Thermoelectric generators (TEGs) make use of the Seebeck effect in semiconductors for the direct conversion of heat into electrical energy, being of particular interest for high reliability systems or for waste heat recovery. Although several TEG models can be found in the literature, many of them not offer a theoretical solution because they are based on steady-state solutions or they are assuming fixed parameters as boundary conditions. Consequently, to assess and optimize thermoelectric generators in real applications a numerical transient simulation tool, which takes into account the whole energy system, is mandatory. For that purpose, a new TRNSYS type is developed. This TEG component, which can be used as a design tool, is presented in this paper and validated using experimental data. The results show that the proposed component is able to cope with both thermal and electrical dynamics. The comparison between theoretic and experimental results has approved the reasonability of the new component. The normalized root mean square errors are 3.53% and 2.33% for temperature difference between hot and cold sides and electrical output power, respectively. (C) 2014 Elsevier Ltd. All rights reserved.