What is the history of solar energy

Solar energy development

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Development of solar energy

The enormous potential of solar energy was discovered early on. Even the ancient Egyptians showed the first signs of passive solar energy use in their architecture. For example, they arranged doors so that they did not point south as possible in order to keep out the hot midday sun. In cooler regions, however, the midday sun was often used to warm the premises. Here windows and doors are oriented as much as possible so that the warming rays of the midday sun can be optimally used.

With the help of technical aids and facilities, so-called solar technology, it was only in modern times that it became possible to use solar radiation in a targeted manner to generate heat and electricity.

Electricity from solar energy

The French physicist Henry Becquerel laid the foundation stone that made it possible to use solar energy to generate electricity back in 1839. It was then that he discovered the photoelectric effect - he found out that electricity flows between two electrodes that had previously taken an acid bath. as soon as one of the electrodes has been exposed to light.

Almost 50 years later, in 1887, it was up to the German physicist Heinrich Hertz to find out that the electrical spark between two electrodes of a spark inductor jumps more easily when one of the electrodes is illuminated with UV light. One of his students researched further and discovered that zinc plates irradiated with UV light could even generate a weak current.

It was not until much later, in the 1950s, that the vacuum photocell built by Charles Fritts at the end of the 19th century, which at that time still consisted of vapor-deposited selenium layers, was further developed into a silicon solar cell by the US company Bell. Your efficiency: 6 percent. A fantastic breakthrough at the time.

In the meantime, silicon solar cells for solar power generation have efficiencies of up to 24 percent thanks to constant further development under laboratory conditions. That is very close to the theoretical maximum efficiency of 28 percent.

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Hot water and heating through solar energy

The principle according to which solar thermal energy is still used today also stems from a long time ago. Burning mirrors and concave mirrors were already known in ancient times to convert solar energy into heat that can be used specifically for humans. The best example of this: the Olympic torch, which has been lit by means of burning mirrors since ancient times.

However, the forerunner of today's solar collectors for hot water preparation and living room temperature control dates back to the 18th century. The French naturalist Horace-Bénédict de Saussure built a wooden box with a black bottom and a glass cover. Inside this simple “solar collector” it reached a temperature of 87 degrees Celsius.

It was not until the middle of the following century that Augustin Mouchot took up this simple invention again and developed it further. To do this, he combined the construct with a burning mirror and exhibited his solar steam engine at the World Exhibition in Paris in 1878. His suggestion to convert solar energy into electrical energy with the help of this solar steam engine was hardly taken into account. There was too great a skepticism that this would generate enough energy in the “sunless” Central Europe. In addition, there was the fact that fossil fuels were plentiful and inexpensive. It was not until the oil crisis in the 1970s that the idea at the time came back on the scene. Since then, solar hot water preparation and heating support have been standard in environmentally conscious building.


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The role of politics

A large part of the expansion of solar energy contributed not only to increasing environmental awareness and knowledge about the finiteness of fossil fuels, but also to legislation. With the introduction of the Electricity Feed Act in 1991, the government in Germany passed a minimum remuneration for feeding in electricity generated from renewable energies.

The generation did not cover costs, at least for solar power. But for electricity from wind turbines, which led to the wind power boom. When the existing law was replaced in 2000 by the Renewable Energy Sources Act (EEG) in conjunction with the 100,000 Roofs Program, funding increasingly focused on small solar systems, which was a decisive factor in the expansion of solar energy.

With the second amendment to the EEG, which came into force in 2009, not only electricity generation from renewable energy sources was considered for the first time, but the use of renewables in heating and cooling was also included. Solar energy became more and more affordable for private households and thus also stimulated the industrial side to constant further development and mass production of the individual technologies.

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Tags:Solar energy, solar energy