BACKGROUND OF THE INVENTION

1. Field of Invention

This invention relates to photovoltaic (PV) modules and methods for making them.

2. Description of Related Art

The design and production of conventional PV modules comprised of crystalline silicon PV cells has remained virtually unchanged for more than thirty years. A typical PV cell comprises semiconductor material with at least one p-n junction and front and back side surfaces. Current collecting electrodes are connected to the front and back side surfaces to facilitate connection to other PV cells or to external electrical circuits.

When a conventional crystalline PV cell is illuminated, it generates an electric current of about 34 mA/cm ² at about 0.6 - 0.62V. A plurality of PV cells are typically electrically interconnected in series and/or in parallel strings to form a PV module that produces higher voltages and/or currents than a single PV cell.

PV cells may be connected together in strings using metallic tabs, made from tinned copper, for example or they may be connected together by a current collecting electrode of the type described in US patent No. 8,013,239, for example. A typical PV module may comprise 36-100 series interconnected PV cells, for example, and these may be formed by 2 to 4 substrings interconnected in series to achieve higher voltages and/or currents than would be obtainable with a single PV cell or substring.

Since PV modules are generally expected to operate outdoors for typically 25 years without substantial degradation, their construction must withstand various weather and environmental conditions. Typical PV modules may be comprised of a multilayered sandwich comprising a plurality of firmly interconnected layers of different materials facilitating protection against water, salt and aggressive gas penetration, mechanical strength against wind and snow load. These materials also provide for electrical insulation.

To make a typical PV module a front side protective sheet formed of optically transparent low iron tempered glass, for example, is covered with a first sheet of polymeric, thermally activated encapsulant material such as thermoplastic polyolefin (TPO). TPO is a polymer/filler blend usually consisting of some fraction of PP (polypropylene), PE (polyethylene), BCPP (block copolymer polypropylene), rubber, and a reinforcing filler. Alternatively, a sheet of thermoplastic urethane (TPU) or curable ethylene vinyl acetate (EVA) polymer may be used as the encapsulant material instead of a sheet of TPO, for example.

Then, an array of pre-connected PV cells is placed onto the encapsulant material in such a way that the front sides of the cells face toward the transparent protective glass sheet. A back side of the array is covered with a second layer of encapsulant material and then a back side protective sheet of weather protecting material is placed over the second layer of encapsulant material. The back side protective sheet may be made of Tedlar® by DuPont USA, for example or TPO-based PV-FSZ777® material produced by Dai Nippon Printing (DNP) Co. Ltd. of Japan. The thickness of each of the first and second sheets of encapsulant material may be about 500 microns, for example. The glass front protective sheet, encapsulant layers, cells and back side protective sheet are typically vacuum laminated to protect the PV cells from moisture penetration from the front side, back side and edges.

An aluminum frame is placed around the perimeter edges and is secured thereto by silicone and/or double sided adhesive tape to further protect the PV module against damage, wind and snow loads and to assist in mounting of the module to supporting racks. The encapsulant material imparts mechanical strength and sealing properties to the PV module, between the PV cells and the front and rear protective sheets but the material itself is expensive and its use requires a time consuming vacuum lamination process involving uniformly heating all material layers. Therefore, the use of encapsulant material contributes a significant cost expense to the overall process of making a PV module.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, there is provided a first terminal electrode apparatus for use on a photovoltaic cell. The apparatus includes a first electrically insulating optically transparent film having first inner and outer planar surfaces, a first inner adhesive layer on the first inner planar surface, and a first plurality of substantially parallel, electrically conductive wires on the first inner planar surface and embedded into the first inner adhesive layer. The first inner adhesive layer has a thickness less than a thickness of the wires embedded therein such that parts of surfaces of the wires protrude from the first inner adhesive layer. At least parts of the surfaces of the wires are coated with a low-melting point alloy. The apparatus further includes a first busbar on the first inner planar surface, the wires of the first plurality being in electrical contact with the first busbar, a conductor connected to and extending from the first busbar for connecting the first busbar to a circuit, a first, transparent outer adhesive layer on the first outer planar surface of the first film for directly adhesively securing the first film to an inner surface of a first protector, and a first release sheet on the first outer adhesive layer, for preventing the first outer adhesive layer from adhesion when the first inner adhesive layer is being activated.

The first outer adhesive layer may include a first thermoplastic adhesive. The first outer adhesive layer may extend entirely across the first outer planar surface. The first thermoplastic adhesive may have a softening temperature of between about 90 degrees Celsius to about 130 degrees Celsius.

The first thermoplastic adhesive layer may have a thickness of between about 30 microns to about 100 microns.

In accordance with another aspect of the invention, there is provided a first terminal PV cell assembly including the first terminal electrode apparatus above and a PV cell having an electrically conductive front side surface and an electrically conductive back side surface. The electrically conductive front side surface has current collection contacts thereon and the first inner adhesive layer adhesively secures the first film to the front side electrically conductive surface. The low melting point alloy solders the parts of the surfaces of the wires protruding from the first inner adhesive layer into direct ohmic contact with the current collection contacts on the front side electrically conductive surface to facilitate conducting electric current to or from the front side electrically conductive surface.

In accordance with another aspect of the invention, there is provided a second terminal PV cell assembly including the first terminal electrode apparatus above and a PV cell having an electrically conductive front side surface and an electrically conductive back side surface. The first inner adhesive layer adhesively secures the first film to the back side electrically conductive surface of the PV cell and the low melting point alloy on the parts of the surfaces of the wires protruding from the first inner adhesive layer are in direct ohmic contact with the back side electrically conductive surface to facilitate conducting electric current to or from the back side electrically conductive surface. In accordance with another aspect of the invention, there is provided a PV cell assembly including the first terminal PV cell assembly above. The PV cell assembly may further include a second terminal electrode apparatus including a second electrically insulating optically transparent film having second inner and outer planar surfaces, a second inner adhesive layer on the second inner planar surface and a second plurality of substantially parallel, electrically conductive wires on the second inner planar surface and embedded into the second inner adhesive layer. The second inner adhesive layer may have a thickness less than a thickness of the wires embedded therein such that parts of surfaces of the wires protrude from the second inner adhesive layer. At least parts of the surfaces of the wires are coated with a low-melting point alloy. The second terminal electrode further includes a second busbar on the second inner planar surface, the wires of the second plurality being in electrical contact with the second busbar, and a second conductor connected to and extending from the second busbar for connecting the second busbar to the circuit. A second, transparent outer adhesive layer is provided on the second outer planar surface of the second film for directly adhesively securing the second film to an inner surface of a second protector. The apparatus further includes a second release sheet on the second outer adhesive layer, for preventing the second outer adhesive layer from adhesion when the first inner adhesive layer is being activated. The second inner adhesive layer adhesively secures the second film to the front side electrically conductive surface of the PV cell and the low melting point alloy solders the parts of the surfaces of the wires protruding from the second inner adhesive layer into direct ohmic contact with the front side electrically conductive surface to facilitate conducting electric current to or from the front side electrically conductive surface.

The second outer adhesive layer may include a second thermoplastic adhesive.

The second outer adhesive layer may extend entirely across the second outer planar surface.

The second thermoplastic adhesive may have a softening temperature of between about 90 degrees Celsius to about 130 degrees Celsius. The second thermoplastic adhesive layer may have a thickness of between about 30 microns to about 100 microns.

In accordance with another aspect of the invention, there is provided an intermediate electrode apparatus for connecting adjacent PV cells together.

The intermediate electrode apparatus includes a first electrode portion including a first electrically insulating optically transparent film having first inner and outer planar surface, a first inner adhesive layer on the first inner planar surface, and a first plurality of substantially parallel, electrically conductive wires on the first inner planar surface and embedded into the first inner adhesive layer. The first inner adhesive layer and the first plurality of wires face in a first direction, and the first inner adhesive layer has a thickness less than a thickness of the wires embedded therein such that parts of surfaces of the wires protrude from the first inner adhesive layer and at least these parts of the surfaces of the wires are coated with a low-melting point alloy. The apparatus further includes a first busbar on the first inner planar surface. The wires of the first plurality are in electrical contact with the first busbar. A first outer adhesive layer is provided on the first outer planar surface of the first film for directly adhesively securing the first film to an inner surface of a rear protective sheet. A first release sheet is provided on the first outer adhesive layer, for preventing the first outer adhesive layer from adhesion when the first inner adhesive layer is being activated. The intermediate electrode apparatus further includes a second electrode portion adjacent the first electrode portion. The second electrode portion includes a second electrically insulating optically transparent film having second inner and outer planar surfaces, a second inner adhesive layer on the second inner planar surface, and a second plurality of substantially parallel, electrically conductive wires on the second inner planar surface and embedded into the second inner adhesive layer. The second inner adhesive layer and the second plurality of wires face in a direction opposite to the first direction, and the second inner adhesive layer has a thickness less than a thickness of the wires embedded therein such that parts of surfaces of the wires protrude from the second inner adhesive layer. At least parts of the surfaces of the wires are coated with a low-melting point alloy. The wires of the second plurality are in electrical contact with the first busbar to electrically connect the first and second pluralities of wires together. A second transparent outer adhesive layer is provided on the second outer planar surface of the second film for directly adhesively securing the second film to an inner surface of a front protective sheet, and a second release sheet is provided on the second outer adhesive layer, for preventing the second outer adhesive layer from adhesion when the second inner adhesive layer is being activated. The first outer adhesive layer may include a first thermoplastic adhesive and the second outer adhesive layer may include a second thermoplastic adhesive.

The first and second outer adhesive layers may extend entirely across the first and second outer planar surfaces respectively.

The first and second thermoplastic adhesives may have a softening temperature of between about 90 degrees Celsius to about 130 degrees Celsius.

The first and second thermoplastic adhesive layers may each have a thickness of between about 30 microns to about 100 microns.

In accordance with another aspect of the invention, there is provided an intermediate PV cell assembly including the intermediate electrode apparatus described above and further including a PV cell having an electrically conductive front side surface and an electrically conductive back side surface. The first inner adhesive layer adhesively secures the first film to the back side electrically conductive surface of the PV cell and the low melting point alloy on the parts of the surfaces of the wires protruding from the first inner adhesive layer is in direct ohmic contact with the back side electrically conductive surface to facilitate conducting electric current to or from the back side electrically conductive surface. In accordance with another aspect of the invention, there is provided an intermediate PV cell assembly including the intermediate electrode apparatus described above and further including a PV cell having an electrically conductive front side surface and an electrically conductive back side surface.

The electrically conductive front side surface may have current collection contacts thereon for collecting current from the PV cell and the second inner adhesive layer adhesively secures the second film to the front side electrically conductive surface of the PV cell. The low melting point alloy solders the parts of the surfaces of the wires protruding from the second inner adhesive layer into direct ohmic contact with the current collection contacts on the front side electrically conductive surface to facilitate conducting electric current to or from the front side electrically conductive surface. In accordance with another aspect of the invention, there is provided a PV string including the first terminal electrode described above and a first intermediate PV cell assembly. The first inner adhesive layer of the first terminal electrode is bonded to the back side surface of the PV cell of the first intermediate PV cell assembly and the low melting point alloy on the protruding portions of the wires embedded in the first inner adhesive layer of the first terminal electrode are in direct ohmic contact with the back side surface of the PV cell of the first intermediate PV cell assembly. The string further includes a first terminal PV cell assembly as described above. The first inner adhesive layer of the first electrode portion of the first intermediate electrode assembly is bonded to a back side electrically conductive surface of a PV cell of the terminal PV cell assembly and the low melting point alloy on the protruding portions of the wires embedded in the first inner adhesive layer of the first intermediate electrode are in direct ohmic contact with the back side surface of the PV cell of the terminal PV cell assembly.

In accordance with another aspect of the invention, there is provided a PV string including the first terminal electrode described above and a first intermediate PV cell assembly. The first inner adhesive layer of the terminal electrode is bonded to a front side surface of a PV cell of the first intermediate PV cell assembly and the wires embedded in the first inner adhesive layer of the terminal electrode are soldered to the front side surface of the PV cell of the first intermediate PV cell assembly by the low melting point alloy on the protruding portions of the wires embedded in the first inner adhesive layer of the first terminal electrode. The PV string further includes a second terminal PV cell assembly as described above. A second inner adhesive layer of the second electrode portion of the first intermediate electrode assembly is bonded to the front side electrically conductive surface of the PV cell of the second terminal PV cell assembly and the wires embedded in the second inner adhesive layer of the first intermediate electrode are soldered to the front side surface of the PV cell of the terminal PV cell assembly by the low melting point alloy on the protruding portions of the wires embedded in the second inner adhesive layer of the first intermediate PV cell assembly.

In accordance with another aspect of the invention, there is provided a PV string including the terminal electrode described above and a plurality of intermediate PV cell assemblies connected in series order. The first inner adhesive layer of the terminal electrode is bonded to a back side surface of a PV cell of a first one of the intermediate PV cell assemblies and the low melting point alloy on the protruding portions of the wires embedded in the first inner adhesive layer of the first terminal electrode are in direct ohmic contact with the back side surface of the PV cell of the first intermediate PV cell assembly. The PV string further includes a terminal PV cell assembly. The first inner adhesive layer of the first electrode portion of a final intermediate electrode assembly of the plurality of intermediate electrode assemblies is bonded to a back side electrically conductive surface of a PV cell of the terminal PV cell assembly and the low melting point alloy on the protruding portions of the wires embedded in the first inner adhesive layer of the final intermediate electrode assembly are in direct ohmic contact with the back side surface of the PV cell of the terminal PV cell assembly. Starting with the first intermediate PV cell assembly, the back side surfaces of PV cells of subsequent intermediate PV cell assemblies are bonded by respective first inner adhesive layers to the first inner planar surfaces on immediately prior PV cell assemblies and the low melting point alloy on respective pluralities of wires embedded in the respective first inner adhesive layers is in direct ohmic contact with the back side surfaces of respective subsequent intermediate PV cell assemblies, to connect the plurality of intermediate PV cell assemblies together, between the terminal electrode and the terminal PV cell assembly.

In accordance with another aspect of the invention, there is provided a PV string including the terminal electrode described above and a plurality of intermediate PV cell assemblies. The first inner adhesive layer of the terminal electrode is bonded to the front side surface of a PV cell of a first one of the intermediate PV cell assemblies and the wires embedded in the first inner adhesive layer of the terminal electrode are soldered to the front side surface of the PV cell of a first one of the intermediate PV cell assemblies by the low melting point alloy on the protruding portions of the wires embedded in the first inner adhesive layer of the first terminal electrode. The PV string further includes a terminal PV cell assembly. A second inner adhesive layer of a second electrode portion of a final intermediate electrode assembly of the plurality of intermediate electrode assemblies is bonded to the front side electrically conductive surface of the PV cell of the terminal PV cell assembly and the wires embedded in the second inner adhesive layer of the terminal electrode are soldered to the front side surface of the PV cell of the terminal PV cell assembly by the low melting point alloy on the protruding portions of the wires embedded in the second inner adhesive layer of the final intermediate PV cell assembly. Starting with the first intermediate PV cell assembly, the front side surfaces of PV cells of subsequent intermediate PV cell assemblies are bonded by respective second inner adhesive layers on immediately prior PV cell assemblies and respective pluralities of wires embedded in the respective second inner adhesive layers are soldered to the front side surfaces of the subsequent intermediate PV cell assemblies by the low melting point alloy on the protruding surfaces of the wires to connect the plurality of intermediate PV cell assemblies together, between the terminal electrode and the terminal PV cell assembly. ln accordance with another aspect of the invention, there is provided a PV panel including any of the PV strings described above and front and rear protective sheets. The front protective sheet may be transparent to admit light therethrough, and each of the front and rear protective sheets has an inside surface and an outside surface. The PV string is sandwiched between the front and rear protective sheets and the outer adhesive layers of the electrodes comprising the PV string are adhesively bonded to at least one of the inside surfaces.

In accordance with another aspect of the invention, there is provided a method of making a PV panel. The method may involve placing a PV cell assembly as described above between front and rear protective sheets. At least the front protective sheet may be transparent to admit light therethrough and each of the front and rear protective sheets may have an inside surface and an outside surface. Placing may involve causing the PV cell assembly to be sandwiched between the inside surfaces of the front and rear protective sheets, and causing the first outer adhesive layer on the first terminal electrode to directly adhesively secure the first outer planar surface of the first terminal electrode to the inside surface of the rear protective sheet, and causing the second outer adhesive layer on the second terminal electrode to directly adhesively secure the second outer planar surface of the second terminal electrode to the inside surface of the front protective sheet. The method may further involve peeling off the fist and second release sheets that prevent the first and second outer adhesive layers from adhesion, prior to causing the first and second outer adhesive layers to be placed into contact with the inner surfaces of the rear and front protective sheets respectively. The method may further involve causing the first and second conductors to be accessible outside of the front and rear protective sheets to permit connecting the PV module to an electrical circuit. The method may further involve activating the first and second outer adhesive layers to cause them to adhere to the inner surfaces of the rear and front protective sheets respectively. Activating may involve exposing a volume defined between the rear and front protective sheets to a vacuum to draw air from between the rear and front protective sheets, pressing the rear and front protective sheets together and heating the first and second outer adhesive layers sufficiently to cause them to bond to the inner surfaces of the rear and front protective sheets respectively.

In accordance with another aspect of the invention, there is provided a method of making a PV panel. The method may involve placing at least one PV cell string as described above between front and rear protective sheets. At least the front protective sheet may be transparent to admit light therethrough and each of the front and rear protective sheets has an inside surface and an outside surface. Placing may involve causing the at least one PV cell string to be sandwiched between the inside surfaces of the front and rear protective sheets, and causing the first outer adhesive layer on the first terminal electrode to directly adhesively secure the first outer planar surface of the first terminal electrode to the inside surface of the front or rear protective sheet, causing the second outer adhesive layer on the end terminal electrode to directly adhesively secure the second outer planar surface of the end terminal electrode to the inside surface of the front or rear protective sheet, and causing the first and second outer adhesive layers on each of the intermediate electrodes to directly adhesively secure respective first and second outer planar surfaces of respective the intermediate electrodes to the inside surface of the front or rear protective sheet. The method may further involve peeling off release sheets that prevent the outer adhesive layers from adhesion, prior placing to the PV string assembly between the first and second protective sheets. The method may further involve activating the outer adhesive layers to cause them to adhere to the inner surface of the front or rear protective sheet.

The method may further involve exposing a volume defined between the front and rear protective sheets to a vacuum to draw air from between the front and rear protective sheets, pressing the front and rear protective sheets together and heating the outer adhesive layers sufficiently to cause them to bond to the inner surface of the front or rear protective sheet. Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures. BRIEF DESCRIPTION OF THE DRAWINGS

In drawings which illustrate embodiments of the invention,

Figure 1 is an oblique view of a single-cell photovoltaic (PV) module according to a first embodiment of the invention;

Figure 2 is an exploded view of a PV panel assembly of the PV module of

Figure 1 ;

Figure 3 is an oblique view of a front side terminal electrode of the PV panel assembly shown in Figure 2;

Figure 4 is a side view of the front side electrode shown in Figure 3;

Figure 5 is an oblique view of a back side terminal electrode of the PV panel assembly shown in Figure 2;

Figure 6 is a side view of the back side terminal electrode shown in Figure

5;

Figure 7 is a cross-sectional view of a PV cell assembly of the PV panel assembly shown in Figure 2 laminated together;

Figure 8 is an oblique view of the PV panel assembly shown in Figure 2,

with release sheets thereon;

Figure 9 is an oblique view of a 4-cell PV module apparatus according to a second embodiment of the invention; Figure 10 is an exploded oblique view of a PV panel assembly of the apparatus shown in Figure 9;

Figure 11 is an oblique top view of an intermediate electrode of a PV cell string of the PV panel assembly shown in Figure 10;

Figure 12 is an oblique top view of an intermediate PV cell assembly comprising the intermediate electrode of Figure 11 secured to a

PV cell;

Figure 13 is an oblique top view of a PV cell assembly, comprising the terminal electrode of Figures 3 and 4 secured to a PV cell;

Figure 14 is an oblique view illustrating a first step in a process for making a

PV cell string of the PV panel assembly shown in Figure 10;

Figure 15 is an oblique top view of the PV cell assembly of Figure 12 placed on the terminal electrode shown in Figure 14;

Figure 16 is an oblique top view of the PV cell string of the PV panel assembly shown in Figure 10 according to a first embodiment, after completion of the process for making a PV cell string in which electrodes are pre-connected to front side surfaces of cells in the string;

Figure 17 is an oblique view of a PV cell string according to another embodiment in which electrodes are pre-connected to back side surfaces of cells in the string;

Figure 18 is an oblique view of an intermediate PV cell assembly used in the

PV cell string shown in Figure 17; and

Figure 19 is an oblique view of a terminal PV cell assembly used in the PV cell string shown in Figure 17.

DETAILED DESCRIPTION

Referring to Figure 1 , a single Photovoltaic (PV) cell photovoltaic module according to a first embodiment of the invention is shown generally at 20. The PV module 20 includes a PV panel shown generally at 22 having edges, not shown in Figure 1 , that are protected by a surrounding metallic frame 24. Referring to Figure 2, the PV panel 22 is shown in greater detail and comprises front and rear protective sheets 26 and 28 with a PV cell assembly 30therebetween. The front protective sheet 26 is comprised of a thin sheet of transparent material. In one embodiment, the material may be a low iron tempered glass and in another embodiment, the material may be a film material such as a transparent type of Tedlar® made by DuPont USA for example. The front protective sheet may have a thickness of approximately about 600um to about 0.5 cm, for example. The rear protective sheet 28 may be formed of the same material as the front protective sheet 26, or could be lcosolar ® 4002 available from Isovoltaic AG of Austria or a film material such as PV-FS Z777 made by Dai Nippon Printing Co. Ltd. Packaging Division of DNP Techno Film Co. Ltd. Of Japan, for example. These materials are not transparent and therefore not suitable for the front protective sheet, but could be used for the rear protective sheet. The front protective sheet 26 must be transparent to permit light to pass therethrough. The rear protective sheet 28 need not be transparent but can be transparent, if desired.

Each of the front and rear protective sheets 26 and 28 has an inside surface and an outside surface, the inside surface of the front protective sheet being shown at 32 and the outside surface being shown at 34. The inside surface of the rear protective sheet 28 is shown at 36 and the outside surface of the rear protective sheet is shown at 38.

The PV cell assembly 30 further includes a first photovoltaic cell 40 having a front side electrically conductive surface 42 and a back side electrically conductive surface 44. The front side surface 42 typically has a plurality of parallel spaced apart conductive contacts referred to as "fingers" 45, for example, formed therein to collect electric current from the front side conductive surface of the first PV cell 40.

The back side conductive surface 44 is typically provided by a back surface field (BSF) layer formed of a fired aluminum paste, for example which typically completely covers the back side surface of the PV cell, making the entire back side surface suitably electrically conductive.

The PV cell assembly 30 further includes a front side terminal electrode 46 for connecting the front side surface 42 of the first PV cell 40 to an electrical circuit and includes a back side terminal electrode 48 for connecting the back side surface 44 to the electrical circuit. The front and back side terminal electrodes 46 and 48 are generally as described in United States Patent No. 7,432,438 and United States Patent No. 8,013,239 with some modifications which will be understood from the description below.

Referring to Figures 3 and 4, the front side terminal electrode 46 is shown in greater detail. The front side terminal electrode 46 includes a first electrically insulating optically transparent film 50. A wide range of materials may be used as the first electrically insulating optically transparent film 50. In general, the film 50 must have a high ductility, good insulating characteristics, optical transparency, thermal and ultraviolet light stability, resistance to shrinkage and must have a good adhesive carrying ability. Examples of such materials are cellophane®, rayon, acetate, fluororesin, polysulfone, epoxy resin, polyamide resin, Mylar®, Tedlar® or modified ETFE fluoropolymer resin such as Tefzel®, and polyethylene terephthalate (PET) also known as polyester®.

The first film 50 should be sufficiently thick, so that it is sufficiently stable to carry an adhesive and to permit pulling under pressure and to withstand heat without shrinkage, to enable heat activation of any adhesive it carries. At the same time, the first film 50 should be as thin as possible in order to achieve high elasticity and transparency to light. Preferably, the thickness of the first film 50 is between about 10 and about 50 μηι. The first film 50 is dimensioned to have a width 51 approximately the same as a width of the PV cell on which it is intended to be secured and is dimensioned to have a length 53 slightly longer than a length 55 of the PV cell to which it is to be secured, so that it has a first extending portion 57. Where the PV cell is about 15.5 cm square, for example, the extending portion may extend between about 0.5cm to about 1.5cm beyond a perimeter edge of the PV cell. The first film 50 also has first inner and outer planar surfaces 52 and 54 respectively. The first inner planar surface 52 is coated with a first inner adhesive layer 56. The first inner adhesive layer 56 may be provided by any of a wide range of materials and desirably has a softening temperature ranging from about 90 to about 130°C and has a good adhesion to the selected first film 50 and to the front side conductive surface (42) of the first

PV cell (40). Preferred materials for use as the first inner adhesive layer 56 include thermally activated ethylene vinyl acetate derivatives or thermoplastic olefin (TPO) produced by Dai Nippon Printing (DNP) Co. Ltd. of Japan or silicon adhesive materials produced by Wacker Chemie AG of Germany, for example.

A first plurality of substantially parallel electrically conductive wires 58 lies on the first inner planar surface 52 and the wires are embedded into the first inner adhesive layer 56. The first inner adhesive layer 56 is formed to have a thickness less than a thickness of the wires embedded therein, such that parts of surfaces of the wires protrude from the first inner adhesive layer 56. The surfaces of the wires are pre-coated with a low melting point alloy coating 59 such as an alloy comprised of 48% tin and 52% indium, for example. Referring back to Figure 2, the first inner adhesive layer 56 is used to adhesively secure the first film 50 to the front side surface 42 of the first PV cell 40 such that the parts of the surfaces of the wires 58 protruding from the first inner adhesive layer 56 are in contact with the front side surface 42 to facilitate conducting current to or from the front side surface. The first inner adhesive layer 56 is heat activated under pressure to effect bonding of the first inner planar surface 52 of the first film 50 to the front side surface 42 of the first PV cell 40 and at the time of heating to activate the adhesive, the low melting point alloy coating 59 on the protruding surfaces of the wires melts and as a result of the heat and pressure solders the wires into direct ohmic contact with the fingers 45 on the front side surface 42 of the first PV cell 40.

The front side terminal electrode 46 is placed on the front side surface 42 such that the wires 58 extend generally at right angles to the fingers 45 formed thereon. This permits the wires 58 to collect current from a plurality of crossing points along the fingers 45 at which the wires are soldered to the fingers. Referring back to Figures 3 and 4, the wires 58 are terminated in a first busbar 60 which is formed of a strip of tinned copper foil secured to the first extending portion 57 of the first film 50 by the first inner adhesive layer 56 such that it contacts protruding surfaces of the portions of the wires 58 on the first extending portion 57 to make electrical connection therewith. When the first inner adhesive layer 56 is heat activated under pressure, the low melting point alloy coating 59 melts on the protruding portions of the wires 58 and solders the protruding surfaces of the wires 58 to the first busbar 60.

A first contact tab 64 is formed to extend at a right angle to a central portion of the first busbar 60 to allow the front side terminal electrode 46 to be connected to an external electrical circuit. The first busbar 60 has a length approximately equal to the width 51 of the film 50, a width of between about 0.1 mm to about 10mm and a thickness of between about 50μηι to about 200μητι.

The first film 50 also has a first outer adhesive layer 62 on the first outer planar surface 54 and this adhesive layer is used to directly adhesively secure the first outer planar surface of the first film 50 to the inside surface 32 of the front protective sheet 26 shown in Figure 2. This first outer adhesive layer 62 extends entirely across the first outer planar surface 54 and is preferably formed of a thermoplastic adhesive suitable to bond the first outer planar surface 54 to the inside surface 32 of the front protective sheet 26. Suitable thermoplastic adhesives for this purpose include thermally activated ethylene vinyl acetate derivatives or thermoplastic olefin (TPO) produced by Dai Nippon Printing (DNP) Co. Ltd. of Japan or silicon adhesive materials produced by Wacker Chemie AG of Germany, for example, having a softening temperature between about 90°C to about 130°C and a thickness of between about 30 microns to about 100 microns.

Similarly, referring to Figures 5 and 6, the back side terminal electrode 48 is generally the same as the front side terminal electrode but in use is oriented in a direction opposite to the front side terminal electrode. The back side terminal electrode 48 includes a second electrically insulating film 70 which may or may not be optically transparent. Optical transparency is preferable but is not required for the back side terminal electrode since this electrode is connected to the back side 44 of the PV cell (40), which could be, but normally does not need to be exposed to light. The second film 70 is dimensioned to have a width 71 approximately the same as a width of the PV cell on which it is intended to be secured and is dimensioned to have a length 73 slightly longer than a length 75 of the PV cell to which it is to be secured, so that it has a second extending portion 77. Where the PV cell is about 15.5 cm square, the second extending portion 77 may be about 0.5cm to about 1.5 cm, for example.

The second film 70 has second inner and outer planar surfaces shown generally at 72 and 74, respectively. A second inner adhesive layer 76 having the same properties as the first inner adhesive layer 56 is provided on the second inner planar surface 72 and a second plurality of substantially parallel electrically conductive wires 78 lie on the second inner planar surface 72 and are embedded into the second inner adhesive layer 76. The second inner adhesive layer 76 has a thickness less than a thickness of the wires 78 embedded therein such that parts of the surfaces of the wires protrude from the second inner adhesive layer. The surfaces of the wires 78 are pre-coated with a low melting point alloy coating 79, such as described above in connection with Figures 3 and 4, for example. Referring back to Figure 2, the second inner adhesive layer 76 adhesively secures the second inner planar surface 72 of the second film 70 to the back side electrically conductive surface 44 of the first PV cell 40 such that the parts of the surfaces of the wires protruding from the second inner adhesive layer 76 are in contact with the back side surface 44 to facilitate conducting electric current to or from the back side surface. The second inner adhesive layer 76 is heat activated under pressure to effect bonding of the second inner planar surface 72 of the second film 70 to the back side conductive surface 44 of the first PV cell 40 and at the time of heating to activate the adhesive, the low melting point alloy coating 79 on the protruding surfaces of the wires 78 melts and establishes direct ohmic contact between the wires and the back side conductive surface 44 of the first PV cell 40.

Referring back to Figure 5, a second busbar 80 formed of a tinned strip of copper foil is arranged to lie over the surfaces of the wires 78 that protrude from the second inner adhesive layer 76, near a perimeter edge of the second film 70 and is secured to the second inner planar surface 72 by the second inner adhesive layer 76 and is soldered to the exposed portions of the wires 78 such that the wires 78 make electrical contact with the second busbar, when the second inner adhesive layer 76 is heat activated in the same manner as described in connection with the front side terminal electrode (46). The second busbar 80 includes a second contact tab 82 extending at a right angle to a central portion of the second busbar 80 to allow the back side terminal electrode 48 to be connected to the external electric circuit.

A second outer adhesive layer 84 is formed on the second outer planar surface 74 of the second film 70 to directly adhesively secure the second film 70 to the inside surface 36 of the rear protective sheet 28 shown in Figure 2. This second outer adhesive layer 84 is formed of a thermoplastic adhesive or a curable adhesive suitable to bond the second outer planar surface 74 to the inside surface 36 of the rear protective sheet 28, and generally extends across the entire second outer planar surface 74. The rear protective sheet 28 may be formed of a glass or a weather resistant material as described above and the material used as the second outer adhesive layer is selected to bond the second film 70 directly to the material of the rear protective sheet. Suitable thermoplastic adhesives for the above-indicated materials are the same as those described above in connection with the first outer adhesive layer 62 shown in Figures 3 and 4 and in Figure 8.

Referring to Figure 7, PV cell assembly 30 comprising the first PV cell 40 and the front and back side terminal electrodes 46 and 48 is sandwiched between the inside surfaces 32 and 36 of the front and rear protective sheets 26 and 28 respectively.

Referring to Figures 1 and 2, the contact tabs 64 and 82 are connected to first and second contacts 90 and 92 on the frame 24 of the PV module 20 to permit the PV module 20 to be connected to an electrical circuit (not shown).

Generally, the properties of the first and second terminal electrodes are similar and may be generically described as comprising a first electrically insulating optically transparent film having first inner and outer planar surface, a first inner adhesive layer on the first inner planar surface, and a first plurality of substantially parallel, electrically conductive wires on the first inner planar surface and embedded into the first inner adhesive layer. The first inner adhesive layer has a thickness less than a thickness of the wires embedded therein such that parts of surfaces of the wires protrude from the first inner adhesive layer and at least these parts of the surfaces of the wires are coated with a low-melting point alloy. The generic terminal electrode further includes a first busbar on the first inner planar surface, the wires of the first plurality being in electrical contact with the first busbar, a conductor connected to and extending from the first busbar for connecting the first busbar to a circuit, a first, transparent outer adhesive layer on the first outer planar surface of the first film for directly adhesively securing the first film to an inner surface of a first protector, and a first release sheet on the first outer adhesive layer, for preventing the first outer adhesive layer from adhesion when the first inner adhesive layer is being activated. Referring to Figure 8, to make the PV module as described above, the PV cell assembly 30 may be pre-made, i.e. the front and back side terminal electrodes 46 and 48 may be adhesively secured to the front and back side surfaces 42 and 44 respectively, of the PV cell as shown. The front and back side terminal electrodes 46 and 48 may be provided with first and second release sheets 100 and 102 respectively, lightly adhered to the first and second outer adhesive layers 62 and 84 to protect the first and second outer adhesive layers from adhesion when the first and second inner adhesive layers 56 and 76, are being activated.

Referring to Figure 2, the first and second inner adhesive layers 56 and 76 are heat-activated to secure the front side terminal electrode 46 to the front side surface 42 of the first PV cell 40 and to secure the back side terminal electrode 48 to the back side surface 44 of the first PV cell 40. The first and second release sheets 100 and 102 shown in Figure 8, prevent adhesion of the outer adhesive layers 62 and 84 to objects that are or may come into contact therewith during heat activation of the first and second inner adhesive layers 56 and 76. In an alternative embodiment the terminal electrode shown in Figures 5 and 6 can be secured to a PV cell 334 of a terminal PV cell assembly 330 in Figure 13 by heat-activating the second inner adhesive layer 76 while pressing it against the back side surface of the PV cell 334.

Referring back to Figure 8, PV cell assemblies of the type shown at 30 may be pre-manufactured and shipped with the first and second release sheets

100 and 102 covering the first and second outer adhesive layers 62 and 84, respectively. The first and second release sheets 100 and 102 are peeled off of the first and second outer adhesive layers 62 and 84 respectively to expose the first and second outer adhesive layers prior to causing the first and second outer adhesive layers to be placed into contact with the inside surfaces 32 and 36 of the front and rear protective sheets 26 and 28 respectively, as shown in Figure 2. Referring to Figure 7, the PV cell assembly 30 is placed so as to be sandwiched between the front and rear protective sheets 26 and 28 such that the first outer adhesive layer 62 is in contact with the inside surface 32 of the front protective sheet 26 and the first outer planar surface 54 of the first film 50 and such that the second outer adhesive layer 84 is in contact with the inside surface 36 of the rear protective sheet 28 and the second outer planar surface 74 of the second film 70.

Referring to Figures 1 and 2, the contact tabs 64 and 82 are arranged to extend from between the front and rear protective sheets 26 and 28 at edges thereof to facilitate later connection to the first and second contacts 90 and 92.

Referring back to Figure 7, with the PV cell assembly and the front and rear protective sheets 26 and 28 sandwiched together as shown, the front and rear protective sheets essentially define a volume therebetween. To laminate these components into one, the front and rear protective sheets 26 and 28 are pressed together and a vacuum is applied to the volume defined between the front and rear protective sheets to draw out air. The first and second outer adhesive layers 62 and 84 are then heated sufficiently to activate them and thereby bond them to the inside surfaces 32 and 36 of the front and rear protective sheets 26 and 28, respectively.

A laminated panel is thus formed. After heat-activation of the first and second outer adhesive layers 62 and 84, any adhesive that may protrude from perimeter edges of the front or rear protective sheets 26 or 28 is trimmed. If necessary, the perimeter edges of the panel may be sealed using a water tight sealant, for example, and then a frame such as shown at 24 in Figure 1 may be placed around the perimeter edges of the panel and the contact tabs can be connected to the first and second contacts 90 and 92. The frame provides mechanical strength and protects the perimeter edges from environmental conditions such as rain, snow, dust, wind and other deleterious conditions such as shock and sharp objects that can be encountered during shipping, installation or maintenance. The PV module is ready for use.

Multiple Cell Embodiment

Referring to Figure 9, an apparatus according to a second embodiment of the invention is shown generally at 120. This apparatus 120 includes a PV panel 121 comprising a front protective sheet 124, a rear protective sheet (not shown in Figure 9) and a PV cell string assembly shown generally at 122, comprised of four PV cells. The PV cell string assembly 122 is sandwiched between the front and rear protective sheets to form a laminated panel in a manner similar to that shown in Figure 7 and a frame 126 is provided around perimeter edges of the panel to complete the PV module, as shown in Figure 9. Referring to Figure 10, the PV panel 121 is shown in greater detail. The front protective sheet 124 has an inside surface 130 and an outside surface 132. The rear protective sheet 134 has an inside surface 136 and an outside surface 138. As described above, the front protective sheet 124 is transparent and the rear protective sheet 134 can be transparent but need not be. The front protective sheet 124 and the rear protective sheet may be made of glass for example, and the rear protective sheet 134 may be made of a weather resistant material as described above.

The PV cell string assembly 122 includes a PV cell string comprising first, second, third and fourth PV cells 140, 141, 142 and 143. The first PV cell 140 is the first cell of the string. The fourth PV cell 143 may be referred to as an end PV cell as it is the last PV cell in the string, in this embodiment. The first PV cell 140 has a front side electrically conductive surface 144 and a back side electrically conductive surface 146 and the end PV cell 143 has a front side electrically conductive surface 148 and a back side electrically conductive surface 150. These front and back side electrically conductive surfaces 144, 146 and 148, 150 are the same as the front and back side electrically conductive surfaces 42 and 44 described in connection with the first PV cell 40 shown in Figure 2.

Referring back to Figure 10, the PV cell string assembly 122 further includes a plurality of intermediate electrodes 199, 200, 201 for electrically connecting the PV cells 140, 141 , 142 and 143, in series and includes a first terminal electrode the same as the back side terminal electrode 48 shown in Figures 5 and 6, connected to the back side surface 146 of the first PV cell 140 and a second terminal electrode the same as the front side terminal electrode 46 shown in Figures 3 and 4 connected to the end PV cell 143. The first terminal electrode 48 is connected to the back side surface 146 of the first PV cell 140 and acts as a positive terminal (+) of the string and the second terminal electrode 46 is connected to the front side surface 148 of the end PV cell 143 and acts as a negative (-) terminal of the string.

The PV cells 140, 141 , 142 and 143 are arranged and the electrodes 48, 199, 200, 201 and 46 are connected such that the second and first contact tabs 82 and 64 extend parallel to each other and are able to be connected to respective connectors (145 and 147 in Figure 9) on the same edge of the frame 126 of the PV module 120.

The intermediate electrodes 199, 200 and 201 are the same and are depicted by an exemplary intermediate electrode shown at 203 in Figure 11. The exemplary intermediate electrode 203 is formed by electrically and mechanically joining a first electrode portion shown generally at 220 with a second electrode portion shown generally at 222. The first electrode portion 220 is similar to the back side terminal electrode 48 described in Figures 5 and 6, without the contact tab 82, for example, and the second electrode portion 222 is similar to the front side terminal electrode 46 described in Figures 3 and 4 without the contact tab 64, for example.

The first electrode portion 220 includes a first electrically insulating transparent (or non-transparent) film 224 having specifications as described above in connection with the back side terminal electrode 48. The first film 224 is dimensioned to have a width 225 approximately the same as a width of the PV cells (140, 141 , 142, 143 in Figure 10) and is dimensioned to have a length 229 slightly longer than a length of the PV cells, so that it has a first extending portion 233. Where the PV cells (140, 141 , 142, 143 in Figure 10) have a length of about 15.5 cm square, for example, the first extending portion 233 may extend about 0.5 cm to about 1.5 cm longer than the length of a PV cell, for example. The first film 224 has a first inner planar surface 226 and a first outer planar surface 228. A first inner adhesive layer 230 is provided on the first inner planar surface 226 and generally extends entirely across the first inner planar surface. The first inner adhesive layer 230 may be formed of the same material as the first inner adhesive layer 56 described in connection with Figure 3, for example.

The first electrode portion 220 further includes a first plurality of substantially parallel electrically conductive wires 232 lying on the first inner planar surface 226 and embedded into the first inner adhesive layer 230. The first inner adhesive layer 230 has a thickness less than a thickness of the wires 232 embedded therein such that parts of surfaces of the wires protrude from the first inner adhesive layer. The wires 232 are coated with a low melting point alloy 236 such as described above (at 59 in connection with Figures 3 and 4). The first inner adhesive layer 230 and the protruding portions of the wires 232 face upwardly in the orientation shown at 262 in Figure 11. The inner adhesive layer 230 will adhesively secure the first film 224 to the back side surface (e.g. 146) of a PV cell such that parts of the surfaces of the wires 232 protruding from the first inner adhesive layer 230 are in direct ohmic contact with the back side electrically conductive surface of the PV cell to facilitate conducting electric current to or from the back side electrically conductive surface of the PV cell. When the first inner adhesive layer 230 is heat- activated, the first inner adhesive layer 230 bonds the first inner planar surface 226 to the back side surface (146) of the PV cell and the low melting point alloy melts and establishes direct ohmic contact between the protruding surfaces of the wires 232 and the back side surface (146) of a PV cell in contact therewith. A first outer adhesive layer 234 is provided on the first outer planar surface

228 of the first film 224 and a release sheet 235 is provided over the first outer adhesive layer 234 to protect it from activation when the first inner adhesive layer 230 is activated. (The first outer adhesive layer 234 will be used to bond the first outer planar surface 228 to the inside surface (136) of the rear protective sheet (134).)

Still referring to Figure 11 , the second electrode portion 222 includes a second electrically insulating optically transparent film 240 having specifications as described above in connection with the front side terminal electrode 46. The second film 240 is dimensioned to have a width 241 approximately the same as the width of the PV cells (140, 141 , 142 and 143 in Figure 10) and is dimensioned to have a length 245 slightly longer than a length of a PV cell, so that it has a second extending portion 249. The second extending portion 249 is dimensioned to extend beyond a perimeter edge of the PV cell to which it will be attached, by about 0.5 to about 1.5 cm when the

PV cell is about 15.5 cm square.

The second film 240 also has a second inner planar surface 242 and a second outer planar surface 244. A second inner adhesive layer 246 is provided on the second inner planar surface 242 and generally extends entirely across the second inner planar surface. The second inner adhesive layer 246 has the same specifications as the first inner adhesive layer 56 described in connection with the embodiment shown in Figures 3 and 4.

A second plurality of substantially parallel electrically conductive wires 248 lies on the inner planar surface 242 and is embedded into the second inner adhesive layer 246. The surfaces of the wires 248 are coated with a low melting point alloy coating 251 such as described above (at 59 in connection with Figures 3 and 4). The second inner adhesive layer 246 has a thickness less than a thickness of the wires embedded therein such that parts of the surfaces of the second plurality of wires 248 protrude from the second inner adhesive layer 246. The second inner adhesive layer 246 is used to adhesively secure the second film 240 to the front side surface of a PV cell such that parts of the surfaces of the wires 248 protruding from the second inner adhesive layer 246 are soldered to the "fingers" on the PV cell to make direct ohmic contact with the front side surface to facilitate conducting electric current to or from the front side electrically conductive surface of the PV cell to which it is attached. When the second inner adhesive layer 246 is heat- activated, the second inner adhesive layer 246 bonds the second inner planar surface 242 to the front side surface of a PV cell and the low melting point alloy melts and solders the wires 248 to the front side surface thereof.

The second outer planar surface 244 of the second film 240 has a second outer adhesive layer 252 for directly adhesively securing the second outer planar surface of the second film to the inside surface (130) of the front protective sheet (124 in Figure 10). A release sheet 253 is provided over the second outer adhesive layer 252 to protect it from activation when the second inner adhesive layer 246 is activated. (The second outer adhesive layer 252 will be used to bond the second outer planar surface 244 to the inside surface

(130) of the front protective sheet (124).)

In the embodiment shown, a busbar 250 made of a thin strip of tinned copper foil is provided on the second extending portion 249 of the second film 240 such that it is soldered to the portions of the wires 248 on the second extending portion and such that it is secured to the second inner planar surface 242 by the second inner adhesive layer 246. Alternatively, the busbar 250 could be soldered to the portions of the wires 232 of the first plurality of wires that are on the first extending portion 233 of the first film 224 and adhesively secured to the portion of the first inner planar surface 226 on the first extending portion 233 of the first film 224. To join the first and second electrode portions 220 and 222 together to form the intermediate electrode 203 shown in Figure 11 , the first and second electrode portions are arranged such that the wires 232 on the first electrode portion 220 face up and the wires 248 on the second electrode portion 222 face down and such that suitable portions of the extending portions 233 and

249 of the first and second electrode portions overlap. Then, the overlapping portions are pressed together while heating sufficiently to cause the low melting point alloy on the first plurality of wires 232 and the second plurality of wires 248 to become soldered to opposite sides of the busbar 250 to thereby electrically and mechanically connect together the first and second electrode portions to make a single intermediate electrode 203 as shown.

Generally, the intermediate electrode may be described as having a first electrode portion comprising a first electrically insulating optically transparent film having first inner and outer planar surfaces, a first inner adhesive layer on the first inner planar surface, and a first plurality of substantially parallel, electrically conductive wires on the first inner planar surface and embedded into the first inner adhesive layer. The first inner adhesive layer and the first plurality of wires face in a first direction, and the first inner adhesive layer has a thickness less than a thickness of the wires embedded therein such that parts of surfaces of the wires protrude from the first inner adhesive layer. Parts of the surfaces of the wires are coated with a low-melting point alloy. The first electrode portion further includes a first busbar on the first inner planar surface, the wires of the first plurality being in electrical contact with the first busbar. A first outer adhesive layer is provided on the first outer planar surface of the first film for directly adhesively securing the first film to an inner surface of a rear protective sheet, and a first release sheet is provided on the first outer adhesive layer, for preventing the first outer adhesive layer from adhesion when the first inner adhesive layer is being activated. The intermediate electrode further includes a second electrode portion adjacent the first electrode portion. The second electrode portion comprises a second electrically insulating optically transparent film having second inner and outer planar surfaces, a second inner adhesive layer on the second inner planar surface and a second plurality of substantially parallel, electrically conductive wires on the second inner planar surface and embedded into the second inner adhesive layer. The second inner adhesive layer and the second plurality of wires face in a direction opposite to the first direction, and the second inner adhesive layer has a thickness less than a thickness of the wires embedded therein such that parts of surfaces of the wires protrude from the second inner adhesive layer and wherein at least the parts of the surfaces of the wires are coated with a low-melting point alloy. The wires of the second plurality are in electrical contact with the first busbar to electrically connect the first and second pluralities of wires together. The second electrode portion further includes a second transparent outer adhesive layer on the second outer planar surface of the second film for directly adhesively securing the second film to an inner surface of a front protective sheet, and a second release sheet on the second outer adhesive layer, for preventing the second outer adhesive layer from adhesion when the second inner adhesive layer is being activated.

Referring to Figure 12, for ease of manufacturing an intermediate cell assembly 300 is formed by attaching an intermediate electrode of the type shown at 203 in Figure 11 to a PV cell 302. Referring back to Figure 10, in the embodiment shown there are three such intermediate cell assemblies: a first

PV cell assembly 304 is provided by the first intermediate electrode 199 attached to the first PV cell 140, a second PV cell assembly 306 is provided by the second intermediate electrode 200 attached to the second PV cell 141 and a third PV cell assembly 308 is provided by the third intermediate electrode 201 attached to the third PV cell 142. A terminal PV cell assembly

310 comprised of the second terminal electrode 46 attached to the fourth PV cell 143 is also provided and will be described later with reference to Figure 13. Referring to Figure 12, in the embodiment shown, the second inner planar surface 242 of the second electrode portion 222 of the intermediate electrode 203 is adhesively secured by the second inner adhesive layer 246 to a front side electrically conductive surface 312 of the PV cell 302 by heat-activating the second inner adhesive layer 246. At the same time, the heat melts the low melting point alloy coating 251 on the wires 248 protruding from the second inner adhesive layer 246, and solders them to fingers 314 extending transversely across the front side surface 312. The second inner adhesive layer 246 and the low melting point alloy coating 251 electrically and mechanically connect the second electrode portion 222 to the front side surface 312 of the PV cell 302. It will be appreciated that the release sheet 253 is kept in place on the second outer adhesive layer 252 while the second electrode portion 222 is being heated to activate the third inner adhesive layer 246 and melt the low melting point alloy, as this avoids exposing the second outer adhesive layer 252 to foreign objects which could adhere to the second outer adhesive layer when heat is applied to activate the second inner adhesive layer 246. The first electrode portion 220 extends beyond a perimeter edge 316 of the

PV cell 302 and defines an area 303 on which another PV cell similarly attached to a similar intermediate electrode for example, or similarly attached to a terminal electrode, for example, can be placed, to connect to a back side of such other PV cell, to thereby electrically and mechanically connect together the PV cell 302 to an adjacent PV cell in the string, as shown in

Figure 10. The first, second and third PV cell assemblies 304, 306 and 308 and the terminal PV cell assembly are connected together in this way.

Generally, an intermediate PV cell assembly may be described as comprising the intermediate electrode apparatus described in connection with Figure 11 and further comprising a PV cell having an electrically conductive front side surface and an electrically conductive back side surface, the electrically conductive front side surface having current collection contacts thereon and wherein the second inner adhesive layer of the intermediate electrode apparatus adhesively secures the second film thereof to the front side electrically conductive surface of the PV cell and wherein the low melting point alloy coating on the parts of the surfaces of the wires protruding from the second inner adhesive layer of the intermediate electrode apparatus are in direct ohmic contact with the front side electrically conductive surface to facilitate conducting electric current to or from the front side electrically conductive surface of the PV cell. Referring to Figure 13, a generic front side terminal PV cell assembly is shown generally at 330 and includes a terminal electrode of the type shown at 46 in Figures 3 and 4 attached to a PV cell 334. Generally, the front side terminal PV cell includes the first terminal electrode apparatus as described in connection with Figures 3 and 4 and further comprises a PV cell having an electrically conductive front side surface and an electrically conductive back side surface, the electrically conductive front side surface having current collection contacts thereon and wherein the first inner adhesive layer adhesively secures the first film to the front side electrically conductive surface of the PV cell and wherein the low melting point alloy solders the parts of the surfaces of the wires protruding from the first inner adhesive layer into direct ohmic contact with the current collection contacts on the front side electrically conductive surface to facilitate conducting electric current to or from the front side electrically conductive surface. In the embodiment shown, the first inner planar surface 52 of the first film 50 of the terminal electrode 46 is adhesively secured by the first inner adhesive layer 56 to a front side electrically conductive surface 336 of the PV cell 334 by heat activating the first inner adhesive layer 56. At the same time, the heat melts the low melting point alloy 59 on the wires 58 protruding from the first inner adhesive layer 56, soldering them to fingers 338 extending transversely across the front side surface 336. The first inner adhesive layer 56 and the low melting point alloy electrically and mechanically connect the first film 50 to the front side surface 336 of the PV cell 334. It will be appreciated that the release sheet 100 is kept in place on the first outer adhesive layer 62 while the first film 50 is being heated to activate the first inner adhesive layer 56 and melt the low melting point alloy coating 59, as this avoids exposing the first outer adhesive layer 62 to foreign objects which could adhere to the first outer adhesive layer when heat is applied to heat activate the first inner adhesive layer 56 and to solder the wires 58 to the front side surface 336. The terminal electrode 332 is thus attached to the front side surface 336 of the PV cell 334. A back side surface 337 of the PV cell 334 is left open and unconnected. Generally, a generic front side terminal PV cell assembly may be described as comprising the first terminal electrode apparatus described in connection with Figures 3 and 4 and further comprising a PV cell having an electrically conductive front side surface and an electrically conductive back side surface, the electrically conductive front side surface having current collection contacts thereon and wherein the first inner adhesive layer on the first terminal electrode apparatus adhesively secures the first film to the front side electrically conductive surface and wherein the low melting point alloy coating solders the parts of the surfaces of the wires protruding from the first inner adhesive layer into direct ohmic contact with the current collection contacts on the front side electrically conductive surface to facilitate conducting electric current to or from the front side electrically conductive surface.

Making a PV Cell String Assembly

Referring back to Figure 10, to manufacture PV cell string assemblies of the type shown in Figure 10, a process is provided with a plurality of terminal electrodes such as shown at 48 in Figure 5, a plurality of PV cell assemblies of the type shown at 300 in Figure 12 and a plurality of terminal PV cell assemblies of the type shown at 330 in Figure 13. Referring to Figure 14, to make a PV cell string assembly of the type shown in

Figure 10, the manufacturing process begins by laying on a flat surface 340 a first terminal electrode 48 such that the wires 78 face upwardly. The release sheet shown at 102 in Figure 14 is left intact and is thus flat planar on the flat surface 340, protecting the second outer adhesive layer 84.

Next, referring to Figure 15, the first PV cell assembly 304 is placed such that the back side surface 146 of the first PV cell 140 rests on the wires 78 of the terminal electrode 48 and such that the wires 78 extend all across the back side surface of the first PV cell. This leaves the first electrode portion 220 unconnected with its wires 232 facing upwardly, ready to support the back side surface of a PV cell of the next PV cell assembly (306 in Figure 10) in the string.

Referring to Figure 16, the second PV cell assembly 306 is placed such that a back side surface 149 of the second PV cell 141 rests on the wires 232 of the first electrode portion 220 of the first intermediate electrode 199 and such that the wires extend all across the back side surface of the second PV cell 141 . In the embodiment shown, because the back side surfaces of the PV cells are completely conductive, the back side surfaces of the cells can be laid in any orientation on the wires of the adjacent third electrode portion to which they are to be connected. This allows the forming of the PV cell string assembly to easily be selectively propagated parallel to or perpendicular to the orientation of the immediately previously placed PV cell assembly. More particularly, as shown in Figure 16 this allows a PV cell string assembly to be formed such that the terminal electrodes 46 and 48 are adjacent to each other so that when the string is used in a PV panel, the distance from the contact tabs 82 and 64 to connectors (145 and 147 in Figure 9) on the PV panel and, hence, resistive losses can be kept to a minimum.

By following a process of placing a back side surface of a PV cell (e.g. 302 in Figure 12) of a PV cell assembly (e.g. 300 in Figure 12), on the upwardly facing wires (e.g. 232 in Figure 15) of the first electrode portion (e.g. 220 in Figure 15) of a preceding already placed PV cell assembly, the PV cells of each PV cell assembly are arranged mechanically and electrically in series, forming a series string of interconnected PV cells. While the embodiment shown depicts four PV cells connected in series, it now will be readily apparent that a PV string of any number of PV cells can be made by following the process described above.

Referring back to Figure 16, the string is finally terminated by placing a back side surface 150 of the PV cell 143 of the terminal PV cell assembly 330 on the upwardly facing wires 232 of the first electrode portion (220) of the third intermediate electrode 201 such that the contact tab 64 on the first film (50) extends adjacent and parallel to the contact tab 82 on the second film (70) of the second terminal electrode 48.

The series string is shown in Figure 16 with the second terminal electrode 48, the PV cell assemblies 304, 306, 308 and the terminal PV cell assembly 330 simply laid out as shown, with release sheets 253 and 100 on outer adhesive layers 252 and 62 and release sheets 102 and 235 on back side outer adhesive layers 84 and 234. The inner adhesive layers 230 and 76 and protruding portions of the wires 232 and 78 are exposed and are directly in contact with corresponding back side surfaces of the PV cells to which they are to be attached. Attachment of the inner adhesive layers 76 and 230 exposed and directly in contact with corresponding back side surfaces of the PV cells 140, 141 , 142, 143 is effected by heating the inner adhesive layers in contact with the back side surfaces of respective PV cells sufficiently to activate the inner adhesive layers and to melt the low melting point alloy coatings (79, 236) on the protruding portions of the wires embedded in the inner adhesive layers such that the pluralities of wires establish direct ohmic contact with the back side surfaces of respective PV cells and such that the inner adhesive layers bond respective electrode portions to the back side surfaces of respective PV cells. The string is thus mechanically and electrically connected together.

In the embodiment shown in Figures 9-16, the PV string starts with a terminal electrode 48, employs PV cell assemblies of the type shown at 300 in Figure 12 in which electrodes are pre-connected to the front side surfaces of PV cells and employs a terminal PV cell assembly of the type shown at 330 in Figure 13, in which the final electrode is connected to the front side surface of the final PV cell in the string. In this embodiment, the front side surfaces of all of the PV cells used in the string are pre-connected to electrodes and the electrodes are connected to adjacent back side surfaces of adjacent PV cells when the string is made by heating and pressing.

Generically, the PV string of this embodiment may be described as comprising the terminal electrode 48 described in connection with Figures 5 and 6, a plurality of intermediate PV cell assemblies as described in connection with Figure 12 connected in series order, wherein the first inner adhesive layer of the terminal electrode 48 is bonded to a back side surface of a PV cell of a first one of the intermediate PV cell assemblies and wherein the low melting point alloy coating on the protruding portions of the wires embedded in the first inner adhesive layer of the first terminal electrode is in direct ohmic contact with the back side surface of the PV cell of the first intermediate PV cell assembly. The PV string further includes a terminal PV cell assembly as described in connection with Figure 13 wherein the first inner adhesive layer of the first electrode portion of a final intermediate electrode assembly of the plurality of intermediate electrode assemblies is bonded to a back side electrically conductive surface of a PV cell of the terminal PV cell assembly and wherein the low melting point alloy coating on the protruding portions of the wires embedded in the first inner adhesive layer of the final intermediate electrode assembly is in direct ohmic contact with the back side surface of the PV cell of the terminal PV cell assembly, and wherein starting with the first intermediate PV cell assembly, the back side surfaces of PV cells of subsequent intermediate PV cell assemblies are bonded by respective first inner adhesive layers to the first inner planar surfaces on immediately prior PV cell assemblies and the low melting point alloy coating on respective pluralities of wires embedded in the respective first inner adhesive layers is in direct ohmic contact with the back side surfaces of respective subsequent intermediate PV cell assemblies, to connect the plurality of intermediate PV cell assemblies together, between the terminal electrode and the terminal PV cell assembly.

Making a Panel After making a PV string assembly as shown at 122 in Figure 16, the outer adhesive layers 252 and 62 of respective electrode portions adjacent front sides of the PV cells are still covered with release sheets 253 and 100 and the outer adhesive layers 84 and 234 are still covered by release sheets 102 and 235. The string forms a unitary PV cell string assembly but it is not secured to anything. To secure the string, the release sheets 253 and 100 on the outer adhesive layers 252 and 62 adjacent the front side surfaces of the PV cells in the string are peeled away and the string is placed (by robotic manufacturing equipment for example) face down (not shown) on the inside surface 130 of the front protective sheet 124 shown in Figure 10, such that the outer adhesive layers 252 and 62 are in direct contact with the inside surface 130 of the front protective sheet 124. Then, with the PV string still upside down, the release sheets 102 and 235 on the outer adhesive layers 84 and 234 adjacent the back side surfaces of the PV cells in the string are peeled away and the rear protective sheet 134 is placed on these outer adhesive layers 84 and 234 such that the inside surface 136 of the rear protective sheet 134 is directly in contact with these outer adhesive layers. Thus, the string assembly 122 and associated PV cell assemblies are sandwiched between inside surfaces 130 and 136 of the front and rear protective sheets 124 and 134.

The contact tabs 64 and 82 are positioned to extend in relatively close proximity to each other and from between the front and rear protective sheets 124 and 134 so that they will be accessible outside of the front and rear protective sheets to permit connecting the resulting PV module to an electrical circuit.

A vacuum is then applied to remove air from between the front and rear protective sheets 124 and 134 and, at the same time, the front and rear protective sheets are pressed together while heat is applied to activate the outer adhesive layers 252, 62, 84 and 234 to directly adhesively secure e.g.

"bond" the corresponding electrode portions directly to the inside surfaces 130 and 136 of the front and rear protective sheets 124 and 134. The PV panel 121 shown in Figure 10 is thus formed. Any adhesive that may leak out during the process of heating and pressing may be trimmed and any voids in the adhesive along edges of the panel may be filled with a sealer, for example, to ensure the edges of the panel will be airtight and watertight. The frame shown at 126 in Figure 9 may then be secured around the edges of the panel, taking care to first connect the contact tabs (82 and 64) extending from an edge of the panel to the connectors 145 and 147 on the frame 126 to allow the PV cell string assembly 122 to be connected to an electrical circuit.

Alternative PV Cell String Assembly

Whereas in the embodiment described in connection with Figures 9 - 16 the PV cell assemblies were pre-formed with electrodes pre-connected to front side surfaces of PV cells before the string is made, alternatively the electrodes can be pre-connected to back side surfaces of the PV cells as described in connection with Figures 17 - 19. As shown in Figures 17 to 19, an alternative PV string 400 may start with a front side terminal electrode of the type shown at 46 in Figures 3 and 4. Then intermediate PV cells are connected together using PV cell assemblies of the type shown at 402 in Figure 18 in which the back side surface 404 of the PV cell 406 in each assembly 402 is pre-connected to the first electrode portion 220 of the intermediate electrode shown at 203 in Figure 11 and the second electrode portion 222 is left unconnected until heated and pressed onto a front surface of a PV cell of an adjacent PV cell assembly during formation of the string. Generally the intermediate PV cell assemblies in this embodiment can be described as comprising the intermediate electrode apparatus described in connection with Figure 11 and further comprising a PV cell having an electrically conductive front side surface and an electrically conductive back side surface, the electrically conductive front side surface having current collection contacts thereon for collecting current from the PV cell and wherein the second inner adhesive layer of the intermediate electrode adhesively secures the second film to the front side electrically conductive surface of the PV cell and wherein the low melting point alloy coating solders the parts of the surfaces of the wires protruding from the second inner adhesive layer into direct ohmic contact with the current collection contacts on the front side electrically conductive surface to facilitate conducting electric current to or from the front side electrically conductive surface.

Referring to Figure 19, the alternative string is terminated by a final PV cell assembly 408 in which an electrode of the type shown at 48 in Figures 5 and 6 is pre-connected to a back side surface 410 of a PV cell 412. Generally, the final or terminal PV cell assembly of this embodiment may be described as comprising the terminal electrode apparatus as described in connection with Figures 5 and 6 and further comprising a PV cell having an electrically conductive front side surface and an electrically conductive back side surface, and wherein the inner adhesive layer of the terminal electrode adhesively secures the film thereof to the back side electrically conductive surface of the PV cell and wherein the low melting point alloy coating on the parts of the surfaces of the wires protruding from the inner adhesive layer are in direct ohmic contact with the back side electrically conductive surface of the PV cell to facilitate conducting electric current to or from the back side electrically conductive surface.

Referring back to Figure 17, in this embodiment all of the back side surfaces 420, 422, 424, and 426 of the PV cells 428, 430, 432, and 434 are pre- connected to the first electrode portions 220 of the intermediate PV assemblies and the inner planar surface 72 of the terminal electrode 48 of the final PV cell assembly respectively. The first inner planar surface 52 of the terminal electrode 46 and second electrode portions 222 of the intermediate electrodes (203) of the intermediate PV assemblies 402 are connected to front side surfaces of adjacent PV cells at the time of manufacturing the string, in a manner similar to that described above.

Referring to Figure 17, when making a PV string according to this embodiment, the terminal electrode 46, PV cell assemblies 402 and terminal PV cell assembly 408 are laid down on a flat surface upside down, i.e. with front sides of the PV cell of the PV cell assemblies facing down on the terminal electrode 46 and respective second electrode portions 222. Then, the inner adhesive layers on the unattached first inner planar surface 52 of the terminal electrode 46 and the inner surfaces (242) of the second electrode portions 222 of the PV cell assemblies are heat- activated to secure these surfaces to respective front side surfaces 427, 429, 431 and 433 of the PV cells 428, 430, 432 and 434, while at the same time melting the low melting point alloy coating on respective pluralities of wires, on the respective unattached inner surfaces of the terminal electrode 46 and second electrode portions 222 causing the wires (58 and 248) protruding from the inner adhesive layers (56 and 246) to be soldered to the front side surfaces 427, 429, 431 and 433 of the PV cells they contact. The adhesive layers (56 and 246) and low melting point alloy coatings (59 and 251) mechanically and electrically connect the PV cells to the inner planar surface 52 of the terminal electrode 46 and the inner planar surfaces (242) of the second electrode portions 222 of the intermediate electrodes (203). The string is thus completed and the process of making a panel by placing the string between first and second protective sheets such as front and rear protective sheets (124 and 134 in Figure 10) and heat activating the outer adhesive layers (62 and 252) can be completed as described under the heading "Making a Panel", above.

Generally, the PV string in this embodiment may be described as comprising the terminal electrode described in connection with Figures 3 and 4, or 5 and 6 a plurality of intermediate PV cell assemblies as described in connection with Figure 18 wherein the first inner adhesive layer of the terminal electrode is bonded to the front side surface of a PV cell of a first one of the intermediate PV cell assemblies and wherein the wires embedded in the first inner adhesive layer of the terminal electrode are soldered to the front side surface of the PV cell of the first one of the intermediate PV cell assemblies by the low melting point alloy coating on the protruding portions of the wires embedded in the first inner adhesive layer of the first terminal electrode. The PV string further includes a terminal PV cell assembly as described in connection with Figure 19 wherein a second inner adhesive layer of a second electrode portion of a final intermediate electrode assembly of the plurality of intermediate electrode assemblies is bonded to the front side electrically conductive surface of the PV cell of the terminal PV cell assembly of Figure 19 and wherein the wires embedded in the second inner adhesive layer of the terminal electrode are soldered to the front side surface of the PV cell of the terminal PV cell assembly by the low melting point alloy coating on the protruding portions of the wires embedded in the second inner adhesive layer of the final intermediate PV cell assembly. Starting with the first intermediate PV cell assembly, the front side surfaces of PV cells of subsequent intermediate PV cell assemblies are bonded by respective second inner adhesive layers on immediately prior PV cell assemblies and respective pluralities of wires embedded in the respective second inner adhesive layers are soldered to the front side surfaces of the subsequent intermediate PV cell assemblies by the low melting point alloy coating on the protruding surfaces of the wires to connect the plurality of intermediate PV cell assemblies together, between the terminal electrode and the terminal PV cell assembly.

Generally a PV panel may be made using a) the single cell arrangement as shown in Figures 1-8; or b) a double cell arrangement employing the first terminal electrode shown in Figures 5 and 6, a single intermediate PV cell assembly as shown in Figure 12 and a terminal PV cell assembly as shown in Figure 13; or c) a double cell arrangement employing the first terminal electrode shown in Figures 3 and 4, a single intermediate PV cell assembly as shown in Figure 18 and a terminal PV assembly as shown in Figure 19; or d) the PV string described in Figures 12 - 16; or e) the PV string described in Figures 17 - 19 and front and rear protective sheets, wherein at least the front protective sheet is transparent to admit light therethrough, and wherein each of the front and rear protective sheets has an inside surface and an outside surface, and wherein the PV string is sandwiched between the front and rear protective sheets and wherein the outer adhesive layers of the electrodes are adhesively bonded to at least one of the inside surfaces. The present invention employs adhesive layers of suitable thickness on the outer surfaces of the electrodes used to connect the PV cells of PV cell assemblies within the module together, to secure such outer surfaces directly to inside surfaces of front and rear protective sheets of a PV panel used in a PV module. This eliminates the use of conventional separate sheets of encapsulant materials during lamination, thereby reducing the cost of the final PV module.

In addition, the use of adhesive layers directly on the electrodes instead of separate sheets of encapsulant material during lamination enables PV modules to have a lesser thickness than conventional modules and allows the lamination process to be completed faster than with encapsulant materials. This results in higher production capacity, lower energy consumption, lower production costs and higher profits.

In addition, the use of adhesive layers directly on the electrodes instead of separate sheets of encapsulant material during lamination results in better heat dissipation from the PV module due to smaller distances between the PV cells and the rear protective sheet than are present when encapsulant material is used. This means that the normal operating cell temperature of the PV module is decreased, resulting in a gain in conversion of energy, resulting in higher profits and a higher return on investment. For example, in one embodiment, the normal operating cell temperature (NOCT) of the PV module was found to be at least 3 degrees Celsius lower than if the same module were made without adhesive directly on the electrodes and the lamination were made with encapsulant material. In this embodiment a 3 degree reduction in NOCT would produce about a 1.5% absolute gain in annual kWh energy production. While specific embodiments of the invention have been described and illustrated, such embodiments should be considered illustrative of the invention only and not as limiting the invention as construed in accordance with the accompanying claims.