Analysis of power supply possibilities through lithium batteries connected to the AC grid

Abstract

In this paper we present a techno-economical analysis of grid-connected lithium batteries. A time-of-use (TOU) electricity tariff will be considered so that batteries can be charged during hours of low electricity price and discharged during hours of high electricity price. Four cases will be studied, depending if it is allowed or not to inject electricity to the AC grid during the discharge of the batteries and also depending if there is photovoltaic generator. Case 1: batteries discharge just to meet the load (no electricity injection to the grid); Case 2: Batteries discharge meet the load and also inject to the grid; Case 3: Photovoltaic generator + case 1; Case 4: Photovoltaic generator + case 2. In all the cases, the Net Present Cost (NPC) is calculated. All the cases are compared to the base case of supplying electricity without batteries. The Li-ion battery cost must be reduced at least 70% to be profitable in this applications. In that case, if selling electricity to the AC grid is allowed and the selling price is 70% of the price of the electricity, the battery system can be a good option, with or without PV generator.