Stagnation state of a solar thermal system
The stagnation state of a solar thermal system is a standstill of the solar collector circuit .
Stagnation can have different causes. It usually occurs in summer when the heat storage tank is already full and the additional heat from the solar collector can no longer be dissipated. A power or pump failure can also be the cause. When the heat storage tank has reached the highest specified temperature, the pump switches off automatically. The liquid in the collectors then heats up to the point where the solar liquid evaporates. When the system has cooled down sufficiently, the circulation pump switches on again and the liquid is pressed back out of the expansion vessel. This state is planned and uncritical. However, the system components in the collector circuit are exposed to high temperature loads, which can be particularly problematic for the solar fluid . A system should be designed in such a way that stagnation occurs as rarely as possible. It can be more or less avoided through good system planning. It depends, among other things, on the size of the buffer storage tank, the size of the collector field and the solar coverage . With certain types of systems such as the drain-back system , stagnation is automatically prevented.
literature
- Chapter 5.1 Collector standstill. In: R. Stieglitz, V. Heinzel: Thermal solar energy: Fundamentals, technology, applications , Springer-Vieweg, Berlin / Heidelberg 2012, ISBN 978-3-642-29474-7 , pp. 274-278
- Standstill or stagnation temperature. In: Leukefeld , Baer, Hüttmann: Modern heating with solar thermal energy: Security in the changing world of energy technology , Publisher: Solare Zukunft, 2nd edition from 2015, ISBN 978-3-933634-44-3 , pp. 33–34
- Peuser, Remmers, Schnauss: Long-term experience of solar thermal energy , Solarpraxis, Berlin 2001, ISBN 3-934595-07-3 , p. 200