Solar panels and other types of solar-power generating equipment are more common now than they used to be. Driving around residential neighborhoods in San Diego and across the United States, shiny black solar panels can be seen on the roofs of many homes. Many commercial buildings also house solar power systems to generate clean, green electricity right from the sun.
But do you really know how solar energy works?
Solar Energy 101
The solar cells you see on rooftops are using the same technology as the hand-held calculator you might have used to do math homework in high school. Photovoltaics (photo meaning "light" and voltaic meaning "electricity") are inside the shiny black panels that power small calculators instead of batteries.
They also have been used in outer space to provide power to satellites' electrical systems since the late 1950s. Now, that same power-generating technology is helping residential and commercial property owners reduce or eliminate their electrical bills with environmentally friendly solar power.
Consider this: On clear sunny day, the sun's rays give off approximately 1,000 watts of energy for every square meter of the planet's surface. Solar power gives residents the opportunity to harness enough of that free energy to generate solar power.
Photovoltaic Cells: Your Personal Power Generators
Photovoltaic cells convert sunlight directly into electricity. They are made of silicon and other special materials, also called semiconductors.
When sunlight hits the solar cell, some of the light is absorbed by the semiconductor material. The energy of the absorbed light is then transferred to the semiconductor, which frees the electrons in the light, allowing them to flow freely.
The cells also have one or more electric field that forces electrons freed by light absorption to flow in a certain direction. This current of electrons is harnessed by metal contacts placed on the top and bottom of the cell, which can draw that current off for external use, such as to power a home or business.