There are different ways of how solar energy can be harnessed, then we will analyze these aspects.
HOW SOLAR ENERGY CAN BE HARNESSED
The Sun, source of life and origin of the other forms of energy that man has used since the dawn of History, can satisfy all our needs, if we learn how to take advantage of the rational light that continually spills on the planet.
During the present year, the Sun will throw on the Earth four thousand times more energy than the one we are going to consume. This energy can be used directly, or can be converted into other useful forms such as, for example, electricity using solar panels (photovoltaic) that convert the sun’s rays into electricity
What is solar energy?
We all know that solar energy is the energy produced by the sun and that it is converted to useful energy by the human being, either to heat something or produce electricity (as its main applications).
Each year the sun throws 4 thousand times more energy than the one we consume, so its potential is practically unlimited.
The intensity of energy available at a given point on the earth depends, on the day of the year, on the hour and on the latitude. In addition, the amount of energy that can be collected depends on the orientation of the receiving device.
It is currently one of the most developed and used renewable energies in the world.
What is the importance of solar energy?
Solar energy is what reaches the Earth in the form of electromagnetic radiation (light, heat and ultraviolet rays mainly) from the Sun, where it has been generated by a nuclear fusion process.
The use of solar energy can be done in two ways:
- By high temperature thermal conversion (photothermal system) and
- By photovoltaic conversion (photovoltaic system).
What is the thermal investment?
High temperature thermal conversion consists of transforming solar energy into thermal energy stored in a fluid. To heat the liquid, devices called solar collectors are used.
It is a non-polluting energy and provides cheap energy in non-industrialized countries.
What are the inconveniences?
It is an intermittent energy source, since it depends on the climate and the number of hours of sunshine per year. In addition, its energy efficiency is quite low.
Brief review on solar energy
It is interesting to look back and see how the sun’s energy has been used in the past.
Up to the solar panels full of sensors that we know today has gone through many phases and designs of the most disparate always seeking to take advantage of the large amount of energy that the sun king brings each day to our planet.
The first historical reference that can be found to the use of solar energy is found in ancient Greece with Archimedes. During the battle of Syracuse in the third century BC that confronted the Romans and the Greeks, some writings relate how Archimedes used hexagonal mirrors made of bronze to reflect the sun’s rays concentrating on the Roman fleet with the aim of destroying it.
Many centuries later, Leonardo da Vinci also thought about the use of the sun. In 1515 he started one of his many projects, although this would be one that would never end. His idea was to build a 6-kilometer diameter concentrator based on concave mirrors for industrial steam and heat production.
In the mid-eighteenth century, Georges-Louis Leclerc, Count of Buffon, fascinated by the accounts of the Syracusan war and the mirrors of Archimedes, continued to investigate in that same field. To begin with, he used 24 glasses of glasses with which he realized that he could easily get a fire 20 meters away by lighting a combustible mixture of pitch and coal dust.
Then he decided to build a more ambitious apparatus in which he joined 168 pieces of glass 15 sideways, moving his goal to 50 meters again achieving his goal. After that, I create its definitive solar energy concentrator with 360 pieces of 20-centimeter glass.
Experimenting with it he realized that if he concentrated 120 of the crystals in a fuel 6 meters away, it burned immediately. At that same distance, with 45 mirrors could melt a clay jar and with 117 crystals could melt a silver chip.
How do we convert solar energy into useful energy for everyday use?
This renewable energy is used mainly for two things, although they are not the only ones, first to heat things like food or water, known as solar thermal energy, and the second to generate electricity, known as solar photovoltaic energy.
Water heaters and solar stoves are the main devices used in solar thermal energy.
To generate electricity, solar cells are used, which are the soul of what is known as solar panels, which are responsible for transforming electricity.
How do solar panels work?
Photovoltaic cells are manufactured with semiconductors. Semiconductors are elements that have a very small electrical conductivity, but higher than that of an insulator.
The most used are silicon, this is a very abundant material, hence its low cost. When the sun’s rays strike the cells, the P-N junction of the semiconductors along with their conducting metal helps produce energy.
At this juncture, the PN junction are positive and negative charges that help produce electrical current, due to a potential difference that is created when the cell is illuminated.
When the cell is short-circuited (ie the regions P and N are joined by a conductor with zero resistance) the electrons of the N region move through the conductor and join with the holes in the P region producing electricity thanks to the flux of electrons, this current will be maintained while the cell is illuminated.
Types of photovoltaic cell depending on the material
The cells can be made from three different types of materials:
Silicon mono crystalline: This material has an efficiency of 16 – 19%, has a uniform crystalline structure and is manufactured in cylindrical ingots that are later cut into thin sheets. A lot of energy is spent in its construction, it is used in industries.
Silicon poly crystalline: It has an efficiency of 13 – 15%, has a non-uniform crystalline structure. It is manufactured in rectangular molds and is cheaper than the crystalline monkey.
Amorphous silicon: The latter has an efficiency of 7 – 10%, has a non-crystalline structure and its power decreases as time passes, this type of material is very cheap.
The photovoltaic modules
A solar cell produces approximately 2w.
The modules have between 40 and 100 cells all connected to each other and the set of solar cells is called a photovoltaic module.
A module is formed by:
- Front cover
- Back cover
Types of installation
It can be installed in three different types of surface, which can be in:
Installation on the roofs of houses:
You can support the modules directly on the roof if it is made of tiles, if it is a roof you can put it before installing a support
Installation in large areas:
Large free areas are used to install solar panels, can be used for example parking, soccer fields.
Installation in large buildings:
They are installed, for example, on the façade of buildings (which have a considerable height) to take advantage of the direct radiation they receive and self-supply of electrical energy.
Method for storing thermal solar energy
The recent global warming becomes an increasingly serious problem and has a potential to threaten human survival in the future.
The main cause of this is considered carbon dioxide (CO2) released into the atmosphere from fossil fuels that have been used in large quantities as an energy source in the 20th century. Therefore, it is believed that the continued use of fossil fuels in the near future.
On the other hand, the increase in energy demand with the rapid growth in the so-called developing countries such as China, India and Brazil leads to the fear that the depletion of oil and natural gas, until now considered inextinguishable, by some, will result a reality.
Solar energy is very powerful as alternative energy, however, from a practical point of view, it has been considered necessary to solve the problems that the energy density of solar energy is low and the storage and transfer of solar energy are difficult .
The storage of electrical energy is sometimes a problem. The development of a battery to store electrical energy is a previously existing main theme and is being followed throughout the world.
However, even the most advanced lithium ion battery is not satisfactory with respect to the storage of a large amount of electrical energy, and a particular battery for a large amount of electrical energy needs to be developed in terms of safety.
Also, in the plant to obtain electric power energy from the sun’s energy, a massive thermal storage unit, an auxiliary boiler and the like, as well as the battery, are required in case the generation of energy is difficult due to to bad weather or similar, and this constitutes an enormous construction cost.
As described above, although efforts have been made to convert solar energy as the last sustainable energy into electricity, hydrogen or the like as the secondary energy currently in the world, there are major problems in the storage and transfer of such secondary energy. .
Unless the problems relating to the storage and transfer of energy are overcome, worldwide distribution as well as its use in a mobile body such as a vehicle, airplane or ship will be very difficult to achieve.
The method to store solar thermal energy includes:
a) Acquire thermal solar energy
b) Perform a reaction to produce hydrogen from water using a part of the acquired solar thermal energy, for example as a part of a heat source, a source of motive power and / or a source of electrical energy, particularly using the energy directly as a source of heat or as a source of electrical energy.
c) Perform a reaction to synthesize ammonia from nitrogen and hydrogen obtained in step (b) using another part of the acquired solar thermal energy, for example as a heat source, a source of motive power and a source of energy electrical, particularly using energy as a source of heat and / or a source of motive power.
According to this method of energy storage, ammonia is synthesized using solar thermal energy, so that solar thermal energy can be stored in the form of ammonia chemical energy.
The generation of electrical energy through the photovoltaic system constitutes a viable alternative, solar energy as a sustainable energy vector.
Solar energy is important because through photovoltaic electricity, it allows us to progress materially, enabling the creation of new life alternatives that bet on a greater respect for the environment and that are oriented towards self-sufficiency. Preventing pollution produced by the burning of fossil fuels, the increase of climate change, the greenhouse effect and that we are dependent consumers of countries that have large oil reserves.
The intensity of solar energy usable at a given point on Earth depends, in a complicated but predictable way, on the day of the year, on the hour and on the latitude. In addition, the amount of solar energy a receiving device can receive depends on the orientation.