How Sun Becomes Electricity
Up with the Sun
Over the years, one of the key ingredients in farming, energy from the sun, has become a crop itself. Solar energy is simply the sun’s rays that reach the earth. These rays can be converted to electricity in a couple of ways. Solar power plants use an indirect method where heat from solar thermal collectors warms a fluid, producing steam that is used to power a generator. A more direct process uses Photovoltaic devices, or solar cells. These devices convert sunlight directly to electricity using solar cell technology capable of providing power on a small scale (ie. watches, road signs, calculators, etc.) or on a much larger scale, such as entire cities.
As advances in traditional farming are constantly leading to greater efficiency and larger yields, photovoltaic energy holds great potential for technological advancement in energy and operational efficiencies. The simplified process offers minimal environmental impact, eliminates the need for water and provides limitless opportunity for further improvement in efficiency and cost reduction.
Squeezing energy from the sun
Harvesting the sun begins when sunlight hits a solar cell. The cell absorbs a portion of the suns energy causing the electrons in the cell to become “excited.” With the help of electrical fields within the cell, these “freed” electrons move together toward the front of the cell. The current created by these moving electrons is then collected by metal conduction strips, from which it can be extracted for external use.
When generating utility-scale photovoltaic solar power, solar cells are electrically connected to one another in a module. These modules can then be gathered with others to form and array.
Nourishing our lives
Of course, how the harvest works isn’t as important as whether our not we’re providing enough of the energy we need. The Average U.S. household typically uses between 6,000 and 10,000 kilowatt-hours (kWh) of electricity per year. Since one megawatt of solar energy can generate roughly two million kWh each year, that one megawatt of solar provides enough electricity to satisfy the needs of 200 to 300 households per year.
For more information on photovoltaic solar power, please visit the Energy Information Administration at www.eia.doe.gov.