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Controlled Thermal Solar – STC ®


A simple, safe, effective and energy-efficient solution by 2ES.


Standard thermal solar installations are often limited by excess heat storage. This overheat phenomenon occurs when the storage tank has reached its maximal temperature while the solar thermal collector are still heated by the sun. These high temperatures and pressures are harmful for the functioning of the system. The antifreeze liquid degrades and the exposure of the hydraulic system to such high temperature leads to an accelerate ageing.

In order to minimize this problem, the surface of collectors is undersized for individual solar water heater while the problem is unavoidable for mixed solar installation.


The STC technology developed by 2ES can fix this issue and minimize energy consumption and maintenance costs :

  • an ingenious disposal for automatic solar collector drain


  • the heat exchange fluid tank is located underneath the collectors, this minimizes the height of fluid column to be drained


  • air injection device between fluid tank and collectors allows a quick complete and automatic drain as soon as the pump is stopped


  • no air is mixed to the fluid, the restart is easier, smaller pumps can be used


  • No need of solenoid valve (included in the traditionnal installations)


  • a reduced electrical consumption of the whole system because use of pumps much more energy-efficient than the traditional ones



controlled thermal solar – STC ® by 2ES