Plant for the automatic assembly of photovoltaic panels with solar cells of the H-type, with front-back connection of the cells carried out at low temperature, comprising workstations which progressively assemble the panel within a tray, requiring the previous loading of a supporting backsheet with a layer of encapsulating material, said stations being of the type crossed by a continuous conveying line with recirculation of trays, said plant being characterised in that said workstations are modular elements shaped as right-angled parallelepipeds sequentially arranged in a linear series (100A-I); said stations (100A-I), being adjacent in correspondence of at least one side opening of each station (100A-I) in such a way as to be horizontally crossed by said conveying line of the trays both at the level of the working surface and at the level of the recirculation, which is parallel and underlying with respect to it; said workstations (100A-I) comprising automatic conveying and working means of the type with Cartesian robot, with a structure with mobile gantry for roto-translation (118a-d) on power-operated rails and at least one mobile head (103,119a-b); and wherein each mobile gantry is constrained to said power-operated rails in such a way as to enable the horizontal translation and also the rotation (11 8d) around the vertical axis, facilitating the automatic alignments; said mobile head, being power-operated at least to translate horizontally along the longitudinal axis of the mobile gantry and also to operate vertically; said mobile head comprising means for the pneumatic loading and/or means for the measured and calibrated dispensing of material intended for electrical contacting and/or means for pre-fixing by localised heating, in such a way as to enable the horizontal assembly of all the components by progressive superimpositions on said backsheet (309, 310) loaded on the tray with the encapsulating material facing upwards, to form a panel ready for rolling; said plant comprising from upstream to downstream the following workstations: a first station of loading on the tray of said backsheet with the encapsulating material, a second station of application of the cross ribbons, with ECA and pre-fixing, a third station of application of the first row of interconnecting ribbons, with ECA and pre-fixing, a fourth station of laying in rows of the cells and of the related interconnecting ribbons, in alternated and repeated series, with ECA and pre-fixing, an optional fifth station twin of the previous station in such a way as to complete the cover in a rapid and complementary way, a sixth station of laying of the front encapsulating material, a seventh station of laying of the front glass, an eighth station of overturn and outcoming of the compliant panel, a ninth station of recirculation of the tray made empty, if the panel is compliant, or of deviation, if the panel is non-compliant; at least said stations (100A-G) comprising automatic control devices for checking the single working processes performed and for the calibration of the movements, being of the type with cameras and vision software electronically integrated with the logic control unit of the plant; said plant being managed by a programmable logic control unit, which supervises the whole plant in an integrated way.