Solar energy
What is solar energy?
Solar energy is an inexhaustible source of renewable energy, and is a sustainable and clean alternative to polluting energy sources. Through photovoltaic and solar thermal installations, this energy is transformed into clean electricity, contributing to the fight against climate change, avoiding tons of greenhouse gas emissions each year.
Solar energy is a form of renewable energy obtained directly from the sun. Solar radiation or heat is harnessed to generate electricity, making it a clean and sustainable alternative to conventional energy sources that produce polluting emissions.
It is an inexhaustible and abundant source of energy, as the sun continuously emits enormous amounts of radiation that can be harnessed. Furthermore, its use contributes to reducing dependence on fossil fuels and mitigating climate change by not generating greenhouse gas emissions during operation.
Solar energy is obtained through technologies such as photovoltaic and solar thermal. Photovoltaics converts sunlight directly into electricity through solar panels, while solar thermal uses mirrors to concentrate the sun's heat to generate steam that drives turbines to produce electricity.
Why is solar energy key?
Solar energy has become a fundamental pillar in the transition towards a cleaner and more sustainable energy model. Its ability to generate electricity without direct CO₂ emissions places it at the heart of a decarbonised economy, enabling the gradual replacement of fossil fuel sources and helping to advance climate goals.
Furthermore, solar energy plays a key role in strengthening energy security. As a local and abundant resource, it reduces exposure to the volatility of international markets and the geopolitical tensions associated with the supply of fossil fuels, bringing greater stability to the system.
In this context, its deployment also helps to reduce energy dependence on external sources, promoting a more resilient and sustainable model. Its speed of installation and cost-competitiveness make it one of the most effective technologies for accelerating this shift in model.
Overall, solar energy acts as a driving force behind the electrification of the economy, facilitating the development of solutions such as electric mobility, efficient heating and cooling, and self-consumption. All of this drives a cleaner, more flexible energy system that is adapted to the needs of the future.
Advantages of solar energy
The advantages of solar energy are varied, obvious in some cases, but mostly indicative of how it can provide us with clean and abundant energy.
Inexhaustible source of energy
Since it comes from the sun, we are guaranteed a constant supply of solar energy for a few billion years to come, which makes it a renewable energy source that comes from an inexhaustible source.
Clean energy
The next advantage, in order of importance, is that solar power generation produces no greenhouse gas emissions, which helps to mitigate climate change and reduces the environmental impact of its use.
Low operating and maintenance costs
Another advantage of solar energy systems is that they tend to have low operating and maintenance costs, which can contribute to a more stable and predictable energy supply.
Renewable energy versus fossil fuels
The use of solar energy means reducing our reliance on non-renewable fossil fuels. This helps to make us less vulnerable to price fluctuations and contributes to maintaining a well-balanced energy mix.
Decentralised energy
Another notable advantage is that it is a naturally generated source of energy, and can also be considered decentralised: solar energy can be harnessed in a variety of settings, from large-scale solar farms to smaller commercial and residential installations. Furthermore, both private individuals and businesses can generate their own electricity, which helps to create a more efficient electricity grid and leads to savings for consumers.
How does solar energy work?
The process of capturing solar energy is divided into four distinct phases when it comes to photovoltaic solar energy: capturing light, generating electricity, transforming it into alternating current and storing or transporting it.
Firstly, light is collected by photovoltaic solar panels. These are composed of photovoltaic cells that contain, in turn, layers of semiconductor materials. These materials are capable of absorbing photons and releasing electrons.
The electrons released by these materials generate an electric current that flows through the conductors present in the installation. This direct current is sent to the inverter, where it is transformed into alternating current, suitable for storage or transport (Would you like to know more about the differences between alternating current and direct current?)
In the case of solar thermal energy, light is captured by mirrors and heat receivers. The process of harnessing solar thermal energy to produce electricity is based on principles similar to those of steam engines, which use it to drive a turbine that activates an electric generator.
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Types of solar energy
Solar energy is obtained through two main technologies: photovoltaic energy and solar thermal energy, either to generate electricity, in the first case, or heat in the second. This generation is produced in a clean and sustainable way, but how do these technologies work?
Photovoltaic solar energy
Photovoltaic solar energy is based on the photovoltaic effect, which is the ability of certain materials (usually silicon) to generate electricity when exposed to sunlight.
Solar thermal energy
Solar thermal energy harnesses the sun's heat to generate electricity through the use of mirrors and heat receivers. These mirrors, called heliostats, reflect and concentrate sunlight onto a receiver, where the concentrated sunlight heats a heat transfer fluid (e.g., oil) to high temperatures. This fluid is used to heat water, which in turn generates water vapour.
The steam is then directed to a turbine that drives an electric generator, where electricity is produced. In addition, in some installations, some of the heat received from the sun is stored in molten salts or ceramic materials so that electricity can continue to be generated even when the sun is not present, such as at night or on cloudy days.
Passive solar energy
Passive solar energy refers to the use of light and heat directly, without transforming it into other energy. A passive house , for example, can include from its initial design phase the appropriate elements to collect, store and distribute solar energy in the form of heat in the winter, as well as to repel external heat in the summer. Such constructions allow considerable energy savings of up to 70 %.
There are several ways to achieve this energy efficiency: using large windows to absorb the maximum amount of sunlight in winter; arranging the glazing to face the sun; or using thermal mass materials that absorb and store heat during the day, among other solutions.
The main advantages of passive solar energy are that there is little or no maintenance and no additional costs are required to perform its task. In addition, it is a technology that does not emit polluting gases during operation.
At Iberdrola we are committed to solar energy
In line with our Strategic Plan 2025-2028, solar photovoltaic technology forms a significant part of our investments in renewables for the period. At Iberdrola, we are committed to the fight against climate change, which we make a reality through our renewable facilities around the world.
In the case of solar energy, our technologies will be supported by 10 % of renewable energy investments in this period (€21 billion) and this will allow us to expand our installed solar capacity by some 2,100 MW.
Among the most important photovoltaic facilities managed by our Group are True North, Avangrid's largest solar PV project in Texas, or Lund Hill, the largest solar project in Washington.
In Spain, we have installations and projects in various privileged regions in terms of available solar resources, such as Extremadura, Castilla-La Mancha, Murcia and Aragon. Among them, the Núñez de Balboa solar power plant stands out as one of the largest solar power plants in Europe; Cedillo, which has presented an engineering challenge whilst ensuring minimal environmental impact; Ciudad Rodrigo and Ceclavín.