The definition of solar energy is the energy that comes from the Sun and that we can capture thanks to solar radiation. The concept of solar energy is often used to refer to the electrical or thermal energy that is obtained using solar radiation.
This source of energy represents the primary energy source on Earth. Because it is an inexhaustible source, it is considered renewable energy.
From this energy, many other energy sources are derived, such as:
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Wind energy, which harnesses the power of the wind. The wind is generated when the Sun heats large volumes of air.
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Fossil fuels: they come from an extremely long process of decomposition of organic particles. The organic decomposers were largely photosynthesizing plants.
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Hydraulic energy, which harnesses the potential energy of water. Without solar radiation, the water cycle would not be possible.
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The energy from biomass, once again, is the result of the photosynthesis of plants.
This type of renewable energy is an alternative to fossil fuels that do not emit greenhouse gases such as carbon dioxide.
Examples of solar energy
Some examples of solar energy include the following:
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Photovoltaic solar panels generate electricity; these facilities are used in homes, mountain shelters, etc.
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Photovoltaic power plants: they are significant extensions of PV panels whose objective is to generate electricity to supply the electricity grid.
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Solar cars use PV cells to convert solar radiation into electricity to drive an electric motor.
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Solar cookers: they are made of a parabolic system to concentrate the sun’s light to a point to raise the temperature and be able to cook.
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Heating systems: with solar thermal energy, a fluid can be heated that can be used in a heating circuit.
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Swimming pool heating is a simple fluid circuit in which water circulates along a set of solar thermal collectors exposed to the sun.
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Calculators: Some electronic devices have a small solar panel to supply power to the electrical circuit.
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Solar ventilation is a type of solar energy that uses the sun's heat to ventilate a space. It is often used in homes and buildings to improve air quality and reduce energy costs. Solar ventilation can be used to ventilate a single room or an entire building.
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Photosynthesis is a natural way that plants use to convert solar energy into chemical energy.
Types of solar energy
There are three types of solar energy technologies:
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Photovoltaic solar energy: PV solar panels are composed of a material that, when solar radiation strikes, releases electrons and generates an electric current.
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Thermal solar energy: This system takes advantage of the heat capacity of the Sun’s rays. Solar radiation is converted into thermal energy to heat a fluid that can be used for heating domestic hot water. In solar thermal power plants, steam is generated and, subsequently, electricity.
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Passive solar energy is a resource to take advantage of solar heat without using external resources. For example, architects can orient houses and decide where to put windows, considering where solar radiation will be received. This technique is known as bioclimatic architecture.
How is solar energy produced?
From a physical point of view, solar energy is produced in the Sun through a succession of nuclear reactions. When this energy reaches us on Earth, we can take advantage of it in many ways:
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Solar panels with photovoltaic cells. Photovoltaic panels are made of a material that, when receiving light, directly ionizes and releases an electron. In this way, solar radiation is transformed into electrical energy.
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Using solar collectors that are designed to convert solar radiation into thermal energy. Its purpose is to heat a fluid that circulates inside. In this case, we do not have electricity, but we have fluid at a high temperature that can be used in many applications.
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Concentrated solar energy is a system that reflects all solar lighting to a focal point to reach high temperatures. This technology is used in thermosolar plants for energy generation.
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Passive solar energy systems use solar energy without any external energy input. For example, architectural designs allow maximum solar radiation in winter and avoid excess heat in summer.
Types of solar panels
The term solar panels is used for both methods (photovoltaic and thermal). In any case, the design is significantly different depending on what type of solar technology it is going to be used for:
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The solar thermal panel uses solar rays to heat a liquid that transfers heat to a fluid and then heats water. Solar water heaters are used in homes to obtain hot water.
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The photovoltaic panel exploits the properties of particular semiconductor elements placed in solar cells. Solar cells produce electrical energy when subjected to solar radiation. Thanks to the so-called photovoltaic effect, exposure to the sun causes the movement of electrons in a component (usually silicon), generating a continuous electric current.
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The concentrating solar panel also uses a series of parabolic mirrors with a linear structure. The objective of these mirrors is to concentrate solar radiation to a focal point to reach temperatures high enough to generate steam.
Uses of solar energy
Solar energy has many uses and applications that can be summarized in three points:
Domestic hot water DHW
Solar water heating is used to supply domestic hot water (DHW) and heating to homes and small building complexes. Solar power plants have been built that, using steam turbines, convert the stored heat into electricity.
However, these prototypes have not been widely used due to the low performance of these power plants compared to the high costs and the irregular electricity supply.
Electricity generation
Photovoltaic panels are used in isolated solar systems to power devices away from electrical networks (space probes, high-altitude telephone repeaters, etc.). They are also used in applications with such low energy demands that a connection to the electricity grid would not be economical (light signals, parking meters, etc.).
These devices must be equipped with accumulators capable of accumulating excess electricity produced during the day to power the equipment at night and during cloudy periods, usually solar batteries.
They are also used in large grid-connected systems, although the power supply is variable in daily and seasonal conditions. Therefore, it is difficult to predict and not programmable.
This discontinuity makes it challenging to meet electricity demand at any time, except for production with a wide margin of safety above annual demand peaks. However, being the peak of production of solar power plants in the summer, it manages to offset the greater internal demand due to air conditioners.
What are the pros and cons of solar power?
The use of solar energy involves specific pros and cons.
The main criticisms or drawbacks are:
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High investment cost per kilowatt obtained.
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It offers very high efficiency.
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The performance obtained depends on the solar schedule, the weather, and the calendar. For this reason, it is difficult to know what electrical power we will be able to obtain at a given moment. This drawback disappears with other energy sources, such as nuclear or fossil energy.
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The amount of energy it takes to make a solar panel. Producing photovoltaic panels requires a lot of energy, often using non-renewable energy sources such as coal.
On the other hand, you have to consider the benefits of solar energy:
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Its advocates support cost reduction and efficiency gains due to economies of scale and technological improvements in future solar systems.
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Regarding the absence of this energy source at night, they also point out that the maximum peak of electrical consumption is reached during the day, that is, during the maximum production of solar energy.
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It is a renewable energy source. In other words, it is inexhaustible.
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It is non-polluting energy: it does not generate greenhouse gases and, therefore, does not contribute to aggravating the problem of climate change.