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Endesa - Electricity, Gas, People

How electricity is produced (part 3)

Publicado el (EN) 10 Diciembre 2017
Cómo se produce la energía eléctrica (Parte 3): solar

The sun can be our greatest source of cheap, clean, renewable energy. We must take advantage of the more than five billion years of life that still remain to it. We’ll explain how the rays of the sun are turned into electricity for your sockets.

We’ll follow our accelerated course to learn where electricity comes from. Today’s lesson is a case study about the sun, the greatest generator of energy ever known.

How are its rays transformed into the electricity found in light bulbs? By magic? No. It’s just science.

We are going to focus on photovoltaic solar power, which is used the most and directly transforms solar radiation into electricity. However, there is also thermosolar energy, which uses the heat from the sun to raise the temperature of water until it generates the steam that moves a turbine.

Photovoltaic energy

To transform sunlight into energy, metal semi-conductor sheets are needed: these are called photovoltaic cells.

These cells have one or more layers of a semiconductor material and are covered with a transparent glass that allows radiation to pass through and minimises heat loss.

The solar panels that can be seen on the rooftops of many houses are made up of these photovoltaic cells. Although their installation may seem expensive, data indicates that the purchase pays off with savings of around 30% on long-term consumption (25 years), which means paying between €20,000 and €30,000 less. Another of their advantages is that they do not require much maintenance.

The power of the sun converted into electricity

The rays of the sun are made up of photons which enter, the photovoltaic cells of the panel, generating a field of electricity and therefore, an electrical circuit, between them. The more intense the light, the greater the flow of electricity.

The photovoltaic cells convert the sunlight into electricity in the form of continuous current, and with a graduation that varies between 380 and 800 watts. To improve the result obtained, an inverter is used that transforms this energy into alternate current, which is what we use in our houses.

Finally, this alternate current passes through a counter that quantifies it and supplies it to the general network of electricity.

Where do photovoltaic cells come from?

The father of this energy was the French physician Edmond Becquerel, who at the age of only 19 built the first photovoltaic cell in the world in 1839.

Shortly afterwards, in 1883, the American inventor, Charles Fritts developed the first solid cell by covering the semiconductor selenium with a thin layer of gold to form the connections. His device only obtained 1% efficiency, but its structure paved the way for what we refer to today as the sustainable transformation of solar energy.

Solar photovoltaic energy will be the cheapest source of electricity in the world.

Uses of solar energy

Electricity produced by photovoltaic cells can be used in:

  • An isolated installation. Solar energy supplies electricity to places that are difficult to access, where for example, power lines have not been installed. This electricity is intended for self-consumption.
  • An installation connected to the grid. The energy produced is loaded into the electrical grid, as though it were just another generator. Meanwhile, owners continue to purchase the electricity consumed at the same time as they sell what they produce.
  • Satellites. They orbit around Earth and have solar panels on their structure to take advantage of the energy provided by the sun.
  • Independent structures. Thanks to solar panels, many small infrastructures can benefit and be self-supplied with energy from their own resources: radio and television repeaters, SOS posts on motorways, radars, military structures, forest monitoring posts, switching centres, etc.

The future is solar

According to the International Energy Agency, solar photovoltaic energy will become the cheapest source of electricity in many countries during the coming decades. In addition, photovoltaic systems have a long useful life, given that they are expected to last an average of 30 years (with a performance of above 80% after 25 years). If that weren't enough, all of their components can be recycled.

According to the International Energy Agency, solar photovoltaic energy will become the cheapest source of electricity in many countries during the coming decades. In addition, photovoltaic systems have a long useful life, given that they are expected to last an average of 30 years (with a performance of above 80% after 25 years). If that weren't enough, all of their components can be recycled.

In terms of their downside, their intermittent nature (Those damned clouds! Pity about the night-time!) and storage problems are the main disadvantages of solar energy. However, technology is paving the way to fix these problems, by developing increasingly long-lasting batteries and investigating how to install panels wherever the sun shines... In outer space.

A photovoltaic installation has an average lifetime of 30 years.