Renewable Energy Sources (RES) are defined as energy sources, which are abundant in the natural environment. It is the first form of energy that man used before turning intensely on the use of fossil fuels. RES is practically unlimited, its use does not pollute the environment and its exploitation is limited only by the development of reliable and economically acceptable technologies that will have the purpose of unlocking their potential. Interest in the development of these technologies first emerged after the first oil crisis of 1974 and was consolidated after awareness of the world's major environmental problems over the last decade. For many countries, RES is a domestic source of energy with favorable prospects of contributing to their energy balance, contributing to reducing dependence on expensive, imported oil and enhancing the security of their energy supply. At the same time, they contribute to improving the quality of the environment, as it has now been established that the energy sector is the industry primarily responsible for environmental pollution.

The main advantages of Renewable Energy Sources are:
 
  • They are practically unlimited sources of energy and help reduce dependence on exhausting conventional energy resources.
  • They are environmentally friendly and their use responds to the global effort to reduce pollution.
  • Because they are scattered across different areas, they result in the decentralization of the energy system and the dismantling of infrastructures, covering local and regional ones. This dispersion has an additional effect, that of reducing energy transmission losses.
  • Because they are domestic, they contribute significantly to national energy independence and security.
  • They have low cost of use that is not affected by fluctuations in international fossil fuel prices.
  • Investing in RES generates many jobs, especially at a local level.
  • In many cases, they contribute to social and economic upgrading and development of local areas, by promoting investment and reducing unemployment.

Renewable energies, apart from their significant advantages, they also have some characteristics that make their exploitation difficult.
 
  • Because they are scattered, there is no possibility of gathering and storing in large quantities of power.
  • The density of energy and power contained is generally limited, and so large production requires large installations.
  • The rate of exploitation of their facilities is low because their availability is sometimes limited and fluctuating. This also raises the need to use other sources of energy, so that the cost of energy is rising.
  • The investment cost for RES power plants is still high compared to conventional forms.