First, this article introduces a comparison between experimental results and the results issued from a numerical model of a composite Trombe solar wall incorporating a concrete storage wall with the help of the Dymola/Modelica software. The validation of the model is realized from the comparison between simulated and measured heat flux, external and internal surface temperatures and fluid temperatures in a ventilated air layer. Then, the numerical model is used to simulate a composite solar wall where the concrete storage wall is replaced by a mortar mixed with microencapsulated phase change material (PCM). This allows to study and compare the thermal behavior and the energy performances of the two composite solar walls.