NOVELTY - Forming photovoltaic cell from common layer (preferably conductive layer) on substrate, involves making a first pass with first laser beam on an area of common layer, to form a groove (606) and two edges (6081, 6082) separated by the groove in the common layer, where the groove provides first level of electrical isolation between the two edges; and making a second pass with second laser beam on the same area of common layer, to provide a second level of electrical isolation between the two edges. The second level of electrical isolation is greater than first level of electrical isolation.    USE - For forming a photovoltaic cell from a common layer (e.g. conductive layer) on a substrate; useful in fabrication of solar cell unit (claimed) and in microchip fabrication; useful for segmenting solar cells into individual photovoltaic cells, to generate high output voltage through integration of segmented photovoltaic cells.    ADVANTAGE - The method creates electrically isolating grooves, thus eliminating voltage reduction caused by low-resistance shunts across the grooves. The method provides appropriate optical energy to an area that is already affected by previous optical exposure, to remove residual material. Thus, the method constructs solar cells by reducing or eliminating presence of shunts in solar cells. The solar cells can have cylindrical or planar shapes. The method can be used to facilitate a broad array of micromachining techniques including microchip fabrication. The method provides monolithic integration which reduces current carrying requirements of the solar cell, thus reducing electrode, transparent conductor and counter-electrode current carrying requirements, and minimizing the material costs. Thus, the method forms electrically-isolating grooves that are needed to form serially connected photovoltaic units in the solar cell, in an improved manner.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a method of separating a first portion (602A) from a second portion (602B) of a first layer in a solid volume (600) including the first layer and a second layer (604) made from different substances, involving making a first pass with a first laser beam over an area of the solid volume; where the first pass removes all of the first layer in the area, to create a channel with two edges in the first layer, and to form a first portion of the first layer bounded by the first edge and a second portion of the first layer bounded by the second edge, such that the intersection of the first edge and the first layer is defined by a first lip and the intersection of the second edge and the first layer is defined by a second lip, and to create a heat-affected zone in a first area bounded between the first lip and the second lip; and making a second pass with a second laser beam over the first area, to remove a portion of the heat-affected zone; and    (2) a solar cell unit comprising a substrate; and several solar cells linearly arranged on the substrate, with each solar cell containing several layers including a lower back-electrode layer, a semiconductor junction layer and an upper transparent conductor layer; where the transparent conductor layer of the first solar cell is in serial electrical communication with the back-electrode layer of the second solar cell, and the first layer or common layer selected from the back-electrode layer, the semiconductor junction layer or the transparent conductor layer is patterned by the method, which involves making the first and second pass with first and second laser beams to form electrically isolating grooves.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of a fabrication step of a photovoltaic cell.    Solid volume (600)    First layer portions of solid volume (602A, 602B)    Second layer of solid volume (604)    Groove (606)    Edges. (6081,6082)