Patent ID: 8288648

Claim:
A solar cell, comprising: a substrate configured to have a plurality of via holes and a first conductive type; an emitter layer placed at a first surface of the substrate and configured to have a second conductive type opposite to the first conductive type; a plurality of first electrodes on the emitter layer and coupled to the emitter layer; a plurality of first current collectors placed at a second surface of the substrate and into the plurality of via holes, and coupled to the first electrodes through the plurality of via holes, the second surface being opposite to the first surface with respect to the substrate; a back surface field unit placed at the second surface of the substrate; and a plurality of second electrodes placed on the back surface field unit and coupled to the back surface field unit, wherein the plurality of via holes comprise at least two via holes having different angles, and the at least two angles are determined by the position on the substrate where the at least two via holes are formed.