Solar thermal vs photovoltaic

There are two technologies to benefit sunlight for the benefit of human beings, solar thermal energy and photovoltaic solar energy, although many people confuse these technologies but in reality they work completely different.

Solar thermal energy vs photovoltaic

Although both technologies are based on the use of solar energy on panels or solar collectors,  solar thermal and photovoltaic solar energy present numerous differences  that we will try to clarify through this comparison.

First and foremost, we can understand that  solar thermal energy  is used to absorb the energy of the sun and transform it into  heat  that can be used directly to heat water or through storage, to even generate electricity (solar thermal energy), although this use is rather industrial and in this article we will focus on the use at home.

In contrast,  photovoltaic solar energy  uses the sun’s energy to transform it into  electricity . Looking a little more in detail each one of them:

Solar thermal energy (domestically)

Its main use at the domestic level is for the  production of domestic hot water (DHW) . It is a very simple technology: broadly speaking, panels or solar collectors contain a liquid inside, which is heated by exposure to the sun. Subsequently that hot liquid transfers its heat to the hot water of your home.

Let’s take a look at the  main advantages of solar thermal energy :

  • Solar thermal energy is more efficient compared to the space used than solar photovoltaic
  • The installation can easily exceed 70% efficiency in its operation
  • It is a much less complex technology than photovoltaics, and if you are a little crafty, you can install it yourself quite simply.
  • It contributes sensibly to the saving of your domestic expenses for the obtaining of sanitary hot water.

But it also has some  negative points  to consider:

  • The performance of the installation is much lower in the winter months, when the hot water needs are higher
  • Photovoltaic solar installations are more versatile than thermal installations
  • Solar collectors have shorter life
  • Frosts can affect them, the use of antifreeze in the heat transfer fluid is absolutely essential.


Photovoltaic Solar Energy

It is a more modern technology than solar thermal energy, and it still needs technical advances that improve its performance and efficiency. There are different types of photovoltaic solar panels, each with different characteristics, prices and features that are summarized in monocrystalline, polycrystalline and thin-film.

They all rely on silicon to absorb the sun’s energy and transform it into electricity.

Some of the  points in favor of photovoltaic solar energy  include:

  • They can provide clean energy for more than 30 years, with solar panels guaranteed for 20 years or more in almost all manufacturers.
  • They can cover a good part of your electricity consumption and, therefore, can contribute to a big saving to your electricity bill.
  • They are very efficient in summer
  • They are not affected by frost

But we must also take into account certain  disadvantages :

  • Higher investment for an installation of equal power to a thermal installation
  • They need more surface in roofs, roofs or gardens
  • The installation is more complex, so it is normal to use an installer to make the connections correctly and safely.
  • In Spain, except for isolated installations, photovoltaic solar installations are subject to numerous bureaucratic procedures and taxes that lengthen the time of the installation’s amortization.

In summary, seeing in a schematic way a comparison between solar thermal energy and photovoltaic solar energy, we can say that:

ApplicationsProduction of sanitary hot water, heating, pool heatingGeneration of electricity
Basic operationSimilar to creating a greenhouse effectPhotoelectric effect
Main types of panels or collectorsPlanes and vacuum tubesMonocrystalline, polycrystalline and thin-film
Average efficiency of the panels90%fifteen%
Efficiency of the system65%10%
Guaranteed lifespan10 years20 years
Average amortization time8-10 years14-16 years
Subject to a special tax / toll?Do notYes, except isolated facilities
Does the installation have to be legalized?No, if the rated power is less than 5 kWYes, except isolated facilities


In short, the use of  thermal and photovoltaic solar panels  are technologies that provide your home with clean renewable energy and contribute to a more sustainable planet. Solar thermal energy seems to be more accessible and accessible to many more people, while photovoltaic solar offers more independence from electricity companies.

The ideal would be to install both systems in your home, but everything depends on your needs, your willingness to support more or less long bureaucratic procedures and your investment capacity, taking into account that in both cases the installation will be amortized and will end up saving you a significant pinch in your household expenses.


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