A method of performing screen printing on a substrate used for the manufacture of a solar cell is provided. The method includes moving a print head over a screen by a first drive actuator to perform a printing stroke in a first direction. The method includes moving a material processing head in the first direction by a second drive actuator to perform a material processing stroke behind the print head. The print head is moved away from the material processing head by the first drive actuator during a distance increasing phase of the printing stroke to increase a separation distance between the print head and the material processing head.

A printing screen unit comprising a mesh printing screen and a supporting frame which is attached to the printing screen, wherein the printing screen comprises a first, outer mesh which is attached to sides of the supporting frame and includes an aperture therein, and a second, inner mesh which is attached to the outer mesh, wherein threads, providing warp and weft, of the outer mesh are aligned so as to be substantially orthogonal to the sides of the supporting frame, wherein threads, providing warp and weft, of the inner mesh being aligned so as to have acute angles of between 0 degrees and 45 degrees to the respective sides of the supporting frame, wherein the printing screen is tensioned by an external tensioning assembly to a first tension when the printing screen is attached to the supporting frame, and the sides of the supporting frame are displaceable such that the sides of the supporting frame are displaced on release of the first tension by the external tensioning assembly, and the printing screen has a second, residual tension lower than the first tension.

A method (500) for printing on a substrate (102) for the production of a solar cell, the method comprising: printing (501) a wet pattern on the substrate (102); extracting (503) three-dimensional morphological data of the wet pattern (104) in real-time using an in-line profilometer (101); wherein the printing of the wet pattern on the substrate is controlled in real time at least in part based on previous three-dimensional morphological data obtained by extracting the three-dimensional morphological data.