This thesis defines the main characteristics of Battery Energy Storage Systems (BESS) and performs a techno-economic feasibility study to evaluate their potential application in Italy. Once explicated the context of analysis, the work mainly consists in a model created on Excel, Excel VBA and MATLAB to simulate multiple case studies based on the current Italian regulation. The model is divided in parts that emulate the behaviour of a BESS + coupled plant (property of BKW Italia S.p.A.) combination from various perspectives. The chosen technology are Li-ion batteries, with particular attention paid to the lithium iron phosphate/graphite (LFP/graph) chemistry. Firstly, there is an introduction about why storage importance is globally increasing, and which is the base knowledge that is necessary to understand BESS.