The Energy Information Administration shows this distribution for U.S. energy: petroleum - 39.8%, natural gas - 23.6%, coal - 22.8%, renewable energy - 6.8%, and nuclear - 8.4%. An argument can be made that the sun is responsible for almost all but the 8.4% of nuclear energy. Past sunlight created the biomass that eventually resulted in petroleum, natural gas, or coal. Renewable energy is hydroelectric, wind energy, geothermal, and direct solar. The obvious question then is why are we not attempting to use more direct solar energy?
Wiki tells that the first solar cell was produced by Charles Fritts in 1883, with an efficiency of 1%. In 1954, Bell Laboratories discovered that blank semiconductor material used to produce transistors, and later integrated circuits could convert light energy into electrical energy. These were quickly used in the 1960s space race for satellite panels.
For a terrific overview of today's solar panel technology, see The solar industry gains ground. SunPower is today selling panels with 22% efficiency, compared to the industry average of 16%. Their product is based upon crystalline photo voltaics, whereas the newcomers such as First Solar are exploiting thin film technology which should have much lower production costs.
Save hundreds with solar energy tells an Orlando, FL, family installed a solar panel array on their roof as a 5KW system. (See AllSolar for the residential product line.) For an investment of $43,000, the family saves about $200 a month in electricity. This illustrates the current business case problem of solar energy. With a return on investment less than 5%, it is difficult to justify unless there are generous tax credits. The tipping point for solar will be when the electricity cost from solar panels is the same as from the power grid. Some predict 2010 - we will watch expectantly.
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