The gradually worsened polution day by day and the large scale consumption of naturaal resources load more and more serious pressure in society and economy to the world,as a result,people began to pay more and more attention to energy-saving and environmental protection. The experts thought that our human beings should find the new replacing energy as soon as possible and in the renewable energies,the solar energy will be the first choice for replacing.Acdording to measure and calculation,the energy released by the sun each second equals to that released by burning 128 million tons standard coal and the energy it radiated to the surface of earth is about 17000 bullion kilowatt each second,equals to 35000 times larger than the total consumption of energy for one year of the whole world at present.Besides,the quantity,distribution universality,cleanness and technological reliability of solar energy are more excellent than that of other renewable energies such as wind energy,water power and biomass energy.