Like every closed system in which a liquid's temperature changes, a solar installation also needs an expansion vessel. The Solar-plus expansion vessel plays an important role in this regard when it comes to maintaining pressure. The pressure must not rise too high when the circulation in the collector stops, but also not too low when the outside temperature is below the freezing point. The medium in a solar installation is mostly a mixture of water and glycol, having a high coefficient of expansion. Solar-Plus Expansion Tank can anticipate such temperature fluctuations and maintains the system pressure in a sitting range.