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Difference: Solar Thermal Panels Vs. Photovoltaic

In this article we will talk about the notorious differences that exist between thermal and photovoltaic solar panels.

Difference: Solar Thermal Panels Vs. Photovoltaic

Today there are many  solar panels on the market ,  however there are two main types of  solar panels,  commonly called  thermal solar panels  , which are used to heat domestic hot water, and photovoltaic panels, which are used to produce electricity.

Thermal Solar Panels for DHW 

Thermal  panels  produce domestic hot water through thermal energy, as its name suggests. There are two types:

  • Flat collector: it has a series of tubes under glass inside the panel and they are the most common
  • Evacuated tube collector: they are a superior technology to the flat collector, they are made to minimize heat losses to the outside, so they have better performance and are more expensive.

The operation of this technology is simple, the  thermal panels  contain a liquid that when exposed to the sun heats up, then that liquid transfers its heat to the water in the house.

The temperatures reached by the liquid inside this panel are higher than the ambient temperature where they are located, therefore, we can get hot water even on the coldest days as long as there is a minimum of solar radiation.

Photovoltaic panels

Photovoltaic  panels  absorb solar energy and transform it into electricity. It is a technological advance superior to that of  thermal panels  and is still in the process of improvement in both efficiency and performance.

All  photovoltaic panels  are built mainly with silicon crystals, a material that is responsible for absorbing photons of light, and then emitting electrons that help us to obtain electricity.

There are different types of  photovoltaic solar panels  that we can basically summarize in 3. We present them to you in order of efficiency and cost, with monocrystalline being the most efficient and expensive:

  • Monocrystalline, they have a single crystal that has had a controlled growth. This causes the entire surface of the panel to go in the same direction, making it the most efficient photovoltaic system.  
  • Polycrystalline, crystal growth is not controlled and therefore its surface has all directions making them less efficient than monocrystalline.
  • Thin layer, they are the most traditional panels and represent an efficiency between 7-13%, reaching 4 times lower than monocrystalline. They can be made of different materials: amorphous silicon, cadmium telluride, copper and photovoltaic cells.

What are the differences between photovoltaic and thermal panels?

If it is still not clear with the definition of each one, we leave a table with their differences:

thermal panels Photovoltaic panels
They are a simpler technology They are more advanced technology
Capture thermal energy Capture solar energy
Produces domestic hot water produces electricity
Useful life 10 years approx. Useful life 20 years approx.
Average efficiency 90% (very varied depending on time and type) Efficiency between 10 – 15% (very varied depending on the time and type)

Is there a Combination between Photovoltaic Panels and Thermal Solar Panels?

Yes, they are called hybrid panels. They produce electricity and heating both in a home and in a business.

Although there are still few companies that are researching this technology, we can highlight the company EndeF Engineering in Zaragoza (Spain). This kind of panels have the benefits of producing electricity and heat in a single panel (tripling the thermal and 15% more than the electric).

At the end of everything, we are going to opt for a photovoltaic panel or solar thermal panel depending on what our greatest need is: heating or electricity. However, there are  hybrid panels  that do both .