The first 30 pages of theis typewritten book are generally useful as a timely, concise, well-documented statement of energy sources and expected energy usage in the U.S. to the year 2000. The rest of the book... deals with the use of solar energy through photovoltaic conversion. The principles of energy band structure of solids, the state of the art in photovoltaic conversion, economic considerations, and business opportunities are each discussed; extensive references and a bibliography are provided.