Building integrated renewable energies
Design and execution of outstanding projects

Thermal Solar


Thermal solar for heating and domestic hot water preparation



Thermal solar energy is the result of solar radiation transformation into heat.


It can be used either for buildings and domestic hot water heating thanks to a solar water heater which is composed of panels (or solar collectors) where a heat transfer fluid is heated. The hot fluid circulates into pipes and contributes to heat up a water tank.


The standard thermal solar installations are limited by the overheating phenomena that appears when the storage tank is at maximum temperature while the solar pannels are still collecting heat from the sun. A too high temperatures and pressures can deteriorate the overall system. Anti-freezing fluid, pumps, seals and hydraulic system will age prematurely. This will increase the cost of maintenance.


For individual solar water heater, the installation is often undersized in order to prevent this overheating issue.


For combined solar thermal systems (building and water heating), overheating is unavoidable in summer period.


The STC ® technology developed by 2ES provides an effective response to this matter. One can find a bref description of this technologie in this website / our competences.




The most common panels are glazed flat-plate collectors

 thermal solar panel
  • the front glass is a protection for the assembly and enhances efficiency


  • the absorber transforms the sun radiation into heat


  • the insulator limits thermal losses


  • the coil is the heat exchanger in which circulates the heat carrying fluid


  • the heat transfer fluid removes the heat stored by the absorber


Some other technologies are available on the market : the evacuated tube collectors or the unglazed collectors.