AbstractA solution for the simulation of solar-thermal installations is presented, allowing not only to Investigate the effect of construction parameters of solar-installations on the energy output (like collector area, storage volume, and so on) but also provides a means for quantifying the influence of the control parameters of the solar systems. The simulation may be controlled interactively and the progress of simulation can be visualized or can be recorded for detailed offline evaluations. Emphasis is on the special problems and advantages when such a complex system is modelled within the limits of a general purpose minicomputer system.