Each hour the sun beams enough energy onto the earth to satisfy global energy needs for a
year. Today’s solar energy technology is able to capture less than one tenth of one percent of
the global energy needs. The most well-known technology for solar energy is photovoltaic cells.
These cells are made of semiconductor materials like those in computer chips. When sunlight
hits the atoms in the cells, it knocks off electrons; when these electrons move about the cell,
they generate electricity. Solar thermal power plants exist and they generate electricity on a
much larger scale. They concentrate the sunlight in various ways to provide heat to boil water
which then has the ability to turn a turbine and generate electricity like what is done in a coal or
nuclear plant. This can provide electricity for thousands of people. Other more passive ways
exist. Some buildings are equipped with heat-absorbent materials that sit near big south-facing
windows and release their heat at night to heat the building. Similarly, absorbent plates on a
roof can heat liquid to make hot water for home usage. Solar energy is seen as inexhaustible
and is pollution and noise free. It is also very versatile as the technology is just as easily used in
outer space or remote locations as cities and future cars. Solar energy has some major
drawbacks though: it cannot be used during the night without a battery, cloudy days render
panels useless, they are expensive, and a great deal of land area is needed to provide large-
scale electricity. Even with these drawbacks, solar energy has grown at a rate of 20% each year
over the past 15 years, mostly due to rapidly falling prices and gains in efficiency. Japan,
Germany and the US are major markets for solar cells. With tax incentives, solar energy can
likely pay for itself in five to ten years.