The paper presents a review of seasonal solar energy storage technologies for heating of buildings. Actual national and international energy strategies generally encourage the use of renewable energy sources. Thermal energy storage (TES) offers various opportunities in the design of renewable energy systems especially solar energy. Thermochemical heat storage has gained popularity among researches because of higher energy density and lower heat loss compared to sensible and latent heat storage. On the other side solar energy has been recognized as one of the renewable energy sources with the most potential. The first part of this paper is a review of thermochemical heat storage technologies and systems with emphasis on systems involving solar energy utilization in buildings with examples from abroad (Denmark).The main part of the paper is a presentation of adsorption prototype system made in the Laboratory for Heating, Sanitary and Solar Technology at University of Ljubljana. The system includes the working pair silica gel and water vapour. The storage consists of two main components: adsorber and evaporator/condenser. Silica gel represents the adsorption material and is in the form of granules. The connection between the adsorber and the evaporator/condenser is valve. The last part of the paper is presentation of numerical models that are used for seasonal storage calculations. TRNSYS (TRaNsient SYStem) is one of the most popular simulation system programs. It is a complete and extensible simulation environment that deals mainly with the problems associated with systems having transient behavior such as solar energy applications, buildings thermal analysis, electrical systems, HVAC etc. We have used the program to simulate the solar energy application with seasonal thermochemical heat storage.