Solar Energy – How To Use It? April 19, 2021 April 19, 2021 Tim Collins

For a few weeks now, the day has been getting longer and spring begins today. This means that there will be more and more sun. Therefore, we asked ourselves the question – how to use solar energy?

The movement of celestial bodies, the position of the Earth in relation to the Sun, words unbelievably pleasing to the ear, such as perihelion and aphelion or all these spring-summer-autumn-winter solstices – we will not deal with all of these. For the purposes of this text, we simply assume that the Sun is shining, and because of the cosmic forces and principles in the cosmos, the Sun is sometimes closer to the Earth and sometimes further. And one day its rays fall more vertically on the surface of the Earth, and another day less vertically. First, let’s check …

How much energy does the sun give us?

The question is valid, since the Sun is a free source of energy. Well, inside our nearest star, thermonuclear fusion takes  place , which means that the nuclei of the lighter elements merge into heavier ones. Effect? In one second, the Sun produces a million times more energy than humanity uses in a year (sic!). Anyway, it’s sooooooooooooooooooooooooooooooooooooooooooooooooooooo full of energy.

Fun fact – do you know that the pull of the Sun is 28 times stronger than the pull of the Earth, so a man weighing 75 kg on Earth would weigh 2.1 tons on the Sun (you might find it useful someday in Millionaires).

All in all, solar energy is actually infinite. Yes, the sun will go out, but in a few billion years and we do not have to worry about it (although in the 2007 movie “Towards the Sun” it turned out that the sun is dying before our eyes, so a team was sent to throw a nuclear charge into it and it got them going, but it’s just science fiction and the source of some photos for this text :).

Besides, the sun rises beyond the horizon every day, no matter what. It is not tied to politics, economics, origins and anything else. The sun was, is and will be. If so, it would be good to know how to use this energy. The first way is …

Solar cells

Padają na nie promienie słoneczne, które zamieniane są w prąd. Wydaje się to bardzo proste, ale co naprawdę dzieje się w ogniwie? W ogniwie jest zazwyczaj półprzewodnikowa płytka, najczęściej krzemowa, albo taka z tellurku kadmu (CdTe) lub mieszaniny miedzi, indu, galu, selenu (CIGS).

The sun’s rays falling on the cell, i.e. in fact particles called photons (with energy greater than the width of the semiconductor gap), knock out electrons from the negative part of the plate (n – negative side). In this way, holes, i.e. places with a positive charge, are formed. Both charges are separated by a potential barrier (pn junction), so we deal here with a potential difference. This is what makes the electrons start to move in an orderly manner and voila, thanks to the so-called photovoltaic conversion, the current flows in the device.

Phew, we got through this complicated technical description. It is worth mentioning, however, that the photovoltaic effect was discovered in 1893 by Becquerel. Since then, there has been a huge development of this technology. First of all, their efficiency increases. Depending on the technology used, the efficiency of PV cells ranges from 10 to even 46% (those that can be mounted on the roof usually reach 15-20%). In addition , solar energy is the cheapest source of electricity in 60 countries . No wonder that Al Gore is an optimist for the climate , since the power of solar panels is constantly growing and prices are falling.

Other ways to use solar energy

There is also such a thing as photothermal conversion. It is the conversion of solar radiation energy into thermal energy. There is passive and active photothermal conversion. Passive is one in which the flow of the heat carrier (for example air or heated water) takes place only by convection, while active conversion uses pumps powered by additional energy sources.

The latter type of conversion is in the form of solar collectors (called solar cells). They are used to heat hot water in homes, hotels or swimming pools (sometimes they even support heating). There are flat and vacuum collectors (they differ slightly in construction and efficiency). The largest solar collector system has recently been built in the Danish town of Silkeborg. It consists of 12,436 solar panels, which make it possible to meet 1/5 of the annual heat demand of the entire town with over 40,000 inhabitants. Not bad.

There are also special, mobile focusing collectors, the so-called mirrors that reflect the sun’s rays so as to focus them in one point. For what? Well, to heat the heating medium (molten salts – sodium nitrate and potassium nitrate) in a solar tower. The largest power plant of this type is located in the Mojave Desert in California (and where else ) and has a capacity close to one block of the Bełchatów power plant (392 MW).

There is still the problem of water thermolysis. What is this devil? At high temperatures, we deal with the thermal decomposition of water vapor into oxygen and hydrogen ( hydrogen can be refueled and driven blue ). There is no problem with high temperature in this case, because many mirrors focusing the sun’s rays in one place are enough. The problem is the separation of the gases formed in this way, the more so as they burn again when the temperature is lowered (return to water). Thermolysis is expensive, wastes a lot of energy and has a low efficiency. Solar PV conversion is therefore the best solution when it comes to harnessing solar energy.

Energy from the sun – advantages

The advantages of solar energy are its immutability (the sun rises every day), universality (the earth is bathed in sunlight), unimaginable abundance (as we wrote, in one second the sun produces a million times more energy than humanity consumes in a year) and zero emissions (energy from the sun does not emit any pollutants when it is produced – the solar wind is not pollution)

Solar energy is the energy of the future

But whatever, the future of green energy is primarily solar energy that is converted into electricity. Photovoltaics has been taming the sun for over 60 years, and its power is still increasing and will continue to grow. More than 1/3 of the energy in American sockets comes from the wind  and the sun. And last year, the Chinese became its largest producer , thus becoming the most enlightened nation in the world 🙂

Other sunny news? The greatest visionary of our time – Elon Musk – offers  solar roofs , and Lodz students drive their  car to the sun . By attaching the  socket to a sun-drenched glass , energy can be generated, while the Japanese build  solar farms on the water . After all, in the skies, a solar-powered plane is already flying . In fact, an ecologically and politically inspiring woman in France even builds roads with solar panels . Little?

New technologies will allow us to forget about phone chargers in the near future, because the phones will have a screen made of a special type of cell ( Dr. Olga Malinkiewicz has already patented this technology with the use of perovskites ). There will probably also be photovoltaic paints, clothes with energy-producing elements ( will they be recycled? ). And the solar panels on the roofs of our electric cars will be quite obvious . So – the sun is sending a mass of clean, free and uninterrupted energy towards the Earth. We should therefore use it.