Solar energy is the energy that comes from the Sun and that we can capture thanks to solar radiation. This energy source represents the main energy source on Earth. Because it is an inexhaustible source, it is considered a renewable energy.
Many other energy sources are derived from this energy, such as:
- Wind energy, which uses the force of the wind. The wind is generated when the Sun heats large volumes of air.
- Fossil fuels, which come from organic decomposition. The organic decomposed were, to a large extent, plants that carried out photosynthesis.
- Hydraulic energy, which uses the potential energy of water. If solar radiation would not be possible the water cycle.
- The energy from biomass, which once again is the fruit of the photosynthesis of plants.
From the energy point of view, it is an alternative energy to classic fossil fuels, it is considered a renewable energy. Solar energy can be exploited appropriately through different technologies and for different purposes, even if in technological versions that do not include energy storage.
Examples of solar energy
Some examples of use of solar energy are the following:
- Installations with photovoltaic panels to generate electrical energy. These facilities are used in homes, mountain shelters etc.
- Photovoltaic plants. They are large extensions of photovoltaic panels whose objective is to generate electricity to supply the electrical network.
- Solar cars. It converts solar radiation into electricity to drive an electric motor.
- Solar cookers. If systems to concentrate the radiation at one point to raise the temperature and be able to cook.
- Heating systems. With solar thermal energy, a fluid can be heated that can be used in a heating circuit.
- Pool heating.
Types of solar energy
There are three types of solar energy:
- Photovoltaic Solar Energy. Thanks to a physical effect, radiation from the Sun can generate an electric current. It is therefore a way to convert this resource into electricity.
- Thermal solar energy. This system takes advantage of the heat capacity of the Sun. Solar radiation is converted into thermal energy to heat a fluid that can be used for heating, sanitary hot water. In solar thermal power plants, steam is generated and, subsequently, electricity.
- Passive solar energy. This is a resource to take advantage of solar heat without using external resources. The architects can orient the houses, decide where they put windows taking into account where the solar radiation will be received.
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 Earth, we can take advantage of it in many ways:
- Using solar panels with photovoltaic cells. Photovoltaic panels are composed of a material that when receiving light directly ionize and release an electron. With the sum of several electrons, an electric current and electricity are generated.
- Through solar collectors. Solar collectors 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 do have a fluid at a high temperature that can be used in many applications.
- Passive solar energy. Passive solar energy systems are characterized by the use of solar energy without any external energy input. For example, architectural designs that allow maximum solar radiation in winter and that avoid excess heat in summer.
When we talk about solar energy we are referring to the electrical or thermal energy that has been generated by solar radiation. However, from a physical point of view, solar energy is produced in the Sun. Millions of nuclear reactions are generated in the Sun, releasing an enormous amount of energy that reaches us in the form of electromagnetic waves.
What are solar panels and modules?
The term solar panels is used for both methods (photovoltaic and thermal). However, the design is significantly different depending on what type of solar technology is to be used:
The solar thermal panel uses solar rays to heat a liquid with special characteristics, contained inside, which transfers heat, through a heat exchanger, to the water contained in a storage tank. In these cases thermodynamics plays a fundamental role.
The photovoltaic panel exploits the properties of particular semiconductor elements to produce electrical energy when subjected to solar radiation. Thanks to the so-called photovoltaic effect, solar exposure causes the movement of electrons in a component (usually silicon), generating a continuous electric current.
There is also the concentrating solar panel that uses a series of parabolic mirrors with a linear structure. The purpose of these mirrors is to transport the sun's rays over a receiver tube that circulates a heat transfer fluid or a series of flat mirrors that concentrate the rays at the end of a tower. In both cases, the receiving apparatus is heated to very high temperatures (400 ° C ~ 600 ° C).
Uses of solar energy
Solar energy has many uses and applications that can be summarized in three points:
- Obtain electricity in a sustainable way.
- Get heat without burning fossil fuels. Generally hot water.
Domestic hot water
Currently, solar panels are used to supply domestic hot water (solar thermal energy) 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 found wide application due to the low performance of these power plants compared to the high administration costs and discontinuity of the electricity supply.
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.).
Obviously, 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 amount of power supplied is variable in both daily and seasonal conditions and is therefore difficult to predict and not programmable.
This discontinuity makes it difficult 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.
Advantages and disadvantages
The use of solar energy involves certain advantages and disadvantages.
The main criticisms or drawbacks are:
- High investment cost per kilowatt obtained.
- To offers a very high efficiency.
- The performance obtained depends on the solar schedule, the weather and the calendar. For this reason, it is difficult to know exactly what electrical power we will be able to obtain at a given moment. This drawback disappears with other energy sources such as nuclear energy or fossil energy.
- 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 advantages of solar energy:
- Its advocates support cost reduction and efficiency gains in the near future due to economies of scale and technological improvements in future solar systems.
- Regarding the absence of this energy source at night, they also point out that the maximum peak of electrical consumption is actually reached during the day, that is, during the maximum production of solar energy.
- It is a renewable energy source. In other words, it is inexhaustible.
- It is a non-polluting energy. It does not generate greenhouse gases and, therefore, does not contribute to aggravating the problem of climate change.