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Solar energy: what it is, how it works and its advantages

Solar energy is one of the main sources of green energy. It harnesses the Sun's radiation to produce electricity and heat.

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.


Advantages and disadvantages

Solar energy has been shown to be an energy source in clear ascent in recent years, together with many other renewable energies. Technological progress and research are being used to maximise its advantages and minimise its disadvantages, for a more sustainable future.


Disadvantages of solar energy

  1. Medium-high initial cost: the initial production cost is high, although once the necessary infrastructure has been prepared, energy generation is profitable in the short term.
  2. Energy for immediate uses: another disadvantage of solar energy is that it is difficult to store so it is usually for instant use. Although battery technologies are advancing fast, it is still difficult to store large amounts of electricity for later use.
  3. Dependence on climatology. As a source of energy that depends directly on the Sun, the ability to produce depends greatly on the seasons, the hours of daylight and the climatology of the place where the panels are installed.


Advantages of solar energy

  1. Inexhaustible energy: our sun has more than 6,000 million years of life left, so we are talking about an inexhaustible source of energy.
  2. Sustainable energy source: the production of solar energy contributes greatly to the reduction of CO2 emissions and the protection of the environment. Progress is also being made in the recycling processes for panels when their useful life has ended.
  3. More economical electricity: although the initial investment is costly, improvements in the efficiency of solar panels enables the investment to be recovered increasingly quickly. This means that we can obtain electricity for consumption at an increasingly lower cost.
  4. Aid for economic development: the implementation systems taking advantage of solar energy is not just a source of qualified employment for society. It also contributes to having a more efficient energy system that improves the productivity of companies that use this type of energy.


 How can I consume solar energy?

Interest in solar energy, as well as other renewable energies, is a clear sign that consumption habits are changing and there is increased concern for the environment in which we live. More and more people are deciding to consume this type of energy taking advantage of a number of alternatives that we have at our disposal:

  • Self-consumption systems: This consists of installing photovoltaic panels in your home. This is how you can take advantage of the hours of sunlight to generate part or all of the electricity you need in your daily life. Currently there are really efficient systems that enable you to have photovoltaic solar panels with a very low initial investment.
  • Ecological electricity tariffs: For many users it is difficult to install panels individually and in many cases it cannot be done efficiently in a community of neighbours. In these cases the best alternative is to have an ecological electricity tariff that guarantees that all the electricity supply comes from renewable sources such as solar energy.

Continuous advances in research are making solar energy an increasingly economical and efficient alternative. It is this great commitment to green and clean energies like solar energy that marks the path that we have taken in Endesa together with you for a much more sustainable world.

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