ASSEMBLY METHOD AND COMBINED BIVALENT STATION FOR PHOTOVOLTAIC PANELS

Abstract

An assembly method and a combined and bivalent workstation for automatically assembling photovoltaic panels, with printing of ECA on cell portions and progressive arrangement with a partial superimposition on the contacts, pre-forming shingled strings in a continuous cycle, which are ready for loading on a backsheet, without dry-curing. The method provides a macro-phase of lay-up entirely made in the station, with simultaneous and coordinated sub-phases: picking of portions with a first handler and control, oriented loading on a vacuum belt, control of positioning on the belt, printing of ECA, control of printing and positioning, progressive superimpositions on a shuttle-tray with bidirectional translation coordinated with a second handler with chocked vacuum, picking of the shingled string with a third handler, control of string alignment, loading and pre-fixing. Vision systems are integrated for the execution of said sub-phases.

Claims

1. Automatic assembly method for making photovoltaic panels with cells of crystalline silicon of the traditional type with top-bottom contacting, that is to say, with the positive and negative electrical contacts placed on opposite faces of the same cell, interconnected with a partial superimposition, that is to say, shingled, being entire or subdivided into portions identical to each other called equivalent cell portions, said assembly method including a first phase of positioning of a backsheet with an encapsulating layer on a panel-holding tray that horizontally crosses the workstations of an automatic plant, and including a following macro-phase of printing of ECA conductive adhesive on the electrical contacts of said cells or portions also comprising the loading and pre-fixing on the encapsulating layer of the backsheet, then including a phase of superimposition of an upper encapsulating layer, then a phase of laying of the front glass, and finally a phase of overturning of the panel for sending it to the rolling furnace; said assembly method being characterised in that in the macro-phase said portions are pre-arranged in shingled strings according to a macro-phase of lay-up in which ECA is printed on the upward-facing contacts of said portions after picking them from a box, spacing them apart and laying them on a pneumatic belt, and wherein then in said macro-phase a printed portion is individually laid onto another in a superimposition on said contacts in such a way as to progressively pre-arrange in a continuous cycle shingled strings, which are complete and ready to be loaded and pre-fixed on said backsheet; said printing of ECA on said portions, said pre-arrangement of said shingled strings and said loading with pre-fixing on said backsheet being simultaneously carried out by means of said macro-phase in one single automatic and multi-function workstation called combined station of lay-up; said pre-arrangement of shingled strings being performed with an integrated system of means comprising at least one mobile support of the shuttle-tray type with a bidirectional back-forth translation with vacuum for holding, and a robotic handler coordinated with it in the movements being provided with a pneumatic gripping hand with independent sections, with chocked vacuum channels for picking said just printed equivalent cell portions by groups and releasing them one at a time by laying them in a partial superimposition on said shuttle-tray that moves in a synchronized way like a plotter, in such a way as to progressively form in both directions of translation said shingled string ready to be picked as an entire, transported, oriented, laid and pre-fixed on said encapsulating layer of the backsheet with a handler of the Cartesian bridge type intended to apply pneumatic vacuum and localised heating on each equivalent cell portion.

2. Automatic assembly method according to claim 1, characterised in that said macro-phase of lay-up comprises the following sub-phases, which are simultaneous and coordinated with respect to each other: (1) picking with a first handler said equivalent cell portions from a box where they are stacked and spaced next to each other, with the control of the actual positioning once picked, and check for any possible cracks and/or non-compliances; (2) loading on a vacuum belt with the contacts facing upwards, with said first handler, subject to the alignment of each portion; (3) control of the actual position and checks; (4) printing of ECA on the contacting points; (5) printing quality control and detection of the actual position, and checks; (6) progressive superimpositions on said pneumatic shuttle-tray, with a second handler coordinated with it and provided with said vacuum gripping hand with independent sections; (7) picking and transport of the shingled string with a third handler with a Cartesian portal with said gripping and localised heating means acting on each portion; (8) control of the head-tail alignment of the shingled string; (9) oriented loading of the shingled string on the backsheet and immediate pre-fixing, with stationary optical references; optional unloading of the cracked and/or non-compliant cells subject to an automatic optical control after the first and/or fifth sub-phase, as an alternative the second and/or sixth sub-phase; optional unloading of the non-compliant strings subject to an automatic optical control after the eighth sub-phase, as an alternative the ninth sub-phase.

3. Automatic assembly method, according to claim 2, characterised in that in said macro-phase of lay-up multiple shingled strings are being simultaneously processed providing a pair of said bidirectional shuttle-trays identical and parallel to each other, which translate back and forth in an independent but coordinated way with respect to each other and to the other equipment of the station to progressively form in a continuous cycle said shingled string on a shuttle-tray while said third handler picks from the other shuttle-tray the previously completed shingled string and transports it to lay it on said backsheet, with a preparatory operating logic.

4. Automatic assembly method according to claim 1, characterised in that after said macro-phase of lay-up, there is a phase of bussing wherein said shingled strings are electrically interconnected.

5. Automatic assembly method according to claim 4, characterised in that said phase of bussing is carried out on shingled strings previously loaded and pre-fixed alternating the head polarities of adjacent strings in such a way as to simplify the path of the applied conductive elements.

6. Combined and bivalent workstation, for the automatic assembly of photovoltaic panels with traditional cells with positive and negative electrical contacts on the opposite faces of the same cell, or with said back-contact cells, providing means and functions integrated to and combined with each other in such a way as to operate in a continuous cycle according to said automatic assembly method, as in claim 1, characterised in that in order to perform said macro-phase with said traditional cells, entire or subdivided into equivalent cell portions, an automatic shingling apparatus is provided, which is intended to continuously pre-form said shingled strings starting from said equivalent cell portions interconnected in a partial superimposition on said contacts, which interacts and is coordinated with a multi-function handling equipment called third handler, which picks the entire shingled string as soon as it is made to load it and pre-fix it in an oriented way on said encapsulating layer of the backsheet; said shingling apparatus comprising at least the following means: a loading path of the boxes, with spacers, containing the stacked equivalent cell portions; a first handler, of the robotic type on one single line or with a multi-line Cartesian portal, interposed between said loading path and a loading belt that leads to the printer, with a gripping means of the vacuum plate type shaped according to said portions; said loading belt being provided with vacuum for holding said portions (403) translating them first into the correct position for printing (205, 206) and then into the picking position (208, R2); a flat silkscreen printer, crossed by said belt, comprising a processing area for laying ECA on the portions; a second handler of the robotic type with an orientable gripping hand, with independent sectors with chocked vacuum channels, interposed between said picking position and the loading position on a mobile shuttle-tray coordinated with it; a shuttle-tray for supporting and holding the shingled string being made, which translates in a bidirectional back and forth way on a rectilinear axis in a coordinated way with respect to said second handler, with an end-of-stroke stop in correspondence of the picking position where it is interfaced with said third handler; and wherein said third handler is a Cartesian portal with a pneumatic gripping hand corresponding to the entire shingled string, of the plate type provided with holes with activable vacuum on each of its portions or an equivalent system of the gripper or micro suction cups type, also with heating means for the localised pre-fixing of each portion which are alternatively matched with or incorporated to it.

7. Combined and bivalent workstation, according to claim 6, characterised in that said means operate with the aid of at least one first, second and third vision system, with control cameras and/or automated optical inspection means, so integrated and grouped in said combined station according to the function: said first system, in correspondence of said first handler and before the printer, for controlling the position and related alignments of said portions, and for detecting any cracks and/or non-compliances; said second system, in correspondence of said second handler and after the printer for controlling quality printing and the correct position of the contacting points with respect to the edge, and for detecting any cracks and/or non-compliances; said third system, in correspondence of said third handler, for detecting first the alignment of the shingled string with two acquisitions, on the first and on the last cell, and then the stationary reference points on the backsheet for the correct final positioning, and for detecting any cracks and/or non-compliances.

8. Combined and bivalent workstation, according to claim 7, characterised in that in order to assemble a back-contact panel, said automatic apparatus prints and loads on said shuttle-tray entire back-contact cells next to each other, that is to say, not superimposed and not electrically interconnected by strings, in such a way that said third handler, after overturning them, can load them and pre-fix them on a conductive backsheet, passing directly to the station where the upper encapsulating layer is superimposed and skipping the bussing station.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0073] FIG. 1 schematically shows the assembly method of a photovoltaic panel with back-contact architecture according to the known art, as for example in ITTV2017A084020 (Baccini et al.), called D8 in the above-mentioned description of the prior art, wherein the laying of said ECA is combined to the loading with pre-fixing of the cells, silkscreen printing the conductive material on the contacts of the cell facing upwards and immediately loading the printed cells according to a single macro-phase of cell printing, loading and pre-fixing, which provides six simultaneous operative and coordinated sub-phases: oriented loading, printing, control, overturning, positioning and pre-fixing of the cell on the encapsulating layer with localised heating.

[0074] FIG. 2 schematically illustrates the assembly method proposed by the invention, relating to a photovoltaic panel with cells or equivalent cell portions of traditional type, interconnected with a partial superimposition on the contacts, namely shingled, according to a single macro-phase of printing (11), pre-arrangement of complete shingled strings on a shuttle-tray with bi-directional translation, picking with loading and pre-fixing of the strings, according to nine main operative sub-phases (11.1 11.9) that are simultaneous and coordinated one another, with possible reject of non-conform cells or strings (11.c, 11.S).

[0075] FIG. 3 is a flow-like schematic illustration of said macro-phase (11), wherein a particular automatic apparatus (20) allows to pre-arrange said alternated shingled strings, which are ready to be immediately loaded and pre-fixed on the backsheet (R3), in the same workstation (S2).

[0076] FIGS. 4a and 4b are orthogonal views of the automatic plant object of the invention, respectively in X-X longitudinal section (FIG. 4a) and in plan (FIG. 4b), wherein the combined station (S2) where said macro-phase (11) is executed is enclosed by a dashed box, as in the following FIGS. 5a and 5b.

[0077] FIGS. 5a and 5b are plan views of said combined and bivalent station (S2) object of this invention, respectively an overall view (FIG. 5a) and an enlarged detailed view (FIG. 5b), in the dashed box, which refers to the automatic shingling apparatus (20) suitable to print cell portions and immediately pre-arrange them with a partial superimposition for forming shingled strings, which are ready to be loaded and pre-arranged on a backsheet in transit in the same combined station that operates in a continuous cycle and in an integrated way. It is shown a basic embodiment with a single path for loading the cells, or equivalent cell portions, and a single shuttle-tray for forming the string.

[0078] FIG. 6 schematically illustrates a plan view of a box container of equivalent cell portions, which in the example is a cell divided in four identical portions like slices, which are stacked and spaced in a calibrated way for the purpose of the printing. The invention allows, with the same logic, to process an entire cell or any number of equivalent cell portions, which is for example divided in halves, fourth, sixth, eighth or other subdivisions required for a specific panel to be produced.

[0079] FIG. 7 schematically illustrates a vertical section of a particular handling end member of the second robot (R2), according to this invention, which is provided with chocked vacuum with independent sectors for the partial superimposition between equivalent cell portions;

[0080] FIGS. 8a and 8b are simplified schematic views concerning the progressive superimposition of said equivalent cell portions when forming a shingled string, by means of a handler (R2) equipped with a gripping hand with chocked vacuum with independent sectors, which releases the equivalent cell portions one by one, on a shuttle-tray that translates, in a bi-directional way and coordinated to it, operating both to-and-fro, wherein at the return of the shuttle-tray (FIG. 8b) the direction of superimposition is opposite to that of forward (FIG. 8a), reciprocating the head direction, namely the first laid cell, to facilitate the production and the bussing contact between near strings.

[0081] FIGS. 9a and 9b are views of said combined and bivalent station (S2) object of this invention, respectively a plan view (FIG. 9a) and a raised view (FIG. 9b) according to the section line Y-Y, in the preferred embodiment with high productivity, with double initial loading path and double shuttle-tray wherein shingled strings are formed to-and-fro; in this case, the first handler suitable to load the cell equivalent portions from the containers is of the Cartesian portal type (R1b) and transversely acts on both initial loading paths serving the central pneumatic belt. Vision systems are here indicated in detail at each detection point (AOI1, TC1-TC7). The third handler (R3), with Cartesian portal, provides a multifunction gripping device that simultaneously performs both the loading and the immediate pre-fixing by acting on each portion of the string, which is conventionally shown as dashed in the initial position of picking of the string, namely on the end-of-stroke stop of the shuttle-tray.

DESCRIPTION OF AT LEAST ONE EMBODIMENT OF THE INVENTION

[0082] With reference also to the figures (FIGS. 2-9b), a method (10) is described, which comprises a macro-phase (11) for advantageously assembling photovoltaic panels (400) with crystalline silicon solar cells of the traditional type with top-bottom contacting, or cell portions that are identical one another (403a-403d), wherein said cells or portions are partially superimposed (404) like roof tiles for direct contacting, namely in the form called shingled. In particular, there is provided to print ECA on said cells or portions (403) and immediately pre-arrange them in a progressively superimposed way by forming shingled strings (402) in turn alternated in the direction of the head, with a particular operative logic (11.1 11.6) and with a particular automatic shingling apparatus (20) (FIGS. 5a-5b, 9a-9b), wherein said shingled strings (402) are pre-arrange and ready to be immediately loaded and pre-fixed (R3) on a backsheet provided with an encapsulating layer (401) (11.7 11.9), operating in the same workstation (S2) in a continuous cycle and without intermediate drying of the conductive adhesive.

[0083] Said pre-arrangement of shingled strings (11.1 11.6) and said loading with pre-fixing (11.7 11.9) occur simultaneously in a workstation (S2), wherein the automatic shingling apparatus (20, R1-R2, V1-V2) is integrated with the loading and pre-fixing apparatus (R3, V3) thanks to an innovative tray machine made up of a pneumatic shuttle-tray (210) with bi-directional translation, coordinated to a particular handler (R2). Said station (S2), being in its turn integrated in a production plant (30) sequentially made up of at least six workstations (S1-S6), wherein the entire photovoltaic panel (400), ready to be conveyed to end rolling, is assembled by progressive stratification, on a panel carrier tray (300) in transit. Said automatic station (S2), of the type combined in the means and in the functions, and bivalent in the use for assembling, if necessary, cells without superimposition, as it is described in detail in the following.

[0084] The proposed invention (10, 11, 20, 30, S2) provides that the assembly of the photovoltaic panel with superimposed cells, that is shingled, is made simultaneously, without the conventional separate formation of the strings with intermediate drying of the ECA, but integrating, in a single macro-phase of assembly (11) and in a single automatic workstation (S2), the entire construction of the panel (400) in its main structure (401, 402, 403), leaving to the following stations only the inter-string contacting or bussing (S3) and the front stratifications (S4, S5). In principle, this invention allows to simultaneously perform the assembly from the cell portion to the panel, according to an integration logic of the type called Cell-to-Module in English language, which is already known for photovoltaic panels with back-contact cells, but is not known for the modern panels where the traditional top-bottom contact cells are advantageously connected in shingled form.

[0085] Furthermore, it is proposed a method (10, 11) and an automatic apparatus (20, R3, S2) that are versatile in use, namely bivalent, in such a way as to obtain, also for said panels with traditional shingled cells, the well-known advantages reached by the modern methods and manufacturing plants of automatic type for panels with back-contact cells, as in the known prior art. The invention is therefore suitable for both architectures of photovoltaic panels, where the present description is particularly destined to the pre-arrangement and loading of strings made up of portions of traditional cells that are top-bottom connected in said shingled form, on a backsheet already provided with a lower encapsulating layer for the purpose of insulation and pre-fixing; in case, instead, of a back-contact panel, there is provided the use of a particular conductive and multi-layer backsheet such as, by way of example, in the aforementioned solutions EP2917942 (Baccini et al.), EP3090449 (Baccini et al.) or ITTV2017A084020 (Baccini et al.).

[0086] The proposed solution is easily implementable in a production line of the modular and highly automated type, made up of a total number of workstations selected according to the desired production capacity of the line itself, wherein some stations intended for particular assembly phases or sub-phases may be multiplied and/or adjacent and/or opposed one another according to specific project requirements; by way of non-exhaustive example, consider a possible doubling of the automatic apparatus that individually pre-arranges said alternated shingled strings (402) starting from cell portions (403), forming them complete and ready to be loaded one adjacent another on the backsheet, wherein said doubling may provide multiple adjacent lines or symmetrically placed relative to the panel-carrier tray in transit, one opposite to the other, that is one at each side, with synchronization of the loading of adjacent strings and with alternated heads for the purpose of bussing operations, as well as to avoid the downtimes of production. In this way, it is possible to halve the general assembly times concerning said combined and bivalent station. Therefore, by way of non-exhaustive example, in the following description of the invention (10-11, S2) (FIGS. 2-9b), firstly reference is done to a basic embodiment with a single loading line and a single shuttle-tray (FIGS. 4b, 5a, 5b) and then to a preferred high-productivity embodiment with a single printer, but with a double line for initial loading and two shuttle-trays (FIGS. 9a, 9b) that translate parallel and in a coordinated way each other at the sides of said printer.

[0087] More in detail, the proposed method (10) provides a particular macro-phase (11) of assembly of said cells on the backsheet (FIGS. 2, 3), wherein the positioning or lay-up of the cells occurs by pre-arranging them first (11.1 11.6) by shingled strings (402), preferably alternated in the direction of construction (211a-211b, FIGS. 8a-8b), starting from entire cells or equivalent cell portions (403), progressively superimposed one another (11.6, R2) immediately after the printing (11.4, 205), on a shuttle-tray (210) that translates back and forth, that is with a bi-directional logic (211, 211a-211b). Preferably, slices of cells pre-cut in equal parts are simultaneously printed, laying on the upward-facing contacts a predefined quantity of ECA (207) by means of a printer (205-207) in a continuous production line, using a technology of the silkscreen printing type or screen-printing, or volumetric dispensing, or jet-dispensing, or other equivalent technology. The progressive superimposition of said portions, one by one, it is carried out by means of a particular handler (R2) with chocked vacuum (214-216) depending on the number of portions (403a-403d) to pick up and release, as described in detail in the following (FIGS. 6-7).

[0088] At the beginning of the process of forming of the shingled string (11, 20), in said combined station (S2) or lay-up station, said cell slices or portions (403a-403d) are supplied in their own loading path (201) inside containers (203) that are shaped like boxes (FIGS. 5b, 6), which hold them tidily and repetitively stacked, one next to the other, with interposed spacers (217), in such a way as they can therein be picked up in a predefined groups by a first, even multi-line, handler of the robot type (R1a) or Cartesian portal (R1b), equipped with an end member of the pneumatic gripping hand type, like a perforated plate with vacuum in adhesion or a gripper with suction cups. By way of non-limiting example, in the preferential embodiment of the invention, it is foreseen that each portion is equal to a fourth of a standardized square cell, with sides equal to 156 mm, wherein said container (203) will be opportunely configured so as to carry said four portions on a single level, which are spaced apart, but together equivalent to an entire cell (FIG. 6), in such a way as to be able to be picked up all together (FIGS. 5a And 9a) from the special gripping hand of said first handler (R1a-Rb).

[0089] Such a solution ensures a high versatility of use; in particular, when changing the configuration of the supplied portions (403), for example their dimension or geometry, it is foreseen that only the corresponding container (203) and the end gripping devices of the three handlers (R1a-R1b, R2, R3) of the station (S2) shall be changed or adapted, which are interchangeable on the wrist for the above-mentioned purposes, in addition to the obvious changings to the handling program or software and to the printing screen of the ECA adhesive (205, 207). To this end, it is observed that the gripping hand of the first handler preferably consists of a plate machined with vacuum means obtained inside and which are placed according to said number of cell portions to pick up simultaneously; by way of example, a number of four slices is provided if in fourth of cell or a number of six slices if in sixth of cell, and so forth. The second handling (R2), instead, provides a particular gripping end member with chocked vacuum with independent sectors (214, FIG. 7), corresponding to each cell portion to be progressively positioned with a partial superimposition.

[0090] In said combined workstation (S2), the macro-phase of lay-up (11) is carried out by means of an automatic shingling apparatus (20) that prints and immediately places said equivalent cell portions (403a-403d) one onto the other like roof tiles, in such a way so as to pre-arrange shingled strings that are alternated also in the direction of construction (210-211), wherein the first laid portion or head is alternatively directed, at the moment of picking (R3), towards the end of the stroke or is even alternated in the polarity once the string is loaded on the backsheet, one next to the other, to facilitate the following phase of bussing. In said apparatus (20), said portions (403a-403d) are supplied in specific containers (203) in a loading path with a conveyor belt of the single-line (201, FIGS. 5a-5b) or multi-line (201a-201b, FIGS. 9a-9b) type, wherein multiple containers (203) can be loaded in a row and wait for their turn of emptying in order to ensure autonomy to the workstation (S2) and therefore to the entire production plant (30). Every container (203) is therefore placed with precision on the loading path (201), at the beginning of the assembly (100), in a loading position (202) where said first handler (R1a, R1b) begins to pick up said cell slices, or the entire cell, in a single gripping operation.

[0091] The different operations provided by the invention are in turn assisted by multiple vision systems of the multi-camera type and/or optical inspection AOI, which are structurally and functionally integrated with the different equipment of the station (S2) according to the operative, management and control purposes provided. For the ease of description, such vision systems are grouped (V1, V2, V3) by macro-functions localised as follows: before the printing (V1, R1a-R1b, TC1-TC2), wherein at least the position and/or the alignment of the cell portions are detected depending on the printing screen, after the printing (V2) (R2, AOI1, TC3) to control at least the quality of the execution and the position and/or the alignments of each cell portion for the loading with progressive superimposition on the shuttle-tray, after the completion of the shingled string (V3) (R3, TC4-TC7) to control the alignments and fiducials for the final loading of the string on the backsheet.

[0092] More in operative detail (FIGS. 2, 3, 5a-5b, 9a-9b), when said box container (203) reaches the loading position (202), a first handler (R1a, R1b) picks up the equivalent cell portions (403) extracting them from the top (11.1), or a single entire cell, and arranges them in groups for a preliminary control in a position such that a component of a first vision system (V1) can control the actual orientation of the cell slices in order to then correctly position them on the belt for the printing, which for example is an optical inspection means AOI with illuminator or a scanner or a camera integrated in the same structure of the handler or close to it. The same vision system (V1) can also carry out a check on the integrity of said cell portions just extracted, or entire cell, which, in case of verified faults can be successively stored in a separate reject post (11.c). The software of the vision system (V1), therefore, gives instruction to said handler (R1a, R1b) to carry and load (11.2) in an oriented way the group of equivalent cell portions (403a-403d) on a loading belt equipped with vacuum (204) in such a way that they may transit in predefined and oriented way, without altering their relative position, till reaching the printer (205), where a special processing area (206), which is empty in correspondence of the belts, will lift contrary to the head with the printing screen (11.4); this solution, in the preferred case of a type-stencil screen for contact printing.

[0093] In the preferred embodiment, before the printing (205) there is also provided a control of the alignments (11.3) of the portions (403) just being loaded on said belt (204), which may be made by means of two cameras (TC1, TC2) positioned in a row one after the other, where the first one (TC1) detects the alignment of the single cell portion on a stationary reference point, while the second one (TC2) detects the alignment on the previous portion. Said first vision system (V1) can provide multiple detectors to control the positions and alignments of the single portions before and after the loading on the belt, if necessary re-configurable according to the precision guaranteed by the handler (R1a, R1b) and/or the possibility of auto-calibration of the printing screen, and the bivalent use of the station (S2); for example, in the alternative case of panels with entire back-contact cells, it is sufficient to activate a single camera (TC2) to control the alignment on the belt.

[0094] Once the ECA adhesive is printed (11.4) in the positions defined by the printing screen, the printing processing area (206) lowers and the transport belt equipped with vacuum (204) forwards the ensemble of said portions just printed up to an unloading position, that is picking up (208) by a second handler (R2), which picks up in a single grip said equivalent cell portions as they are. Said handler (R2) is a robot (FIG. 7) equipped with a particular interchangeable gripping tool (214) on the wrist (212, 213), which essentially comprises a plate machined with vacuum devices obtained in the plate itself and which are placed according to the number of portions that shall be picked up simultaneously. Particularly, for the purpose of the invention, it is foreseen that in said second handler (R2) the picking member (214) is advantageously subdivided into independent sectors (216), corresponding to each handled cell portion (403a-403d), which are individually supplied by chocked vacuum channels (215a-215d) as the vacuum circuit is sectioned by an independent pilot-operated valve in such a way that the single gripping and release sectors (216) may be operated at choice, for example with a single programmed sequence or all at once simultaneously. In the alternative case of assembly of back-contact cells, it is foreseen that they are entire and loaded on the backsheet with the ECA adhesive facing downwards, namely overturned, wherein said overturning may occur individually by means of said second handler or may possibly occur at the end, namely simultaneously to the loading on backsheet of an entire row of adjacent cells.

[0095] Said device with independent sectors (20, 214, R2) (FIG. 5b, 7, 9a) allows to release each cell portion (403a-403d) one by one, advantageously co-ordinating itself with the movement of the shuttle-tray (210), wherein the shingled string (402) is progressively formed, which translates back and forth (211a-211b) in a controlled way along a rectilinear axis (211) that is preferably parallel to said loading belt (204), corresponding to the longitudinal axis of the string under construction. It (210) acts as a mobile support, wherein the single portions (403) are progressively laid (11.6) one onto the other with a partial superimposition (404) at the ECA adhesive (207), in such a way as to pre-arrange complete single shingled strings (402) in a continuous cycle, which are ready for the immediate picking up and transport (R3) on the backsheet (401); therefore, they are in turn alternated in their orientation of the head, that is of the first stored cell portion (FIGS. 8a, 8b) depending on the construction direction on said shuttle-tray (210) translating back and forth, namely forward (211a) or backward (211b). It has been experimentally observed that this alternation makes the manufacturing process faster and considerably reduces downtimes due to idle translations. Moreover, it can facilitate the following phase of bussing (S3) between adjacent strings, simplifying the interconnection elements reported and/or reciprocating the polarity between the heads.

[0096] Prior to said coordinated and progressive release (11.6), the second handler (R2) places the group of printed portions, picked up from the belt at a control position (11.5) wherein a first detector (AOI1) of the second vision system (V2), preferably of the optical inspection type with illuminator, checks the quality of the printing of ECA carried out, while a second detector like a camera (TC3) checks, from the bottom to the top, the actual orientation of the individual cell portions in said gripping hand (214) of the robot (R2). Said second vision system (V2), therefore, can carry out the check on the integrity of said cell portions, or entire back-contact cell, which in case of confirmed deficiencies can be stored in a separate reject post (11.c).

[0097] After such acquisitions (V2), the vision software gives instruction to said second handler (R2) to carry and direct (212) said group of printed cell portions (403, 207) in the correct position of progressive superimposition, wherein the gripping hand (214) of the robot (R2) will release, according to a predefined sequence (11.6), a single portion at a time (403a, 403b, 403c, 403d) on said shuttle-tray (210) that translates in a way coordinated to it (R2), chocking the gripping with independent sectors (216) by means of selection valves of the corresponding channels vacuum (215a, 215b, 215c, 215d), in such a way as to easily and precisely carry out a predefined superimposition (404) of each single portion. After each loading, said shuttle-tray (210) executes a controlled movement in such a way that the following loading can be placed in the same position, with an identical movement (212) of the arm of the robot (R2, 214), and so until the completion of the string (402). In principle, said handler (R2) and said shuttle-tray (210-211) operate together like a plotter, i.e. a working or writing unit, wherein a first mobile means, or head, is moved along one or more axes and handles a tool and/or a product as regards a second mobile means, or support, which simultaneously translates or rotates in a way combined to it, that is synchronized in order to carry out complex operations on more axes, in a confined space; said working unit operating with the help of electronic optical vision systems and with a logic control unit.

[0098] After having reached the end-of-stoke stop (210, 211a) or anyway the correct unloading position, it is foreseen that the entire string (402) is picked up (11, 7) by a third handler (R3) of the picking bridge type (250, 251) made up of a Cartesian portal (250) with a gripping and pre-fixing device (251) corresponding to the entire string, to be immediately controlled and transferred on the backsheet (401) that transits on a panel-carrier tray (300) that crosses the entire assembly line (30); said gripping and pre-fixing device (251) is of the pneumatic type and firmly holds each single cell or portion of shingled cell (403). Simultaneously to said transfer, therefore, there is the visual inspection (V3, 11.8) of the alignments of said string and of possible cracks, as well as of the stationary references or fiducial points on the backsheet and/or tray. Said positioning of each string is immediately followed by a fast-thermal fixing on the encapsulating layer of the backsheet (401), also called pre-fixing (11.9), performed with localised heating according to prior art, as for example in EP3090449 (Baccini et al.).

[0099] At the service of said third handler (R3), there is therefore provided a third vision system (V3, TC4-TC7) that firstly detects, from the bottom, (TC4) the head-tail alignment of the shingled string just being formed and picked up, relative to the gripping device, by means of two acquisitions of beginning-end of the string, also called head-tail; then, a network of detectors is placed above the panel under assembly or above the backsheet (401), for example three pairs of cameras (TC5, TC6, TC7) placed along the broadsides, suitable to detect the stationary references of the product, called fiducials, like coordinates useful to said gripping and pre-fixing device (251) in order to correctly position the shingled strings (402) adjacent one another.

[0100] In a more detailed embodiment of said gripping and pre-fixing device (251), for the purpose of firmly holding each single cell or shingled cell portion (403a-403d), the same is preferably shaped like a perforated plate that acts in adhesion on the string, with vacuum activated only on the holes corresponding to each cell portion; as an alternative, an equivalent micro-pneumatic system with suction cups or gripper is suitable. Moreover, means for the localised heating are arranged, which are suitable for the immediate pre-fixing to the encapsulating layer of each cell portion that forms the shingled string, avoiding the conventional dry-curing of the ECA adhesive. Said pre-fixing means, alternatively, may be integrated in the holding plate or form a second device of the presser-heater type, with similar shape, that operates in the same Cartesian portal in a coordinated way to it.

[0101] The production sequence (FIGS. 2, 3) of a photovoltaic panel with shingled cells, therefore, according to the assembly method (10) proposed by the invention (FIG. 2), includes a first phase operative (101, 51) of positioning a backsheet with encapsulating layer (401) facing upwards on a panel-carrier tray (300) that horizontally passes through the different workstations (S1 S6) placed in a row, to return (301) then to a lower level (FIGS. 4a-4b), then a second innovative operative phase called macro-phase (11) of lay-up, wherein different operations called operative sub-phases (11.1-11.9, 11.c, 11.s) are integrated in a coordinated and simultaneous way, and which are described in detail in the following, therefore a third operative phase (103, S3) of bussing of said shingled strings of the previous macro-phase (11, S2), followed by a fourth operative phase (104, S4) of superimposition of the upper encapsulating layer and corresponding control, then a fifth operative phase (105, S5) of laying of the front glass, and finally a sixth operative phase (106, S6) of overturning the layered panel, for its delivery to the rolling furnace. In case of bivalent use of the station (S2), to assemble panels with back-contact cells, as an alternative to the above-mentioned superimposition phase (11.6, 404), it is foreseen that the entire printed cells are loaded (210, R2) and aligned without superimposition like a string of cells that are not electrically connected, and preferably top-bottom overturned by means of the same gripping means with vacuum (R3) suitable to transfer and load them with the contacts facing downwards, on a backsheet of conductive type; therefore, in the case of back-contact cells, the above-mentioned station of bussing (S3) remains unused.

[0102] With greater reference to the operative details of the proposed method, the pre-fixed aims are achieved by printing and immediately pre-arranging the cell portions (403a-403d) for shingled strings (402), alternated in the direction of construction, according to a macro-phase of lay-up (11; S2) including the following operative sub-phases (11.1-11.9, 11.c, 11.s) that are functionally integrated one another in such a way as to print and pre-arrange said shingled strings, load and pre-fix them on the backsheet in a continuous cycle (FIGS. 2,3), without intermediate drying or dry-curing: [0103] (11.1) first sub-phase of picking with a first robot (R1a-R1b), from a container (203, 217) like a box (FIG. 6), equivalent cell portions (403) corresponding to an entire cell cut into identical slices (403a, 403b, 403c, 403d), arranged in adjacent stacks and with the contacts upwardly facing, with control of the actual position in order to orient the following laying on a belt and with possible checks for cracks or other non-compliances; [0104] (11.2) second sub-phase of oriented loading of said equivalent cell portions on a loading belt (204) with pneumatic vacuum for holding them; [0105] (11.2) third sub-phase of visual inspection (V1) of the actual positioning with possible checks; [0106] (11.4) fourth sub-phase of silkscreen printing (205) of the ECA conductive adhesive (207) on the contacts of each equivalent cell portion; [0107] (11.5) fifth sub-phase of visual inspection (V2) of the quality of the ECA laying and possible re-positioning, that is correction of the orientation of the printing screen or stencil, with detection of the actual position, that is the alignments of each portion for the purpose of the following release, and possible checks; [0108] (11.6) sixth sub-phase of progressive superimposition like roof tiles, of said equivalent cell portions (403a, 403b, 403c, 403d) obtaining complete shingled strings (402) that are alternated in their head polarity, by means of a second robotic handler (R2) with chocked gripping hand (214-216) that arranges them one by one on a bi-directional shuttle-tray (210), translating back and forth along a rectilinear axis (211) corresponding to the axis of the string under construction and parallel to said loading axis (204). The direction of superimposition of said portions is in turn reciprocated, that is being the same until the completion of a string (402) along the forward path (211a) of said shuttle-tray (210), then returning (211b) with superposition in the opposite direction; [0109] (11.7) seventh sub-phase of picking said alternated shingled string with a gripping bridge at the end-of-stroke stop (211a) of said shuttle-tray (210), wherein a plate with activated vacuum on each portion of the shingled string translates on a Cartesian portal (250), picks it up entirely (402) to then orient it and translate it up to the backsheet, clearing said shuttle-tray for its return (211b). To create a string head with polarity opposite to the previous one, for the purpose of facilitating the contacting between adjacent strings, there is possibly provided to overturn of the entire string in an alternated way, namely every other string; [0110] (11.8) eighth sub-phase of control (V3) of the tail-head alignment of said shingled string, with possible checks. [0111] (11.9) ninth sub-phase of oriented loading or laying, and pre-fixing with localised heating of said shingled string (402) on the backsheet with the encapsulating layer (401) facing upwards, based on the position of stationary references or fiducial points (V3); [0112] (11.c) possible sub-phase of unloading the cracked and/or non-compliant equivalent cell portions, as an alternative to the second (11.2) or sixth (11.6) sub-phase; [0113] (11.s) possible sub-phase of unloading of the cracked and/or non-compliant strings, as an alternative to said ninth sub-phase (11.9).

[0114] Particularly, with respect to the known solutions for back-contact cells of documents EP2917942 (Baccini et al.), EP3090449 (Baccini et al.) or ITTV2017A084020 (Baccini et al.), the invention (10, 11, S2, S3) provides to print and pre-form complete strings (402) starting from cells or cell portions with top-bottom contact, which are superimposed in shingled form (402, 404) on the electrical contacts (207), in such a way as to immediately load them on a non-conductive backsheet in a continuous cycle and without separate operations, to industrially operate in the advantageous Cell-to-Module mode using traditional cells with top-bottom contact. Such a result is achieved with a progressive superimposition (210, 404, R2) of the portions of a cell just being printed, one by one, by means of an innovative tray apparatus made up of a shuttle-tray with bi-directional translation (210, 211) and coordinated in the movements to the handler (R2) that is able to move and rotate a special pneumatic gripping tool (212-216) suitable to individually release (215a-215d) each portion and operating in a coordinated way to said shuttle-tray (210) and to a dedicated vision system (V2, TC3), thus obtaining (11.1-11.6) shingled strings (402) already ready to be immediately transferred and fixed on a non-conductive backsheet (11, 7 11, 9).

[0115] It is observed that the application of a similar loading with pre-fixing is known only for the assembly of adjacent back-contact cells, wherein a handler of the Cartesian portal type picks them up and transfers them also applying localised heating for the purpose of fixing them on the encapsulating layer of a backsheet of the conductive type, which electrically interconnects them therein forming the strings of the panel. In the known solutions, in fact, there are no problems related with the simultaneous handling of cells already electrically contacted and specifically arranged, without dry-curing. This invention (11, S2) provides to transfer non-conductive complete strings of the shingled type (402) on a backsheet, which are pre-formed with single portions of cell (403) and electrically contacted for top-bottom superimposition (11.6) at the contacts (207, 404), wherein the ECA is printed (11.4); therefore, said shingled strings are pre-arranged and interconnected prior to their transfer on the backsheet, which is provided with the encapsulating layer only and not necessarily with a conductive layer, therefore it is essential to handle and load them without no relative translation between the cell portions, and particularly at the ECA adhesive on the electrical contacts on the ECA, thus avoiding the conventional operations of intermediate drying or dry-curing provided for shingled strings. To this end, a handler (R3) is provided, which is able to pick and correctly orient the entire string by applying vacuum on each cell portion (403a-403d), in order not to alter the contacting and the corresponding alignments, which is also combined to an integrated vision system (V3) that, prior to the loading, checks the actual alignment of the string with tail-head acquisitions on a stationary reference point (TC4), preferably from the bottom to the top, and then checks from the top (TC5-TC7) the actual positioning relative to a network of stationary references, like fiducial points or fiducials, on the tray and/or on the backsheet.

[0116] In this way, it is possible to perform, in a continuous back and forth cycle (210-211), complete and already electrically contacted strings, also alternated in the direction of the head of the string, that is the first portion laid according to the direction of construction, namely of translation of said shuttle-tray, thus considerably reducing time and industrial costs for production. In particular, the proposed solution (10, 11) is feasible in a single workstation (S2) of the compact and integrated type, which is automatic in the operation and combined in the functions, wherein said printing, said pre-arrangement of shingled strings and said loading on a backsheet are carried out simultaneously and without dry-curing. Moreover, it shall be noticed that the proposed solution (10, 11) allows a bivalent use of the equipment, wherein said combined station (S2) of lay-up is particularly suitable for assembling, in an innovative and advantageous way, the aforementioned shingled strings (402) on a non-conductive backsheet, but also allows to transfer adjacent back-contact cells on a conductive backsheet according to a substantially known technique, with an extreme versatility of use and saving investments as it is nowadays required to the manufacturers of photovoltaic panels.

[0117] The production plant (30) (FIGS. 4a, 4b) suitable to carry out the proposed solution is made up of automatic workstations (S1-S6) placed in a continuous line, wherein, compared to the aforementioned known solutions, it is foreseen that said second station (S2) of lay-up performs a substantially different sequence of operations for the purpose of said pre-arrangement in a continuous cycle (11.1-11.6, 20) of shingled strings (402) starting from said portions (403a-403d) of traditional cell, and load them immediately (11.7-11.9, R3) on a non-conductive backsheet without relative translations and without dry-curing, as set forth above. Moreover, a following third station (S3) of simplified bussing of said shingled strings (402) is introduced, which is obviously not used in said alternative case of assembly of back-contact cell panels. Furthermore, at the beginning of the plant, a possible preparatory station (Sp) is provided in order to convey non-standard formats of photovoltaic panel.

[0118] More in detail of the provided equipment, it is proposed an advantageous combined and bivalent station (S2) for panels with alternated shingled strings (402) or also back-contact panels with adjacent cells, which comprises a particular automatic shingling apparatus (20) made up of means (201 216, R1-R2, V1-V2) coordinated one another in such a way as to pre-form strings starting from a single cell or equivalent cell portions (403), which operate in a functional combination also with the automatic means of loading and pre-fixing (R,; V3) on the backsheet of said pre-formed strings, like an automated operative, compact and multifunction unit, wherein said pre-arrangement function of the shingled string (20) and that of its positioning on the backsheet (R3) interface at the end-of-stroke stop of said shuttle-tray (210), according to an integrated logic of assembly, called cell-to-module, that is applied to panels with strings formed by superimposed or shingled cell portions (404). To this end, said shingling apparatus (20) is integrated and coordinated with all the other means of the operative station (S2) of lay-up (FIGS. 5a, 9a, 9b), including the multiple vision systems (V1-V3) and the electronic means for the management and control of the station (S2) and of the entire plant (30).

[0119] In the basic embodiment illustrated in the figures (FIGS. 5a and 5b), a single loading path (201) of equivalent cell portions (403) and a single shuttle-tray (210) are provided, wherein said shingled string (402) is pre-formed; in that case, the first handler, intended to load said cell portions from the box containers, is advantageously an articulated arm robot (R1a) coordinated to a first vision system (V1). The second handler (R2) is a robot with a particular gripping tool (214) provided with chocked vacuum (215a-215d), which is coordinated to the movement of said shuttle-tray (210) and to a second vision system (V2). The third handler (R3) is a Cartesian portal (250, 251) coordinated to a third vision system (V3), comprising a multifunction gripping and pre-fixing means (251) that translates from the end-of-stroke stop closer to said shuttle-tray (210) up to the backsheet; such means (251) is of the pneumatic plate type and suitable to pick up and translate an entire pre-formed shingled string (402) without relative movements among the pieces (207, 402, 404), acting with the vacuum on each cell or cell portion (403), and is simultaneously joined and/or combined with heating means that introduce localised heat on each cell or cell portion, for the purpose of a punctual pre-fixing on the encapsulating material of the backsheet.

[0120] The gripping and pre-fixing means (251) can be split apart, wherein the gripping means and the pre-fixing means are separated when operating, but coordinated in their action, being of similar shape and translating on the same Cartesian portal; such a case is schematically illustrated by way of example in said basic embodiment (FIGS. 5a, 5b), wherein a first element with a perforated pneumatic plate or gripper or equipped with micro suction cups is provided, which picks up and places each string on the backsheet in such a way that a second pre-fixing element immediately supplies localised heat on each cell portion, avoiding any relative movement among the portions. Alternatively, for special production and/or plant requirements, it is possible to provide an equivalent handling system, wherein the gripping and pre-fixing means are integrated in a single multi-function element, such as for example a versatile, smooth contact plate with vacuum holes selectively activated on each cell portion of the shingled string, in order to grip without relative translations, and with heating means inside it for an immediate pre-fixing simultaneously to the laying. Such a case is schematically represented, by way of example, in the preferred high-productivity embodiment (FIGS. 9a, 9b) where it (251) is illustrated as dashed in the picking position, while it is represented with a continuous line in the final pre-fixing position on the backsheet.

[0121] Therefore, the following means are provided starting from the beginning (100) of said macro-phase (11): [0122] at least one loading path (201) for the boxes (203), with spacers (217), which contain the equivalent stacked cell portions (403); [0123] a first handler of the robot type (R1a) (FIG. 5a, 5b) or a Cartesian portal (R1b) (FIG. 9a, 9b) with gripping means with pneumatic plate, interposed between said loading path (201) and a loading belt (204) leading to the printer, for picking and loading said equivalent cell portions; [0124] at least one loading belt (204) provided with vacuum, on which the equivalent cell portions picked up (R1) from the box are placed, serving as a controlled extension of said loading path, which holds them translating the same first in the correct position for the printing (205, 206) and then in the picking position (208, R2); [0125] at least one flat silkscreen printer (205), crossed by said belt (204) with vacuum, comprising a processing area (206) wherein the laying of ECA (207) on said equivalent cell portions is performed; [0126] a second robot handler (R2) (FIG. 7) equipped with a particular orientable gripping hand (214), with independent sectors (216) and chocked vacuum channels (215), which is interposed between said position of picking (208) from the belt and the position of loading (209) on a shuttle-tray (210) that is coordinated to it, in order to load the equivalent cell portions just printed and position them, one by one, in a progressively superimposed way (404) on ECA (207) by independently releasing each portion, with translation and orientation of the arm (212) in such a way that it is also coordinated to the progression of the shuttle-tray (210), wherein said progressive loading occurs in a continuous cycle in both directions of translation with the superimposition (404) in turn directed in the opposed direction in order to obtain a shingled string with alternated orientation of the head, that is the first laid cell in adhesion on the plane (FIGS. 8a, 8b); [0127] at least one shuttle-tray (210) supporting and holding the string under construction, which translates back and forth in a bi-directional way (211a-211b) on a rectilinear axis corresponding to the longitudinal axis of the string and which is parallel to said loading belt (204), with an end-of-stroke stop in the coordinated position of picking (R3) of the shingled string; [0128] a third handler (R3) of the gripping bridge type with vacuum, namely a pneumatic plate (251) that translates on a Cartesian portal (250), assisted by a multi-point vision system (V3), external to the equipment (20), but integrated in the same station (S2).

[0129] Moreover, the following vision systems are provided: [0130] a first vision system (V1) with automated optical inspection or AOI, at said first robot (R1a, R1b), in order to control the actual position of the equivalent cell portions before the laying (11.2) on the belt (204), so as to orient the loading, and after it to check the actual alignments (11.3) for the purpose of the printing and check for cracks and/or non-compliances; [0131] a second vision system (V2) with automated optical inspection or AOI, at the said second robot (R2), to check for the actual laying of printed ECA (11.5) and to assist in the progressive superimposition (11.6) of the cell portions when forming the shingled strings (402) on the shuttle-tray (210); [0132] a third vision system (V3) with automated optical inspection or AOI, at the third handler (R3) to check for the actual alignment of the shingled string being picked up (11.8) and therefore load it correctly on the backsheet relative to the stationary points (11.9).

[0133] In the preferred high-productivity embodiment of the invention (11, S2), being of the multi-line type (FIGS. 9a, 9b), two loading paths (201a-201b) of the boxes (203) are provide, which are coupled to a first handler (R1b) of the Cartesian portal type in such a way that the pneumatic gripping means moves transversely, with rapidity and precision, on both lines; in particular, there is provided the use of at least two identical bidirectional shuttle-trays (210a, 210b), which are placed parallel to the sides of said printer (205), namely one at each opposite side relative to it, which translate back and forth (211a, 211b) in a coordinated way with respect to each other and coordinated with respect to said handler (R2, R3) to operate continuously without working downtime, also in the mode that is technically called in background operation to the machine. In this way, for example, while a first shuttle-tray (210a) is at the end-of-stroke stop near the third handler (R3) in such a way to be able to pick up and load the shingled string just being formed (402) on the backsheet (401), a new shingled string is simultaneously under formation on the other shuttle-tray (210b) by means of the second handler (R2).

[0134] With reference also to the figures (FIGS. 9a, 9b), in the preferred embodiment, it is provided a first vision system (V1, TC1-TC2) near said first handler (R1b), in order to control the actual positioning of the cells for the purpose of the printing, which includes two detection points (TC1, TC2) between the loading and the printer, wherein a first point (TC1) provides the position of the first of said equivalent cell portions (403a-403d) relative to a stationary reference, while the second point (TC2) allows the alignment of the second of said portions on the first. It is observed that in the case of entire MWT cells, the alignment occurs using only one detection point (TC2). It is thus apparent that said first vision system (V1) may include a higher or lower number of detection points depending on the particular technology adopted to handle said containers, and/or to load the cells or cell portions on the pneumatic belt, and/or to calibrate the printing screen.

[0135] There is then (FIGS. 9a, 9b) a second vision system (V2, AOI1-TC3) placed after the printer (205) and near the second handler (R2), wherein, in a first detection point (AOI1), two acquisitions of the cell portion just being printed are executed for the purpose of controlling the quality and the alignment of the printing, possibly with a consequent calibration of the printer or the reject of non-compliant products, while in a second point (TC3) the alignment of the cell or cell portion relative to the gripping hand of the robot is detected from the bottom for the correct alignment of the same on the shuttle-tray that acts as a tray machine.

[0136] Finally, there is (FIGS. 9a, 9b) a third vision system (V3, TC4-TC7) assisting the third handler (R3), where firstly the alignment of the shingled string just being printed relative to the gripping device is detected from the bottom (TC4), by means of two acquisitions of beginning-end of the string, while a network of cameras is placed above the panel being assembled, for example three pairs (TC5, TC6, TC7) placed along the broadsides and suitable to detect the stationary references of the product called fiducials, like coordinates that are useful to said gripping device of the handler (R3) suitable to correctly position each string on the backsheet.

REFERENCE

[0137] (10) automatic assembly method for a photovoltaic panel with traditional superimposed or shingled cells, according to this invention; [0138] (100) start; [0139] (101) operative phase of horizontal positioning of a backsheet with an encapsulating layer on a clear panel-holder tray, (103) operative phase of bussing the alternated shingled strings, (104) operative phase of superimposition of the upper encapsulating layer, (105) operative phase of laying of the front glass, (106) operative phase of overturning the layered panel; [0140] (11) macro-phase of lay-up, with printing, pre-arrangement, loading and pre-fixing of complete and alternated shingled strings, according to this invention, with an integrated assembly logic of the Cell-To-Module type. Said macro-phase consists of operative sub-phases (11.1-11.9, 11.c, 11.s) functionally combined one another and integrated in such a way as to pre-arrange and directly load, in a continuous cycle and without intermediate drying, complete shingled strings that are alternated in the head direction, for the purpose of the following connection between strings or bussing; [0141] (20) automatic shingling apparatus, object of this invention, for printing ECA and pre-arrange shingled strings with cells or cell portions of the traditional type, with top-bottom contacts, connected with a partial superimposition in shingled form, ready to be loaded and pre-arranged without intermediate drying on a backsheet with encapsulating layer. [0142] (201) loading path of the boxes; [0143] (202) loading position of cells or cell portions; [0144] (203) boxes or containers with stacked cells, which are entire or equivalent cell portions that are stacked and adjacent one another with interposed spacers; [0145] (204) loading belt with vacuum; [0146] (205) flat silkscreen printer of ECA; [0147] (206) printing processing area of the equivalent cell portions; [0148] (207) conductive adhesive, of the ECA type at the electrical contacts; [0149] (208) picking position of the printed cells; [0150] (209) loading position, on the shuttle-tray; [0151] (210) shuttle-tray supporting and holding the shingled string under construction, of the bi-directional back-and-forth translation type on a rectilinear axis; [0152] (211) rectilinear axis of horizontal movement, back and forth (211a-211b); [0153] (212) wrist of the robot, with controlled movement in vertical and horizontal direction and rotation; [0154] (213) fixing plate; [0155] (214) end handling member of the pneumatic type, with chocked vacuum with independent sectors; [0156] (215) chocked vacuum channels (215a-215d), controlled independently to sequentially release the cell portions, one by one (403a-403d), in combination to the translation of the shuttle-tray; [0157] (216) independent sector, for the purpose of the release; [0158] (217) spacers; [0159] (250) Cartesian portal of the type with frame structure, which supports longitudinal and transverse axes of handling wherein at least one gripping and pre-fixing device slides; [0160] (251) gripping and pre-fixing device, comprising pneumatic gripping means to pick up and translate an entire shingled string just being formed, for example of the perforated plate type with selective vacuum in adhesion or gripper or micro suction cups, with also means for the localised heating for the purpose of an immediate pre-fixing of each cell portion that forms the shingled string to the encapsulating layer, avoiding the conventional dry-curing of the ECA adhesive. Said pre-fixing means can, alternatively, be integrated to said gripping device or form a second device, like a presser-heater of shape similar to the first one and suitable to operate in the same Cartesian portal in a coordinated way to it; [0161] (30) automatic assembly plant for a photovoltaic panel, according to this invention, made up of multiple workstations (S1-S6, Sp) aligned in a consequential way and crossed by a panel-holder tray, wherein particularly the second station (S2) is an innovative combined and bivalent station to carry out the proposed assembly method; [0162] (300) panel-holder tray; [0163] (301) empty return tray, recirculating at the lower level; [0164] (400) panel; [0165] (401) backsheet with encapsulating layer; [0166] (402) alternated shingled string, according to this invention, namely a string made with cells or cell portions that are partially superimposed on the contacts like roof tiles, being complete and ready to be loaded and pre-fixed on the backsheet without intermediate drying, and in turn alternated in the direction of the superimposition. The shingled string, in fact, exhibits the head at the end of the stroke, namely the first cell is laid in a full adhesion and in turn placed in the opposite direction as the shuttle-tray translates back and forth by progressively forming each string both during the forward and backward movement, without working downtime. [0167] (403) equivalent cell portions, that is photovoltaic cell portions that are identical one another, corresponding to an entire cell divided in equal pieces like slices, for example in the number of four portions (403a-403d), each one corresponding to a fourth of a standard cell having sides that are equal to 156 mm in the figures of this invention, or any other subdivision in equal pieces; [0168] (404) area of superimposition between cells or cell portions, on the conductive adhesive just being printed; [0169] (R1, R1a-R1b) first handler, with pneumatic gripping hand as a plate machined with vacuum devices obtained in the plate itself and placed according to the number of slices that shall be picked up simultaneously, for example four slices if in fourth of cell or six slices if in sixth of cell. Such a handler is preferably of the robot type (R1a) in the case of a single loading path and a single shuttle-tray, or a Cartesian portal (R1b) rapidly serving multiple lines that are parallel one another; [0170] (R2) second handler, coordinated to the movement of the shuttle-tray, of the robot type with pneumatic gripping hand with independent sectors and chocked vacuum to progressively release each cell portion one onto the other, with a partial superimposition; [0171] (R3) third handler, of the Cartesian portal type, wherein a pneumatic gripping tool corresponding to the entire string translates, such as for example a plate provided with vacuum holes that can be activated on each cell portion of the string, or a gripper plate or with micro suction cups, also including heating means suitable for the localised pre-fixing on the encapsulating layer. Said plate and said heating means are preferably integrated in a single monolithic element or may be two elements coordinated one another and engaged on the same Cartesian portal in order to act on the same shingled string, one immediately after the other, avoiding any relative translation between the single cell portions. [0172] (S1-S6, Sp) workstations of the automatic assembly plant (30), according to this invention; the first station (S1) is for the positioning of a backsheet with an encapsulating layer on a panel-holder tray, the second station is an innovative combined station (S2) of lay-up for strings shingled with superimposed cells, and it is bivalent in the use in order to load adjacent back-contact cells, the third station (S3) is for the bussing of the shingled strings and therefore is not used in case of back-contact cells, the fourth station (S4) is for the superimposition of the upper encapsulating layer, the fifth station (S5) is for the superimposition of the front glass, the sixth station (S6) is for the overturning of the panel for the end rolling. In the case of panels with non-standard formats, at the beginning a preparatory station (Sp) is possibly pre-arranged; [0173] (V1, V2; V3) first, second and third vision system, of the multi-function and integrated type, with multiple control cameras (TC) and/or automated optical inspection means (AOI), being respectively: in correspondence of the first handler (R1a-R1b, TC1-TC2; V1) and before the printer to allow for an oriented loading of the cells or cell portions for the purpose of the printing; then in correspondence of the second handler and after the printer (R2, AOI1, TC3, V2), to control the quality of the printing and successively the exact position of the contacting points relative to the edge of the cell; finally, in correspondence of the third handler (R3), before the loading on the backsheet to detect the alignment of the shingled string on the shuttle-tray by means of two acquisitions (TC4), on the first and the last cell, with also a network of cameras above the backsheet (TC5, TC6, TC7) that allows the exact positioning and final pre-fixing of each string relative to the stationary reference points.