In this paper theoretical cost analysis of a 10 MW wind turbine with lithium-ion batteries as storage for an Off-grid Island community is made. The Vestas V164-10.0 MW  wind turbine is considered for calculations. Calculations are calculated using numerical computation, and figure data is collected using MATLAB software. The paper aims to give researchers and investors a rough idea about the economic outcomes of using Li-ion batteries as a storage system for wind turbines. The surplus energy needed to be stored is calculated, and then the cost of the system is calculated numerically, targeting the return on investment. If the return on investment of a system is lower than 8%, then investors do not invest in such a system. The return on investment in these calculations is about 17%.