The Pillow Plate (PP) geometry for heat exchanger applied to latent heat thermal energy storage (LHTES) is rapidly gaining interest in the scientific community. Thanks to the swelled shape and manufacturing simplicity it can enhance the heat transfer performance, guarantee high mechanical resistance and ensure low production costs with respect to other heat exchanger geometries. Abundant and relevant studies investigated the thermo-fluid dynamic characteristics of PP heat exchangers (HEXs) but very few studies concentrated in understanding PP technical and economic potential when applied to LHTES. This thesis aims at developing an innovative procedure for the optimal design of PP-LHTES. The methodology consists in the development of two models: a 1D analytical discretized stationary model, called the design model, and a 1D analytical discretized dynamic model, called the dynamic model.