The purpose of this paper is to propose a simulation method that can calculate the effect of solar thermal equipment, the amount of heat available from solar heat, in a simple and quick manner. In this calculation logic, solar thermal equipment is decomposed into its mathematical elements, modeled linearly, and calculated in series. This simulation includes the characteristic values of the equipment, which have been experimentally measured in accordance with JIS (Japan Industrial Standard Committee). The calculation accuracy was confirmed by comparing it with the experimental data, and its usefulness as a simulator was verified.