Photovoltaic and solar thermal are two renewable energy sources. Both systems are based on the use of solar energy. Solar thermal uses heat and photovoltaic power systems to generate electricity.
Although solar PV and solar thermal are both systems powered by solar radiation, there are several differences:
Type of energy obtained: PV generates only electricity. Thermal solar stations convert sunlight into heat. This heat can be used directly, but solar thermal power plants use it to obtain electrical energy.
Different cost of solar panels. Photovoltaic panels are more expensive than solar collectors.
Energy storage techniques. Photovoltaic can supply energy directly or store it in batteries. On the other hand, solar thermal can only be stored in solar accumulators.
Solar Thermal Energy
Solar thermal technology consists of harnessing solar radiation to obtain thermal energy (heat). They are also known as solar thermal plants.
The heat obtained is used for the production of hot water for domestic consumption. It can be used for domestic hot water (DHW) or heating. It is also called solar water.
Thermal solar energy can also generate electrical energy.
The technique of this type of thermoelectric plants is based on concentrating the solar radiation in a single point. Reflectors or parabolic troughs are used to achieve this.
In this way, the temperature of the working fluid can be raised to hundreds of degrees Kelvin. In this way, it is possible to generate steam and operate steam turbines. The turbines are connected to an electric generator.
The output electric current of these plants is in alternating current.
Photovoltaic Solar Energy
PV systems only produce electricity.
If solar thermal energy needs a thermodynamic process. PV needs a chemical process. This chemical process takes place in photoelectric cells. Solar cells are made up of semiconductor materials such as silicium.
When a photon collides with the atom of one of these materials, an electron jumps. The sum of these electrons generate a direct current.
Energy production in photovoltaics PV systems is instantaneous.
Pros and Cons of Thermal Solar Energy Compared to Photovoltaic
The advantage of solar thermal energy, compared to solar PV system, is that it allows many applications.
On the other hand, photovoltaic energy only allows the generation of electrical energy.
The drawback of solar thermal energy is that it has a lower performance than that of photovoltaic solar installations. Thermal solar energy undergoes a greater number of energy transformations.
When it comes to heating water, solar thermal energy has an advantage. In this case, the heat energy is transmitted directly to the water.
Photovoltaic energy has one main disadvantage. It is that to heat water, it must first generate electricity and then heat the water with an electric heater. This system involves certain energy losses.