Solar thermal energy or how to harness the sun's heat

The operation of solar thermal energy is relatively simple but highly effective. The process begins with the capture of solar radiation by solar collectors. These devices can take various forms, such as flat-plate or cylindrical-parabolic collectors, but they all share the same objective: to capture the sun's energy and use it to heat a fluid circulating through them, such as water or thermal oil. In fact, this heat can be used directly to heat water for domestic or industrial use, or it can be used to generate electricity through a conventional thermodynamic cycle. This is where the integration of other elements, such as solar panels and the thermosyphon, comes into play.

The thermosyphon, on the other hand, plays a crucial role in the efficient distribution of the heat generated by the solar collectors. This solar thermal device uses natural convection to transfer the heat from the fluid heated by the solar collectors to a water storage tank. In this way, the thermosyphon allows this solar heat to be used to heat water without the need for pumps or other mechanical devices.

Once the thermal fluid has transferred its heat to the storage tank through thermosyphon, this solar thermal hot water can be used for diverse applications. It can power domestic heating systems, provide domestic hot water, or even drive industrial processes that require heat.

Although both harness the sun's energy, photovoltaic and solar thermal energy are different not just in their operation but also in their applications and durability:

• Principle of operation. While solar thermal energy uses the sun's heat to generate heat, photovoltaic energy directly converts solar radiation into electricity through the photoelectric effect in solar cells

• Applications. Photovoltaic energy is mainly used for electricity generation, both on a large scale in solar plants and on a low scale in domestic installations. On the other hand, solar thermal energy is used, mainly, to obtain solar thermal hot water, heating and cooling applications in diverse sectors and, more residually, electricity production.

• Durability. Although it is true that photovoltaic and solar thermal energy are renewable energies, they also show differences in terms of durability and maintenance. Solar thermal energy is usually subject to greater wear, which reduces the useful life of the installations compared to photovoltaic energy. In any case, both are complementary technologies that make the most of the sun's power to provide energy.
  

At Repsol, we promote different projects capable of redefining energy self-consumption in the home with solutions that enable progress while improving the energy efficiency of the power system and boosting sustainable energy consumption.

Our Solar360 solar panel project, for example, is designed by applying the latest technologies on the market -such as artificial intelligence in the batteries of the panels- for performance optimization. The proposal allows comprehensive photovoltaic self-consumption solutions to be offered to private customers, homeowners associations, and companies, through the installation of solar panels. And not just that. The company's lines of work go beyond seeking to promote the development of renewable energies in the agricultural and livestock sector, for example, through agrovoltaic energy projects. It's about exploring alternatives that allow the optimization of solar energy in other fields, such as what occured with the agreement reached with Powerful Tree. Among other things, this pilot project explores an active shading model in wine estates in which, through the movement of photovoltaic panels, the needs of the vines themselves are met while at the same time generating renewable energy.

The development of these and other energies of renewable origin, which complement photovoltaic and thermal energy, has a lot to do with everyone's commitment to achieve a low-emissions future. The drive for that collective responsibility is also present in Repsol's strategy with proposals such as Solmatch, the collective self-consumption energy solution as a service, based on a combination of solar and grid energy.