Photovoltaics III: Concentrators: Focusing the sun's rays, using cheap, long-lived optics, will be exploited in direct sunlight regions

Considers photovoltaic concentrating systems, indicating the problems inherent in their use which are, namely, ensuring that the systems are reliable and long-lived and reducing the costs of the optical and tracking components. The author also presents the US Department of Energy's cost goals for concentrating systems and indicates the progress made towards reaching these goals. Performance characteristics of operating systems are presented.