Thin-film solar cell

A thin-film solar cell, comprising:

• an insulating substrate;
• and
• a plurality of unit solar cells formed on the insulating substrate, each of the plurality of unit solar cells including:
• a photoelectric conversion portion including a first electrode layer, a photoelectric conversion layer, and a second transparent electrode layer, sequentially formed on a front surface of the insulating substrate, and
• a rear electrode layer formed on a rear surface of the insulating substrate, the rear electrode layer being electrically connected to the second electrode layer via a plurality of current collection holes passing through the insulating substrate,
• wherein a portion of the first electrode layer of one of two adjacent unit solar cells, taken from a plan view, overlaps a portion of the rear electrode layer of the other of the two adjacent unit solar cells with the insulating substrate interposed therebetween, at least one of said portion of the first electrode layer and said portion of the rear electrode layer forming an extending portion which extends outward from either the remaining portion of the first electrode layer or the remaining portion of the rear electrode layer, and
• wherein the first electrode layer of the one of the two adjacent unit solar cells is electrically connected to the rear electrode layer of the other of the two adjacent unit solar cells via at least one connection hole passing through the insulating substrate and being connected to the extending portion, such that the plurality of unit solar cells are connected in series to one another.