un gran conjunto de paneles de energía solar

At a time when our responsibility to our planet and the environment is a top priority, it's important to know exactly what solar energy is, how it works, and how to expand its use as a source of electricity generation.

What is solar energy?

Solar energy is harnessed from the sun in the form of electromagnetic radiation (light, heat, and ultraviolet rays). By installing solar panels or collectors, it can be used to capture thermal energy (photothermal) or to generate electricity (photovoltaic).

Solar energy is one of the main types of renewable energy, and it plays a key role in the transition. It helps promote cleaner economies that protect the environment, improve people’s well-being, and ensure the sustainability of companies.

Technological breakthroughs have transformed solar energy into one of the most efficient and affordable in the renewable sector. This unlimited energy source, in addition to contributing to the sustainability of the planet, attracts investment, creates jobs, and increases the competitiveness of companies.

At a time when our caring for our planet and the environment is a priority, we should be aware of the different types of solar energy, how they work, and how their use can be extended as a source of electricity generation.

What types of solar energy are there?

Thermal and photovoltaic solar energy are the two most commonly known types, but there are other applications that are just as interesting such as:

Solar panel farm

Photovoltaic solar energy

This type of energy is harvested using a photovoltaic system, which is an installation that produces electrical energy using photovoltaic modules, capable of transforming solar radiation directly into electrical energy. Solar panels contain photovoltaic cells that when they receive direct light, they ionize and release electrons that interact with each other and generate an electrical current.

PV solar energy has gained significant momentum in recent years with the arrival of solar communities and the energy savings brought about by the new solar self-consumption installations.


colectores de energía solar térmica

Thermal solar energy

Solar thermal equipment uses solar collectors to convert solar radiation into heat. These collectors are used to collect and store solar radiation to heat water that is later used to support heating or hot water systems for hygienic, residential, or industrial use.

There’s another option called Concentrated Solar Power (CSP). In this case, the system works with a series of lenses or mirrors that concentrate sunlight on a specific surface. The energy generated by this process is used to produce electricity by using the heat to boil water to produce steam and power, for example, the turbines of a generator.

A passive home

Passive solar energy

In the case of passive solar energy, the sun's energy is harnessed directly by means of materials and construction solutions, without the need to transform it into other types of energy, as we have seen in previous cases (which could be considered active). Passive solar technology is a fundamental part of ecodesign and bioclimatic architecture, and its main use is the heating of living spaces. Natural lighting, either direct or by means of light tubes (with mirrors inside), can also be considered an example of a passive application of solar energy.

Different types of renewable energy installations

Hybrid solar energy

In this last case, any of the aforementioned types of solar energy is combined with other energies, mainly renewable ones, in order to achieve a greater energy supply.

The most common example is the combination of solar and wind energy. Hybrid photovoltaic and wind systems combine solar panels with wind turbines, making the most of the sun and wind resources.

How do the installations work to obtain active solar energy?

Solar energy requires an energy transformation of the sun's heat or radiation into thermal or electrical energy. 

  • Photovoltaic solar energy: This occurs when photons that travel through sunlight collide with the solar panel cells and produce electrons. The electrons move by exchanging positions and creating an electricity flow between the layers of the solar panel. The more intense the light, the greater the electricity flow. Find more information in Spanish here.

  • Thermal solar energy: The workings of thermal solar energy is relatively simple, consisting of a system for collecting solar energy (solar collector), a device for storing the energy obtained (collection vessel), and lastly, a way of distributing the carrier fluid for consumption.

How can solar energy be used and applied?

Technological innovation in the field of renewable energies has made it possible for solar energy to be applied in multiple areas:

  • Electricity: installing photovoltaic panels to produce electrical energy is the most widespread use of solar energy. 
  • Heating: through the use of solar thermal panels, solar radiation can be used to heat the water that powers the radiators and underfloor heating of people’s homes. 
  • Hot water: solar thermal energy in homes is a really interesting alternative for producing hot water for sanitary use due to its efficiency and sustainability. 
  • Irrigation: generating electrical energy for agricultural irrigation is one of the many different uses of solar panels. The main advantage of this system is that the season with the highest demand for water in this area usually coincides with the season with the highest solar radiation. 
  • Lighting: photovoltaic solar energy allows for the automation of street lighting, which is an interesting energy saving and a firm commitment to renewable energy sources.

Repsol and solar energy

We want to be a sustainable and responsible company that meets society’s demands. That’s why we were the first energy company to commit to reaching net zero emissions by 2050. In line with these goals, we have developed several projects in the field of solar energy:

A man reading a newspaper on a balcony

Solar communities

Repsol Solmatch is the first big Solar Community in Spain. This commitment to distributed, or decentralized generation, is based on the activation of solar communities.

How do they work? Panels are installed on homeowners' roofs for free so that households located within 550 yards can enjoy 100% renewable energy.

Solar360 logo

Solar panels on a roof of a single-family house

Solar360 is the new comprehensive self-generation solution for photovoltaic energy aimed at individual customers and businesses that offers 100% renewable energy. This turnkey product includes everything from managing the installation licenses, assembling the solar panels, and remotely monitoring installation to ensure they are in good condition.

Repsol service station with solar panels on the roof

Self-consumption solar panels

We are committed to solar panels for the energy self-consumption of our facilities. We install them in our network of service stations. Thanks to this project, we reaffirm our commitment to sustainability by promoting the use of renewable energies and caring for the environment.

Solar panels in a field

PV solar farms: Valdesolar, Sigma, Kappa, and Jicarilla

Nationally, we have three three solar farms in Badajoz, Cádiz, and Ciudad Real, which are highly favorable areas for producing this type of energy.

We've also begun to produce electricity at our first US photovoltaic plant, Jicarilla 2, located in Rio Arriba County in New Mexico.

  • The Valdesolar project, in Bajadoz, will be the largest solar park developed by Repsol that will supply electricity to around 140,000 households.
  • Kappa, the group’s first solar park, will have an installed capacity enough to supply electricity to around 71,000 households.
  • Sigma, our project located in the province of Cádiz, has an installed capacity of 204 MW
  • In terms international projects, we acquired 40% stake of Hecate Energy, which represents our first foray into the U.S. renewables market. Thanks to this transaction, we'll have access to an extensive project portfolio totaling more than 40 GW, of which 16.8 GW are solar projects in addition to 4.3 GW of batteries for energy storage. This year, we also began producing electricity at our first US photovoltaic plant, Jicarilla 2. Its renewable electricity generation will avoid the emission of nearly 50,000 tonnes of CO2 per year into the atmosphere.