and determining physical properties of the material of the uniform film. Also, it will be appreciated that these methods do not necessarily limit the claimed unitary film. Rather, they merely provide a way to determine whether the unitary film has one or more of the characteristic physical properties according to the present disclosure.
• the first criterion refers to Standard Test Method ASTM D3418, which is a standard test method for transition temperatures and enthalpies of fusion and crystallisation of polymers by differential scanning calorimetry.
• ASTM D3418 Standard Test Method for transition temperatures and enthalpies of fusion and crystallisation of polymers by differential scanning calorimetry.
• a technical advantage of the unitary film, as characterised by the first criterion, is that it exhibits an advantageous phase transition temperature range, which is useful for preventing instability in the unitary film during use. For example, in situations where the unitary film is thermally bonded to the conductive elements (e.g., in order to form an electrode assembly), or when the unitary film is thermally bonded to a surface of a solar cell (e.g., in order to form a solar cell assembly).
• the first criterion refers to a method of identifying and determining the at least one temperature of an endothermic peak of the polymeric material of the unitary film. This testing method can be used to identify and determine whether a candidate polymeric material exhibits an endothermic phase transition in the required temperature range, such that it would fall within the scope of the present disclosure.
• the second criterion refers to Standard Test Method ASTM D903, which is a standard test method for peel (or stripping) strength of adhesive bonds.
• the peel strength represents the average load per unit width at a bond line between the film and the substrate, which is required to separate the unitary film, progressively, from the substrate at an angle of approximately 180° and at a separation rate of 152 mm/min.
• the peel strength may be expressed as a force per unit width (e.g., Newtons (or kilograms) per millimetre of width of the unitary film).
• the bond line extends parallel to the width of the unitary film, and defines a line of contact between the film and substrate’s surface.
• a technical advantage of the unitary film, as characterised by the second criterion, is that it exhibits an advantageous range of peel strengths, which are associated with improved adhesive properties of the unitary film.
• the testing method of the second criterion can be used to identify and determine whether a candidate polymeric film exhibits a peel strength in the required range (e.g., at least 5N per 10mm width of the unitary film), such that it would fall within the scope of the present disclosure.
• the peel strength represents a standard measure of the adhesive properties of a film, as determined by Standard Test Method ASTM D903. It will be appreciated that the width direction of the unitary film is substantially perpendicular to the direction in which the peelforce is applied to the unitary film during the 180-degree peel test.
• the adhesive properties may also be defined by the peel strength of the unitary film, which is expressed in units of kg per mm width of the unitary film.
• a unitary film satisfying the requirements of the first and/or second criteria provides increased adhesion, when in use, between the plurality of conductive elements and the unitary film and/or between the solar cell and the unitary film.
• the unitary nature of the film means that it exhibits substantially uniform physical and thermal properties, (e.g., in comparison to a multi-layer film which includes separate backing and adhesive layers which may have different properties).
• the unitary film is less prone to delamination. Accordingly, the unitary film is more stable and simpler to handle during the fabrication of the solar cell assembly, which can lead to improvements in the efficiency of the fabrication process.
• the DSC testing method of the first criterion comprises identifying at least two endothermic peaks in a trace (e.g., a heating or cooling trace) produced by differential scanning calorimetry.
• the trace may be generated by a differential scanning calorimeter configured to determine the temperature and heat flow associated with a thermal transition of a material under investigation.
• thermal transitions may be characterised by the absorption or release of energy by the specimen resulting in a corresponding endothermic or exothermic peak or baseline shift in the trace.
• the areas under the crystallisation exotherm, or fusion endotherm, of the test materials may be compared against the corresponding areas of traces obtained by testing a well characterised standard.
• the material e.g. a sample of the polymeric material
• the calorimeter monitors the heat flow between the two cells as they are heated up.
• the heat flow between the cells is normally constant when the material isn’t undergoing a phase transition.
• the material may, at a certain temperature, undergo a transition (e.g. an endothermic transition) which requires heat to be transferred from the reference cell to the test cell.
• the calorimeter may be configured to output a trace corresponding to the flow of heat being directed either towards, or away from, the test cell (i.e. a test trace).
• a separate trace is typically also produced corresponding to the reference cell (i.e. a reference trace), which is typically a flat line.
• the difference between the test trace and the reference trace is representative of the change in heat flow to the test cell with changing temperature. Such changes may correspond to a transition in the material under investigation.
• the calorimetric data can be evaluated to determine characteristic properties of the material under investigation.
• the data may be presented as traces on a graph of heat flow (W/g) plotted against temperature (°C) and/or time (s).
• the heat flow values represent the power per unit mass that is directed between the cells of the calorimeter.
• the temperature values correspond to the measured temperature of the cell.
• the time values are representative of the rate at which the temperature of the cells increase during the investigation.
• the peak may appear on the resulting graphs as a region of the test trace that deviates from the substantially linear reference trace. In the case of an endothermic transition, the resulting peak may appear in the test trace as a negative peak, or trough.
• the temperature of the endothermic peak may define a peak temperature (Tp) of the endothermic peak (e.g., first or second peak temperatures, respectively).
• Tp peak temperature
• the peak temperature may represent the characteristic temperature of the endothermic transition (e.g. endothermic melting).
• the first endothermic peak in at least one, or each, of the first and second heating traces may be between 40°C and 130°C.
• the first endothermic peak in the second heating trace may be between 80°C and 130°C.
• the differential scanning calorimetry method of the first criterion may comprise identifying a third endothermic peak in at least one, or each, of the first and second heating traces.
• the method may further comprise determining that the third endothermic peak (e.g., in at least one, or each, of the first and second heating traces) is at a temperature between 130°C and 200°C.
• the third endothermic peak in at least one, or each, of the first and second heating traces may be between 130°C and 160°C.
• the first and/or second heating traces may comprise up to three endothermic peaks (e.g., the first, second and third peaks) within the defined temperature range (e.g., between 80°C and 160°C).
• the unitary film may have a third endothermic peak in a temperature range between 130°C and 200°C in the first and second heating traces.
• the differential scanning calorimetry method of the first criterion may comprise measuring the cooling of the polymer material during the first thermal cycle (e.g., a cooling stage of the first thermal cycle) according to Standard Test Method ASTM D3418 to produce a cooling trace.
• the cooling trace may consist of a heat flow (W/g) plotted against temperature (°C) and/or time (s). However, in this case the trace is recorded when the sample material is being cooled.
• the unitary film may comprise an exothermic peak (e.g., an exothermic crystallisation peak) at a temperature in the range between 0°C and 200°C.
• the exothermic peak may be measured by the differential scanning calorimetry method (e.g., according to Standard Test Method ASTM D3418).
• the by the differential scanning calorimetry method may further comprises measuring the cooling of the polymer material during the first thermal cycle to produce a cooling trace; and identifying and determining an exothermic peak at a temperature between 0°C and 200°C.
• the exothermic peak may be between 40°C and 130°C.
• the thermal cycle (e.g., the first and/or second thermal cycles) may comprise a heating stage in which the test and reference materials are heated over time.
• the calorimeter may be controlled to continuously monitor (e.g., with a temperature sensor) the differences in thermal input between a reference material and a test material, to produce a heating trace.
• the heating stage of the first thermal cycle may produce a first heating trace and the heating stage of the second thermal cycle may produce a second heating trace.
• the thermal cycle may also comprise a cooling stage, which may follow the heating stage, and during which the test and reference materials may be allowed to cool over time.
• the temperatures of the reference and test materials may be continuously monitored to produce a cooling trace.
• the cooling stage of the first thermal cycle may follow the heating stage of the first thermal cycle, and may produce a cooling trace.
• the cooling trace shows the release of thermal energy from the test material, which was absorbed during the heating stage.
• the differential scanning calorimetry method may be carried out in an inert atmosphere (e.g., under a purge, or flow, of inert gas).
• the testing environment e.g., including the testing and/or reference samples
• the inert gas may be nitrogen.
• the testing method of the second criterion comprises peeling the unitary film from the substrate according to Standard Test Method ASTM D903 to provide a peel-force trace.
• the method may also comprise determining from the peel-force trace that the unitary film has a peel strength of at least 5N per 10 mm width of the film.
• peel test may be used to determine (e.g., measure) the adhesion between the unitary film and the substrate which are thermally bonded together.
• a peel test apparatus may be used to perform the peel test.
• the peel test apparatus may comprise a motorised tensiometer configured to apply a tensile force between the unitary film and the substrate.
• the apparats may include a tensile force measuring sensor (e.g., a loadcell) to determine the tensile load that is applied during testing.
• the peel test apparatus may include a set of grips, or grippers, which are configured to hold the unitary film and the substrate.
• the peel test apparatus may comprise a controller which is configured to operate the motorised tensiometer to carry out the testing method. In particular, the controller may be capable of controlling the force that is applied to the grippers by the tensiometer, which thereby determines the force (e.g., the ‘peel force’) that is applied to the unitary film.
• the second criterion may also be characterised by thermally bonding the unitary film to a substrate.
• This method step may comprise heating the unitary film to at least 40°C.
• the peel test may comprise allowing the unitary film to cool (e.g., to room temperature (e.g., around 20°C)) for a pre-determined period (e.g., at least 30 minutes) before carrying out the peel-force analysis of the unitary film (e.g., before peeling the film from the substrate).
• the peel test method of the second criterion may comprise arranging the unitary film so that it lies substantially flat on a receiving surface of the substrate. This may be done before the film is thermally bonded (e.g., laminated) to the substrate. Only a portion of the unitary film may be thermally bonded to the substrate. Accordingly, the film may be configured with a free end (e.g., a non-bonded end) which can be readily coupled to a gripper of the peel-test apparatus.
• the unitary film may be arranged in a longitudinal strip.
• a plurality of longitudinal strips may be arranged (e.g., in parallel to each other) on the surface of the substrate.
• the longitudinal strip may comprise a width of around 10 mm.
• the length of the longitudinal strip may comprise a length of at least 100 mm.
• the longitudinal strip may be arranged on the substrate such that the width of the strip is substantially perpendicular to the direction in which the peel-force is applied.
• the peel test may be applied over a distance (e.g., strain) of around 100 mm.
• the unitary film may be peeled from the substrate at a peeling speed of around 100 mm/min.
• the peel-force is continuously monitored. For example, the peel-force may be measured at 10 pm intervals until the maximum peeling distance is reached (e.g., 100 mm).
• the peel strength may be determined by taking an average of the data recorded in the peelforce trace.
• the average peel-force may be determined by averaging the data that is recorded after a minimum peeling distance, or strain, (e.g., 20 mm).
• the data taken before the peeling distance may be discounted, to prevent distortions of the measurement caused by noise in the data which is present at the beginning of each test run.
• the unitary film may be formed of a polymeric material having at least one of the following characteristics: high ductility, low electrical conductivity, high optical transparency, thermal stability, and resistance to shrinkage.
• the unitary film may be configured to transmit at least 70% of incident light having a wavelength of between 280 nm and 1100 nm. Alternatively, the film may be configured to transmit at least 85% of incident light having a wavelength of between 280 nm and 1100 nm.
• the unitary film may have a thickness of at least 25 pm. The thickness of the unitary film may be between 55 pm and 180 pm.
• an electrode assembly which comprises a solar cell, and an electrode assembly of any one of the preceding statements.
• the plurality of electrically conductive elements are arranged on a surface (e.g., a conductive element receiving surface) of the unitary film, such that the electrode assembly can be arranged on a surface of the solar cell, so that the plurality of conductive elements are interposed between the unitary film and the solar cell’s surface.
• the electrode assembly is advantageously configured to form a robust and conductive electrical connection with the surface of the solar cell.
• the solar cell assembly may comprise a first solar cell and a second solar cell.
• the at least one or each of the solar cells may comprise a layered structure which includes a photovoltaic element that can absorb light and generate charge carriers, as would be understood by the skilled person.
• the electrode assembly may be configured to form an electrical connection with a conductive surface (or a conductive portion of a surface) of the solar cell, to extract photogenerated charge carriers from the solar cell.
• At least one, or each, of the solar cells may comprise a front surface and a back surface.
• the front surface may define the surface of the solar cell upon which light is incident when the solar cell assembly is in use (e.g. the frontmost surface of the solar cell).
• the back surface may define the surface of the solar cell which is opposite the front surface (e.g. the backmost surface of the solar cell).
• the back surface of the solar cell may not be directly exposed to incident light during use.
• the solar cell assembly may be configured so that light transmitted (e.g., not absorbed) from front to back through the solar cell is then reflected back towards the solar cell’s back surface, which provides a further opportunity for the light to absorbed.
• At least one, or each, of the electrically conductive elements may comprise a width, an axial length, and a depth.
• Each of the conductive elements may be configured such that its axial length is substantially greater than its width and/or depth.
• the width and axial length of the conductive elements may be measured in perpendicular directions aligned with a plane of the surface of the solar cell upon which the conductive elements are arranged (e.g. the front or back surface of the solar cell).
• the depth may be measured in a direction which is perpendicular to the same plane of the solar cell.
• the solar cell assembly may comprise a first solar cell and a second solar cell, wherein the plurality of electrically conductive elements are configured to electrically couple a front surface of the first solar cell with a back surface of the second solar cell.
• the electrode assembly may be connected (e.g. laminated) onto the respective front and back surfaces of the first and second solar cells.
• At least one of the first and second solar cells may be inverted such that their front surfaces are arranged to face in a substantially downward direction (e.g. substantially vertically down) and their back surfaces are arranged to face in a substantially upward direction (e.g. substantially vertically up).
• a first portion of the electrode assembly which contacts the front surface of the first solar cell may define a front connecting portion, or front connector, of the electrode assembly.
• a second portion of the electrode assembly, which contacts the back surface of the second solar cell may define a back-connecting portion, or back connector of the electrode assembly.
• a first portion of each of the plurality of electrically conductive elements may define the front connector of the electrode assembly.
• a second portion of each of the plurality of conductive elements may define the back connector of the electrode assembly. Accordingly, at least one, or each, of the plurality of conductive elements may extend from the front connector to the back connector of the electrode assembly.
• the electrically conductive element(s) may be configured to bend along an axial direction of the conductive element(s) so as to allow the electrode assembly to be coupled between the respective front and back surfaces of the first and second solar cells (i.e. to allow the conductive element(s) to provide an electrical connection between the front and back connectors).
• the first surface of the conductive element(s) of the back connector may be arranged to define a back surface (i.e. a backmost surface) of the electrode assembly.
• the second surface of the electrically conductive element(s) of the front connector may be arranged to define a front surface (i.e. a frontmost surface) of the electrode assembly.
• the electrically conductive elements of the front and back connectors may define, respectively, a first and second portion of the plurality of conductive elements.
• the first portion of the plurality of conductive elements may be arranged in or on a first unitary film (e.g. an insulating and/or optically transparent film).
• the second portion of the plurality of conductive elements may be arranged in or on a second unitary film (e.g. an insulating and/or optically transparent unitary film).
• the first surface may be exposed from the first unitary film to form an electrical contact with the front surface of the first solar cell
• the second surface may be exposed from the second unitary film to form an electrical contact with the back surface of the second solar cell.
• a third portion of the plurality of conductive elements may be arranged between the first and second portions of the plurality of conductive elements.
• the third portion may be configured to be arranged between the first and second solar cells when the electrode assembly is connected therebetween.
• the third portion may be configured such that the conductive elements in this portion are not arranged in a unitary film (i.e. in contrast to the first and second portions).
• At least one, or each, of the conductive elements may be disposed on a surface of the respective first and second unitary films.
• at least one of the conductive elements may be arranged at least partially within the unitary film.
• the at least one conductive element may be embedded within the unitary film such that a surface of the conductive element protrudes from the surface of the unitary film.
• the first unitary film of the front connector may define a front unitary film of the electrode assembly.
• the second unitary film of the back connector may define a back unitary film of the electrode assembly.
• the front unitary film may be configured such that at least a portion of the first surface of the front connector’s conductive elements is exposed.
• the back unitary film may be configured such that at least a portion of the second surface of the back connector’s conductive elements is exposed.
• the unitary film of the back connector may have a front surface (i.e. facing towards the solar cell), and a back surface (i.e. facing away from the solar cell) opposite the front surface. At least one conductive element of the second portion of the plurality of conductive elements may be disposed on the front surface of the back unitary film.
• Each of the first and second solar cells may comprise a length, a width, and a depth.
• the length of the solar cell may be less than its width, and the depth may be less than both the width and the length.
• the longitudinal and transverse directions across the front and back surfaces of the solar cell may be parallel with the length and width directions of the solar cell, respectively.
• the plurality of conductive elements may be configured to extend across the length of the solar cell, and to be spaced along its width.
• Each of the conductive elements may be configured to extend lengthwise relative to the surface of the solar cell upon which it is overlaid, in a longitudinal direction.
• the conductive elements may be spaced apart in a transverse direction relative to the solar cell surface to define longitudinal-extending spaces between the conductive elements.
• the conductive elements may be parallel or substantially parallel to one another.
• the conductive elements may be equally or substantially equally spaced in the transverse direction. Accordingly, the plurality of conductive elements may form an array of parallel, transversely spaced (e.g. equally spaced) conductive elements.
• the conductive element(s) may be configured to form an electrical contact with an electrically conductive surface (e.g. an electrically conductive portion of a surface) of the solar cell.
• the conductive surface(s) may comprise one or more finger electrodes that are arranged on (e.g., printed on) the front and back surfaces of the layered structure.
• the one or more finger electrodes may be configured to conduct away charge carriers that are generated by the layered structure.
• Each of the solar cells’ conductive surface(s) may comprise a plurality of finger electrodes which extend across the respective solar cell surfaces, as would be understood by the skilled person.
• the finger electrodes may be formed using a printed material, which enables them to be conveniently deposited onto the surfaces of the solar cells.
• the solar cell may be configured to define any type of solar cell structure.
• the solar cell may define a heterojunction type solar cell.
• the solar cell may define a tandem junction solar cell.
• the surface(s) of the solar cell may be textured to form a textured surface corresponding to an uneven surface or having uneven characteristics, as would be understood by the skilled person.
• the textured surface may define an anti-reflection layer, or coating, arranged at the front and/or back surfaces of the solar cell.
• the solar cell may comprise a transparent conductive oxide coating arranged at the front and/or back surfaces of the solar cell.
• the transparent conductive oxide coating may be configured to increase lateral carrier transport to the finger electrodes arranged on the respective surfaces of the solar cell.
• the conductive elements may at least in part form the electrode assembly which is applied to the first and second solar cells to define the solar cell assembly.
• one or more solar cell assemblies according to the present invention may be electrically coupled together and arranged in a housing to define a solar module.
• a second electrode assembly may be provided to couple the front surface of the second solar cell to the back surface of a third solar cell.
• the conductive elements in the second electrode assembly may be as described above for the first electrode assembly.
• the second and third solar cells may be combined with the second electrode assembly to define a second solar cell assembly.
• the conductive elements of the back connector of the first electrode assembly may be aligned with the conductive elements of the front connector of the second electrode assembly, with the second solar cell interposed therebetween.
• the solar module may comprise a frame in which to house the plurality of solar cell assemblies.
• the frame may comprise a front plate and a back plate which are arranged, respectively, on the front and back sides of the plurality of solar cell assemblies.
• At least one or each of the front and back plates may be formed of glass (e.g. a glass sheet).
• the solar module may comprise an encapsulant which may be configured to provide adhesion between the front and back plates and the plurality of solar cell assemblies. In this way, the encapsulant may be arranged between the glass sheet of the solar module, and an insulating optically transparent unitary film of one of the pluralities of solar cell assemblies.
• the encapsulant may be arranged between the back sheet of the solar module, and an insulating optically transparent unitary film of one of the pluralities of solar cell assemblies.
• the encapsulant may be configured to prevent the ingress of moisture into the solar module.
• the encapsulant may be formed of ethylene vinyl acetate (EVA), or any other suitably moisture resistant material.
• a method of manufacturing a solar cell assembly comprises interposing the plurality of electrically conductive elements between the unitary film and a surface of the solar cell.
• the method further comprises thermally bonding the unitary film to the plurality of electrically conductive elements and/or the surface of the solar cell.
• the unitary film may be further configured to attach the conductive elements to the solar cell surface (e.g., to provide a mechanical connection between the conductive elements and the solar cell).
• the unitary film may be configured to maintain the lateral spacing the conductive elements, such that the conductive elements are correctly aligned on the solar cell surface.
• the unitary film may not cover all the respective front and/or back surface(s) of the solar cell on to which it is overlaid.
• the unitary film may be configured to provide structural support for the electrically conductive elements when the conductive elements are being handled, for example, prior to being arranged onto the solar cell.
• the unitary film may be configured such that at least a portion of at least one of the conductive elements is exposed from the film to form an electrical contact with the respective surface of the solar cell.
• the unitary film When the electrode assembly is installed on the solar cell surface, the unitary film may deform to conform to the shape of the conductive elements sandwiched between the unitary film and the solar cell.
• the surface of the unitary film may form ridges/protuberances over the conductive elements and may be substantially planar in regions with no conductive elements.
• the unitary film may comprise a conductive element contacting region which has a non-planar profile.
• the solar cell assembly may comprise a first solar cell and a second solar cell.
• the electrode assembly may be configured to electrically connect the first solar cell to the second solar cell.
• the at least one electrically conductive element may be configured to electrically couple a front surface of the first solar cell with a back surface of the second solar cell.
• the solar cells may each comprise a back (e.g. backmost) surface and a front (e.g. frontmost) surface being opposite the back surface. Accordingly, the method may comprise arranging a portion of the electrode assembly onto the back surface of the second solar cell to define a back connector. The method may further comprise arranging another portion of the electrode assembly onto the front surface of the first solar cell to define a front connector.
• the conductive elements may be coated in a solderable material which has a melting point which is lower than the materials from which the conductive elements are formed.
• the method may comprise applying heat and/or pressure to (e.g. soldering) the first portion of the electrically conductive elements (i.e. of the front connector) to form an electrical contact with the conductive surface of the first solar cell (e.g. the finger electrode), upon which the conductive element is overlaid.
• the method may comprise applying heat and/or pressure (e.g. soldering) the second portion of the conductive elements (i.e. of the back connector) to form an electrical contact with the conductive surface of the second solar cell (e.g. the finger electrode), upon which the conductive element is overlaid.
• the method may comprise first attaching one of the front and back connectors to the respective first and second solar cells, then attaching the other of the front and back connectors to the other of the respective first and second solar cells.
• Fig. 1 is a close-up sectional side view of a solar module including a solar cell assembly, the solar cell assembly comprising a first solar cell coupled to a second solar cell by an electrode assembly;
• Figs. 2A and 2C are plan views of the top (front) and bottom (back) of the first and second solar cells, respectively, as shown in Fig. 1 , respectively;
• Figs. 2B and 2D are transverse sectional views taken through the first and second solar cells, respectively, as shown in Figs. 2A and 2C;
• Figs. 3 to 8 are side views of a solar cell assembly, showing the different stages of a method of manufacturing the solar cell assembly;
• Fig. 9 is a flowchart illustrating a method of manufacturing the solar cell assembly, as shown in Figs. 3 to 8;
• Fig. 10 is a schematic of a differential scanning calorimeter for determining thermal transitions in a material
• Figs. 18 and 19 are schematics of a 180-degree peel tester for determining the peel strength of a polymeric unitary film
• Fig. 20 is a flowchart illustrating a method of determining the peel strength of a unitary film for an electrode assembly of a solar cell; and Figs 21 and 22 are peel-force traces of different polymeric materials determined using the 180-degree peel tester as shown in Figs. 18 and 19, and according to the method as shown in Fig. 20.
• Fig. 1 shows the solar cell assembly 10 arranged within a support assembly 102 of a solar module 100 (e.g. a solar panel).
• the solar cell assembly 10 includes a first solar cell 20, a second solar cell 30 and an electrode assembly 12 which is arranged to electrically couple a front surface 22 of the first solar cell 20 to a back surface 34 of the second solar cell 30.
• a first portion of the electrode assembly 12 is arranged to contact the front surface 22 of the first solar cell 20 to define a front connecting portion, or front connector 12a, of the electrode assembly 12.
• a second portion of the electrode assembly 12 contacts the back surface 34 of the second solar cell 30 to define a back connecting portion, or back connector 12b, of the electrode assembly 12.
• the first and second connectors 12a, 12b are electrically coupled together by a third interconnecting portion 12c which bends between the respective front and back surfaces 22, 34 of the adjacently positioned solar cells 20, 30 of the solar cell assembly 10.
• the solar cell assembly 10 is one of a plurality of solar cell assemblies which are arranged within the support assembly 102.
• a front surface 32 of the second solar cell 30 is electrically coupled to the back surface of a third solar cell (not shown) by a second electrode assembly 14.
• a third electrode assembly 16 is provided to couple a back surface 24 of the first solar cell 20 to the front surface of a fourth solar cell (not shown).
• the second and third solar cells in this arrangement are electrically coupled together by the second electrode assembly 14 to define a second solar cell assembly.
• the plurality of solar cells 20, 30 are thereby coupled together by the electrode assemblies 12, 14, 16 to define a single string.
• a back plate 108 of the support assembly 102 is arranged to enclose the solar cell assembly 10 within the central chamber 106.
• the back plate 108 comprises a reflective sheet which is configured to reflect any light which is incident upon its upper surface, back towards the solar cell assembly 10.
• the central chamber 106 is filled with an encapsulating material (the shaded area shown in Fig. 1) which prevents ingress of external liquid or gaseous entrants.
• Figs. 2A and 2C illustrate the top (front) and bottom (back) view of the first and second solar cells 20, 30, respectively, of the solar cell assembly 10.
• Figs. 2B and 2D show transverse sectional views of the first and second solar cells 20, 30, respectively, taken along the dashed lines A-A and B-B, as shown in Figs. 2A and 2C.
• Each of the solar cells 20, 30 has a length which is the vertical dimension of Figs. 2A and 2C, and a width which is the horizontal dimension of Figs. 2A and 2C.
• the first and second solar cells 20, 30 are arranged in a common transverse plane (as shown in Fig. 1) such that their widthwise and lengthwise dimensions lie in parallel with each other.
• Each of the front surfaces 22, 32 of the respective solar cells define a surface on which light is incident when the solar cell assembly 10 is in use.
• the back surfaces 24, 34 each define a surface which is opposite to the respective front surface 22, 32, as shown in Figs. 2B, 2D.
• Each solar cell 20, 30 includes a layered structure (not shown) arranged between its respective front and back surfaces.
• the layered structure is a multi-layer semiconductor assembly which includes a photovoltaic element (or layer) which is configured to generate electrical charge carriers from the absorption of incident radiation.
• the front and back finger electrodes 26, 36, 28, 38 are each configured to conduct away the electrical charge carriers generated by the respective solar cell 20, 30.
• the first solar cell 20 includes a first plurality of finger electrodes 26 arranged on its front surface 22 (i.e. front finger electrodes), and a second plurality of finger electrodes 28 arranged on its back surface 24 (i.e. back finger electrodes). Similar, the second solar cell 30 includes a first plurality of finger electrodes 36 arranged on its front surface 32, and a second plurality of finger electrodes 38 arranged on its back surface 34.
• a first portion 18a of the plurality of conductive elements 18 defines the front connector 12a of the electrode assembly 12.
• a second portion 18b of the plurality of conductive elements 18 defines the back connector 12b of the electrode assembly 12. Accordingly, each of the plurality of conductive elements 18 extends from the front connector 12a to the back connector 12b of the electrode assembly 12.
• a third portion 18c of the plurality of conductive elements 18 is configured to electrically couple together the respective first and second portions 12a, 12b.
• Each of the conductive elements 18 defines a current collector of the electrode assembly 12. Furthermore, the conductive elements 18 are configured to collect charge carriers from the front finger electrodes 26 of the first solar cell 20 and transport them to the back-finger electrodes 38 of the second solar cell 30, or vice versa. Each of the conductive elements 18 comprises a width, length, and depth. The length of each conductive elements 18 defines an axial length which is substantially greater than its width and depth.
• each of the pluralities of front and back finger electrodes 26, 28, 36, 38 comprises twelve electrodes.
• the finger electrodes 26, 28, 36, 38 are formed of an electrically conductive material, which is formed of a metallic alloy comprising Ag. It will be understood that the electrically conductive material is a printed material, which enables the finger electrodes to be conveniently deposited onto the respective surfaces of the solar cells.
• the first and second portions 18a, 18b of the plurality of conductive elements 18 are parallel and extend lengthwise relative to the front and back surfaces 22, 34 of the solar cells, in a longitudinal direction (the vertical direction in Fig. 2A).
• the conductive elements 18 are also equally spaced apart in a transverse direction relative to the front and back surfaces 22, 34 (the horizontal direction in Fig. 2A) to define longitudinal-extending spaces between the conductive elements 18. Accordingly, each one of the first and second portions 18a, 18b defines an array of parallel, transversely spaced conductive elements 18.
• Each of the first portions 18a of the plurality of conductive elements 18 are axially aligned with the corresponding second portions 18b of the conductive elements 18 of the same electrode assembly 12. Also, the second portions 18b of conductive elements 18 of the first electrode assembly 12 are axially aligned with the first portions 18a of the conductive elements 18 of the second electrode assembly 14, with the second solar cell 30 interposed between. Accordingly, the pluralities of front and back finger electrodes 26, 38 are arranged perpendicular to the first and second portions 18a, 18b of the plurality of conductive elements 18, as shown in Figs. 2A and 2C.
• the number of conductive elements 18 of the electrode assembly 12 is between 4 and 20. According to the embodiment described herein the first electrode assembly 12 has sixteen conductive elements 18, as shown in Figs 2A to 2D. It will be appreciated that, in some other embodiments, a different number of conductive elements and/or finger electrodes may be present, without departing from the scope of the present invention.
• the conductive elements 18 each have a circular transverse cross-sectional shape (i.e. transverse to the axial length of the conductive element 18), as shown in Figs. 2B and 2D.
• the conductive elements 18 may be configured with different cross-sectional shapes, without departing from the scope of the present invention.
• Each of the conductive elements 18 comprises a first surface 50 which is configured to electrically contact the front surface 22 of the first solar cell 20, as shown in Fig. 1.
• Each conductive element 18 also comprises a second surface 52 configured to electrically contact the back surface 34 of the second solar cell 30, as shown in Fig. 1.
• Each of the conductive elements 18 is formed from a single wire portion (i.e. the first and second portions 18a, 18b of each conductive element 18 are integrally formed with each other). In this way, the conductive elements 18 provide a direct electrical connection between the first and second solar cells 20, 30, which increases the flow of current therebetween.
• the plurality of conductive elements 18 are covered in a coating (not shown) which is configured, when in use, to solder the respective first and second surfaces 50, 52 to a respective surface of the solar cells 20, 30 upon which they are overlaid.
• the coating is an electrically conductive material having a melting point which is lower than that of the conductive element 18.
• Figs. 2A and 2B shows the first portion 18a of the conductive elements 18 on the front surface 22 of the first solar cell 20 (i.e. the front connector 12a of the electrode assembly 12), whereas Figs. 2C and 2D show the second portion 18b of the same conductive elements 18 on the back surface 34 of the second solar cell 30 (i.e. the back connector 12b of the electrode assembly 12).
• the electrode assembly 12 comprises an insulating and optically transparent film 40 which is thermally bonded to the conductive elements 18.
• the film has a unitary construction (i.e. it is formed of a single layer of material, not a plurality of discrete layers), and is formed of a polymeric material.
• Certain characteristic properties of the polymeric material which determine how the unitary film 40 adheres to the conductive elements, and/or the solar cell surfaces, can be determined using differential scanning calorimetry (DSC) analysis, as will be described in more detail below.
• DSC differential scanning calorimetry
• the polymeric material may be formed from a polymer resin which comprises at least one of a polyolefin elastomer (POE), polyvinylbutyral (PVB) hydrocarbon ionomer, thermoplastic organo-silicon, silicon rubber, polyurethane, thermoplastic silicone elastomer (TPSE) and ethylene-vinyl acetate (EVA).
• POE polyolefin elastomer
• PVB polyvinylbutyral
• TPSE thermoplastic silicone elastomer
• EVA ethylene-vinyl acetate
• the polymeric material is selected to encompass the following characteristics: high ductility, low electrical conductivity, high optical transparency, thermal stability, and resistance to shrinkage.
• the unitary film is configured with a haze parameter of less than 35%, alternatively up to 25%, optionally up to 18 %.
• the haze parameter of a polymeric material may be defined as a measure of the proportion of incident light which is scattered by more than 2.5°, as measured by a spectrophotometer.
• the unitary film is configured to transmit at least 85% of incident light having a wavelength of between 280 nm and 1100 nm.
• the unitary film has a thickness of at least 25 pm, optionally at least 55 pm and/or up to 180 pm.
• the front and back film portions 42, 44 are thinner than the conductive elements 18.
• the conductive elements 18 have a thickness of between 200 pm and 300 pm.
• the first and second portions 18a, 18b of the plurality of conductive elements 18 are each arranged in separate film portions, which are arranged on the front and back surfaces 22, 34 of the respective solar cells.
• the front connector 12a comprises a first film portion which defines a front film portion 42
• the back connector 12b comprises a second film portion which defines a back-film portion 44.
• the conductive elements 18 in the third portion 18c are free from any film covering.
• the film 42 is arranged to contact the front surface 22 of the solar cell in the areas in-between the conductive elements 18 and the front finger electrodes 26.
• the back-film portion 44 is configured in the same way for the back connector 12b.
• Each of the films 42, 44 is configured to at least partially (e.g. completely) envelope, or surround, the respective conductive elements 18 and the respective finger electrodes 26, 38, as shown in Figs. 2B and 2D.
• the front and back film portions 42, 44 are arranged to provide adhesion between the solar cells and the conductive elements 18 so that the conductive elements are correctly arranged on the solar cells (i.e. aligned with the finger electrodes).
• the front and back film portions 42, 44 may not fully cover the respective surfaces of the solar cells.
• the films may be configured to conform to the structural components of solar cells and/or conductive elements.
• the film 40 may be comprised of elongate channels recessed towards the solar cell in the regions of the back surface 34 in-between conductive elements, and may form ridges/protuberances over the structures electrodes (e.g. finger electrodes and conductive elements) where they are present.
• the method commences with a first method step 202 in which a plurality of conductive elements 18 are thermally bonded to a unitary film 40 to form the electrode assembly 12.
• the unitary film 40 comprises separate first and second film portions 40a, 40b.
• the method comprises arranging the first portion 18a of the plurality of conductive elements 18 onto the first unitary film portion 40a to define the front connector 12a of the electrode assembly 12.
• the method further includes arranging the second unitary film portion 42 onto the second portion 18b of the plurality of conductive elements 18 to define the back portion 12b of the electrode assembly 12.
• Heat and pressure are applied to the unitary film portions 42, 44, as shown in Fig. 4, which causes the film’s polymeric material to soften, and thereby adheres the film portions to the conductive elements 18.
• the unitary film 40 is heated using an infrared lamp (not shown).
• the required heat may be applied by any suitable heating means, such as a convection heating element, a hot air blower or an induction heating element.
• the heating means is configurable to control the temperature of the unitary film 40 during the bonding process, as will be explained in more detail below.
• first and second portions 18a, 18b, of the plurality of conductive elements 18 can be attached to the respective unitary film portions 42, 44 at the same time, or during separate processes.
• the first portion 18a of the plurality of conductive elements defines a front connector 12a of the electrode assembly 12
• the second conductive element portions 18b defines a back connector 12a.
• the first and second unitary film portions 42, 44 define front and back unitary film portions, respectively.
• a first solar cell 20 is thermally bonded to the front connector 12a of the electrode assembly 12.
• the conductive elements’ first portions 18a are brought into contact with the front surface 22 of the first solar cell 20, as shown in Fig. 5.
• the conductive elements of the front connector 12a are overlaid onto the front surface 22 of the first solar cell 22 such that they sit perpendicular to the front finger electrodes, as shown in Fig. 2A.
• the method further involves heating and/or applying pressure to the conductive elements 18 of the front connector 12a to physically bond them to the first solar cell’s front surface 22 under a compressive force, as illustrated in Fig. 6.
• the application of heat and pressure also laminates the front unitary film portion 42 onto the front surface 22 of the first solar cell 20.
• a second solar cell 30 is thermally bonded to the back connector 12b of the electrode 12, as shown in Figs. 7 and 8.
• the method comprises overlaying the back connector 12b onto the back surface 34 of the second solar cell 30 such that they sit perpendicular to the finger electrodes 38, as shown in Fig. 2D.
• the third method step 206 further involves heating and/or applying pressure to the conductive elements 18 in the second connector 12b to bond the electrode assembly 12 the second solar cell’s back surface 34 under a compressive force, as illustrated in Fig. 8.
• the application of heat and pressure also laminates the back unitary film portion 44 onto the back surface 34 of the second solar cell 30.
• a heat resistant sheet e.g., formed of PTFE
• the sheet is configured to prevent adhesion between the substrate 82 and the free end of strip during the subsequent bonding method step.
• the strips are placed in a laminator and heated to at least 50°C. Once the strips are bonded to the surface 82, they are allowed to cool for a pre-determined period (e.g., at least 30 minutes) before carrying out the peel-force analysis (e.g., before peeling the film from the substrate 82).
• a pre-determined period e.g., at least 30 minutes

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• 2021
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• 2022
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