Solid state/energy: Solar-cell systems that work: In applications from irrigation pumps to village power systems, photovoltaic installations are now producing electricity economically

A national park in Utah derives all its electricity from silicon solar cells. A house in Massachusetts - far from the Sun Belt - draws at least SO percent of its electrical needs from the sun via a photovoltaic array on its roof. At an 80-acre farm in Nebraska, a photovoltaic system pumps water for irrigation in the summer and fans air for crop drying in the fall. The three solar-cell installations have this in common: they are working examples of the major categories of photovoltaic applications of the future - perhaps the near future.