In the frame of EU FP7 funded project COMTES, a closed sorption storage system based on water as absorbate and sodium hydroxide as absorbent was developed and a demonstrator with 18m² of vacuum tube collectors, 3 water buffer tanks, and a sorption storage unit was built into a shipping container. The demonstrator was put into operation and the performance of the system was evaluated. Key performance indices were derived based on simulations for 4 varying building types and 4 different climates. A new TRNSYS17 Type was developed and as far as possible calibrated with measurements from the demonstrator plant. Two simulation series are presented, one with a standardized storage system, the other to reach 80% solar fraction. The sorption storage system proves to be an important additive to purely sensitive storage for buildings with higher heat demands and for locations with long periods of insufficient solar radiation.