It is noted that the wide acceptance and utilization of the photovoltaic generation of electrical power largely hinges on the ability to decrease the cost of production of solar cells and panels while at the same time increasing their conversion efficiency. A short tutorial is given on solar cells that are presently being investigated for cost reduction and efficiency improvement. The many types of cells are under investigation as well as the wide range of materials are examined. Efficiency improvements that have been achieved for many types of cells that are potentially low cost in large-volume production are described. >