Battery energy storage systems (BESS) beсame widely popular due to availability of many energy applications (i.e. peak shaving) that can be used by private customers and office companies. Modern trends of electrification and renewable energy usage opens the door for new energy solutions that can be resolved with BESS. In addition, BESS becomes more attractive to be operated since the production of lithium-ion battery cells is increasing and the purchase price is decreasing. The following book offers variety of technological concepts how energy model can be modified or improved with presence of BESS in bidirectional power flow systems. For organizational reasons, the book is divided into different scenarios (i.e. power, frequency, consumers, communication) to make reader understand what part of BESS is ought to be improved.