Solar cell unit, solar cell array, solar cell module and manufacturing method thereof

A solar cell unit, comprising:

• a first cell including a first cell substrate and a plurality of first secondary grid lines disposed in parallel on a front surface of the first cell substrate;
• a second cell adjacent to the first cell, the second cell comprising a second cell substrate and a plurality of second secondary grid lines disposed in parallel on a back surface of the second cell substrate;
• a conductive wire intersecting and weldingly connected with the plurality of first secondary grid lines by a welding layer, where:
• the welding layer is disposed on at least a portion of the conductive wire around an entire circumference of the at least portion of the conductive wire,
• the plurality of first secondary grid lines have a width in a welding position with the conductive wire greater than a width thereof in a non-welding position, and the plurality of first secondary grid lines have a height in a welding position with the conductive wire greater than a height thereof in a non-welding position, thereby stabilizing connections with the conductive wire and enhancing peel strength of the conductive wire;
• wherein the conductive wire comprises a metal wire, and the metal wire extends reciprocally between the front surface of the first cell and the back surface of the second cell;
• and
• wherein the first secondary grid lines comprise a middle secondary grid line disposed at a middle portion of the first cell and an edge secondary grid line disposed adjacent to an edge of the first cell,
• a width of the edge secondary grid line is larger than a width of the middle secondary grid lines, and the edge secondary grid line comprising a plurality of welding positions and a plurality of non-welding positions,
• wherein each welding position of the edge secondary grid line has a length longer than a length of each non-welding position between adjacent welding positions of the edge secondary grid line, wherein the length of each welding position of the edge secondary grid line is parallel along a longitudinal direction of the first secondary grid lines and the length of the non-welding position of the edge secondary grid line is parallel along the longitudinal direction of the first the secondary grid lines.