In view of the world＇s ever-increasing demand for energy, limitation of usable fossil fuels and the impact of large exhaust pollutant on the environment during their use, there is an urgent need to exploit new energy sources that are plentiful, renewable and clean. This paper introduces briefly energy source technologies now available, centres on the analyses of direct utilization of solar energy, solar cells and the decomposing water by solar energy from the optical and optical technological point of view. Direct utilization of solar energy can be expanded through a system of tracing and focusing sunlight with simplicity and low cost in combination with the heat-resisting, broad band transmissive, low-loss and inexpensive hollow-core plastic fibers. In solar cell field, the stress should be put on the research for various film solar cells except for improving the efficiency and reducing the cost for crystalline silicon solar cells. In decomposing water by solar energy, in order to obtain hydrogen, the stress should be put on the research for decomposing water by light catalysis. By means of transforming solar radiation spectrum into brightness maximum to be located in infrared region by using the cavity radiator, the most spectra can be absorbed by water, and which provides a new technological way to be probably worthy of exploration.