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.
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.
Turning the sun's power 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.