Solar energy, radiation from the Sun capable of producing heat, causing chemical reaction, or generating electricity. The total amount of solar energy incident on Earth is vastly in excess of the world’s current and anticipated energy requirements. If suitably harnessed, this highly diffused source has the potential to satisfy all future energy needs. In the 21st century solar energy is expected to become increasingly attractive as a renewable energy source because of its inexhaustible supply and its nonpolluting character, in stark contrast to the finite fossil fuels coal, petroleum, and natural gas.
The Sun is an extremely powerful energy source, and sunlight is by far the largest source of energy received by Earth, but its intensity at Earth’s surface is actually quite low.
This is essentially because of the enormous radial spreading of
radiation from the distant Sun. A relatively minor additional loss is
due to Earth’s atmosphere and clouds, which absorb or scatter as much as 54 percent of the incoming sunlight. The sunlight that reaches the ground consists of nearly 50 percent visible light, 45 percent infrared radiation, and smaller amounts of ultraviolet and other forms of electromagnetic radiation.
The potential for solar energy is enormous, since about 200,000 times
the world’s total daily electric-generating capacity is received by
Earth every day in the form of solar energy. Unfortunately, though solar
energy itself is free, the high cost of its collection, conversion, and
storage still limits its exploitation in many places. Solar radiation
can be converted either into thermal energy (heat) or into electrical energy, though the former is easier to accomplish.