Typical solar cells use expensive rare earth minerals, e.g. silicon-bases solar cells. Researchers at Stanford University have come up with an alternative method of creating solar cells made entirely of carbon. It is thin film prototype made of carbon materials that can be coated from solution. In future, flexible carbon solar cells could be coated on the surface of buildings, on windows or on cars to generate electricity. It can lower manufacturing costs. In the solar cells, the electrodes are made of graphene consisting carbon nanotubes which are 10,000 times narrower than a human hair. These have extraordinary electrical conductivity and light absorption properties. Carbon prototypes absorbs near infra-red wave lengths of light, contributing to a laboratory efficiency of one per cent, much lower than commercially available solar cells. We have a long way to go.