Solar Energy Summary

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Solar technology can be used for space heating and cooling, to generate electricity, or in various industrial and scientific applications such as drying, desalination, and manufacturing. It also can provide power to operate electrical appliances, and for telecommunication and lighting in remote areas. For solar energy to capture a major utility market share, large power plants with capacities comparable to a coal or nuclear plant in the range of 100-200 MW must be developed. The major drawback of solar energy is the diffuse nature of sunlight that requires a large surface area for capturing enough light. Another problem is that solar energy is intermittent, available only during daylight and in favorable atmospheric conditions. One way to address this difficulty is to store the power in large, bulky, and expensive batteries. Another is to design a pumping storage water facility that stores water in an elevated reservoir during the day and releases it downhill to turn a water turbine and a generator as needed. Many homes use a backup system to supplement their primary solar systems when necessary.

Compared to current PV technologies with typical efficiencies of 5-17%, solar thermals are more efficient and can reach efficiencies of up to 30%. Unlike solar concentrating technologies that rely on direct radiation, photovoltaic cells rely mainly on indirect radiation and therefore can be used in areas with few hours of sunlight.

Currently, none of the solar electric generating stations can compete economically with the low cost of electricity generation using conventional coal and nuclear power plants. Both the capital and the operating costs are much higher, and the solar stations take up a much larger land area. Further research is needed to design larger heliostats and mirrors, as well as lenses with better optical properties and lower costs.



(1) Toossi Reza, "Energy and the Environment:Sources, technologies, and impacts", Verve Publishers, 2005

Additional Comments

Further Reading

Markvart, T., and Castanar, L., Solar Cells: Materials, Manufacture and Operation, Elsevier Publishing Company, 2005.

Galloway, T., Solar House, Elsevier Publishing Company, 2004.

Stine, W. B., and Harrington, R. W., Solar Energy Systems Design, John Wiley and Sons, Inc., 1985.

Solar Energy, Direct Science Elsevier Publishing Company, the official journal of the International Solar Energy Society, covers solar, wind and biomass energies.

External Links

National Renewable Energy Laboratory: Solar Research (http://

Energy Efficiency and Renewable Energy: Solar Energy, US Department of Energy (

American Solar Energy Society (

Solar Electric Power Association (

California Solar Center (