When light strikes the exposed active surface, it knocks electrons loose from their sites in the crystal. Because the current and voltage obtained from these devices are small, they are usually connected in large series-parallel arrays. Although cells constructed from indium phosphide and gallium arsenide are, in principle, more efficient, silicon-based cells are generally less costly. Solar cells have long been used to provide electric power for spacecraft. Appreciation of photovoltaic power is part of the shift toward an appreciation of the elegance of the solid state that plants possess.
Plants practice photosynthetic solutions to the problems of power acquisition.
Yet this is, in fact, the principle upon which photosynthesis operates. High efficiency photovoltaics could today meet the daily needs of most people for electricity. It is the running of basic industries on solar energy that has proved difficult. Perhaps this is nature's way of telling us that we aspire to too much manufacturing.