The Sun, our star king, has been with us for more than 5000 million years. It increases in intensity in summer, and in areas like the Mediterranean it contributes to creating our characteristic landscape and climate. But have you ever stopped to think what an incredible source of natural energy the Sun really is?
Solar energy in Spain represents about 10% of the electricity consumed in the country, ranking sixth worldwide and first in Europe in terms of production. A commitment to environmental sustainability contributes to a progressive rise in the generation and use of this energy.
What is solar energy?
Solar energy involves harnessing energy from the Sun to produce electricity or generate heat. It is a clean and unlimited energy that takes advantage of the electromagnetic radiation emitted by the Sun and that reaches Earth.
In the interior of the Sun the pressure is very high and temperatures exceed millions of degrees. These phenomena give rise to nuclear fusion processes, where hydrogen atoms fuse to create a helium atom. Fusion releases a huge amount of energy into space and some of it reaches our planet.
By using solar panels (photovoltaic panels) and collectors (thermal panels) we can transform this radiation into electricity and heat.
Types of solar energy and how they work
Of all the energy released by the Sun after nuclear fusion, electromagnetic waves reach us in the form of two main types of radiation:
- Direct radiation: what we see in areas directly illuminated by the Sun.
- Diffuse radiation: what we receive on cloudy days, radiation dispersed by the atmosphere and that reflected by the air, dust or different surfaces.
The function of solar panels and collectors is to collect part of that solar energy and transform it into clean and sustainable energy. Depending on how this solar energy is used, it is classified into three different types: Solar thermal energy, photovoltaic solar energy and passive solar energy.
Solar thermal energy
This is solar energy transformed into heat energy or calories through collectors. In general, solar thermal energy operates much more simply than photovoltaic energy.
Collectors, or solar thermal panels, contain a liquid inside that heats up quickly when exposed to the Sun's radiation. Then a pumping system transfers the mixture to a heat exchanger to take advantage of the energy to heat the sanitary water and heating circuits.
Collectors are generally black or blue plates that contain a mixture of water and an antifreeze. They are mainly used for domestic heating and for heating water in all types of installations, from swimming pools to entire buildings.
In some cases, these systems are installed accompanied by a small photovoltaic panel to produce the electricity needed for the pumping system. This provides a system that takes even more advantage of solar energy.
Photovoltaic solar energy
Photovoltaic solar energy enables us to obtain electricity as a result of solar radiation interacting with the photovoltaic cells used to make the solar panel. To find out how a photovoltaic solar panel works go to our website, but here is a general description of the process.
Sunlight impacts solar cells that are made of two layers of silicon separated by a semiconductor. Once they receive the impact of photons from light rays, an electron moves from one of the silicon layers (N layer) generating an electric current, which is known as the photovoltaic effect.
The first solar panels were capable of generating very little electricity and were mainly used in space satellites. However, recent improvements in efficiency enable it to be used both in self-consumption electricity systems with solar panels, and in solar power plants.
Passive solar energy
Passive solar energy consists of taking advantage of sunlight directly, without the need for a technology that acts as an intermediary, unlike what happens with thermal and photovoltaic energies.
This was the first way we were able to harness solar energy. So traditional drying of food by exposing it to the sun and obtaining salt by evaporating seawater were the first examples of taking advantage of the sun's energy.
Nowadays, the installation of greenhouses and the construction of ecological housing also involves using smart design and orientation so as to make the most of this natural energy source. One more example of how passive solar energy can be used to reduce the use of energy and to improve our quality of life.
An unusual fact: Already in 1866, Augustine Mouchot included mirrors inside a metal boiler with water inside to collect and concentrate the rays of the sun. This was the first parabolic collector used to drive a steam engine.