(Mariusika11/iStock)
There are two types. The first uses sunlight only for heating, usually water. “This plate consists of a dark surface, which absorbs energy from the Sun and transforms it into heat”, says engineer José Kleber da Cunha Lima, from USP’s Polytechnic School.
The other type of solar panel is one that converts the sun’s energy directly into electricity. It is composed of solar cells, made of semiconductor materials such as silicon. These are called photovoltaic cells. When the particles of sunlight (photons) collide with the atoms of these materials, they cause the displacement of electrons, generating an electric current, used to charge a battery. The photovoltaic effect was discovered in 1887 by the German physicist Heinrich R. Hertz (1857-1894). Electric generators like these are increasingly used in electronics and satellites.
Outside the Earth’s atmosphere, a system of solar panels is capable of absorbing 14% of the solar energy that falls on them. Each square meter of collector provides 170 watts (slightly less than three standard 60-watt light bulbs).
The energy that comes from above
Particles of sunlight displace electrons from the semiconductor plate, generating electricity
1. The photons (particles of sunlight) collide with the atoms of the semiconductor material that covers the plate
2. The shocks displace the electrons in the semiconductor
3. The generated energy is used to charge a battery