Polymer Solar cells being flexible, light weight, inexpensive, colorful and large area devices, portend potential for large scale grid power generation. The first major breakthrough in organic solar cell performance came in 1986 when Tang discovered that much higher efficiencies about 1% can be attained when electron donor (D) and electron acceptor (A) are brought together in one cell. With the discovery of photo induced electron transfer from a conjugated polymer to fullerene molecules in 1992, the bulk heterojunction (BHJ) polymer solar cell has become the most successful device structure developed in the field till date. Poly(3-hexyl thiophene) (P3HT) has been the subject of intensive investigations upto 2008 yielding power conversion efficiencies (PCEs) around 5-6%. OPV technology has grown during the past decade with cell efficiencies quadrupling. As alternative route of higher performance, two or more single cells can be combined in tandem structure. The most efficient tandem organic solar cell reported by Yang Yang's group has 8.62% power conversion efficiency (PCE) which has been further improved with an NREL – certified PCE of 10.6%. An overview of the above will be presented in this paper.