A solar cell system includes a number of P-N junction cells, a number of inner electrodes, a first collecting electrode and a second collecting electrode. The number of the P-N junction cells is M. M is equal to or greater than 2. The M P-N junction cells are arranged from a first P-N junction cell to an Mth P-N junction cell along a straight line. The P-N junction cells are arranged in series along the straight line. The number of the inner electrodes is M−1. At least one inner electrode includes a carbon nanotube array. A first collecting electrode located on an outside surface of the first P-N junction cell. A second collecting electrode located on an outside surface of the Mth P-N junction cell. A photoreceptive surface is parallel to the straight line.