Solar Water Systems

Save Energy

Solar Thermal Systems can provide free hot water to the households in Bulgaria


The Sun radiates enormous amounts of energy from its 6,000°C surface. Only a small percentage of this reaches the Earth. However, in Bulgaria we still receive on average an amount of energy equivalent to over 75% of that arriving at the equator.

Solar energy technologies could be successful and viable in the Bulgarian climate. It doesn’t even need to be sunny, just as long as it is light. Solar thermal technologies are involved with harnessing the sun’s heating effect.


Most often a solar thermal system usually consists of panels mounted on the roof of a building which are designed to capture solar energy and use it to heat water. There are four main types of solar collector, which can be used in solar hot water systems:

  • evacuated tubes
  • selective surfaced flat plate
  • non-selective surfaced flat plate
  • unglazed plastic collectors

A selective surface flat plate collector is one which is good at absorbing energy but does not radiate much energy back to the atmosphere. The less expensive unglazed plastic type of collector is used exclusively for outdoor swimming pools where lower water temperatures are required and are not eligible under the REECL Programme.

Evacuated tubes and both types of flat plate collector are best used for solar water heating systems for houses and other types of buildings. A well-designed system can, for instance, provide around 50 to 70% of the annual hot water requirements for a home in Bulgaria.

A solar thermal system is not generally suited to space heating in REECL, except for very well-insulated buildings and in combination with another heating source, since the greatest demand for heating comes in the winter months when energy from the sun is at its lowest.

There are not many buildings in Bulgaria fitted with solar thermal panels, however, over the last few years the number is rapidly growing.

An approach which is growing in several European countries is installing large scale solar heating systems on groups of houses, blocks of flats or community buildings. The larger scale tends to make the systems even more economically viable.

Benefits of Using Solar Thermal Systems:

  • Can provide the majority of hot water supply
  • Very low running costs
  • Using the Sun’s energy reduces our consumption of conventional fuels and helps to reduce the emissions of harmful greenhouse gases