This paper presents an optimal scheduling for the utilization of the battery energy in order to minimize the cost of the electricity bill in a non-residential building equipped with a photovoltaic-storage system. The battery storage device is connected at the DC-link of the photovoltaic system for enabling a more efficient grid integration through a common central inverter. For the optimal scheduling method, the day-ahead electricity pricing and the next-day forecasted building load and PV generation for each quarter hour are taken into consideration. The problem is formulated as a mixed-integer linear programming model and is solved using commercial solvers. Furthermore, the efficiency curve of the inverter is approximated by a discretized step function and along with the battery efficiency are included in the formulation. Two case studies are carried out using real data and useful results according to the energy flow in the system and the profit are obtained.