This master thesis is about renewable sources of energy and their impact on older, more conventional systems i.e. possible savings such an implementation could achieve and increases in system efficiency, with the added benefit of reducing emissions of carbon dioxide. In this thesis, the focus is on battery energy storage systems. Analysing different battery chemistries, their characteristics and benefits as well as potential downsides in their use in such systems, it was decided that the Li-ion batteries will be used for task at hand. The task itself revolves around analyzing a water pumping station and see how adding a battery energy storage system could change its characteristics. By using the Matlab and Simulink software suites, the station and battery systems were modeled to ensure constant output flow to match the mean value of the volume of water sold in 2020. An estimate was conducted in which the prices of electrical energy in Croatia were used to calculate the expenses of both scenarios and to see if there is a possibility of savings and even room for profit. Lastly, by using the commerce platform Alibaba a search was conducted to find accessible battery systems that would accomplish the task that was set and to calculate the return on investment. The results of the analysis show that using a battery energy storage system in the water pumping station does achieve a solid amount of savings and that there is a significant volume of batteries that can accomplish this task. The results of the return of investment calculation however show that only two battery systems meet the criteria to achieve a return on investment and they have been recommended.